AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 322 PM MST SAT DEC 20 2008 .SHORT TERM... (TONIGHT AND TOMORROW) ...MAIN CONCERN IS COLD TEMPERATURES... RELATIVELY SHALLOW ARCTIC AIRMASS IS OVER THE REGION. BOUNDARY MADE IT WELL INTO NM AND TX...BUT RATON NM HAD STRONG W WINDS AND WARM TEMPS ALL DAY INDICATING BOUNDARY WAS NOT ALL THAT DEEP. ADDITIONALLY...ALTHOUGH KTAD HAD E WINDS ALL DAY...TEMPS STILL MANAGED TO GET INTO THE UPPER 30S. ELSEWHERE...I WAS EXPECTING A WEAK WARM FRONT TO DEVELOP ABOVE THE SFC OVER THE PALMER DVD TODAY...AND LOOKING AT SAT PIX IT LOOKS LIKE IT IS DEVELOPING JUST N OF THE CWA AS CLOUDS AND SOME LIGHT SNOW ARE NOTED OVER EC CO. ALSO OF NOTE...WE HAVE REASON TO BELIEVE THAT THE MONARCH AWOS WINDS ARE READING TOO HIGH. IT IS INDEED WINDY ACROSS THE CONTDVD...BUT I DO NOT BELIEVE THE WINDS ARE OCCASIONALLY IN EXCESS OF 100 MPH. TONIGHT...IT IS GOING TO GET COLD TONIGHT BUT NOT AS COLD AS EARLIER EXPECTED. NEARLY ALL...IF NOT ALL...OF THE PLAINS SHOULD REMAIN ABOVE ZERO F. VALLEYS WILL GET QUITE COLD AS TEMPS SHOULD GET TO -10F TO 0F. MOST NOTABLY...WARMER (RELATIVELY SPEAKING) TEMPS AT 700 MB WILL MOVE ACROSS THE REGION TONIGHT...AND TEMPS AT HIGHER MTN TOP LOCATIONS ARE EXPECTED TO ACTUALLY RISE AS THE NIGHT GOES ON. ANOTHER CONCERN I HAVE IS WHAT IS GOING TO HAPPEN UP ACROSS THE S FACING SLOPES OF THE PALMER DVD TONIGHT. FLOW WILL LIKELY REMAIN S IN THE LLVS BUT IT IS EXPECTED TO REMAIN QUITE SHALLOW. RUC (THROUGH AT LEAST 12H) KEEPS IT QUITE DRY. ON THE OTHER HAND THE 12Z NAM SATURATES THE LLVLS AND BRINGS CLOUDS INTO THE REGION. LATEST 18Z ALSO HAS SOME LOW CLOUDS DEVELOPING. FOR THIS REASON...WILL KEEP MOSTLY CLOUDY SKIES FOR THE GREATER KCOS REGION LATER TONIGHT INTO TOMORROW MORNING. THIS WILL HAVE MORE OF AN IMPACT TO AVIATION (BELOW). AS FOR THE MTNS...SNOW SHOWERS WILL GRADUALLY DECREASE...AND WINDS WILL BEGIN TO DECREASE AFTER SUNSET. FOR THIS REASON...I HAVE CANCELED THE WSW FOR THE C MTNS (NOTE THAT A NEW WSW HAS GONE INTO AFFECT WHICH IS IN EFFECT FROM MONDAY DAY INTO TUESDAY...SEE EXTENDED FARTHER BELOW). TOMORROW...A 2NDRY WEAK SURGE WILL MOVE IN EARLY TOMORROW...BUT THIS SURGE WILL LIKELY ONLY HAVE A MARGINAL IMPACT ON OUR WX. IT IS STILL GOING TO BE COLD TOMORROW...BUT I HAVE BUMPED UP TEMPS QUITE A FEW DEGREES FROM THE GRIDS THAT I INHERITED. TEMPS TOMORROW ON THE PLAINS SHOULD BE QUITE SIMILAR TO TODAY. TEMPS IN THE MTNS SHOULD BE NOTICEABLY WARMER AND THERE WILL BE MUCH LESS WIND. HODANISH .LONG TERM... (SUNDAY NIGHT THROUGH SATURDAY) A BRIEF REPRIEVE EXPECTED SUNDAY NIGHT WITH SHORTWAVE RIDGE TRANSLATING ACROSS THE AREA AS THE NEXT UPPER LOW DROPS INTO THE NORTHWEST US. BOTH NAM/GFS RAMP UP SNOW ALONG/WEST OF THE CONTDVD SUNDAY NIGHT AS SOUTHWESTERLY FLOW ALOFT INCREASES. LAPSE RATES NOT TERRIBLY IMPRESSIVE SUN NIGHT DUE TO WAA ALOFT. HOWEVER...OROGRAPHIC FLOW AND SOME WEAK JET DYNAMICS WILL RESULT IN SOME WIDESPREAD LIGHT SNOW FOR THESE AREAS. HAVE INCREASED POPS AFTER MIDNIGHT. BETTER DYNAMICS AND STEEPER LAPSE RATES MOVE IN ON MONDAY AS 120+KT UPPER JET AXIS MOVES ACROSS SRN CO. BOTH NAM/GFS PRINT OUT UP TO 1 TO 2 FEET OF SNOW FOR HIGHER ELEVATIONS OF THE EASTERN SAN JUANS AND SAWATCH RANGE THROUGH TUESDAY. THE HEAVIEST ACCUMULATIONS WILL FALL ACROSS THE EASTERN SAN JUAN MTS WHERE SWRLY FLOW WILL PROVIDE THE BEST OROGRAPHIC COMPONENT. LAPSE RATES REMAIN FAIRLY STEEP ON TUES AS NEXT SHORTWAVE TROF APPROACHES FROM THE WEST. GFS INDICATES A BIT OF A BREAK IN THE SNOW ON TUES WHILE NAM CONTINUES TO HAMMER THE WRN MTS WITH SNOW AT LEAST THROUGH THE MID PART OF THE DAY. GIVEN THE POTENTIAL FOR HEAVY SNOWFALL ACCUMULATIONS...HAVE OPTED TO ISSUE A WATCH FOR THE MONDAY THROUGH TUESDAY TIME PERIOD FOR THE HIGHER ELEVATIONS OF THE SAWATCH AND EASTERN SAN JUAN MTS. LA GARITAS AND THE MOSQUITO RANGES DO NOT DO AS WELL WITH SOUTHWEST TO WESTERLY FLOW...AND EXPECT AMOUNTS TO REMAIN AROUND 5-10 INCHES OVER THE 36 HR PERIOD. IF LATER RUNS CONTINUE TO INDICATE THIS POTENTIAL...EXPECT THAT THESE AREAS MAY EVENTUALLY NEED A WINTER WEATHER ADVISORY AT SOME POINT BUT GIVEN THESE AMOUNTS ARE BELOW THE 24+ HR WARNING CRITERIA WILL NOT INCLUDE THEM IN THE WATCH AT THIS POINT. MEANWHILE...GUSTY WEST TO SOUTHWEST WINDS WILL CAUSE AREAS OF BLOWING AND DRIFTING SNOW OVER THE MOUNTAIN PASSES WITH TRAVEL CONDITIONS DETERIORATING ONCE AGAIN. TEMPS WILL BE A CHALLENGE AS WELL. BOTH NAM AND GFS SHOW INCREASING SOUTHERLY FLOW SUN NIGHT ACROSS THE PLAINS WITH THE APPROACH OF THE NEXT TROF. THUS EXPECT THE SHALLOW ARCTIC AIRMASS TO ERODE SUN NIGHT ALONG THE SRN AREAS WITH WARMER TEMPERATURES DUE TO DEEP MIXING IN SOUTHERLY FLOW FOR MONDAY. HAVE WARMED UP MAXT GRID ACROSS THE PLAINS. FRONT SURGES BACK IN ON TUES. NAM CONTINUES TO PLACE FRONT JUST SOUTH OF THE ARKANSAS RIVER BY 21Z TUES. HAVE KEPT TEMPS WELL BELOW GUIDANCE ACROSS THE PLAINS...THOUGH LOCATION OF FRONT AND TIMING WILL MAKE ALL THE DIFFERENCE. BOTH NAM/GFS BREAK OUT SOME LIGHT SNOW ALONG THE PALMER DIVIDE BEHIND THE FRONT ON TUES AIDED BY SOME DYNAMICS AS NEXT TROF SWINGS THROUGH IN THE AFTN/EVENING ALONG WITH SHALLOW UPSLOPE FLOW. HAVE INCREASED POPS TO HIGH SCT FOR THIS AREA WITH 1-2 INCHES OF ACCUM. ITS CONCEIVABLE THAT THE PALMER DVD MAY NEED HIGHER POPS IF THE TIMING OF THE TROF STAYS CONSISTENT. UNSETTLED PATTERN CONTINUES THROUGH THE REST OF THE WEEK AS ANOTHER TROF MOVES THROUGH ON WEDNESDAY/WED NIGHT BRINGING ANOTHER ROUND OF SNOW TO THE CENTRAL AND SOUTHWEST MTS. WESTERLY FLOW ALOFT ON THURS WILL PRODUCE LEE TROFING AND ANOTHER WARM UP FOR THE PLAIN CHRISTMAS DAY. GFS IS NOW MORE AMPLIFIED WITH NEXT DIGGING TROF WHICH DROPS INTO THE GREAT BASIN ON FRIDAY THEN MOVES ACROSS CO FRI NIGHT/SAT. COULD SEE A GOOD CHANCE OF SNOW ACROSS THE PLAINS FRI NIGHT/EARLY SAT AS FRONT DROPS SOUTHWARD. UPPER LOW NEARLY CLOSES OFF AND H7 WINDS GO AROUND FROM THE NE SUGGESTING A TROWAL ACROSS NE CO. ECMWF IS FASTER AND LESS AMPLIFIED SUGGESTING A DRIER SOLN FOR THE PLAINS. THIS FAR OUT WILL NOT INTRODUCE ANY POPS ACROSS THE PLAINS. BUT IF THIS TREND CONTINUES WILL NEED TO INCREASE POPS AND DROP TEMPS FOR THE FRI NIGHT/SAT TIME PERIOD. -KT && .AVIATION... ONLY CONCERN IS WHAT IS GOING TO HAPPEN UP AT KCOS TONIGHT. I BELIEVE KALS AND KPUB SHOULD CONTINUE WITH VFR CONDITIONS NEXT 24H. ON THE OTHER HAND...KCOS WILL CONTINUE WITH S LLVL FLOW THROUGH THE NIGHT AND IT WILL REMAIN QUITE COLD. THIS SHOULD ALLOW A LOW STRATUS DECK TO DEVELOP WITH SOME FOG POSSIBLE. ON THE OTHER HAND...THE COLD AIR IS RATHER SHALLOW AND THERE IS A CHANCE IT WILL REMAIN CLEAR TONIGHT. FOR NOW...GIVE THE WIND DIRECTION AND THE MODIFIED ARCTIC AIR MASS...WILL LEAN MORE TOWARDS A LOW CIG IN THE TAF FOR KCOS. CLOUDS SHOULD BREAK BY MID DAY TOMORROW. && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON FOR COZ060-068. && $$ 34/31 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 1025 AM MST SAT DEC 20 2008 .UPDATE... LOTS OF CONFLICTING INFO WITH GUIDANCE LATE THIS MORNING. RUC WANTS TO SHALLOW OUT THIS AIRMASS WHILE NAM BREAKS OUT SNOW ACROSS GREATER COS AREA BY EARLY THIS AFTERNOON. BOTH MODELS MAY BE CORRECT...BUT IN CERTAIN AREAS. RUC MAY BE CORRECT IN THE SHALLOWNESS OF THE AIRMASS DOWN SOUTH AS RATON HAS BROKEN OUT WITH GUST FROM THE W AT 45 KT...WHILE LIGHT SNOW WAS REPORTED AT THE USAFA N OF KCOS. ALSO...KPUB IS GUSTING FROM THE EAST WHICH TELLS ME IT IS NOT TOO SHALLOW. I SHOULD ALSO ADD THAT THE NAM BRINGS IN A 2NDRY SHOT OF COLD AIR AROUND 12Z TOMORROW. && .AVIATION... THIS IS MAINLY FOR KCOS...AS MENTIONED ABOVE...LOTS OF CONFLICTING DATA IN THIS MORNINGS SIMULATIONS. RUC HAS W WINDS AT KCOS LATER THIS AFTERNOON WHILE NAM BREAKS OUT UPSLOPE SNOW. FOR NOW...GIVEN WHAT IS GOING ON IN CURRENT OBS/TRENDS...WILL LEAN MORE TOWARDS NAM DATA WITH ITS CLOUDIER COLDER SOLUTION. SHALLOW ARCTIC AIRMASSES ARE SUCH A JOY TO WORK...AUGGG! && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR COZ058- 060. && $$ 34 HODANISH co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 436 AM MST SAT DEC 20 2008 .SHORT TERM... (TODAY AND TONIGHT) WINDS AND TEMPS ARE THE MAIN CHALLENGES FOR TODAY. AN UPR LOW WL MOVE FROM SASKATCHEWAN INTO NORTH CENTRAL ND TODAY AND THEN INTO CENTRAL MN TONIGHT. THIS SYSTEM WL KEEP A STRONG GRADIENT OVR THE AREA AND UPR LIFT OVR THE AREA TODAY...WHICH MOVES OFF TO THE EAST TONIGHT. A FRONT HAS BEEN MAKING ITS WAY SOUTH THRU THE SERN PLAINS THIS MORNING...AT THIS TIME IT HAS MADE IT THRU KSPD...AND IS BACKING INTO LAS ANIMAS COUNTY TOWARD TRINIDAD. THE COLD AIR BEHIND THIS FRONT SHOULD RESULT IN AFTERNOON TEMPS IN THE UPR TEENS TO AROUND 20 OVR THE FAR SERN PLAINS. STRONG UPR JET (120-160KT) HAS BEEN SITTING OVR THE FORECAST AREA TONIGHT. THIS WL SHIFT EWRD THIS MORNING...BUT A NWRLY JET (120KT) WL MOVE OVR THE AREA THIS AFTERNOON. THE NAM AND GFS WINDS OVR THE HYR TRRN ARE NOT STRONG ENOUGH FOR TODAY...THE RUC WINDS LOOKED BEST OVR THE HYR TRRN SO WL USE THAT IN THE GRIDS. THE KMYP SENSOR HAS BEEN THIS MORNING HAS BEEN INDICATING SUSTAINED WINDS IN THE 50-65 KT RANGE WHICH HAD ME WORRIED ABOUT CONDITIONS ON MONARCH PASS. AFTER TALKING WITH STATE PATROL...THEY HAD INFO INDICATING THAT THERE IS A LOT OF BLOWING SNOW OVR THE PASS BUT THAT THE VSBY IS NOT THAT BAD. HAVE DECIDED TO JUST STICK WITH THE ADVISORY WE CURRENTLY HAVE IN PLACE AND PLAY UP THE STRONG WINDS AND BLOWING SNOW A LITTLE MORE. MODELS STILL DO NOT SHOW ALL THAT MUCH FOR SNOW ACCUMULATION OVR THE CENTRAL MTS. WINDY CONDITIONS ALONG AND NR THE SERN MTS WL ALSO AFFECT TEMPS FOR TODAY...MAKING THE FORECAST QUITE CHALLENGING IN THESE AREAS. HAVE KEPT THESE AREAS WARMER THAN THE REST OF THE SERN PLAINS. IN ADDITION TO THE SNOW OVR THE SW AND CENTRAL MTS...THE GFS SHOWS SOME PCPN OVR TELLER AND NRN EL PASO COUNTY THIS MORNING AND HAVE BEEN SEEING SOME ECHOES ON RADAR OVR THESE AREAS AS WELL. THE MODELS REALLY DO NOT HAVE MUCH MSTR OVR THE SERN PLAINS TODAY OR THIS EVENING...BUT WL STICK WITH THE ISOLD POPS. TONIGHT THE UPR DYNAMICS MOVE OFF TO THE EAST OF THE AREA. THERE WL STILL BE SOME ISOLD CHANCES FOR SNOW ALONG THE CONTINENTAL DVD...BUT THE REST OF THE AREA SHOULD BE DRY AND COLD. .LONG TERM... (SUNDAY-FRIDAY) LONG TERM CONCERNS CONTINUE TO BE POTENTIAL FOR HEAVY SNOWFALL ALONG AND WEST OF CONTINENTAL DVD ALONG WITH WINDS AND ROLLER COASTER TEMPERATURES AS FAST MOVING WEATHER SYSTEMS ROLL ACROSS THE REGION THROUGH THE WEEK. SUNDAY-TUESDAY...MODERATE NORTHWEST FLOW ACROSS THE REGION SUNDAY BECOMES MORE WEST TO SOUTHWEST THROUGH MONDAY AS THE NEXT SYSTEM MOVING ONSHORE ACROSS THE PAC NW COAST MOVES INTO THE GREAT BASIN REGION. WITH A COLD AIRMASS AND STRONG INVERSIONS IN PLACE ALONG WITH CONTINUED UPSLOPE ACROSS THE PLAINS...HIGHS WILL CONTINUE TO BE WELL BELOW SEASONAL AVERAGES WITH TEMPERATURES MAINLY IN THE TEENS AND 20S ON SUNDAY. WARMING WESTERLY FLOW ALOFT AHEAD OF NEXT SYSTEM TO MAKE FOR TRICKY SUNDAY NIGHT LOWS...THOUGH HAVE KEPT COOLEST TEMPS IN NORMAL COLD POCKETS ACROSS THE LOWER ARKANSAS RIVER VALLEY AND HIGH VALLEYS. POPS ACROSS THE AREA CONTINUE TO TAPER OFF WITH SLIGHT POPS REMAINING ACROSS MAINLY THE CENTRAL MTS THROUGH SUNDAY NIGHT WITH ANY LEFT OVER MOISTURE BEING RUNG OUT. TEMPS ON MONDAY REMAIN TRICKY WITH THE COLD AIR SLOWLY RETREATING EASTWARD...AND HAVE HAVE KEPT THE WARMEST TEMPS ALONG THE LOWER EASTERN SLOPES WITH INCREASING DOWNSLOPE FLOW. POPS BEGIN TO RAMP UP AGAIN ACROSS THE CONTINENTAL DVD THROUGH THE DAY MONDAY WITH MOISTURE INCREASING IN SOUTHWEST FLOW ALOFT...THOUGH SNOWFALL SHOULD BE MAINLY LIGHT THROUGH THE MORNING WITH UPPER SUPPORT BACK ACROSS THE GREAT BASIN. THE LATEST MODELS INDICATE A 120+ KT JET CORE ROUNDING THE BASE OF TROUGH ACROSS THE FOUR CORNERS REGION MONDAY AFTERNOON WHICH CONTINUES TO TRANSLATE ACROSS SOUTHERN COLORADO AS THE SYSTEM MOVES ACROSS THE ROCKIES THROUGH TUESDAY NIGHT. WITH GOOD OROGRAPHICS AND UVV AHEAD OF SYSTEM...SHOULD SEE MODERATE TO HEAVY SNOW DEVELOPING ACROSS THE SW AND CENTRAL MTS LATE MONDAY AFTERNOON THROUGH TUESDAY AFTERNOON WITH ANOTHER ONE TO TWO FEET OF SNOW POSSIBLE IN FAVORED LOCALES. AS THE JET CORE CONTINUES ACROSS THE AREA SHOULD SEE WINDY TO VERY WINDY CONDITIONS DEVELOPING ACROSS THE HIGHER TERRAIN AND LOWER EASTERN SLOPES OF SOUTHEAST MTS KEEPING OVERNIGHT LOWS MILD MONDAY NIGHT WITH ASSOCIATED COLD FRONT MOVING ACROSS THE EASTERN PLAINS TUESDAY MORNING OWNING TO KEEPING CURRENT SLIGHT POPS IN TACT ACROSS THE PLAINS FOR TUESDAY WITH HIGHS MAINLY BELOW CURRENT GUIDANCE. TUESDAY NIGHT-FRIDAY...LATEST MODELS KEEP MODERATE WEST TO SOUTHWEST FLOW ALOFT ACROSS THE AREA AS A SERIES OF SHORT WAVE SYSTEMS DIG ACROSS THE GREAT BASIN AND LIFT OUT ACROSS THE ROCKIES THROUGH THURSDAY WITH A STRONGER SYSTEM DIGGING ACROSS THE ROCKIES FRIDAY AND SATURDAY. THIS PATTERN SUGGESTS CONTINUED GOOD CHANCES OF SNOWFALL ALONG AND WEST OF THE CONTINENTAL DVD WITH MAINLY DRY AND WINDY CONDITIONS ACROSS THE EASTERN MTS AND PLAINS THROUGH CHRISTMAS DAY WITH ANOTHER MODIFIED ARCTIC FRONT POSSIBLY MOVING ACROSS THE PLAINS FRIDAY. -MW && .AVIATION...STRONG WINDS SHOULD BE EXPECTED OVR AND NR THE MTS TODAY. VFR CONDITIONS ARE EXPECTED AT THE TAF SITES...BUT THERE COULD BE SOME ISOLD SNOW SHOWERS WITH MVFR CEILINGS OCCASIONALLY THRU EARLY EVENING. && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR COZ058- 060. && $$ 28/23 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 1225 PM EST SAT DEC 20 2008 .SYNOPSIS... THE FIRST SNOWSTORM IS WELL OFFSHORE...THE SECOND ONE WILL BE DEVELOPING OVER THE SOUTHEAST UNITED STATES AND QUICKLY TRACK NORTHEAST SUNDAY AND MONDAY. ANOTHER SIGNIFICANT SNOW EVENT IS EXPECTED WITH THIS SYSTEM SUNDAY INTO SUNDAY NIGHT. THIS STORM WILL QUICKLY INTENSIFY SUNDAY NIGHT INTO MONDAY AND BRING WINDY AND MUCH COLDER TEMPERATURES TO THE REGION WITH THE START OF THE HOLIDAY WEEK. && .NEAR TERM /THROUGH TONIGHT/... MESOSCALE UPDATE... IT SEEMS WE ARE SEEING A COMBINATION OF A MOHAWK VALLEY CONVERGENCE AND RESIDUAL SURFACE TROUGHING. RUC13 IS DOING AN EXCELLENT JOB WITH SHOWING THIS CONVERENT FIELD AND SURFACE TROUGH IN THE VALLEY. GIVEN RADAR TRENDS THIS MORNING...WILL INCREASE POPS AND SNOWFALL AMOUNTS UP TO AN INCH AT THIS TIME... PREVIOUS DISCUSSION FOLLOWS... THE FIRST STORM WAS QUICKLY MOVING ACROSS THE NORTH ATLANTIC WITH RESIDUAL DEFORMATION AXIS ACROSS THE DACKS...LAKE GEORGE SARATOGA REGION AND SOUTHERN VT QUICKLY DIMINISHING. IN ITS WAKE...AMPLE LOW LEVEL MOISTURE REMAINS IN PLACE WHICH MAY RESULT IN A MAINLY CLOUDY DAY. SUBSIDENCE INVERSION DOES LOWER THROUGH THE DAY YET WIND FIELD REMAINS RATHER LIGHT WHICH WOULD REDUCE MECHANICAL MIXING OF THE DRIER AIR ALOFT. THEREFORE...WILL RETAIN THE SILVER SKY FORECAST. WITH LIMITED INSOLATION AND FRESH SNOWPACK...WILL HOLD TEMPS DOWN A BIT AND CLOSER TO THOSE VALUES WITHIN THE LAV GUIDANCE. SURFACE RIDGE AXIS FROM ONTARIO/QUEBEC OOZES SOUTHWARD THIS EVENING AS SHORT WAVE RIDGE AXIS SLIDES IN OVERHEAD. A TRANQUIL EVENING WITH PERHAPS BREAKS IN THE OVERCAST...BUT THIS WILL BE SHORT LIVED. HIGH AND MID LEVEL MOISTURE WILL INCREASE RATHER QUICKLY AS SOUTHEAST CONUS STORM BEGINS TO TAKE SHAPE. LATEST ECMWF/NAM/GEM SUGGEST DRIER AIR WILL HOLD OFF THE ONSET OF SNOW UNTIL AROUND SUNRISE WHICH IS IN AGREEMENT WITH HPC IDEA OF A SLOWER SYSTEM ARRIVAL AND ISENTROPIC ANALYSIS OF CPD/S /CONDENSATION PRESSURE DEFICITS/. SINCE THERE IS A WINDOW OF OPPORTUNITY FOR PARTIAL CLEARING...LOWER FORECAST HIGH TEMPS TODAY...AND THIS FRESH SNOWCOVER...WILL SHADE ON THE COLDER SIDE OF NAM-MOS GUIDANCE. && .SHORT TERM /SUNDAY THROUGH MONDAY/... ...ANOTHER SIGNIFICANT EVENT EXPECTED SUNDAY INTO MONDAY... H2O VAPOR LOOP CLEARLY SHOWS THE PLAYERS THIS MORNING. STILL EVIDENT THIS MORNING IS A LONG TRAIL OF TROPICAL MOISTURE WITH ORIGINS FROM THE ITCZ IN THE EASTERN PACIFIC COINCIDING WITH >150KT 300MB JET. UPPER LOW CONTINUES TO SLOWLY DIVE SOUTHWARD ACROSS THE BIG SKY COUNTRY OF MONTANA WITH IMPRESSIVE DIVERGENT FIELD ACROSS THE NORTHERN PLAINS. LEE OF THE ROCKIES...SURFACE PRESSURES CONTINUE TO FALL THIS MORNING ACROSS EASTERN KS/OK WHICH WILL LEAD TO OUR STORM EVENT ON SUNDAY. NCEP MODEL SUITE AND GLOBAL MODELS ARE IN QUITE REMARKABLE AGREEMENT WITH THIS EVENT BUT THEY DO DIFFER ON INTENSITY AND THERMAL PROFILES. THE UPPER LOW IS EXPECTED TO TRANSVERSE THE NORTHERN MISSISSIPPI RIVER VALLEY AND CENTRAL GREAT LAKES ON SUNDAY WITH AFOREMENTIONED SURFACE LOW TRACKING INTO THE TENNESSEE RIVER VALLEY. DUE TO THE APPALACHIANS...THIS SURFACE LOW WILL QUICKLY REDEVELOP OFF THE MIDDLE ATLANTIC COAST AND OUR NOREASTER WILL TAKE SHAPE QUICKLY THROUGH THE MORNING HOURS. RATHER IMPRESSIVE WARM ADVECTION PATTERN UNFOLDS AS 850MB SOUTHEAST WINDS INCREASE TOWARD 50KTS /OR GREATER/ WITH INITIAL MOISTURE FROM THE PACIFIC AND NOW THE ATLANTIC MOVING ACROSS THE REGION. ISENTROPIC ANALYSIS ON THE 290K SURFACE REVEALS A VERY IMPRESSIVE UPGLIDE/LIFT WITH 3-4 G/KG SPECIFIC HUMIDITIES. GARCIA METHOD WOULD SPELL AT LEAST 6-8 INCHES OF SNOW BUT WHEN COINCIDING WITH HIGH OMEGA VALUES INTERSECTING THE DENDRITIC ICE GROWTH...COULD SEE ANOTHER ROUND OF 1-3 INCHES OF SNOW PER HOUR SUNDAY MORNING! JUST LIKE ITS STORM PREDECESSOR...THIS STORM APPEARS TO BE A FAST MOVER WITH THE BULK OF PRECIP EXPECTED FOR 6-9 HOURS. THICKNESS SCHEMES CONTINUE TO SUPPORT THE WARMER IDEA OF SLEET/FZRA FOR PORTIONS OF ULSTER...DUTCHESS...LITCHFIELD COUNTIES WHICH WOULD LIMIT SNOWFALL ACCUMULATIONS SOMEWHAT. THE SURFACE LOW IS EXPECTED TO QUICKLY TRACK ALONG THE NEW ENGLAND COAST SUNDAY AFTERNOON AND NIGHT AND NEARLY BOMB OUT OVER THE STATE OF MAINE. THIS WILL PROVIDE A DRY SLOT TO MOVE NORTHWARD ACROSS THE CATSKILLS...MID HUDSON VALLEY...NW CT AND PORTIONS OF THE BERKS WITH A PERIOD OF LITTLE PRECIP SUNDAY NIGHT. THE EXCEPTION TO THIS WILL BE FROM THE CAPITAL REGION AND POINTS NORTHWARD. OCCLUDED FRONT BECOMES NEARLY QUASI-STATIONARY WHICH COULD PROLONG THE SNOWFALL SUNDAY NIGHT. FURTHERMORE...LAKE EFFECT SNOW/ENHANCEMENT IS EXPECTED TO INCREASE AS SUB-TEEN 850MB TEMPS MOVE ACROSS LAKE ONTARIO AND FLOW IS NEARLY WESTERLY. LASTLY..UPSLOPE CONDITIONS FOR THE DACKS AND SOUTHERN VT COULD PROLONG THE EVENT LONGER AS WELL. WE WILL EXTEND THE WATCH THROUGH THE OVERNIGHT PERIOD ON SUNDAY TO ACCOUNT FOR THESE SCENARIOS. ADDITIONAL CONCERNS WILL BE THE POTENTIAL OF CONSIDERABLE BLOWING AND DRIFTING OF THE SNOW GIVEN THE IMPRESSIVE WIND FIELD AROUND THIS NOREASTER /PERHAPS NEAR BLIZZARD CONDITIONS/. FORECAST SOUNDINGS POINT TOWARD THE POTENTIAL OF MIXING DOWN MID 40 KTS WINDS WHICH WOULD SATISFY THE POTENTIAL FOR WIND HEADLINES. ALSO...NOT TO COMPLICATE MATTERS...WITH FORECAST TEMPS DOWN INTO THE SINGLE DIGITS AND TEENS SUNDAY NIGHT...WIND CHILL HEADLINES BECOME A CONCERN AS WELL. PLAN ON HIGHLIGHTING ALL OF THESE POTENTIAL HAZARDS IN THE HWO THIS MORNING. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... ON MONDAY NIGHT...SOME LAKE EFFECT WILL CONTINUE TO AFFECT WESTERN PARTS OF THE CWA. A NW FLOW /PROB ABOUT 290-300 DEGREES/ WILL ALLOW FOR MULTI-BAND TYPE OF SNOW SHOWER ACTIVITY...WHICH COULD FUNNEL DOWN THE MOHAWK VALLEY AND POSSIBLY BRING SOME LIGHT SNOW SHOWERS OR FLURRIES AS FAR EAST AS THE CAPITAL DISTRICT...BEFORE HIGH PRESSURE NOSING INTO THE REGION FROM THE SOUTH HELPS TO LOWER THE INVERSION HEIGHT AND SQUELCH THE LAKE EFFECT. THE OTHER FEATURE MONDAY NIGHT WILL BE THE COLD. WITH A FRESH SNOWPACK IN PLACE ACROSS THE CWA...CONDITIONS WILL BE FAVORABLE FOR RADIATIONAL COOLING ACROSS MUCH OF THE HUDSON...HOOSIC...AND HOUSATONIC VALLEYS ALONG WITH THE CONNECTICUT VALLEY IN SOUTHERN VERMONT. ACROSS THE ADIRONDACKS...CATSKILLS...TACONICS...GREEN MOUNTAINS...BERKSHIRES AND DOWN THE MOHAWK VALLEY TO THE CAPITAL DISTRICT...LAKE AND TERRAIN ENHANCED CLOUDINESS WILL PROBABLY INHIBIT RADIATION. 850 HPA TEMPS BOTTOM OUT AT -16 TO -20 DEGREES C AT 18Z MONDAY AND ACTUALLY CLIMB TO BETWEEN -8 TO -16 BY 12Z TUESDAY. MEANWHILE THE NEXT IN THE SERIES OF DISTURBANCES TO AFFECT THE REGION BEGINS TO MOVE FROM THE ROCKIES TO THE SOUTHERN PLAINS AS THE 500 HPA TROF ROTATES EAST. THE HIGH OVER THE EAST COAST TUESDAY MORNING MOVES EAST INTO THE ATLANTIC WEDNESDAY AS THE LOW ELONGATES INTO A SERIES OF SURFACE LOWS ALONG THE LEADING SIDE OF THE UPPER TROF EXTENDING FROM THE SOUTHERN PLAINS ACROSS THE WESTERN GREAT LAKES INTO EASTERN CANADA. THIS FEATURE SHIFTS EAST WITH A LOW LEVEL JET OF OF 50 TO 70 KTS AT 850 HPA WHICH TAPS MOISTURE OUT OF THE GULF OF MEXICO AND BRINGS SOME OF IT INTO THE REGION STARTING WEDNESDAY MORNING WITH THE FORECAST DEWPOINT IN THE LOW LEVELS AT ALBANY INCREASING FROM MINUS 20 TUESDAY EVENING TO PLUS 6 BY WEDNESDAY EVENING...WHEN THE FRONTAL PASSAGE WILL WRING OUT MUCH OF THE MOISTURE...AND IT NOW APPEARS THAT MUCH OF THE PRECIP FROM THIS EVENT WILL COME AS RAIN RATHER THAN SNOW...WITH AROUND AN INCH OF PRECIPITATION AND SIGNIFICANT SNOW LIKELY CONFINED TO THE WESTERN AND CENTRAL ADIRONDACKS. THE GFS AND ECMWF MODELS ARE IN REASONABLY GOOD AGREEMENT ALTHOUGH THERE ARE MINOR DIFFERENCES IN THE POSITIONING AND SHAPE OF THE SURFACE LOW. NORMALLY RAIN AROUND THIS TIME OF THE YEAR WOULD SPELL A FLOOD THREAT. HOWEVER THERE IS REASON TO BELIEVE THAT AT LEAST OVER MOST OF THE REGION THE SNOW PACK WILL BE DEEP AND COLD ENOUGH TO JUST SOAK UP THE RAIN... ALTHOUGH FLOODING IS LIKELY TO OCCUR ON ROADS AND PARKING AREAS WHERE SNOW HAS BEEN PLOWED OFF THE PAVEMENT AND PILES OF SNOW BLOCKING DRAINAGE FEATURES IS LIKELY TO MAKE THE FLOODING WORSE. NOW FOR EVERYBODY/S QUESTION...WHAT WILL CHRISTMAS DAY BE LIKE? IT APPEARS THAT IT WILL BE RATHER COLD AND BLUSTERY WITH THE POSSIBILITY OF SOME LAKE EFFECT SNOW SHOWERS DOWN THE MOHAWK VALLEY WHICH JUST MIGHT PUT A FRESH FROSTING ON THE GROUND. AFTER WEDNESDAY/S BALMY TEMPERATURES THE HIGHS ON CHRISTMAS DAY WILL RANGE FROM THE MID 20S TO THE UPPER 30S. THURSDAY NIGHT WILL BE QUITE NIPPY AS THE HIGH MOVES ACROSS THE REGION WITH LOWS NEAR ZERO UP NORTH TO NEAR 20 SOUTH. FOR BOXING DAY...LOOK FOR INCREASING CLOUDS AS THE NEXT SYSTEM BEGINS TO SPREAD WARM AIR UP FROM THE SOUTHWEST WITH AN INCREASING CHANCE OF PRECIPITATION...WHICH IS LIKELY TO BE SNOW TO THE NORTH AND WEST OF ALBANY...AND A MIX TO THE SOUTH AND EAST. && .AVIATION /18Z SATURDAY THROUGH WEDNESDAY/... LOW LEVEL CONVERGENCE/DEFORMATION STILL RESULTING IN LINGERING -SN ALONG THE HUDSON VALLEY FROM KGFL-KALB-KPOU EARLY THIS AFTERNOON. BASED ON RADAR/SATELLITE TRENDS...-SN WILL CONTINUE WITH ASSOC MVFR/IFR PERSISTING INTO THE MID TO LATE AFTERNOON...WITH IFR ESPECIALLY AT KALB WHERE CONVERGENCE WILL BE MOST PRONOUNCED. AFTER THE -SN TAPERS OFF THIS EVENING...WE WILL STILL BE LEFT WITH RESIDUAL LOW LEVEL MOISTURE WITH MVFR CONDITIONS PERSISTING. THEN AS THE NEXT LOW PRESSURE SYSTEM FROM THE MID-ATLANTIC REGION APPROACHES...SNOW WILL REDEVELOP FROM SOUTH TO NORTH BETWEEN 09Z-12Z SUNDAY. CONDITIONS WILL BE DETERIORATING QUICKLY TO IFR THEN LIFR. SNOW WILL MIX WITH AND POSSIBLY CHANGE TO RAIN AT KPOU FROM ABOUT 15Z-18Z...BUT REMAIN ALL SNOW AT KGFL/KALB. WINDS WILL INITIALLY BE NORTHEAST AROUND 5 KT THROUGH THIS EVENING...THEN SHIFTING TO THE EAST AROUND 5-10 KT SUNDAY MORNING. OUTLOOK... SUN PM...MVFR/IFR...SN AT KGFL/KALB...RASN AT KPOU. SUN NIGHT-MON...VFR/MVFR...ISOLD/SCT -SHSN. WINDY. TUE...VFR...NO SIG WX. WED...MVFR/IFR...CHC SN/PL/FZRA/RA. && .HYDROLOGY... NO HYDRO PROBLEMS ARE EXPECTED THROUGH TUESDAY. PRECIPITATION IS EXPECTED TO BE MOSTLY SNOW ACROSS THE AREA THROUGH TUESDAY...WITH SIGNIFICANT WIDESPREAD SNOW AGAIN AND LAKE EFFECT SNOW POSSIBLE ON MONDAY. SNOW WATER EQUIVALENTS ACROSS THE AREA WILL LIKELY EXCEED 2 INCHES BY LATE SUNDAY. MODEL GUIDANCE IS NOW SUGGESTING THERE WILL BE A SIGNIFICANT...IF TEMPORARY...WARMUP TUESDAY NIGHT AND WEDNESDAY AS A LOW LEVEL JET DEVELOPS AHEAD OF THE UPPER TROF AND BRINGS A FLOW OF MUCH WARMER AND MOISTER AIR FROM THE GULF COAST UP THE MISSISSIPPI AND OHIO VALLEYS INTO THE REGION. DEWPOINTS ARE FORECAST TO RISE FROM THE TEENS TO THE MID FORTIES IN THE ALBANY AREA...AND EVEN WARMER FARTHER SOUTH...WITH RAIN AS THE WARMER AIR OVERRUNS THE COOLER AIR OVER THE REGION...WITH MODELS SUGGESTING ABOUT AN INCH OF PRECIPITATION. THE GOOD NEWS IS THAT THE SNOW SHOULD BE DEEP AND COLD ENOUGH TO SOAK UP MOST...IF NOT ALL...OF THE RAIN...WHERE IT IS NOT PLOWED OR SHOVELED OFF. HOWEVER THERE IS DEFINITELY A POTENTIAL FOR FLOODING OF ROADS AND PARKING AREAS...WHERE PILES OF PLOWED SNOW MAY MAKE THE FLOODING WORSE BY BLOCKING DRAIN GRATES. AND IT LOOKS LIKE ANOTHER RAIN EVENT COULD OCCUR THE FOLLOWING SATURDAY. IF YOUR HOME OR BUSINESS IS IN A FLOOD AREA...OR CLOSE TO A RIVER OR STREAM...WE SUGGEST YOU CHECK UP ON THE WEATHER DURING THIS HOLIDAY WEEK. A WARM SPELL FOLLOWED BY HEAVY RAIN COULD RESULT IN FLOODING ON RIVERS AND STREAMS. NONE IS FORECAST AT THIS TIME... BUT CONDITIONS COULD CHANGE. FOR DETAILS ON THE RIVERS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY EVENING FOR CTZ001-013. NY...WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY EVENING FOR NYZ047-051>054-058>061-063>066. WINTER STORM WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR NYZ032-033-038>043-048>050-082>084. MA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY EVENING FOR MAZ001-025. VT...WINTER STORM WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR VTZ013>015. && $$ SYNOPSIS...BGM NEAR TERM...BGM SHORT TERM...BGM LONG TERM...RCK AVIATION...RCK HYDROLOGY...RCK FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT WWW.WEATHER.GOV/ALBANY ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 650 AM EST FRI DEC 19 2008 .SYNOPSIS... A QUICK MOVING STORM SYSTEM WILL PROVIDE A HEAVY SNOWFALL TO THE REGION TODAY INTO THIS EVENING. THIS STORM QUICKLY DEPARTS TO OUR EAST LEAVING BEHIND TRANQUIL YET MAINLY CLOUDY CONDITIONS FOR THE START OF THE WEEKEND. NEXT STORM IS SCHEDULED TO ARRIVE ON SUNDAY WITH ANOTHER SHOT OF SIGNIFICANT ACCUMULATIONS FOR THE REGION. && .NEAR TERM /UNTIL 10 AM THIS MORNING/... MESOSCALE UPDATE... IMPRESSIVE SATELLITE SIGNATURE UPSTREAM WITH THE DUAL JET STRUCTURE BEING OBSERVED AND RAPIDLY COOLING CLOUD TOPS DUE THIS DIVERGENCE...PEAK CLOUD TOP TEMP WAS -66C! RADAR IMAGERY ALSO SUGGESTS CONVECTIVE BAND/S/ EXTENDING ALONG THE MI/OH BORDER TOWARD THE KPIT VICINITY WHERE SLEET WAS OBSERVED JUST SOUTH OF DTW TO CLE-CAK. LINING UP 1000-500MB THICKNESSES FROM THE RUC AND 06Z RUNS OF THE GFS/NAM ALL SUGGEST THE 543DM LINE SEEMS TO BE THE THRESHOLD. FOLLOWING THIS LINE WOULD SUGGEST THE ULSTER-DUTCHESS-LITCHFIELD COUNTIES WILL MIX WITH SLEET THIS AFTERNOON. OTHERWISE...ARRIVAL TIMING SEEMS TO BE BETWEEN 10AM-NOON FOR WEST AND SOUTH OF THE CAPITAL REGION AND BETWEEN NOON-2PM FOR THE REMAINDER OF THE REGION. CONVECTIVE ELEMENTS STILL LOOK RESPECTABLE AND STILL CAN NOT RULE OUR THUNDER NOR SNOWFALL RATES OF 1-3 INCHES PER HOUR. REMAINDER OF THE DISCUSSION FOLLOWS... THIS NEAR TERM IS THAT PERCEIVED CALM BEFORE THE STORM. PER THE SATELLITE FOG PRODUCT /11U-3.9U IMAGERY/...STRATUS CONTINUES TO SLIDE SOUTHWARD WITH SOME BREAKS IN THE OVERCAST ACROSS THE DACKS AND MID HUDSON VALLEY. HOWEVER...THIS WILL BE REPLACED/COMBINED WITH APPROACH OF UPSTREAM STORM MOISTURE WITH THICKENING AND LOWERING OF THE CLOUD BASE. BASED ON THE HOURLY RUC AND HIRES EXPERIMENTAL RUC /HRRR/...IT SEEMS THE MORNING COMMUTE SHOULD BE PROBLEM FREE WITH RESPECT TO WEATHER AS THE SNOW SHOULD APPROACH THE CATSKILLS...WESTERN MOHAWK VALLEY SHORTLY AFTER 15Z /IE 10 AM EST/. TEMPERATURES WILL REMAIN NEARLY STEADY THROUGH THIS NEAR TERM AS THE ATMOSPHERIC COLUMN MOISTENS UP AND MINIMAL INSOLATION. && .SHORT TERM /10 AM THIS MORNING THROUGH 6 PM SATURDAY/... ...SIGNIFICANT SNOW STORM THIS AFTERNOON AND EVENING... PER THE H2O VAPOR LOOP AND UPSTREAM SOUNDINGS/OBSERVATIONS...AN IMPRESSIVE WAVE WITH EQUALLY IMPRESSIVE DYNAMICS AND TROPICAL MOISTURE INFLUX FROM THE EASTERN PACIFIC QUICKLY MOVING ACROSS THE CENTER OF THE NATION THIS MORNING. FIRST...LIGHTNING ACTIVITY REMAINS QUITE ACTIVE PER THE LIGHTNING DETECTION NETWORK FROM THE I80 CORRIDOR SOUTHWARD INTO THE MISSISSIPPI RIVER VALLEY. SECOND...WIND PROFILERS ACROSS THE PLAINS REVEAL 100+KT AT 500MB WITH GREATER THAN 50KTS AT 850MB FROM THE PLAINS INTO THE STATE OF ILLINOIS WITH AN DEPARTING...YET INCREASING...JET NORTH OF THE GREAT LAKES INTO NEW ENGLAND. THIS SEEMS TO BE SETTING UP A COUPLED JET STRUCTURE WHICH IS EXPECTED TO MOVE ACROSS THE PA/NY BORDER THIS AFTERNOON. THIRD...HIGH MOISTURE CONTENT UPSTREAM WITH IMPRESSIVE MID LEVEL LAPSE RATES HENCE THOSE LIGHTNING STRIKES...AND LIKELY MORE OCCURRING FROM CLOUD TO CLOUD. LASTLY...BASED ON RADAR AND SATELLITE TRENDS....THIS STORM IS MOVING SLIGHTLY MORE EAST- NORTHEAST THAN EAST AS TROUGH AXIS ACROSS QUEBEC CONTINUE TO LIFT QUICKLY NORTHEAST. THIS WOULD TREND THE HIGHER QPF FURTHER NORTH AND A MIXTURE OF SLEET FOR THE CATSKILLS...MID HUDSON VALLEY AND NORTHWEST CONNECTICUT. AS FOR SPECIFICS...GIVEN THE ABOVE PARAMETERS AND CROSS SECTIONS FROM NCEP MODEL SUITE SHOW IMPRESSIVE FRONTOGENESIS THIS AFTERNOON WITH DEEP NEGATIVE EPV...THIS ALL SUGGESTS THE STRONG FRONTOGENESIS BENEATH CONDITIONALLY UNSTABLE MID-LAYERS WILL CONTRIBUTE TO AT LEAST ISOLATED THUNDER SOUTHERN HALF OF THE CWA INTO THIS EVENING. WE WILL INCLUDE THE MENTION OF THUNDER AT THIS TIME. IN ADDITION...THOSE CROSS SECTIONS REVEAL THE MAX LIFT WILL BE OCCURRING WITHIN THE BEST DENDRITIC ICE GROWTH REGION SO DO EXPECT IMPRESSIVE HOURLY SNOWFALL RATES WHICH COULD APPROACH UP TO 3 INCHES PER HOUR AS SUGGESTED BY THE COBB TECHNIQUE /SLIGHTLY HIGHER INTO THE HIGHER TERRAIN WITH ADDED OROGRAPHIC LIFT/. HEAVY SNOW AND SLEET IS EXPECTED FOR THOSE SOUTHERN MOST COUNTIES IN THE CWA. WITH THE STORMS FURTHER NORTH TRACK EXPECTED...THIS WILL HAVE IMPLICATIONS FOR THE SOUTHERN ADIRONDACKS. WITH HIGHER SNOW RATIOS EXPECTED HERE...EXPECTING SNOWFALLS BETWEEN THAT 6 AND 10 RANGE. SO WE WILL EXPAND THE WARNING FURTHER NORTH. WITH THE FAST MOVEMENT OF THIS STORM...ACTIVITY WILL QUICKLY DIMINISH TOWARD MIDNIGHT. HOWEVER...MID LEVEL TROUGH AXIS AND VERY MOIST PROFILES BELOW THE 600-700MB AND AMPLE MECHANICAL MIXING AND SHEAR WITHIN THIS MOIST LAYER SHOULD KEEP LIGHT SNOW GOING FOR MOST OF THE NIGHT. THIS WILL NEED TO BE MONITOR CLOSELY AS WE MIGHT LOSE ICE NUCLEI POTENTIAL WHICH WOULD PROVIDE FREEZING DRIZZLE. EVENTUALLY...RIDGE AXIS AT THE SURFACE OOZES SOUTHWARD FROM ONTARIO AS HEIGHTS RISE ALOFT DURING SATURDAY FOR A MAINLY DRY DAY. STILL...AMPLE MOISTURE SEEMS TO BE TRAPPED BELOW THE SUBSIDENCE INVERSION WHICH MAY LIMIT SUNSHINE POTENTIAL AND WE COULD SEE A FLURRY OR TWO AROUND THE REGION. WILL HOLD ONTO SLIGHT CHANCE POPS AT THIS TIME FOR THE ENTIRE CWA. EXTENSIVE COLLABORATION WITH SPC/HPC AND SURROUNDING WFOS THIS MORNING...THANK YOU. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... THE STORMS GO MARCHING ON... SIGNIFICANT WINTER STORMS COULD IMPACT THE REGION AGAIN LATE SATURDAY NIGHT INTO SUNDAY NIGHT...AND AGAIN TUESDAY INTO THE FIRST PART OF CHRISTMAS DAY. A 500 HPA TROF ROTATES ACROSS THE REGION FROM THE WEST SATURDAY NIGHT INTO MONDAY MOVING A SURFACE LOW FROM THE SOUTHERN PLAINS SATURDAY MORNING TO THE OHIO VALLEY BY SATURDAY EVENING...TO THE CAROLINA COAST BY SUNDAY MORNING...WHERE IT RAPIDLY INTENSIFIES AND MOVES TO NEAR CAPE COD BY SUNDAY EVENING. WE HAVE LEFT THE LIKELY POPS FOR LATE SATURDAY NIGHT AND UPGRADED THE POPS FROM LIKELY TO CATEGORICAL FOR DURING THE DAY SUNDAY...THEN DROPPING THEM OFF SUNDAY NIGHT EXCEPT FOR THE WESTERN ADIRONDACKS WHERE SOME LAKE EFFECT WILL HANG ON. ASIDE FROM A BRIEF PERIOD OF SOME MIXING IN THE MID HUDSON REGION OF NY AND SOUTHERN LITCHFIELD COUNTY CT DURING THE MID AFTERNOON SUNDAY...THE P-TYPE OF THIS STORM WILL BE ALL SNOW. WE HAVE BEEN A BIT CONSERVATIVE ON THE FLUFF FACTOR WITH RATIOS MOSTLY AROUND 10 TO 1 FOR THE BULK OF THE PRECIP...WITH THE LIQUID PRECIP FROM AROUND 0.5 INCH IN THE WESTERN ADIRONDACKS TO JUST UNDER 0.9 INCH IN THE CATSKILLS... AND SNOW TOTALS OF 5 TO 10 INCHES. SOME OF THESE AMOUNTS ARE LIKELY TO INCREASE...ESPECIALLY WHERE THE TERRAIN BECOMES A FACTOR. ON MONDAY THAT STORM RAPIDLY LIFTS INTO THE MARITIMES AS HIGH PRESSURE MOVES FROM THE PLAINS INTO THE MID ATLANTIC STATES. ON TUESDAY THAT HIGH MOVES EAST INTO THE ATLANTIC TO BE FOLLOWED BY ANOTHER LOW WHICH MOVES FROM THE SOUTHERN ROCKIES ACROSS THE PLAINS TO THE MISSISSIPPI VALLEY BY WEDNESDAY MORNING...THEN TO OVER LONG ISLAND BY CHRISTMAS MORNING AND OUT TO SEA BY THE EVENING OF CHRISTMAS DAY. THE LATEST GFS IS A BIT SLOWER THAN HPC WHICH RUSHES THE LOW CENTER TO THE MARITIMES BY CHRISTMAS MORNING. FOR THE MOST PART HAVE POPULATED THE GRIDS WITH THE EVENING GMOS GUIDANCE. ASIDE FROM WEDNESDAY...WHEN THE HIGHS IN THE HUDSON VALLEY WILL BE IN THE 30S...TEMPERATURES WILL AVERAGE WELL BELOW SEASONAL NORMALS. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... FLIGHT CONDITIONS ACROSS THE FORECAST AREA VARIED EARLY THIS MORNING WITH AN MVFR CEILING AT KDDH...MVFR VISIBILITY DUE TO RADIATION FOG AT KPOU...AND VFR AT THE REST OF THE METAR SITES. FLIGHT CONDITIONS ARE FORECAST TO DETERIORATE SIGNIFICANTLY LATER THIS MORNING TO IFR AND THEN LIFR AS SNOW SPREADS FROM SOUTHWEST TO NORTHEAST ACROSS THE REGION. A STORM SYSTEM WILL MOVE QUICKLY FROM THE OHIO VALLEY TO ACROSS CENTRAL PA. THE SNOW SHOULD COME IN RATHER QUICKLY...SO CONDITIONS ARE LIKELY TO GO FROM VFR/MVFR TO IFR IN A SHORT PERIOD OF TIME. SNOW WILL THEN FALL HEAVILY AT TIMES THIS AFTERNOON WITH LIFR LIKELY AT ALL TERMINALS. WINDS WILL REMAIN RATHER LIGHT THROUGH FRI AFTN. SOME IMPROVEMENT WILL OCCUR LATER THIS EVENING AS THE STORM MOVES ON WITH THE SNOW LIGHTENING UP AND CLOUD BASES RISING SLIGHTLY. OUTLOOK... TONIGHT...IFR/MVFR. SN TAPERING TO -SHSN. SAT...VFR. NO SIG WX. SUN...IFR...CIG...LKLY SN/PL/FZRA/RA. MON...VFR..CHC -SHSN. TUE...VFR. && .HYDROLOGY... NO HYDRO PROBLEMS ARE EXPECTED FOR THE NEXT FIVE DAYS. WITH MAINLY FROZEN OR FREEZING PRECIPITATION FORECAST OVER THE NEXT SEVERAL DAYS...AND TEMPS GENERALLY AT OR BELOW FREEZING EVEN DURING THE DAYTIME PERIODS...EXPECT STREAMS AND RIVERS TO SLOWLY RETURN TO NEAR SEASONAL NORMAL LEVELS AND FLOWS OVER THE NEXT FEW DAYS AS RUNOFF DECREASES. WITH TEMPERATURES FORECAST AT OR BELOW FREEZING COULD SEE AN INCREASE IN ICE COVERAGE AND THICKNESS ON THE RIVERS ESPECIALLY IN COLDER REGIONS. FOR DETAILS ON THE RIVERS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...WINTER STORM WARNING FROM 9 AM THIS MORNING TO 1 AM EST SATURDAY FOR CTZ001-013. NY...WINTER STORM WARNING FROM 9 AM THIS MORNING TO 1 AM EST SATURDAY FOR NYZ032-033-038>043-047>054-058>061-063>066- 082>084. MA...WINTER STORM WARNING FROM 9 AM THIS MORNING TO 1 AM EST SATURDAY FOR MAZ001-025. VT...WINTER STORM WARNING FROM 9 AM THIS MORNING TO 1 AM EST SATURDAY FOR VTZ013>015. && $$ SYNOPSIS...BGM NEAR TERM...BGM SHORT TERM...BGM LONG TERM...RCK AVIATION...RCK HYDROLOGY...RCK FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT WWW.WEATHER.GOV/ALBANY ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 900 PM EST SAT DEC 20 2008 ...MUCH COLDER AND DRIER AIR ARRIVES ON SUNDAY ENDING STRETCH OF ABOVE NORMAL TEMPERATURES... ...SMALL CRAFT ADVISORY CONDITIONS EXPECTED ACROSS THE COASTAL WATERS BEHIND A STRONG COLD FRONT SUNDAY AFTERNOON INTO MONDAY... .UPDATE...LATEST WATER VAPOR/500 MB RUC ANALYSIS DEPICTS A PROGRESSIVE WEST TO EAST UPPER FLOW ACROSS THE LOWER 48...WITH A MEAN TROUGH OVER THE N/CNTRL STATES ANCHORED BY A UPPER LOW OVER THE DAKOTAS. SEVERAL WEAK IMPULSES ARE TRANSLATING EASTWARD AROUND THE PERIPHERY OF THIS TROUGH AND EJECTING ACROSS THE SOUTHERN STATES. FURTHER SOUTH...A BROAD RIDGE REMAINS THE DOMINANT FEATURE ACROSS THE GULF OF MEXICO AND NORTHWEST CARRIBEAN. THE 00Z REGIONAL SURFACE ANALYSIS SHOWS OUR CWFA SANDWICHED BETWEEN AN WEST-EAST RIDGE AXIS TO THE SOUTH AND A FRONTAL SYSTEM TO THE NORTH. LOW PRESSURE WAS GETTING ORGANIZED ALONG THIS FRONT OVER WESTERN KY WITH THE TRAILING COLD FRONT EXTENDING SOUTHWESTWARD INTO EASTERN TX. REGIONAL SATELLITE AND RADAR IMAGERY INDICATE MOST OF THE CLOUDINESS AND PCPN IS OCCURRING BEHIND THE FRONT. METAR REPORTS ALONG THE PANHANDLE COAST INDICATE AREAS OF SEA FOG WITH VSBYS BELOW 1/2SM FROM COASTAL WALTON COUNTY WESTWARD. HIGHEST SREF PROBS FOR LESS THAN 1SM VSBYS (50 PCT OR GREATER) ARE FORECAST FOR PORTIONS OF THE FL PANHANDLE AND I-75 CORRIDOR OF NORTHERN FL. FOG COVERAGE TONIGHT WILL BE MORE PATCHY AND NOT AS DENSE AS PREVIOUS NIGHTS (SEE AVIATION DISCUSSION BELOW FOR MORE DETAILS). TIMING OF THE SHOWERS SHOULD HOLD OFF UNTIL WELL AFTER MIDNIGHT ACROSS OUR NORTHWEST ZONES AS THE COLD FRONT APPROACHES. DO NOT FORESEE ANY REASONS TO JUSTIFY CHANGING THE GRIDS OR AFTERNOON ZONE FORECAST ATTM. && .AVIATION...VFR CIGS AT THE START OF THE TAF PERIOD WILL LOWER TO MVFR BY OR BEFORE 06Z. KTLH AND KVLD COULD SEE A PERIOD OF IFR CONDITIONS BEFORE COLD FRONTAL PASSAGE SUNDAY MORNING. THE FRONT WILL SWEEP ACROSS THE AREA FROM NW TO SE BETWEEN 12Z AND 18Z SUNDAY. NO TSRA ARE EXPECTED WITH THE FRONT...BUT SCATTERED SHOWERS ARE. CIGS WILL LIFT BACK TO VFR AFTER FROPA. WINDS WILL BE GUSTY OUT OF THE N-NW BEHIND THE FRONT WITH FREQUENT GUSTS OVER 20 KT. && .MARINE... THE GRADIENT BETWEEN HIGH PRESSURE CENTERED TO OUR SOUTHEAST AND A STALLED FRONTAL BOUNDARY TO OUR NORTH WILL RESULT IN A CONTINUED LIGHT SOUTHWEST FLOW AND LOW SEAS INTO THE EVENING HOURS. SOUTHWEST FLOW WILL BEGIN TO INCREASE OVERNIGHT AHEAD OF A COLD FRONT THAT WILL CROSS THROUGH THE FORECAST WATERS SUNDAY MORNING AND EARLY AFTERNOON. EXPECT WINDS TO SHIFT AROUND TO THE NORTHWEST AND NORTH BEHIND THIS FRONT TO ADVISORY LEVELS BY LATER SUNDAY AND CONTINUE INTO AT LEAST MONDAY MORNING. HIGH PRESSURE THEN MOVES TO OUR NORTHEAST THROUGH THE MID WEEK PERIOD VEERING OUR WINDS AROUND TO THE EAST AND SOUTHEAST. THE GRADIENT IS EXPECT TO REMAIN TIGHT THROUGH TUESDAY NIGHT KEEPING WINDS AND SEAS ELEVATED. && .FIRE WEATHER...NO FIRE WEATHER CONCERNS UNTIL MONDAY WHEN MUCH DRIER AIR WILL CAUSE LONG DURATIONS OF LOW RELATIVE HUMIDITY REGION-WIDE. && .HYDROLOGY...RIVERS STILL EXPERIENCING HIGH FLOW/LEVELS FROM THE HEAVY RAINFALL ON DEC 10-11 ARE THE OCHLOCKONEE...THE APALACHICOLA ...AND THE CHOCTAWHATCHEE. ALONG THE OCHLOCKNEE RIVER...LEVELS CONTINUE TO SLOWLY FALL NORTH OF THE LAKE TALQUIN DAM. THE HAVANA AND THOMASVILLE GAUGES REMAIN AT ACTION STAGE...WITH CONCORD FALLING BELOW FLOOD STAGE LATER THIS EVENING. ALONG THE APALACHICOLA RIVER...THE BLOUNTSTOWN GAUGE IS DECLINING RAPIDLY THROUGH THE ACTION STAGE. ON THE CHOCTAWHATCHEE RIVER NEAR BRUCE...THE LEVEL IS ABOUT A HALF FOOT ABOVE FLOOD STAGE...BUT FALLING STEADILY AND PROJECTED TO BE BELOW 13 FEET SUNDAY AFTERNOON. RAINFALL ACCUMULATIONS ON SUNDAY SHOULD HAVE LITTLE TO NO IMPACT ON AREA RIVERS. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 59 63 33 53 30 / 10 50 0 0 0 PANAMA CITY 61 64 34 53 39 / 10 50 0 0 0 DOTHAN 57 58 30 50 34 / 40 60 0 0 0 ALBANY 59 61 30 51 29 / 30 60 0 0 0 VALDOSTA 59 64 32 52 31 / 10 50 0 0 0 CROSS CITY 58 70 36 56 32 / 10 30 10 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY AFTERNOON FOR THE FOLLOWING ZONES: COFFEE...DALE...GENEVA...HENRY... HOUSTON. GA...FIRE WEATHER WATCH MONDAY AFTERNOON FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN...BROOKS...CALHOUN...CLAY... COLQUITT...COOK...DECATUR...DOUGHERTY...EARLY...GRADY... IRWIN...LANIER...LEE...LOWNDES...MILLER...MITCHELL... QUITMAN...RANDOLPH...SEMINOLE...TERRELL...THOMAS...TIFT... TURNER...WORTH. FL...FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING FOR THE FOLLOWING ZONES: BAY...CALHOUN...DIXIE...FRANKLIN... GADSDEN...GULF...HOLMES...INLAND WALTON...JACKSON... JEFFERSON...LAFAYETTE...LEON...LIBERTY...MADISON...TAYLOR... WAKULLA...WASHINGTON. GM...SMALL CRAFT ADVISORY IN EFFECT FROM 12 PM EST SUNDAY TO 12 PM EST MONDAY ALL MARINE LEGS. && $$ JAMSKI/WOOL fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 320 PM EST SAT DEC 20 2008 ...MUCH COLDER AIRMASS ARRIVES DURING SUNDAY TO END THE CURRENT STRETCH OF UNSEASONABLY WARM TEMPERATURES... ...SMALL CRAFT ADVISORY CONDITIONS EXPECTED ACROSS THE COASTAL WATERS BEHIND A STRONG COLD FRONT SUNDAY AFTERNOON INTO MONDAY... .SYNOPSIS... 20Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING A FAST NORTHERN STREAM FLOW ACROSS THE CONUS. THE NORTHERN STREAM IS CARVING OUT A MEAN TROUGH ACROSS THE WESTERN/CENTRAL STATES ANCHORED BY A LARGE UPPER LOW SPINNING OVER THE DAKOTAS. A SERIES OF WEAK IMPULSES ARE RIDING THE FLOW AROUND THE PERIPHERY OF THIS TROUGH AND EJECTING ACROSS THE SOUTHERN PLAINS. FLOW THEN BECOMES MORE ZONAL IN NATURE FURTHER DOWNSTREAM TOWARD THE EASTERN SEABOARD IN THE WAKE OF A NOW STRONG OCEAN STORM THAT BROUGHT ALL THE SNOW AND ICE TO THE NORTHEASTERN STATES/MIDWEST ON FRIDAY. FURTHER TO THE SOUTH WE STILL FIND OUR LARGE AND DOMINANT RIDGE IN PLACE ACROSS THE GULF OF MEXICO AND NORTHWEST CARRIBEAN. OUR FORECAST AREA RESIDES UNDER THE NORTHERN PERIPHERY OF THIS RIDGE AND IS ENJOYING ONE MORE DAY OF UNSEASONABLY WARM TEMPERATURES BEFORE A MUCH COLDER AIRMASS ARRIVES DURING SUNDAY. AT THE SURFACE...RIDGING IS FOUND ACROSS THE AREA WITH THE HIGH CENTERED TO OUR SE IN THE VICINITY OF TAMPA FLORIDA. ANALYSIS ALSO SHOWING A WEAK FRONTAL BOUNDARY TO OUR NORTH ACROSS NORTHERN AL/MS. THE GRADIENT BETWEEN THESE TWO FEATURES IS RESULTING IN A MOIST LOW LEVEL SOUTHWESTERLY FLOW. MOSTLY CLOUDY SKIES ACROSS THE AREA THIS AFTERNOON WITH PERIODIC BREAK OF SUN. TEMPERATURES REGION-WIDE IN THE LOWER TO MIDDLE 70S. .SHORT TERM (TONIGHT THROUGH MONDAY NIGHT)... SURFACE LOW PRESSURE OVER ARKANSAS WILL MOVE EAST TO THE TN VALLEY THIS EVENING. AT THE SAME TIME...WILL BE WATCHING A COLD FRONT TRAILING FROM THIS LOW CENTER MOVING SOUTH INTO THE LOWER MS VALLEY AND NORTHERN ALABAMA. AS THE LARGE MID-LEVEL TROUGH OVER THE MID-SECTION OF THE COUNTRY MOVES EAST TO THE GREAT LAKES/OH VALLEY OVERNIGHT...THE TN VALLEY LOW WILL TRANSFER ITS ENERGY TO THE MID-ATLANTIC COAST AND BEGIN TO RAPIDLY INTENSIFY EARLY SUNDAY MORNING. AS THIS OCCURS THE ASSOCIATED SURFACE COLD FRONT STILL TO OUR NORTH WILL STRENGTHEN AND DIVE SOUTHEAST INTO THE FORECAST AREA. THIS SHOULD BE A QUICK MOVING FRONT AS STRONG SURFACE HIGH PRESSURE BUILDS INTO THE CENTRAL PLAINS FROM CANADA AND PROVIDES A SIGNIFICANT SOUTHWARD PUSH. THE FRONT IS PROGGED TO CROSS THE NW HALF OF THE AREA SUNDAY MORNING AND THEN EXIT TO THE SOUTHEAST OF THE FLORIDA BIG BEND DURING THE MIDDLE AFTERNOON. RAIN CHANCE PHILOSOPHY HAS CHANGED LITTLE FROM THE PREVIOUS GUIDANCE PACKAGE. STILL EXPECTING A THINNING BAND OF SHOWERS ALONG AND AHEAD OF THIS FRONT AS NARROWING CORRIDOR OF 925-850MB THETA-E ADVECTION OVERSPREADS THE AREA. A FEW OF THESE SHOWERS MAY REACH OUR NW ZONES ACROSS SE AL/SW GA LATE TONIGHT...HOWEVER MOST OF THE ACTIVITY WILL BE OCCURRING DURING THE DAYLIGHT MORNING HOURS AND EARLY AFTERNOON. THE OVERALL IMPACT OF THE SHOWERS TO OUTDOOR ACTIVITIES APPEARS LIMITED AS THEIR DURATION SHOULD BE BRIEF AND RESULT GENERALLY IN ONLY AROUND ONE TENTH OF AN INCH OR LESS OF ACCUMULATION. A RUMBLE OF THUNDER IS NOT OUT OF THE QUESTION FROM DOTHAN TO ALBANY AND NORTHWARD EARLY TOMORROW MORNING...HOWEVER WITH VERY LIMITED MID/UPPER LEVEL DYNAMICS TO PROVIDE ADDITIONAL SYNOPTIC LIFT...THE SUPPORT FOR DEEP CONVECTION APPEARS SMALL. MUCH COLDER AIRMASS RAPIDLY FILTERS INTO THE REGION BEHIND THIS FRONT SUNDAY EVENING AND NIGHT AS SKIES CLEAR FROM NORTHWEST TO SOUTHEAST. ALL ZONES WILL FEEL THE DIFFERENCE IN AIRMASS BY THE TIME THE SUN SETS SUNDAY EVENING AS TEMPERATURES FALL THROUGH THE 40S AND 30S WITH A BRISK NORTH WIND. OUR NORTHERN AND WESTERN ZONES MAY EVEN SEE AN HOUR OR TWO AT OR JUST BELOW FREEZING LATE SUNDAY NIGHT AND MONDAY MORNING...HOWEVER WITH DEWPOINT DEPRESSIONS AT THE SURFACE IN THE 10-15+ DEGREE RANGE AND WITH A STEADY BREEZE...FROST FORMATION APPEARS HIGHLY UNLIKELY. MONDAY AND MONDAY NIGHT...STRONG SURFACE HIGH PRESSURE PASSING TO OUR NORTH WILL PROVIDE A PERIOD OF DRY WEATHER...BUT BELOW NORMAL TEMPERATURES TO START THE WORK WEEK. 850MB TEMPERATURES DURING THE DAY MONDAY WILL RANGE FROM AROUND 0 AT OUR NORTHERN BORDERS TO AROUND 5C AT THE COAST. WHILE THE AIRMASS POTENTIAL THIS TIME OF YEAR FOR THESE TEMPERATURES UNDER MOSTLY SUNNY SKIES WOULD BE IN THE MIDDLE 50S TO LOWER 60S...CONTINUED COLD AIR ADVECTION FROM THE NORTH WILL PREVENT THESE POTENTIALS FROM BEING REACHED. HIGH TEMPERATURES ARE LIKELY TO STRUGGLE INTO THE LOWER 50S NORTH AND THE MIDDLE 50S SOUTH DESPITE THE SUNSHINE. THE HIGH CENTER MOVES TO THE MID-ATLANTIC COAST MONDAY NIGHT VEERING OUR WINDS AROUND TO THE EAST. A BIT SUSPICIOUS OF THE VERY COLD MAV NUMBERS (MIDDLE AND UPPER 20S) FOR MONDAY NIGHT AT PLACES LIKE KTLH AND KABY. THESE VALUES WOULD BE MORE LIKELY IF THE HIGH CENTER WERE IN THE VICINITY PROVIDING AN IDEAL RADIATIONAL COOLING SETUP. HOWEVER...WITH THE FORECAST POSITION WELL TO THE NORTHEAST...WOULD EXPECT THE GRADIENT TO REMAIN A BIT TOO STRONG AND WILL ADD A FEW DEGREES KEEPING THE COLDEST LOCATIONS RIGHT AROUND 29/30 F FOR NOW. && .LONG TERM...(TUESDAY-FRIDAY) AFTER A COOL AND DRY START TO THE EXTENDED FORECAST TUESDAY MORNING...TEMPERATURES WILL MODERATE QUICKLY BACK TO ABOVE NORMAL WEDNESDAY THROUGH FRIDAY. HOWEVER...THE MODELS ARE STILL SHOWING QUITE A BIT OF DIFFERENCES THROUGH THIS PERIOD AND CONTINUE TO JUMP BACK AND FORTH WITH THE PROGRESSION OF THE NEXT SHORTWAVE/COLD FRONT THAT IS PROGGED TO APPROACH THE REGION FROM THE WEST TUESDAY THROUGH THURSDAY. THEREFORE...FORECAST UNCERTAINTY REMAINS HIGH AROUND CHRISTMAS DAY. GFS/ECMWF ARE NOW HANGING THE WEAK COLD FRONT UP JUST NORTHWEST OF THE LOCAL FORECAST AREA WEDNESDAY NIGHT THROUGH FRIDAY WITH THE RIDGE AXIS REMAINING IN PLACE ALONG THE GULF COAST (VERY SIMILAR TO THE CURRENT WARM PATTERN). && .AVIATION... VFR CONDITIONS RETURNED BRIEFLY TO MOST AREAS BY EARLY AFTERNOON... WITH THE EXCEPTION OF PERSISTENT AREAS OF FOG ALONG THE COAST AND OVER THE ADJACENT COASTAL WATERS. THE RETURN TO VFR CEILINGS AND VISIBILITIES WILL BE SHORT-LIVED...AS THE AIRMASS REMAINS VERY MOIST AT THE LOWER LEVELS...WITH A SOUTH TO SOUTHWEST FLOW COMING OFF THE GULF ACROSS RELATIVELY COOLER NEAR SHORE WATERS. EXPECT A RAPID RETURN TO WIDESPREAD MVFR CEILINGS AND VISIBILITIES ACROSS THE TRI-STATE AREA THIS EVENING...WITH WIDESPREAD IFR CEILINGS AND LOCAL IFR VISIBILITIES DEVELOPING LATER TONIGHT... ESPECIALLY ACROSS FLORIDA. A COLD FRONT WILL APPROACH FROM THE NORTHWEST EARLY SUNDAY...ACCOMPANIED BY THAT WILL SPREAD INTO SOUTHEAST ALABAMA BY SUNRISE...AND EASTWARD TO THE REST OF THE AREA BY SUNDAY AFTERNOON. WINDS WILL REMAIN SOUTHWEST 5 TO 10 KNOTS AHEAD OF THE FRONT TONIGHT...AND SHIFT TO NORTHWEST 10 TO 15 KNOTS FOLLOWING THE PASSAGE OF THE FRONT ON SUNDAY. && .MARINE... THE GRADIENT BETWEEN HIGH PRESSURE CENTERED TO OUR SOUTHEAST AND A STALLED FRONTAL BOUNDARY TO OUR NORTH WILL RESULT IN A CONTINUED LIGHT SOUTHWEST FLOW AND LOW SEAS INTO THE EVENING HOURS. SOUTHWEST FLOW WILL BEGIN TO INCREASE OVERNIGHT AHEAD OF A COLD FRONT THAT WILL CROSS THROUGH THE FORECAST WATERS SUNDAY MORNING AND EARLY AFTERNOON. EXPECT WINDS TO SHIFT AROUND TO THE NORTHWEST AND NORTH BEHIND THIS FRONT TO ADVISORY LEVELS BY LATER SUNDAY AND CONTINUE INTO AT LEAST MONDAY MORNING. HIGH PRESSURE THEN MOVES TO OUR NORTHEAST THROUGH THE MID WEEK PERIOD VEERING OUR WINDS AROUND TO THE EAST AND SOUTHEAST. THE GRADIENT IS EXPECT TO REMAIN TIGHT THROUGH TUESDAY NIGHT KEEPING WINDS AND SEAS ELEVATED. && .FIRE WEATHER...WITH LITTLE CHANGE IN THE VERY MOIST LOW LEVEL AIRMASS THERE ARE NO FIRE WEATHER CONCERNS UNTIL MONDAY. A COLD FRONT WILL PUSH EASTWARD ACROSS THE AREA ON SUNDAY...BRINGING A TEMPORARY SURGE OF MUCH COLDER DRIER AIR. DURATIONS OF LOW RELATIVE HUMIDITY ARE LIKELY TO MEET CRITICAL LEVELS ON MONDAY AFTERNOON...AND A FIRE WEATHER WATCH WILL BE ISSUED FOR THE TRI-STATE AREA FOR MONDAY. && .HYDROLOGY... STILL EXPERIENCING LOCALIZED RIVER PROBLEMS ACROSS THE AREA IN THE WAKE OF LAST WEEKS HEAVY RAINFALL. MOST NOTABLE RIVERS STILL EXPERIENCING HIGH FLOW/LEVELS INCLUDE THE OCHLOCKONEE RIVER...THE APALACHICOLA RIVER...AND THE CHOCTAWHATCHEE RIVER. ALONG THE OCHLOCKNEE RIVER LEVELS CONTINUE TO SLOWLY DECLINE TO THE NORTH OF THE LAKE TALQUIN DAM. HAVANA AND MIDWAY GAUGES ARE CURRENTLY IN ACTION STAGE WITH CONCORD STILL JUST ABOVE FLOOD STAGE. ALONG THE APALACHICOLA RIVER THE BLOUNTSTOWN GAUGE IS DECLINING RAPIDLY THROUGH THE ACTION STAGE LEVEL HAVING DROPPED BELOW FLOOD STAGE FRIDAY EVENING. FINALLY FURTHEST WEST ALONG THE CHOCTAWHATCHEE RIVER WE FIND STAGES ALSO FALLING. CARYVILLE GAUGE DROPPED BELOW FLOOD STAGE ON THURSDAY EVENING AND WILL DROP BELOW ACTION STAGE EARLY THIS EVENING. FURTHER DOWN RIVER AT THE BRUCE GAUGE WE ARE STILL FINDING SOME MINOR PROBLEMS. THE RIVER LEVEL IS FALLING AND HAS RECENTLY CROSSING THROUGH 14 FEET (OUT OF MODERATE FLOODING STAGE AND INTO MINOR FLOODING STAGE). A COLD FRONT WILL BRING A NARROW BAND OF SHOWERS ACROSS THE AREA SUNDAY. THESE SHOWERS LOOK TO BE ON THE LIGHT SIDE WITH RAINFALL ACCUMULATIONS WHICH SHOULD HAVE LITTLE TO NO IMPACT ON AREA RIVERS. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 59 63 33 53 30 / 10 50 0 0 0 PANAMA CITY 61 64 34 53 39 / 10 50 0 0 0 DOTHAN 57 58 30 50 34 / 40 60 0 0 0 ALBANY 59 61 30 51 29 / 30 60 0 0 0 VALDOSTA 59 64 32 52 31 / 10 50 0 0 0 CROSS CITY 58 70 36 56 32 / 10 30 10 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY AFTERNOON FOR THE FOLLOWING ZONES: COFFEE...DALE...GENEVA...HENRY... HOUSTON. GA...FIRE WEATHER WATCH MONDAY AFTERNOON FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN...BROOKS...CALHOUN...CLAY... COLQUITT...COOK...DECATUR...DOUGHERTY...EARLY...GRADY... IRWIN...LANIER...LEE...LOWNDES...MILLER...MITCHELL... QUITMAN...RANDOLPH...SEMINOLE...TERRELL...THOMAS...TIFT... TURNER...WORTH. FL...FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING FOR THE FOLLOWING ZONES: BAY...CALHOUN...DIXIE...FRANKLIN... GADSDEN...GULF...HOLMES...INLAND WALTON...JACKSON... JEFFERSON...LAFAYETTE...LEON...LIBERTY...MADISON...TAYLOR... WAKULLA...WASHINGTON. GM...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/HYDROLOGY...MROCZKA AVIATION/FIRE WEATHER...DUVAL LONG TERM...GIBBS fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 1000 AM EST SAT DEC 20 2008 .SYNOPSIS/DISCUSSION... 14Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING A FAST NORTHERN STREAM FLOW ACROSS THE CONUS THIS MORNING. THE NORTHERN STREAM IS CARVING OUT A MEAN TROUGH ACROSS THE WESTERN/CENTRAL STATES ANCHORED BY A LARGE UPPER LOW SPINNING OVER THE DAKOTAS. A SERIES OF WEAK IMPULSES ARE RIDING THE FLOW AROUND THE PERIPHERY OF THIS TROUGH AND EJECTING ACROSS THE SOUTHERN PLAINS. FLOW THEN BECOMES MORE ZONAL IN NATURE FURTHER DOWNSTREAM TOWARD THE EASTERN SEABOARD IN THE WAKE OF A NOW STRONG OCEAN STORM THAT BROUGHT ALL THE SNOW AND ICE TO THE NORTHEASTERN STATES/MIDWEST ON FRIDAY. FURTHER TO THE SOUTH WE STILL FIND OUR LARGE AND DOMINANT RIDGE IN PLACE ACROSS THE GULF OF MEXICO AND NORTHWEST CARRIBEAN. OUR FORECAST AREA RESIDES UNDER THE NORTHERN PERIPHERY OF THIS RIDGE AND WILL ENJOY ONE MORE DAY OF UNSEASONABLY WARM TEMPERATURES BEFORE THE REALITY OF THE SEASON ARRIVES FOR THE FIRST PART OF NEXT WEEK. AT THE SURFACE...RIDGING IS FOUND ACROSS THE AREA WITH THE HIGH CENTERED TO OUR SE IN THE VICINITY OF TAMPA FLORIDA. ANALYSIS ALSO SHOWING A WEAK FRONTAL BOUNDARY TO OUR NORTH ACROSS NORTHERN AL/MS. THE GRADIENT BETWEEN THESE TWO FEATURES IS RESULTING IN A MOIST LOW LEVEL SOUTHWESTERLY FLOW. AREAS OF LOW STRATUS (~1000FT BASES) ARE EVIDENT ON THE FIRST EARLY MORNING VISIBLE SAT IMAGES. THE MOISTURE TO SUPPORT THIS STRATUS IS SHOWN CLEARLY ON THE 12Z KTLH SOUNDING WHICH HAS A NEARLY SATURATED PROFILE BELOW AROUND 850MB. HOWEVER...ABOVE AROUND 4-5KFT THE PROFILE BECOMES VERY DRY AS OUR ATMOSPHERE COMES UNDER THE INFLUENCE OF THE MID/UPPER LEVEL RIDGING OVER THE GULF. THIS PROFILE SUGGEST THAT IT MAY BE A SLOW PROCESS THIS MORNING TO MIX OUT THE LOW CLOUDS (ESPECIALLY SINCE WE ARE AT AN ANNUAL MINIMUM FOR SOLAR INSOLATION)...HOWEVER WE SHOULD BE ABLE TO GET THE SUN OUT (MIXED WITH SOME SCT CU) FOR THE AFTERNOON. THE MOIST LOW LEVEL FLOW WITH DEWPOINT IN THE MIDDLE/UPPER 60S IS RESULTING IN AREAS OF FOG ACROSS THE NEARSHORE COASTAL WATERS AND ALONG THE COASTAL ZONES THIS MORNING. THIS FOG IS LOCALLY DENSE IN SPOTS AS WELL...MAINLY ALONG THE FRANKLIN COUNTY COAST AND EASTWARD WHERE THE COOLEST SHELF WATERS IN APALACHEE BAY REACT WITH THE WARM AND MOIST FLOW. WILL LEAVE THE MARINE DENSE FOG ADVISORY IN EFFECT FOR THE REMAINDER OF THE MORNING AND RE-EVALUATE THE SITUATION TOWARD MIDDAY. ONCE THE EARLY LOW CLOUDS/FOG BURN OFF WILL BE LOOKING AT A PARTLY SUNNY AFTERNOON WITH HIGH TEMPERATURES AGAIN WELL ABOVE NORMAL IN THE MIDDLE 70S AWAY FROM THE IMMEDIATE COAST. AS MENTIONED ABOVE THOUGH...TODAY WILL BE THE END TO THIS PARTICULAR STREAK OF UNSEASONABLE TEMPERATURES. WILL BE WATCHING A COLD FRONT APPROACH FROM THE NORTHWEST TONIGHT AS LOW PRESSURE DEVELOPS RAPIDLY OFF THE MID-ATLANTIC COAST. THIS COLD FRONT IS PROGGED TO CROSS THE NW HALF OF THE AREA SUNDAY MORNING AND THEN EXIT TO THE SOUTHEAST OF THE FLORIDA BIG BEND DURING THE MID/LATE AFTERNOON. WILL BE WATCHING A THINNING BAND OF SHOWERS ALONG AND AHEAD OF THIS FRONT AS NARROWING CORRIDOR OF 925-850MB THETA-E ADVECTION OVERSPREADS THE AREA. A FEW OF THESE SHOWERS MAY REACH OUR NW ZONES ACROSS SE AL/SW GA LATE TONIGHT...HOWEVER MOST OF THE ACTIVITY WILL BE OCCURRING DURING THE DAYLIGHT MORNING HOURS INTO THE EARLY AFTERNOON. THESE SHOWERS SHOULD HAVE A LIMITED IMPACT TO OUTDOOR ACTIVITIES AS THEIR DURATION SHOULD BE BRIEF AND RESULT GENERALLY IN ONLY AROUND ONE TENTH OF AN INCH OF RAINFALL...IF NOT LESS. MUCH COLDER AIRMASS RAPIDLY FILTERS INTO THE REGION BEHIND THIS FRONT LATER SUNDAY AND SUNDAY NIGHT AS SKIES CLEAR FROM NORTHWEST TO SOUTHEAST. ALL ZONES WILL FEEL THE DIFFERENCE IN AIRMASS BY THE TIME THE SUN SETS SUNDAY EVENING AS TEMPERATURES FALL THROUGH THE 40S AND 30S WITH A BRISK NORTH WIND. OUR NORTHERN AND WESTERN ZONES MAY EVEN SEE AN HOUR OR TWO NEAR OR JUST BELOW FREEZING TOWARD SUNRISE MONDAY MORNING...HOWEVER WITH DEWPOINT DEPRESSIONS AT THE SURFACE BY THIS TIME IN THE 10-15 DEGREE RANGE AND A STEADY BREEZE...FROST FORMATION LOOKS HIGHLY UNLIKELY. && .AVIATION... A SMALL INCREASE IN LOW LEVEL WINDS THIS MORNING HAS HELPED TO LIMIT THE DEVELOPMENT OF IFR VISIBILITIES IN FOG ACROSS INLAND AREAS... WHILE MORE WIDESPREAD IFR TO MVFR VISIBILITIES PERSIST OVER THE COOLER COASTAL WATERS AND ADJACENT COAST. WITH LITTLE CHANGE IN THE OVERALL PATTERN OR AIRMASS...WILL SEE ONLY SLOW IMPROVEMENT AGAIN THROUGH THE REST OF THE MORNING INTO THE AFTERNOON HOURS...WITH IFR CEILINGS AND VISIBILITIES LIFTING BY LATE MORNING AND MVFR CEILINGS GRADUALLY SCATTERING OUT MOST AREAS BY EARLY TO MID AFTERNOON. HOWEVER... EXPECT A REPEAT OF WIDESPREAD MVFR TO IFR CEILINGS AND VISIBILITIES AGAIN LATER TONIGHT AND SUNDAY MORNING...ESPECIALLY ACROSS FLORIDA. ON SUNDAY A FRONT...CURRENTLY LOCATED WELL TO THE NORTHWEST OF THE TRI-STATE AREA...WILL BEGIN TO MOVE SOUTHWARD... BRINGING AN INCREASING CHANCE OF RAIN TO SOUTHEAST ALABAMA BY SUNDAY MORNING...AND THE REST OF THE AREA BY SUNDAY AFTERNOON... BEFORE EXITING TO THE SOUTHEAST SUNDAY EVENING. && .MARINE... THE GRADIENT BETWEEN HIGH PRESSURE CENTERED TO OUR SOUTHEAST AND A STALLED FRONTAL BOUNDARY TO OUR NORTH WILL RESULT IN A CONTINUED LIGHT SOUTHWEST FLOW AND LOW SEAS THROUGH THE DAYLIGHT HOURS. SOUTHWEST FLOW WILL BEGIN TO INCREASE TONIGHT AHEAD OF A COLD FRONT THAT WILL CROSS THROUGH THE FORECAST WATERS DURING SUNDAY. EXPECT WINDS TO SHIFT AROUND TO THE NORTHWEST AND NORTH BEHIND THIS FRONT TO ADVISORY LEVELS LATE SUNDAY INTO MONDAY MORNING. HIGH PRESSURE THEN MOVES TO OUR NORTHEAST THROUGH THE MID WEEK PERIOD VEERING OUR WINDS AROUND TO THE EAST AND SOUTHEAST. THE GRADIENT IS EXPECT TO REMAIN TIGHT THROUGH AT LEAST TUESDAY KEEPING WINDS AND SEAS ELEVATED NEAR CAUTIONARY LEVELS. AREAS OF SEA FOG CONTINUE ACROSS THE NEAR SHORE WATERS WITH THE MOST WIDESPREAD AND DENSE FOG ACROSS THE WATERS ALONG THE FRANKLIN COUNTY COAST AND EASTWARD. A MARINE DENSE FOG ADVISORY REMAINS IN EFFECT AND WILL RE-EVALUATE THE SITUATION AROUND MIDDAY WHEN THE FOG MAY HAVE A TENDENCY TO THIN OR LIFT. && .HYDROLOGY... STILL SEEING SOME SPOTTY RIVER PROBLEMS ACROSS THE AREA IN THE WAKE OF LAST WEEKS HEAVY RAINFALL. MOST NOTABLE RIVERS STILL EXPERIENCING HIGH FLOW/LEVELS INCLUDE THE OCHLOCKONEE RIVER...THE APALACHICOLA RIVER...AND THE CHOCTAWHATCHEE RIVER. ALONG THE OCHLOCKNEE RIVER LEVELS CONTINUE TO SLOWLY DECLINE TO THE NORTH OF THE LAKE TALQUIN DAM. HAVANA AND MIDWAY GAUGES ARE CURRENTLY IN ACTION STAGE WITH CONCORD STILL JUST ABOVE FLOOD STAGE. ALONG THE APALACHICOLA RIVER THE BLOUNTSTOWN GAUGE IS DECLINING RAPIDLY THROUGH THE ACTION STAGE LEVEL HAVING DROPPED BELOW FLOOD STAGE FRIDAY EVENING. FINALLY FURTHEST WEST ALONG THE CHOCTAWHATCHEE RIVER WE FIND STAGES ALSO FALLING. CARYVILLE GAUGE DROPPED BELOW FLOOD STAGE ON THURSDAY EVENING AND IS FORECAST TO DROP BELOW ACTION STAGE THIS AFTERNOON OR EVENING. FURTHER DOWN RIVER AT THE BRUCE GAUGE WE ARE STILL FINDING SOME MINOR PROBLEMS. THE RIVER LEVEL IS FALLING AND WAS CROSSING THROUGH 14 FEET THIS MORNING (OUT OF MODERATE FLOODING STAGE AND INTO MINOR FLOODING STAGE). A COLD FRONT IS ANTICIPATED TO BRING A BAND OF SHOWERS ACROSS THE AREA SUNDAY. THESE SHOWERS LOOK TO BE ON THE LIGHT SIDE WITH RAINFALL ACCUMULATIONS WHICH SHOULD HAVE LITTLE TO NO IMPACT ON AREA RIVERS. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 76 55 63 32 / 0 10 50 0 PANAMA CITY 73 60 65 34 / 0 10 50 0 DOTHAN 76 53 58 30 / 10 30 60 0 ALBANY 77 55 59 30 / 10 20 60 0 VALDOSTA 76 54 63 31 / 0 10 40 10 CROSS CITY 77 53 72 36 / 0 10 30 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...DENSE FOG ADVISORY FOR COASTAL COUNTIES THROUGH MORNING. GM...DENSE FOG ADVISORY FOR THE NEAR SHORE WATERS OUT TO 20NM FROM DESTIN FLORIDA TO THE MOUTH OF THE SUWANNEE RIVER INTO MIDDAY TODAY. && $$ SYNOPSIS/DISCUSSION/MARINE/HYDROLOGY...MROCZKA AVIATION...DUVAL fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 912 PM EST FRI DEC 19 2008 .DISCUSSION...AT THE RISK OF SOUNDING LIKE A BROKEN RECORD, THE MAIN FORECAST CONCERN THIS EVENING IS ONCE AGAIN FOG POTENTIAL. CONDENSATION PRESSURE DEFICIT CHARTS, SREF PROBABILITIES AND MOS ALL POINT TO A WIDESPREAD DENSE FOG EVENT DEVELOPING OVERNIGHT. ONCE DIFFERENCE TONIGHT IS THAT WE HAVE A BIT MORE WIND. HOWEVER, BASED ON SEVERAL RESEARCH STUDIES OF THE LOCAL AREA, WINDS ARE NOT EXPECTED TO BE HIGH ENOUGHT TO PREVENT AN ADVECTION FOG EVENT. WE ARE ALREADY SEEING LOW STRATUS/FOG NOSING NEWD ACROSS PORTIONS OF THE FL BIG BEND. A LOOK OUT THE E WINDOW OF THE OFFICE CONFIRMS THAT THIS IS FOG, RATHER THAN STRATUS. TD DEPRESSION ARE NEAR ZERO AND T AND TD ARE BOTH DROPPING TOWARD THE SHELF WATER SSTS. FOR THESE REASONS, WILL GET AHEAD OF THE GAME AND ISSUE A DENSE FOG ADVISORY FOR LAND AREAS TO GO WITH THE EXISTING ADVISORY OVER THE COASTAL WATERS. && .MARINE... DENSE FOG ADVISORY REMAINS IN EFFECT FOR THE NEAR SHORE WATERS DURING THE SECOND HALF OF TONIGHT INTO SAT MORNING. BEST CHANCES FOR THE MOST WIDESPREAD FOG AND LOWEST VISIBILITIES WILL BE ACROSS THE WATERS ADJACENT TO GULF COUNTY AND EASTWARD. HIGH PRESSURE IN CONTROL OF THE MARINE AREA WILL CONTINUE TO PROVIDE A GENERALLY LIGHT SOUTH FLOW WITH LOW SEAS INTO TONIGHT. THE RIDGE OF HIGH PRESSURE WILL SLIDE A BIT FURTHER SOUTH AND EAST INTO SATURDAY ALLOWING WINDS TO COME AROUND TO THE SOUTHWEST WITH TIME. MAIN CONCERN WILL REMAIN THE EXPECTED RE-DEVELOPMENT OF MAINLY NEAR SHORE FOG. THIS FOG IS LIKELY TO BECOME LOCALLY DENSE...ESPECIALLY ALONG THE COASTS OF GULF... FRANKLIN...WAKULLA AND TAYLOR COUNTIES...AND MAY LINGER THROUGH MUCH OF SATURDAY MORNING. WINDS AND SEAS SHOULD NOT SHOW A SIGNIFICANT INCREASE TOWARD CAUTIONARY LEVELS UNTIL THE APPROACH AND PASSAGE OF A COLD FRONT DURING SATURDAY NIGHT AND SUNDAY. A PERIOD OF ADVISORY LEVEL WINDS FROM THE NORTHWEST AND NORTH ARE BECOMING MORE LIKELY BEHIND THIS FRONT FOR SUNDAY AFTERNOON INTO MONDAY. && .AVIATION...FOG IS WAITING ALONG THE COAST TO POUNCE INLAND AFTER SUNSET. EXPECTY VERY HEAVY ADVECTION FOG TONIGHT. FOG ARRIVAL TIME WILL BE SLIGHTLY EARLIER THIS EVENING COMPARED TO LAST EVENING. TRACKING DEWPOINT DEPRESSIONS...IT IS NOW APPARENT THAT PANAMA CITY CIGS AND VSBYS WILL DROP RAPIDLY AFTER SUNSET. FOG HAS ALREADY ARRIVED AT APALACHICOLA. HAVE ADJUSTED PFN TAF ACCORDINGLY. FURTHER INLAND THERE IS STILL A GOOD SPREAD BETWEEN TEMPS AND DEWPOINTS AT THE MOMENT...BUT THIS WON`T LAST. EXPECT CONDITIONS TO DROP TO MVFR AROUND 03Z AND REACHING LIFR BY 06Z OVER MOST INLAND AERODROMES. MODELS CONTINUE TO SHOW HEAVY FOG THROUGH LATE MORNING TOMORROW...THEN SCATTERING OUT TO VFR ON SATURDAY AFTERNOON. && .FIRE WEATHER...NO CONCERNS OVER THE WEEKEND. MUCH COLDER AND EXTREMELY DRY AIR WILL BRING VERY LOW RELATIVE HUMIDITIES ON MON. WILL LIKELY ISSUE A FIRE WEATHER WATCH OVER THE WEEKEND FOR MON AFTERNOON. && .HYDROLOGY...THE CHOCTAWHATCHEE RIVER AT BRUCE IS EXPECTED TO DROP BELOW MODERATE FLOOD STAGE TONIGHT FLOOD STAGE SAT NIGHT. THE APALACHICOLA RIVER AT BLOUNTSTOWN IS DROPPING BELOW FLOOD STAGE THIS EVENING. THE OCHLOCKONEE RIVER AT CONCORD IS ESTIMATED TO DROP BELOW FLOOD STAGE SAT NIGHT. NO OTHER RIVERINE FLOODING IS OCCURRING IN THE FORECAST AREA. && .PREV DISCUSSION... 335 PM EST FRI DEC 19 2008 20Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING AN ACTIVE BUT PROGRESSIVE UPPER LEVEL PATTERN ACROSS MUCH OF THE CONUS THIS MORNING. MAIN FEATURES OF NOTE ASSOCIATED WITH THE NORTHERN STREAM FLOW INCLUDE A DIGGING LONGWAVE TROUGH ACROSS THE PACIFIC NORTHWEST AND A POTENT SHORTWAVE EJECTING NORTHEAST ACROSS THE OHIO VALLEY AND EASTERN GREAT LAKES. THIS SHORTWAVE REMAINS EASILY SEEN ON WV IMAGERY WITH DISTINCT DRYING IN ITS WAKE ACROSS IN/OH. AT THE SURFACE THIS MID-LEVEL ENERGY HAS ASSOCIATED LOW PRESSURE CURRENTLY OVER PENNSYLVANIA WHICH WILL BE SPREADING EASTWARD AND RE-DEVELOPING OFF THE NORTHEAST COAST THIS EVENING. A SIGNIFICANT SNOW/ICING EVENT THAT HAS BEEN ONGOING ACROSS THE GREAT LAKES AND OHIO VALLEY IS NOW SPREADING EASTWARD AHEAD OF THIS LOW INTO THE NORTHEASTERN STATES. SOUTHERN STREAM FLOW CONTINUES FROM THE BAJA REGION EASTWARD ACROSS THE SOUTHERN TIER OF THE U.S. AS IT ARCHES UP AND OVER A LARGE AND DOMINATING MID/UPPER LEVEL RIDGE IN PLACE ACROSS THE GULF OF MEXICO/NORTHWEST CARRIBEAN. CLOSER TO HOME...SURFACE HIGH PRESSURE IN CONTROL OF THE AREA. EXPANSIVE AREA OF FOG AND LOW CLOUDS ACROSS MUCH OF THE AREA THIS MORNING HAS GIVEN WAY TO A MIX OF SUN AND CLOUDS THIS AFTERNOON. ANOTHER VERY WARM DAY FOR DECEMBER ONGOING WITH INLAND TEMPERATURES GENERALLY IN THE MIDDLE 70S WITH LOWER 70S ALONG AT THE COAST. SHORT TERM (TONIGHT THROUGH SUNDAY NIGHT)...SURFACE RIDGE WILL SHIFT SOUTHEAST OVERNIGHT ALLOWING A MORE SOUTHWESTERLY LOW LEVEL FLOW. ABUNDANT MOISTURE COMBINED WITH THE FLOW OFF THE COOLER WATERS SHOULD ONCE AGAIN AID IN FOG FORMATION...ESPECIALLY DURING THE SECOND HALF OF THE NIGHT AND FIRST DAYLIGHT HOURS OF SATURDAY. IMPRESSIVE FOG NUMBERS COMING OUT OF THE SREF ENSEMBLES WITH PROBS FOR WIDESPREAD VISIBILITIES UNDER 1 MILE BETWEEN 70 AND 80 DURING THE LATE NIGHT HOURS (THIS IS HIGH FOR THE SREF). GRIDS TONIGHT WILL SHOW WIDESPREAD FOG WITH AREAS OF DENSE FOG (VIS < 1/4SM) OVER LAND AND THE NEAR SHORE WATERS. WILL CONTINUE THESE GRIDS AS THE DOMINANT WX THROUGH AROUND 10 AM EST. WOULD NOT BE SURPRISED IF DENSE FOG ADVISORIES ARE NEEDED ONCE AGAIN OVER PORTIONS (OR ALL) OF THE AREA LATER TONIGHT INTO SATURDAY MORNING. WILL ALLOW THE EVENING SHIFT TIME TO RE-EVALUATE THIS POTENTIAL BEFORE ISSUING ANY PRODUCT. COLD FRONT TRAILING FROM THE LOW OVER THE NORTHEAST COAST WILL DROP INTO NORTHERN GA/AL/MS OVERNIGHT AND THEN STALL. FORCED ASCENT ALONG THE NOSE OF A LOW LEVEL THETA-E RIDGE ALONG AND TO THE SOUTH OF THIS BOUNDARY MAY BE JUST ENOUGH FOCUS FOR THE DEVELOPMENT OF A FEW SHOWERS ACROSS CENTRAL AL/GA. AT THIS TIME...WOULD EXPECT MOST IF NOT ALL OF THIS ACTIVITY TO REMAIN NORTH OF OUR ZONES AND WILL ONLY ADD A FEW ISOLATED SPRINKLES TO THE GRIDS NORTH OF A LINE FROM AROUND DOTHAN TO ALBANY. LOW TEMPERATURES GENERALLY IN THE MIDDLE AND UPPER 50S INLAND AND THE UPPER 50S TO LOWER 60S AT THE COAST. AFTER THE MORNING FOG/LOW CLOUDS BREAK...LOOKING AT A SIMILAR AFTERNOON TO THE ONE CURRENTLY ONGOING WITH A MIX OF SUN AND CLOUDS AND TEMPS IN THE 70S. HOWEVER...IT SHOULD BE NOTED THAT THIS FOG MAY BE SLOW TO DISSOLVE THROUGH THE MORNING AS WE ARE JUST ABOUT AT AN ANNUAL MINIMUM FOR SOLAR INSOLATION. MID-LEVEL TROUGH CURRENTLY OVER THE PACIFIC NORTHWEST WILL BE AMPLIFYING INTO THE CENTRAL PLAINS DURING SATURDAY. SURFACE LOW PRESSURE MOVING AHEAD OF THIS ENERGY TOWARD THE TN VALLEY WILL ACT TO LIFT THE BOUNDARY BACK TO THE NORTH AS A WARM FRONT THROUGH THE AFTERNOON HOURS AND PULL ANY LIMITED DYNAMICS FOR SHOWERS/SPRINKLES WITH IT. UPPER TROUGH CONTINUES TO SLIDE EAST SATURDAY NIGHT INTO SUNDAY WITH A BIG UPPER LOW TAKING POSITION ACROSS THE GREAT LAKES. SURFACE LOW OVER THE TN VALLEY SAT EVENING TRANSFERS ITS ENERGY TO THE MID-ATLANTIC COAST LATE AT NIGHT. THE TRAILING COLD FRONT FROM THIS LOW WILL BE THE FEATURE THAT FINALLY ENDS OUR STREAK OF UNSEASONABLY WARM TEMPERATURES AS IT SLIDES SOUTHWARD ACROSS THE AREA SUNDAY. FRONT SHOULD BE A FAIRLY QUICK MOVER AS STRONG 1045MB HIGH PRESSURE DIGS INTO THE NORTHERN PLAINS AND PROVIDES A STRONG GRADIENT BEHIND THE BOUNDARY. ALTHOUGH MID/UPPER LEVEL DYNAMICS FOR LIFT ARE LIMITED AT BEST WITH THIS FEATURES...NARROW CORRIDOR OF LOW LEVEL THETA-E ADVECTION SHOULD BE ENOUGH TO PRODUCE A BAND OF SHOWERS ALONG AND AHEAD OF THE FRONT. RAINFALL AMOUNTS SHOULD BE LOW (GENERALLY 0.05-0.15") WITH RAIN DURATION ALSO SHORT. THIS BAND OF SHOWERS SHOULD CROSS THE NW HALF OF THE AREA DURING THE MORNING HOURS AND THEN BECOME MORE BROKEN IN NATURE AS IT EXITS THE EASTERN FLORIDA BIG BEND/SOUTH-CENTRAL GA IN THE AFTERNOON. STRONG COLD AIR ADVECTION BEHIND THE BOUNDARY WILL PREVENT MUCH TEMPERATURE RISE ON SUNDAY WITH TEMPERATURES ACTUALLY HOLDING STEADY OR FALLING SLOWLY DURING THE AFTERNOON. A MUCH DIFFERENT FEEL WILL HAVE ARRIVED BY SUNDAY NIGHT WHEN TEMPERATURES REGION-WIDE WILL BE DROPPING INTO THE 30S WITH CLEARING SKIES AND A STEADY BREEZE OUT OF THE NORTH. MAV NUMBERS SEEM A BIT ON THE COLD SIDE FOR THE AIRMASS...ESPECIALLY SINCE WE WILL BE LOOKING AT ADVECTION...AS OPPOSED TO RADIATIONAL COOLING. CURRENT GRIDS WILL REFLECT TEMPS 2 TO 4 DEGREES ABOVE THESE MAV NUMBERS IN RESPECT TO THE LATEST ECMWF WHICH IS SHOWING A SLIGHTLY WARMER OVERALL AIRMASS. EVEN STILL THIS WILL RESULT IN MANY LOCATIONS FROM VALDOSTA TO TALLAHASSEE AND THEN NORTH AND WEST REACHING THE LOWER 30S FOR A SHORT TIME AROUND SUNRISE MONDAY MORNING. LONG TERM (MONDAY THROUGH FRIDAY)...THE MODELS ARE ALL IN DECENT AGREEMENT THROUGH THE FIRST HALF OF THE LONG-TERM PERIOD...THEN BEGIN TO SLIGHTLY DIVERGE THROUGH THE SECOND HALF. IN THE WAKE OF THE COLD FRONT THAT WAS PREVIOUSLY DISCUSSED ABOVE...CAA AND SUBSIDENCE WILL LEAD TO CLEARING SKIES AND A MUCH DRIER AND COOLER AIRMASS ACROSS THE LOCAL AREA MONDAY INTO TUESDAY. ALTHOUGH THE NORTHERLY WINDS WILL BE UP EARLY MONDAY MORNING...TEMPERATURES WILL DROP DOWN TOWARD AND POSSIBLY BELOW FREEZING EARLY MONDAY AND TUESDAY MORNINGS. HIGHS ARE ONLY FORECAST TO REACH THE UPPER 50S MONDAY AFTERNOON. TUESDAY THROUGH CHRISTMAS EVE...EXPECT CONDITIONS TO MODERATE BACK TO OR ABOVE NORMAL AS THE SURFACE HIGH SHIFTS OFF THE MID-ATLANTIC COAST AND THE NEXT SHORTWAVE AND COLD FRONT TAKE SHAPE WEST OF THE AREA. GUIDANCE IS SHOWING TEMPERATURES REACHING THE UPPER 60S TO LOWER 70S WEDNESDAY AFTERNOON. RAIN CHANCES WILL ALSO BEGIN TO INCREASE THROUGH THIS PERIOD AS THE FRONT CONTINUES TO DEVELOP AND APPROACH FROM THE WEST. WEDNESDAY NIGHT THROUGH CHRISTMAS DAY...THE MODELS SHOW A WEAK COLD FRONT PUSHING ACROSS THE LOCAL AREA. ALTHOUGH THERE ARE SOME DIFFERENCES FROM MODEL TO MODEL...WILL SHOW HIGHER RAIN CHANCES WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING...THEN SHOW A CLEARING TREND FROM WEST TO EAST THROUGH THE DAY THURSDAY. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 56 76 56 63 32 / 0 0 10 50 0 PANAMA CITY 60 73 62 65 35 / 0 0 10 50 0 DOTHAN 59 75 55 59 30 / 10 10 30 60 0 ALBANY 57 76 57 60 30 / 10 10 30 60 0 VALDOSTA 54 76 57 63 32 / 0 0 10 50 0 CROSS CITY 52 76 55 71 34 / 0 0 10 30 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...DENSE FOG ADVISORY ALL ZONES TONIGHT THROUGH SAT MORNING. GA...DENSE FOG ADVISORY ALL ZONES TONIGHT THROUGH SAT MORNING. FL...DENSE FOG ADVISORY ALL ZONES TONIGHT THROUGH SAT MORNING. GM...DENSE FOG ADVISORY FOR THE NEAR SHORE WATERS OUT TO 20NM FROM DESTIN FLORIDA TO THE MOUTH OF THE SUWANNEE RIVER INTO MIDDAY SAT. && $$ PREVIOUS SHORT TERM/MARINE...MROCZKA LONG TERM...GIBBS AVIATION...LANIER REST OF DISCUSSION...WOOL fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 335 PM EST FRI DEC 19 2008 .SYNOPSIS... 20Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING AN ACTIVE BUT PROGRESSIVE UPPER LEVEL PATTERN ACROSS MUCH OF THE CONUS THIS MORNING. MAIN FEATURES OF NOTE ASSOCIATED WITH THE NORTHERN STREAM FLOW INCLUDE A DIGGING LONGWAVE TROUGH ACROSS THE PACIFIC NORTHWEST AND A POTENT SHORTWAVE EJECTING NORTHEAST ACROSS THE OHIO VALLEY AND EASTERN GREAT LAKES. THIS SHORTWAVE REMAINS EASILY SEEN ON WV IMAGERY WITH DISTINCT DRYING IN ITS WAKE ACROSS IN/OH. AT THE SURFACE THIS MID-LEVEL ENERGY HAS ASSOCIATED LOW PRESSURE CURRENTLY OVER PENNSYLVANIA WHICH WILL BE SPREADING EASTWARD AND RE-DEVELOPING OFF THE NORTHEAST COAST THIS EVENING. A SIGNIFICANT SNOW/ICING EVENT THAT HAS BEEN ONGOING ACROSS THE GREAT LAKES AND OHIO VALLEY IS NOW SPREADING EASTWARD AHEAD OF THIS LOW INTO THE NORTHEASTERN STATES. SOUTHERN STREAM FLOW CONTINUES FROM THE BAJA REGION EASTWARD ACROSS THE SOUTHERN TIER OF THE U.S. AS IT ARCHES UP AND OVER A LARGE AND DOMINATING MID/UPPER LEVEL RIDGE IN PLACE ACROSS THE GULF OF MEXICO/NORTHWEST CARRIBEAN. CLOSER TO HOME...SURFACE HIGH PRESSURE IN CONTROL OF THE AREA. EXPANSIVE AREA OF FOG AND LOW CLOUDS ACROSS MUCH OF THE AREA THIS MORNING HAS GIVEN WAY TO A MIX OF SUN AND CLOUDS THIS AFTERNOON. ANOTHER VERY WARM DAY FOR DECEMBER ONGOING WITH INLAND TEMPERATURES GENERALLY IN THE MIDDLE 70S WITH LOWER 70S ALONG AT THE COAST. .SHORT TERM (TONIGHT THROUGH SUNDAY NIGHT)...SURFACE RIDGE WILL SHIFT SOUTHEAST OVERNIGHT ALLOWING A MORE SOUTHWESTERLY LOW LEVEL FLOW. ABUNDANT MOISTURE COMBINED WITH THE FLOW OFF THE COOLER WATERS SHOULD ONCE AGAIN AID IN FOG FORMATION...ESPECIALLY DURING THE SECOND HALF OF THE NIGHT AND FIRST DAYLIGHT HOURS OF SATURDAY. IMPRESSIVE FOG NUMBERS COMING OUT OF THE SREF ENSEMBLES WITH PROBS FOR WIDESPREAD VISIBILITIES UNDER 1 MILE BETWEEN 70 AND 80 DURING THE LATE NIGHT HOURS (THIS IS HIGH FOR THE SREF). GRIDS TONIGHT WILL SHOW WIDESPREAD FOG WITH AREAS OF DENSE FOG (VIS < 1/4SM) OVER LAND AND THE NEAR SHORE WATERS. WILL CONTINUE THESE GRIDS AS THE DOMINANT WX THROUGH AROUND 10 AM EST. WOULD NOT BE SURPRISED IF DENSE FOG ADVISORIES ARE NEEDED ONCE AGAIN OVER PORTIONS (OR ALL) OF THE AREA LATER TONIGHT INTO SATURDAY MORNING. WILL ALLOW THE EVENING SHIFT TIME TO RE-EVALUATE THIS POTENTIAL BEFORE ISSUING ANY PRODUCT. COLD FRONT TRAILING FROM THE LOW OVER THE NORTHEAST COAST WILL DROP INTO NORTHERN GA/AL/MS OVERNIGHT AND THEN STALL. FORCED ASCENT ALONG THE NOSE OF A LOW LEVEL THETA-E RIDGE ALONG AND TO THE SOUTH OF THIS BOUNDARY MAY BE JUST ENOUGH FOCUS FOR THE DEVELOPMENT OF A FEW SHOWERS ACROSS CENTRAL AL/GA. AT THIS TIME...WOULD EXPECT MOST IF NOT ALL OF THIS ACTIVITY TO REMAIN NORTH OF OUR ZONES AND WILL ONLY ADD A FEW ISOLATED SPRINKLES TO THE GRIDS NORTH OF A LINE FROM AROUND DOTHAN TO ALBANY. LOW TEMPERATURES GENERALLY IN THE MIDDLE AND UPPER 50S INLAND AND THE UPPER 50S TO LOWER 60S AT THE COAST. AFTER THE MORNING FOG/LOW CLOUDS BREAK...LOOKING AT A SIMILAR AFTERNOON TO THE ONE CURRENTLY ONGOING WITH A MIX OF SUN AND CLOUDS AND TEMPS IN THE 70S. HOWEVER...IT SHOULD BE NOTED THAT THIS FOG MAY BE SLOW TO DISSOLVE THROUGH THE MORNING AS WE ARE JUST ABOUT AT AN ANNUAL MINIMUM FOR SOLAR INSOLATION. MID-LEVEL TROUGH CURRENTLY OVER THE PACIFIC NORTHWEST WILL BE AMPLIFYING INTO THE CENTRAL PLAINS DURING SATURDAY. SURFACE LOW PRESSURE MOVING AHEAD OF THIS ENERGY TOWARD THE TN VALLEY WILL ACT TO LIFT THE BOUNDARY BACK TO THE NORTH AS A WARM FRONT THROUGH THE AFTERNOON HOURS AND PULL ANY LIMITED DYNAMICS FOR SHOWERS/SPRINKLES WITH IT. UPPER TROUGH CONTINUES TO SLIDE EAST SATURDAY NIGHT INTO SUNDAY WITH A BIG UPPER LOW TAKING POSITION ACROSS THE GREAT LAKES. SURFACE LOW OVER THE TN VALLEY SAT EVENING TRANSFERS ITS ENERGY TO THE MID-ATLANTIC COAST LATE AT NIGHT. THE TRAILING COLD FRONT FROM THIS LOW WILL BE THE FEATURE THAT FINALLY ENDS OUR STREAK OF UNSEASONABLY WARM TEMPERATURES AS IT SLIDES SOUTHWARD ACROSS THE AREA SUNDAY. FRONT SHOULD BE A FAIRLY QUICK MOVER AS STRONG 1045MB HIGH PRESSURE DIGS INTO THE NORTHERN PLAINS AND PROVIDES A STRONG GRADIENT BEHIND THE BOUNDARY. ALTHOUGH MID/UPPER LEVEL DYNAMICS FOR LIFT ARE LIMITED AT BEST WITH THIS FEATURES...NARROW CORRIDOR OF LOW LEVEL THETA-E ADVECTION SHOULD BE ENOUGH TO PRODUCE A BAND OF SHOWERS ALONG AND AHEAD OF THE FRONT. RAINFALL AMOUNTS SHOULD BE LOW (GENERALLY 0.05-0.15") WITH RAIN DURATION ALSO SHORT. THIS BAND OF SHOWERS SHOULD CROSS THE NW HALF OF THE AREA DURING THE MORNING HOURS AND THEN BECOME MORE BROKEN IN NATURE AS IT EXITS THE EASTERN FLORIDA BIG BEND/SOUTH-CENTRAL GA IN THE AFTERNOON. STRONG COLD AIR ADVECTION BEHIND THE BOUNDARY WILL PREVENT MUCH TEMPERATURE RISE ON SUNDAY WITH TEMPERATURES ACTUALLY HOLDING STEADY OR FALLING SLOWLY DURING THE AFTERNOON. A MUCH DIFFERENT FEEL WILL HAVE ARRIVED BY SUNDAY NIGHT WHEN TEMPERATURES REGION-WIDE WILL BE DROPPING INTO THE 30S WITH CLEARING SKIES AND A STEADY BREEZE OUT OF THE NORTH. MAV NUMBERS SEEM A BIT ON THE COLD SIDE FOR THE AIRMASS...ESPECIALLY SINCE WE WILL BE LOOKING AT ADVECTION...AS OPPOSED TO RADIATIONAL COOLING. CURRENT GRIDS WILL REFLECT TEMPS 2 TO 4 DEGREES ABOVE THESE MAV NUMBERS IN RESPECT TO THE LATEST ECMWF WHICH IS SHOWING A SLIGHTLY WARMER OVERALL AIRMASS. EVEN STILL THIS WILL RESULT IN MANY LOCATIONS FROM VALDOSTA TO TALLAHASSEE AND THEN NORTH AND WEST REACHING THE LOWER 30S FOR A SHORT TIME AROUND SUNRISE MONDAY MORNING. && LONG TERM (MONDAY THROUGH FRIDAY)...THE MODELS ARE ALL IN DECENT AGREEMENT THROUGH THE FIRST HALF OF THE LONG-TERM PERIOD...THEN BEGIN TO SLIGHTLY DIVERGE THROUGH THE SECOND HALF. IN THE WAKE OF THE COLD FRONT THAT WAS PREVIOUSLY DISCUSSED ABOVE...CAA AND SUBSIDENCE WILL LEAD TO CLEARING SKIES AND A MUCH DRIER AND COOLER AIRMASS ACROSS THE LOCAL AREA MONDAY INTO TUESDAY. ALTHOUGH THE NORTHERLY WINDS WILL BE UP EARLY MONDAY MORNING...TEMPERATURES WILL DROP DOWN TOWARD AND POSSIBLY BELOW FREEZING EARLY MONDAY AND TUESDAY MORNINGS. HIGHS ARE ONLY FORECAST TO REACH THE UPPER 50S MONDAY AFTERNOON. TUESDAY THROUGH CHRISTMAS EVE...EXPECT CONDITIONS TO MODERATE BACK TO OR ABOVE NORMAL AS THE SURFACE HIGH SHIFTS OFF THE MID-ATLANTIC COAST AND THE NEXT SHORTWAVE AND COLD FRONT TAKE SHAPE WEST OF THE AREA. GUIDANCE IS SHOWING TEMPERATURES REACHING THE UPPER 60S TO LOWER 70S WEDNESDAY AFTERNOON. RAIN CHANCES WILL ALSO BEGIN TO INCREASE THROUGH THIS PERIOD AS THE FRONT CONTINUES TO DEVELOP AND APPROACH FROM THE WEST. WEDNESDAY NIGHT THROUGH CHRISTMAS DAY...THE MODELS SHOW A WEAK COLD FRONT PUSHING ACROSS THE LOCAL AREA. ALTHOUGH THERE ARE SOME DIFFERENCES FROM MODEL TO MODEL...WILL SHOW HIGHER RAIN CHANCES WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING...THEN SHOW A CLEARING TREND FROM WEST TO EAST THROUGH THE DAY THURSDAY. && .AVIATION... CIGS AND VSBYS SCATTERED OUT TO VFR AROUND NOON TODAY WITH CIGS RANGING AROUND 5KFT THIS AFTERNOON. LIGHT SW WINDS WILL GO MOSTLY VERY LIGHT TO CALM OVERNIGHT OVER INLAND AREAS. HOWEVER WIDESPREAD VERY HEAVY ADVECTION FOG TRANSPORTED IN THE BOUNDARY LAYER FROM THE GOMEX IS EMPHATICALLY PREDICTED BY THE MODELS FOR TONIGHT. EXPECT IFR CONDITIONS STARTING BEFORE MIDNIGHT TONIGHT DROPPING RAPIDLY TO LIFR AND VLIFR AROUND MIDNIGHT MOST AERODROMES. THE HEAVY FOG WILL LAST TO 11AM TOMORROW MORNING. CONDITIONS SHOULD RAISE TO MVFR BY NOON AND IMPROVE TO VFR BY EARLY AFTERNOON. && .MARINE... DENSE FOG ADVISORY NOW IN EFFECT FOR THE NEAR SHORE WATERS DURING THE SECOND HALF OF TONIGHT INTO SATURDAY MORNING. BEST CHANCES FOR THE MOST WIDESPREAD FOG AND LOWEST VISIBILITIES WILL BE ACROSS THE WATERS ADJACENT TO GULF COUNTY AND EASTWARD. HIGH PRESSURE IN CONTROL OF THE MARINE AREA WILL CONTINUE TO PROVIDE A GENERALLY LIGHT SOUTH FLOW WITH LOW SEAS INTO TONIGHT. THE RIDGE OF HIGH PRESSURE WILL SLIDE A BIT FURTHER SOUTH AND EAST INTO SATURDAY ALLOWING WINDS TO COME AROUND TO THE SOUTHWEST WITH TIME. MAIN CONCERN WILL REMAIN THE EXPECTED RE-DEVELOPMENT OF MAINLY NEAR SHORE FOG. THIS FOG IS LIKELY TO BECOME LOCALLY DENSE...ESPECIALLY ALONG THE COASTS OF GULF... FRANKLIN...WAKULLA AND TAYLOR COUNTIES...AND MAY LINGER THROUGH MUCH OF SATURDAY MORNING. WINDS AND SEAS SHOULD NOT SHOW A SIGNIFICANT INCREASE TOWARD CAUTIONARY LEVELS UNTIL THE APPROACH AND PASSAGE OF A COLD FRONT DURING SATURDAY NIGHT AND SUNDAY. A PERIOD OF ADVISORY LEVEL WINDS FROM THE NORTHWEST AND NORTH ARE BECOMING MORE LIKELY BEHIND THIS FRONT FOR SUNDAY AFTERNOON INTO MONDAY. && .FIRE WEATHER... WARM MOIST CONDITIONS WILL CONTINUE INTO SUNDAY WITH RELATIVE HUMIDITIES WELL ABOVE THRESHOLDS AND LOW DISPERSION INDICES BOTH IN THE MORNING AND AFTERNOON THRU SUNDAY MORNING. A COLD FRONT WILL MOVE RAPIDLY THROUGH THE AREA WITH A FEW LIGHT SHOWERS ON SUNDAY. MUCH COLDER AND EXTREMELY DRY AIR WILL BRING VERY LOW RELATIVE HUMIDITIES ON MONDAY. WILL LIKELY ISSUE A RED FLAG WATCH TOMORROW FOR MONDAY AFTERNOON. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 56 76 56 63 32 / 0 0 10 50 0 PANAMA CITY 60 73 62 65 35 / 0 0 10 50 0 DOTHAN 59 75 55 59 30 / 10 10 30 60 0 ALBANY 57 76 57 60 30 / 10 10 30 60 0 VALDOSTA 54 76 57 63 32 / 0 0 10 50 0 CROSS CITY 52 76 55 71 34 / 0 0 10 30 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...DENSE FOG ADVISORY FOR THE NEAR WATERS OUT TO 20NM FROM DESTIN FLORIDA TO THE MOUTH OF THE SUWANNEE RIVER AFTER MIDNIGHT TONIGHT THROUGH SATURDAY MORNING. && $$ SYNOPSIS/SHORT TERM/MARINE...MROCZKA LONG TERM...GIBBS AVIATION/FIRE WEATHER...LANIER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 945 AM EST FRI DEC 19 2008 .SYNOPSIS... 14Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING AN ACTIVE BUT PROGRESSIVE UPPER LEVEL PATTERN ACROSS MUCH OF THE CONUS THIS MORNING. MAIN FEATURES OF NOTE ASSOCIATED WITH THE NORTHERN STREAM FLOW INCLUDE A DIGGING LONGWAVE TROUGH ACROSS THE PACIFIC NORTHWEST AND A POTENT SHORTWAVE EJECTING NORTHEAST OUT OF THE MIDDLE MS VALLEY AND ACROSS THE GREAT LAKES. THIS SHORTWAVE IS EASILY SEEN ON WV IMAGERY WITH DISTINCT DRYING IN ITS WAKE ACROSS MO/IL/IN (EVEN A FEW LIGHTNING STRIKES ACROSS NORTHERN INDIANA). AT THE SURFACE THIS MID-LEVEL ENERGY HAS ASSOCIATED LOW PRESSURE CURRENTLY OVER OHIO WHICH WILL BE SPREADING EASTWARD TO THE NORTHEAST COAST THIS EVENING. A SIGNIFICANT SNOW/ICING EVENT CURRENTLY ONGOING ACROSS THE GREAT LAKES AND OHIO VALLEY WILL BE SPREADING EASTWARD AHEAD OF THIS LOW INTO THE NORTHEASTERN STATES THROUGH THE DAY. SOUTHERN STREAM FLOW CONTINUES FROM THE BAJA REGION EASTWARD ACROSS THE SOUTHERN TIER OF THE U.S. AS IT ARCHES UP AND OVER A LARGE AND DOMINATING MID/UPPER LEVEL RIDGE IN PLACE ACROSS THE GULF OF MEXICO/NORTHWEST CARRIBEAN. CLOSER TO HOME...SURFACE HIGH PRESSURE IN CONTROL OF THE AREA. ABUNDANT LOW LEVEL MOISTURE HAS RESULTED IN A EXPANSIVE AREA OF FOG AND LOW CLOUDS ACROSS MUCH OF THE AREA. ONLY ZONES THAT HAVE ESCAPED THIS FOG THOSE CLOSER TO THE I-75 CORRIDOR WHERE MOSTLY SUNNY SKIES ARE BEING EXPERIENCED THIS MORNING. FOG AND LOW STRATUS WILL SLOWLY BREAK UP THROUGH THE REMAINDER OF THE MORNING WITH A MIX OF SUN AND CLOUDS REGION-WIDE FOR THE AFTERNOON. MAY SEE THE FOG LINGER A BIT LONGER ALONG THE COASTLINE OF GULF...FRANKLIN...AND WAKULLA COUNTIES...BUT EVEN THESE LOCATIONS SHOULD SEE AT LEAST BREAKS OF SUN. ANOTHER UNSEASONABLY WARM DAY FOR MID DECEMBER WITH HIGH TEMPS INTO THE MIDDLE AND UPPER 70S. DUE TO THE SOUTHERLY FLOW...LOCATIONS ALONG THE IMMEDIATE COAST SHOULD END UP A FEW DEGREES COOLER UNDER THE INFLUENCE OF THE RELATIVELY COOLER SHELF WATERS. SURFACE RIDGE WILL SHIFT TO THE SOUTHEAST TONIGHT ALLOWING A MORE SOUTHWESTERLY LOW LEVEL FLOW. ABUNDANT MOISTURE COMBINED WITH THE FLOW OFF THE COOLER WATERS SHOULD ONCE AGAIN RESULT IN AREAS TO WIDESPREAD FOG FORMATION...ESPECIALLY DURING THE SECOND HALF OF THE NIGHT AND FIRST FEW DAYLIGHT HOURS OF SATURDAY. IMPRESSIVE FOG NUMBERS COMING OUT OF THE SREF ENSEMBLES WITH PROBS FOR WIDESPREAD VISIBILITIES UNDER 1 MILE BETWEEN 70 AND 80 DURING THE LATE NIGHT HOURS (THIS IS HIGH FOR THE SREF). GRIDS TONIGHT WILL SHOW WIDESPREAD FOG WITH AREAS OF DENSE FOG (VIS < 1/4SM) AND WILL CONTINUE THIS AS THE DOMINANT WX THROUGH AROUND 10 AM EST. WOULD NOT BE SURPRISED IF DENSE FOG ADVISORIES ARE NEEDED ONCE AGAIN OVER PORTIONS (OR ALL) OF THE AREA INTO SATURDAY MORNING. AFTER THE MORNING FOG/LOW CLOUDS BREAK UP SHOULD BE LOOKING AT ANOTHER AFTERNOON WITH A MIX OF SUN AND CLOUDS AND TEMPS IN THE 70S. && .AVIATION... HEAVY FOG ACROSS THE ENTIRE AREA INCLUDING PANHANDLE MARINE AREAS LAST NIGHT DUE TO COLD SHELF WATERS. FOG WILL PERSIST ALONG PANHANDLE COASTAL AREAS BUT ALL AERODROMES SHOULD BREAK OUT TO VFR WITH 3KFT SCT CLOUDS BY NOON AT THE LATEST. SOUTHWESTERLY WINDS WILL KEEP PUMPING MOIST AIR ACROSS THE REGION. VERY HEAVY WIDESPREAD DENSE FOG TO VLIFR LEVELS TO REAPPEAR EARLY TONIGHT AT ALL AERODROMES LASTING THROUGH MID MORNING ON SATURDAY. COLD FRONT ON SUNDAY WILL WITH LIGHT SHOWERS WILL BLOW THE FOG OUT OF THE AREA ON SUNDAY. && .MARINE... HIGH PRESSURE IN CONTROL OF THE MARINE AREA WILL CONTINUE TO PROVIDE A GENERALLY LIGHT SOUTH TO SOUTHEAST FLOW WITH LOW SEAS INTO THE EVENING. MAIN CONCERN WILL REMAIN AREAS OF DENSE FOG ACROSS THE NEAR SHORE WATERS...ESPECIALLY ALONG THE COASTS OF GULF...FRANKLIN AND WAKULLA COUNTIES. THIS RIDGE OF HIGH PRESSURE WILL SLIDE A BIT FURTHER SOUTH AND EAST TONIGHT INTO SATURDAY ALLOWING WINDS TO COME AROUND TO THE SOUTHWEST WITH TIME. WINDS AND SEAS SHOULD NOT SHOW A SIGNIFICANT INCREASE TOWARD CAUTIONARY LEVELS UNTIL THE APPROACH AND PASSAGE OF A COLD FRONT DURING THE DAY SUNDAY. A PERIOD OF ADVISORY LEVEL WINDS FROM THE NORTHWEST AND NORTH ARE BECOMING MORE LIKELY BEHIND THIS FRONT FOR SUNDAY EVENING INTO MONDAY. && .HYDROLOGY...FORECAST FOR THE CHOCTAWHATCHEE RIVE AT BRUCE SHOWS THAT RIVER HAS CRESTED BUT IS NOW EXPECTED TO REMAIN ABOVE MODERATE FLOOD STAGE UNTIL FRI NIGHT AND NOT DROP BELOW FLOOD STAGE UNTIL SUN MORNING. UPSTREAM AT CARYVILLE, THE RIVER CONTINUES TO DROP BELOW FLOOD STAGE. THE CHIPOLA RIVER IS NOW BELOW FLOOD STAGE THROUGHOUT ITS COURSE. THE APALACHICOLA RIVER AT BLOUNTSTOWN IS FORECAST TO DROP BELOW FLOOD STAGE AROUND MIDDAY SUN. THE RIVER HAS CRESTED DOWNSTREAM AT SUMATRA. THE OCHLOCKONEE RIVER AT CONCORD IS GRADUALLY FALLING. DOWNSTREAM AT HAVANA, THE RIVER CRESTED ON FRIDAY AT FLOOD STAGE. NO OTHER RIVERINE FLOODING IS OCCURRING IN THE FORECAST AREA. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 77 55 75 55/ 0 0 0 0 PANAMA CITY 73 60 74 59/ 0 0 0 0 DOTHAN 76 57 76 55/ 0 0 0 0 ALBANY 77 57 78 56/ 0 0 0 0 VALDOSTA 78 55 78 56/ 0 0 0 0 CROSS CITY 78 52 78 54/ 0 0 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...DENSE FOG ADVISORY UNTIL 21Z FRI FOR GMZ750. && $$ SYNOPSIS/UPDATE/MARINE...MROCZKA AVIATION...LANIER HYDROLOGY...BLOCK fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1129 AM CST SAT DEC 20 2008 .DISCUSSION... ISSUED 1039 AM CST SAT DEC 20 2008 SHORT-WAVE TRACKING ACROSS THE NORTHERN PLAINS IS SPREADING LIGHT TO MODERATE SNOW EASTWARD ACROSS IOWA THIS MORNING...WITH LATEST RADAR MOSAIC NOW SHOWING THE SNOW BEGINNING TO ARRIVE ACROSS EASTERN IOWA. 12Z RUC/NAM-WRF SEEM TO BE HANDLING SYSTEM WELL...AS IT QUICKLY PUSHES INTO THE GREAT LAKES LATER THIS EVENING. WITH SLIGHTLY FASTER EVOLUTION...HAVE BUMPED POPS INTO THE HIGH CHANCE CATEGORY ACROSS THE FAR NORTH AND HAVE INCLUDED SLIGHT CHANCE POPS AS FAR SOUTHEAST AS THE I-72 CORRIDOR FOR LATE THIS AFTERNOON. BEST SHOT AT SEEING LIGHT SNOW STILL APPEARS TO BE THIS EVENING...BEFORE SYSTEM RAPIDLY DEPARTS THE REGION. ACCUMULATIONS WILL BE ON THE LIGHT SIDE...WITH WELL UNDER ONE INCH EXPECTED ALONG AND NORTH OF I-74. && .AVIATION... ISSUED 1129 AM CST SAT DEC 20 2008 LOW CEILINGS OF AROUND 1000FT WILL PERSIST ACROSS CENTRAL ILLINOIS THIS AFTERNOON IN ADVANCE OF AN APPROACHING STORM SYSTEM. WINDS WILL BE OUT OF THE E/SE AT AROUND 10KT...DIMINISHING TO LESS THAN 10KT AS A TROUGH AXIS SWINGS TOWARD THE AREA LATER THIS AFTERNOON. LIGHT TO OCCASIONALLY MODERATE SNOW WITH THIS SYSTEM WILL SKIRT CENTRAL ILLINOIS TO THE NORTH...MAINLY AFFECTING THE NORTHERNMOST TERMINALS LATE THIS AFTERNOON INTO THE EVENING. HAVE INCLUDED CEILINGS BELOW 1000FT AND VISBYS DOWN TO 3 TO 4SM AT BOTH KPIA AND KBMI BETWEEN 22Z AND 05Z. FURTHER SOUTH...WILL BRING IN A PERIOD OF LIGHTER SNOW WITH HIGHER CEILINGS AND VISBYS. ALL PRECIP WILL QUICKLY CLEAR THE AREA TOWARD MIDNIGHT...AS GUSTY W/NW WINDS DEVELOP IN THE WAKE OF THE DEPARTING SYSTEM. WINDS WILL GUST AS HIGH AS 30KT OVERNIGHT...THEN UP TO 35KT DURING THE DAY SUNDAY. CONDITIONS WILL REMAIN OVERCAST THROUGH THE ENTIRE 18Z TAF PERIOD...ALTHOUGH BUFKIT SOUNDING DATA SUGGESTS CEILINGS RISING TO AROUND 1500FT AFTER 14Z SUN. BARNES && .PREV DISCUSSION... ISSUED 220 AM CST SAT DEC 20 2008 LATEST SURFACE MAP SHOWED HIGH PRESSURE RIDGE EXTENDING SOUTHWEST INTO THE CWA. HOWEVER...EXTENSIVE LOW CLOUDS WERE HELPING TO KEEP TEMPERATURES FROM DROPPING OFF QUICKLY. UPSTAIRS...140 KNOT JET FLOWING OVERHEAD AT THE 300 MB LEVEL. BITTERLY COLD AIRMASS FOUND ACROSS MONTANA AND WESTERN NORTH DAKOTA...BEHIND INVERTED SURFACE TROUGH AND COLD FRONT ACROSS THE EASTERN DAKOTAS. MAIN FORECAST ISSUE IN THE SHORT TERM IS HOW THIS COLD AIR MASS WILL AFFECT OUR AREA SUNDAY AND SUNDAY NIGHT...RESULTING IN WIND CHILLS NEAR OR ABOVE ADVISORY LEVELS. IN THE LONGER TERM...PRECIPITATION CHANCES TUESDAY INTO CHRISTMAS EVE DAY ARE THE PRIMARY FOCUS. SHORT TERM...TODAY THROUGH MONDAY... HIGH PRESSURE TO GIVE WAY TO A STRONG COLD FRONT...MOVING IN FROM THE PLAINS LATER TODAY. CURRENTLY AM EXPECTING THE BULK OF THE ASSOCIATED SNOWFALL TO REMAIN JUST TO OUR NORTH...BUT HAVE 30-40 PERCENT POPS GOING ACROSS ROUGHLY THE NORTHERN THIRD OR SO OF THE CWA FOR THE AFTERNOON AND EVENING. NOT EXPECTING MORE THAN A DUSTING IF THAT. MODELS IN AGREEMENT ABOUT PUSHING THE FRONT ITSELF ACROSS THE CWA BY LATE EVENING...AND INTENSIFYING THE PARENT LOW PRESSURE AS IT PUSHES EAST ACROSS THE GREAT LAKES. WITH STRONG CANADIAN HIGH PRESSURE BEHIND IT...THE PRESSURE CONTRAST WILL RESULT IN BLUSTERY WEST WINDS SUNDAY AND SUNDAY EVENING. THERE IS LESS AGREEMENT WITH HOW LOW TEMPERATURES ARE EXPECTED TO GET...WITH GFS MOS KEEPING ITS WARMER BIAS GOING. UNDERCUT THE COLDER NAM MOS ACROSS THE NORTH BY A COUPLE DEGREES WHERE EXISTING SNOW/ICE COVER IS MORE SUBSTANTIAL...AND USED MORE OF A BLEND BETWEEN NAM/GFS MOS FURTHER SOUTH. THE RESULTING NUMBERS GIVE WIND CHILL READINGS COLDER THAN 15 BELOW ACROSS THE NORTHERN CWA EVEN DURING THE DAY. ELECTED TO RAISE A WIND CHILL ADVISORY FOR SUNDAY AND SUNDAY NIGHT GENERALLY NORTH OF HIGHWAY 136. AREAS FURTHER SOUTH TOWARD I-72 WILL BE ON THE FENCE WITH THE CRITERIA OF 15 BELOW...AND WILL LEAVE THEM OUT AT THIS TIME. WINDS SHOULD BEGIN TO SUBSIDE LATER SUNDAY NIGHT AND INTO MONDAY...AS CENTER OF HIGH PRESSURE MOVES INTO SOUTHERN ILLINOIS. LONG TERM...TUESDAY THROUGH FRIDAY... NEXT FOCUS IS ON STORM SYSTEM ASSOCIATED WITH DEVELOPING UPPER TROUGH ACROSS THE WESTERN U.S. EARLY NEXT WEEK. MAIN FRONTAL BOUNDARY PROGGED TO COME THROUGH ILLINOIS ON WEDNESDAY...BUT PRECIPITATION IS EXPECTED TO BEGIN SPREADING INTO THE AREA ON TUESDAY. THERMAL PROFILES REMAIN TROUBLING REGARDING THE POSSIBILITY OF ANOTHER ROUND OF FREEZING RAIN/SNOW. AREAS NORTHWEST OF I-55 CURRENTLY LOOK TO BE MORE LIKELY TO SEE SNOW...WITH THE MIXTURE TO THE SOUTHEAST. HOWEVER...THIS IS STILL QUITE AWAYS OUT...AND CAN EASILY CHANGE BY THE TIME TUESDAY ROLLS AROUND. PRECIPITATION EXPECTED TO LINGER INTO CHRISTMAS EVE BEFORE DIMINISHING BY EVENING...WITH HIGH PRESSURE PROVIDING QUIET WEATHER FOR THE HOLIDAY. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... WIND CHILL ADVISORY FROM 6 AM SUNDAY TO 6 AM CST MONDAY FOR ILZ027>031-036>038. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 501 PM MST SAT DEC 20 2008 .DISCUSSION...THE 20Z SURFACE ANALYSIS HAS HIGH PRESSURE OVER THE CENTRAL AND NORTHERN PLAINS. VISIBLE SATELLITE SHOWING SOME CLOUDS OVER THE FORECAST AREA WITH MORE UPSTREAM. WATER VAPOR IMAGERY INDICATES A DISTURBANCE MOVING SOUTHEAST TOWARD NORTHWEST KANSAS. UPPER FLOW WILL BE NORTHWEST TONIGHT AND SUNDAY AS A RIDGE BUILDS INTO THE ROCKIES. THE RIDGE MOVES EAST OF THE ROCKIES AND ACROSS THE NORTHERN PLAINS WITH ZONAL FLOW ACROSS THE CENTRAL PLAINS. SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE CENTRAL PLAINS TONIGHT AND SUNDAY. THE HIGH WILL DRIFT EAST ON MONDAY FOLLOWED BY A TROUGH OVER EASTERN COLORADO. THE TROUGH WILL MOVE EAST TUESDAY NIGHT. THE MAIN FORECAST ISSUES ARE TEMPERATURES AND WIND CHILL POTENTIAL AS WELL AS POPS FOR TONIGHT AND TUESDAY. ADDED A SLIGHT CHANCE OF LIGHT SNOW TONIGHT ACROSS THE NORTHERN ZONES DUE TO A SHORTWAVE CURRENTLY OVER SOUTHWEST COLORADO WHICH WILL MOVE THROUGH DURING THE LATE EVENING AND OVERNIGHT. THE BEST MOISTURE IS OVER THE NORTH BUT CANNOT RULE OUT AT LEAST FLURRIES SOUTH OF THAT AREA. FORCING AND MOISTURE APPEARS TO DECREASE AFTER 06Z SO WILL LEAVE FLURRIES OUT OF THE EASTERN ZONES. FOR THE SNOW EVENT ON TUESDAY...DECIDED TO ADD A SMALL AREA OF SLIGHT CHANCE POPS OVER THE NORTHWEST ZONES. TIMING OF THE FRONT AND MOISTURE SHOULD PROVIDE AT LEAST A SLIGHT CHANCE THERE AFTER 06Z TUESDAY. OTHERWISE TUESDAY EVENT STILL LOOKS ON TRACK BUT LEFT POPS AT SLIGHT CHANCE. BY TUESDAY NIGHT THE SHORTWAVE LIFTS OUT LEAVING SUBSIDENCE OVER THE FORECAST AREA. PLAN TO HAVE A SMALL AREA OF FLURRIES OVER THE FAR SOUTH ZONES OTHERWISE WILL REMOVE POPS. ALL OTHER PERIODS...SUNDAY THROUGH MONDAY EVENING WILL BE DRY WITH NIL POPS DUE TO SUBSIDENCE. WIND CHILL VALUES ARE IN QUESTION DUE TO WIND SPEED BEHIND THE EXITING SHORTWAVE SUNDAY MORNING. AT THE WORST WIND SPEEDS WILL BE ABOUT 12 MPH OR JUST ABOVE THE CRITERIA FOR A FEW HOURS JUST BEFORE AND AFTER SUNRISE. HOWEVER WIND SPEEDS MAY BE LOWER IF THE GFS WINDS ARE RIGHT. LOWER WINDS ARE ALSO SUPPORTED BY THE RUC. THERE MAY BE A FEW HOURS AROUND 12Z WHERE WIND CHILLS WILL BE BORDERLINE OR JUST ABOVE CRITERIA. THE POTENTIAL GOES AWAY QUICKLY AFTER 12Z. TEMPERATURES TONIGHT SHOULD BE HELD UP SOME BY INCREASING CLOUDS AS THE NEXT SHORTWAVE APPROACHES. MINS ARE FORECAST NEAR OR JUST BELOW ZERO. BY SUNDAY NIGHT RETURN FLOW WILL HELP BRING SOME WARMER AIR BACK TO THE FORECAST AREA. LOWS SHOULD STAY ABOVE ZERO WITH SINGLE DIGIT READINGS. MINS WILL CONTINUE TO WARM MONDAY NIGHT WITH INCREASING CLOUDS. READINGS SHOULD BE IN THE TEENS. TUESDAY NIGHT LOWS WILL FALL BACK INTO THE UPPER SINGLE DIGITS WITH SOME POSSIBLE SNOW ON THE GROUND. DAYTIME HIGH TEMPERATURES SHOULD WARM INTO THE TEENS SUNDAY WARMING TO THE 20S MONDAY/TUESDAY. IN THE EXTENDED...(WEDNESDAY THROUGH SATURDAY)...WESTERLY FLOW WILL DOMINATE THIS FORECAST. HOWEVER THERE ARE SOME MAJOR DIFFERENCES BETWEEN THE GFS AND THE ECMWF BY FRIDAY NIGHT/SATURDAY. THE GFS BRINGS AN UPPER LOW INTO A FAVORABLE POSITION FOR A WINTER STORM WHILE THE EUROPEAN TAKES AN OPEN TROUGH ACROSS THE NORTHERN PLAINS WITH ZONAL FLOW ACROSS THE CENTRAL PLAINS. FOR NOW WILL KEEP THE FORECAST DRY AND WAIT FOR FURTHER MODEL RUNS TO GET RESOLUTION ON THIS. MAX TEMPERATURES WILL WARM BACK INTO ABOVE NORMAL 40S WITH ZONAL FLOW DOMINATING. MINS WILL RISE BACK TO A FEW DEGREES ABOVE NORMAL WITH READINGS IN THE UPPER TEENS/LOW 20S. FS && .AVIATION... 501 PM MST SAT DEC 20 2008 FOR THE 00Z TAFS...VFR WILL PREVAIL THROUGH THE PERIOD WITH LIGHT AND VARIABLE WINDS THROUGH THE NIGHT. SOME CONCERN FOR A FEW FLURRIES AT KGLD AS MID LEVEL FRONTAL ZONE TRANSLATES SLOWLY SOUTHEAST OVER THE AREA THROUGH THE NIGHT. CURRENT THINKING IS THAT OUTSIDE A BRIEF PERIOD OF MVFR WITH -SN/LOW CIGS, VFR WILL PREVAIL. A SECONDARY CONCERN IS PATCHY FOG DEVELOPING IN THE KMCK AREA AS ARCTIC HIGH PRESSURE BUILDS INTO THE REGION. DEWPOINT TEMPERATURES UPSTREAM REMAIN LARGE THIS EVENING SO CONFIDENCE IN CEILING AND/OR VISIBILITY CROSSING FLIGHT RULE CATEGORY THRESHOLDS REMAINS LOW. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ ks AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 700 PM EST SAT DEC 20 2008 UPDATED AVIATION SECTION FOR 00Z TAFS .SYNOPSIS... WATER VAPOR IMAGE AND RUC SHOWING A CLOSED LOW OVER NORTHWEST NORTH DAKOTA...PUSHING A RIDGE OVER WESTERN ONTARIO AND THE UPPER GREAT LAKES REGIONS. WEAK SHORTWAVES ARE BEING EJECTED OUT AHEAD OF THIS LOW AND ARE OVER MANITOBA AND MINNESOTA. SURFACE ANALYSIS DEPICTS AN INVERTED TROUGH STRETCHING FROM WESTERN IOWA NORTH INTO SOUTHEAST MANITOBA. THIS TROUGH IS SEPARATING A RIDGE OVER EASTERN ONTARIO FROM A HIGH OVER SOUTHWEST CANADA. ANOTHER SIGNIFICANT LOW IS OVER THE MIDDLE MISSISSIPPI RIVER VALLEY. A STATIONARY FRONT STRETCHES EAST FROM THIS LOW ACROSS THE SOUTHEASTERN STATES. && .SHORT TERM...TONIGHT AND SUNDAY. STRONG LIFT PER 700-500MB Q-VECTOR DIVERGENCE AND DEEP MOISTURE THROUGH 20KFT THIS EVENING WILL ALLOW FOR 3 TO 4 INCHES OF SYNOPTIC SNOW TO FALL TONIGHT AS INVERTED TROUGH SHIFTS INTO FORECAST AREA AFTER 00Z. MAIN SNOW WON`T ARRIVE UNTIL AFT 00Z. A SURFACE LOW EJECTING OUT OF TEXAS THIS AFTERNOON WILL MERGE WITH THE TROUGH OVER THE LOWER GREAT LAKES SUNDAY MORNING. AS THIS HAPPENS THE RESULTING NORTHEASTERLY FLOW WILL ALLOW FOR HEAVY LES TO DEVELOP OVER NORTH CENTRAL AND WESTERN UPPER MICHIGAN. WINTER STORM WARNINGS REMAIN IN EFFECT FOR GOGEBIC/ONTONAGON/MARQUETTE/ALGER. ADVISORIES WILL KEEP ELSEWHERE AS NOT ENOUGH CONFIDENCE IN REACHING WARNING CRITERIA. TONIGHT THROUGH SUNDAY UP TO 8 INCHES OR MORE OF LES MAY FALL ACROSS THE HIGHER TERRAIN OF MARQUETTE COUNTY...AREAS OF KEWEENAW COUNTY AND INTO WESTERN GOGEBIC/ONTONAGON COUNTIES. THIS IS FURTHER SUPPORTED BY THE LOCAL WRF MODEL. CONCERN ABOUT POSSIBLE LAKE ENHANCED SNOW SHOWERS OVER MENOMINEE COUNTY...FOR POSSIBLE NEED FOR WARNING. HOWEVER...WRF/NAM12 SHOWING WINDS BACKING NORTH SHORTLY AFTER SUNRISE OVER SOUTHERN COUNTIES...DRIER AIR ADVECTING IN...AND LACK OF TERRAIN SUPPORT OF LES. THUS WILL STAY WITH THE CURRENT ADVISORIES FOR THAT AREA TOO. AFTER COORDINATED WITH GRB DECIDED TO STAY WITH THE ADVISORY FOR NOW. && .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY. SUN NIGHT...EXPECT TRANSITION FROM LAKE ENHANCED TO LAKE EFFECT SNOW WITH CONTINUED VERY FAVORABLE SNOW GROWTH PARAMETERS WITH GOOD UPWARD MOTION IN THE DGZ THROUGH 06Z/MON. EVEN THOUGH SNOW/WATER RATIOS SHOULD BE AOA 30/1 DURING THE EVENING...WITH CONTINUED WINDY CONDITIONS...FRACTURING AND DRIFTING SHOULD REDUCE ACTUAL/OBSERVED SNOW TOTALS. NEVERTHELESS...ADDITIONAL AMOUNTS IN THE 2 TO 6 INCH RANGE ARE EXPECTED FOR N WIND FAVORED SNOWBELTS...WITH THE GREATEST AMOUNTS IN THE HIGHER TERRAIN WHERE STRONG UPSLOPE LIFT WILL OCCUR. OVERNIGHT...WITH BACKING WINDS...LOWERING INVERSION HEIGHTS/ EXIT OF DEEPER MOISTURE...SNOWFALL RATES WILL TAPER OFF AND LES SHOULD SHIFT TOWARD NW FLOW FAVORED AREAS. BLOWING SNOW SHOULD ALSO SUBSIDE OVERNIGHT AS THE GRADIENT WEAKENS IN THE WAKE OF THE DEPARTING LOW. AS WINDS BACK TO WRLY BY MIDDAY MON...LES WILL SHIFT INTO THE KEWEENAW AND FAR NE UPPER MI WHILE RELATIVELY TRANQUIL WEATHER PREVAILS ACROSS THE REST OF THE CWA. BEFORE CLOUDS THICKEN MON NIGHT IN ADVANCE OF THE NEXT SHRTWV...TEMPS MAY PLUMMET CLOSER TO LOWER NAM GUIDANCE VALUES NEAR -10F WELL INLAND. TUE...MDLS WERE IN GOOD AGREEMENT WITH THE NEXT MID LEVEL AND SFC TROUGH THAT WILL MOVE THROUGH THE REGION BRINGING ANOTHER ROUND OF SNOW. MDLS TEMP/UVV/RH PROFILE SUGGEST SNOW/WATER MAY BE RELATIVELY LOW WITH BEST LIFT ABOVE THE DGZ. SO WITH QPF VALUES IN THE 0.10 TO 0.20 RANGE AND SNOW/WATER RATIOS NEAR 15/1 ACCUMULATIONS MAINLY IN THE 1 TO 3 INCH RANGE WOULD BE EXPECTED. WED...SIGNIFICANT UNCERTAINTY REMAINS WITH THE POTENTIAL FOR ANOTHER STRONGER SHRTWV AND SFC LOW DEVELOPMENT. THE 12Z ECMWF AND UKMET FAVORED POTENTIAL FOR HEAVIER SNOW WITH THIS FEATURE WHILE THE GFS AND CMC DID NOT. IF THE EURO MODELS VERIFY...ANOTHER HEAVY SNOW EVENT WOULD BE EXPECTED WITH FAVORABLE SCENARIO FOR LAKE ENHANCED SNOW IN N CNTRL UPPER MI. THU-SAT...THE FCST GENERALLY FOLLOWED THE HPC PREFERRED ECMWF/CMC MDLS SCENARIO WHICH ALSO HAD DECENT SUPPORT FROM THE 12Z GFS ENSEMBLES. THE 06Z/12Z WAS AN OUTLIER IN BRINGING A WEAKER NRN STREAM SYSTEM THROUGH THE NRN TIER AND DELAYING THE EJECTION OF A STRONGER SHRTWV FROM THE SW CONUS. SO...WITH A SW FLOW PATTERN AND STRONGER SE CONUS RIDGE...A SHRTWV AND SFC LOW TRACK THROUGH OR WEST OF CNTRL UPPER MI COULD BRING POTENTIAL FOR MIXED PCPN (SN/FZRA/PL/RA) AND A BRIEF WARMUP AOA FREEZING BY LATE FRI. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... SNOW IS SPREADING INTO THE SOUTHERN PORTION OF UPPER MICHIGAN AS UPPER DISTURBANCE AND SURFACE TROUGH PUSH INTO THE AREA. EXPECT LGT SNOW...MOSTLY IFR VSBY/CIGS...TO START UP AT BOTH SITES BY MIDNIGHT. PERIOD OF HEAVIER SNOW/POTENTIAL VLIFR CONDITIONS DEVELOPS LATE TONIGHT AT CMX AS THE SFC TROUGH SHIFTS THROUGH...THEN BY LATE SUNDAY MORNING AT SAW. IN THE WAKE OF THE HEAVY SNOW THROUGH SUNDAY AFTN...EXPECT VLIFR/LIFR CONDITIONS AT BOTH SITE DUE TO LK EFFECT SNOW...STRONG NRLY WINDS GUSTING TO 35 KNOTS...AND SIGNIFICANT BLOWING SNOW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... THE WINDS ON LAKE SUPERIOR WILL INCREASE TONIGHT OUT OF THE NORTHEAST. THIS IS DUE TO INTERACTION BETWEEN THE RIDGE OF HIGH PRESSURE REMAINING OVER NORTHERN ONTARIO...AND A LOW PRESSURE OVER THE OHIO RIVER VALLEY. WINDS SHOULD INCREASE FURTHER ON SUNDAY TO NORTH WINDS 25 TO 30 KNOTS WITH FREQUENT GALE FORCE GUSTS TO 35 OR 40 KT AS THE LOW CONTINUES TO DEEPEN AND COLD AIR RUSHES SOUTH OUT OF CANADA. THIS COLD AIR WILL ALSO HELP PRODUCE HEAVY FREEZING SPRAY. THE WINDS WILL GRADUALLY DIMINISH SUNDAY NIGHT AND GALE FORCE GUSTS WILL DIMINISH AS THE LOW PULLS AWAY. THE HIGH PRESSURE RIDGE WILL CROSS UPPER MICHIGAN LATE MONDAY INTO MONDAY NIGHT...BUT WINDS ON SUPERIOR SHOULD STILL STAY WEST TO SOUTHWEST AT 15 TO 30 KNOTS. A LOW PRESSURE SYSTEM WILL DEVELOP OVER THE CENTRAL PLAINS ON TUESDAY AND MOVE INTO THE UPPER GREAT LAKES TUESDAY NIGHT AND WEDNESDAY. WINDS SHOULD STAY BELOW GALES CRITERIA WITH THIS SYSTEM...THOUGH THE SOUTHERLY WINDS AHEAD OF IT ON TUESDAY AND THE NORTHWEST WINDS BEHIND ON IT ON WEDNESDAY WILL CONTINUE TO RANGE FROM 15 TO 30 KNOTS. && UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 7 AM EST MONDAY FOR MIZ004-013-084. WINTER WEATHER ADVISORY FROM 1 AM SUNDAY TO 7 AM EST MONDAY FOR MIZ007-014-085. WINTER STORM WARNING FROM 7 PM THIS EVENING TO 1 AM EST MONDAY FOR MIZ001-003. WINTER STORM WARNING FROM 7 PM EST /6 PM CST/ THIS EVENING TO 7 AM EST /6 AM CST/ MONDAY FOR MIZ002-009. WINTER STORM WARNING FROM 1 AM SUNDAY TO 7 AM EST MONDAY FOR MIZ005-006. WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST SUNDAY FOR MIZ010>012. LAKE SUPERIOR... GALE WARNING FROM 11 AM SUNDAY TO MIDNIGHT EST SUNDAY NIGHT FOR LSZ265>267. GALE WARNING FROM 7 AM TO 11 PM EST SUNDAY FOR LSZ263-264. GALE WARNING FROM 1 PM SUNDAY TO MIDNIGHT EST SUNDAY NIGHT FOR LSZ248>251. GALE WARNING FROM 10 AM TO 11 PM EST SUNDAY FOR LSZ242>245. GALE WARNING FROM 7 AM EST /6 AM CST/ TO 4 PM EST /3 PM CST/ SUNDAY FOR LSZ162. HEAVY FREEZING SPRAY WARNING FROM 7 AM EST /6 AM CST/ SUNDAY TO 7 AM EST /6 AM CST/ MONDAY FOR LSZ162-263-264. LAKE MICHIGAN... GALE WATCH SUNDAY EVENING FOR LMZ221-250. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...JLB AVIATION...JLA MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 415 PM EST SAT DEC 20 2008 SYNOPSIS... WATER VAPOR IMAGE AND RUC SHOWING A CLOSED LOW OVER NORTHWEST NORTH DAKOTA...PUSHING A RIDGE OVER WESTERN ONTARIO AND THE UPPER GREAT LAKES REGIONS. WEAK SHORTWAVES ARE BEING EJECTED OUT AHEAD OF THIS LOW AND ARE OVER MANITOBA AND MINNESOTA. SURFACE ANALYSIS DEPICTS AN INVERTED TROUGH STRETCHING FROM WESTERN IOWA NORTH INTO SOUTHEAST MANITOBA. THIS TROUGH IS SEPARATING A RIDGE OVER EASTERN ONTARIO FROM A HIGH OVER SOUTHWEST CANADA. ANOTHER SIGNIFICANT LOW IS OVER THE MIDDLE MISSISSIPPI RIVER VALLEY. A STATIONARY FRONT STRETCHES EAST FROM THIS LOW ACROSS THE SOUTHEASTERN STATES. && .SHORT TERM...TONIGHT AND SUNDAY. A STRONG LIFT PER 700-500MB Q-VECTOR DIVERGENCE AND DEEP MOISTURE THROUGH 20KFT THIS EVENING WILL ALLOW FOR 3 TO 4 INCHES OF SYNOPTIC SNOW TO FALL TONIGHT AS INVERTED TROUGH SHIFTS INTO FORECAST AREA AFTER 00Z. MAIN SNOW WON`T ARRIVE UNTIL AFT 00Z. A SURFACE LOW EJECTING OUT OF TEXAS THIS AFTERNOON WILL MERGE WITH THE TROUGH OVER THE LOWER GREAT LAKES SUNDAY MORNING. AS THIS HAPPENS THE RESULTING NORTHEASTERLY FLOW WILL ALLOW FOR HEAVY LES TO DEVELOP OVER NORTH CENTRAL AND WESTERN UPPER MICHIGAN. WINTER STORM WARNINGS REMAIN IN EFFECT FOR GOGEBIC/ONTONAGON/MARQUETTE/ALGER. ADVISORIES WILL KEEP ELSEWHERE AS NOT ENOUGH CONFIDENCE IN REACHING WARNING CRITERIA. TONIGHT THROUGH SUNDAY UP TO 8 INCHES OR MORE OF LES MAY FALL ACROSS THE HIGHER TERRAIN OF MARQUETTE COUNTY...AREAS OF KEWEENAW COUNTY AND INTO WESTERN GOGEBIC/ONTONAGON COUNTIES. THIS IS FURTHER SUPPORTED BY THE LOCAL WRF MODEL. CONCERN ABOUT POSSIBLE LAKE ENHANCED SNOW SHOWERS OVER MENOMINEE COUNTY...FOR POSSIBLE NEED FOR WARNING. HOWEVER...WRF/NAM12 SHOWING WINDS BACKING NORTH SHORTLY AFTER SUNRISE OVER SOUTHERN COUNTIES...DRIER AIR ADVECTING IN...AND LACK OF TERRAIN SUPPORT OF LES. THUS WILL STAY WITH THE CURRENT ADVISORIES FOR THAT AREA TOO. AFTER COORDINATED WITH GRB DECIDED TO STAY WITH THE ADVISORY FOR NOW. && .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) SUN NIGHT...EXPECT TRANSITION FROM LAKE ENHANCED TO LAKE EFFECT SNOW WITH CONTINUED VERY FAVORABLE SNOW GROWTH PARAMETERS WITH GOOD UPWARD MOTION IN THE DGZ THROUGH 06Z/MON. EVEN THOUGH SNOW/WATER RATIOS SHOULD BE AOA 30/1 DURING THE EVENING...WITH CONTINUED WINDY CONDITIONS...FRACTURING AND DRIFTING SHOULD REDUCE ACTUAL/OBSERVED SNOW TOTALS. NEVERTHELESS...ADDITIONAL AMOUNTS IN THE 2 TO 6 INCH RANGE ARE EXPECTED FOR N WIND FAVORED SNOWBELTS...WITH THE GREATEST AMOUNTS IN THE HIGHER TERRAIN WHERE STRONG UPSLOPE LIFT WILL OCCUR. OVERNIGHT...WITH BACKING WINDS...LOWERING INVERSION HEIGHTS/ EXIT OF DEEPER MOISTURE...SNOWFALL RATES WILL TAPER OFF AND LES SHOULD SHIFT TOWARD NW FLOW FAVORED AREAS. BLOWING SNOW SHOULD ALSO SUBSIDE OVERNIGHT AS THE GRADIENT WEAKENS IN THE WAKE OF THE DEPARTING LOW. AS WINDS BACK TO WRLY BY MIDDAY MON...LES WILL SHIFT INTO THE KEWEENAW AND FAR NE UPPER MI WHILE RELATIVELY TRANQUIL WEATHER PREVAILS ACROSS THE REST OF THE CWA. BEFORE CLOUDS THICKEN MON NIGHT IN ADVANCE OF THE NEXT SHRTWV...TEMPS MAY PLUMMET CLOSER TO LOWER NAM GUIDANCE VALUES NEAR -10F WELL INLAND. TUE...MDLS WERE IN GOOD AGREEMENT WITH THE NEXT MID LEVEL AND SFC TROUGH THAT WILL MOVE THROUGH THE REGION BRINGING ANOTHER ROUND OF SNOW. MDLS TEMP/UVV/RH PROFILE SUGGEST SNOW/WATER MAY BE RELATIVELY LOW WITH BEST LIFT ABOVE THE DGZ. SO WITH QPF VALUES IN THE 0.10 TO 0.20 RANGE AND SNOW/WATER RATIOS NEAR 15/1 ACCUMULATIONS MAINLY IN THE 1 TO 3 INCH RANGE WOULD BE EXPECTED. WED...SIGNIFICANT UNCERTAINTY REMAINS WITH THE POTENTIAL FOR ANOTHER STRONGER SHRTWV AND SFC LOW DEVELOPMENT. THE 12Z ECMWF AND UKMET FAVORED POTENTIAL FOR HEAVIER SNOW WITH THIS FEATURE WHILE THE GFS AND CMC DID NOT. IF THE EURO MODELS VERIFY...ANOTHER HEAVY SNOW EVENT WOULD BE EXPECTED WITH FAVORABLE SCENARIO FOR LAKE ENHANCED SNOW IN N CNTRL UPPER MI. THU-SAT...THE FCST GENERALLY FOLLOWED THE HPC PREFERRED ECMWF/CMC MDLS SCENARIO WHICH ALSO HAD DECENT SUPPORT FROM THE 12Z GFS ENSEMBLES. THE 06Z/12Z WAS AN OUTLIER IN BRINGING A WEAKER NRN STREAM SYSTEM THROUGH THE NRN TIER AND DELAYING THE EJECTION OF A STRONGER SHRTWV FROM THE SW CONUS. SO...WITH A SW FLOW PATTERN AND STRONGER SE CONUS RIDGE...A SHRTWV AND SFC LOW TRACK THROUGH OR WEST OF CNTRL UPPER MI COULD BRING POTENTIAL FOR MIXED PCPN (SN/FZRA/PL/RA) AND A BRIEF WARMUP AOA FREEZING BY LATE FRI. .AVIATION (FOR THE 18Z TAF ISSUANCE)... A LAKE EFFECT SNOW BAND OFF BIG BAY AND THE KEWEENAW PENINSULA WILL PERSIST EARLY THIS AFTERNOON...WHICH MEANS THAT CMX WILL BE MAINLY IMPACT. MVFR FOR VSBYS/CIGS CONDITIONS ASSOCIATED WITH THE LAKE EFFECT CAN BE EXPECTED. VFR CONDITIONS WILL PERSIST AT SAW THROUGH THE AFTERNOON SINCE EAST WINDS ARE NOT FAVORABLE FOR LAKE EFFECT. DURING THE AFTERNOON AS WINDS VEER SOUTHEAST SO CEILINGS AT BOTH SITES SHOULD REMAINING MVFR. A LOW PRESSURE TROUGH AND ASSOCIATED SNOW TONIGHT OVER THE EASTERN DAKOTAS/WESTERN MINNESOTA WILL MOVE INTO UPPER MICHIGAN. VISIBILITIES HAVE GENERALLY BE IN THE IFR RANGE...AND HAVE GONE WITH THAT FOR THE TAFS. CIGS RANGE FROM MVFR TO IFR...WHICH THE IFR IS PROBABLY MORE LIKELY AT SAW SINCE CMX WILL BE ABLE TO STAY MORE MIXED IN THE LOW LEVELS FROM FLOW OFF LAKE SUPERIOR. HOWEVER...LATE IN THE NIGHT...THERE ARE INDICATIONS OF A SIGNIFICANT LAKE EFFECT BAND MOVING THROUGH THE KEWEENAW. LIFR WILL SET UP DURING THE MORNING AT BOTH LOCATIONS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... THE WINDS ON LAKE SUPERIOR WILL INCREASE TONIGHT OUT OF THE NORTHEAST. THIS IS DUE TO INTERACTION BETWEEN THE RIDGE OF HIGH PRESSURE REMAINING OVER NORTHERN ONTARIO...AND A LOW PRESSURE OVER THE OHIO RIVER VALLEY. WINDS SHOULD INCREASE FURTHER ON SUNDAY TO NORTH WINDS 25 TO 30 KNOTS WITH FREQUENT GALE FORCE GUSTS TO 35 OR 40 KT AS THE LOW CONTINUES TO DEEPEN AND COLD AIR RUSHES SOUTH OUT OF CANADA. THIS COLD AIR WILL ALSO HELP PRODUCE HEAVY FREEZING SPRAY. THE WINDS WILL GRADUALLY DIMINISH SUNDAY NIGHT AND GALE FORCE GUSTS WILL DIMINISH AS THE LOW PULLS AWAY. THE HIGH PRESSURE RIDGE WILL CROSS UPPER MICHIGAN LATE MONDAY INTO MONDAY NIGHT...BUT WINDS ON SUPERIOR SHOULD STILL STAY WEST TO SOUTHWEST AT 15 TO 30 KNOTS. A LOW PRESSURE SYSTEM WILL DEVELOP OVER THE CENTRAL PLAINS ON TUESDAY AND MOVE INTO THE UPPER GREAT LAKES TUESDAY NIGHT AND WEDNESDAY. WINDS SHOULD STAY BELOW GALES CRITERIA WITH THIS SYSTEM...THOUGH THE SOUTHERLY WINDS AHEAD OF IT ON TUESDAY AND THE NORTHWEST WINDS BEHIND ON IT ON WEDNESDAY WILL CONTINUE TO RANGE FROM 15 TO 30 KNOTS. && UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 7 AM EST MONDAY FOR MIZ004-013-084. WINTER WEATHER ADVISORY FROM 1 AM SUNDAY TO 7 AM EST MONDAY FOR MIZ007-014-085. WINTER STORM WARNING FROM 7 PM THIS EVENING TO 1 AM EST MONDAY FOR MIZ001-003. WINTER STORM WARNING FROM 7 PM EST /6 PM CST/ THIS EVENING TO 7 AM EST /6 AM CST/ MONDAY FOR MIZ002-009. WINTER STORM WARNING FROM 1 AM SUNDAY TO 7 AM EST MONDAY FOR MIZ005-006. WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST SUNDAY FOR MIZ010>012. LAKE SUPERIOR... GALE WARNING FROM 11 AM SUNDAY TO MIDNIGHT EST SUNDAY NIGHT FOR LSZ265>267. GALE WARNING FROM 7 AM TO 11 PM EST SUNDAY FOR LSZ263-264. GALE WARNING FROM 1 PM SUNDAY TO MIDNIGHT EST SUNDAY NIGHT FOR LSZ248>251. GALE WARNING FROM 10 AM TO 11 PM EST SUNDAY FOR LSZ242>245. GALE WARNING FROM 7 AM EST /6 AM CST/ TO 4 PM EST /3 PM CST/ SUNDAY FOR LSZ162. HEAVY FREEZING SPRAY WARNING FROM 7 AM EST /6 AM CST/ SUNDAY TO 7 AM EST /6 AM CST/ MONDAY FOR LSZ162-263-264. LAKE MICHIGAN... GALE WATCH SUNDAY EVENING FOR LMZ221-250. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...JLB AVIATION...DLG MARINE...DLG mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1228 PM EST SAT DEC 20 2008 .SYNOPSIS... WATER VAPOR IMAGE AND RUC SHOWING A CLOSED LOW OVER NORTHWEST NORTH DAKOTA...PUSHING A RIDGE OVER WESTERN ONTARIO AND THE UPPER GREAT LAKES REGIONS. WEAK SHORTWAVES ARE BEING EJECTED OUT AHEAD OF THIS LOW AND ARE OVER MANITOBA AND MINNESOTA. SURFACE ANALYSIS DEPICTS AN INVERTED TROUGH STRETCHING FROM WESTERN IOWA NORTH INTO SOUTHEAST MANITOBA. THIS TROUGH IS SEPARATING A RIDGE OVER EASTERN ONTARIO FROM A HIGH OVER SOUTHWEST CANADA. ANOTHER SIGNIFICANT LOW IS DEVELOPING OVER OKLAHOMA. A STATIONARY FRONT STRETCHES EAST FROM THIS LOW ACROSS THE SOUTHEASTERN STATES. && .SHORT TERM...THIS AFTERNOON. THE LOW WILL ONLY TREK SLOWLY ALONG THE NORTH DAKOTA/MANITOBA BORDER THIS AFTERNOON. A WEAK SHORTWAVE OVER MINNESOTA WILL MOVE LITTLE THIS AFTERNOON. THE SURFACE INVERTED TROUGH WILL SHIFT OVER THE UPPER MISSISSIPPI RIVER VALLEY...WHILE THE LOW OVER OKLAHOMA TRACKS ALONG THE FRONT AND INTO THE MIDDLE MISSISSIPPI RIVER VALLEY. Q-VECTOR CONVERGENCE ASSOCIATED WITH THE CLOSED LOW ALOFT AND ISENTROPIC ASCENT AHEAD OF THIS TROUGH WILL GENERATE SOME SNOW OVER WISCONSIN AND PARTS OF WESTERN U.P. THIS AFTERNOON. .LONG TERM... TONIGHT THROUGH WEDNESDAY...CURRENT THINKING IS THAT BY THIS EVENING STRONG LIFT PER 700-500MB DIV Q FIELDS AND DEEP MOISTURE THROUGH 20KFT WILL ALLOW FOR 3 TO 4 INCHES OF SYNOPTIC SNOW TO FALL TONIGHT AS INVERTED TROUGH SHIFTS INTO FA AFTER 00Z. MAIN SNOW WON/T ARRIVE IN MOST PLACE TILL AFT 00Z. A SFC LOW EJECTING OUT OF TEXAS THIS AFTN WILL MERGE WITH THE IV TROUGH SOMEWHERE OVER LAKE HURON SUN AFTN. AS THIS HAPPENS THE RESULTING NORTHEASTERLY FLOW WILL ALLOW FOR HEAVY LES TO DEVELOP OVER NORTH CENTRAL AND WESTERN UPPER MICHIGAN. WENT WITH WINTER STORM WARNINGS FOR GOGEBIC/ONTONAGON/MARQUETTE/ALGER. OPTED FOR ADVISORIES ELSEWHERE AS NOT ENOUGH CONFIDENCE IN REACHING WARNING CRITERIA...THOUGH COULD ENVISION MENOMINEE BEING UPGRADED AS THEY MAY SEE SOME LAKE ENHANCEMENT OFF LM. TONIGHT THROUGH SUNDAY UP TO 8 INCHES OR MORE OF LES MAY FALL ACROSS THE HIGHER TERRAIN OF MARQUETTE COUNTY...AREAS OF KEWEENAW COUNTY AND INTO WESTERN GOGEBIC/ONTONAGON COUNTIES. BY SUNDAY NIGHT THE SYSTEM CONTINUES TO TRACK EAST AND MERGES WITH A COASTAL LOW WHICH DEEPENS TO AROUND 970MB OVER MAINE ON MONDAY AFTN. THIS WILL ALLOW WINDS TO BACK ON SUNDAY NIGHT INTO EARLY MONDAY...SHIFTING HIGHER LES POPS TO AREAS FAVORED BY A NW WIND. AMOUNTS ARE EXPECTED TO BE LIGHT THOUGH AS DRIER AIR FILTERS IN AND INVERSION HEIGHTS FALL. HIGH PRESSURE THEN SETTLES IN OVER THE FA ON MONDAY INTO TUESDAY MORNING. EVEN THOUGH SKIES MAY CLEAR ON MONDAY NIGHT...INCREASING WINDS BY MIDNIGHT MAY NOT ALLOW TEMPERATURES TO DROP TOO MUCH...RIGHT NOW HAVE LOWS REMAINING IN THE SINGLE DIGITS BELOW ZERO ACROSS THE WEST AND NEAR ZERO EAST. IF RETURN FLOW IS DELAYED AS THE HIGH SHIFTS TO THE EAST ON MONDAY NIGHT...TEMPERATURES WILL DROP MUCH LOWER AS AIRMASS IS QUITE DRY AS NOTED BY PWAT/S LESS A TENTH OF AN INCH. NEXT SYSTEM THEN MOVES IN ON TUESDAY...OPTED TO INCREASE POPS TO LIKELY AS MEDIUM RANGE GUIDANCE SHOWS GOOD CONTINUITY. RIGHT NOW THIS LOOKS TO BE AN ADSRY EVENT AT BEST SLR LOOK TO BE AROUND 15/18:1...GIVEN LACK OF LIFT WITHIN DENDRITIC ZONE. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... A LAKE EFFECT SNOW BAND OFF BIG BAY AND THE KEWEENAW PENINSULA WILL PERSIST EARLY THIS AFTERNOON...WHICH MEANS THAT CMX WILL BE MAINLY IMPACTE. MVFR FOR VSBYS/CIGS CONDITIONS ASSOCIATED WITH THE LAKE EFFECT CAN BE EXPECTED. VFR CONDITIONS WILL PERSIST AT SAW THROUGH THE AFTERNOON SINCE EAST WINDS ARE NOT FAVORABLE FOR LAKE EFFECT. DURING THE AFTERNOON AS WINDS VEER SOUTHEAST SO CEILINGS AT BOTH SITES SHOULD REMAINING MVFR. A LOW PRESSURE TROUGH AND ASSOCIATED SNOW TONIGHT OVER THE EASTERN DAKOTAS/WESTERN MINNESOTA WILL MOVE INTO UPPER MICHIGAN. VISIBILITIES HAVE GENERALLY BE IN THE IFR RANGE...AND HAVE GONE WITH THAT FOR THE TAFS. CIGS RANGE FROM MVFR TO IFR...WHICH THE IFR IS PROBABLY MORE LIKELY AT SAW SINCE CMX WILL BE ABLE TO STAY MORE MIXED IN THE LOW LEVELS FROM FLOW OFF LAKE SUPERIOR. HOWEVER...LATE IN THE NIGHT...THERE ARE INDICATIONS OF A SIGNIFICANT LAKE EFFECT BAND MOVING THROUGH THE KEWEENAW. LIFR WILL SET UP DURING THE MORNING AT BOTH LOCATIONS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... LOOK FOR WINDS ON LAKE SUPERIOR TO STAY AT OR BELOW 20 KT FOR MOST OF TODAY...THEN INCREASE TONIGHT OUT OF THE NORTHEAST. THIS IS DUE TO A RIDGE OF HIGH PRESSURE REMAINING OVER NORTHERN ONTARIO...AND A LOW PRESSURE TROUGH OVER THE EASTERN DAKOTAS CONSOLIDATING AND DEEPENING INTO A LOW OVER NORTHERN LOWER MICHIGAN BY SUNDAY MORNING. WINDS SHOULD INCREASE FURTHER ON SUNDAY TO NORTH GALES TO 35 OR 40 KT AS THE LOW CONTINUES TO DEEPEN AND COLD AIR RUSHES SOUTH OUT OF CANADA. THIS COLD AIR WILL ALSO HELP PRODUCE HEAVY FREEZING SPRAY. LOOK FOR WINDS TO GRADUALLY DIMINISH SUNDAY NIGHT BELOW GALES AS THE LOW PULLS AWAY. A HIGH PRESSURE RIDGE WILL CROSS UPPER MICHIGAN LATE MONDAY INTO MONDAY NIGHT...BUT WINDS ON SUPERIOR SHOULD STILL STAY WEST TO SOUTHWEST AT 15 TO 30 KNOTS. A LOW PRESSURE SYSTEM IS EXPECTED TO DEVELOP OVER THE CENTRAL PLAINS ON TUESDAY AND MOVE INTO THE UPPER GREAT LAKES TUESDAY NIGHT AND WEDNESDAY. NO GALES ARE PLANNED WITH THIS SYSTEM...THOUGH THE SOUTHERLY WINDS AHEAD OF IT ON TUESDAY AND THE NORTHWEST WINDS BEHIND ON IT ON WEDNESDAY WILL CONTINUE TO RANGE FROM 15 TO 30 KNOTS. && UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 7 AM EST MONDAY FOR MIZ004-013-084. WINTER WEATHER ADVISORY FROM 1 AM SUNDAY TO 7 AM EST MONDAY FOR MIZ007-014-085. WINTER STORM WARNING FROM 7 PM THIS EVENING TO 1 AM EST MONDAY FOR MIZ001-003. WINTER STORM WARNING FROM 7 PM EST /6 PM CST/ THIS EVENING TO 7 AM EST /6 AM CST/ MONDAY FOR MIZ002-009. WINTER STORM WARNING FROM 1 AM SUNDAY TO 7 AM EST MONDAY FOR MIZ005-006. WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST SUNDAY FOR MIZ010>012. LAKE SUPERIOR... GALE WARNING FROM 11 AM SUNDAY TO MIDNIGHT EST SUNDAY NIGHT FOR LSZ265>267. GALE WARNING FROM 7 AM TO 11 PM EST SUNDAY FOR LSZ263-264. GALE WARNING FROM 1 PM SUNDAY TO MIDNIGHT EST SUNDAY NIGHT FOR LSZ248>251. GALE WARNING FROM 10 AM TO 11 PM EST SUNDAY FOR LSZ242>245. GALE WARNING FROM 7 AM EST /6 AM CST/ TO 4 PM EST /3 PM CST/ SUNDAY FOR LSZ162. HEAVY FREEZING SPRAY WARNING FROM 7 AM EST /6 AM CST/ SUNDAY TO 7 AM EST /6 AM CST/ MONDAY FOR LSZ162-263-264. LAKE MICHIGAN... GALE WATCH SUNDAY EVENING FOR LMZ221-250. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...PEARSON AVIATION...DLG MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1226 AM EST SAT DEC 20 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAF ISSUANCE .UPDATE... OPTED TO ISSUE LES WRNG FOR WRN ALGER COUNTY AND EXTEND WRNG FOR MQT COUNTY/ADVY FOR BARAGA COUNTY WITH PERSISTENT...WELL DVLPD LES BAND NOTED JUST OFFSHORE STREAMING INTO WRN ALGER COUNTY/ERN MQT COUNTY. 88D ESTIMATES SHOW 0.08"/HR WATER EQUIVALENT PCPN UNDER THIS BAND. CONSIDERING OBSVD 40:1-50:1 SN/WATER RATIOS AND NEARLY UNIDIRECTIONAL NE FLOW SHOWN ON MQT VWP THRU 5K-6K FT MSL...SUSPECT BAND WL MAINTAIN INTENSITY FOR AT LEAST THE NEXT COUPLE OF HRS AND DROP SN AT THE RATE OF 1-2"/HR AT SOME PLACES. AS SFC-H925 WINDS DIMINISH TOWARD 06Z AND VEER MORE E...SUSPECT BANDS WL WEAKEN WITH SHSN CONSOLIDATING NEAR LK SUP IN MQT COUNTY IN MORE FOCUSED LLVL CNVGC BTWN DVLPG LAND BREEZE AND VORTEX LIKELY TO DVLP OVER SCNTRL LK SUP PER HIER RES NAM/REG GEM/LOCAL WRF-ARW MODELS. IF THIS VORTEX DOES NOT DVLP...MORE ELY FLOW MAY BRING SOME HEAVIER LES BACK INTO THE KEWEENAW ZNS. BUT FCST VORTEX DVLPMNT WOULD INCRS SHEAR AND MORE UNFVRBL NE WIND COMPONENT. && .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED THAT THE VIGOROUS SHORTWAVE TROUGH THAT BROUGHT HEAVY SNOW TO WI/MI WAS QUICKLY MOVING EASTWARD THROUGH THE ERN GREAT LAKES. THE NEXT SIGNIFICANT MID/UPPER LEVEL UPSTREAM TROUGH EXTENDED FROM ALBERTA INTO THE NRN ROCKIES. LOW LEVEL NE FLOW PREVAILED BTWN SFC HIGH PRES OVER NRN ONTARIO AND LOW PRES OVER WRN PA. THIS HAS KEPT LES GOING INTO N CNTRL UPPER MI THIS AFTERNOON. THE STRONGEST BANDS WERE NOTED OVER ERN MARQUETTE COUNTY AND THROUGH KEWEENAW BAY TO NEAR LANSE. VIS AND RADAR LOOPS SUGGEST WEAK TROF HAS ALSO HELPED KEEP FOCUS OF LOW LEVEL CONV NEAR ERN MARQUETTE COUNTY. && .SHORT TERM...(TONIGHT AND SATURDAY) WITH THE PROGRESSIVE PATTERN...AN INVERTED TROUGH WILL DEVELOP OVER THE NRN PLAINS AND THE NRN ONTARIO HIGH WILL SHIFT TO THE EAST...RESULTING IN VEERING WINDS TONIGHT. THE NAM HAS HANDLED THE LOW LEVEL WIND FIELD PATTERN AFFECTING THE LES BEST. SO...EXPECT THE LES TO CONTINUE INTO N CNTRL UPPER MI THIS EVENING WITH CONTINUED NE FLOW BEFORE SHIFT TO E AND ESE WINDS LATE TONIGHT. EVEN WITH MAINLY MULTIPLE WIND PARALLEL BANDS...POTENTIAL REMAINS FOR ANOTHER 1 TO 3 INCHES OF SNOW INTO EARLY THIS EVENING...ESPECIALLY NEAR KEWEENAW BAY AND INTO THE HIGHER TERRAIN FROM NEGAUNEE TO SKANDIA. WITH THE TREND MORE TOWARD VARIABLE OR ESE WINDS LATE...LES SHOULD SHIFT TOWARD THE KEWEENAW PENINSULA. CONFIDENCE IS LOW WITH SNOW AMOUNTS FOR THIS AREA...GIVEN THE WEAK WIND FIELDS AND INCONSISTENT MODEL PERFORMANCE. LIGHT SNOW AHEAD OF THE MID/UPPER LEVEL LOW AND SFC TROUGH IS EXPECTED TO SPREAD INTO W UPPER MI DURING THE AFTERNOON WITH SNOW ACCUMULATION AMOUNTS OF AN INCH OR TWO. .LONG TERM (SATURDAY NIGHT THROUGH NEXT FRIDAY)... HEAVY SNOW POTENTIAL SAT NIGHT THROUGH SUN NIGHT IS MAIN CONCERN UPPER LOW CURRENTY OVR THE NRN US ROCKIES REGION ARRIVES OVR THE UPR GREAT LAKES LATE SATURDAY INTO SATURDAY NIGHT. TRACK OF H7-H5 LOWS ACROSS NRN WI COUPLED WITH INCREASING LOW-LEVEL CONVERGENCE FM EAST TO WEST ORIENTED SFC TROUGH FAVORS CWA FOR ACCUMULATING SNOW. THIS REALLY IS NOT IN QUESTION. SNOW AMOUNTS ARE THE MAIN ISSUE. EXPECT THE SYNOPTIC SYSTEM TO REMAIN PROGRESSIVE AS PRIMARY JET ENERGY IS SLIDING OUT AHEAD OF THE UPR LOW...KEEPING THE UPR LOW MORE OPEN...AND NOT FAVORING SIGNIFICANT DEEPENING ON THE LARGE SCALE. LOOKING AT THE SYNOPTIC SNOW ALONE...NAM/GFS FORECAST SOUNDINGS ACROSS SOUTHERN HALF OF THE CWA...IMT-ESC-ISQ...SHOW PLENTY OF MOISTURE BUT THE MAJORIFY OF THE STRONGER OMEGA/LIFT IS LOCATED ABOVE THE MAXIMUM SNOW GROWTH ZONE. SETUP FAVORS A WEALTH OF HIGHER DENSITY CRYSTALS INSTEAD OF LOW DENSITY DENDRITES. USED SNOW RATIOS FM 10-15:1. SUPPOSE THERE IS ALSO A SMALL POTENTIAL OF LK ENHANCEMENT OFF LK MICHIGAN WITH ERLY FLOW. NAM REALLY HINTED AT THIS POTENTIAL BUT THAT MODEL ALSO SHOWS INCREASING SHEAR IN THE SUB H85 LAYER...MAINLY AFTER 06Z SUNDAY. BASICALLY...DUE TO QUICK MOVEMENT OF THE SYSTEM AND LOWER SNOW RATIOS...SEEMS LIKE THIS IS ON TRACK TO BE A HIGH-END ADVY EVENT AWAY FM LAKE SUPERIOR. EVEN ADVY SNOW WILL BE WELCOME OVR THE SRN CWA GIVEN THE ONGOING DROUGHT PLAUGING THAT AREA. ONE THING TO WATCH THOUGH. 12Z NAM AND 12Z ECMWF SHOW A SLOWER MOVEMENT TO THE UPR LEVEL TROUGH/SFC TROUGH...RESULTING IN A LONGER DURATION OF SNOW. IF THESE FEATURES HANG UP MORE...THEN THERE WOULD NEED TO BE AN INCREASE OF SNOW FOR THE SERN/ERN CWA. AS ALLUDED TO BEFORE...DUE TO EXPECTED PROGRESSIVE NATURE OF THE SYSTEM...FAVORED QUICKER SOLUTION AND NOT AS MUCH SNOW MAIN IMPACT FM SYSTEM AT THIS TIME LOOKS TO BE THE INCREASING LAKE ENHANCEMENT FOR WRN CWA SATURDAY NIGHT AND THE NCNTRL SUNDAY INTO SUNDAY NIGHT. LEADING OFF...ERLY LOW-LEVEL WINDS WITH H85 TEMPS AROUND -15C SATURDAY NIGHT TARGET THE KEWEENAW PENINSULA FOR THE HEAVIEST SNOW. UNLIKE THE SRN CWA...SOUNDINGS OVR THE KEWEENAW ALSO INDICATE MOST OF THE LIFT OCCURRING IN THE BEST SNOW GROWTH ZONE. H95 CONVERGENCE INCREASES SATURDAY EVENING AND PERISTS INTO SUNDAY MORNING. LATER SUNDAY MORNING INTO SUNDAY AFTERNOON...SFC-H85 WINDS BACK MORE NRLY WHICH BRINGS FAR WRN CWA AND NCNTRL CWA INTO FOLD FOR HEAVIER LK EFFECT. SOUNDINGS QUITE FAVORABLE WITH DEEP MOISTURE THROUGH 20KFT AND STRONG OMEGA/LIFT RIGHT WITHIN THE SNOW GROWTH ZONE. CROSSHAIR SIGNATURE SHOWS UP NICELY ON THE MQT SOUDNINGS... SUGGESTING INTENSE SNOW RATES AND HIGH SNOW RATIOS...PROBABLY SURGING TOWARD 30:1 BY SUNDAY AFTN. MAIN NEGATIVE FOR SIGNIFICANT ACCUMS DURING THE PERIOD WILL BE FRATURING OF SNOWFLAKES AS WINDS IN THE MIXED LAYER ARE INCREASING TO 25-35 KNOTS. STILL...UPSLOPE AREAS OF WRN AND NCNTRL CWA SHOULD DO WELL WITH 350-010 WIND DIRECTION. POTENTIAL FOR HEAVIER LK EFFECT SNOW AND STRONG WINDS/BLSN JUSTIFIES WINTER STORM WATCH FOR GOGEBIC THROUGH KEWEENAW AND FOR MARQUETTE COUNTY. SNOW AMOUNTS AWAY FM THESE AREAS SHOULD REMAIN BLO WARNING CRITERIA AND ANTICIPATE ADVY NEEDED ACROSS REST OF THE CWA. IF THE UPR LOW SLOWS DOWN THOUGH...WE WOULD NEED WATCHES FOR MUCH OF THE SOUTH AND ERN CWA. EXPECT LINGERING LK EFFECT THROUGH MONDAY BUT LOW-LEVEL WINDS WILL STEADILY BACK SW...ALLOWING HEAVIER SNOW TO BECOME MORE TRANSIENT. BY LATE AFTN...EXPECT MOST OF THE SNOW TO RESIDE OVR THE KEWEENAW PENINSULA. WRLY FLOW LK EFFECT SHOULD CONTINUE INTO MON NIGHT OVR THE KEWEENAW. THOUGH...INCREASING LOW-LEVEL SHEAR AND DECREASING MOISTURE WILL BE NEGATIVE FACTORS. LOW PRESSURE TROUGH EJECTING INTO THE CENTRAL PLAINS LIFTS ACROSS GREAT LAKES TUESDAY/TUESDAY NIGHT. HPC PREFEREED THE WEAKER/SLOWER GFS AS THE ECMWF WAS A STRONGER AND PROGRESSIVE OUTLIER. NUDGED POPS UPWARD EAST DUE TO BETTER MOISTURE TRANSPORT INTO THE SYSTEM AND POTENTIAL FOR SOME ENHANCEMENT OFF LK MICHIGAN. CYCLONIC FLOW/LK EFFECT CONTINUES IN THE WAKE OF THE THE TUESDAY LOW PRESSURE TROUGH...ESPECIALLY IN THE AREAS ALONG LK SUPERIOR FAVORED BY NW LOW-LEVEL FLOW. INTERESTING THAT NOW THE 12Z GFS AND ECMWF POINT TO ANOTHER WAVE OF LOW PRESSURE WITH MORE SYSTEM SNOW NEXT WEDNESDAY. WOULD STILL EXPECT THE HIGHEST POPS CLOSER TO LAKE SUPERIOR WITH ADDED BENEFIT FM ONSHORE FLOW. HIGH PRESSURE RIDGE THEN CROSSES THE UPR GREAT LAKES ON CHRISTMAS DAY. OTHER THAN LINGERING LK EFFECT FOR W/SW FLOW AREAS EARLY ON...SHOULD SEE TRANQUIL WEATHER. QUIET WEATHER WILL NOT LAST THOUGH. BY FRIDAY...UPPER TROUGH DEEPENS OVR WRN CONUS WHILE RIDGE POPS UP OVR ERN UNITED STATES. SWRLY FLOW ALOFT BRINGS ANOTHER LOW PRESSURE INTO THE GREAT LAKES. DECENT AGREEMENT FM GFS/ECMWF/CANADIAN THAT A WOUND UP SFC LOW WILL LIFT TOWARD UPR MI FRI/SAT. IF THIS OCCURS...WOULD HAVE MIXED PCPN CONCERNS AS WARMER AIR STREAMS INTO ERN HALF OF UPR MI. DID NOT WANT TO JUMP ON THE POTENTIAL FOR RAIN QUITE YET AS A COUPLE PREVIOUS LOW PRESSURE SYSTEMS THIS MONTH WERE FORECAST TO TRACK FARTHER NORTH THAN ENDED UP HAPPENING. NO MATTER WHAT... PATTERN STAYS ACTIVE WITH WRN TROUGH/ERN RIDGE PERSISTING AND SIGNIFICANT LOW PRESSURE SYSTEMS AFFECTING THE REGION INTO THE FINAL WEEK OF 2008. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT IFR/MVFR CONDITIONS AT SAW TO TREND TOWARD VFR EARLY THIS MRNG WITH FCST WEAKENING/VEERING WINDS TO MORE E CAUSING LES TO FOCUS CLOSER TO THE LK SUP SHORE. MVFR CIGS ARE LIKELY TO RETURN ON SAT AFTN WITH UPSLOPE SE FLOW OFF LK MI. ARRIVAL OF SN AHEAD OF NEXT LO PRES TO IMPACT THE UPR GRT LKS WL BRING A RETURN OF IFR VSBY THIS EVNG. UNFAVORABLE NE FLOW AT CMX WL TEND TO VEER MORE E EARLY THIS MRNG...SO EXPECT SOME LES TO DVLP TOWARD SUNRISE. BUT DVLPMNT OF VORTEX NEAR MQT WL LIKELY DISRUPT THIS FLOW/INCRS SHEAR AND KEEP LES INTENSITY IN CHECK. OVERALL...PLAN ON PREDOMINANT MVFR CIGS OVERNGT WITH LOWER MVFR VSBYS PSBL AFT 09Z. LATER THIS MRNG...HIER RES MODELS SHOW VORTEX WEAKENING WITH A PD OF UNIDIRECTIONAL ESE SFC-H925 FLOW CAUSING A BETTER CHC OF LES AND IFR VSBYS. AS THIS FLOW VEERS MORE SE IN THE AFTN WITH SHORTER OVERWATER FETCH/ DOWNSLOPE OFF HURON MTNS...SUSPECT LES INTENSITY TO DIMINISH. ARRIVAL OF SN AHEAD OF NEXT LO PRES TO IMPACT THE UPR GRT LKS WL BRING MVFR CONDITIONS THIS EVNG. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... AS LOW PRESSURE OVER WESTERN PA MOVES OFF THE EAST COAST THIS EVENING...NE WINDS WILL CONTINUE TO DIMINISH. NRLY GALE FORCE WINDS ARE EXPECTED SUNDAY AS A LOW PRESSURE TROUGH OVER MINNESOTA SATURDAY EVENING CONSOLIDATES INTO A LOW PRESSURE AREA AND DEEPENS AS IT CROSSES LOWER MICHIGAN. IN ADDITION TO THE GALES FROM THE LOW PRESSURE SYSTEM...HEAVY FREEZING SPRAY IS LIKELY AS COLD AIR IS DRAWN SOUTH OUT OF CENTRAL CANADA. LOOK FOR THE HEAVY FREEZING SPRAY AND WINDS TO DIMINISH SUNDAY NIGHT AND BACK WESTERLY FOR MONDAY...BUT WIND SPEEDS WILL STILL REMAIN BETWEEN 15 AND 30 KNOTS. NO OTHER GALES ARE EXPECTED DURING THE REST OF THE FORECAST PERIOD. && UPPER MICHIGAN... WINTER STORM WATCH FROM SATURDAY EVENING THROUGH LATE SUNDAY NIGHT FOR MIZ001-003. LAKE EFFECT SNOW ADVISORY UNTIL 1 AM EST SATURDAY FOR MIZ004. WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH MONDAY MORNING FOR MIZ002-009. LAKE EFFECT SNOW WARNING UNTIL 5 AM EST SATURDAY FOR MIZ005. WINTER STORM WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY MORNING FOR MIZ005. LAKE SUPERIOR... GALE WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY MORNING FOR LSZ264-266. GALE WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR LSZ162- 263. LAKE MICHIGAN...NONE. && $$ UPDATE...KC SYNOPSIS/SHORT TERM...JLB LONG TERM...JLA AVIATION...KC MARINE...JLB mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 710 PM EST FRI DEC 19 2008 .UPDATE... OPTED TO ISSUE LES WRNG FOR WRN ALGER COUNTY AND EXTEND WRNG FOR MQT COUNTY/ADVY FOR BARAGA COUNTY WITH PERSISTENT...WELL DVLPD LES BAND NOTED JUST OFFSHORE STREAMING INTO WRN ALGER COUNTY/ERN MQT COUNTY. 88D ESTIMATES SHOW 0.08"/HR WATER EQUIVALENT PCPN UNDER THIS BAND. CONSIDERING OBSVD 40:1-50:1 SN/WATER RATIOS AND NEARLY UNIDIRECTIONAL NE FLOW SHOWN ON MQT VWP THRU 5K-6K FT MSL...SUSPECT BAND WL MAINTAIN INTENSITY FOR AT LEAST THE NEXT COUPLE OF HRS AND DROP SN AT THE RATE OF 1-2"/HR AT SOME PLACES. AS SFC-H925 WINDS DIMINISH TOWARD 06Z AND VEER MORE E...SUSPECT BANDS WL WEAKEN WITH SHSN CONSOLIDATING NEAR LK SUP IN MQT COUNTY IN MORE FOCUSED LLVL CNVGC BTWN DVLPG LAND BREEZE AND VORTEX LIKELY TO DVLP OVER SCNTRL LK SUP PER HIER RES NAM/REG GEM/LOCAL WRF-ARW MODELS. IF THIS VORTEX DOES NOT DVLP...MORE ELY FLOW MAY BRING SOME HEAVIER LES BACK INTO THE KEWEENAW ZNS. BUT FCST VORTEX DVLPMNT WOULD INCRS SHEAR AND MORE UNFVRBL NE WIND COMPONENT. && .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED THAT THE VIGOROUS SHORTWAVE TROUGH THAT BROUGHT HEAVY SNOW TO WI/MI WAS QUICKLY MOVING EASTWARD THROUGH THE ERN GREAT LAKES. THE NEXT SIGNIFICANT MID/UPPER LEVEL UPSTREAM TROUGH EXTENDED FROM ALBERTA INTO THE NRN ROCKIES. LOW LEVEL NE FLOW PREVAILED BTWN SFC HIGH PRES OVER NRN ONTARIO AND LOW PRES OVER WRN PA. THIS HAS KEPT LES GOING INTO N CNTRL UPPER MI THIS AFTERNOON. THE STRONGEST BANDS WERE NOTED OVER ERN MARQUETTE COUNTY AND THROUGH KEWEENAW BAY TO NEAR LANSE. VIS AND RADAR LOOPS SUGGEST WEAK TROF HAS ALSO HELPED KEEP FOCUS OF LOW LEVEL CONV NEAR ERN MARQUETTE COUNTY. && .SHORT TERM...(TONIGHT AND SATURDAY) WITH THE PROGRESSIVE PATTERN...AN INVERTED TROUGH WILL DEVELOP OVER THE NRN PLAINS AND THE NRN ONTARIO HIGH WILL SHIFT TO THE EAST...RESULTING IN VEERING WINDS TONIGHT. THE NAM HAS HANDLED THE LOW LEVEL WIND FIELD PATTERN AFFECTING THE LES BEST. SO...EXPECT THE LES TO CONTINUE INTO N CNTRL UPPER MI THIS EVENING WITH CONTINUED NE FLOW BEFORE SHIFT TO E AND ESE WINDS LATE TONIGHT. EVEN WITH MAINLY MULTIPLE WIND PARALLEL BANDS...POTENTIAL REMAINS FOR ANOTHER 1 TO 3 INCHES OF SNOW INTO EARLY THIS EVENING...ESPECIALLY NEAR KEWEENAW BAY AND INTO THE HIGHER TERRAIN FROM NEGAUNEE TO SKANDIA. WITH THE TREND MORE TOWARD VARIABLE OR ESE WINDS LATE...LES SHOULD SHIFT TOWARD THE KEWEENAW PENINSULA. CONFIDENCE IS LOW WITH SNOW AMOUNTS FOR THIS AREA...GIVEN THE WEAK WIND FIELDS AND INCONSISTENT MODEL PERFORMANCE. LIGHT SNOW AHEAD OF THE MID/UPPER LEVEL LOW AND SFC TROUGH IS EXPECTED TO SPREAD INTO W UPPER MI DURING THE AFTERNOON WITH SNOW ACCUMULATION AMOUNTS OF AN INCH OR TWO. .LONG TERM (SATURDAY NIGHT THROUGH NEXT FRIDAY)... HEAVY SNOW POTENTIAL SAT NIGHT THROUGH SUN NIGHT IS MAIN CONCERN UPPER LOW CURRENTY OVR THE NRN US ROCKIES REGION ARRIVES OVR THE UPR GREAT LAKES LATE SATURDAY INTO SATURDAY NIGHT. TRACK OF H7-H5 LOWS ACROSS NRN WI COUPLED WITH INCREASING LOW-LEVEL CONVERGENCE FM EAST TO WEST ORIENTED SFC TROUGH FAVORS CWA FOR ACCUMULATING SNOW. THIS REALLY IS NOT IN QUESTION. SNOW AMOUNTS ARE THE MAIN ISSUE. EXPECT THE SYNOPTIC SYSTEM TO REMAIN PROGRESSIVE AS PRIMARY JET ENERGY IS SLIDING OUT AHEAD OF THE UPR LOW...KEEPING THE UPR LOW MORE OPEN...AND NOT FAVORING SIGNIFICANT DEEPENING ON THE LARGE SCALE. LOOKING AT THE SYNOPTIC SNOW ALONE...NAM/GFS FORECAST SOUNDINGS ACROSS SOUTHERN HALF OF THE CWA...IMT-ESC-ISQ...SHOW PLENTY OF MOISTURE BUT THE MAJORIFY OF THE STRONGER OMEGA/LIFT IS LOCATED ABOVE THE MAXIMUM SNOW GROWTH ZONE. SETUP FAVORS A WEALTH OF HIGHER DENSITY CRYSTALS INSTEAD OF LOW DENSITY DENDRITES. USED SNOW RATIOS FM 10-15:1. SUPPOSE THERE IS ALSO A SMALL POTENTIAL OF LK ENHANCEMENT OFF LK MICHIGAN WITH ERLY FLOW. NAM REALLY HINTED AT THIS POTENTIAL BUT THAT MODEL ALSO SHOWS INCREASING SHEAR IN THE SUB H85 LAYER...MAINLY AFTER 06Z SUNDAY. BASICALLY...DUE TO QUICK MOVEMENT OF THE SYSTEM AND LOWER SNOW RATIOS...SEEMS LIKE THIS IS ON TRACK TO BE A HIGH-END ADVY EVENT AWAY FM LAKE SUPERIOR. EVEN ADVY SNOW WILL BE WELCOME OVR THE SRN CWA GIVEN THE ONGOING DROUGHT PLAUGING THAT AREA. ONE THING TO WATCH THOUGH. 12Z NAM AND 12Z ECMWF SHOW A SLOWER MOVEMENT TO THE UPR LEVEL TROUGH/SFC TROUGH...RESULTING IN A LONGER DURATION OF SNOW. IF THESE FEATURES HANG UP MORE...THEN THERE WOULD NEED TO BE AN INCREASE OF SNOW FOR THE SERN/ERN CWA. AS ALLUDED TO BEFORE...DUE TO EXPECTED PROGRESSIVE NATURE OF THE SYSTEM...FAVORED QUICKER SOLUTION AND NOT AS MUCH SNOW MAIN IMPACT FM SYSTEM AT THIS TIME LOOKS TO BE THE INCREASING LAKE ENHANCEMENT FOR WRN CWA SATURDAY NIGHT AND THE NCNTRL SUNDAY INTO SUNDAY NIGHT. LEADING OFF...ERLY LOW-LEVEL WINDS WITH H85 TEMPS AROUND -15C SATURDAY NIGHT TARGET THE KEWEENAW PENINSULA FOR THE HEAVIEST SNOW. UNLIKE THE SRN CWA...SOUNDINGS OVR THE KEWEENAW ALSO INDICATE MOST OF THE LIFT OCCURRING IN THE BEST SNOW GROWTH ZONE. H95 CONVERGENCE INCREASES SATURDAY EVENING AND PERISTS INTO SUNDAY MORNING. LATER SUNDAY MORNING INTO SUNDAY AFTERNOON...SFC-H85 WINDS BACK MORE NRLY WHICH BRINGS FAR WRN CWA AND NCNTRL CWA INTO FOLD FOR HEAVIER LK EFFECT. SOUNDINGS QUITE FAVORABLE WITH DEEP MOISTURE THROUGH 20KFT AND STRONG OMEGA/LIFT RIGHT WITHIN THE SNOW GROWTH ZONE. CROSSHAIR SIGNATURE SHOWS UP NICELY ON THE MQT SOUDNINGS... SUGGESTING INTENSE SNOW RATES AND HIGH SNOW RATIOS...PROBABLY SURGING TOWARD 30:1 BY SUNDAY AFTN. MAIN NEGATIVE FOR SIGNIFICANT ACCUMS DURING THE PERIOD WILL BE FRATURING OF SNOWFLAKES AS WINDS IN THE MIXED LAYER ARE INCREASING TO 25-35 KNOTS. STILL...UPSLOPE AREAS OF WRN AND NCNTRL CWA SHOULD DO WELL WITH 350-010 WIND DIRECTION. POTENTIAL FOR HEAVIER LK EFFECT SNOW AND STRONG WINDS/BLSN JUSTIFIES WINTER STORM WATCH FOR GOGEBIC THROUGH KEWEENAW AND FOR MARQUETTE COUNTY. SNOW AMOUNTS AWAY FM THESE AREAS SHOULD REMAIN BLO WARNING CRITERIA AND ANTICIPATE ADVY NEEDED ACROSS REST OF THE CWA. IF THE UPR LOW SLOWS DOWN THOUGH...WE WOULD NEED WATCHES FOR MUCH OF THE SOUTH AND ERN CWA. EXPECT LINGERING LK EFFECT THROUGH MONDAY BUT LOW-LEVEL WINDS WILL STEADILY BACK SW...ALLOWING HEAVIER SNOW TO BECOME MORE TRANSIENT. BY LATE AFTN...EXPECT MOST OF THE SNOW TO RESIDE OVR THE KEWEENAW PENINSULA. WRLY FLOW LK EFFECT SHOULD CONTINUE INTO MON NIGHT OVR THE KEWEENAW. THOUGH...INCREASING LOW-LEVEL SHEAR AND DECREASING MOISTURE WILL BE NEGATIVE FACTORS. LOW PRESSURE TROUGH EJECTING INTO THE CENTRAL PLAINS LIFTS ACROSS GREAT LAKES TUESDAY/TUESDAY NIGHT. HPC PREFEREED THE WEAKER/SLOWER GFS AS THE ECMWF WAS A STRONGER AND PROGRESSIVE OUTLIER. NUDGED POPS UPWARD EAST DUE TO BETTER MOISTURE TRANSPORT INTO THE SYSTEM AND POTENTIAL FOR SOME ENHANCEMENT OFF LK MICHIGAN. CYCLONIC FLOW/LK EFFECT CONTINUES IN THE WAKE OF THE THE TUESDAY LOW PRESSURE TROUGH...ESPECIALLY IN THE AREAS ALONG LK SUPERIOR FAVORED BY NW LOW-LEVEL FLOW. INTERESTING THAT NOW THE 12Z GFS AND ECMWF POINT TO ANOTHER WAVE OF LOW PRESSURE WITH MORE SYSTEM SNOW NEXT WEDNESDAY. WOULD STILL EXPECT THE HIGHEST POPS CLOSER TO LAKE SUPERIOR WITH ADDED BENEFIT FM ONSHORE FLOW. HIGH PRESSURE RIDGE THEN CROSSES THE UPR GREAT LAKES ON CHRISTMAS DAY. OTHER THAN LINGERING LK EFFECT FOR W/SW FLOW AREAS EARLY ON...SHOULD SEE TRANQUIL WEATHER. QUIET WEATHER WILL NOT LAST THOUGH. BY FRIDAY...UPPER TROUGH DEEPENS OVR WRN CONUS WHILE RIDGE POPS UP OVR ERN UNITED STATES. SWRLY FLOW ALOFT BRINGS ANOTHER LOW PRESSURE INTO THE GREAT LAKES. DECENT AGREEMENT FM GFS/ECMWF/CANADIAN THAT A WOUND UP SFC LOW WILL LIFT TOWARD UPR MI FRI/SAT. IF THIS OCCURS...WOULD HAVE MIXED PCPN CONCERNS AS WARMER AIR STREAMS INTO ERN HALF OF UPR MI. DID NOT WANT TO JUMP ON THE POTENTIAL FOR RAIN QUITE YET AS A COUPLE PREVIOUS LOW PRESSURE SYSTEMS THIS MONTH WERE FORECAST TO TRACK FARTHER NORTH THAN ENDED UP HAPPENING. NO MATTER WHAT... PATTERN STAYS ACTIVE WITH WRN TROUGH/ERN RIDGE PERSISTING AND SIGNIFICANT LOW PRESSURE SYSTEMS AFFECTING THE REGION INTO THE FINAL WEEK OF 2008. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... EXPECT IFR CONDITIONS AT SAW TO TREND TOWARD VFR BY LATE EVNG WITH FCST WEAKENING/VEERING WINDS TO MORE E CAUSING LES TO FOCUS CLOSER TO THE LK SUP SHORE. MVFR CIGS ARE LIKELY TO RETURN ON SAT AFTN WITH UPSLOPE SE FLOW OFF LK MI. UNFAVORABLE NE FLOW AT CMX THIS EVNG WL TEND TO VEER MORE E OVERNGT...SO EXPECT SOME LES TO DVLP LATER. BUT DVLPMNT OF VORTEX NEAR MQT WL LIKELY DISRUPT THIS FLOW/INCRS SHEAR AND LES INTENSITY. OVERALL...PLAN ON PREDOMINANT MVFR CIGS OVERNGT WITH LOWER MVFR VSBYS LIKELY AFT 06Z. ON SAT...HIER RES MODELS SHOW VORTEX WEAKENING WITH A PD OF UNIDIRECTIONAL ESE SFC-H925 FLOW CAUSING A BETTER CHC OF LES AND IFR VSBYS. AS THIS FLOW VEERS MORE SE LATER IN THE DAY WITH SHORTER OVERWATER FETCH/DOWNSLOPE OFF HURON MTNS...SUSPECT LES INTENSITY WL DIMINISH A BIT. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... AS LOW PRESSURE OVER WESTERN PA MOVES OFF THE EAST COAST THIS EVENING...NE WINDS WILL CONTINUE TO DIMINISH. NRLY GALE FORCE WINDS ARE EXPECTED SUNDAY AS A LOW PRESSURE TROUGH OVER MINNESOTA SATURDAY EVENING CONSOLIDATES INTO A LOW PRESSURE AREA AND DEEPENS AS IT CROSSES LOWER MICHIGAN. IN ADDITION TO THE GALES FROM THE LOW PRESSURE SYSTEM...HEAVY FREEZING SPRAY IS LIKELY AS COLD AIR IS DRAWN SOUTH OUT OF CENTRAL CANADA. LOOK FOR THE HEAVY FREEZING SPRAY AND WINDS TO DIMINISH SUNDAY NIGHT AND BACK WESTERLY FOR MONDAY...BUT WIND SPEEDS WILL STILL REMAIN BETWEEN 15 AND 30 KNOTS. NO OTHER GALES ARE EXPECTED DURING THE REST OF THE FORECAST PERIOD. && UPPER MICHIGAN... LAKE EFFECT SNOW WARNING UNTIL 11 PM EST THIS EVENING FOR MIZ006. WINTER STORM WATCH FROM SATURDAY EVENING THROUGH LATE SUNDAY NIGHT FOR MIZ001-003. LAKE EFFECT SNOW ADVISORY UNTIL 1 AM EST SATURDAY FOR MIZ004. WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH MONDAY MORNING FOR MIZ002-009. LAKE EFFECT SNOW WARNING UNTIL 5 AM EST SATURDAY FOR MIZ005. WINTER STORM WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY MORNING FOR MIZ005. LAKE SUPERIOR... GALE WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY MORNING FOR LSZ264-266. GALE WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR LSZ162- 263. LAKE MICHIGAN...NONE. && $$ UPDATE...KC SYNOPSIS...JLB SHORT TERM...JLB LONG TERM...JLA AVIATION...KC MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 405 PM EST FRI DEC 19 2008 .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED THAT THE VIGOROUS SHORTWAVE TROUGH THAT BROUGHT HEAVY SNOW TO WI/MI WAS QUICKLY MOVING EASTWARD THROUGH THE ERN GREAT LAKES. THE NEXT SIGNIFICANT MID/UPPER LEVEL UPSTREAM TROUGH EXTENDED FROM ALBERTA INTO THE NRN ROCKIES. LOW LEVEL NE FLOW PREVAILED BTWN SFC HIGH PRES OVER NRN ONTARIO AND LOW PRES OVER WRN PA. THIS HAS KEPT LES GOING INTO N CNTRL UPPER MI THIS AFTERNOON. THE STRONGEST BANDS WERE NOTED OVER ERN MARQUETTE COUNTY AND THROUGH KEWEENAW BAY TO NEAR LANSE. VIS AND RADAR LOOPS SUGGEST WEAK TROF HAS ALSO HELPED KEEP FOCUS OF LOW LEVEL CONV NEAR ERN MARQUETTE COUNTY. && .SHORT TERM...(TONIGHT AND SATURDAY) WITH THE PROGRESSIVE PATTERN...AN INVERTED TROUGH WILL DEVELOP OVER THE NRN PLAINS AND THE NRN ONTARIO HIGH WILL SHIFT TO THE EAST...RESULTING IN VEERING WINDS TONIGHT. THE NAM HAS HANDLED THE LOW LEVEL WIND FIELD PATTERN AFFECTING THE LES BEST. SO...EXPECT THE LES TO CONTINUE INTO N CNTRL UPPER MI THIS EVENING WITH CONTINUED NE FLOW BEFORE SHIFT TO E AND ESE WINDS LATE TONIGHT. EVEN WITH MAINLY MULTIPLE WIND PARALLEL BANDS...POTENTIAL REMAINS FOR ANOTHER 1 TO 3 INCHES OF SNOW INTO EARLY THIS EVENING...ESPECIALLY NEAR KEWEENAW BAY AND INTO THE HIGHER TERRAIN FROM NEGAUNEE TO SKANDIA. WITH THE TREND MORE TOWARD VARIABLE OR ESE WINDS LATE...LES SHOULD SHIFT TOWARD THE KEWEENAW PENINSULA. CONFIDENCE IS LOW WITH SNOW AMOUNTS FOR THIS AREA...GIVEN THE WEAK WIND FIELDS AND INCONSISTENT MODEL PERFORMANCE. LIGHT SNOW AHEAD OF THE MID/UPPER LEVEL LOW AND SFC TROUGH IS EXPECTED TO SPREAD INTO W UPPER MI DURING THE AFTERNOON WITH SNOW ACCUMULATION AMOUNTS OF AN INCH OR TWO. .LONG TERM (SATURDAY NIGHT THROUGH NEXT FRIDAY)... HEAVY SNOW POTENTIAL SAT NIGHT THROUGH SUN NIGHT IS MAIN CONCERN UPPER LOW CURRENTY OVR THE NRN US ROCKIES REGION ARRIVES OVR THE UPR GREAT LAKES LATE SATURDAY INTO SATURDAY NIGHT. TRACK OF H7-H5 LOWS ACROSS NRN WI COUPLED WITH INCREASING LOW-LEVEL CONVERGENCE FM EAST TO WEST ORIENTED SFC TROUGH FAVORS CWA FOR ACCUMULATING SNOW. THIS REALLY IS NOT IN QUESTION. SNOW AMOUNTS ARE THE MAIN ISSUE. EXPECT THE SYNOPTIC SYSTEM TO REMAIN PROGRESSIVE AS PRIMARY JET ENERGY IS SLIDING OUT AHEAD OF THE UPR LOW...KEEPING THE UPR LOW MORE OPEN...AND NOT FAVORING SIGNIFICANT DEEPENING ON THE LARGE SCALE. LOOKING AT THE SYNOPTIC SNOW ALONE...NAM/GFS FORECAST SOUNDINGS ACROSS SOUTHERN HALF OF THE CWA...IMT-ESC-ISQ...SHOW PLENTY OF MOISTURE BUT THE MAJORIFY OF THE STRONGER OMEGA/LIFT IS LOCATED ABOVE THE MAXIMUM SNOW GROWTH ZONE. SETUP FAVORS A WEALTH OF HIGHER DENSITY CRYSTALS INSTEAD OF LOW DENSITY DENDRITES. USED SNOW RATIOS FM 10-15:1. SUPPOSE THERE IS ALSO A SMALL POTENTIAL OF LK ENHANCEMENT OFF LK MICHIGAN WITH ERLY FLOW. NAM REALLY HINTED AT THIS POTENTIAL BUT THAT MODEL ALSO SHOWS INCREASING SHEAR IN THE SUB H85 LAYER...MAINLY AFTER 06Z SUNDAY. BASICALLY...DUE TO QUICK MOVEMENT OF THE SYSTEM AND LOWER SNOW RATIOS...SEEMS LIKE THIS IS ON TRACK TO BE A HIGH-END ADVY EVENT AWAY FM LAKE SUPERIOR. EVEN ADVY SNOW WILL BE WELCOME OVR THE SRN CWA GIVEN THE ONGOING DROUGHT PLAUGING THAT AREA. ONE THING TO WATCH THOUGH. 12Z NAM AND 12Z ECMWF SHOW A SLOWER MOVEMENT TO THE UPR LEVEL TROUGH/SFC TROUGH...RESULTING IN A LONGER DURATION OF SNOW. IF THESE FEATURES HANG UP MORE...THEN THERE WOULD NEED TO BE AN INCREASE OF SNOW FOR THE SERN/ERN CWA. AS ALLUDED TO BEFORE...DUE TO EXPECTED PROGRESSIVE NATURE OF THE SYSTEM...FAVORED QUICKER SOLUTION AND NOT AS MUCH SNOW MAIN IMPACT FM SYSTEM AT THIS TIME LOOKS TO BE THE INCREASING LAKE ENHANCEMENT FOR WRN CWA SATURDAY NIGHT AND THE NCNTRL SUNDAY INTO SUNDAY NIGHT. LEADING OFF...ERLY LOW-LEVEL WINDS WITH H85 TEMPS AROUND -15C SATURDAY NIGHT TARGET THE KEWEENAW PENINSULA FOR THE HEAVIEST SNOW. UNLIKE THE SRN CWA...SOUNDINGS OVR THE KEWEENAW ALSO INDICATE MOST OF THE LIFT OCCURRING IN THE BEST SNOW GROWTH ZONE. H95 CONVERGENCE INCREASES SATURDAY EVENING AND PERISTS INTO SUNDAY MORNING. LATER SUNDAY MORNING INTO SUNDAY AFTERNOON...SFC-H85 WINDS BACK MORE NRLY WHICH BRINGS FAR WRN CWA AND NCNTRL CWA INTO FOLD FOR HEAVIER LK EFFECT. SOUNDINGS QUITE FAVORABLE WITH DEEP MOISTURE THROUGH 20KFT AND STRONG OMEGA/LIFT RIGHT WITHIN THE SNOW GROWTH ZONE. CROSSHAIR SIGNATURE SHOWS UP NICELY ON THE MQT SOUDNINGS... SUGGESTING INTENSE SNOW RATES AND HIGH SNOW RATIOS...PROBABLY SURGING TOWARD 30:1 BY SUNDAY AFTN. MAIN NEGATIVE FOR SIGNIFICANT ACCUMS DURING THE PERIOD WILL BE FRATURING OF SNOWFLAKES AS WINDS IN THE MIXED LAYER ARE INCREASING TO 25-35 KNOTS. STILL...UPSLOPE AREAS OF WRN AND NCNTRL CWA SHOULD DO WELL WITH 350-010 WIND DIRECTION. POTENTIAL FOR HEAVIER LK EFFECT SNOW AND STRONG WINDS/BLSN JUSTIFIES WINTER STORM WATCH FOR GOGEBIC THROUGH KEWEENAW AND FOR MARQUETTE COUNTY. SNOW AMOUNTS AWAY FM THESE AREAS SHOULD REMAIN BLO WARNING CRITERIA AND ANTICIPATE ADVY NEEDED ACROSS REST OF THE CWA. IF THE UPR LOW SLOWS DOWN THOUGH...WE WOULD NEED WATCHES FOR MUCH OF THE SOUTH AND ERN CWA. EXPECT LINGERING LK EFFECT THROUGH MONDAY BUT LOW-LEVEL WINDS WILL STEADILY BACK SW...ALLOWING HEAVIER SNOW TO BECOME MORE TRANSIENT. BY LATE AFTN...EXPECT MOST OF THE SNOW TO RESIDE OVR THE KEWEENAW PENINSULA. WRLY FLOW LK EFFECT SHOULD CONTINUE INTO MON NIGHT OVR THE KEWEENAW. THOUGH...INCREASING LOW-LEVEL SHEAR AND DECREASING MOISTURE WILL BE NEGATIVE FACTORS. LOW PRESSURE TROUGH EJECTING INTO THE CENTRAL PLAINS LIFTS ACROSS GREAT LAKES TUESDAY/TUESDAY NIGHT. HPC PREFEREED THE WEAKER/SLOWER GFS AS THE ECMWF WAS A STRONGER AND PROGRESSIVE OUTLIER. NUDGED POPS UPWARD EAST DUE TO BETTER MOISTURE TRANSPORT INTO THE SYSTEM AND POTENTIAL FOR SOME ENHANCEMENT OFF LK MICHIGAN. CYCLONIC FLOW/LK EFFECT CONTINUES IN THE WAKE OF THE THE TUESDAY LOW PRESSURE TROUGH...ESPECIALLY IN THE AREAS ALONG LK SUPERIOR FAVORED BY NW LOW-LEVEL FLOW. INTERESTING THAT NOW THE 12Z GFS AND ECMWF POINT TO ANOTHER WAVE OF LOW PRESSURE WITH MORE SYSTEM SNOW NEXT WEDNESDAY. WOULD STILL EXPECT THE HIGHEST POPS CLOSER TO LAKE SUPERIOR WITH ADDED BENEFIT FM ONSHORE FLOW. HIGH PRESSURE RIDGE THEN CROSSES THE UPR GREAT LAKES ON CHRISTMAS DAY. OTHER THAN LINGERING LK EFFECT FOR W/SW FLOW AREAS EARLY ON...SHOULD SEE TRANQUIL WEATHER. QUIET WEATHER WILL NOT LAST THOUGH. BY FRIDAY...UPPER TROUGH DEEPENS OVR WRN CONUS WHILE RIDGE POPS UP OVR ERN UNITED STATES. SWRLY FLOW ALOFT BRINGS ANOTHER LOW PRESSURE INTO THE GREAT LAKES. DECENT AGREEMENT FM GFS/ECMWF/CANADIAN THAT A WOUND UP SFC LOW WILL LIFT TOWARD UPR MI FRI/SAT. IF THIS OCCURS... WOULD HAVE MIXED PCPN CONCERNS AS WARMER AIR STREAMS INTO ERN HALF OF UPR MI. DID NOT WANT TO JUMP ON THE POTENTIAL FOR RAIN QUITE YET AS A COUPLE PREVIOUS LOW PRESSURE SYSTEMS THIS MONTH WERE FORECAST TO TRACK FARTHER NORTH THAN ENDED UP HAPPENING. NO MATTER WHAT... PATTERN STAYS ACTIVE WITH WRN TROUGH/ERN RIDGE PERSISTING AND SIGNIFICANT LOW PRESSURE SYSTEMS AFFECTING THE REGION INTO THE FINAL WEEK OF 2008. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... ALTHOUGH MOST OF THE LES WILL REMAIN TO THE NORTH...ENE FLOW WILL BRING OCNL LAKE EFFECT SNOW SHOWERS INTO KSAW. WINDS TURN SOUTHEAST AFTER MIDNIGHT TONIGHT ABOVE THE SURFACE...WHICH SHOULD HELP END THE LAKE EFFECT SNOW AND ALLOW CONDITIONS TO GO TO VFR. AT KCMX...NORTHEAST FLOW LOOKS TO CONTINUE THROUGH AT LEAST THE NEXT 18 HOURS...WHICH IS NOT FAVORABLE FOR LES THERE. AFTER 06Z TONIGHT AS THE WINDS TURN EAST AND EVENTUALLY SE...THE BAND THAT IS CURRENTLY AFFECTING MARQUETTE COUNTY SHOULD IMPACT CMX...BRINGING VSBYS DOWN TO AT LEAST IFR. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... AS LOW PRESSURE OVER WESTERN PA MOVES OFF THE EAST COAST THIS EVENING...NE WINDS WILL CONTINUE TO DIMINISH. NRLY GALE FORCE WINDS ARE EXPECTED SUNDAY AS A LOW PRESSURE TROUGH OVER MINNESOTA SATURDAY EVENING CONSOLIDATES INTO A LOW PRESSURE AREA AND DEEPENS AS IT CROSSES LOWER MICHIGAN. IN ADDITION TO THE GALES FROM THE LOW PRESSURE SYSTEM...HEAVY FREEZING SPRAY IS LIKELY AS COLD AIR IS DRAWN SOUTH OUT OF CENTRAL CANADA. LOOK FOR THE HEAVY FREEZING SPRAY AND WINDS TO DIMINISH SUNDAY NIGHT AND BACK WESTERLY FOR MONDAY...BUT WIND SPEEDS WILL STILL REMAIN BETWEEN 15 AND 30 KNOTS. NO OTHER GALES ARE EXPECTED DURING THE REST OF THE FORECAST PERIOD. && UPPER MICHIGAN... WINTER STORM WATCH FROM SATURDAY EVENING THROUGH LATE SUNDAY NIGHT FOR MIZ001-003. LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ004. WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH MONDAY MORNING FOR MIZ002-009. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ005. WINTER STORM WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY MORNING FOR MIZ005. LAKE SUPERIOR... GALE WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY MORNING FOR LSZ264-266. GALE WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR LSZ162- 263. LAKE MICHIGAN...NONE. && $$ SYNOPSIS...JLB SHORT TERM...JLB LONG TERM...JLA AVIATION...JLB MARINE...JLB mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1230 AM EST FRI DEC 19 2008 UPDATED FOR 06Z TAF ISSUANCE .UPDATE... BASED ON SPOTTER REPORTS OF PERSISTENT HEAVIER SHSN OVER NRN KEWEENAW COUNTY EARLY THIS EVNG WITH REPORTS OF AS MUCH AS AN INCH/HR...POSTED AN LES ADVY FOR THAT AREA...BUT ONLY THRU MIDNGT AS OBSVD NE FLOW S OF BLDG HI PRES IN SRN ONTARIO AND N OF SWD MOVING LO PRES TROF IS NOT FVRBL FOR PERSISTENT HEAVIER LES. ALSO OPTED TO EXTEND GOING LES ADVY FOR NRN CMX COUNTY AND ADD AN ADVY FOR NRN BARAGA/MQT COUNTIES THRU THE DAY ON FRI WITH DVLPG LLVL ENE FLOW IN THE WAKE OF TROF PASSAGE TO THE S. LATEST 88D RADAR SHOWS BAND OF SHSN ALG LO PRES TROF APRCHG NRN MQT COUNTY WITH SOME REFLECTIVITIES AOA 30 DBZ. WITH PERSISTENT ENE H925 FLOW THRU FRI AS SHOWN BY 18Z GFS AS WELL AS LO H85 TEMPS ARND -15C MAINTAINING FVRBL OVERWATER INSTABILITY...SETUP SEEMS GOOD FOR LES FM S OF CMX AT THE END OF FETCH IN KEWEENAW BAY TO THE HURON MTNS AND NRN MQT COUNTY. FVRBL THERMAL PROFILE FOR DENDRITIC SN GROWTH/LLVL MSTR SHOWN ON 20Z TAMDAR SDNG FM CMX AND PERSISTENT UPSLOPE ENE FLOW IN THE WAKE OF LO PRES TROF PASSAGE/LLVL CNVGC INCRSD CONFIDENCE THERE WL BE SOME ADVY SN AMTS IN THIS AREA BTWN CMX AND BARAGA AS WELL AS THE HURON MTNS AND ISHPEMING/NEGAUNEE. WITH CLR SKIES...TEMPS ALSO NOSEDIVED FASTER THAN PREVIOUS FCST OVER THE INTERIOR. SO LOWERED GOING FCST MINS TO REFLECT SUBSTANTIAL RADIATIONAL HEAT LOSS WITH LGT WINDS. ARRIVAL OF MID/HI CLD SHOWN SWEEPING NEWD ON STLT IMAGERY AS WELL AS WSHFT TO MORE NE IN THE WAKE OF LO PRES TROF PASAGE AND OFF THE MODERATING INFLUENCE OF LK SUP WL CAUSE EARLY LO TEMPS TO RISE THRU THE NGT. && .SYNOPSIS...WV IMAGERY AND RUC ANALYSIS INDICATED WRLY MID/UPPER LEVEL NRN STREAM FLOW THROUGH THE UPPER GREAT LAKES ON THE REAR FLANK OF A MID LEVEL LOW OVER ERN CANADA. A SHEARED SHRTWV TROF VCNTY CYQT WAS MOVING QUICKLY EASTWARD WHILE A STRONG SRN STREAM SHRTWV WA LIFTING NE FROM CO. AT THE SFC...A WEST TO EAST TROUGH EXTENDED THROUGH THE NRN KEWEENAW PENINSULA AND CNTRL LAKE SUPERIOR. STRONG CONVERGENCE ALONG THIS FEATURE WHICH SUPPORTED A BAND OF HEAVY LAKE EFFECT SNOW WAS GRADUALLY SHIFTING TO THE SOUTH AS HIGH PRES STRENGTHENS BEHIND THE ONTARIO SHRTWV. .SHORT TERM...(TONIGHT AND FRIDAY) EXPECT THE LES BAND TO CONTINUE TO SHIFT TO THE SOUTH THIS EVENING THROUGH KCMX AND HOUGHTON WITH BRIEF PERIOD OF HEAVIER SNOWFALL. SNOWFALL RATES WILL DROP OFF QUICKLY ONCE MULTIBAND LES DEVELOPS IN THE WAKE OF THE TROUGH. UNCERTAINTY REMAINS HOWEVER ON HOW FAR AND HOW QUICKLY THE TROUGH WILL MOVE LATE THIS EVENING AND OVERNIGHT. THE 12Z/18Z LCL HIGH RES WRF/ARW SUGGESTS A STRONG ENOUGH LAND BREEZE WILL KEEP THE BAND MAINLY ALONG OR NORTH OF M-28 WHILE THE 12Z/18Z NAM ALLOWS NE FLOW TO PENETRATE FARTHER INLAND. FCST LEANS MORE TOWARD THE LCL WRF/ARW BUT STILL KEEPS POTENTIAL FOR A FEW INCHES OF ACCUMULATION VCNTY MARQUETTE. THE NAM AND GFS WERE IN DECENT AGREEMENT WITH PCPN AMOUNTS/COVERAGE TO THE NORTH OF THE VIGOROUS SHRTWV AND SFC LOW MOVING TOWARD THE SRN GREAT LAKES. SNOW WILL BE LIKELY SOUTH OF US-2 WITH POTENTIAL SNOWFALL AMOUNTS TO AROUND 3 INCHES OVER THE FAR SOUTHERN CWA VCNTY KMNM LATE TONIGHT INTO FRI MORNING. OTHERWISE...ONLY A CHANCE OF LIGHT SNOW IS EXPECTED FARTHER NORTH. .LONG TERM... THE MID LEVEL CLOSED LOW OVER SOUTHERN ALBERTA WILL DIP INTO NORTHEAST MONTANA FRIDAY NIGHT AS A RIDGE ADVANCING OUT OF THE SOUTH CENTRAL CANADA INTO ONTARIO. A WEAK SHORTWAVE AND INCREASE Q-VECTOR CONVERGENCE WILL SHIFT ACROSS THE FORECAST AREA. SURFACE ANALYSIS DEPICTS A NEARLY STATIONARY RIDGE STRETCHING FROM CENTRAL MANITOBA...ACROSS NORTHERN ONTARIO INTO SOUTHERN QUEBEC. A SURFACE LOW WILL MOVE OUT OF THE MIDDLE HIGH PLAINS INTO SOUTHWEST MINNESOTA. 290K ISENTROPIC ANALYSIS DEPICTS WEAK ASCENT AHEAD OF THE LOW. LAKE SUPERIOR-850MB DELTA-T`S WILL AROUND 22C...INDICATIVE OF LOW LEVEL INSTABILITY. THUS WILL KEEP LES GOING MAINLY FOR THE KEWEENAW PENINSULA. THE MID LEVEL LOW WILL TRACK INTO EASTERN DAKOTAS ON SATURDAY. A WEAK SHORTWAVE EJECTED OUT AHEAD OF THE LOW WILL SHIFT ACROSS THE FORECAST AREA. THE SURFACE RIDGE REMAINS OVER NORTHERN ONTARIO...THE SURFACE LOW WILL MOVE INTO THE MSP AREA AND WEAKENS WHILE STARTING TO MERGE WITH A STRONGER LOW OVER THE MIDDLE MISSISSIPPI RIVER VALLEY. ISENTROPIC ASCENT AHEAD OF THIS LOW WILL INCREASE THE POTENTIAL FOR SNOW MAINLY OVER THE WESTERN U.P. COOL 850MB TEMPERATURES OF AROUND -12C WILL CONTRIBUTE TO CONTINUED UNSEASONABLY COLD TEMPERATURES OVER THE AREA. THE MID LEVEL LOW WILL SWING INTO SOUTHERN LAKE MICHIGAN SATURDAY NIGHT. WEAK SHORTWAVES AND LOW LEVEL DEEP MOISTURE WILL PRODUCE SNOWS OVER THE AREA...MAINLY THE SOUTHERN PART CLOSER TO THE LOW. THE SURFACE LOWS WILL MERGE AND LIFT NORTHEAST INTO THE LOWER GREAT LAKES. A SURFACE TROUGH...WHICH IS THE RESIDUE OF THE MERGER OF THE LOWS...WILL EXTEND WEST THROUGH CENTRAL WISCONSIN AND REMAIN SOUTH OF THE FORECAST AREA. THIS WILL CAUSE AN EASTERLY WIND ACROSS LAKE SUPERIOR...WHICH SHOULD CAUSE SOME LES ENHANCEMENT MAINLY OVER THE KEWEENAW PENINSULA. THE MID LEVEL LOW WILL TRACK INTO THE LOWER GREAT LAKES ON SUNDAY...WHILE THE SURFACE SLOWS AND MOVES TO SOUTHWEST QUEBEC AND SOUTHERN NEW ENGLAND AREAS. A RIDGE OF HIGH PRESSURE WILL BUILD OVER THE CENTRAL AND NORTHERN PLAINS. AS THE HIGH APPROACHES AND THE LOW MOVES EAST. THE SURFACE WINDS WILL BACK TO THE NORTH. THE COLD TEMPERATURES OVER THE LAKE AND WINDS BACKING NORTH WILL CAUSE LES TO DEVELOP OVER THE CENTRAL U.P. THE MID RANGE MODELS AGREE FAIRLY WELL. HPC RECOMMENDS A BLEND OF 00Z ECMWF/00Z GFS. THIS APPEARS TO BE CLOSE TO THE CANADIAN GLOBAL AT LEAST THROUGH DAY 6. THUS PLAN TO STAY CLOSER TO THE GLOBAL AND/OR A BLEND OF GFS/ECMWF. THE MID LEVEL LOW OVER THE LOWER GREAT LAKES WILL LIFT NORTHEAST INTO NEW ENGLAND BY SUNDAY NIGHT WHILE A RIDGE BUILDS OVER THE NORTHERN PLAINS. A WEAK SHORTWAVE WILL SWEEP ACROSS THE FORECAST AREA. THE SURFACE HIGH WILL SHIFT OVER THE OZARK MOUNTAINS. THIS WILL CAUSE THE WINDS TO BE MAINLY OUT OF THE NORTH BACKING TO THE NORTHWEST. LAKE-850MB DELTA-T`S SHOULD REMAIN AROUND 24C OVER LAKE SUPERIOR. CONDITIONS LOOK FAVORABLE FOR A CHANCE OF SNOW WITH SOME LES ENHANCEMENT...MAINLY OVER THE WEST...IN PARTICULAR THE KEWEENAW PENINUSLA. THE SHORTWAVE WILL RELOCATE EAST OF THE U.P. ON MONDAY. THE BROAD SURFACE HIGH WILL SHIFT OVER MUCH OF SOUTHEAST CONUS. THIS WILL CAUSE THE WINDS TO CONTINUE TO BACK WEST. THE DELTA-T`S WILL REMAIN AROUND 20C. CONDITIONS SUPPORT KEEPING THE SOME LES GOING MAINLY OVER THE NORTHERN U.P. DRIER CONDITIONS,,,LOSS OF THE UPPER LEVEL SUPPORT AND WINDS BACKING WEST WILL REDUCED SNOWFALL. THE WEAK MID LEVEL RIDGE WILL SHIFT ACROSS THE FORECAST AREA MONDAY NIGHT. THE SURFACE HIGH WILL TRACK EAST INTO THE MID ATLANTIC STATES...WHILE A LOW DEEPENS OVER THE CENTRAL PLAINS. TOGETHER THESE SHOULD CAUSE WINDS TO BACK TO THE SOUTH. DELTA-T`S WILL BE AROUND 18C OVER LAKE MICHIGAN. A SOUTHERLY WINDS WILL BRING LES TO THE SOUTHERN U.P. MAINLY LATE MONDAY NIGHT. THERE IS STILL ENOUGH LOW LEVEL INSTABILITY TO SUPPORT A SLIGHT CHANCE OF SNOW ELSEWHERE MONDAY NIGHT. A LONGWAVE TROUGH WILL DEEPEN OVER THE SOUTH CENTRAL CANADA AND THE NORTHERN PLAINS ON TUESDAY PUSHING TWO WEAK SHORTWAVES THROUGH THE FORECAST AREA. A SURFACE RIDGE WILL SETTLE OVER THE NORTHERN PLAINS PUSHING A COLD FRONT THROUGH THE FORECAST AREA. THE FRONTAL SYSTEM AND SHORTWAVE ENERGY WILL PRODUCE A CHANCE OF SNOW SHOWERS ACROSS THE AREA. THE HIGH WILL SETTLE INTO THE MIDDLE MISSISSIPPI RIVER VALLEY ON WEDNESDAY CAUSING THE WINDS TO BACK TO THE WEST. THIS WILL DELTA-T`S OF AROUND 20C WILL LIKELY PRODUCE SOME LAKE EFFECT SNOWS AGAIN. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... AT KSAW...EXPECT VFR CONDITIONS EARLY THIS MRNG TO GIVE WAY TO AN IFR VSBY/MVFR CIG AT TIMES FOR THE NEXT COUPLE OF HRS AS LES BAND OVER NRN MQT COUNTY SINKS TO THE S. HOWEVER...SUSPECT DENSE COLD AIR OVER THE INTERIOR WL HOLD UP THE SWD PROGRESS OF THIS BAND...SO LOWER CONDITIONS WL LIKELY BE ONLY INTERMITTENT. AS LARGER SCALE LLVL FLOW TENDS TO BACK A BIT MORE NE THIS AFTN/EVNG...THINK PREDOMINANT MVFR CONDITIONS WL DVLP IN THE AFTN AND PERSIST THRU THE END OF THE FCST PD. AT KCMX...CURRENT UNFVRBL NE WIND WL LIKELY MAINTAIN PREDOMINANT VFR CONDITIONS FOR THE NEXT COUPLE OF HRS. HOWEVER...NUMERICAL MODELS SHOW BACKING LLVL FLOW AFT ABOUT 09Z OR SO. WITH MORE OF AN ELY COMPONENT...LES AND LOWER VSBY/CIGS WL LIKELY MIGRATE BACK INTO CMX. BUT CONDITIONS SHOULD THEN SWITCH BACK TO VFR WITH BACKING LLVL FLOW TO MORE NE ON FRI. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRES WILL STRENGTHEN OVER NORTHERN ONTARIO TONIGHT AS LOW PRESSURE DEEPENS FORMS OVR THE CNTRL PLAINS AND MOVES INTO THE OHIO VALLEY BY FRI. THE TIGHT PRESSURE GRADIENT BTWN THE TWO SYSTEMS SHOULD RESULT IN GALE FORCE WINDS OVR WRN LAKE SUPERIOR LATE TONIGHT NIGHT INTO FRIDAY. AFTER A LULL IN WINDS FRIDAY NIGHT INTO SATURDAY...NORTHEAST TO NORTH GALES ARE POSSIBLE OVR MUCH OF THE LAKE LATE SATURDAY NIGHT THROUGH SUNDAY NIGHT AS A STRONG LOW LIFTS INTO THE CENTRAL AND EASTERN GREAT LAKES. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST FRIDAY FOR MIZ004-005. LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST FRIDAY FOR MIZ003. LAKE EFFECT SNOW ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MIZ001. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING FROM 3 AM EST /2 AM CST/ TO 1 PM EST /12 PM CST/ FRIDAY FOR LSZ162-263. GALE WARNING FROM 3 AM EST /2 AM CST/ TO 1 PM EST /12 PM CST/ FRIDAY FOR LSZ162-263. LAKE MICHIGAN...NONE. && $$ UPDATE...KC SYNOPSIS/SHORT TERM...JLB LONG TERM...DLG AVIATION...KC MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1204 PM CST FRI DEC 19 2008 .UPDATE... ADDED AVIATION DISCUSSION FOR 18Z TAFS BELOW... && .PREV DISCUSSION.../ISSUED 343 AM CST FRI DEC 19 2008/ FORECAST CONCERN NEAR TERM...WINTER WX ADV OVER SOUTHERN CWA. NICE SHORT WAVE LIFTING NORTHEAST ACROSS SOUTHERN IA THIS MORNING PER WATER VAPOR IMAGERY. HEAVIER SNOW BAND LINING UP FAIRLY WELL WITH 600 MB FULL WIND FRONTOGENESIS PER LATEST RUC. SNOW SHOULDNT MAKE IT TOO MUCH FARTHER THAN THIS BANDED REGION...WHICH SHOULD LIMIT SIG DEVELOPMENT INTO METRO PROPER. REMOVED A TIER OF COUNTIES AS BEST ACCUMS SOUTH. 5-6 INCHES ALREADY INTO WARNED AREA ALONG/SOUTH OF INTERSTATE 90. SHOULD SEE SOME 8-9 TOTALS CLOSE TO IOWA BORDER. FOCUS THEN TURNS TO NEXT SYSTEM MOVING IN LATER TONIGHT INTO WESTERN CWA. WATER VAPOR IMAGERY SHOWING THIS SYSTEM MOVING ACROSS NORTHWEST US NOW...AND WILL INTENSIFY AS IT MOVES INTO DAKOTAS LATER TONIGHT. FOLLOWED A SLOWER 00Z NAM/ECMWF FOR THE SFC FRONT...BUT STILL SHOULD BE NEAR THE DAKOTAS BORDER BY 12Z SAT. HAVE OPTED KEEP THE BLIZZARD/WINTER STORM WATCH GOING FOR NOW...BUT APPEARS BEST SNOWS WILL DEVELOP NORTHEAST OF THE STRONG WINDS...AT LEAST INTO SATURDAY AFTERNOON. ANY SNOW...AND PREVIOUS LIGHT SNOWS WILL CAUSE SIGNIFICANT BLOWING AND DRIFTING SNOW. THAT ALONG WITH FALLING TEMPERATURES/ARCTIC INTRUSION WILL MOST LIKELY GENERATE BLIZZARD CONDITIONS. SNOW TO CONTINUE AT LEAST ACROSS NORTHEAST QUADRANT OF CWA WELL INTO SUNDAY AS UPPER CLOSED LOW PIVOTS SLOWLY EAST DURING THIS PERIOD. COLDER AIR FILTERS INTO THE ENTIRE CWA LATER SUNDAY AND MONDAY...WITH WIND CHILLS BECOMING A PROBLEM. THEREAFTER...GFS AND ECMWF DIVERGE ON HOW STRONG THE NEXT SHORT WAVE DEVELOPS FOR TUESDAY INTO WEDNESDAY. GFS BECOMES MORE ZONAL WITH TIME AND SOUTHERN STREAM BECOMES ABOUT MORE ACTIVE. 00Z ECMWF MORE AMPLIFIED WITH TROUGH DEVELOPING OVER THE WESTERN US AND STORMS EJECTED NORTHEAST TOWARD UPPER MIDWEST EVERY 36 HOURS OR SO. STAY TUNED. .AVIATION.../18Z TAF ISSUANCE/ BUSY FORECAST THIS PERIOD WITH INITIAL CONCERNS REVOLVING AROUND CLOUD COVER THIS AFTERNOON WITH FOCUS SHIFTING TO SNOW RETURNING TO THE AREA LATE TONIGHT AND SATURDAY MORNING. MOSTLY VFR CEILINGS ACROSS THE AREA WITH A FEW AREAS SEEING BKN025-035 SKIES. HAZY CONDITIONS WITH 5 TO 9SM VISBY ALSO ENCOMPASS MOST OF THE AREA. BANDS OF MID CLOUDS BETWEEN 7000 AND 10000 FEET CONTINUE TO PASS OVER THE AREA AS WELL. WINDS ARE LESS THAN 10 KTS EARLY THIS AFTERNOON WITH VARIABLE DIRECTIONS BECOMING PREDOMINATELY NORTHEAST TO EAST THROUGH THE AFTERNOON. 1500 TO 2500 FT CIGS ARE EXPECTED TO RETURN THIS EVENING AS ANOTHER LOW PRESSURE SYSTEM RETURNS TO THE AREA. NEXT CONCERN IS ONSET OF SNOW LATER TONIGHT AND SATURDAY MORNING. TIMING OF ONSET IS THE MAIN CHALLENGE WITH CONFIDENCE IN TIMING NOT ALL THAT HIGH. A SFC AND MID LEVEL TROUGH WILL ENTER WESTERN MN LATE TONIGHT BRINGING WARM AIR ALOFT WHICH WILL TRIGGER SNOWFALL. SNOW WILL ARRIVE LATE TONIGHT IN WEST CENT MN...PROBABLY IN THE 07-10Z TIME FRAME AT KAXN AND IN THE 10-12Z TIME FRAME AT KSTC AND KRWF. SNOWFALL SHOULD BEGIN MID MORNING AT KMSP AND KRNH AND BY MIDDAY AT KEAU. TIMING OF ARRIVAL IS LEAST CERTAIN AT THESE SITES AND AM CONCERNED THE ONSET MAY BE QUICKER THAN WHAT IS NOW IN THE TAF. ONCE SNOW STARTS VISBYS BETWEEN 3/4 AND 1 1/2 SM ARE LIKELY WITH CIGS AROUND AND BELOW 1000 FT. EAST WINDS WILL BECOME SOUTHEAST THEN SOUTH THROUGH THE PERIOD. A TROUGH AXIS WILL BRING WINDS AROUND TO THE WEST FROM LATE MORNING WEST TO LATE AFTERNOON EAST WITH SPEEDS INCREASING BRINGING AT LEAST SOME BLOWING SNOW. DRY AIR QUICKLY WRAPS IN SATURDAY EVENING WHICH SHOULD ALLOW SNOW TO WIND DOWN BUT LOW CIGS LOOK TO REMAIN. SNOW AMOUNTS OF 4 TO AROUND 6 INCHES LOOK REASONABLE. WINDS WILL REALLY INCREASE SATURDAY EVENING WEST INTO SUNDAY MORNING EAST AS SOME SNOWFALL SETTLES INTO CENTRAL MN AND WEST CENT WI WITH 20 TO 30 KTS WINDS POSSIBLE...ESPECIALLY WEST. BLOWING AND DRIFTING WILL BE A REAL CONCERN EVEN IF LITTLE ADDITIONAL SNOW FALLS SUNDAY. WHITEOUT/BLIZZARD CONDITIONS ARE POSSIBLE ACROSS WEST CENT MN INCLUDING KRWF. THANKS TO ZMP CWSU FOR COORDINATION. ..MDB.. ZMP CWSU THOUGHTS INCLUDED... MAIN ISSUE EARLY IN TAF WILL BE HOW MUCH OF THE STRATOCU WILL PERSIST BETWEEN EXITING LOW PRESS SYSTEM AND NEXT ONE MOVING IN FM DKTS FOR SAT & SUN SNOW EVENT. NARROW BROKEN ENE-WSW STCU DECK OVER MSP AT 16Z PROBABLY GOING SCT AROUND 19Z FOLLOWED BY MID BKN-OVC MID-LEVEL CLOUDS ASSOC WITH WARM ADVECTION AT MID LEVELS ALREADY SPREADING TO SW MN. MORE LOW CLOUDS RETURNING QUICKLY 00Z TIME FRAME AS LOW LEVEL SYSTEM ORGANIZES OVER DKTS AND WARM ADVECTION AND RETURN TO ESE FLOW AT LOW LEVELS BRINGS BACK STRATUS DECK FOR OVERNIGHT. SNOW HOLDS OFF UNTIL 15-18Z SAT BUT CEILINGS DOWN NEAR 1700 FT BEFORE THAT AND INTO IFR CATEGORY WITH SNOW 18-00Z. WIND SHOULD REMAIN E TO ESE OVRNGT AND MOST OF SAT WITH DIRECTION SWITCH TO WSW-W AND SPEED INCREASE AT END OF 30HR TAF...00Z. ..AJB.. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR ANOKA-BENTON-CARVER-CHISAGO-DAKOTA-DOUGLAS- FREEBORN-GOODHUE-HENNEPIN-ISANTI-KANABEC-KANDIYOHI-LE SUEUR- MCLEOD-MEEKER-MILLE LACS-MORRISON-POPE-RAMSEY-RICE-SCOTT- SHERBURNE-SIBLEY-STEARNS-STEELE-TODD-WASECA-WASHINGTON- WRIGHT. BLIZZARD WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR BLUE EARTH-BROWN-CHIPPEWA-FARIBAULT-LAC QUI PARLE- MARTIN-NICOLLET-REDWOOD-RENVILLE-STEVENS-SWIFT-WATONWAN- YELLOW MEDICINE. WI...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE- POLK-RUSK-ST. CROIX. && $$ DWE/MDB/AJB mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 525 AM CST FRI DEC 19 2008 .AVIATION.../12Z TAF ISSUANCE/ CEILINGS ARE THE MAIN CONCERN THROUGH THE FORECAST PERIOD... WITH MOST OF THE MODEL GUIDANCE SUGGESTING MVFR CONDITIONS PREDOMINATING AND SOME POTENTIAL FOR IFR SUGGESTED AS WELL... PARTICULARLY FROM MOS. LATEST RADAR IMAGERY SHOWS SNOW CURRENTLY SKIRTING THE SOUTHEAST PORTION OF THE AREA... MAINLY IMPACTING KEAU... BUT ALSO HAVING A MINOR IMPACT ON KMSP AND POSSIBLY KRNH. THIS ACTIVITY WILL BRING SOME IFR AND MVFR VISIBILITIES TO KEAU EARLY THIS MORNING... WITH MVFR AT KMSP FOR THE FIRST HOUR OR SO... BUT SHOULD MOVE OUT QUICKLY AS THE QUICK MOVING SHORTWAVE SEEN OVER IOWA CONTINUE EASTWARD. IN ITS WAKE... THERE IS SOME UNCERTAINLY WITH THE CLOUD COVER SINCE THE MODELS CERTAINLY POINT TOWARD THINGS SATURATING IN THE 1-3K FT LAYER DURING THE MORNING HOURS OVER MOST OF THE AREA. WITH A LOW LEVEL COL MOVING IN AND A FAIR AMOUNT OF LINGERING BOUNDARY LAYER MOISTURE... THIS SEEMS LIKE A REASONABLE IDEA... AND THERE HAS BEEN SOME EXPANSION NOTED IN THE LOW CLOUDS OVER SOUTH DAKOTA AND SOUTHWEST MINNESOTA IN THE PAST FEW HOURS PER THE 11-3.9 MICRON SATELLITE IMAGERY... SO WILL CONTINUE TO FORECAST THIS OVERALL TREND TO CLOUDY MVFR CEILINGS AT ALL SITES THROUGH THE DAY... WHICH MATCHES UP WITH THE PREVIOUS FORECAST AS WELL. WILL NOT INCLUDE ANY SUB-1K FT CEILINGS AS SUGGESTED BY SOME OF THE MOS GUIDANCE... BUT THAT IS A POSSIBILITY THAT WILL NEED TO BE MONITORED. OTHERWISE... LIGHT NORTHEASTERLY WINDS WILL VEER SLOWLY THROUGH THE PERIOD OUT AHEAD OF THE NEXT SYSTEM WHICH WILL WORK TO INCREASE DEEP LAYER MOISTURE LATER TONIGHT. KEPT ANY MENTION OF PCPN WITH THIS SYSTEM OUT OF ALL BUT THE LONGER KMSP TAF... WHERE SOME MENTION IS INCLUDED TOWARD THE END OF THE FORECAST AS THE UPPER WAVE AND LOW LEVEL INVERTED TROUGH APPROACH THE AREA. && .PREV DISCUSSION... /ISSUED 343 AM CST FRI DEC 19 2008/ FORECAST CONCERN NEAR TERM...WINTER WX ADV OVER SOUTHERN CWA. NICE SHORT WAVE LIFTING NORTHEAST ACROSS SOUTHERN IA THIS MORNING PER WATER VAPOR IMAGERY. HEAVIER SNOW BAND LINING UP FAIRLY WELL WITH 600 MB FULL WIND FRONTOGENESIS PER LATEST RUC. SNOW SHOULDNT MAKE IT TOO MUCH FARTHER THAN THIS BANDED REGION...WHICH SHOULD LIMIT SIG DEVELOPMENT INTO METRO PROPER. REMOVED A TIER OF COUNTIES AS BEST ACCUMS SOUTH. 5-6 INCHES ALREADY INTO WARNED AREA ALONG/SOUTH OF INTERSTATE 90. SHOULD SEE SOME 8-9 TOTALS CLOSE TO IOWA BORDER. FOCUS THEN TURNS TO NEXT SYSTEM MOVING IN LATER TONIGHT INTO WESTERN CWA. WATER VAPOR IMAGERY SHOWING THIS SYSTEM MOVING ACROSS NORTHWEST US NOW...AND WILL INTENSIFY AS IT MOVES INTO DAKOTAS LATER TONIGHT. FOLLOWED A SLOWER 00Z NAM/ECMWF FOR THE SFC FRONT...BUT STILL SHOULD BE NEAR THE DAKOTAS BORDER BY 12Z SAT. HAVE OPTED KEEP THE BLIZZARD/WINTER STORM WATCH GOING FOR NOW...BUT APPEARS BEST SNOWS WILL DEVELOP NORTHEAST OF THE STRONG WINDS...AT LEAST INTO SATURDAY AFTERNOON. ANY SNOW...AND PREVIOUS LIGHT SNOWS WILL CAUSE SIGNIFICANT BLOWING AND DRIFTING SNOW. THAT ALONG WITH FALLING TEMPERATURES/ARCTIC INTRUSION WILL MOST LIKELY GENERATE BLIZZARD CONDITIONS. SNOW TO CONTINUE AT LEAST ACROSS NORTHEAST QUADRANT OF CWA WELL INTO SUNDAY AS UPPER CLOSED LOW PIVOTS SLOWLY EAST DURING THIS PERIOD. COLDER AIR FILTERS INTO THE ENTIRE CWA LATER SUNDAY AND MONDAY...WITH WIND CHILLS BECOMING A PROBLEM. THEREAFTER...GFS AND ECMWF DIVERGE ON HOW STRONG THE NEXT SHORT WAVE DEVELOPS FOR TUESDAY INTO WEDNESDAY. GFS BECOMES MORE ZONAL WITH TIME AND SOUTHERN STREAM BECOMES ABOUT MORE ACTIVE. 00Z ECMWF MORE AMPLIFIED WITH TROUGH DEVELOPING OVER THE WESTERN US AND STORMS EJECTED NORTHEAST TOWARD UPPER MIDWEST EVERY 36 HOURS OR SO. STAY TUNED. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL 9 AM CST THIS MORNING FOR BLUE EARTH-BROWN-DAKOTA-GOODHUE-LE SUEUR-MARTIN-NICOLLET-RICE- SCOTT-SIBLEY-STEELE-WASECA-WATONWAN. WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR ANOKA-BENTON-CARVER-CHISAGO-DAKOTA-DOUGLAS- FREEBORN-GOODHUE-HENNEPIN-ISANTI-KANABEC-KANDIYOHI-LE SUEUR- MCLEOD-MEEKER-MILLE LACS-MORRISON-POPE-RAMSEY-RICE-SCOTT- SHERBURNE-SIBLEY-STEARNS-STEELE-TODD-WASECA-WASHINGTON- WRIGHT. BLIZZARD WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR BLUE EARTH-BROWN-CHIPPEWA-FARIBAULT-LAC QUI PARLE- MARTIN-NICOLLET-REDWOOD-RENVILLE-STEVENS-SWIFT-WATONWAN- YELLOW MEDICINE. WINTER STORM WARNING UNTIL 9 AM CST THIS MORNING FOR FARIBAULT- FREEBORN. WI...WINTER WEATHER ADVISORY UNTIL 9 AM CST THIS MORNING FOR EAU CLAIRE-PEPIN-PIERCE. WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE- POLK-RUSK-ST. CROIX. && $$ TRH/DWE mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 400 AM CST FRI DEC 19 2008 .DISCUSSION... ...HEAVY LAKE EFFECT SNOW THROUGH TONIGHT... ...HEAVY SNOW ACROSS MOST OF THE NORTHLAND SATURDAY THROUGH SUNDAY... LAKE EFFECT SNOW BAND HAS SET UP NICELY OVER THE NORTH SHORE OF LAKE SUPERIOR BETWEEN TWO HARBORS AND DULUTH. THE BAND HAS BEEN SOMEWHAT RAGGED...THOUGH IS BEGINNING TO TAKE ON APPEARANCE OF SINGLE BAND STRUCTURE AS IT HAS SHIFTED NORTH OF KDLH. MEASURED ABOUT 0.5 INCH HERE AT THE OFFICE/AIRPORT IN TWO HOURS FROM MIDNIGHT TO 2A. MAX DBZ VALUES UP TO 34 WITH ECHO TOPS B/T 6 AND 7 KFT. MAY HAVE TO BUMP UP SNOW TOTALS IF THE BAND HOLDS TOGETHER...AS THERE COULD BE 1 INCH PER HOUR OR GREATER SNOW RATES. RUC13 HAS FAIRLY GOOD HANDLE ON ORIENTATION OF LAKE EFFECT THROUGH 12Z TODAY. LOW LEVEL CONVERGENCE APPARENT THIS MORNING...WITH WINDS SOUTHEASTERLY AT PORT WING...AND NORTHEASTERLY AT TWO HARBORS. LIMITED WIND SHEAR AT THE 1000 AND 925 MB LEVELS THROUGH AT LEAST 18Z SUPPORT SINGLE BAND STRUCTURE. IN ADDITION...THE ORIENTATION OF THE WINDS DOWN THE LONG AXIS OF THE LAKE...ALONG WITH TOPOGRAPHY AT THE HEAD OF THE LAKE...FAVOR SINGLE BAND STRUCTURE. THIS HOLDS TRUE FOR THE CHEQUAMEGON BAY/ASHLAND AREA AS WELL...IF WINDS BECOME MORE NORTHEASTERLY. WINDS CURRENTLY ALMOST DUE EAST... THOUGH BY 12Z WINDS BACK TO MORE EAST NORTHEASTERLY FOR THE REMAINDER OF FRIDAY. THIS WOULD BRING THE SNOW BAND BACK INTO THE DULUTH METRO. WILL HAVE TO CONTINUE TO MONITOR DOUGLAS/BAYFIELD/ASHLAND COUNTIES VERY CLOSELY THIS MORNING... AS WIND TRAJECTORY COULD FAVOR THE SOUTH SHORE TO GET IN ON HEAVIER SNOW AS WELL. MAY HAVE TO UPGRADE THESE AREAS TO A WARNING. THINKING IS STILL AN AVERAGE 6 TO 9 INCHES IN THE WARNING AREA...THOUGH IF A SINGLE BAND REMAINS OVER ANY ONE AREA...WOULD SEE UPWARDS OF GREATER THAN 12 INCHES THROUGH THE DAY FRIDAY. WINDS VEER SOUTHEASTERLY AFTER 06Z FRIDAY...BRINGING THE LAKE EFFECT POTENTIAL UP THE NORTH SHORE TO COOK COUNTY. ADDED AREAS OF BLOWING SNOW TODAY...AS WINDS NEAR THE HEAD OF THE LAKE WILL GUST UPWARDS OF 35-40 KTS TODAY. ATTENTION THEN TURNS TO WIDESPREAD SYNOPTIC SNOW EVENT SATURDAY AND SUNDAY. WILL LIKELY UPGRADE TO A WINTER STORM WARNING FOR SOUTHERN AND WESTERN PORTIONS OF CWA SOMETIME THIS MORNING OR EARLY AFTERNOON. MODELS CONSISTENT IN TIMING OF THE EVENT STARTING AROUND 12Z SATURDAY...AS STRONG WAVE DROPS SOUTHEASTWARD FROM THE HIGH PLAINS. TROWAL/INVERTED TROUGH FEATURE SETS UP AND REMAINS OVER THE NORTHLAND FOR ALL OF SATURDAY...PERHAPS INTO EARLY SUNDAY... PROLONGING SNOW EVENT. PERIOD OF ROBUST FGEN FORCING COULD PRODUCE A PERIOD OF HEAVY SNOW ON SATURDAY WITH GREATER THAN ONE INCH/HOUR SNOW RATES...MAINLY ACROSS SW ZONES...AS DEPICTED BY NAM/ECM X-SECTIONS. ALL IN ALL...WIDESPREAD SNOW TOTALS OF 8 INCHES OR MORE LOOK LIKELY FOR NE MN AND NW WI. SYSTEM BEGINS TO WIND DOWN ON SUNDAY...AS COLD ARCTIC AIR ONCE AGAIN MAKES A RETURN TO THE UPPER MIDWEST. HIGHS WILL ONLY REACH THE SINGLE DIGITS...WITH WIND CHILLS DROPPING WELL BELOW ZERO ONCE AGAIN ON GUSTY NORTHWEST WINDS. .EXTENDED...MONDAY THROUGH WEDNESDAY... RIDGE BUILDING IN FOR MONDAY WILL BRING A TEMPORARY BREAK IN THE SNOWY PATTERN...ALTHOUGH TEMPERATURES REMAIN WELL BELOW NORMAL FOR NEXT WEEK. NEXT PACIFIC WAVE WILL AFFECT THE REGION ON TUESDAY...AS INVERTED TROUGH FEATURE AND STATIONARY BOUNDARY SET UP ACROSS THE NORTHERN PLAINS. THIS SYSTEM WILL BRING THE POTENTIAL FOR SIGNIFICANT SNOW ACCUMULATIONS...CAUSING HAZARDOUS TRAVEL CONDITIONS ACROSS THE WESTERN GREAT LAKES REGION. DRY AND COLD HIGH PRESSURE LOOKS TO BUILD IN FOR WEDNESDAY. && .AVIATION...LAKE EFFECT SNOW SHOWERS ALONG THE NORTH SHORE AND HEAD OF LAKE SUPERIOR WILL CONTINUE TO RESULT IN IFR CONDITIONS NEAR OR AT THE KDLH TAF SITE TODAY. ELSEWHERE...MVFR STRATUS STRETCHED ACROSS PORTIONS OF NORTHEAST MINNESOTA IS EXPECTED TO EXPAND AND AFFECT ALL TAF SITES BY THIS AFTERNOON...WITH POSSIBLE LOWERING TO IFR CONDITIONS TONIGHT. && POINT TEMPS/POPS... DLH 17 11 15 5 / 90 60 100 100 INL 7 2 10 -7 / 20 40 90 90 BRD 16 12 14 -3 / 30 70 100 90 HYR 19 8 18 5 / 30 20 100 100 ASX 18 11 17 7 / 80 20 100 100 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH LATE SATURDAY NIGHT FOR CROW WING-KOOCHICHING-NORTHERN AITKIN-NORTHERN CASS-NORTHERN ITASCA-SOUTHERN AITKIN-SOUTHERN CASS-SOUTHERN ITASCA. LAKE EFFECT SNOW ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR SOUTHERN COOK/LAKESHORE. WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR CARLTON/SOUTHERN ST. LOUIS-CENTRAL ST. LOUIS- NORTHERN COOK/NORTHERN LAKE-NORTHERN ST. LOUIS-PINE- SOUTHERN COOK/LAKESHORE-SOUTHERN LAKE/LAKESHORE. LAKE EFFECT SNOW WARNING UNTIL MIDNIGHT CST TONIGHT FOR CARLTON/SOUTHERN ST. LOUIS-SOUTHERN LAKE/LAKESHORE. WI...LAKE EFFECT SNOW ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BAYFIELD-DOUGLAS. WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR ASHLAND-BAYFIELD-BURNETT-DOUGLAS-IRON-PRICE- SAWYER-WASHBURN. LS...HEAVY FREEZING SPRAY WARNING UNTIL 6 AM CST SATURDAY FOR LSZ121- LSZ140-LSZ141-LSZ142-LSZ143-LSZ144-LSZ145-LSZ146-LSZ147- LSZ148. SMALL CRAFT ADVISORY UNTIL 6 AM CST SATURDAY FOR LSZ121-LSZ140- LSZ141-LSZ142-LSZ143-LSZ144-LSZ145-LSZ146-LSZ147-LSZ148. $$ LONKA/LILES mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 343 AM CST FRI DEC 19 2008 .DISCUSSION... FORECAST CONCERN NEAR TERM...WINTER WX ADV OVER SOUTHERN CWA. NICE SHORT WAVE LIFTING NORTHEAST ACROSS SOUTHERN IA THIS MORNING PER WATER VAPOR IMAGERY. HEAVIER SNOW BAND LINING UP FAIRLY WELL WITH 600 MB FULL WIND FRONTOGENESIS PER LATEST RUC. SNOW SHOULDNT MAKE IT TOO MUCH FARTHER THAN THIS BANDED REGION...WHICH SHOULD LIMIT SIG DEVELOPMENT INTO METRO PROPER. REMOVED A TIER OF COUNTIES AS BEST ACCUMS SOUTH. 5-6 INCHES ALREADY INTO WARNED AREA ALONG/SOUTH OF INTERSTATE 90. SHOULD SEE SOME 8-9 TOTALS CLOSE TO IOWA BORDER. FOCUS THEN TURNS TO NEXT SYSTEM MOVING IN LATER TONIGHT INTO WESTERN CWA. WATER VAPOR IMAGERY SHOWING THIS SYSTEM MOVING ACROSS NORTHWEST US NOW...AND WILL INTENSIFY AS IT MOVES INTO DAKOTAS LATER TONIGHT. FOLLOWED A SLOWER 00Z NAM/ECMWF FOR THE SFC FRONT...BUT STILL SHOULD BE NEAR THE DAKOTAS BORDER BY 12Z SAT. HAVE OPTED KEEP THE BLIZZARD/WINTER STORM WATCH GOING FOR NOW...BUT APPEARS BEST SNOWS WILL DEVELOP NORTHEAST OF THE STRONG WINDS...AT LEAST INTO SATURDAY AFTERNOON. ANY SNOW...AND PREVIOUS LIGHT SNOWS WILL CAUSE SIGNIFICANT BLOWING AND DRIFTING SNOW. THAT ALONG WITH FALLING TEMPERATURES/ARCTIC INTRUSION WILL MOST LIKELY GENERATE BLIZZARD CONDITIONS. SNOW TO CONTINUE AT LEAST ACROSS NORTHEAST QUADRANT OF CWA WELL INTO SUNDAY AS UPPER CLOSED LOW PIVOTS SLOWLY EAST DURING THIS PERIOD. COLDER AIR FILTERS INTO THE ENTIRE CWA LATER SUNDAY AND MONDAY...WITH WIND CHILLS BECOMING A PROBLEM. THEREAFTER...GFS AND ECMWF DIVERGE ON HOW STRONG THE NEXT SHORT WAVE DEVELOPS FOR TUESDAY INTO WEDNESDAY. GFS BECOMES MORE ZONAL WITH TIME AND SOUTHERN STREAM BECOMES ABOUT MORE ACTIVE. 00Z ECMWF MORE AMPLIFIED WITH TROUGH DEVELOPING OVER THE WESTERN US AND STORMS EJECTED NORTHEAST TOWARD UPPER MIDWEST EVERY 36 HOURS OR SO. STAY TUNED. && .AVIATION.../06Z TAF ISSUANCE/ THE PRIMARY AVIATION CONCERN THIS TAF PERIOD IS THE ONSET OF SNOW. WEATHER CONDS HAD REMAIN VFR UP TO THIS POINT OVER MUCH OF SOUTHERN HALF OF MN AND WESTERN WISCONSIN. ONLY A FEW AREAS HAD REPORTED MVFR/IFR CONDS THURSDAY EVENING(KRWF). THE LATEST UPPER AIR DATA SHOWED MUCH OF THE COLUMN DRY BETWEEN THE LAYER 900 MB-700 MB OR ROUGHLY BETWEEN 3000 FT THROUGH 9000 FEET AGL. EXPECT WEATHER CONDS TO LOWER TO MARGINAL VFR FLYING CONDITIONS OVERNIGHT. VSBY LOWERING TO UNDER A MILE IN SNOW...ESPECIALLY SOUTH OF A LINE KRWF-KMSP TO KRNH BEFORE 500 AM. CLOUDS/CEILINGS EXPECTED TO STAY UNDER 3000 FEET THROUGH THE REST OF THE PERIOD. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL 9 AM CST THIS MORNING FOR BLUE EARTH-BROWN-DAKOTA-GOODHUE-LE SUEUR-MARTIN-NICOLLET-RICE- SCOTT-SIBLEY-STEELE-WASECA-WATONWAN. WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR ANOKA-BENTON-CARVER-CHISAGO-DAKOTA-DOUGLAS- FREEBORN-GOODHUE-HENNEPIN-ISANTI-KANABEC-KANDIYOHI-LE SUEUR- MCLEOD-MEEKER-MILLE LACS-MORRISON-POPE-RAMSEY-RICE-SCOTT- SHERBURNE-SIBLEY-STEARNS-STEELE-TODD-WASECA-WASHINGTON- WRIGHT. BLIZZARD WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR BLUE EARTH-BROWN-CHIPPEWA-FARIBAULT-LAC QUI PARLE- MARTIN-NICOLLET-REDWOOD-RENVILLE-STEVENS-SWIFT-WATONWAN- YELLOW MEDICINE. WINTER STORM WARNING UNTIL 9 AM CST THIS MORNING FOR FARIBAULT- FREEBORN. WI...WINTER WEATHER ADVISORY UNTIL 9 AM CST THIS MORNING FOR EAU CLAIRE-PEPIN-PIERCE. WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE- POLK-RUSK-ST. CROIX. && $$ DWE/TRH mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 951 AM CST FRI DEC 19 2008 .UPDATE...A WEAKENING BAND OF PREFRONTAL SHRA PUSHING INTO THE DELTA REGION WITH THE LAGGING FRONT NEAR A KCGI-KHOT-KTXK LINE. HAVE NUDGED HIGH TEMPS UPWARD A COUPLE OF DEGREES BASED ON LATEST HOURLY TRENDS COMPARED TO THURSDAY. NO CHANGES NEEDED TO ZONE PACKAGE AND UPDATED HOURLY GRIDS/GRAPHICS SHOULD BE POSTED ALREADY. LATEST RUC AND NAM12 KEEP THE FRONT STALLED ALONG A BASTROP TO COLUMBUS LINE TONIGHT. THEN A SURFACE WAVE DEVELOPS OVER ERN OK ON SATURDAY AND MOVES ALONG I-40 INTO TN SATURDAY EVENING. THIS WAVE SETS UP THE BIG COOL DOWN FOR SATURDAY NIGHT AS A NEW BATCH OF ARCTIC AIR PLUNGES OUR DIRECTION./40/ IN THE PREVIOUS DISCUSSION...LOOK FOR A DECENT BAND OF RAIN AND SOME SHOWERS JUST ALONG AND BEHIND THE FRONT. GUID POPS WERE 50-70% AND I HAVE INCREASED THOSE SOME 10% ACROSS THE CWA. THE FRONT SHOULD ENTER THE NW CWA AROUND 7-8 PM AND WASTE NO TIME MOVING ACROSS THE CWA. BY MIDNIGHT IT LOOKS TO BE APPROACHING THE TRACE CORRIDOR AND BY 12Z...EXITING THE FAR SE CWA. TEMPS WILL QUICKLY FALL INTO THE MID/UPPER 40S BEHIND THE FRONT. LOW TEMPS SAT NIGHT WILL LIKELY OCCUR BETWEEN 12-14Z SUNDAY MORNING AND RANGE FROM THE UPPER 30S NW TO UPPER 40S SE. SFC WINDS WILL BE RATHER BREEZY AS WELL WITH SUSTAINED WINDS BETWEEN 15-20KTS AND HIGHER GUSTS. SOME KIND OF WIND ADV PRODUCT WILL BE NEEDED. /CME/ LONG TERM(SUNDAY THROUGH NEXT FRIDAY)...OVER THE LONG TERM STRETCH WE WILL HAVE THE SHOT OF QUITE COLD ARCTIC AIR TO DEAL WITH FOR THE FIRST PART OF NEXT WEEK. THEN LIGHT RAIN MOVES IN FOR TUESDAY WITH PRECIPITATION AND WIND AND WARMER TEMPERATURES BUILDING THROUGH WEDNESDAY. THERE COULD BE A TOUCH OF WINTRY-WEATHER DURING THE ONSET OF THIS PRECIP. CHRISTMAS LOOKS DRY AT THIS POINT WITH AVERAGE TEMPS FOR THE HOLIDAY BUILDING TO ABOVE AVERAGE FOR THE END OF THE WEEK. MODELS CONTINUE TO SHOW GOOD OVERALL CONSENSUS WITH THE MENTIONED COLD SHOT COMING IN THE WAKE OF THE STRONG FRONTAL PASSAGE SATURDAY NIGHT. ANY RAIN LINGERING BEHIND THE FRONT SHOULD BE MOVING OUT SUNDAY MORNING WITH TEMPERATURES PROBABLY STRUGGLING TO RISE MUCH DURING THE DAY...AND SHOWING A TENDENCY TO FALL OFF BY MID-AFTERNOON. HIGHS SHOULD RANGE FROM THE UPPER 30S IN THE FAR NORTHWEST TO NEAR 50 IN FAR SOUTHEAST MISSISSIPPI. MEX STILL LOOKS A LITTLE TOO WARM DURING THE DAYTIME...BUT IS FINALLY SEEMING TO GRASP POTENTIAL FOR NO-JOKE COLD SUNDAY NIGHT. GUSTY WINDS DURING THE DAY SUNDAY SHOULD GRADUALLY DIMINISH LATER SUNDAY NIGHT WHICH WILL AID IN COOLING AND THE ARCTIC AIRMASS WILL TRANSPORT DEWPOINTS IN THE SINGLE DIGITS DOWN FROM THE NORTH. GUIDANCE FORECASTS LOWS IN THE MID TO UPPER TEENS UP NORTH ALONG THE HIGHWAY 82 CORRIDOR TO THE MID 20S DOWN SOUTH ALONG THE HIGHWAY 84 CORRIDOR. IF WINDS DIE DOWN MORE THAN FORECAST THEN GUIDANCE COULD STILL BE TOO WARM...BUT IT LOOKS PRETTY GOOD THIS GO ROUND. REFRAINED AT THIS POINT FROM MENTIONING ANYTHING IN THE HWO ABOUT THE COLD...BUT FORECASTED TEMPS ARE COMING SOMEWHAT CLOSE TO HARD FREEZE CRITERIA AND SUBSEQUENT SHIFTS WILL HAVE TO MONITOR. THE NEXT PIECE OF UPPER LEVEL ENERGY COMING THIS WAY WILL BEGIN SHOVING SOME HIGHER CLOUDS IN FROM THE WEST LATER MONDAY...BUT THE ARCTIC SURFACE HIGH WILL HOLD STRONG AND KEEP TEMPS CHILLY. FORECASTED 925 MB TEMPS REMAINING WELL BELOW 0 CELSIUS ALL DAY IN MOST CASES SUGGEST HIGHS STRUGGLING TO 40 DEGREES ON AVERAGE...AND GUIDANCE LOOKED TOO WARM. THIS HIGH WILL FINALLY START SHIFTING EAST MONDAY NIGHT AS THE NEXT SYSTEM GETS CLOSER AND SPILLS INCREASING MOISTURE ALOFT INTO THE LOWER MS VALLEY. THERE ARE STRONG SIGNALS FOR PRECIPITATION BEING GENERATED AT 5 TO 10 KFT MONDAY NIGHT OVER WESTERN ZONES DUE TO WARM AIR ADVECTION AND ISENTROPIC LIFT...BUT MUCH OF THIS PRECIP SHOULD EVAPORATE AS IT FALLS INTO A DRY BOUNDARY LAYER OF THE ATMOSPHERE. HOWEVER...WHAT DOES MAKE IT TO THE SURFACE HAS A DECENT CHANCE OF BEING SLEET. THIS POTENTIAL WAS INCLUDED IN THE OFFICIAL FORECAST...BUT TAKE NOTE THAT ANY WINTRY-TYPE PRECIP FALLING IN THE REGION MONDAY NIGHT THROUGH EARLY TUESDAY SHOULD BE VERY LIGHT AND RATHER QUICK TO SWITCH OVER TO RAIN. SUBSEQUENT SHIFTS WILL CONTINUE TO MONITOR POTENTIAL. TUESDAY AND TUESDAY NIGHT WILL FEATURE GRADUALLY INCREASING RAIN CHANCES AND GRADUALLY INCREASING TEMPERATURES AS THE COLD AIRMASS COMPLETELY LOSES ITS GRIP AND SOUTHERLY FLOW STRENGTHENS BIG TIME ACROSS THE ARKLAMISS. BY LATER TUESDAY NIGHT AND WEDNESDAY THE GFS MODEL DEPICTS AN EXTREMELY POTENT DISTURBANCE IMPACTING OUR REGION...WHICH WOULD BRING THREATS FROM HEAVY RAIN AND THUNDERSTORMS. HOWEVER...THE SOMETIMES MORE RELIABLE (IN WINTER) EUROPEAN MODEL DEPICTS THIS DISTURBANCE PASSING WELL TO THE NORTH AND THUS PRODUCING TAMER WEATHER. GFS ENSEMBLES SHOW SOME AGREEMENT WITH THE OPERATIONAL GFS WITH THE CANADIAN MODEL SOMEWHAT ON THE GFS TRAIN AS WELL. WITH THAT IN MIND I GENERALLY STUCK WITH GFS GUIDANCE TEMPERATURES AND POPS FOR TUESDAY THROUGH WEDNESDAY NIGHT...ALTHOUGH I WILL NOT START TALKING UP THE POTENTIAL FOR HAZARDOUS WEATHER IN FORECAST PRODUCTS DUE TO HIGH UNCERTAINTY. DIFFERENCES BETWEEN THE EUROPEAN AND GFS MODELS REMAIN FROM THIS POINT INTO NEXT WEEKEND WITH THE EURO DEVELOPING EXTREME UPPER LEVEL RIDGING OVER THE VICINITY OF THE DEEP SOUTH (WHICH WOULD RESULT IN VERY WARM TEMPERATURES). THE GFS LOOKS WARM AS WELL...BUT NOT TO THE SAME DEGREE...AND IT ALSO FEATURES POTENTIAL FOR FRONTAL IMPACT (WHICH THE EURO DOES NOT). /BB/ && .AVIATION...MOSTLY BROKEN MVFR CEILINGS TODAY WITH PERIODS OF VFR CONDITIONS BETWEEN 18-02Z OR SO. MVFR CEILINGS WILL LIKELY REDEVELOP TONIGHT AND WITH LESS WIND...A FEW LOCATIONS MAY DROP TO IFR FOR A SHORT TIME...ESPECIALLY NEAR THE FRONTAL ZONE ALONG HIGHWAY 82. SFC WINDS TODAY WILL BE DECENT FOR AREAS ALONG AND N OF I-20. LOOK FOR SWLY WINDS 10-15KTS WITH SOME HIGHER GUSTS AT TIMES...SHIFTING WLY OVER THE DELTA REGION AND THEN NLY FOR A FEW HOURS AFTER 00Z./19/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 76 58 74 42 / 13 12 13 77 MERIDIAN 76 58 74 44 / 13 12 12 79 VICKSBURG 76 59 74 41 / 14 12 14 70 HATTIESBURG 78 59 76 48 / 13 10 11 65 NATCHEZ 76 61 76 43 / 13 10 12 65 GREENVILLE 74 57 71 37 / 26 27 51 67 GREENWOOD 73 56 72 37 / 26 28 56 77 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 948 PM CST SAT DEC 20 2008 .UPDATE... MINOR FORECAST UPDATES MADE TO ACCOUNT FOR CLOUD COVERAGE TRENDS AS WELL AS TWEAKING DEWPOINTS AND TEMPERATURES DOWNWARD TONIGHT. STRONG ARCTIC HIGH PRESSURE OVER THE NORTHERN ROCKIES IS SENDING A VERY COLD AIRMASS INTO THE REGION. TEMPERATURES ARE ALREADY WELL INTO THE TEENS ACROSS MUCH OF THE AREA WITH WIND CHILL VALUES ALREADY DIPPING BELOW ZERO IN THE OSAGE PLAINS OF EXTREME SOUTHEAST KANSAS AND WEST CENTRAL MISSOURI. THIS AIRMASS WILL BE TRAVELING OVER SNOW/ICE PACK AND MAINTAIN ITS INTEGRITY QUITE WELL. AS A RESULT...SINGLE DIGIT LOWS ARE LIKELY TONIGHT ACROSS MUCH OF THE AREA. WITH A STRONG PRESSURE GRADIENT IN PLACE...WINDS WILL REMAIN BLUSTERY IN THE 15 TO 25 MPH RANGE. CURRENT WIND CHILL ADVISORY IS WELL PLACED AND MOST LOCALES WILL HAVE WIND CHILL VALUES BETWEEN -10 AND -15 TONIGHT. A CURSORY GLANCE AT INCOMING MODEL OUTPUT CONFIRMS A VERY COLD DAY SUNDAY AS IT WILL BE TOUGH TO CRACK 20F IN MANY AREAS. SUNDAY NIGHT IS SHAPING UP TO BE OUR COLDEST NIGHT OF THE SEASON TO THIS POINT. && .DISCUSSION... THE BEGINNING OF THE BITTER COLD WEATHER FOR THE NEXT SEVERAL DAYS STARTED AS THE ARCTIC COLD FRONT PUSHED THROUGH THE OZARKS BY EARLY THIS AFTERNOON. THE REGION WILL SEE TEMPERATURES FALL INTO THE TEENS BY MIDNIGHT TONIGHT. WITH THE GUSTY SURFACE WINDS PROGGED TO REMAIN 15 TO 25 MPH WITH GUSTS TO 30MPH ALREADY STARTING...DECIDED TO MOVE THE START TIME ON THE WIND CHILL ADVISORY UP THREE HOUR TO MIDNIGHT...WHEN TEMPERATURES WILL REACH THE BORDERLINE FOR -5 DEGREE WIND CHILLS. MODELS AGAIN WERE ABOUT 3 HOURS SLOW ON THE TIMING OF THE COLD AIR THIS AFTERNOON WITH FWC GUIDANCE ACTUALLY THE CLOSEST TO REALITY PROVIDING ANOTHER REASON TO MOVE UP THE ONSET OF THE WIND CHILL ADVISORY. THE MET/MAV WERE CONSIDERABLY TOO WARM. STRONG COLD AIR ADVECTION WILL CONTINUE SUNDAY AS SURFACE PRESSURE BUILDS SOUTH ACROSS THE PLAINS. 850 MB TEMPERATURES ARE STILL PROGGED TO BE NEAR MINUS 20 DEGREES CELSIUS. DESPITE MORE SUNSHINE TEMPERATURES WILL STRUGGLE TO RISE FROM MORNING LOWS. EXPECT READINGS TO ONLY REACH THE TEENS ACROSS MOST OF THE FORECAST AREA. WINDS WILL SUBSIDE SUNDAY NIGHT AS THE SURFACE HIGH BUILDS INTO THE OZARKS. TEMPERATURES WILL PLUMMET INTO THE SINGLE DIGITS AS THE CORE OF THE ARCTIC AIRMASS SETTLES INTO THE AREA. A LOCATION OR TWO MAY FALL TO ZERO. THE WIND CHILL ADVISORY MAY NEED TO BE EXTENDED INTO SUNDAY NIGHT. A SLOW MODERATING TREND WILL BEGIN MONDAY AS THE SURFACE HIGH SLIDES EAST. HOWEVER TEMPERATURES WILL REMAIN BELOW FREEZING MONDAY. THE RETURN FLOW WILL STRENGTHEN MONDAY NIGHT AS LEE SIDE CYCLOGENESIS DEVELOPS IN RESPONSE TO THE NEXT APPROACHING TROUGH. THIS WILL CAUSE TEMPERATURES TO STEADY OFF AND EVEN RISE MONDAY NIGHT. INCREASING WARM AIR AND MOISTURE ADVECTION OVER TOP THE ARCTIC DOME WILL RESULT IN INCREASING CLOUDS MONDAY NIGHT AND PRECIPITATION DEVELOPMENT TUESDAY. QUESTIONS REMAIN ON THE TYPE AND INTENSITY OF PRECIPITATION TUESDAY. MODEL SOUNDINGS SUGGEST THAT WINTRY PRECIPITATION IN THE FORM OF FREEZING RAIN AND SLEET WILL FALL ACROSS MUCH OF THE FORECAST AREA TUESDAY MORNING. THE QUESTION THEN BECOMES HOW QUICK TO TEMPERATURES WARM. NAM MODEL BOUNDARY LAYER TEMPERATURES ARE CONSIDERABLY COLDER THAN THE GFS WHICH TYPICALLY DOES NOT HANDLE SHALLOW ARCTIC AIRMASSES THAT WELL. FOLLOWED A BLEND OF THE TWO MODELS WITH A TRANSITION TO RAIN DURING THE AFTERNOON. IT WOULD NOT BE SURPRISING IF WINTRY PRECIPITATION CONTINUED MOST OF THE DAY ACROSS THE EASTERN OZARKS WHERE THE ARCTIC AIRMASS WILL BE MORE ENTRENCHED. WHILE AMOUNTS LOOK TO BE ON THE LIGHT SIDE ENOUGH WINTRY PRECIPITATION COULD CAUSE TRAVEL DIFFICULTIES TUESDAY. IT APPEARS THAT TEMPERATURES WILL CONTINUE TO RISE TUESDAY EVENING AS WARM AIR ADVECTION CONTINUES AHEAD OF THE APPROACHING FRONT. WINTRY PRECIPITATION MAY AGAIN DEVELOP LATER TUESDAY NIGHT INTO EARLY WEDNESDAY BEHIND THE FRONT. THIS LOOKS TO BE A QUICK SHOT AS THE SHORTWAVE TROUGH SWINGS QUICKLY ACROSS THE REGION. ACCUMULATION... IF ANY...LOOKS TO BE LIGHT. THE UPPER PATTERN BEGINS TO TRANSITION THE REMAINDER OF THE WEEK AS AN UPPER TROUGH FORMS OUT WEST. THIS WILL RESULT IN A BROAD SOUTHWESTERLY FLOW ACROSS THE REGION. SHORTWAVE TROUGHS RIDING THROUGH THIS FLOW WILL BRING UNSETTLED WEATHER AND MORE UNCERTAINTY TO THE FORECAST. GRADUALLY WARMING ALONG WITH THE POTENTIAL OF PRECIPITATION WILL DEVELOP DURING LATE WEEK. IT APPEARS ANY PRECIPITATION THAT DOES DEVELOP WILL BE LIQUID. FOSTER && .AVIATION... FOR THE 00Z TAF PACKAGE...PRIMARY FORECAST CHALLENGE WILL BE QUICKLY DEPARTING STRATUS DECK. IR 11-3.9 SAT IMAGERY INDICATES THAT THE BACK EDGE OF LOW END MVFR STRATUS DECK IS THROUGH FORT SCOTT. THIS FEATURE LINES UP NICELY WITH A SUBTLE 850MB THERMAL TROUGH WHICH THE RUC13 PROGS TO BE RATHER PROGRESSIVE. AS SUCH HAVE CLEARED SKIES DURING THE NEXT FEW HOURS AT BOTH TAF SITES. VFR IS EXPECTED FOR THE REMAINDER OF THE TAF. STRONG ARCTIC HIGH PRESSURE WILL STILL BE CENTERED WELL TO OUR NORTHWEST TONIGHT... THUS HAVE MAINTAINED GUSTY NORTHWEST WINDS THROUGH THE NIGHT. GAGAN && .SGF WATCHES/WARNINGS/ADVISORIES... MO...WIND CHILL ADVISORY UNTIL 12 PM CST SUNDAY FOR MOZ055>058- 066>071-077>083-088>094-101-102. KS...WIND CHILL ADVISORY UNTIL 12 PM CST SUNDAY FOR KSZ073-097-101. && $$ mo AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE SPRINGFIELD MO 524 PM CST SAT DEC 20 2008 ...UPDATE TO AVIATION... .DISCUSSION... THE BEGINNING OF THE BITTER COLD WEATHER FOR THE NEXT SEVERAL DAYS STARTED AS THE ARCTIC COLD FRONT PUSHED THROUGH THE OZARKS BY EARLY THIS AFTERNOON. THE REGION WILL SEE TEMPERATURES FALL INTO THE TEENS BY MIDNIGHT TONIGHT. WITH THE GUSTY SURFACE WINDS PROGGED TO REMAIN 15 TO 25 MPH WITH GUSTS TO 30MPH ALREADY STARTING...DECIDED TO MOVE THE START TIME ON THE WIND CHILL ADVISORY UP THREE HOUR TO MIDNIGHT...WHEN TEMPERATURES WILL REACH THE BORDERLINE FOR -5 DEGREE WIND CHILLS. MODELS AGAIN WERE ABOUT 3 HOURS SLOW ON THE TIMING OF THE COLD AIR THIS AFTERNOON WITH FWC GUIDANCE ACTUALLY THE CLOSEST TO REALITY PROVIDING ANOTHER REASON TO MOVE UP THE ONSET OF THE WIND CHILL ADVISORY. THE MET/MAV WERE CONSIDERABLY TOO WARM. STRONG COLD AIR ADVECTION WILL CONTINUE SUNDAY AS SURFACE PRESSURE BUILDS SOUTH ACROSS THE PLAINS. 850 MB TEMPERATURES ARE STILL PROGGED TO BE NEAR MINUS 20 DEGREES CELSIUS. DESPITE MORE SUNSHINE TEMPERATURES WILL STRUGGLE TO RISE FROM MORNING LOWS. EXPECT READINGS TO ONLY REACH THE TEENS ACROSS MOST OF THE FORECAST AREA. WINDS WILL SUBSIDE SUNDAY NIGHT AS THE SURFACE HIGH BUILDS INTO THE OZARKS. TEMPERATURES WILL PLUMMET INTO THE SINGLE DIGITS AS THE CORE OF THE ARCTIC AIRMASS SETTLES INTO THE AREA. A LOCATION OR TWO MAY FALL TO ZERO. THE WIND CHILL ADVISORY MAY NEED TO BE EXTENDED INTO SUNDAY NIGHT. A SLOW MODERATING TREND WILL BEGIN MONDAY AS THE SURFACE HIGH SLIDES EAST. HOWEVER TEMPERATURES WILL REMAIN BELOW FREEZING MONDAY. THE RETURN FLOW WILL STRENGTHEN MONDAY NIGHT AS LEE SIDE CYCLOGENESIS DEVELOPS IN RESPONSE TO THE NEXT APPROACHING TROUGH. THIS WILL CAUSE TEMPERATURES TO STEADY OFF AND EVEN RISE MONDAY NIGHT. INCREASING WARM AIR AND MOISTURE ADVECTION OVER TOP THE ARCTIC DOME WILL RESULT IN INCREASING CLOUDS MONDAY NIGHT AND PRECIPITATION DEVELOPMENT TUESDAY. QUESTIONS REMAIN ON THE TYPE AND INTENSITY OF PRECIPITATION TUESDAY. MODEL SOUNDINGS SUGGEST THAT WINTRY PRECIPITATION IN THE FORM OF FREEZING RAIN AND SLEET WILL FALL ACROSS MUCH OF THE FORECAST AREA TUESDAY MORNING. THE QUESTION THEN BECOMES HOW QUICK TO TEMPERATURES WARM. NAM MODEL BOUNDARY LAYER TEMPERATURES ARE CONSIDERABLY COLDER THAN THE GFS WHICH TYPICALLY DOES NOT HANDLE SHALLOW ARCTIC AIRMASSES THAT WELL. FOLLOWED A BLEND OF THE TWO MODELS WITH A TRANSITION TO RAIN DURING THE AFTERNOON. IT WOULD NOT BE SURPRISING IF WINTRY PRECIPITATION CONTINUED MOST OF THE DAY ACROSS THE EASTERN OZARKS WHERE THE ARCTIC AIRMASS WILL BE MORE ENTRENCHED. WHILE AMOUNTS LOOK TO BE ON THE LIGHT SIDE ENOUGH WINTRY PRECIPITATION COULD CAUSE TRAVEL DIFFICULTIES TUESDAY. IT APPEARS THAT TEMPERATURES WILL CONTINUE TO RISE TUESDAY EVENING AS WARM AIR ADVECTION CONTINUES AHEAD OF THE APPROACHING FRONT. WINTRY PRECIPITATION MAY AGAIN DEVELOP LATER TUESDAY NIGHT INTO EARLY WEDNESDAY BEHIND THE FRONT. THIS LOOKS TO BE A QUICK SHOT AS THE SHORTWAVE TROUGH SWINGS QUICKLY ACROSS THE REGION. ACCUMULATION... IF ANY...LOOKS TO BE LIGHT. THE UPPER PATTERN BEGINS TO TRANSITION THE REMAINDER OF THE WEEK AS AN UPPER TROUGH FORMS OUT WEST. THIS WILL RESULT IN A BROAD SOUTHWESTERLY FLOW ACROSS THE REGION. SHORTWAVE TROUGHS RIDING THROUGH THIS FLOW WILL BRING UNSETTLED WEATHER AND MORE UNCERTAINTY TO THE FORECAST. GRADUALLY WARMING ALONG WITH THE POTENTIAL OF PRECIPITATION WILL DEVELOP DURING LATE WEEK. IT APPEARS ANY PRECIPITATION THAT DOES DEVELOP WILL BE LIQUID. FOSTER && .AVIATION... FOR THE 00Z TAF PACKAGE...PRIMARY FORECAST CHALLENGE WILL BE QUICKLY DEPARTING STRATUS DECK. IR 11-3.9 SAT IMAGERY INDICATES THAT THE BACK EDGE OF LOW END MVFR STRATUS DECK IS THROUGH FORT SCOTT. THIS FEATURE LINES UP NICELY WITH A SUBTLE 850MB THERMAL TROUGH WHICH THE RUC13 PROGS TO BE RATHER PROGRESSIVE. AS SUCH HAVE CLEARED SKIES DURING THE NEXT FEW HOURS AT BOTH TAF SITES. VFR IS EXPECTED FOR THE REMAINDER OF THE TAF. STRONG ARCTIC HIGH PRESSURE WILL STILL BE CENTERED WELL TO OUR NORTHWEST TONIGHT... THUS HAVE MAINTAINED GUSTY NORTHWEST WINDS THROUGH THE NIGHT. GAGAN && .SGF WATCHES/WARNINGS/ADVISORIES... MO...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 12 PM CST SUNDAY FOR MOZ055>058-066>071-077>083-088>094-101-102. KS...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 12 PM CST SUNDAY FOR KSZ073-097-101. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 629 PM EST FRI DEC 19 2008 .SYNOPSIS... THE WINTER STORM WHICH BROUGHT HEAVY SNOWFALL TO THE REGION TODAY WILL MOVE OFF THE EAST COAST TONIGHT. THE STEADIER SNOWS WILL QUICKLY TAPER OFF FROM WEST TO EAST DURING THE EVENING HOURS. ANY LINGERING LAKE EFFECT SNOW SHOWERS BEHIND THIS SYSTEM WILL DIMINISH DURING SATURDAY...THEN ANOTHER SIGNIFICANT WINTER STORM WILL AFFECT THE AREA SUNDAY AND MONDAY. THIS STORM SYSTEM WILL BRING THE POTENTIAL FOR A WIDESPREAD MODERATE SNOWFALL TO THE AREA SUNDAY...FOLLOWED BY THE POTENTIAL FOR SIGNIFICANT LAKE EFFECT SNOWS SUNDAY NIGHT AND MONDAY ALONG WITH STRONG WINDS. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... THE FORECAST IS WORKING OUT BEAUTIFULLY THIS AFTERNOON WITH TIMING...AMOUNTS...AND INTENSITY OF SNOWFALL ALMOST SPOT ON. REGIONAL RADAR IMAGERY SHOWS THE HEAVIEST SNOW NOW LIFTING NORTH INTO AREAS ALONG AND NORTH OF THE THRUWAY FROM ROCHESTER WEST AND ALSO PUSHING INTO ALL OF CENTRAL AND NORTHERN NEW YORK. THIS IS IN RESPONSE TO A MID LEVEL DRY SLOT WORKING NORTHEAST ACROSS THE AREA IN ADVANCE OF THE MID LEVEL CIRCULATION. MOISTURE CHANNEL IMAGERY SHOWING VERY STRONG UPPER LEVEL DIVERGENCE JUST AHEAD OF THE MAIN MID LEVEL CIRCULATION AND COMMA HEAD...WITH OBJECTIVE RUC ANALYSIS SHOWING A 110+ KNOT 500MB JET MAX ROUNDING THE BASE OF THE TROUGH THROUGH CENTRAL OHIO. UPSTREAM RADARS CONTINUE TO SHOW AN AREA OF MODERATE TO HEAVY SNOW IN THE COMMA HEAD ACROSS SOUTHERN ONTARIO AND SOUTHEAST LOWER MICHIGAN...AND THIS IS SHOWING SIGNS OF RAPID EXPANSION ON THE KBUF RADAR OVER THE PAST 45 MINUTES FROM HAMILTON TO LONG POINT. EXPECT THIS TO CROSS THE NORTHERN HALF OF THE CWA FROM LATE AFTERNOON THROUGH EARLY EVENING WITH ONE LAST SHOT OF HEAVY SNOW AS THE MID LEVEL CIRCULATION CROSSES THE CWA. A MIX OF SLEET AND FREEZING RAIN MADE IT AS FAR NORTH AS ABOUT CATTARAUGUS CREEK AT MIDDAY...AND NOW THIS AREA WHICH HAS THE WARMER AIR ALOFT IS ESSENTIALLY DRY SLOTTED...WITH JUST SCATTERED LIGHT SHOWERS OF FREEZING RAIN/SLEET AND SNOW AND SOME FREEZING DRIZZLE. EXPECT THIS LIGHT MIX TO CONTINUE FOR ANOTHER HOUR OR TWO BEFORE COLDER AIR ALOFT COMES BACK IN AND CHANGES ANY REMAINING PRECIP BACK TO SNOW. EXPECT STORM TOTALS TO REACH 7 TO 10 INCHES ACROSS MUCH OF THE CWA INCLUDING BUFFALO TO ROCHESTER TO OSWEGO. TOTALS WILL BE HELD DOWN TO ABOUT 5 INCHES OR SO IN THE SOUTHERN TIER WHERE THERE WAS A MIX WITH SLEET AND FREEZING RAIN. EAST OF LAKE ONTARIO THE HEAVY SNOW IS MAKING IT A LITTLE FURTHER NORTH THAN ANTICIPATED...SO WE SHOULD BE ABLE TO REALIZE TOTALS OF 6-9 INCHES EVEN ALL THE WAY NORTH TO THE SAINT LAWRENCE RIVER. IN ADDITION TO THE HEAVY SNOWFALL...NORTHEAST WINDS CONTINUE TO INCREASE...ESPECIALLY ACROSS THE NIAGARA FRONTIER WHERE THE WINDS ARE COMING IN OFF THE LOW FRICTION SURFACE OF LAKE ONTARIO. EXPECT WINDS TO GUST TO 25-30 KNOTS THROUGH MID EVENING WITH EVEN HIGHER GUSTS ALONG THE LAKE ONTARIO SHORE FROM HILTON TO YOUNGSTOWN. SIGNIFICANT BLOWING AND DRIFTING WILL CONTINUE TO CAUSE NEAR WHITEOUT CONDITIONS THROUGH THE EVENING...ESPECIALLY NEAR LAKE ONTARIO. LATER THIS EVENING THE SNOW WILL QUICKLY TAPER OFF FROM WEST TO EAST AS THE MID LEVEL SYSTEM RACES EASTWARD. THE SNOW MAY LINGER A LITTLE LONGER ALONG THE SOUTH SHORE OF LAKE ONTARIO WITH SOME MINOR LAKE ENHANCEMENT OFF LAKE ONTARIO IN THE NORTHEAST WINDS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/... FOR THE MOST PART...SATURDAY LOOKS TO BE THE LULL BETWEEN THE WINTER STORM TODAY AND THE NEXT WINTER STORM BEGINNING LATE SATURDAY NIGHT. THERE COULD BE SOME VERY MINOR LINGERING LAKE EFFECT SNOW SHOWERS SOUTH OF LAKE ONTARIO...FROM ROCHESTER TO THE NIAGARA RIVER AS THE FLOW STILL REMAINS NORTHEASTERLY...BUT A FAIR AMOUNT OF SHEAR DOES SHOW UP IN MODEL SOUNDINGS. ANY LAKE SNOWS WILL COMPLETELY CUT OFF BY MID DAY SATURDAY...AS FLOW VEERS SOUTHEASTERLY AHEAD OF THE NEXT WAVE OF LOW PRESSURE DEVELOPING OUT OF THE SOUTHERN PLAINS. OUR FOCUS WILL THEN TURN TO THE EVOLUTION OF THE NEXT STORM SYSTEM WHICH WILL BEGIN TO IMPACT THE AREA LATE SATURDAY NIGHT. THE SURFACE LOW LIFTING OUT OF THE SOUTHERN PLAINS LOOKS TO LIFT UP ACROSS THE NIAGARA PENINSULA JUST WEST OF BUFFALO BY SUNDAY MORNING...AS A SECONDARY LOW BEGINS TO DEVELOPS OFF THE MID ATLANTIC COAST. STRENGTHENING WARM AIR ADVECTION PATTERN WILL BRING A MODEST AMOUNT OF ISENTROPIC ASCENT ACROSS THE AREA LATE SATURDAY NIGHT AND DURING THE DAY SUNDAY...COMBINED WITH A GOOD INFLUX OF BOTH GULF AND ATLANTIC MOISTURE WHICH SHOULD PRODUCE A GENERAL SNOWFALL ACROSS ALL OF WESTERN OF CENTRAL NEW YORK. MODEL QPF FIELDS AND LATEST HPC GUIDANCE SUGGESTING SNOWFALL AMOUNTS COULD BE IN THE RANGE OF 1-3/2-4 INCHES ACROSS THE SOUTHERN TIER...AND 3-6 INCHES ACROSS MOST OF THE REMAINDER OF THE AREA...BUT MAY BE A BIT MORE EAST OF LAKE ONTARIO WHERE SNOWS MAY HANG ON A BIT LONGER. ALTHOUGH THIS SYNOPTIC SNOW EVENT DOES NOT LOOK AS IMPRESSIVE AS THE ONE WE HAD TODAY AND THIS EVENING THERE WILL BE THE ADDITIONAL COMPONENT OF STRONG SURFACE WIND FIELDS AS THE GRADIENT TIGHTENS AS A COASTAL LOW LOOKS TO FORM OF THE NEW ENGLAND COAST BY LATE SUNDAY. WE EXPECT CONSIDERABLE BLOWING AND DRIFTING POTENTIAL ALONG WITH DRASTICALLY REDUCED VISIBILITIES AT TIMES. LATE IN THE DAY SUNDAY AND SUNDAY NIGHT AS THE COASTAL LOW BECOMES THE DOMINATE FEATURE WORKING UP THE NEW ENGLAND COAST...A VERY IMPRESSIVE SURGE OF ARCTIC AIR WILL RAPIDLY SPREAD INTO THE AREA ON A DEVELOPING WELL ALIGNED LOW LEVEL SOUTHWESTERLY FLOW. WE ARE BECOMING INCREASINGLY CONCERNED ABOUT THE POTENTIAL OF A VERY SIGNIFICANT LAKE EVENT SNOW EVENT FOR THE BUFFALO METRO AREA OR JUST TO THE SOUTH...THE STRONG WIND FIELDS WILL LIKELY CARRY THESE SIGNIFICANT LAKE SNOWS WELL INLAND LIKELY REACHING TO THE ROCHESTER AREA AND INTO PORTIONS OF THE FINGER LAKES. LAKE EFFECT PARAMETERS ARE VERY FAVORABLE FOR HEAVY LAKE SNOWS WITH THE EXCEPTION FOR THE LIMITING POTENTIAL OF STRONG WINDS WHICH MAY TEND TO STRETCH AND TEAR APART ANY ORGANIZED BANDS. WE WILL NOT ISSUE HEADLINES AT THIS POINT...WITH STILL SOME PLACEMENT AND INTENSITY ISSUES TO PIN DOWN, BUT IF LATER MODEL DATA MAINTAINS CONTINUITY A SIGNIFICANT LAKE EFFECT SNOWSTORM WILL IMPACT THE BUFFALO AREA INTO THE SOUTHERN TIER LATE SUNDAY AND ON INTO MONDAY. THE SAME CONCERNS WILL CARRY OVER TO AREAS EAST OF LAKE ONTARIO INCLUDING THE WATERTOWN AREA. POTENTIALLY HEAVY LAKE SNOWS WILL LIKELY IMPACT THIS AREA SUNDAY NIGHT INTO THE DAY MONDAY. MOMENTUM TRANSFER SCHEME OF LATEST BUFKIT DATA SUGGESTING THE POTENTIAL FOR WIND GUSTS IN EXCESS OF 45 MPH LATE IN THE DAY SUNDAY AND INTO THE FIRST HALF OF MONDAY. WIND HEADLINES MAY ALSO NEED TO BE ISSUED IN LATER FORECASTS. BOUNDARY LAYER WINDS SHOULD VEER MORE NORTHWESTERLY MONDAY AND SHOULD PUSH THE LAKE BANDS FURTHER TO THE SOUTH INTO THE SOUTHERN TIER OFF LAKE ERIE AND SOUTHEAST OF LAKE ONTARIO BETWEEN ROCHESTER AND OSWEGO. MODELS SOUNDING ARE SUGGESTING THE POTENTIAL FOR INCREASING SHEAR ALOFT THEREFORE INTENSITY OF THE LAKE SNOWS ARE IN QUESTION DURING THIS TIME...BUT THIS TIME PERIOD WILL HAVE TO BE MONITORED AS WELL FOR SIGNIFICANT LAKE SNOWS ACROSS THE WESTERN SOUTHERN TIER AND FROM ROCHESTER TO OSWEGO COUNTY OFF LAKE ONTARIO. && .LONG TERM /TUESDAY THROUGH FRIDAY/... QUIETER WEATHER IS THEN EXPECTED TO FINALLY RETURN DURING TUESDAY AS HIGH PRESSURE BUILDS INTO THE LOWER LAKES REGION. ANY WEAK LINGERING LAKE SNOWS FROM MONDAY NIGHT SHOULD LIFT NORTH INTO THE BUFFALO AND WATERTOWN AREAS WITH TIME AND EVENTUALLY DISSIPATE COMPLETELY AS THE LOW-LEVEL STEERING FLOW BECOMES MORE SOUTHWESTERLY...SHEAR INCREASES DRAMATICALLY...AND DRY ADVECTION CONTINUES AT THE LOW LEVELS. LATER IN THE PERIOD...THE LATEST GFS AND ECMWF STILL SUGGEST THE POTENTIAL FOR ANOTHER SYSTEM TO IMPACT THE AREA DURING CHRISTMAS EVE AND THE FIRST PART OF CHRISTMAS DAY. THIS COULD RESULT IN ANOTHER ROUND OF ACCUMULATING SNOWS DURING THIS TIME FRAME IF TEMPS REMAIN COLD ENOUGH...THOUGH THIS APPEARS SOMEWHAT QUESTIONABLE GIVEN GFS/ECMWF INDICATIONS OF A FAIRLY DEEP SOUTHERLY FLOW OF MILDER AIR OVER THE AREA FOR AT LEAST PART OF WEDNESDAY...WHICH MIGHT BE WARM ENOUGH TO SUPPORT A RAIN/SNOW MIX OR EVEN SOME RAIN INITIALLY. GIVEN ALL THAT WE HAVE GOING ON OVER THE COURSE OF THE NEXT FEW DAYS...WILL OPT TO STICK WITH CONTINUITY AND INDICATE MAINLY SNOW FOR THIS TIME FRAME FOR NOW...WITH THE THOUGHT THAT PTYPE MAY BE NEED TO BE REVISITED WITH FUTURE FORECASTS. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... UPPER LOW CROSSING THE FORECAST AREA THIS EVENING WILL BRING MOST OF THE STEADY SNOW TO AN END. ALREADY WINDING DOWN ACROSS THE WESTERN COUNTIES WITH KBUF/KIAG/KJHW SHOWING VSBY IMPROVEMENT WITH SOMW BREAKS IN THE LOW CLOUD DECK...EXPECT KROC AND KART TO IMPROVE AFTER 02Z. THERE WILL BE SOME LAKE EFFECT FOR KIAG AND KROC AND ALL SITES WILL LIKELY REMAIN AT MVFR WITH LOW LEVEL MOISTURE MAINTAINING THE MVFR CEILINGS. NOT MUCH CEILING IMPROVEMENT EXPECTED ON SATURDAY WITH NORTHERLY WINDS BRINGING COLD AIR ACROSS LAKE ONTARIO PRODUCING 1500FT TO 2500FT CLOUD DECK. OUTLOOK... SATURDAY...MAINLY VFR. SUNDAY...IFR IN WIDESPREAD SNOW...BLOWING SNOW. STRONG WINDS. MONDAY...MVFR WITH LOCAL IFR IN LAKE EFFECT SNOW EAST SHIFTING SOUTHEAST OF THE LAKES. TUESDAY...MAINLY VFR. WEDNESDAY...MVFR IN RAIN/SNOW. && .MARINE... LOW PRESSURE OVER NORTHERN PENNSYLVANIA THIS AFTERNOON WILL TRACK EAST OFF THE JERSEY COAST TONIGHT. NORTHEASTERLY GALES WILL CONTINUE ON BOTH LAKE ERIE AND LAKE ONTARIO THROUGH THIS EVENING. THE WINDS AND ASSOCIATED WAVE WILL SUBSIDE OVERNIGHT AS THE LOW PULLS WELL OUT INTO THE ATLANTIC. THE STRONG NORTHEAST WINDS CAUSED WATER LEVELS TO DROP ABOUT 2 FEET ON THE EASTERN END OF LAKE ERIE EARLIER THIS AFTERNOON...BUT WATER LEVELS ARE STARTING TO RISE BACK UP. SATURDAY SHOULD BE QUITE ON THE LAKES AS A RIDGE OF HIGH PRESSURE DRIFTS EAST ACROSS THE LOWER LAKES REGION. ANOTHER DEEPENING LOW PRESSURE SYSTEM IS THEN EXPECTED TO EVOLVE OFF THE EAST COAST BY LATE IN THE DAY SUNDAY. GALE FORCE WINDS WILL BE HIGHLY LIKELY ON BOTH LAKES FROM LATE SUNDAY INTO MONDAY...WITH THE POTENTIAL FOR WIND GUSTS TO APPROACH STORM FORCE. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR NYZ001>008-010>014-085. WINTER STORM WARNING UNTIL 8 PM EST THIS EVENING FOR NYZ019>021. MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LEZ020. LOW WATER ADVISORY UNTIL 9 PM EST THIS EVENING FOR LEZ020- 040-041. GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LEZ040-041. GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LOZ042>045-062>065. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR SLZ022-024. && $$ SYNOPSIS...TMA NEAR TERM...HITCHCOCK SHORT TERM...TMA LONG TERM...JJR AVIATION...WCH MARINE...TMA ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 237 PM EST FRI DEC 19 2008 .SYNOPSIS... A SIGNIFICANT WINTER STORM OVER MISSOURI EARLY THIS MORNING WILL RACE EASTWARD TODAY...REACHING PITTSBURGH BY EARLY THIS AFTERNOON...AND THE JERSEY COAST BY THIS EVENING. THIS SYSTEM WILL PRODUCE A WIDESPREAD HEAVY SNOWFALL ACROSS THE AREA TODAY AND EARLY THIS EVENING...WITH THE STEADIER SNOWS THEN QUICKLY TAPERING OFF FROM WEST TO EAST DURING THE MID AND LATE EVENING HOURS. ANY LINGERING LAKE EFFECT SNOW SHOWERS BEHIND THIS SYSTEM WILL DIMINISH DURING SATURDAY...THEN ANOTHER SIGNIFICANT WINTER STORM WILL AFFECT THE AREA SUNDAY AND MONDAY. && .NEAR TERM /THROUGH TONIGHT/... THE FORECAST IS WORKING OUT BEAUTIFULLY THIS AFTERNOON WITH TIMING...AMOUNTS...AND INTENSITY OF SNOWFALL ALMOST SPOT ON. REGIONAL RADAR IMAGERY SHOWS THE HEAVIEST SNOW NOW LIFTING NORTH INTO AREAS ALONG AND NORTH OF THE THRUWAY FROM ROCHESTER WEST AND ALSO PUSHING INTO ALL OF CENTRAL AND NORTHERN NEW YORK. THIS IS IN RESPONSE TO A MID LEVEL DRY SLOT WORKING NORTHEAST ACROSS THE AREA IN ADVANCE OF THE MID LEVEL CIRCULATION. MOISTURE CHANNEL IMAGERY SHOWING VERY STRONG UPPER LEVEL DIVERGENCE JUST AHEAD OF THE MAIN MID LEVEL CIRCULATION AND COMMA HEAD...WITH OBJECTIVE RUC ANALYSIS SHOWING A 110+ KNOT 500MB JET MAX ROUNDING THE BASE OF THE TROUGH THROUGH CENTRAL OHIO. UPSTREAM RADARS CONTINUE TO SHOW AN AREA OF MODERATE TO HEAVY SNOW IN THE COMMA HEAD ACROSS SOUTHERN ONTARIO AND SOUTHEAST LOWER MICHIGAN...AND THIS IS SHOWING SIGNS OF RAPID EXPANSION ON THE KBUF RADAR OVER THE PAST 45 MINUTES FROM HAMILTON TO LONG POINT. EXPECT THIS TO CROSS THE NORTHERN HALF OF THE CWA FROM LATE AFTERNOON THROUGH EARLY EVENING WITH ONE LAST SHOT OF HEAVY SNOW AS THE MID LEVEL CIRCULATION CROSSES THE CWA. A MIX OF SLEET AND FREEZING RAIN MADE IT AS FAR NORTH AS ABOUT CATTARAUGUS CREEK AT MIDDAY...AND NOW THIS AREA WHICH HAS THE WARMER AIR ALOFT IS ESSENTIALLY DRY SLOTTED...WITH JUST SCATTERED LIGHT SHOWERS OF FREEZING RAIN/SLEET AND SNOW AND SOME FREEZING DRIZZLE. EXPECT THIS LIGHT MIX TO CONTINUE FOR ANOTHER HOUR OR TWO BEFORE COLDER AIR ALOFT COMES BACK IN AND CHANGES ANY REMAINING PRECIP BACK TO SNOW. EXPECT STORM TOTALS TO REACH 7 TO 10 INCHES ACROSS MUCH OF THE CWA INCLUDING BUFFALO TO ROCHESTER TO OSWEGO. TOTALS WILL BE HELD DOWN TO ABOUT 5 INCHES OR SO IN THE SOUTHERN TIER WHERE THERE WAS A MIX WITH SLEET AND FREEZING RAIN. EAST OF LAKE ONTARIO THE HEAVY SNOW IS MAKING IT A LITTLE FURTHER NORTH THAN ANTICIPATED...SO WE SHOULD BE ABLE TO REALIZE TOTALS OF 6-9 INCHES EVEN ALL THE WAY NORTH TO THE SAINT LAWRENCE RIVER. IN ADDITION TO THE HEAVY SNOWFALL...NORTHEAST WINDS CONTINUE TO INCREASE...ESPECIALLY ACROSS THE NIAGARA FRONTIER WHERE THE WINDS ARE COMING IN OFF THE LOW FRICTION SURFACE OF LAKE ONTARIO. EXPECT WINDS TO GUST TO 25-30 KNOTS THROUGH MID EVENING WITH EVEN HIGHER GUSTS ALONG THE LAKE ONTARIO SHORE FROM HILTON TO YOUNGSTOWN. SIGNIFICANT BLOWING AND DRIFTING WILL CONTINUE TO CAUSE NEAR WHITEOUT CONDITIONS THROUGH THE EVENING...ESPECIALLY NEAR LAKE ONTARIO. LATER THIS EVENING THE SNOW WILL QUICKLY TAPER OFF FROM WEST TO EAST AS THE MID LEVEL SYSTEM RACES EASTWARD. THE SNOW MAY LINGER A LITTLE LONGER ALONG THE SOUTH SHORE OF LAKE ONTARIO WITH SOME MINOR LAKE ENHANCEMENT OFF LAKE ONTARIO IN THE NORTHEAST WINDS. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... ON SATURDAY...WE WILL BE IN THE LULL IN BETWEEN TODAY`S WINTER STORM...AND THE NEXT STORM SYSTEM THAT WILL BE AFFECTING OUR AREA BEGINNING LATER SATURDAY NIGHT. THERE MAY STILL BE SOME LINGERING LAKE EFFECT SNOW SHOWERS SOUTHWEST OF LAKE ONTARIO DURING THE MORNING OWING TO A CONTINUED NORTHEASTERLY LOW LEVEL FLOW OF SUFFICIENTLY COLD AIR ACROSS THE LAKE...BUT LOW /~5 KFT/ LAKE EQLS...LIMITED MOISTURE...AND FAIR AMOUNT OF SHEAR SHOULD RESULT IN THIS ACTIVITY BEING RATHER INSIGNIFICANT IN NATURE. AS SUCH...WILL CONTINUE TO JUST CARRY LOW TO MID RANGE CHANCE POPS FROM MONROE COUNTY WESTWARD ACROSS THE NIAGARA FRONTIER IN THE MORNING...THEN DROP THESE BACK TO SLIGHT CHANCE OR LOWER FOR THE AFTERNOON AS THE LOW LEVEL FLOW BECOMES MORE SHEARED/MORE SOUTHEASTERLY AND PUSHES ANY LINGERING WEAK ACTIVITY OUT INTO THE LAKE. THEREAFTER...OUR FOCUS WILL BE ON THE NEXT STORM SYSTEM THAT IS FORECAST TO LIFT NORTHEASTWARD FROM THE PLAINS STATES LATER SATURDAY AND SATURDAY NIGHT. WHILE THERE ARE STILL SOME DIFFERENCES IN THE MODELS WITH RESPECT TO THE TRACK OF THIS SYSTEM...THE 19/00Z NAM/GFS/ECMWF ARE IN ROUGH AGREEMENT ON A DOUBLE-BARRELED LOW STRUCTURE EVOLVING WITH TIME...WITH A PRIMARY LOW LIFTING NORTHEAST ACROSS THE CENTRAL LAKES/SOUTHERN ONTARIO DURING SUNDAY...AND A SECONDARY COASTAL SYSTEM DEVELOPING AND LIFTING FROM THE CAROLINAS TO NEW ENGLAND DURING THE SAME TIME FRAME. A STRENGTHENING WARM AIR ADVECTION PATTERN OUT AHEAD OF THESE TWO LOWS WILL RESULT IN A FAIR AMOUNT OF ASCENT ACROSS THE AREA LATER SATURDAY NIGHT AND SUNDAY...AND THIS WILL INTERACT WITH A GOOD INFLUX OF GULF AND ATLANTIC MOISTURE TO PRODUCE A GENERAL SNOWFALL ACROSS ALL OF WESTERN AND CENTRAL NEW YORK. LATEST MODEL QPF FIELDS SUGGEST THE POTENTIAL FOR ADVISORY-LEVEL ACCUMS OF 3 TO 6 INCHES ACROSS MOST OF THE AREA DURING THIS TIME FRAME...PERHAPS 5 TO 9 INCHES ACROSS THE NORTH COUNTRY WHICH WILL REMAIN UNDER THE SYNOPTIC PRECIP SHIELD THE LONGEST. AS WE GET INTO SUNDAY AFTERNOON...A SURFACE OCCLUDED FRONT CONNECTING THE TWO LOWS IS EXPECTED TO GRADUALLY LIFT NORTHEAST ACROSS THE AREA...WITH A BRIEF PERIOD OF DRY SLOTTING WORKING INTO THE AREA FOLLOWING ITS PASSAGE. THIS WILL ALLOW THE STEADIER SYNOPTIC SNOWS TO TAPER OFF TO SOME SCATTERED SNOW SHOWERS FOR SEVERAL HOURS SATURDAY AFTERNOON...BEFORE A SECONDARY AREA OF WRAPAROUND PRECIP WORKS BACK ACROSS THE AREA SUNDAY NIGHT ALONG WITH SOME ADDITIONAL MINOR ACCUMS. HAVE ADJUSTED POPS TO TRY AND BETTER REFLECT THIS OVERALL TREND IN THE SYNOPTIC PRECIP...GENERALLY DROPPING THESE BACK TO CHANCE FOR A FEW HOURS EVERYWHERE SUNDAY AFTERNOON...BEFORE RAISING THEM BACK TO AT LEAST LIKELY EVERYWHERE SUNDAY NIGHT AS THE WRAPAROUND PRECIP PUSHES INTO THE AREA. COMPLICATING FORECAST MATTERS SUNDAY AFTERNOON AND EVENING WILL BE MESOSCALE LAKE EFFECT PROCESSES. WITH THE PASSAGE OF THE SURFACE OCCLUDED FRONT...MUCH COLDER AIR ALOFT WILL BEGIN WORKING INTO THE AREA FROM THE WEST AND SOUTHWEST DURING THE AFTERNOON AND EVENING...WITH 850 MB TEMPS PLUMMETING TO -12C TO -16C BY SUNDAY EVENING...AND TO -15C TO -18C BY MIDNIGHT. THIS WILL RESULT IN PLENTY OF LAKE-INDUCED INSTABILITY...AND THIS COMBINED WITH FAIRLY DEEP MOISTURE AND WELL ALIGNED STEERING WINDS WILL ALLOW SIGNIFICANT LAKE EFFECT SNOWS TO DEVELOP DOWNWIND OF THE GREAT LAKES DURING SUNDAY AFTERNOON AND EARLY SUNDAY EVENING. THE MAIN FORECAST QUESTION AT THIS POINT WITH RESPECT TO THE LAKE EFFECT IS EXACTLY WHERE THE LAKE EFFECT SNOWS WILL DEVELOP. THE 19/00Z NAM AND TO A LESSER EXTENT THE 19/00Z ECMWF MAINTAIN THE PRIMARY LOW A LITTLE BIT LONGER...AND AS A RESULT INDICATE A WSW LOW LEVEL FLOW THAT WOULD RESULT IN THE LAKE SNOWS INITIALLY IMPACTING THE BUFFALO/WATERTOWN AREAS FOR A WHILE LATER SUNDAY AFTERNOON AND EVENING...BEFORE DRIFTING SOUTHWARD LATER IN THE EVENING/OVERNIGHT AS THE FLOW BECOMES MORE NORTHWESTERLY. MEANWHILE...THE 19/00Z GFS PLACES MORE EMPHASIS ON THE SECONDARY COASTAL LOW...AND AS A RESULT INDICATES MORE OF A WESTERLY LOW LEVEL FLOW THAT WOULD CAUSE THE LAKE SNOWS TO INITIALLY FORM A LITTLE TO THE SOUTH OF THE BUFFALO AND WATERTOWN AREAS SUNDAY AFTERNOON AND EVENING...THEN SWEEP SOUTHWARD SUNDAY EVENING AS THE FLOW BECOMES MORE NORTHWESTERLY. GIVEN THE MODEL DIFFERENCES MENTIONED ABOVE AND INHERENT FORECAST UNCERTAINTIES THIS FAR OUT IN TIME...IT REMAINS RATHER DIFFICULT TO PROJECT EXACTLY WHICH AREAS WILL BE MOST INFLUENCED BY THE LAKE SNOWS THROUGH SUNDAY EVENING. AS SUCH...WILL JUST INDICATE A BROAD AREA OF LAKE-ENHANCED CATEGORICAL POPS EAST OF THE LAKES FOR NOW SUNDAY AFTERNOON AND EVENING...THEN SHIFT THE AREAS OF ENHANCED POPS SOUTH TO AREAS SOUTHEAST OF THE LAKES LATER IN THE NIGHT AS THE MODELS ARE IN GOOD AGREEMENT ON THE FLOW BECOMING MORE NORTHWESTERLY. AS IF ALL OF THIS WAS NOT ENOUGH...AN ADDITIONAL COMPLICATING FACTOR SUNDAY AND SUNDAY NIGHT WILL BE STRENGTHENING SURFACE WIND FIELDS AS THE PRESSURE GRADIENT TIGHTENS BEHIND THE DEVELOPING COASTAL LOW. BUFKIT SOUNDINGS CONTINUE TO SUGGEST THE POTENTIAL FOR SUSTAINED WINDS OF 20-30 MPH AND WIND GUSTS IN EXCESS OF 40 MPH...WHICH WILL CREATE CONSIDERABLE BLOWING/DRIFTING AND VISIBILITY PROBLEMS... ESPECIALLY IN AREAS IMPACTED BY THE LAKE SNOWS. FOR MONDAY...A VERY COLD NORTHWEST FLOW REGIME WITH 850 MB TEMPERATURES DOWN TO NEAR MINUS 18C...WILL LINGER ACROSS THE LOWER GREAT LAKES AS THE COASTAL LOW LIFTS OUT ACROSS THE CANADIAN MARITIMES. THIS WILL ALLOW ADDITIONAL SIGNIFICANT LAKE EFFECT SNOWS TO CONTINUE SOUTHEAST OF LAKE ERIE...AND ALONG THE SOUTH SHORE OF LAKE ONTARIO. THE HEAVIEST LAKE SNOWS DURING THIS TIME FRAME SHOULD IMPACT AREAS SOUTHEAST OF THE BUFFALO AREA...AS WELL AREAS FROM THE ROCHESTER EAST TO OSWEGO COUNTY. AMOUNTS ARE HARD TO PIN DOWN THIS FAR OUT...BUT FAVORABLE LAKE PARAMETERS SUGGEST THE POTENTIAL FOR ADDITIONAL SIGNIFICANT ACCUMS...WITH STILL-BRISK WINDS AGAIN CAUSING PROBLEMS WITH BLOWING AND DRIFTING SNOW. THE LAKE SNOWS ARE EXPECTED TO CONTINUE INTO MONDAY NIGHT...THOUGH THESE SHOULD BE GRADUALLY LIFTING NORTH AND WEAKENING WITH TIME AS WINDS BACK TO MORE OF A WESTERLY DIRECTION...WARM ADVECTION BEGINS ALOFT...AND DRIER AIR BEGINS WORKING IN FROM THE CENTRAL LAKES. && .LONG TERM /TUESDAY THROUGH THURSDAY/... QUIETER WEATHER IS THEN EXPECTED TO FINALLY RETURN DURING TUESDAY AS HIGH PRESSURE BUILDS INTO THE LOWER LAKES REGION. ANY WEAK LINGERING LAKE SNOWS FROM MONDAY NIGHT SHOULD LIFT NORTH INTO THE BUFFALO AND WATERTOWN AREAS WITH TIME AND EVENTUALLY DISSIPATE COMPLETELY AS THE LOW-LEVEL STEERING FLOW BECOMES MORE SOUTHWESTERLY...SHEAR INCREASES DRAMATICALLY...AND DRY ADVECTION CONTINUES AT THE LOW LEVELS. LATER IN THE PERIOD...THE LATEST GFS AND ECMWF STILL SUGGEST THE POTENTIAL FOR ANOTHER SYSTEM TO IMPACT THE AREA DURING CHRISTMAS EVE AND THE FIRST PART OF CHRISTMAS DAY. THIS COULD RESULT IN ANOTHER ROUND OF ACCUMULATING SNOWS DURING THIS TIME FRAME IF TEMPS REMAIN COLD ENOUGH...THOUGH THIS APPEARS SOMEWHAT QUESTIONABLE GIVEN GFS/ECMWF INDICATIONS OF A FAIRLY DEEP SOUTHERLY FLOW OF MILDER AIR OVER THE AREA FOR AT LEAST PART OF WEDNESDAY...WHICH MIGHT BE WARM ENOUGH TO SUPPORT A RAIN/SNOW MIX OR EVEN SOME RAIN INITIALLY. GIVEN ALL THAT WE HAVE GOING ON OVER THE COURSE OF THE NEXT FEW DAYS...WILL OPT TO STICK WITH CONTINUITY AND INDICATE MAINLY SNOW FOR THIS TIME FRAME FOR NOW...WITH THE THOUGHT THAT PTYPE MAY BE NEED TO BE REVISITED WITH FUTURE FORECASTS. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... WIDESPREAD VLIFR CONDITIONS WILL CONTINUE THIS AFTERNOON ACROSS ALL OF WESTERN AND NORTH CENTRAL NY WITH VSBY BELOW LANDING MINIMUMS... PREVENTING ANY AIRCRAFT OPERATIONS FOR ALL BUT TYPE II AND TYPE III QUALIFIED AIRCRAFT AND AIRCREWS. THE HEAVY SNOW WILL BECOME MORE INTERMITTENT THIS AFTERNOON FROM WEST TO EAST AND THEN EVENTUALLY TAPER OFF THIS EVENING AS THE SYSTEM MOVES RAPIDLY EAST. AFTER 20Z HAVE PLACED THE HEAVY SNOW IN A TEMPO GROUP AT KBUF-KIAG AND AFTER 21Z AT KROC TO SIGNIFY THE MORE INTERMITTENT NATURE OF THE SNOW. BRISK NORTHEAST WINDS WILL CONTINUE TO PRODUCE SIGNIFICANT BLOWING AND DRIFTING SNOW ACROSS RUNWAYS THROUGH THIS EVENING. THE SNOW HAS PROBABLY CHANGED OVER TO SLEET AND FREEZING RAIN AT KJHW BASED ON VISIBILITY...ALTHOUGH SINCE THERE IS NO PRESENT WEATHER SENSOR ON THE KJHW AWOS III EQUIPMENT WE CANNOT VERIFY THIS. THE MIX WILL CONTINUE THROUGH AT LEAST MID AFTERNOON BEFORE CHANGING BACK TO SNOW. LATER TONIGHT THE SNOW WILL TAPER OFF WITH VSBY RETURNING TO VFR... ALTHOUGH THE CIGS ARE EXPECTED TO REMAIN MVFR THROUGH TONIGHT AND SATURDAY MORNING AS ABUNDANT LOW LEVEL MOISTURE AND NORTHEAST UPSLOPE FLOW CONTINUE. OUTLOOK... SATURDAY...MAINLY VFR. SUNDAY...IFR IN WIDESPREAD SNOW...BLOWING SNOW. STRONG WINDS. MONDAY...MVFR WITH LOCAL IFR IN LAKE EFFECT SNOW EAST SHIFTING SOUTHEAST OF THE LAKES. TUESDAY...MAINLY VFR. WEDNESDAY...MVFR IN RAIN/SNOW. && .MARINE... LOW PRESSURE OVER MISSOURI EARLY THIS MORNING WILL WORK ACROSS THE OHIO VALLEY AND SOUTHERN PENNSYLVANIA TODAY...THEN OFF THE JERSEY COAST TONIGHT. NORTHEASTERLY WINDS ON LAKES ERIE AND LAKE ONTARIO WILL STRENGTHEN TO GALE FORCE TODAY AS THE PRESSURE GRADIENT TIGHTENS WITH THE APPROACH OF THE LOW...THEN PERSIST AT GALE FORCE INTO THIS EVENING BEFORE DIMINISHING OVERNIGHT AS THE LOW PULLS WELL OUT INTO THE ATLANTIC. THIS WILL BE FOLLOWED BY RELATIVELY QUIET CONDITIONS ON SATURDAY AS A RIDGE OF HIGH PRESSURE DRIFTS EAST ACROSS THE LOWER LAKES REGION. ANOTHER DEEPENING LOW PRESSURE SYSTEM IS THEN EXPECTED TO EVOLVE OFF THE EAST COAST BY LATE IN THE DAY SUNDAY. GALE FORCE WINDS WILL BE HIGHLY LIKELY ON BOTH LAKES FROM LATE SUNDAY INTO MONDAY...WITH THE POTENTIAL FOR WIND GUSTS TO APPROACH STORM FORCE. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR NYZ001>008-010>014-085. WINTER STORM WARNING UNTIL 8 PM EST THIS EVENING FOR NYZ019>021. MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LEZ020. LOW WATER ADVISORY UNTIL 9 PM EST THIS EVENING FOR LEZ020- 040-041. GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LEZ040-041. GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LOZ042>045-062>065. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR SLZ022-024. && $$ SYNOPSIS...JJR NEAR TERM...HITCHCOCK SHORT TERM...JJR LONG TERM...JJR AVIATION...HITCHCOCK MARINE...JJR ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 443 AM EST SAT DEC 20 2008 .SYNOPSIS... A COLD FRONT WILL PUSH S THROUGH THE AREA TODAY AND STALL NEAR THE SOUTHERN PORTION OF THE AREA OR OVER THE COASTAL WATERS. THE FRONT WILL RETURN N OVER THE AREA TONIGHT AS LOW PRESSURE MOVES INTO THE CAROLINAS FROM THE W. LOW PRESSURE WILL LIFT NE OF THE AREA SUNDAY DRAGGING A COLD FRONT THROUGH THE AREA. STRONG AND COLD HIGH PRESSURE WILL BUILD BEHIND THE FRONT SUNDAY NIGHT INTO MONDAY...N OF THE AREA TUESDAY...THEN OFFSHORE BY WEDNESDAY. && .NEAR TERM /THROUGH TODAY/... AS OF 300AM SATURDAY...SFC LOW PRESSURE IS MOVING QUICKLY E FROM THE MID ATLC COAST WITH AN ASSOCIATED COLD FRONT SLIDING S THROUGH SE VIRGINIA. ALOFT...ZONAL FLOW DOMINATES WHICH IS ADVECTING SOME HIGH CLOUDS E THROUGH THE AREA. THE FRONT TO OUR N IS EXPECTED TO DROP S THROUGH THE AREA LATER THIS MORNING THROUGH EARLY AFTERNOON...THO THERE REMAINS SOME QUESTION TO IF THE FRONT WILL CLEAR THE ENTIRE CWA WITH MINIMAL SUPPORT. MODEL CONSENSUS SUGGESTS THE BOUNDARY WILL REACH A POSN BETWEEN THE CORE BANKS AND DUPLIN COUNTY BY 18Z THEN MAYBE DRIFT A LITTLE FURTHER S BEFORE STALLING. POST FRONTAL SFC N/NE WINDS AND ASSOCIATED SHALLOW CAA WILL LIKELY LEAD TO A PERIOD OF DROPPING TEMPS DURING THE AFTERNOON WHICH ALWAYS MAKES THE TEMP GRIDS CHALLENGING...AND STILL THINK A VARIETY OF TEMPS WILL BE FELT TODAY WITH GENERALLY HIGHS IN THE U50S/L60S N AND M-U60S S. SOME LOCATIONS WILL LIKELY SEE MAX TEMPS IN THE MORNING AHEAD OF THE FRONT...ESP NRN HALF OF CWA WHERE TEMPS HAVE NOT FALLEN BELOW THE L60S THUS FAR TONITE WITH MILD SW FLOW. HAVE THUS USED A RUC/NAM12 BLEND FOR HOURLY TEMPS IN THE NEAR TERM INSTEAD OF THE NORMAL CLIMO DIURNAL CURVE. MOISTURE AND CLOUD COVER IS EXPECTED TO INCREASE THROUGH THE 2ND HALF OF THE DAY AS OUR FRONT BEGINS STALLING AND 850MB WAA BEGINS OVER RIDING THE SHALLOW POST FRONTAL SFC WINDS. CONTINUED TO BRING IN POPS AFTER 18Z...HIGHEST OVER THE SW PART WHICH IS IN LINE WITH THE NWP CONSENSUS AND WHERE OUR FRONT IS EXPECTED TO STALL...AND WHERE MID LEVEL MOIST AIR ADVECTION EXPECTED TO BE MAXIMIZED LATER TODAY. && .SHORT TERM /TONIGHT THROUGH MONDAY/... STILL SETTING UP TO BE A MESSY NIGHT. OUR SLOW MOVING FRONTAL BOUNDARY WILL DRIFT N IN RESPONSE TO SFC LOW PRES MOVING E/NE THROUGH THE CAROLINAS. STRONG 850MB WAA PATTERN WILL PERSIST WHICH WILL AID IN LIFT IN ADDITION TO STEEPENING MID LVL LAPSE RATES...AS A DEEP CUT OFF LOW MOVES SE TO E THROUGH THE SRN GREAT LAKES REGION. ALL OF THE MODELS ARE INIDICATING A PERIOD OF MODERATE RAINFALL WITH THIS PATTERN ESPECIALLY OVER THE NRN HALF OF AREA WHERE WE HAVE INCREASED POPS TO CATEGORICAL...AND GENERALLY HAVE LIKELY ELSEWHERE. ALSO ADDED A SCHC TSTMS FOR POTENTIAL FOR ELEVATED CONVECTION WITH OMEGA EXPECTED TO BE MAXIMIZED BTWN 850-500MB. SVR THREAT APPEARS TO BE MINIMAL OVER OUR AREA BUT WILL NEED TO WATCH FOR SOME GUSTY WINDS WITH ANY STRONGER CELLS THAT DVLP. LOW PRES WILL LIFT NE OF AREA SUNDAY MORNING EVENTUALLY DRAGGING A COLD FRONT THRU THE AREA THRU SUN AFTN. BAND OF ASSOCIATED SHRA EXPECTED TO AFFECT THE AREA WITH THIS FEATURE THEN PUSH OFFSHORE BY EARLY EVENING. STRONG AND COLD HIGH PRES FILLS IN BEHIND THE FRONT WITH CAA PATTERN SETTING IN SUN NIGHT. TEMPS WILL BE MUCH COOLER SUN NIGHT IN THE U20S/NR30 INLAND WITH M-U30S OBX...THEN STRUGGLING TO GET OUT OF THE L40S ON MON WITH DRY WX PERSISTING AS HIGH PRES BUILDS FROM THE W. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... MON NIGHT LOOKS LIKE THE COLDEST OF THE PERIOD WITH SFC WINDS LIKELY DECOUPLING AS HIGH PRES NEARS FROM THE W. COULD BE SOME HIGH LEVEL MOISTURE FILTERING THRU AREA AROUND A BUILDING UPR RIDGE BUT DOUBT IT WILL HAVE MUCH AFFECT ON TEMPS DROPPING INTO THE L-M20S INLAND GIVEN WE AREN`T EXPECTING HIGHS TO GET MUCH PAST 40 ON MON. DRY AND COOL WX ON TAP FOR TUE AS DEEP HIGH PRES BUILDS OVER THE AREA W/ HIGHS IN THE U40S/L50S. GFS SHOWING A WEAK COASTAL TROF AND ASSOCIATED MOISTURE PUSHING INLAND TUE EVENING BUT NOT BUYING OFF ON THIS JUST YET...BUT SOMETHING TO WATCH NEXT COUPLE DAYS. HIGH PRES SLIDES OFFSHORE WED IN ADVANCE OF NEXT FRONT PUTTING US IN THE WARM SECTOR WITH HIGHS EXPECTED TO CLIMB INTO L-M60S. KEPT LOW CHANCE OF -SHRA WED AFTN/EVENING BUT MODELS NOT SHOWING SIGNIFICANT MOISTURE AT THIS POINT. FRONT EXPECTED TO MOVE INTO AREA ON CHRISTMAS DAY AND THERE REMAIN DIFFERENCES IN THE GFS/ECMWF WITH HOW FAR S THE FRONT WILL MAKE IT. GIVEN UNCERTAINTY KEPT POPS IN THE SILENT SCHC VARIETY FOR NOW. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... TAF SITES COULD SEE BRIEF PERIOD OF IFR CIGS OR VSBYS AS WINDS DIMINISH NEAR SUNRISE...OTRW VFR WILL CONTINUE THROUGH MORNING. MVFR CIGS EXPECTED TO DEVELOP THIS AFTN AS SFC WINDS BECOME NE BEHIND COLD FRONT PUSHING S ACROSS AREA. WDSPRD IFR DEVELOPING THIS EVENING AND CONTINUING OVERNIGHT AS OVERRUNNING PCPN DEVELOPES OVER LOW LVL NE FLOW. FRONTAL BNDRY WILL RETURN N AS A WARM FRONT SUN MORNING...THEN STRONG COLD FRONT WILL PUSH THROUGH BY SUN EVENING. CONDITIONS SHOULD IMPROVE TO MVFR EARLY SUNDAY AFTERNOON WITH A FEW SHOWERS POSSIBLE AS THE FRONT CROSSES THE AREA. VFR CONDITIONS SHOULD RETURN TO THE AREA LATE SUNDAY AFTERNOON AND PERSIST INTO EARLY NEXT WEEK AS A MUCH COOLER/DRIER AND MORE STABLE AIRMASS ASSOCIATED WITH CANADIAN HIGH PRESSURE BUILDING OVER THE EAST OVERSPREADS EASTERN NC. && .MARINE... CONTINUED SCA FOR COASTAL WATERS EARLY THIS MORNING MAINLY DUE TO RESIDUAL 6-7 FT SEAS...ALTHOUGH STILL SOME GUSTY WINDS OVER WARMER OUTER WATERS WITH DIAMOND BUOY UP TO 25 KTS. WINDS AND SEAS WILL DIMINISH AS PRES GRAD SLACKENS WITH FRONT MOVING IN FROM N. SOME NE LOW LVL CAA SURGE EXPECTED TO AFFECT NRN AND CENTRAL WATERS THIS AFTN BUT SPEEDS MAINLY 20 KTS OR LESS. SCA CONDITIONS LIKELY AGAIN ALL WATERS LATE TONIGHT INTO SUN AS SFC LOW MOVES ACROSS NC/VA. GALES PSBL OVER WARMER PORTIONS OF CENTRAL AND SRN WATERS SUN AFTN BUT WILL LET DAY SHIFT TAKE A LOOK. MODERATE TO STRONG CAA BEHIND COLD FRONT WILL EXTEND SCA CONDITIONS SUN NIGHT INTO MON NIGHT. CONDITIONS IMPROVING TUE WITH SFC HIGH BUILDING IN...THEN WINDS AND SEAS INCREASING AGAIN WED WITH HIGH PRES MOVING OFFSHORE AND NEXT FRONT APPROACHING. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR AMZ150- 152-154-156-158. && $$ SYNOPSIS...MW NEAR TERM...MW SHORT TERM...MW LONG TERM...MW AVIATION...JBM MARINE...JBM nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BISMARCK ND 1201 PM CST SAT DEC 20 2008 .UPDATE... WHAT A MORNING. WIND CHILLS ARE EXPECTED TO REMAIN STEADY OR FALL OVER THE NEXT 24 HOURS. MEANWHILE...ACCUMULATING SNOW HAS MOVED EAST LEAVING GUSTY NORTHWESTERLY WINDS TO PICK UP THE LOW-DENSITY SNOW THAT FELL FRIDAY THROUGH SATURDAY MORNING AND CAUSE TRAVEL DIFFICULTIES AS BLOWING AND DRIFTING SNOW REDUCES VISIBILITIES. GETTING RELIABLE OBSERVATIONS OF VISIBILITY IS RATHER DIFFICULT ON A WEEKEND MORNING...SO HAVE TO ASSUME THAT THE FEW REPORTS RECEIVED ARE REPRESENTATIVE OF THE ENTIRE AREA. CONSEQUENTLY...HAVE REPLACED WINTER STORM WARNING WITH A WINTER WEATHER ADVISORY AND HIGHLIGHTED THE DANGEROUS WIND CHILLS ALONG WITH BLOWING AND DRIFTING SNOW. ALSO EXTENDED IT THROUGH NOON CST ON SUNDAY...SINCE A SECONDARY PUSH OF ARCTIC AIR JUST NORTH OF THE BORDER IS EXPECTED TO DROP SOUTH ACROSS THE STATE LATER TODAY. THAT WILL LIKELY KEEP WINDS UP AND CONTINUE BLOWING SNOW ALONG WITH WIND CHILLS TO 50 BELOW. OUT WEST...HAVE CONTINUED THE WIND CHILL WARNING AND HIGHLIGHTED THE SAME BLOWING AND DRIFTING SNOW. DICKINSON HAS BEEN REPORTING 1 3/4 TO 4 MILES VISIBILITY WITH BLOWING SNOW...BUT SO HAS BISMARCK...AND A LOOK OUTSIDE SUGGESTS THAT ASOS IS HAVING DIFFICULTY WITH ICE CRYSTALS IN ITS SENSOR. FOR TEMPERATURES...CLOUD FORECASTS ARE WAY OFF SO FAR TODAY. THIS MEANS THAT THERE IS A GOOD CHANCE TONIGHTS CLOUD COVER WILL BE LESS THAN FORECAST. OVERALL...THAT WOULD SUGGEST THAT CONDITIONS FOR RADIATION WILL BE BETTER THAN PREVIOUSLY THOUGHT...SO ADJUSTED TEMPERATURES TO BETTER MATCH THOSE OF THE 15 UTC RUC...WHICH IS COOLER. && .PREV DISCUSSION... /ISSUED 300 AM CST SAT DEC 20 2008/ SHORT TERM...TODAY THROUGH MONDAY NIGHT... CONCERNS IN THE SHORT TERM REVOLVE AROUND DANGEROUS WIND CHILL TEMPERATURES TODAY THROUGH SUNDAY MORNING...THE CURRENT WINTER STORM CONTINUING OVER EAST CENTRAL NORTH DAKOTA...AND GETTING READY FOR THE NEXT ROUND OF POTENTIAL SIGNIFICANT SNOWS SLATED FOR MONDAY NIGHT INTO TUESDAY. FIRST AND FOREMOST...HAVE DECIDED TO CANCEL THE WINTER WEATHER ADVISORIES OVER WESTERN AND PORTIONS OF CENTRAL NORTH DAKOTA...AND IN ITS WAKE A WIND CHILL ADVISORY HAS BEEN ISSUED THROUGH 18Z SUNDAY. AT SOME POINT LATER TODAY...THE WIND CHILL ADVISORY WILL LIKELY BE UPGRADED TO A WIND CHILL WARNING...ESPECIALLY FOR THE OVERNIGHT PERIOD INTO SUNDAY MORNING AS WIND CHILL TEMPERATURES FALL TO BETWEEN 40 AND 50 BELOW ZERO...IN COMMUNITIES LIKE WILLISTON AND GARRISON. BORDERLINE WIND CHILL WARNING CRITERIA OVER MANY OTHER AREAS AND WILL LET THE DAY SHIFT SORT THIS OUT AND UPGRADE TO WARNINGS WHERE APPROPRIATE FOR LATER TODAY/TONIGHT. DESPITE BLOWING AND DRIFTING SNOW OVER THE CWA TODAY...VISIBILITIES WILL REMAIN HIGH ENOUGH AND NOT CROSS INTO ADVISORY CRITERIA...THUS DIDN`T WANT TO CONTINUE THE ADVISORY ESPECIALLY SINCE THE MAJORITY OF FALLING SNOW HAS ENDED OVER WESTERN AND MOST OF CENTRAL NORTH DAKOTA. THE MAIN HAZARD AND THREAT WILL REST SOLELY ON THE DANGEROUS WIND CHILL TEMPERATURES FROM NOW THROUGH 18Z SUNDAY. HOWEVER...FOR OUR EAST CENTRAL ZONES...FROM BOTTINEAU SOUTH TO JAMESTOWN AND ASHLEY...THE SNOW WILL CONTINUE THIS MORNING AND TAPER OFF THIS AFTERNOON. WILL LET THE WINTER STORM WARNING CONTINUE OVER THESE ZONES TODAY...BUT FULLY EXPECT THAT LATER TODAY OR EARLY TONIGHT ONCE THE SNOW ENDS AND VISIBILITIES IMPROVE ABOVE A MILE...THE WINTER STORM WILL BE CANCELED AND A WIND CHILL ADVISORY OR WARNING WILL BE ISSUED. AGAIN WILL DEFER THIS ACTION TO LATER SHIFTS. A BRIEF/24 HOUR RESPITE COMMENCES FROM SUNDAY AFTERNOON INTO MONDAY AFTERNOON...THEN ALL ATTENTION TURNS TO THE NEXT PACIFIC LOW/TROUGH TO PROGRESS INTO NORTH DAKOTA MONDAY NIGHT. GOOD CONTINUITY AND AGREEMENT CONTINUES BETWEEN THE GFS AND ECMWF WITH THIS SYSTEM...THUS HIGHER THAN AVERAGE CONFIDENCE THIS FAR OUT. HAVE RAISED POPS INTO THE HIGH CHANCE CATEGORY...AND ALL INDICATIONS ARE THAT SNOW ACCUMULATIONS WOULD LIKELY BE IN THE WINTER WEATHER ADVISORY RANGE. WILL ISSUE A SPECIAL WEATHER STATEMENT/SPS HIGHLIGHTING THIS STORM POTENTIAL AND ALSO WHAT TO EXPECT INTO CHRISTMAS...ANTICIPATING THE HIGH TRAVEL VOLUME ALL NEXT WEEK. WILL MAKE MENTION OF THIS IN THE HWO AS WELL. THIS SYSTEM EXEMPLIFIES THE PREVIOUS SNOW STORM WITH ANOTHER INVERTED SURFACE TROUGH TYPE SYSTEM AND SOUTHWEST FLOW/MOISTURE ALONG WITH STRONG WARM AIR ADVECTION PRECIPITATION OUT AHEAD OF IT...THEN COLDER BEHIND IT BUT NOT AS COLD AS PREVIOUS SYSTEMS. EXPECTING SOME LIGHT SNOW TO DEVELOP BY MID/LATE MONDAY AFTERNOON IN WESTERN AND CENTRAL NORTH DAKOTA WITH THE STEADY SNOW COMING MONDAY NIGHT THROUGH TUESDAY MORNING. ALTHOUGH THE START TIME OF WARM ADVECTION PRECIPITATION EVENTS ARE SOMETIMES DIFFICULT...AT LEAST RIGHT NOW THIS IS WHEN IT LOOKS LIKE THE SNOW WOULD INITIATE. BRISK NORTHWEST WINDS LOOK TO ARRIVE AFTER THE MAJORITY OF THE SNOW FALLS. LONG TERM...TUESDAY THROUGH SATURDAY NIGHT THE WEATHER TUESDAY WILL FEATURE CONTINUING SNOWFALL AND GUSTY NORTH WINDS AS THE SURFACE LOW TRAVELS FROM CENTRAL NORTH DAKOTA TO CENTRAL MINNESOTA. THEN HIGH PRESSURE AND UPPER LEVEL RIDGING WILL BRING A RESPITE FROM THE STORMY WINTER WEATHER OF LATE. THE NEXT POTENTIAL FOR SNOW COMES FRIDAY AND SATURDAY AS A COLORADO LOW MOVES ACROSS THE CENTRAL PLAINS BENEATH A LARGE LONG WAVE TROUGH. AVIATION... GUSTY SURFACE WINDS...SNOW SHOWERS AND BLOWING SNOW WILL PRESENT AVIATION HAZARDS TODAY AS A LOW PRESSURE CENTER EXITS THE STATE. EXPECT BRIEF IFR VISIBILITIES IN BLOWING SNOW IN SOME FAVORED AREAS && .BIS WATCHES/WARNINGS/ADVISORIES... WIND CHILL WARNING UNTIL 12 PM CST /11 AM MST/ SUNDAY FOR NDZ001>003-009>011-017>021-031>035-040>046. WINTER WEATHER ADVISORY UNTIL 12 PM CST SUNDAY FOR NDZ004-005- 012-013-022-023-025-036-037-047-048-050-051. && $$ KS/RL/SCHECK nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 635 AM EST FRI DEC 19 2008 .SYNOPSIS... A VIGOROUS LOW PRESSURE SYSTEM WILL MOVE RAPIDLY EAST ACROSS THE REGION TODAY. A WEAK RIDGE OF HIGH PRESSURE WILL BUILD INTO THE LOWER GREAT LAKES AND OHIO VALLEY ON SATURDAY. LOW PRESSURE AND AN ARCTIC COLD FRONT WILL BRING MUCH COLDER TEMPERATURES TO THE REGION FOR THE BEGINNING OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... HAVE USED A BLEND OF THE LATEST RUC AND THE NAM-WRF DUE TO THEIR HANDLING OF THE MESOSCALE FEATURES. DEEPENING SFC LOW PRESSURE OVER NW MISSOURI THIS MORNING WILL MOVE RAPIDLY EAST ACROSS ILLINOIS...INDIANA AND OHIO DURING THE REMAINDER OF THE MORNING AND EARLY AFTERNOON HOURS. THIS LOW WILL BE ASSOCIATED WITH A COLD FRONT THAT WILL PASS THROUGH BETWEEN 18Z AND 22Z. COLD AIR STILL REMAINS IN PLACE ACROSS THE WHITEWATER AND MIAMI VALLEYS THIS MORNING. THUS...AS STRONG...WARM...MOIST ASCENT LIFTS OVER THIS COLD AIR...FREEZING RAIN IS OCCURRING. HAVE HAD REPORTS OF ONE TENTH TO AS MUCH AS A QUARTER INCH OF ICE ACCUMULATION FROM E CNTRL INDIANA NE TO WEST CENTRAL OHIO. WILL CONTINUE WITH THE WINTER WX ADVISORY AND ICE STORM WARNING THROUGH THIS MORNING UNTIL WIND FLOW SHIFTS TO THE SOUTH...ALLOWING TEMPS TO WARM WELL ABOVE FREEZING. AN ADDITIONAL ONE TENTH TO ONE QUARTER OF AN INCH OF ICE ACCUMULATION WILL BE POSSIBLE. THE PCPN MAY BE LOCALLY HEAVY AT TIMES...AND THERE IS EVEN THE THREAT OF AN ISOLATED THUNDERSTORM AS ELEVATED INSTABILITY MOVES ACRS THE REGION. BY EARLY THIS AFTN...TEMPS WILL WARM APPRECIABLY OUT AHEAD OF AFOREMENTIONED COLD FRONT. HIGHS WILL RANGE FROM THE MID 30S NW TO NEAR 60 SE. PCPN WILL QUICKLY DWINDLE IN COVERAGE BY AFTN AS THE MAIN BULK OF RAIN WILL BE ASSOCIATED WITH THE DEPARTING LOW LEVEL JET. WITH A STRONG SFC PRESSURE GRADIENT AND CAA BEHIND THE COLD FRONT...SOME MODELS ARE INDICATING WIND GUSTS TO NEAR 40 KNOTS...WHICH IS WIND ADVISORY CRITERIA. HAVE KEPT WINDS JUST SHY OF THIS...AROUND 35 KNOTS...BUT DAY SHIFT WILL HAVE TO WATCH AND POSSIBLY ISSUE A WIND ADVISORY FOR A PORTION OF THE AREA IF IT BECOMES APPARENT THAT GUSTY WINDS WILL EXCEED 40 KNOTS. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... A WEAK RIDGE OF HIGH PRESSURE IS FORECAST TO BUILD INTO THE REGION LATE TONIGHT AND SATURDAY. DESPITE THE HIGH...NOT MUCH IN THE WAY OF CLEARING IS EXPECTED AS SHORT RANGE MODELS INDICATE PLENTY OF LOW LVL MOISTURE BENEATH A SUBSIDENCE INVERSION...SIMILAR TO WHAT HAPPENED THE LAST COUPLE OF DAYS THIS WEEK. AS A RESULT...HAVE COOLED TEMPS ON SATURDAY FROM THE PREVIOUS FCST...RANGING FROM AROUND 30 NORTH TO THE LOWER 40S SOUTH. FOR SATURDAY NIGHT INTO SUNDAY...MODELS ARE STILL HAVING A TOUGH TIME DEALING WITH DIGGING ENERGY INTO THE GREAT LAKES REGION AND SUBSEQUENT SFC LOW PRESSURE. THE TRACK OF THE DEVELOPING SFC LOW WILL HAVE AN IMPORTANT PART IN TERMS OF PCPN TYPE. FOR NOW...HAVE KEPT THE THREAT FOR A WINTRY MIX OF PCPN ACRS THE NRN TWO THIRDS OF THE CWFA...WITH RAIN EXPECTED ACRS THE SRN THIRD. ONCE AFOREMENTIONED SFC LOW PASSES BY TO THE ENE...AN ARCTIC FRONT IS POISED TO BLAST SE ACRS THE REGION. THIS WILL RESULT IN FALLING TEMPERATURES ON SUNDAY ALONG WITH A SMALL CHANCE FOR SOME SNOW SHOWERS. WINDS WILL BECOMING BRISK WITH GUSTS APPROACHING 40 MPH. TEMPS ARE EXPECTED TO DROP INTO THE 5 TO 10 RANGE BY MONDAY MORNING. HIGHS ON MONDAY WILL ONLY WARM INTO THE MID TEENS TO LOWER 20S AS THE ARCTIC AIRMASS WILL BE FIRMLY IN PLACE. ARCTIC HIGH PRESSURE WILL MOVE ACROSS THE OHIO VALLEY BY MONDAY NIGHT...ALLOWING SKIES TO BRIEFLY CLEAR BEFORE THE NEXT WEATHER SYSTEM BY MID NEXT WEEK. DUE TO THE COLD TEMPS AND WINDS...WIND CHILLS WILL LIKELY DIP BELOW 10 BELOW ACROSS THE REGION...WHICH MAY REQUIRE WIND CHILL ADVISORIES IN LATER FORECAST. && .LONG TERM /TUESDAY THROUGH THURSDAY/... TEMPERATURES WILL REMAIN WELL BELOW NORMAL TUESDAY AS HIGH PRESSURE MOVES EAST OF THE REGION. YET ANOTHER SOUTHERN SYSTEM APPROACHES FOR LATE TUESDAY NIGHT INTO WEDNESDAY...ALTHOUGH THERE IS QUITE A DIFFERENCE WITH POSITION AND TIMING...AND THEREFORE RESULTANT PCPN TYPES. AREAS NEAR AND SOUTH OF THE OHIO RIVER COULD SEE A RAIN/SNOW MIX. WITH THE CURRENT MODEL RUNS...HIGH PRESSURE BUILDS FOR CHRISTMAS DAY. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... THE ICING THREAT IS OVER FOR THE NORTHERN TERMINALS AS THE 32 DEGREE LINE IS JUST NORTH OF INTERSTATE 70. BOTH KDAY AND KCMH ARE REPORTING RAIN AS OF 11Z. WARMER AIR WILL CONTINUE TO FUNNEL INTO FCST AREA AHEAD OF A COLD FRONT KEEPING PCPN ALL RAIN AT THE TERMINALS. LARGE AREA OF MODERATE TO HEAVY RAIN AHEAD OF PREFRNTL TROF WILL AFFECT ALL OF THE TERMINALS THRU 15Z WITH VLIFR CONDITIONS. DRIER MID LVL AIR WILL ADVECT INTO THE FCST AREA IN WAKE OF THE PASSAGE OF THE TROF BY LATE MRNG...RESULTING IN PCPN COVERAGE DECREASING...CIGS LIFTING TO NEAR 1000FT AND E/SE WINDS VEERING TO SW. COLD FRONT WILL APPCH KDAY/KCVG/KLUK BY 18-19Z AND KILN/KCMH/KLCK BTWN 19-20Z. WINDS WILL VEER FURTHER TO WESTERLY AND BECOME GUSTY WITH STRONG 850 LLJ OVERHEAD. SOME GUSTS MAY APPCH 35-40KTS FOR A FEW HOURS DURING THE SECOND HALF OF THE AFTN. A LAGGING SFC TROF WILL PASS THRU DURING THE ERLY EVNG AND MAY SPARK A FEW SPRINKLES OR SOME DRIZZLE. WINDS WILL BECOME NRLY IN WAKE OF THIS TROF. LO LVL MOISTURE WILL REMAIN TRAPPED BENEATH A STRENGTHENING INVERSION OVERNIGHT...AND THIS WILL KEEP MVFR SC DECK IN PLACE ACRS THE REGION INTO SAT MRNG. MODEL SOUNDINGS INDCG POTENTIAL FOR POCKETS OF -DZ OR -FZDZ TOWARDS DAYBREAK SAT AS DRIER AIR DEEPENS ABV THE INVERSION. LATER FCSTS MAY NEED TO CONSIDER THIS POSSIBILITY. OUTLOOK...MVFR CIGS EXPECTED TO PERSIST INTO SATURDAY. MVFR CIGS/VSBYS CONTINUE SATURDAY NIGHT THROUGH MONDAY WITH RAIN AND SNOW SHOWERS. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...WINTER WEATHER ADVISORY UNTIL 8 AM EST THIS MORNING FOR OHZ045- 046-051>053-060-061. ICE STORM WARNING UNTIL 10 AM EST THIS MORNING FOR OHZ026-034- 035-042>044. KY...NONE. IN...WINTER WEATHER ADVISORY UNTIL 8 AM EST THIS MORNING FOR INZ050- 058-059. && $$ SYNOPSIS...HICKMAN NEAR TERM...HICKMAN SHORT TERM...HICKMAN LONG TERM... AVIATION...RYAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 1244 AM EST FRI DEC 19 2008 .SYNOPSIS... LOW PRESSURE TRAVELING ALONG A FRONTAL ZONE WILL PROVIDE MOISTURE TONIGHT AND SATURDAY. AFTER A BRIEF PERIOD OF HIGH PRESSURE ON FRIDAY NIGHT...ANOTHER LOW WILL BRING A RETURN TO MOIST AND UNSETTLED WEATHER FOR SATURDAY AND SUNDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... LATEST RUC AND NAM HOLD OUR NORTHERN COUNTIES BELOW FREEZING UNTIL 12-15Z...WHILE PRODUCING OVER A HALF INCH OF QPF. WITH TEMPS HOLDING IN THE MID TO UPPER 20S ACROSS THIS AREA...IT SEEMS LIKELY THAT THEY WILL REMAIN BELOW FREEZING WHEN THE HEAVIER PRECIP MOVES IN LATE TONIGHT. THEREFORE WILL UPGRADE THE NORTHERN MIAMI VALLEY TO AN ICE STORM WARNING...WITH AROUND A QUARTER OF AN INCH OF ICE ACCUM EXPECTED. PREVIOUS AFD FOLLOWS... ELEVATED FRONT LIFTING THROUGH THE REGION IS BRINGING AN EXPANDING BAND OF PRECIP ALONG AND NORTH OF THE I-64 CORRIDOR...AND IS JUST ABOUT TO NUDGE INTO THE FAR SW CORNER OF THE CWA. WEAK RIDGING AT THE SFC HAS BROUGHT WINDS DOWN TO NEARLY CALM...HALTING ANY CHANCE FOR WARM AIR ADVECTION OVER THE NEXT FEW HOURS. DO NOT SEE ANY CHANCE FOR REBOUNDING TEMPS UNTIL THIS RIDGE MOVES EAST OF HERE AND DECENT SOUTHEASTERLY FLOW CAN BECOME ESTABLISHED. LATEST RUC INDICATES THIS MAY NOT HAPPEN UNTIL WELL AFTER MIDNIGHT...SO TEMPS UNTIL THIS TIME SHOULD STAY ROUGHLY WHERE THEY`RE AT. WITH PRECIP COMING IN SLIGHTLY FASTER THAN ANTICIPATED...DECIDED TO EXPAND THE WINTER WX ADVISORY TO AREAS WHERE TEMPS ARE CURRENTLY BELOW FREEZING. MOST OF THIS PRECIP WILL BE VERY LIGHT...AS BULK OF THE FORCING IS NOT EXPECTED TO ARRIVE UNTIL AFTER 06Z. THEREFORE JUST A THIN GLAZING OF ICE IS EXPECTED...BUT EVEN THIS MAY BE ENOUGH TO CAUSE TRAVEL PROBLEMS. TOOK THE ADVY UNTIL 4 AM...WHEN IT LOOKS LIKE TEMPS SHOULD FINALLY RISE ABOVE FREEZING ACROSS THE I-71 CORRIDOR. DID NOT INCLUDE THE IMMEDIATE CINCY METRO IN THE ADVY AS MOST SENSORS AROUND HAMILTON COUNTY ARE ABOVE FREEZING. DID NOT GO AS FAR EAST AS COLUMBUS...SINCE HEAVIEST PRECIP IS NOT EXPECTED TO MAKE IT THERE UNTIL TEMPS START RISING ABOVE FREEZING. && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/... AS WARM ADVECTION AT THE SURFACE OVERSPREADS THE AREA...FREEZING RAIN WILL CHANGE TO ALL RAIN EARLY FRIDAY. AS THE LOW PROCEEDS TO PENNSYLVANIA...THE RAIN WILL DIMINISH BY MID EVENING...CHANGING TO SNOW IN THE NORTH EARLY FRIDAY NIGHT BEFORE ENDING COMPLETELY. A SHORT PERIOD OF WEAK RIDGING LATE FRIDAY NIGHT AND EARLY SATURDAY WILL BE FOLLOWED BY ANOTHER LOW. THERE WILL BE A CHANCE OF RAIN ON SATURDAY...WITH SNOW BECOMING LIKELY SATURDAY NIGHT. BASED ON GFS AGAIN...LIGHT SNOW ACCUMULATIONS WILL BE POSSIBLE. && .LONG TERM /SUNDAY THROUGH THURSDAY/... THERE ARE SOME POSITIONAL DIFFERENCES...BUT THE TREND IS FASTER WITH THE PROGRESSION OF THE LOW PRESSURE SYSTEM AND STRONG COLD FRONT. BY 12Z SUNDAY MORNING...WITH EITHER THE GFS OR ECMWF...MUCH COLDER ARCTIC AIR WILL BE WORKING IN BEHIND DEPARTING LOW PRESSURE. SCT SNOW SHOWERS WILL PERSIST SUNDAY AFTERNOON WITH VERY GUSTY WINDS...AS TEMPERATURES FALL FROM EARLY MORNING HIGHS. LOWS OVERNIGHT WILL DROP WELL INTO THE TEENS. SCT/ISO SNOW SHOWERS WILL PERSIST INTO MONDAY WITH A TRAILING UPPER DISTURBANCE. ARCTIC AIR WILL HAVE NORTHERN OHIO STRUGGLING TO REACH 20 DEGREES FOR HIGH TEMPERATURES. TEMPERATURES WILL REMAIN WELL BELOW NORMAL TUESDAY AS HIGH PRESSURE BRIEFLY BUILDS AND MOVES EAST OF THE REGION. YET ANOTHER SOUTHERN SYSTEM APPROACHES FOR LATE TUESDAY NIGHT INTO WEDNESDAY...ALTHOUGH THERE IS QUITE A DIFFERENCE WITH POSITION AND TIMING...AND THEREFORE RESULTANT PCPN TYPES. AREAS NEAR AND SOUTH OF THE OHIO RIVER COULD SEE A RAIN/SNOW MIX. WITH THE CURRENT MODEL RUNS...HIGH PRESSURE BUILDS FOR CHRISTMAS DAY. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... PCPN TYPE WITHIN THE FIRST SIX HOURS OF THE TAF FCST REMAINS THE INITIAL ISSUE FOR THIS PACKAGE. PERUSAL OF AREA SFC OBS ERLY THIS MRNG PLACES 32F LINE FROM NEAR KHAO EAST TO INTERSTATE 71...THEN FOLLOWING I-71 NORTHEAST INTO THE CMH METRO. KDAY REPORTING -RA CURRENTLY BUT SURROUNDING OBS INDCG -FZRA. WILL KEEP PREVAILING -FZRA THERE THRU 09Z AND MONITOR OBS. SHOULD WARMER SFC AIR OVERSPREAD KDAY A LITTLE FASTER THAN ANTICIPATED WILL ISSUE AN AMENDMENT. KCMH PRESENTS A SIMILAR PROBLEM AS 32F LINE APPEARS TO BISECT FRANKLIN CO ATTM. HAVE DECIDED TO GO WITH PREVAILING -RA AT KCMH BUT INDCG POTENTIAL FRO -FZRA IN A TEMPO GROUP. LO LVLS SHOULD WARM ENUF FOR ALL RAIN HERE BY 09Z AS WELL. SFC TEMPS SLIGHTLY WARMER AT KLCK AND WILL GO WITH JUST -RA HERE. INITIAL SHOT OF OVERRUNNING PCPN AHEAD OF ELEVATED WARM FRONT PROGRESSING ACRS FCST AREA ERLY THIS MRNG. PCPN AREA HAS MOVED NORTH OF KCVG/KLUK...BUT WAA PCPN REDVLPG ACRS CNTRL KY WILL MOVE BACK ACRS SW FCST AREA OVER NEXT FEW HOURS. WIDESPREAD LIFR/VLIFR CONDITIONS TO SOUTHWEST ACRS LWR OH VLY AND HAVE THUS LOWERED CIGS/VSBYS AT ALL TERMINALS THRU THE REMAINDER OF THE OVERNIGHT AND INTO THE MRNG. HEAVIER AREA OF PCPN ASSOCD WITH PREFRNTL TROF AND VERY STRONG LLJ WILL AFFECT ALL OF THE TERMINALS FOR ABOUT A 3-5 HOUR PERIOD DURING THE FIRST HALF OF THE MRNG. RAPID MID LVL DRYING IN WAKE OF THE TROF WILL SHUT THE PCPN DOWN INTO THE ERLY AFTN...AND SHOULD ALLOW CIGS TO EVENTUALLY LIFT TO JUST ABV 1000 FT. MODEL SOUNDINGS INDCG SOME GUSTS TO NEAR 30 KTS DURING THE AFTN AS COLD FRONT PUSHES THRU FCST AREA AND WINDS SWING AROUND TO WESTERLY. MAY SEE SOME SCT SPRINKLES OR DRIZZLE REDVLP BY LATE AFTN/ERLY EVNG AS LAGGING SFC TROF DROPS SOUTH THRU FCST AREA. WINDS WILL BECOME NRLY IN WAKE OF THIS TROF. THICK MVFR SC DECK WILL PERSIST THRU THE NIGHT AS LO LVL INVERSION REESTABLISHES. OUTLOOK...MVFR/IFR CIGS EXPECTED TO PERSIST INTO SATURDAY. MVFR CIGS/VSBYS WITH RAIN AND SNOW SHOWERS POSSIBLE SATURDAY NIGHT INTO MONDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...WINTER WEATHER ADVISORY UNTIL 8 AM EST THIS MORNING FOR OHZ045- 046-051>053-060-061. ICE STORM WARNING UNTIL 10 AM EST THIS MORNING FOR OHZ026-034- 035-042>044. WINTER WEATHER ADVISORY UNTIL 4 AM EST EARLY THIS MORNING FOR OHZ054-062-063-070>072. KY...NONE. IN...WINTER WEATHER ADVISORY UNTIL 8 AM EST THIS MORNING FOR INZ050- 058-059. WINTER WEATHER ADVISORY UNTIL 4 AM EST EARLY THIS MORNING FOR INZ066-073-074. && $$ SYNOPSIS...CONIGLIO NEAR TERM...HAWBLITZEL SHORT TERM...CONIGLIO LONG TERM... AVIATION...RYAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1118 AM CST SAT DEC 20 2008 .AVIATION... N WINDS CONTINUING ALL AREAS THROUGH SUNDAY MORNING BUT DECREASING IN SPEED ESPECIALLY AFTER NIGHTFALL. LOW CLOUDS AND HAZE CURRENTLY LOOKS TO BE LIMITED TO KPNC AREA THIS AFTERNOON... WHERE IT MAY BE IN AND OUT THROUGH EARLY EVENING AS COLD ADVECTION CONTINUES. OTHERWISE ONLY MID/HIGH CLOUDS. && .PREV DISCUSSION... /ISSUED 1005 AM CST SAT DEC 20 2008/ UPDATE... STRONG COLD FRONT CONT TO SWEEP SOUTH ACROSS THE AREA THIS MORNING. STRONG CAA AND NORTH WINDS WILL CAUSE FALLING TEMPS AND LOW WIND CHILLS TO BE MAIN FOCUS FOR TODAY. HAVE MADE SOME MINOR CHANGES TO HOURLY TEMP GRIDS TO TRY AND SHOW BETTER TREND FOR TODAY AND QUICKER ARRIVAL OF FRONT/CAA ACROSS THE SOUTH. 30 ---------------------------------------- 546 AM CST SAT DEC 20 2008 AVIATION... A STRONG COLD FRONT EXTENDING FROM FAR NORTHWEST OK INTO CENTRAL KS WILL MOVE QUICKLY SOUTH ACROSS THE TERMINALS TODAY. A PRE- FRONTAL TROUGH WILL SHIFT THE WINDS TO THE WNW AHEAD OF THE FRONT. BEHIND THE COLD FRONT... N-NW WINDS WILL GUST 25 TO 30 KTS TODAY... BEFORE DIMINISHING TONIGHT. THE PRIMARY FRONT WILL REACH THE GAG AND WWR TERMINALS 12-13Z... CENTRAL AND SW OK BY MIDDAY AND NORTH TX EARLY IN THE AFTERNOON. MVFR CIGS WILL BE POSSIBLE BEHIND THE FRONT IN NORTH CENTRAL OK... BECOMING SCATTERED IN CENTRAL OK. THE REMAINDER OF THE TERMINALS WILL HAVE CIGS AROUND 25K FT BECOMING SCATTERED BY EVENING. PREV DISCUSSION... /ISSUED 410 AM CST SAT DEC 20 2008/ DISCUSSION... A COLD FRONT IN NORTHWEST KANSAS EARLY THIS MORNING WILL MOVE FAIRLY QUICKLY THROUGH THE CWA TODAY. ONCE THE TRUE FRONT PASSES THROUGH AN AREA... TEMPERATURES WILL GENERALLY TREND LOWER FOR THE REMAINDER OF THE DAY. THEREFORE... THE HIGH TEMPERATURE FORECASTS WILL BE PROBLEMATIC AS THEY WILL BE DEPENDENT ON THE TIMING OF THE COLD AIR. THE NAM IS INDICATING A PRE-FRONTAL TROUGH... AND ASSOCIATED WIND SHIFT... WHICH MAY MAKE IT MORE DIFFICULT TO CLEARLY TIME THE PASSAGE OF THE TRUE FRONT. BOTH THE NAM AND RUC INDICATING THE STRONGER LOW LEVEL COLD ADVECTION REACHING SOUTHERN OKLAHOMA AROUND NOON... WITH THE PRE-FRONTAL TROUGH ALREADY WELL INTO NORTH TEXAS. THE FRONT SHOULD CLEAR THE REST OF THE CWA BY 6 PM. ALTHOUGH 60 DEGREE SURFACE DEWPOINTS ARE MOVING NORTH THROUGH EAST TEXAS... VEERING WINDS AHEAD OF COLD FRONT WILL LIKELY RESULT IN VERY SHALLOW MOISTURE IN OUR SOUTHEAST COUNTIES. THE SHALLOW MOISTURE... ALONG WITH THE FRONT`S RELATIVELY QUICK MOVEMENT... WILL KEEP RAIN CHANCES VERY SMALL IN THE SOUTHEAST PART OF THE CWA. TEMPERATURES WILL DROP INTO THE TEENS OVERNIGHT IN MOST AREAS WITH LOWER 20S IN NORTH TEXAS... WHILE EVEN COLDER READINGS ARE EXPECTED BY EARLY MONDAY MORNING WITH LOWS RANGING IN THE SINGLE DIGITS TO THE MID TEENS. INCREASING SOUTH WINDS MONDAY THROUGH TUESDAY WILL BEGIN TO MODERATE TEMPERATURES OVER THE AREA ESPECIALLY ON TUESDAY. MEANWHILE... MODELS HAVE COME INTO A BETTER AGREEMENT THIS MORNING WITH THEIR TIMING OF NEXT UPPER AIR SYSTEM AND COLD FRONT FOR TUESDAY. RAIN SHOULD BEGIN TO DEVELOP DURING THE DAY TUESDAY AS THE UPPER WAVE APPROACHES... WITH THE BEST RAIN CHANCES BEING ACROSS THE CENTRAL AND EAST. A MIX OF LIGHT WINTER PRECIPITATION WILL BE POSSIBLE ACROSS NORTHERN OKLAHOMA TUESDAY NIGHT BEHIND A COLD FRONT THAT MOVES THROUGH THE REGION. AMOUNTS ARE EXPECTED TO BE LIGHT AS THE WINDOW OF OPPORTUNITY... THAT BEING THE INTERVAL AFTER FRONTAL PASSAGE BUT BEFORE THE EXIT OF THE UPPER WAVE... APPEARS TO BE RATHER SHORT. THE AIR BEHIND THIS FRONT DOES NOT LOOK TO BE AS COLD AS THAT OF THIS WEEKEND... AND SHOULD BEGIN TO MODIFY FAIRLY QUICKLY BY WEDNESDAY NIGHT AND THURSDAY AS SOUTH TO SOUTHWEST WINDS RETURN. AT THE END OF NEXT WEEK THERE ARE SIGNIFICANT DIFFERENCES BETWEEN THE MODELS WITH THE HANDLING STORM SYSTEM FOR LATE NEXT FRIDAY. FOR NOW... WE WILL KEEP THE POPS ON THE LOW SIDE UNTIL CONFIDENCE IN THE EVOLUTION AND TIMING OF THE NEXT SYSTEM IMPROVES. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 49 16 29 13 / 0 0 0 0 HOBART OK 44 18 32 14 / 0 0 0 0 WICHITA FALLS TX 54 21 34 16 / 10 0 0 0 GAGE OK 37 11 24 8 / 0 0 0 0 PONCA CITY OK 35 14 24 7 / 0 0 0 0 DURANT OK 61 21 38 15 / 10 0 0 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 30/24/01 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1005 AM CST SAT DEC 20 2008 .UPDATE... STRONG COLD FRONT CONT TO SWEEP SOUTH ACROSS THE AREA THIS MORNING. STRONG CAA AND NORTH WINDS WILL CAUSE FALLING TEMPS AND LOW WIND CHILLS TO BE MAIN FOCUS FOR TODAY. HAVE MADE SOME MINOR CHANGES TO HOURLY TEMP GRIDS TO TRY AND SHOW BETTER TREND FOR TODAY AND QUICKER ARRIVAL OF FRONT/CAA ACROSS THE SOUTH. 30 ---------------------------------------- 546 AM CST SAT DEC 20 2008 .AVIATION... A STRONG COLD FRONT EXTENDING FROM FAR NORTHWEST OK INTO CENTRAL KS WILL MOVE QUICKLY SOUTH ACROSS THE TERMINALS TODAY. A PRE- FRONTAL TROUGH WILL SHIFT THE WINDS TO THE WNW AHEAD OF THE FRONT. BEHIND THE COLD FRONT... N-NW WINDS WILL GUST 25 TO 30 KTS TODAY... BEFORE DIMINISHING TONIGHT. THE PRIMARY FRONT WILL REACH THE GAG AND WWR TERMINALS 12-13Z... CENTRAL AND SW OK BY MIDDAY AND NORTH TX EARLY IN THE AFTERNOON. MVFR CIGS WILL BE POSSIBLE BEHIND THE FRONT IN NORTH CENTRAL OK... BECOMING SCATTERED IN CENTRAL OK. THE REMAINDER OF THE TERMINALS WILL HAVE CIGS AROUND 25K FT BECOMING SCATTERED BY EVENING. && .PREV DISCUSSION... /ISSUED 410 AM CST SAT DEC 20 2008/ DISCUSSION... A COLD FRONT IN NORTHWEST KANSAS EARLY THIS MORNING WILL MOVE FAIRLY QUICKLY THROUGH THE CWA TODAY. ONCE THE TRUE FRONT PASSES THROUGH AN AREA... TEMPERATURES WILL GENERALLY TREND LOWER FOR THE REMAINDER OF THE DAY. THEREFORE... THE HIGH TEMPERATURE FORECASTS WILL BE PROBLEMATIC AS THEY WILL BE DEPENDENT ON THE TIMING OF THE COLD AIR. THE NAM IS INDICATING A PRE-FRONTAL TROUGH... AND ASSOCIATED WIND SHIFT... WHICH MAY MAKE IT MORE DIFFICULT TO CLEARLY TIME THE PASSAGE OF THE TRUE FRONT. BOTH THE NAM AND RUC INDICATING THE STRONGER LOW LEVEL COLD ADVECTION REACHING SOUTHERN OKLAHOMA AROUND NOON... WITH THE PRE-FRONTAL TROUGH ALREADY WELL INTO NORTH TEXAS. THE FRONT SHOULD CLEAR THE REST OF THE CWA BY 6 PM. ALTHOUGH 60 DEGREE SURFACE DEWPOINTS ARE MOVING NORTH THROUGH EAST TEXAS... VEERING WINDS AHEAD OF COLD FRONT WILL LIKELY RESULT IN VERY SHALLOW MOISTURE IN OUR SOUTHEAST COUNTIES. THE SHALLOW MOISTURE... ALONG WITH THE FRONT`S RELATIVELY QUICK MOVEMENT... WILL KEEP RAIN CHANCES VERY SMALL IN THE SOUTHEAST PART OF THE CWA. TEMPERATURES WILL DROP INTO THE TEENS OVERNIGHT IN MOST AREAS WITH LOWER 20S IN NORTH TEXAS... WHILE EVEN COLDER READINGS ARE EXPECTED BY EARLY MONDAY MORNING WITH LOWS RANGING IN THE SINGLE DIGITS TO THE MID TEENS. INCREASING SOUTH WINDS MONDAY THROUGH TUESDAY WILL BEGIN TO MODERATE TEMPERATURES OVER THE AREA ESPECIALLY ON TUESDAY. MEANWHILE... MODELS HAVE COME INTO A BETTER AGREEMENT THIS MORNING WITH THEIR TIMING OF NEXT UPPER AIR SYSTEM AND COLD FRONT FOR TUESDAY. RAIN SHOULD BEGIN TO DEVELOP DURING THE DAY TUESDAY AS THE UPPER WAVE APPROACHES... WITH THE BEST RAIN CHANCES BEING ACROSS THE CENTRAL AND EAST. A MIX OF LIGHT WINTER PRECIPITATION WILL BE POSSIBLE ACROSS NORTHERN OKLAHOMA TUESDAY NIGHT BEHIND A COLD FRONT THAT MOVES THROUGH THE REGION. AMOUNTS ARE EXPECTED TO BE LIGHT AS THE WINDOW OF OPPORTUNITY... THAT BEING THE INTERVAL AFTER FRONTAL PASSAGE BUT BEFORE THE EXIT OF THE UPPER WAVE... APPEARS TO BE RATHER SHORT. THE AIR BEHIND THIS FRONT DOES NOT LOOK TO BE AS COLD AS THAT OF THIS WEEKEND... AND SHOULD BEGIN TO MODIFY FAIRLY QUICKLY BY WEDNESDAY NIGHT AND THURSDAY AS SOUTH TO SOUTHWEST WINDS RETURN. AT THE END OF NEXT WEEK THERE ARE SIGNIFICANT DIFFERENCES BETWEEN THE MODELS WITH THE HANDLING STORM SYSTEM FOR LATE NEXT FRIDAY. FOR NOW... WE WILL KEEP THE POPS ON THE LOW SIDE UNTIL CONFIDENCE IN THE EVOLUTION AND TIMING OF THE NEXT SYSTEM IMPROVES. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 50 16 29 13 / 0 0 0 0 HOBART OK 49 18 32 14 / 0 0 0 0 WICHITA FALLS TX 63 21 34 16 / 10 0 0 0 GAGE OK 43 11 24 8 / 0 0 0 0 PONCA CITY OK 36 14 24 7 / 0 0 0 0 DURANT OK 68 21 38 15 / 10 0 0 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 26/32/32 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 546 AM CST SAT DEC 20 2008 .AVIATION... A STRONG COLD FRONT EXTENDING FROM FAR NORTHWEST OK INTO CENTRAL KS WILL MOVE QUICKLY SOUTH ACROSS THE TERMINALS TODAY. A PRE- FRONTAL TROUGH WILL SHIFT THE WINDS TO THE WNW AHEAD OF THE FRONT. BEHIND THE COLD FRONT... N-NW WINDS WILL GUST 25 TO 30 KTS TODAY... BEFORE DIMINISHING TONIGHT. THE PRIMARY FRONT WILL REACH THE GAG AND WWR TERMINALS 12-13Z... CENTRAL AND SW OK BY MIDDAY AND NORTH TX EARLY IN THE AFTERNOON. MVFR CIGS WILL BE POSSIBLE BEHIND THE FRONT IN NORTH CENTRAL OK... BECOMING SCATTERED IN CENTRAL OK. THE REMAINDER OF THE TERMINALS WILL HAVE CIGS AROUND 25K FT BECOMING SCATTERED BY EVENING. && .PREV DISCUSSION... /ISSUED 410 AM CST SAT DEC 20 2008/ DISCUSSION... A COLD FRONT IN NORTHWEST KANSAS EARLY THIS MORNING WILL MOVE FAIRLY QUICKLY THROUGH THE CWA TODAY. ONCE THE TRUE FRONT PASSES THROUGH AN AREA... TEMPERATURES WILL GENERALLY TREND LOWER FOR THE REMAINDER OF THE DAY. THEREFORE... THE HIGH TEMPERATURE FORECASTS WILL BE PROBLEMATIC AS THEY WILL BE DEPENDENT ON THE TIMING OF THE COLD AIR. THE NAM IS INDICATING A PRE-FRONTAL TROUGH... AND ASSOCIATED WIND SHIFT... WHICH MAY MAKE IT MORE DIFFICULT TO CLEARLY TIME THE PASSAGE OF THE TRUE FRONT. BOTH THE NAM AND RUC INDICATING THE STRONGER LOW LEVEL COLD ADVECTION REACHING SOUTHERN OKLAHOMA AROUND NOON... WITH THE PRE-FRONTAL TROUGH ALREADY WELL INTO NORTH TEXAS. THE FRONT SHOULD CLEAR THE REST OF THE CWA BY 6 PM. ALTHOUGH 60 DEGREE SURFACE DEWPOINTS ARE MOVING NORTH THROUGH EAST TEXAS... VEERING WINDS AHEAD OF COLD FRONT WILL LIKELY RESULT IN VERY SHALLOW MOISTURE IN OUR SOUTHEAST COUNTIES. THE SHALLOW MOISTURE... ALONG WITH THE FRONT`S RELATIVELY QUICK MOVEMENT... WILL KEEP RAIN CHANCES VERY SMALL IN THE SOUTHEAST PART OF THE CWA. TEMPERATURES WILL DROP INTO THE TEENS OVERNIGHT IN MOST AREAS WITH LOWER 20S IN NORTH TEXAS... WHILE EVEN COLDER READINGS ARE EXPECTED BY EARLY MONDAY MORNING WITH LOWS RANGING IN THE SINGLE DIGITS TO THE MID TEENS. INCREASING SOUTH WINDS MONDAY THROUGH TUESDAY WILL BEGIN TO MODERATE TEMPERATURES OVER THE AREA ESPECIALLY ON TUESDAY. MEANWHILE... MODELS HAVE COME INTO A BETTER AGREEMENT THIS MORNING WITH THEIR TIMING OF NEXT UPPER AIR SYSTEM AND COLD FRONT FOR TUESDAY. RAIN SHOULD BEGIN TO DEVELOP DURING THE DAY TUESDAY AS THE UPPER WAVE APPROACHES... WITH THE BEST RAIN CHANCES BEING ACROSS THE CENTRAL AND EAST. A MIX OF LIGHT WINTER PRECIPITATION WILL BE POSSIBLE ACROSS NORTHERN OKLAHOMA TUESDAY NIGHT BEHIND A COLD FRONT THAT MOVES THROUGH THE REGION. AMOUNTS ARE EXPECTED TO BE LIGHT AS THE WINDOW OF OPPORTUNITY... THAT BEING THE INTERVAL AFTER FRONTAL PASSAGE BUT BEFORE THE EXIT OF THE UPPER WAVE... APPEARS TO BE RATHER SHORT. THE AIR BEHIND THIS FRONT DOES NOT LOOK TO BE AS COLD AS THAT OF THIS WEEKEND... AND SHOULD BEGIN TO MODIFY FAIRLY QUICKLY BY WEDNESDAY NIGHT AND THURSDAY AS SOUTH TO SOUTHWEST WINDS RETURN. AT THE END OF NEXT WEEK THERE ARE SIGNIFICANT DIFFERENCES BETWEEN THE MODELS WITH THE HANDLING STORM SYSTEM FOR LATE NEXT FRIDAY. FOR NOW... WE WILL KEEP THE POPS ON THE LOW SIDE UNTIL CONFIDENCE IN THE EVOLUTION AND TIMING OF THE NEXT SYSTEM IMPROVES. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 50 16 29 13 / 0 0 0 0 HOBART OK 49 18 32 14 / 0 0 0 0 WICHITA FALLS TX 63 21 34 16 / 10 0 0 0 GAGE OK 43 11 24 8 / 0 0 0 0 PONCA CITY OK 36 14 24 7 / 0 0 0 0 DURANT OK 68 21 38 15 / 10 0 0 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 26/32/32 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 410 AM CST SAT DEC 20 2008 .DISCUSSION... A COLD FRONT IN NORTHWEST KANSAS EARLY THIS MORNING WILL MOVE FAIRLY QUICKLY THROUGH THE CWA TODAY. ONCE THE TRUE FRONT PASSES THROUGH AN AREA... TEMPERATURES WILL GENERALLY TREND LOWER FOR THE REMAINDER OF THE DAY. THEREFORE... THE HIGH TEMPERATURE FORECASTS WILL BE PROBLEMATIC AS THEY WILL BE DEPENDENT ON THE TIMING OF THE COLD AIR. THE NAM IS INDICATING A PRE-FRONTAL TROUGH... AND ASSOCIATED WIND SHIFT... WHICH MAY MAKE IT MORE DIFFICULT TO CLEARLY TIME THE PASSAGE OF THE TRUE FRONT. BOTH THE NAM AND RUC INDICATING THE STRONGER LOW LEVEL COLD ADVECTION REACHING SOUTHERN OKLAHOMA AROUND NOON... WITH THE PRE-FRONTAL TROUGH ALREADY WELL INTO NORTH TEXAS. THE FRONT SHOULD CLEAR THE REST OF THE CWA BY 6 PM. ALTHOUGH 60 DEGREE SURFACE DEWPOINTS ARE MOVING NORTH THROUGH EAST TEXAS... VEERING WINDS AHEAD OF COLD FRONT WILL LIKELY RESULT IN VERY SHALLOW MOISTURE IN OUR SOUTHEAST COUNTIES. THE SHALLOW MOISTURE... ALONG WITH THE FRONT`S RELATIVELY QUICK MOVEMENT... WILL KEEP RAIN CHANCES VERY SMALL IN THE SOUTHEAST PART OF THE CWA. TEMPERATURES WILL DROP INTO THE TEENS OVERNIGHT IN MOST AREAS WITH LOWER 20S IN NORTH TEXAS... WHILE EVEN COLDER READINGS ARE EXPECTED BY EARLY MONDAY MORNING WITH LOWS RANGING IN THE SINGLE DIGITS TO THE MID TEENS. INCREASING SOUTH WINDS MONDAY THROUGH TUESDAY WILL BEGIN TO MODERATE TEMPERATURES OVER THE AREA ESPECIALLY ON TUESDAY. MEANWHILE... MODELS HAVE COME INTO A BETTER AGREEMENT THIS MORNING WITH THEIR TIMING OF NEXT UPPER AIR SYSTEM AND COLD FRONT FOR TUESDAY. RAIN SHOULD BEGIN TO DEVELOP DURING THE DAY TUESDAY AS THE UPPER WAVE APPROACHES... WITH THE BEST RAIN CHANCES BEING ACROSS THE CENTRAL AND EAST. A MIX OF LIGHT WINTER PRECIPITATION WILL BE POSSIBLE ACROSS NORTHERN OKLAHOMA TUESDAY NIGHT BEHIND A COLD FRONT THAT MOVES THROUGH THE REGION. AMOUNTS ARE EXPECTED TO BE LIGHT AS THE WINDOW OF OPPORTUNITY... THAT BEING THE INTERVAL AFTER FRONTAL PASSAGE BUT BEFORE THE EXIT OF THE UPPER WAVE... APPEARS TO BE RATHER SHORT. THE AIR BEHIND THIS FRONT DOES NOT LOOK TO BE AS COLD AS THAT OF THIS WEEKEND... AND SHOULD BEGIN TO MODIFY FAIRLY QUICKLY BY WEDNESDAY NIGHT AND THURSDAY AS SOUTH TO SOUTHWEST WINDS RETURN. AT THE END OF NEXT WEEK THERE ARE SIGNIFICANT DIFFERENCES BETWEEN THE MODELS WITH THE HANDLING STORM SYSTEM FOR LATE NEXT FRIDAY. FOR NOW... WE WILL KEEP THE POPS ON THE LOW SIDE UNTIL CONFIDENCE IN THE EVOLUTION AND TIMING OF THE NEXT SYSTEM IMPROVES. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 50 16 29 13 / 0 0 0 0 HOBART OK 49 18 32 14 / 0 0 0 0 WICHITA FALLS TX 63 21 34 16 / 10 0 0 0 GAGE OK 43 11 24 8 / 0 0 0 0 PONCA CITY OK 36 14 24 7 / 0 0 0 0 DURANT OK 68 21 38 15 / 10 0 0 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 26/32 ok AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 1229 PM CST SAT DEC 20 2008 .UPDATE... HERE IS THE SECOND UPDATE TODAY TO UPDATE HEADLINES. HAVE DROPPED BROWN AND SPINK COUNTIES INTO A WIND CHILL WARNING ALONG WITH THE REST OF CENTRAL AND NORTH CENTRAL SOUTH DAKOTA FROM NOW UNTIL 18Z SUNDAY. SNOW IS VACATING THE VERY EASTERN EDGE OF THE FORECAST AREA AT THIS TIME. REPORTS HAVE CONTINUED TO STREAM IN THIS MORNING OF BLIZZARD CONDITIONS ONGOING ACROSS THE FART EASTERN FORECAST ZONES...INCLUDING THE I-29 CORRIDOR. SO...FROM MARSHALL AND DAY AND CLARK COUNTIES AND POINTS EAST...WHERE THE MOST SNOW HAS FALLEN IN THE PAST 24 HOURS...HAVE CONTINUED THE BLIZZARD WARNING THROUGH TONIGHT...AND THEN TACKED ON A WIND CHILL WARNING AT THE TAIL END OF THINGS FROM 12Z SUNDAY THROUGH 18Z SUNDAY TO MATCH UP WITH THE OTHER WIND CHILL WARNING HEADLINE. ONCE VISIBILITY RESTRICTIONS IMPROVE OUT EAST TO BETTER THAN ONE QUARTER MILE...THE BLIZZARD WARNING CAN BE TAKEN DOWN AND THE WIND CHILL WARNING CAN SIMPLY FILL IN TO TAKE THE PLACE OF THE BLIZZARD WARNING. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH MONDAY. MAIN FCST CHALLENGE FACING THE NEAR TERM DEALS WITH ONGOING PCPN AND BLIZZARD POTENTIAL...AND TEMPS FOR THE REST OF THE WEEKEND. LATEST MSAS ANLYS SHOWS INVERTED SFC TROF NOW JUST EAST OF THE JAMES RIVER VALLEY...WITH SFC WINDS NW BEHIND THIS FEATURE. WINDS ARE BEGINNING TO INCREASE OUT BY THE MO RIVER...WITH KMBG GUSTING TO 30MPH AND KPIR HAVING A PEAK WIND TO 36 MPH. NAM/GFS AGREE THAT MAIN AREA OF FORCING WILL SLIP THROUGH THE ERN PART OF THE CWA BY 12Z...AND MOVE INTO MN BY 15Z. THIS COINCIDES NICELY WITH MAIN AREA OF 7H THETA-E FORCING ALSO SLIDING EAST OF THE CWA BY 15Z...WITH DOWNGLIDE THEN MOVING IN THEREAFTER. WITH BUFKIT SHOWING DECENT OMEGA LIFTING THROUGH SNOWGROWTH AREA...SHOULD BE ABLE TO SQUEEZE OUT 2-3 INCHES OF LIGHT FLUFFY SNOW PRIOR TO WINDS SHOWING UP. WHICH...IF IT WEREN`T FOR THE WIND POTENTIAL...BLIZZARD WARNING COULD MOST LIKELY BE LOWERED TO A SNOW/BS ADVRY. HOWEVER...LATEST RUC IS SHOWING 925MB GEOSTROPHIC WINDS ON THE ORDER OF 30 TO 40 KTS...AND GIVEN CURRENT GUSTS SETTING UP ACROSS THE MO RIVER AREA...THINK THAT VSBYS WILL BEGIN TO DIMINISH RAPIDLY AS THE WINDS HIT THE POWDER ACROSS THE BLIZZARD WARNING AREA. HAVE INCLUDED SPINK COUNTY IN THE BLIZZARD WARNING AS CALL PLACED TO LAW ENFORCEMENT CONFIRMS 1.5" OF NEW SNOW WITH VSBYS LOWERING ACROSS THE WESTERN SECTIONS OF THE COUNTY DUE TO BLSN. FURTHER WEST...SNOW AMOUNTS SHOULD BE DRAMATICALLY LESS...SO WILL LET THE WINTER WEATHER ADVRY RIDE FOR SNOW/BLSN. TIMING THE END OF THE HEADLINE WILL BE AN ISSUE. DEFINITE BACK EDGE OF SNOW CAN BE SEEN ON KABR 88D...BUT PERSISTANT STRONG WINDS WILL DETERIME LENGTH OF HEADLINE. FOR NOW...HAVE OPTED TO KEEP HEADLINE EXPIRATION TIME AS INHERITED JUST TO KEEP THINGS SIMPLE AND CONSISTENT...ALTHOUGH FEEL IT MAY BE A BIT LONG WHEN LOOKING AT SNOW PRODUCTION TIMING. AS DOWNGLIDE SWEEPS EAST ACROSS THE CWA...EXPECT THE SNOW TO END RATHER RAPIDLY DURING THE DAY...WITH BLSN BEING THE MAIN WEATHER FACTOR. HAVE DECREASED POPS QUICKER THAN INHERITED...BUT KEPT MENTION OF BLSN GOING. WITH STRONG CAA SWEEPING IN...HAVE ALSO CONTINUED TREND OF FALLING TEMPS THROUGH THE DAY. 7H CLOSED LOW SWEEPS SOUTH AND EAST OF THE AREA THROUGH 12Z SUNDAY...WITH BACKDOOR 7H TROF DROPPING THROUGH THE EAST. MAY PROVIDE JUST ENOUGH FOCUS FOR LIGHT SNOW/FLURRIES TO REDEVELOP DURING THE LATE MORNING THROUGH THE AFTERNOON ON SUNDAY...BUT LITTLE IF ANY ADDITIONAL ACCUMULATIONS EXPECTED. THEN COMES THE COLD. NAM CONTS TO SHOW 1035MB ARCTIC HIGH DROPPING INTO THE MIDWEST AND SETTING UP SHOP. COND PRESSURE DEFICITS SHOW THAT CLOUDS SHOULD ERODE/MOVE OUT OF THE AREA..WITH SFC WINDS DECOUPLING NICELY BY LATE AFTERNOON/EVENING SUNDAY. WITH DEEP FRESH SNOW COVER IN PLACE...HAVE CONTINUED THE TREND OF UNDERCUTTING GUIDANCE BY A FEW DEGREES. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY ACTIVE PATTERN LOOKS LIKE IT WILL CONTINUE INTO THE EXTENDED PERIOD WITH MODELS SHOWING A COUPLE MORE STORM SYSTEMS MOVING ACROSS THE NORTHERN PLAINS. FIRST ONE SHOWS UP MONDAY NIGHT AND COULD REMAIN IN THE AREA THROUGH TUESDAY NIGHT. MODELS IN GOOD AGREEMENT WITH SFC PRESSURE PATTERN DURING THIS EVENT BUT DISAGREE A BIT ON PLACEMENT OF QPF. LOOKS LIKE ANOTHER INVERTED TROUGH AXIS SLIDES EASTWARD ACROSS THE NORTHERN PLAINS MONDAY NIGHT THROUGH TUESDAY AS FAIRLY POTENT 500 MB WAVE MOVES THROUGH. MOST MODELS SHOWING QPF ALL ACROSS THE NORTHERN CWA BUT STILL SOME DISAGREEMENT ON HOW FAR SOUTH TO PUT QPF...TAPERING OFF SOMEWHERE NEAR I-90. HAVE THEREFORE INCREASED POPS TO JUST UNDER LIKELY BUT TAPERED OFF ACROSS THE SOUTHWESTERN CWA. POCKET OF COLD 850 MB AIR IN THE TEENS BELOW ZERO TO AROUND -20 C MOVES IN BEHIND THIS SYSTEM. SO AGAIN...LOOKING AT LOWS BELOW ZERO WITH HIGHS PROBABLY ONLY IN THE SINGLE DIGITS ON WEDNESDAY AFTER THE STORM HAS PASSED. LOOKING TO THURSDAY...LEFT SLIGHT CHANCE POPS IN ACROSS THE FAR NORTHERN CWA. GFS STILL SHOWING WEAK WAVE OVER THE AREA BUT EC AND CANADIAN HAVE NOTHING AT ALL. IF GFS BEGINS TO BACK OFF ON THIS WAVE MORE LIKE THE EC/CANADIAN THEN POPS MAY BE ABLE TO BE PULLED. LOOKING FARTHER AHEAD...EC/GFS SHOWING YET ANOTHER STORM SYSTEM MOVING ACROSS THE AREA FOR NEXT FRIDAY. TEMPERATURES WERE CHANGED LITTLE THROUGHOUT THE PERIOD AND WILL CONTINUE TO BE BELOW NORMAL AS COLD PATTERN CONTINUES. && .AVIATION... SNOW IS ENDING FROM WEST TO EAST IN THIS AREA. LATEST SATELLITE LOOP OF VISIBLE PICTURES SUGGEST AN EDGE OF THE CLOUDS APPROACHING THE INTERSTATE 29 CORRIDOR. WSR-88D LOOP SHOWS THE BACK EDGE OF THE SNOW SLIGHTLY FARTHER EAST. TAF LOCATIONS IN THE EAST ARE STILL MARGINAL VFR OR IFR IN BLOWING SNOW. IN THE NORTH CENTRAL MOBRIDGE IS REPORTING GOOD VFR WITH WIND GUST AROUND 25-30 KTS. IN THE SOUTH CENTRAL PART OF THE STATE PIERRE CONTINUES TO REPORT IFR CONDITIONS IN BLOWING SNOW. EXPECT SLANT RANGE VISIBILITY IS HIGHER BUT AIRCRAFT OPERATIONS ON THE GROUND WOULD STILL BE IFR. THROUGH TODAY CONDITIONS WILL IMPROVE AS FRONTAL BOUNDARY MOVES EAST. VISIBILITY WILL IMPROVE TO VFR LATER THIS AFTERNOON AS NEW SNOW SETTLES. TONIGHT EXPECT ABOUT THE SAME IN WATERTOWN WITH SLOW IMPROVEMENT AS SNOW SETTLES. ALL LOCATIONS WILL SEE STRONG NORTHWEST WIND THROUGH TOMORROW. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WIND CHILL WARNING UNTIL 12 PM CST /11 AM MST/ SUNDAY FOR BROWN- BUFFALO-CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES- HYDE-JONES-LYMAN-MCPHERSON-POTTER-SPINK-STANLEY-SULLY- WALWORTH. WIND CHILL WARNING FROM 6 AM TO 12 PM CST SUNDAY FOR CLARK- CODINGTON-DAY-DEUEL-GRANT-HAMLIN-MARSHALL-ROBERTS. BLIZZARD WARNING UNTIL 6 AM CST SUNDAY FOR CLARK-CODINGTON-DAY- DEUEL-GRANT-HAMLIN-MARSHALL-ROBERTS. MN...WIND CHILL WARNING FROM 6 AM TO 12 PM CST SUNDAY FOR BIG STONE- TRAVERSE. BLIZZARD WARNING UNTIL 6 AM CST SUNDAY FOR BIG STONE-TRAVERSE. && $$ UPDATE...DORN SHORT TERM...HINTZ LONG TERM...TMT AVIATION...KEEFE WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 1107 AM CST SAT DEC 20 2008 .UPDATE... A COUPLE OF UPDATES FORTHCOMING THIS MORNING. THIS FIRST UPDATE IS JUST TO CLEAN UP THE FIRST PERIOD GRIDDED FORECAST. SNOW HAS NEARLY ENDED NOW ACROSS THE EASTERN FORECAST AREA. IN THE MEANTIME...THE STRONG NORTHWEST WINDS DID ACTUALLY CATCH UP TO THE FALLING SNOW THIS MORNING ACROSS THE JAMES RIVER VALLEY AND POINTS EAST. BLIZZARD CONDITIONS HAVE BEEN ONGOING ACROSS FAR NORTHEAST SOUTH DAKOTA AND WEST CENTRAL MINNESOTA THIS MORNING IN FALLING/BLOWING SNOW AND STRENGTHENING NORTHWEST WINDS. MUCH OF CENTRAL AND NORTH CENTRAL SOUTH DAKOTA PICKED UP AN INCH OR TWO OF SNOW LAST NIGHT...WHILE THE JAMES RIVER VALLEY AND POINTS EAST PICKED UP ANYWHERE FROM 2 TO 7 INCHES OF SNOWFALL AND SOME AREAS ARE STILL SNOWING. THE PLAN IS TO REARRANGE SOME OF THE HEADLINES WITHIN THE NEXT HOUR OR SO TO CHANGE WINTER WEATHER ADVISORY AREAS TO A WIND CHILL HEADLINE AND TO DROP BROWN AND SPINK COUNTIES FROM A BLIZZARD WARNING TO SOME FORM OF WIND CHILL HEADLINE. FROM MARSHALL...DAY AND CLARK COUNTIES EAST...WILL CONTINUE WITH A BLIZZARD WARNING THROUGH AT LEAST THE REST OF TODAY. WHENEVER THE FALLING SNOW ENDS...VISBIES START TO IMPROVE...DESPITE THE STRONG WINDS AND BLOWING SNOW. FOR NOW THOUGH...GIVEN THE EXTENT OF SNOWFALL OUT EAST AND THE CONTINUED FALLING SNOW AT THE MOMENT...WILL ALLOW THAT BLIZZARD WARNING OUT EAST...INCLUDING THE I-29 CORRIDOR...TO CONTINUE. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH MONDAY. MAIN FCST CHALLENGE FACING THE NEAR TERM DEALS WITH ONGOING PCPN AND BLIZZARD POTENTIAL...AND TEMPS FOR THE REST OF THE WEEKEND. LATEST MSAS ANLYS SHOWS INVERTED SFC TROF NOW JUST EAST OF THE JAMES RIVER VALLEY...WITH SFC WINDS NW BEHIND THIS FEATURE. WINDS ARE BEGINNING TO INCREASE OUT BY THE MO RIVER...WITH KMBG GUSTING TO 30MPH AND KPIR HAVING A PEAK WIND TO 36 MPH. NAM/GFS AGREE THAT MAIN AREA OF FORCING WILL SLIP THROUGH THE ERN PART OF THE CWA BY 12Z...AND MOVE INTO MN BY 15Z. THIS COINCIDES NICELY WITH MAIN AREA OF 7H THETA-E FORCING ALSO SLIDING EAST OF THE CWA BY 15Z...WITH DOWNGLIDE THEN MOVING IN THEREAFTER. WITH BUFKIT SHOWING DECENT OMEGA LIFTING THROUGH SNOWGROWTH AREA...SHOULD BE ABLE TO SQUEEZE OUT 2-3 INCHES OF LIGHT FLUFFY SNOW PRIOR TO WINDS SHOWING UP. WHICH...IF IT WEREN`T FOR THE WIND POTENTIAL...BLIZZARD WARNING COULD MOST LIKELY BE LOWERED TO A SNOW/BS ADVRY. HOWEVER...LATEST RUC IS SHOWING 925MB GEOSTROPHIC WINDS ON THE ORDER OF 30 TO 40 KTS...AND GIVEN CURRENT GUSTS SETTING UP ACROSS THE MO RIVER AREA...THINK THAT VSBYS WILL BEGIN TO DIMINISH RAPIDLY AS THE WINDS HIT THE POWDER ACROSS THE BLIZZARD WARNING AREA. HAVE INCLUDED SPINK COUNTY IN THE BLIZZARD WARNING AS CALL PLACED TO LAW ENFORCEMENT CONFIRMS 1.5" OF NEW SNOW WITH VSBYS LOWERING ACROSS THE WESTERN SECTIONS OF THE COUNTY DUE TO BLSN. FURTHER WEST...SNOW AMOUNTS SHOULD BE DRAMATICALLY LESS...SO WILL LET THE WINTER WEATHER ADVRY RIDE FOR SNOW/BLSN. TIMING THE END OF THE HEADLINE WILL BE AN ISSUE. DEFINITE BACK EDGE OF SNOW CAN BE SEEN ON KABR 88D...BUT PERSISTANT STRONG WINDS WILL DETERIME LENGTH OF HEADLINE. FOR NOW...HAVE OPTED TO KEEP HEADLINE EXPIRATION TIME AS INHERITED JUST TO KEEP THINGS SIMPLE AND CONSISTENT...ALTHOUGH FEEL IT MAY BE A BIT LONG WHEN LOOKING AT SNOW PRODUCTION TIMING. AS DOWNGLIDE SWEEPS EAST ACROSS THE CWA...EXPECT THE SNOW TO END RATHER RAPIDLY DURING THE DAY...WITH BLSN BEING THE MAIN WEATHER FACTOR. HAVE DECREASED POPS QUICKER THAN INHERITED...BUT KEPT MENTION OF BLSN GOING. WITH STRONG CAA SWEEPING IN...HAVE ALSO CONTINUED TREND OF FALLING TEMPS THROUGH THE DAY. 7H CLOSED LOW SWEEPS SOUTH AND EAST OF THE AREA THROUGH 12Z SUNDAY...WITH BACKDOOR 7H TROF DROPPING THROUGH THE EAST. MAY PROVIDE JUST ENOUGH FOCUS FOR LIGHT SNOW/FLURRIES TO REDEVELOP DURING THE LATE MORNING THROUGH THE AFTERNOON ON SUNDAY...BUT LITTLE IF ANY ADDITIONAL ACCUMULATIONS EXPECTED. THEN COMES THE COLD. NAM CONTS TO SHOW 1035MB ARCTIC HIGH DROPPING INTO THE MIDWEST AND SETTING UP SHOP. COND PRESSURE DEFICITS SHOW THAT CLOUDS SHOULD ERODE/MOVE OUT OF THE AREA..WITH SFC WINDS DECOUPLING NICELY BY LATE AFTERNOON/EVENING SUNDAY. WITH DEEP FRESH SNOW COVER IN PLACE...HAVE CONTINUED THE TREND OF UNDERCUTTING GUIDANCE BY A FEW DEGREES. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY ACTIVE PATTERN LOOKS LIKE IT WILL CONTINUE INTO THE EXTENDED PERIOD WITH MODELS SHOWING A COUPLE MORE STORM SYSTEMS MOVING ACROSS THE NORTHERN PLAINS. FIRST ONE SHOWS UP MONDAY NIGHT AND COULD REMAIN IN THE AREA THROUGH TUESDAY NIGHT. MODELS IN GOOD AGREEMENT WITH SFC PRESSURE PATTERN DURING THIS EVENT BUT DISAGREE A BIT ON PLACEMENT OF QPF. LOOKS LIKE ANOTHER INVERTED TROUGH AXIS SLIDES EASTWARD ACROSS THE NORTHERN PLAINS MONDAY NIGHT THROUGH TUESDAY AS FAIRLY POTENT 500 MB WAVE MOVES THROUGH. MOST MODELS SHOWING QPF ALL ACROSS THE NORTHERN CWA BUT STILL SOME DISAGREEMENT ON HOW FAR SOUTH TO PUT QPF...TAPERING OFF SOMEWHERE NEAR I-90. HAVE THEREFORE INCREASED POPS TO JUST UNDER LIKELY BUT TAPERED OFF ACROSS THE SOUTHWESTERN CWA. POCKET OF COLD 850 MB AIR IN THE TEENS BELOW ZERO TO AROUND -20 C MOVES IN BEHIND THIS SYSTEM. SO AGAIN...LOOKING AT LOWS BELOW ZERO WITH HIGHS PROBABLY ONLY IN THE SINGLE DIGITS ON WEDNESDAY AFTER THE STORM HAS PASSED. LOOKING TO THURSDAY...LEFT SLIGHT CHANCE POPS IN ACROSS THE FAR NORTHERN CWA. GFS STILL SHOWING WEAK WAVE OVER THE AREA BUT EC AND CANADIAN HAVE NOTHING AT ALL. IF GFS BEGINS TO BACK OFF ON THIS WAVE MORE LIKE THE EC/CANADIAN THEN POPS MAY BE ABLE TO BE PULLED. LOOKING FARTHER AHEAD...EC/GFS SHOWING YET ANOTHER STORM SYSTEM MOVING ACROSS THE AREA FOR NEXT FRIDAY. TEMPERATURES WERE CHANGED LITTLE THROUGHOUT THE PERIOD AND WILL CONTINUE TO BE BELOW NORMAL AS COLD PATTERN CONTINUES. && .AVIATION... MVFR/IFR CIGS/VSBYS WILL CONTINUE AT ALL TAF SITES THROUGH THE EARLY MORNING HOURS IN -SN/SN/+SN AND AREAS OF BLSN. AS NORTHWEST WINDS INCREASE ACROSS THE AREA THIS MORNING...LIFR/VLIFR VSBYS CAN BE EXPECTED. THESE CONDITIONS WILL BE MOST PREVALENT AT KABR/KATY THROUGHOUT THE MORNING AND INTO THE AFTERNOON. CONDITIONS WILL BEGIN TO IMPROVE SLOWLY ACROSS KMBG/KPIR THROUGHOUT THE MORNING HOURS. THE SNOW WILL TAPER OFF LATER THIS MORNING ACROSS KMBG/KPIR BUT WILL NOT END ACROSS KABR/KATY UNTIL THE AFTERNOON. AREAS OF BLSN WILL REMAIN ACROSS THE AREA THROUGHOUT THE DAY WITH LOWER VSBYS ACROSS KABR/KATY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 6 AM CST /5 AM MST/ SUNDAY FOR BUFFALO-CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES- HYDE-JONES-LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH. BLIZZARD WARNING UNTIL 6 AM CST SUNDAY FOR BROWN-CLARK-CODINGTON- DAY-DEUEL-GRANT-HAMLIN-MARSHALL-ROBERTS-SPINK. MN...BLIZZARD WARNING UNTIL 6 AM CST SUNDAY FOR BIG STONE-TRAVERSE. && $$ UPDATE...DORN SHORT TERM...HINTZ LONG TERM...TMT AVIATION...TMT WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 401 AM CST SAT DEC 20 2008 .SHORT TERM...TODAY THROUGH MONDAY. MAIN FCST CHALLENGE FACING THE NEAR TERM DEALS WITH ONGOING PCPN AND BLIZZARD POTENTIAL...AND TEMPS FOR THE REST OF THE WEEKEND. LATEST MSAS ANLYS SHOWS INVERTED SFC TROF NOW JUST EAST OF THE JAMES RIVER VALLEY...WITH SFC WINDS NW BEHIND THIS FEATURE. WINDS ARE BEGINNING TO INCREASE OUT BY THE MO RIVER...WITH KMBG GUSTING TO 30MPH AND KPIR HAVING A PEAK WIND TO 36 MPH. NAM/GFS AGREE THAT MAIN AREA OF FORCING WILL SLIP THROUGH THE ERN PART OF THE CWA BY 12Z...AND MOVE INTO MN BY 15Z. THIS COINCIDES NICELY WITH MAIN AREA OF 7H THETA-E FORCING ALSO SLIDING EAST OF THE CWA BY 15Z...WITH DOWNGLIDE THEN MOVING IN THEREAFTER. WITH BUFKIT SHOWING DECENT OMEGA LIFTING THROUGH SNOWGROWTH AREA...SHOULD BE ABLE TO SQUEEZE OUT 2-3 INCHES OF LIGHT FLUFFY SNOW PRIOR TO WINDS SHOWING UP. WHICH...IF IT WEREN`T FOR THE WIND POTENTIAL...BLIZZARD WARNING COULD MOST LIKELY BE LOWERED TO A SNOW/BS ADVRY. HOWEVER...LATEST RUC IS SHOWING 925MB GEOSTROPHIC WINDS ON THE ORDER OF 30 TO 40 KTS...AND GIVEN CURRENT GUSTS SETTING UP ACROSS THE MO RIVER AREA...THINK THAT VSBYS WILL BEGIN TO DIMINISH RAPIDLY AS THE WINDS HIT THE POWDER ACROSS THE BLIZZARD WARNING AREA. HAVE INCLUDED SPINK COUNTY IN THE BLIZZARD WARNING AS CALL PLACED TO LAW ENFORCEMENT CONFIRMS 1.5" OF NEW SNOW WITH VSBYS LOWERING ACROSS THE WESTERN SECTIONS OF THE COUNTY DUE TO BLSN. FURTHER WEST...SNOW AMOUNTS SHOULD BE DRAMATICALLY LESS...SO WILL LET THE WINTER WEATHER ADVRY RIDE FOR SNOW/BLSN. TIMING THE END OF THE HEADLINE WILL BE AN ISSUE. DEFINITE BACK EDGE OF SNOW CAN BE SEEN ON KABR 88D...BUT PERSISTANT STRONG WINDS WILL DETERIME LENGTH OF HEADLINE. FOR NOW...HAVE OPTED TO KEEP HEADLINE EXPIRATION TIME AS INHERITED JUST TO KEEP THINGS SIMPLE AND CONSISTENT...ALTHOUGH FEEL IT MAY BE A BIT LONG WHEN LOOKING AT SNOW PRODUCTION TIMING. AS DOWNGLIDE SWEEPS EAST ACROSS THE CWA...EXPECT THE SNOW TO END RATHER RAPIDLY DURING THE DAY...WITH BLSN BEING THE MAIN WEATHER FACTOR. HAVE DECREASED POPS QUICKER THAN INHERITED...BUT KEPT MENTION OF BLSN GOING. WITH STRONG CAA SWEEPING IN...HAVE ALSO CONTINUED TREND OF FALLING TEMPS THROUGH THE DAY. 7H CLOSED LOW SWEEPS SOUTH AND EAST OF THE AREA THROUGH 12Z SUNDAY...WITH BACKDOOR 7H TROF DROPPING THROUGH THE EAST. MAY PROVIDE JUST ENOUGH FOCUS FOR LIGHT SNOW/FLURRIES TO REDEVELOP DURING THE LATE MORNING THROUGH THE AFTERNOON ON SUNDAY...BUT LITTLE IF ANY ADDITIONAL ACCUMULATIONS EXPECTED. THEN COMES THE COLD. NAM CONTS TO SHOW 1035MB ARCTIC HIGH DROPPING INTO THE MIDWEST AND SETTING UP SHOP. COND PRESSURE DEFICITS SHOW THAT CLOUDS SHOULD ERODE/MOVE OUT OF THE AREA..WITH SFC WINDS DECOUPLING NICELY BY LATE AFTERNOON/EVENING SUNDAY. WITH DEEP FRESH SNOW COVER IN PLACE...HAVE CONTINUED THE TREND OF UNDERCUTTING GUIDANCE BY A FEW DEGREES. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY ACTIVE PATTERN LOOKS LIKE IT WILL CONTINUE INTO THE EXTENDED PERIOD WITH MODELS SHOWING A COUPLE MORE STORM SYSTEMS MOVING ACROSS THE NORTHERN PLAINS. FIRST ONE SHOWS UP MONDAY NIGHT AND COULD REMAIN IN THE AREA THROUGH TUESDAY NIGHT. MODELS IN GOOD AGREEMENT WITH SFC PRESSURE PATTERN DURING THIS EVENT BUT DISAGREE A BIT ON PLACEMENT OF QPF. LOOKS LIKE ANOTHER INVERTED TROUGH AXIS SLIDES EASTWARD ACROSS THE NORTHERN PLAINS MONDAY NIGHT THROUGH TUESDAY AS FAIRLY POTENT 500 MB WAVE MOVES THROUGH. MOST MODELS SHOWING QPF ALL ACROSS THE NORTHERN CWA BUT STILL SOME DISAGREEMENT ON HOW FAR SOUTH TO PUT QPF...TAPERING OFF SOMEWHERE NEAR I-90. HAVE THEREFORE INCREASED POPS TO JUST UNDER LIKELY BUT TAPERED OFF ACROSS THE SOUTHWESTERN CWA. POCKET OF COLD 850 MB AIR IN THE TEENS BELOW ZERO TO AROUND -20 C MOVES IN BEHIND THIS SYSTEM. SO AGAIN...LOOKING AT LOWS BELOW ZERO WITH HIGHS PROBABLY ONLY IN THE SINGLE DIGITS ON WEDNESDAY AFTER THE STORM HAS PASSED. LOOKING TO THURSDAY...LEFT SLIGHT CHANCE POPS IN ACROSS THE FAR NORTHERN CWA. GFS STILL SHOWING WEAK WAVE OVER THE AREA BUT EC AND CANADIAN HAVE NOTHING AT ALL. IF GFS BEGINS TO BACK OFF ON THIS WAVE MORE LIKE THE EC/CANADIAN THEN POPS MAY BE ABLE TO BE PULLED. LOOKING FARTHER AHEAD...EC/GFS SHOWING YET ANOTHER STORM SYSTEM MOVING ACROSS THE AREA FOR NEXT FRIDAY. TEMPERATURES WERE CHANGED LITTLE THROUGHOUT THE PERIOD AND WILL CONTINUE TO BE BELOW NORMAL AS COLD PATTERN CONTINUES. && .AVIATION... MVFR/IFR CIGS/VSBYS WILL CONTINUE AT ALL TAF SITES THROUGH THE EARLY MORNING HOURS IN -SN/SN/+SN AND AREAS OF BLSN. AS NORTHWEST WINDS INCREASE ACROSS THE AREA THIS MORNING...LIFR/VLIFR VSBYS CAN BE EXPECTED. THESE CONDITIONS WILL BE MOST PREVALENT AT KABR/KATY THROUGHOUT THE MORNING AND INTO THE AFTERNOON. CONDITIONS WILL BEGIN TO IMPROVE SLOWLY ACROSS KMBG/KPIR THROUGHOUT THE MORNING HOURS. THE SNOW WILL TAPER OFF LATER THIS MORNING ACROSS KMBG/KPIR BUT WILL NOT END ACROSS KABR/KATY UNTIL THE AFTERNOON. AREAS OF BLSN WILL REMAIN ACROSS THE AREA THROUGHOUT THE DAY WITH LOWER VSBYS ACROSS KABR/KATY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 6 AM CST /5 AM MST/ SUNDAY FOR BUFFALO-CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES- HYDE-JONES-LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH. BLIZZARD WARNING UNTIL 6 AM CST SUNDAY FOR BROWN-CLARK-CODINGTON- DAY-DEUEL-GRANT-HAMLIN-MARSHALL-ROBERTS-SPINK. MN...BLIZZARD WARNING UNTIL 6 AM CST SUNDAY FOR BIG STONE-TRAVERSE. && $$ SHORT TERM...HINTZ LONG TERM...TMT AVIATION...TMT WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 1101 AM CST SAT DEC 20 2008 .UPDATE... CURRENT RADAR-SATELLITE TRENDS INDICATE BEST RAIN SHOWER COVERAGE SHOULD FAVOR THE SOUTHERN HALF OF MIDDLE TENNESSEE TODAY...THEN SHIFT A LITTLE NORTHWARD THIS EVENING AS A LOW PRESSURE AREA NEAR THE AR-MO BORDER TRACKS EASTWARD. HAVE LOWERED TEMPS SLIGHTY BASED ON AREA SURFACE OBSERVATIONS...WITH HIGHS ABOUT 5 DEGREES COOLER THAN PREVIOUS FORECAST. WARMER TEMPS SHOULD FAVOR THE SOUTH HALF AS WELL...THOUGH ITS DOUBTFUL THE INSTABILITY NEEDED FOR THUNDERSTORMS WILL DEVELOP AND HAVE REMOVED THAT FROM THE FORECAST AS WELL. LOW-MID LEVEL LAPSE RATES BARELY PEAK ABOVE 5C/KM PER RUC ANALYSIS AND CURRENT LIGHTNING DETECTION SHOWS NO STRIKES IN THE AREA. && PREV DISCUSSION... /ISSUED 358 AM CST SAT DEC 20 2008/ SHORT TERM (SAT-MON)... SFC LOW PRES DEVELOPMENT IN MID TN TODAY AS BOUNDARY MOVES BACK NORTH AS A WARM FRONT. PRES GRAD LIGHT WITH LESS WIND SPEED THAN FRI...WITH AN AFTERNOON SHIFT TO THE SOUTH. TEMPS LOOK TO GET INTO THE 60S SOUTH. ISO THUNDER WITH GFS/NAM DESTAB TO ZERO IN THE SHOWALTER. COLD FRONT SHOULD MOVE THROUGH MID-STATE AFTER MIDNIGHT TONIGHT. MAJOR PUSH OF COLD AIR SUN. H8 TEMPS FALL TO 14-18 BELOW ZERO SUN WHICH WL TRANSLATE INTO TEMPS STRUGGLING TO HIT THE FREEZING MARK. THERE WL BE SOME SUN SUNDAY...BUT ALSO SCT FLURRIES. DRY WITH VERY COLD ARCTIC AIR SUN NIGHT...WITH DANGEROUS SUBZERO WIND CHILLS. WIND CHILL OUTLOOK ACR MID TN SUN NIGHT IN HAZARDOUS WEATHER OUTLOOK PRODUCT AND GRAPHICS. CONTINUED DRY AND COLD MON. LONG TERM (TUE-FRI)... ARCTIC AIR CLINGS TO THE SFC TUE AS 850-MB LVL UP MOISTENS INTO PRECIPITATION. MODELS MAY BE TOO QUICK WITH PCPN TUE BUT WL CONTINUE WITH A CHANCE OF WINTER WEATHER. ASSOCIATED COLD FRONT MOVES THROUGH CHRISTMAS EVE...WITH DRY CONDITIONS EXPECTED ON CHRISTMAS. NOT A MAJOR COOLDOWN IN THE FAR EXTENDED...WITH TEMPS AOA NORMAL ADVERTISED. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ LAROSA tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPOKANE WA 1108 AM PST FRI DEC 19 2008 .SYNOPSIS... AN ARCTIC AIR MASS WILL INVADE THE REGION AS THE RECORD SNOWFALL PRODUCING WINTER STORM DEPARTS TODAY. BITTER COLD WEATHER WILL CONTINUE THROUGH THE WEEKEND...WITH ANOTHER STRONG SNOW STORM EXPECTED SUNDAY AND MONDAY. THE COLD AND UNSETTLED WEATHER PATTERN WILL LAST THROUGH CHRISTMAS. && .DISCUSSION... SATELLITE IMAGERY AT 18Z SHOWS CLOUDS DECREASING OVER NORTH CENTRAL WASHINGTON THROUGH THE COLUMBIA BASIN. THE HIGH TEMPERATURES FOR MUCH OF THE REGION HAVE BEEN ADJUSTED UPWARD GIVEN THE LATEST SATELLITE TRENDS. DESPITE THE CLEARING OVER PORTIONS OF CENTRAL AND EASTERN WASHINGTON...DEEP LAYER INSTABILITY CONTINUES TO PRODUCE LIGHT SNOW SHOWERS AROUND SPOKANE...PULLMAN...AND THE CENTRAL PANHANDLE. THE 12Z SOUNDING FROM SPOKANE SHOWS VERY STEEP LAPSE RATES FROM 750-500MB. EVEN THE SMALLEST DISTURBANCES ROTATING AROUND THE CENTER OF THE UPPER LOW IN SOUTHERN ALBERTA...WILL PRODUCE SNOW SHOWERS THROUGH THE AFTERNOON. ACCORDING TO THE RUC AND 12Z NAM...THERE IS A MINOR 500MB TROUGH THAT WILL MOVE FROM SOUTH CENTRAL WASHINGTON INTO THE SOUTHERN PANHANDLE BY 21Z. BEHIND THIS SUBTLE 500MB TROUGH... SURFACE HIGH PRESSURE WILL DESCEND OUT OF BRITISH COLUMBIA. LOCALLY GUSTY WINDS HAVE ALREADY DEVELOPED IN THE OKANOGAN VALLEY AND PORTIONS OF THE WATERVILLE PLATEAU. GUSTS BETWEEN 25 AND 30 MPH THROUGH THE OKANOGAN VALLEY ARE EXPECTED THIS AFTERNOON AND THIS EVENING CONTRIBUTING TO AREAS OF BLOWING SNOW. ELSEWHERE...WITHOUT THE EFFECTS OF TERRAIN CHANNELING WINDS SHOULD BE 10 MPH OR LESS...AND THE THREAT FOR BLOWING SNOW WILL BE SOMEWHAT LESS. /GKOCH && .AVIATION... SCATTERED SNOW SHOWERS WILL AFFECT THE SPOKANE...PULLMAN...COEUR D`ALENE...AND LEWISTON AIRPORTS THROUGH 20-22Z. VISIBILITIES MAY BE AS LOW AS 2SM IN SOME OF THESE SNOW SHOWERS. THE LIGHT WINDS AND ABUNDANCE OF SNOW WILL BRING THE POTENTIAL FOR FOG AND STRATUS OVERNIGHT...BUT THE CONFIDENCE THAT IT WILL DEVELOP IS NOT HIGH. DRIER ARCTIC AIR WILL DESCEND FROM CANADA OVERNIGHT...BUT MAY NOT BE A STRONG ENOUGH PUSH OF DRY AIR TO PRECLUDE THE DEVELOPMENT OF FOG OR STRATUS. /GKOCH && .PRELIMINARY POINT TEMPS/POPS... SPOKANE 15 -2 5 -3 19 13 / 20 10 0 40 80 70 COEUR D`ALENE 16 0 4 -2 21 16 / 30 10 0 20 90 80 PULLMAN 19 5 11 7 27 20 / 30 10 0 40 90 80 LEWISTON 21 7 15 10 30 22 / 40 10 0 20 90 80 COLVILLE 16 -6 4 -4 18 12 / 10 10 0 30 70 50 SANDPOINT 17 -3 3 -7 16 14 / 30 10 0 10 70 70 KELLOGG 17 2 3 -6 20 17 / 50 20 10 20 90 90 MOSES LAKE 17 0 10 8 20 11 / 0 10 10 80 100 40 WENATCHEE 11 3 7 6 16 13 / 0 0 10 90 100 40 OMAK 12 -4 7 0 17 10 / 0 0 0 60 80 30 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...NONE. WA...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY EVENING FOR WATERVILLE PLATEAU...WENATCHEE AREA. WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY EVENING FOR EAST SLOPES NORTHERN CASCADES. WINTER STORM WATCH FROM SATURDAY EVENING THROUGH LATE SUNDAY NIGHT FOR MOSES LAKE AREA...UPPER COLUMBIA BASIN. && $$ wa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 316 PM CST SAT DEC 20 2008 .SHORT TERM...LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW AN UPPER LOW SPINNING ACROSS THE NORTHERN PLAINS...WITH AN INVERTED SURFACE TROUGH EXTENDING FROM NORTHERN MN TO EASTERN IA. RELATIVELY STRONGER SHORTWAVE ROTATING AROUND THIS UPPER LOW IS HELPING TO GENERATE WIDESPREAD LIGHT TO MODERATE SNOW THAT HAS BEEN SPREADING ACROSS MUCH OF THE STATE THIS AFTERNOON. UPSTREAM REPORTS SHOW GENERALLY 2-4 INCHES ACROSS MINNESOTA WITH ISOLATED 5-6 INCH AMOUNTS. SE FLOW LIGHT LAKE EFFECT HASNT BEEN THAT RESPONSIVE TO INCREASING MID-LEVEL MOISTURE...BUT HAVE TO THINK THAT WILL QUICKLY CHANGE AS LIGHT SNOW MOVES IN. AS FORCING FROM THE APPROACHING SHORTWAVE AND TROUGH INCREASES...SNOW ACCUMS AND HEADLINES ARE THE OBVIOUS FORECAST CONCERNS THROUGH TOMORROW. TONIGHT...STRONG SHORTWAVE ROTATING AROUND THE UPPER LOW OVER THE NORTHERN PLAINS WILL HEAD TOWARDS SOUTHERN LAKE MICHIGAN...WHILE PUSHING AN INVERTED SURFACE TROUGH OUR DIRECTION. STRONG POCKET OF -DIVQ ALONG WITH SOME MID-LEVEL FGEN WILL CONTINUE TO ADVANCE THE LIGHT TO MODERATE SNOW OVER THE WESTERN AND CENTRAL PART OF THE STATE NORTHEAST THROUGH THE LATE AFTERNOON HOURS. THIS FORCING WILL SLOW ITS FORWARD PROGRESS TONIGHT...AND GIVE NORTH-CENTRAL AND NE WISCONSIN A PROLONGED PERIOD OF SNOW. LOOKING AT MODEL CROSS-SECTIONS...MUCH OF THIS FORCING IS ABOVE THE DENDRITIC GROWTH ZONE...SUGGESTING HIGHER END SNOW-LIQUID RATIOS BETWEEN 15-25:1 IS THE WAY TO GO. OTHER TECHNIQUES LIKE THE ROEBBER/COBB ALSO SAY THAT 15-20:1 RATIOS ARE MORE LIKELY. MODEL QPFS SUGGEST ANYWHERE BETWEEN 0.25 TO 0.35 IN LIQUID WILL FALL LATE THIS AFTERNOON THROUGH TONIGHT...WHICH WOULD EQUATE TO ABOUT 4 TO 6 INCHES OVER AN 12-18 HOUR PERIOD ACROSS THE FORECAST AREA. HIGHEST AMOUNTS WILL RESIDE OVER AREAS ADJACENT TO LAKE MICHIGAN DUE TO 6-9 HOURS OF SE FLOW LAKE ENHANCEMENT. HAVE TOSSED AROUND THE IDEA OF UPGRADING TO WARNINGS DUE TO THIS ENHANCEMENT...ESPECIALLY HEADING NORTH OVER KEWAUNEE/DOOR/MARINETTE WHERE ENHANCEMENT WILL OCCUR THE LONGEST. GIVEN UNCERTAINTIES WITH CURRENT STRUGGLING LAKE EFFECT...AND IN COLLABORATION WITH MQT...FEEL ITS BEST TO STAY THE COURSE AND LET THE EVENING CREW SEE HOW THIS ENHANCEMENT EVOLVES BEFORE OPENING ANOTHER CAN OF WORMS. LASTLY...AS THE COLD FRONT GRINDS TO A HALT ACROSS THE AREA OVERNIGHT...SNOW WILL COME TO AN END FIRST ACROSS CENTRAL WISCONSIN...WITH GUSTY NW WINDS CREATING BLOWING AND DRIFTING SNOW. TOMORROW...WITH THE UPPER LOW DIRECTLY OVERHEAD...THE INVERTED TROUGH HANGS UP ACROSS THE U.P./WI BORDER FOR MUCH OF THE MORNING BEFORE SHIFTING SOUTH WHILE WASHING OUT DURING THE AFTERNOON. NORTH TO NW WINDS BETWEEN 30-40 KNOTS AT 850MB WILL INCREASE THROUGH THE DAY AS IT BRINGS DOWN COLDER AIR IN THE NEG UPPER TEENS. THIS WILL EVENTUALLY CRANK UP SOME LAKE ENHANCEMENT OFF LAKE SUPERIOR TOWARDS VILAS AND ONEIDA COUNTIES THAT WILL ADD ON SEVERAL MORE INCHES THROUGH THE AFTERNOON. AS A RESULT...ALL LOCATIONS WILL SEE OCCASIONAL LIGHT SNOW OR SNOW SHOWERS THROUGH THE DAY...BUT THE HIGHEST ACCUMULATIONS WILL RESIDE ACROSS THE NORTHERN FORECAST AREA...AND SPECIFICALLY INTO VILAS COUNTY WHERE 2-4 ADDITIONAL INCHES WILL FALL. OTHERWISE...A GENERAL HALF INCH SOUTH TO 3 NORTH LOOKS GOOD. WITH THE INVADING ARCTIC AIR AND GUSTY NW WIND...TEMPS WILL RANGE FROM THE MIDDLE SINGLE DIGITS OVER CENTRAL WI TO THE LOWER 20S OVER THE DOOR PENINSULA. WIND CHILLS WILL APPROACH -20F OVER CENTRAL WI. .LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY...ACTIVE PATTERN CONTINUES...WITH LINGERING LES...BLOWING SNOW AND WIND CHILL CONCERNS SUN NGT INTO MONDAY...THE POTENTIAL FOR MORE SNOW TUES INTO WEDS... AND PERHAPS ANOTHER STG SYSTEM WITH MIXED PCPN AT THE END OF THE WORK WEEK. WINTER WX ADVISORIES WILL CONTINUE INTO SUNDAY EVG ACROSS VILAS/ONEIDA COUNTIES...WHERE RESIDUAL LK-EFFECT SNOW SHOWERS WILL BRING AN ADDL 1-3 INCHES OF SNOW. THE SNOW WILL TAPER OFF OVERNIGHT AS WINDS BACK AND DRIER AIR ADVECTS ACROSS WSTRN LK SUP. A TIGHTENING PRESSURE GRADIENT...CAA...AND AN INCREASING ISALLOBARIC GRADIENT WILL KEEP BLUSTERY/WINDY CONDITIONS IN THE FCST FOR AT LEAST THE EVG HOURS... WITH A GRADUAL DECREASE DURING THE OVERNIGHT HOURS. HAVE KEPT AREAS OF BLOWING SNOW IN THE FCST...BUT BUMPED UP TO DEFINITE BLOWING SNOW ALONG THE LKSHR...WHERE FREQUENT GUSTS TO 35 TO 40 MPH ARE LIKELY. WOULD NOT BE SURPRISED IF WE NEED TO ISSUE A BLOWING SNOW ADVISORY OR PERHAPS EVEN A BRIEF BLIZZARD WARNING FOR THE LKSHR COUNTIES ON SUNDAY NIGHT. WILL ALSO EVENTUALLY NEED WIND CHILL ADVISORY HEADLINES...AS WIND CHILLS PLUMMET TO -20 TO -30 OVER ALL BUT FAR NE WI SUNDAY NIGHT...AND REMAIN BLO CRITERIA INTO MONDAY MORNING. AFTER A BRIEF DRY PERIOD BENEATH A TRANSITORY HIGH PRESSURE SYSTEM ON MONDAY AND EARLY MONDAY NIGHT...STG ISENT LIFT WILL BRING SNOW BACK TO THE FORECAST AREA LATE MONDAY NIGHT INTO TUESDAY. WITH STG DYNAMICS ASSOC WITH AN UPPER LEVEL JET AND A 40+ KT LLJ...AND MIXING RATIOS INCREASING TO 2.5-3.0 G/KG...THIS SYSTEM LOOKS LIKE IT HAS THE POTENTIAL TO BE AN ADVISORY EVENT. WHAT IS PERHAPS EVEN MORE INTERESTING IS THE STG SFC WAVE THAT THE ECMWF DEEPENS ALONG THE FRONTAL BOUNDARY...AND MOVES THROUGH THE WSTRN GREAT LKS ON WEDNESDAY. THE GFS WAS SHOWING SOMETHING SIMILAR ABOUT 3 MODEL RUNS AGO...LENDING A LITTLE MORE CREDENCE TO THIS SOLN. MADE SOME LAST MINUTE ADJUSTMENTS TO THE WEDS FCST...AND INCREASED POPS TO LIKELY OVER OUR EASTERN COUNTIES. IF THE ECMWF VERIFIES...THIS COULD BE THE SECOND PUNCH OF A DECENT SNOW STORM. A SIMILAR SETUP OCCURS DURING THE THURSDAY NIGHT THROUGH FRIDAY NIGHT PERIOD...WITH PCPN DEVELOPING DUE TO INCREASING ISENT LIFT THURSDAY NIGHT...FOLLOWED BY A STG LOW PRESSURE SYSTEM MOVG THROUGH THE RGN FRIDAY INTO FRIDAY NIGHT. THE MAIN DIFFERENCE IS THE TRACK...WHICH IS MUCH FARTHER TO THE WEST...RESULTING IN THE WARM SECTOR LIFTING THROUGH MUCH OF WI...AND ASSOC PCPN TYPE ISSUES. HAVE INCREASED POPS DURING THIS PERIOD...RAISED TEMPS... AND MENTIONED A MIX OF RAIN/SNOW IN THE FRIDAY FCST FOR NOW. && .AVIATION...SNOW WILL CONTINUE TO SPREAD ACROSS THE TAF SITES LATE THIS AFTERNOON AND THROUGH MUCH OF THE OVERNIGHT HOURS...BEFORE DIMINISHING FIRST AT AUW/CWA LATE. CONDITIONS IN THE SNOW WILL GENERALLY RANGE FROM LIFR TO IFR. OCCASIONAL SNOW WILL CONTINUE FOR MUCH OF THE DAY TOMORROW...WITH THE HIGHEST ACCUMS NEAR RHI WHERE A LOW LEVEL TROUGH IN COMBINATION WITH LAKE ENHANCEMENT WILL BOOST SNOWFALL RATES. NORTHWEST WINDS WILL ALSO BECOME GUSTY LATE TONIGHT FOR CWA/AUW AND TOMORROW MORNING FOR RHI/GRB WHICH WILL CAUSE BLOWING AND DRIFTING SNOW. A GRADUAL IMPROVEMENT TREND IN THE CIGS/VSBYS SHOULD OCCUR LATE IN THE DAY TOMORROW. && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 6 PM CST SUNDAY FOR WIZ011>013- 018>022-030-031-035>040-045-048>050-073-074. WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST SUNDAY NIGHT FOR WIZ005-010. && $$ MPC/KIECKBUSCH wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 300 PM CST SAT DEC 20 2008 .SHORT TERM...THROUGH TUESDAY NIGHT PRIMARY FORECAST CONCERNS ASSOCIATED WITH DANGEROUS MULTI-THREAT WINTER STORM IMPACTING THE AREA THROUGH SUNDAY. IN FACT...WE STRONGLY ENCOURAGE THE BROADCAST MEDIA TO EMPHASIZE TO THE PUBLIC THAT THIS STORM SHOULD NOT BE TAKEN LIGHTLY. AFTERNOON SURFACE ANALYSIS HAD DISTINCT ARCTIC FRONT ENTERING SOUTHEAST MN AND NORTHEAST IOWA AS OF 21Z...WITH TROWAL EXTENDING FROM MISSISSIPPI RIVER NORTHWARD TOWARD LAKE WINNIPEG. SIGNIFICANT DROP IN VISIBILITY TO LESS THAN A MILE NOTED IMMEDIATELY BEHIND THE SURFACE FRONT DUE TO STRONG NORTHWEST WIND GUSTS OF 30 TO 35KTS PRODUCING CONSIDERABLE BLOWING SNOW. WATER VAPOR IMAGERY INDICATED PRIMARY MID LEVEL CIRCULATION LOCATED NEAR NORTH DAKOTA CANADIAN BORDER...WHILE SHORT WAVE TRACKING INTO SOUTHWEST MN. SNOWFALL WAS OCCURRING OVER MUCH OF THE FORECAST AREA IN RESPONSE TO UPPER LEVEL DIVERGENCE AND STRONG ISENTROPIC LIFT IN THE 270K-280K LAYER. CONFIDENCE WAS HIGH IN OVERALL DETAILS OF THE FORECAST...ESPECIALLY FOR THIS WEEKEND. THIS WAS BASED ON EXCELLENT CLUSTERING OF UPPER LEVEL AND SURFACE FEATURES IN THE 20.12Z DATA SUITE OF NCEP AND EUROPEAN MODELS. IN ADDITION...20.12Z ARX HIGH RESOLUTION MODELS CORROBORATED THIS DATA...AS DID 20.15Z SREF PROBABILISTIC DATA. LOOKING AHEAD...THERE WERE TIMING DIFFERENCES ON NEXT SYSTEM TO AFFECT THE AREA EARLY NEXT WEEK. GFS AND EUROPEAN MODEL SUITE SUGGESTED A FASTER PROGRESSION THAN NAM/WRF...AS DID 15.12Z SREF. TONIGHT...MID LEVEL CIRCULATION EXPECTED TO DEEPEN AS IT SHIFTS SOUTHEASTWARD INTO THE UPPER MISSISSIPPI VALLEY. AT SAME TIME...ARCTIC FRONT PUSHES EASTWARD ACROSS THE FORECAST AREA. HEAVIEST SNOWFALL ANTICIPATED TO PUSH EAST OF THE FORECAST AREA... AS FORCING ASSOCIATED WITH TROWAL ROTATES TOWARD GREAT LAKES. MAIN THREATS THEN WILL BE STRONG NORTHWEST WINDS...ALONG WITH ATTENDANT BLOWING SNOW AND BITTERLY COLD WIND CHILLS. 20.12Z ARXMESOWRF AND ARXRUCWRF INDICATED CORE OF 850MB WINDS OF 45-50KTS SHOULD FOCUS ACROSS IOWA TONIGHT. EVEN SO...BUFKIT FORECAST SOUNDINGS SUPPORTED 850MB MOMENTUM TRANSFER AROUND 40KTS TO BRUSH SOUTHWEST PERIPHERY OF OUR FORECAST AREA. AS A RESULT...HIGHEST POTENTIAL FOR SUSTAINED AND WIDESPREAD BLIZZARD CONDITIONS RESIDES A BIT FURTHER SOUTH OF OUR FORECAST AREA. THEREFORE...AFTER COORDINATION WITH SURROUNDING NWS SITES...OPTED TO MAINTAIN WINTER STORM WARNING AREAWIDE THROUGH SUNDAY TO BEST ADDRESS MULTI-THREATS. EVEN SO...LOW DENSITY SNOW SHOULD BLOW CONSIDERABLY TONIGHT... ESPECIALLY IN THE WIND PRONE AREAS OF SOUTHEAST MN...NORTHEAST IOWA AND RIDGETOPS OF SOUTHWEST WI. NEAR BLIZZARD AND NEAR WHITEOUT CONDITIONS WILL BE A FACTOR IN THE AFOREMENTIONED AREAS. THIS SHOULD BE ESPECIALLY TRUE DURING INITIAL 2-6 HOURS FROM ONSET OF WINDS...UNTIL SNOW COMPACTS AND THUS VISIBILITY IMPROVES. THIS BASED ON WORK DONE BY JUNGBLUTH IN 1998...AS WELL OTHER WORK DONE ON BLOWING SNOW FORECASTING BY KAPELA...LEFTWICH AND VAN ESS IN 1995. NOT ONLY WILL BLOWING SNOW BE PROBLEMATIC...BUT COMBINE IN EFFECTS OF WIND CHILLS DROPPING TO 20 BELOW TO 35 BELOW DURING THE OVERNIGHT AND ONE CAN SEE WHY THIS STORM IS DANGEROUS. FOR FURTHER DETAILS CONCERNING HAZARDS ASSOCIATED WITH THIS STORM...PLEASE REFERENCE LATEST SHORT TERM FORECASTS...WINTER WEATHER STATEMENTS AND LOCAL HAZARDOUS WEATHER OUTLOOK. SUNDAY...TROWAL SIGNATURE PIVOTS SOUTHWARD ACROSS THE FORECAST AREA...BRINGING LIKELIHOOD OF LIGHT SNOW. HOWEVER...MAIN CONCERN CONTINUES TO BE WITH BITTER COLD WIND CHILLS AND BLOWING/DRIFTING SNOW. 1000-850 LAPSE RATES EXPECTED TO STEEPEN...WHICH SHOULD ONLY ENHANCE THE EFFECT OF TRANSFERRING MOMENTUM OF 40KTS TOWARD THE SURFACE...AS SUGGESTED BUFKIT FORECAST SOUNDINGS. EVEN THOUGH WINDS WILL BE STRONG...COMPACTED SNOW SHOULD EFFECTIVELY PREVENT TOO MUCH OF A SIGNIFICANT VISIBILITY RESTRICTION. SUNDAY NIGHT INTO MONDAY MORNING...WINDS EXPECTED TO DIMINISH AS UPPER LEVEL AND SURFACE SYSTEM MOVES FURTHER EASTWARD. EVEN SO...AMBIENT AIR TEMPERATURES SHOULD BE VERY COLD AND THUS WINDS SHOULD CONTINUE TO CREATE BITTERLY COLD WIND CHILLS. WE ANTICIPATE HEADLINES WILL SHIFT TO WIND CHILLS IN THIS TIME FRAME...WHICH SHOULD BE ADDRESSED ONCE WINTER STORM WARNING HEADLINES HAVE EXPIRED. MONDAY NIGHT INTO TUESDAY NIGHT...YET ANOTHER SURFACE AND UPPER LEVEL WAVE EXPECTED TO IMPACT THE AREA...AS ACTIVE STORM TRACK CONTINUES ACROSS NATIONS MIDSECTION. BASED ON GFS...EUROPEAN...AND SREF DATA SUITE...OPTED TO INCREASE AND/OR EXPAND SNOW PROBABILITIES MONDAY NIGHT INTO TUESDAY. THIS WAS BASED ON CONSISTENT SIGNAL OF DEEP LAYERED Q-G CONVERGENCE...AS WELL AS ISENTROPIC LIFT IN THE 275K-285K LAYER. .LONG TERM...WEDNESDAY THROUGH SATURDAY WITH ONGOING WINTER STORM...DID NOT SPEND TOO MUCH TIME WITH DETAILS IN THE EXTENDED OUTLOOK. HOWEVER...FOCUS IN THIS TIME FRAME CONTINUES TO BE ON PARADE OF WINTER WEATHER PRODUCING SYSTEMS EXPECTED TO IMPACT THE UPPER MISSISSIPPI VALLEY. DETERMINISTIC 20.12Z ECMWF AND GFS HAD THEIR DIFFERENCES WITH TIMING OF UPPER LEVEL AND SURFACE WAVES ACROSS THE MIDWEST. THEREFORE... FORECAST CONFIDENCE LOWERS WITH RESPECT TO OVERALL DETAILS. EVEN SO...WAVES EJECTING FROM SOUTHWEST U.S. ALONG BAROCLINIC ZONE APPEAR TO SUPPORT PERIODIC PRECIPITATION EVENTS ACROSS THE FORECAST AREA DURING THE LATTER HALF OF THE WEEK. THEREFORE...CONTINUED SNOW PROBABILITIES AS IN CURRENT DATA BASE...WITH NO CHANGES MADE TO THE EXTENDED OUTLOOK. OF NOTE...THERE HAS BEEN A SIGNAL OF A POTENTIAL PRECIPITATION TYPE ISSUE AT THE END OF THE WEEK. 20.12Z GFS AND ECMWF CONTINUED TO INDICATE DIFFERING LOW LEVEL THERMAL STRUCTURES...WHICH LENDS LOW CONFIDENCE AT THIS POINT TO IDENTIFY ANY DETAIL WITH REGARD TO PRECIPITATION TYPE. && .AVIATION... MAIN FORECAST CONCERN IS BLOWING SNOW THIS EVENING AND CONTINUING INTO TONIGHT. LATEST 17Z SURFACE ANALYSIS INDICATES SURFACE COLD FRONT EXTENDING FROM NEAR NORTH CENTRAL MINNESOTA INTO SOUTHERN IOWA. THE COLD FRONT WILL MOVE EAST OVER BOTH TAF SITES LATE THIS AFTERNOON AND INTO THE EARLY EVENING HOURS. LATEST 15Z RUC MODEL INDICATING STRONG ISENTROPIC LIFT AT 280K SURFACE OUT AHEAD OF SURFACE COLD FRONT. THIS IS PRODUCING MODERATE SNOW ACROSS MUCH OF SOUTHEAST MINNESOTA AND WESTERN WISCONSIN AT THIS TIME. BOTH TAF SITES ARE REPORTING VISIBILITIES OF A HALF MILE WITH RST CEILING LOWERING TO 100 FEET. LIFR AND VLIFR CONDITIONS WILL CONTINUE AT BOTH TAF SITES THROUGH THE AFTERNOON AND EVENING HOURS...AS COLD FRONT PUSHES EAST OF TAF SITES. BEHIND SURFACE COLD FRONT...TIGHT PRESSURE GRADIENT WILL ALLOW FOR AN INCREASE IN SUSTAINED WINDS OF 20 TO 25 KNOTS AND GUSTS UP TO 30 TO 35 KNOTS AT BOTH TAF SITES. COMBINED WITH NEW SNOWFALL AND STRONG WINDS...VISIBILITIES WILL BE REDUCED TO A QUARTER OF A MILE AT RST TAF SITE BETWEEN 21Z-00Z...DUE TO THE BLOWING SNOW. AN UPPER LEVEL SHORTWAVE TROUGH OVER SOUTHERN CANADA IS EXPECTED TO MOVE SOUTH OVER THE TAF SITES AFTER 15Z SUNDAY. THIS WILL ALLOW PRESSURE GRADIENT TO REMAIN TIGHT ACROSS SOUTHEAST MINNESOTA AND WESTERN WISCONSIN SUNDAY. ALONG WITH STRONG WINDS...LIGHT SNOW WILL ACCOMPANY THE SHORTWAVE TROUGH AND CONTINUE THE POTENTIAL FOR REDUCE VISIBILITIES AT BOTH TAF SITES AFTER 18Z SUNDAY. LATER TAF ISSUANCES WILL DIAGNOSE THE IMPACT THE WINDS AND VISIBILITIES WILL HAVE AT BOTH RST AND LSE SITES AFTER 18Z. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR WIZ017-WIZ029- WIZ032-WIZ033-WIZ034-WIZ041-WIZ042-WIZ043-WIZ044-WIZ053- WIZ054-WIZ055-WIZ061. MN...WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR MNZ079-MNZ086- MNZ087-MNZ088-MNZ094-MNZ095-MNZ096. IA...WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR IAZ008-IAZ009- IAZ010-IAZ011-IAZ018-IAZ019-IAZ029-IAZ030. && $$ SHORT/LONG TERM...THOMPSON AVIATION..........DAS/DTJ wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 1032 AM CST SAT DEC 20 2008 .UPDATE...12Z SURFACE/RUC ANALYSIS AND IR/WV/RADAR IMAGERY SHOW AN AREA OF LOW PRESSURE TRAVERSING ACROSS MINNESOTA AND IOWA WITH A SWATH OF SNOW AHEAD OF IT ALREADY SPREADING INTO WESTERN WISCONSIN. TIMING TOOL AND 09Z SREF SUGGEST THIS SNOW WILL REACH THE FAR WESTERN FORECAST AREA BY MIDDAY...WHICH IS A BIT QUICKER THAN PREVIOUSLY FORECASTED. ALSO...LIGHT LAKE EFFECT SNOW OFF LAKE MICHIGAN CONTINUES BUT HAS BEEN BREAKING UP THROUGH THE MORNING AS A RESULT OF A LIGHTENING WIND FIELD. THESE WINDS ARE PROJECTED TO PICK UP AGAIN DURING THE AFTERNOON AND WITH THE APPROACH OF SYNOPTIC MOISTURE...BELIEVE SNOW WILL INCREASE AND EXPAND THROUGH THE AFTERNOON. WITH THESE ITEMS IN MIND...WILL MOVE UP THE START OF THE CURRENT ADVISORIES BY THREE HOURS. ACCUMULATIONS STILL LOOK TO BE THE HIGHEST ACROSS THE WEST...POSSIBLY REACHING TWO INCHES BY THE START OF THE EVENING. UNTIL THE SYNOPTIC SNOWS ARRIVE...LAKE EFFECT SNOW SHOWERS SHOULD RESULT IN LESS THAN AN INCH. UPDATED WSW AND ZONES ALREADY OUT. MPC && .PREV DISCUSSION...ISSUED AT 505 AM CST SAT DEC 20 2008... SHORT TERM...LATEST RUC ANALYSIS AND SAT IMAGERY SHOWING UPPER LOW JUST NORTH OF THE MT BORDER. SIG VORT MAX SOUTH OF LOW OVER WESTERN SD. AT THE SURFACE...HIGH PRESSURE SLIPPING EAST THROUGH ONTARIO...WITH INVERTED TROF OVER WESTERN MN. LOCALLY...EAST FLOW OFF LAKE HAS LED LES SHOWERS...MOVING INLAND TO GRB. STRONGEST BANDS OVERNIGHT HAVE BEEN IN KEWAUNEE AND SOUTHERN DOOR. SIG TEMPERATURE SPREAD OVER THE AREA WITH LAND O LAKES AT -17 AND LAKESHORE AREAS NEAR +20. COOLER INLAND TEMPERATURES LEADING TO COASTAL SURFACE WINDS TURNING OFFSHORE PAST HOUR OR SO WEAKENING LES. THOUGH WITH DAYBREAK AND CONTINUED ONSHORE SYNOPTIC FLOW...BELIEVE BANDS WILL PUSH BACK ONSHORE...THOUGH WEAKER WITH LIMITED FETCH AS WINDS A BIT MORE EASTERLY. WILL MENTION SCATTERED WORDING. ELSEWHERE INCREASING CLOUDS AND FEW FLURRIES SEEN IN WEAK WAA AHEAD OF SURFACE TROF. MODELS ALL CONSISTENT IN SHOWING BEST DYNAMICS LATE THIS AFTERNOON AND TONIGHT AS VORT SWINGS THROUGH SOUTHERN WI/NORTHERN IL. CYCLOGENISIS EXPECTED TONIGHT ALONG BAROCLINIC ZONE TO THE SOUTH WITH MODEL SOUNDINGS SHOWING BEST LIFT AROUND OR AFTER 00Z. HAVE PUSHED BACK START OF WSW SLIGHTLY. MODELS PRETTY CONSISTENT ON QPF...THOUGH LEANED TOWARDS GFS WITH BETTER CAPTURE OF ONGOING LES. COBB METHOD SUGGESTS SNOW RATIONS BETWEEN 14 AND 18 TO 1. DEEPENING SURFACE LOW TO LEAD TO STRENGTHENING WINDS SUNDAY. WILL BE CONSERVATIVE ON WIND SPEEDS...ESPECIALLY EAST GIVEN TROF LINGERING BACK OVER NORTHEAST WI. WINDS BECOME FAVORABLE FOR LES OVER VILAS LATER IN THE AFTERNOON. DID NOT MAKE ANY CHANGES TO AMOUNTS...THOUGH HAVE CONCERNS ON SNOW SHOWERS STAYING TOGETHER WITH STRENGTH OF FLOW. LONG TERM...SUNDAY NIGHT THROUGH FRIDAY INVERTED TROUGH MOVING AWAY AND A DEEPENING LOW PRESSURE SYSTEM EAST OF WISCONSIN WILL PRODUCE BLUSTERY TO WINDY CONDITIONS EARLY SUNDAY NIGHT OVER MUCH OF THE AREA. PER COORDINATION WITH THE SHORT TERM FORECASTER...DECIDED TO HOLD OFF ON EXTENDING THE ADVISORY OVER NORTHEAST WISCONSIN SINCE IT IS ALREADY A LONG DURATION EVENT. BASED ON THE POWDERY NATURE OF THE SNOW...SHOULD BE A FAIR AMOUNT OF BLOWING AND DRIFTING OF THE SNOW SUNDAY EVENING. ALSO CONCERNED ABOUT THE DOOR PENINSULA WHERE SOME OF THE BAY HAS FROZEN OVER ALREADY. WHERE THE BAY HAS ICED OVER...THE GUSTY WINDS AND FRESH SNOW COULD PRODUCE SOME NASTY CONDITIONS OVER DOOR COUNTY WITH LOW VISIBILITIES. LATER SHIFTS WILL NEED TO MONITOR THIS SITUATION AND MAKE THE APPROPRIATE ADJUSTMENTS TO THE ADVISORIES IF NEEDED. OTHERWISE...LAKE EFFECT SNOW SHOWERS WILL CONTINUE ACROSS VILAS COUNTY THROUGH MUCH OF THE NIGHT. AFTER SUCH A COLD AFTERNOON ON MONDAY...IT APPEARS LOWS MONDAY NIGHT WILL OCCUR DURING THE EVENING AND THEN RISE OVERNIGHT AS SOUTHERLY WINDS RETURN TO THE AREA AND CLOUDS WILL BE ON THE INCREASE. IF THE HIGH IS ABOUT 6 HOURS SLOWER WITH THE INCOMING SYSTEM...TEMPERATURES COULD REALLY TANK UNDER THE HIGH PRESSURE SYSTEM. ATTENTION TURNS TO THE NEXT WINTER STORM THAT WILL AFFECT THE AREA TUESDAY INTO WEDNESDAY. AT LEAST SEVERAL INCHES OF SNOW ARE EXPECTED WITH THIS SYSTEM ACROSS MUCH OF THE AREA. HAVE RAISED SNOW CHANCES FOR LATE MONDAY NIGHT OVER THE FAR WEST... AND RAISED CHANCES FOR SNOW INTO THE LIKELY CATEGORY TUESDAY AND HIGH CHANCE CATEGORY TUESDAY NIGHT. ANY SNOW SHOULD TAPER OFF WEDNESDAY MORNING. HIGH PRESSURE WILL SLIDE ACROSS THE AREA ON CHRISTMAS MORNING. TEMPERATURES ON THIS MORNING COULD REALLY TANK AS WELL. THE ONLY PROBLEM IS THE GFS DEPICTS WEAK WARM ADVECTION AND PRECIPITATION BREAKING OUT ON THE BACK SIDE OF THE RIDGE FOR CHRISTMAS DAY. HAVE DECIDED NOT ADD ANY MENTION OF SNOW FOR CHRISTMAS DAY AS THE ECMWF DID NOT DEPICT THIS FEATURE. THE NEXT SIGNIFICANT WINTER STORM WILL AFFECT THE AREA...POSSIBLY BEGINNING AS EARLY AS THE DAY AFTER CHRISTMAS (FRIDAY) OR THAT WEEKEND. ECMWF IS QUICKER THAN THE GFS AND FOLLOWED BASED ON PATTERN OVER THE LAST FEW WEEKS WITH SYSTEMS PASSING THROUGH THE REGION EVERY FEW DAYS. DESPITE THE DIFFERENCES BETWEEN THE GFS AND ECMWF...PRECIPITATION WILL MORE THAN LIKELY BE AN ISSUE AS BOTH MODELS BRING TEMPERATURES AT OR ABOVE 0 C AT 850MB AT SOME POINT DURING THE STORM. THE MODELS DIVERGE ON THE STRENGTH AND HOW FAR NORTH THE VERY WARM AIR GETS. FOR SIMPLICITY SAKE...WILL CONTINUE WITH SNOW IN THE FORECAST. LATER SHIFTS WILL MORE THAN LIKELY WILL NEED TO ADJUST PRECIPITATION TYPE TO INCLUDE RAIN...DD FREEZING RAIN...OR SLEET AND MAY NEED TO REMOVE THE SNOW IN SOME AREAS. JUST TOO EARLY TO DETERMINE PRECIPITATION TYPE. SINCE IT WILL BE THE WEEKEND AFTER CHRISTMAS AND THERE WILL BE MANY PEOPLE TRAVELING...WILL HIGHLIGHT IN THE HAZARDOUS WEATHER OUTLOOK. AVIATION...WIDESPREAD MVFR CIGS AND FLURRIES OR LIGHT SNOW SHOWERS THIS MORNING...WITH DETERIORATING CONDITIONS THIS AFTERNOON ACROSS ALL AREAS AS NEXT WINTER STORM SYSTEM APPROACHES. && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 6 PM CST SUNDAY FOR WIZ011>013-020>022-038>040-048>050-073-074. WINTER WEATHER ADVISORY UNTIL 6 PM CST SUNDAY FOR WIZ018-019-030- 031-035>037-045. WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO MIDNIGHT CST SUNDAY NIGHT FOR WIZ005-010. && $$ wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 505 AM CST SAT DEC 20 2008 .SHORT TERM...LATEST RUC ANALYSIS AND SAT IMAGERY SHOWING UPPER LOW JUST NORTH OF THE MT BORDER. SIG VORT MAX SOUTH OF LOW OVER WESTERN SD. AT THE SURFACE...HIGH PRESSURE SLIPPING EAST THROUGH ONTARIO...WITH INVERTED TROF OVER WESTERN MN. LOCALLY...EAST FLOW OFF LAKE HAS LED LES SHOWERS...MOVING INLAND TO GRB. STRONGEST BANDS OVERNIGHT HAVE BEEN IN KEWAUNEE AND SOUTHERN DOOR. SIG TEMPERATURE SPREAD OVER THE AREA WITH LAND O LAKES AT -17 AND LAKESHORE AREAS NEAR +20. COOLER INLAND TEMPERATURES LEADING TO COASTAL SURFACE WINDS TURNING OFFSHORE PAST HOUR OR SO WEAKENING LES. THOUGH WITH DAYBREAK AND CONTINUED ONSHORE SYNOPTIC FLOW...BELIEVE BANDS WILL PUSH BACK ONSHORE...THOUGH WEAKER WITH LIMITED FETCH AS WINDS A BIT MORE EASTERLY. WILL MENTION SCATTERED WORDING. ELSEWHERE INCREASING CLOUDS AND FEW FLURRIES SEEN IN WEAK WAA AHEAD OF SURFACE TROF. MODELS ALL CONSISTENT IN SHOWING BEST DYNAMICS LATE THIS AFTERNOON AND TONIGHT AS VORT SWINGS THROUGH SOUTHERN WI/NORTHERN IL. CYCLOGENISIS EXPECTED TONIGHT ALONG BAROCLINIC ZONE TO THE SOUTH WITH MODEL SOUNDINGS SHOWING BEST LIFT AROUND OR AFTER 00Z. HAVE PUSHED BACK START OF WSW SLIGHTLY. MODELS PRETTY CONSISTENT ON QPF...THOUGH LEANED TOWARDS GFS WITH BETTER CAPTURE OF ONGOING LES. COBB METHOD SUGGESTS SNOW RATIONS BETWEEN 14 AND 18 TO 1. DEEPENING SURFACE LOW TO LEAD TO STRENGTHENING WINDS SUNDAY. WILL BE CONSERVATIVE ON WIND SPEEDS...ESPECIALLY EAST GIVEN TROF LINGERING BACK OVER NORTHEAST WI. WINDS BECOME FAVORABLE FOR LES OVER VILAS LATER IN THE AFTERNOON. DID NOT MAKE ANY CHANGES TO AMOUNTS...THOUGH HAVE CONCERNS ON SNOW SHOWERS STAYING TOGETHER WITH STRENGTH OF FLOW. .LONG TERM...SUNDAY NIGHT THROUGH FRIDAY INVERTED TROUGH MOVING AWAY AND A DEEPENING LOW PRESSURE SYSTEM EAST OF WISCONSIN WILL PRODUCE BLUSTERY TO WINDY CONDITIONS EARLY SUNDAY NIGHT OVER MUCH OF THE AREA. PER COORDINATION WITH THE SHORT TERM FORECASTER...DECIDED TO HOLD OFF ON EXTENDING THE ADVISORY OVER NORTHEAST WISCONSIN SINCE IT IS ALREADY A LONG DURATION EVENT. BASED ON THE POWDERY NATURE OF THE SNOW...SHOULD BE A FAIR AMOUNT OF BLOWING AND DRIFTING OF THE SNOW SUNDAY EVENING. ALSO CONCERNED ABOUT THE DOOR PENINSULA WHERE SOME OF THE BAY HAS FROZEN OVER ALREADY. WHERE THE BAY HAS ICED OVER...THE GUSTY WINDS AND FRESH SNOW COULD PRODUCE SOME NASTY CONDITIONS OVER DOOR COUNTY WITH LOW VISIBILITIES. LATER SHIFTS WILL NEED TO MONITOR THIS SITUATION AND MAKE THE APPROPRIATE ADJUSTMENTS TO THE ADVISORIES IF NEEDED. OTHERWISE...LAKE EFFECT SNOW SHOWERS WILL CONTINUE ACROSS VILAS COUNTY THROUGH MUCH OF THE NIGHT. AFTER SUCH A COLD AFTERNOON ON MONDAY...IT APPEARS LOWS MONDAY NIGHT WILL OCCUR DURING THE EVENING AND THEN RISE OVERNIGHT AS SOUTHERLY WINDS RETURN TO THE AREA AND CLOUDS WILL BE ON THE INCREASE. IF THE HIGH IS ABOUT 6 HOURS SLOWER WITH THE INCOMING SYSTEM...TEMPERATURES COULD REALLY TANK UNDER THE HIGH PRESSURE SYSTEM. ATTENTION TURNS TO THE NEXT WINTER STORM THAT WILL AFFECT THE AREA TUESDAY INTO WEDNESDAY. AT LEAST SEVERAL INCHES OF SNOW ARE EXPECTED WITH THIS SYSTEM ACROSS MUCH OF THE AREA. HAVE RAISED SNOW CHANCES FOR LATE MONDAY NIGHT OVER THE FAR WEST... AND RAISED CHANCES FOR SNOW INTO THE LIKELY CATEGORY TUESDAY AND HIGH CHANCE CATEGORY TUESDAY NIGHT. ANY SNOW SHOULD TAPER OFF WEDNESDAY MORNING. HIGH PRESSURE WILL SLIDE ACROSS THE AREA ON CHRISTMAS MORNING. TEMPERATURES ON THIS MORNING COULD REALLY TANK AS WELL. THE ONLY PROBLEM IS THE GFS DEPICTS WEAK WARM ADVECTION AND PRECIPITATION BREAKING OUT ON THE BACK SIDE OF THE RIDGE FOR CHRISTMAS DAY. HAVE DECIDED NOT ADD ANY MENTION OF SNOW FOR CHRISTMAS DAY AS THE ECMWF DID NOT DEPICT THIS FEATURE. THE NEXT SIGNIFICANT WINTER STORM WILL AFFECT THE AREA...POSSIBLY BEGINNING AS EARLY AS THE DAY AFTER CHRISTMAS (FRIDAY) OR THAT WEEKEND. ECMWF IS QUICKER THAN THE GFS AND FOLLOWED BASED ON PATTERN OVER THE LAST FEW WEEKS WITH SYSTEMS PASSING THROUGH THE REGION EVERY FEW DAYS. DESPITE THE DIFFERENCES BETWEEN THE GFS AND ECMWF...PRECIPITATION WILL MORE THAN LIKELY BE AN ISSUE AS BOTH MODELS BRING TEMPERATURES AT OR ABOVE 0 C AT 850MB AT SOME POINT DURING THE STORM. THE MODELS DIVERGE ON THE STRENGTH AND HOW FAR NORTH THE VERY WARM AIR GETS. FOR SIMPLICITY SAKE...WILL CONTINUE WITH SNOW IN THE FORECAST. LATER SHIFTS WILL MORE THAN LIKELY WILL NEED TO ADJUST PRECIPITATION TYPE TO INCLUDE RAIN...DD FREEZING RAIN...OR SLEET AND MAY NEED TO REMOVE THE SNOW IN SOME AREAS. JUST TOO EARLY TO DETERMINE PRECIPITATION TYPE. SINCE IT WILL BE THE WEEKEND AFTER CHRISTMAS AND THERE WILL BE MANY PEOPLE TRAVELING...WILL HIGHLIGHT IN THE HAZARDOUS WEATHER OUTLOOK. && .AVIATION...WIDESPREAD MVFR CIGS AND FLURRIES THIS MORNING...WITH DETERIORATING CONDITIONS THIS AFTERNOON ALL AREAS AS NEXT WINTER STORM SYSTEM APPROACHES. && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR WIZ011>013-020>022-038>040-048>050-073-074. WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 6 PM CST SUNDAY FOR WIZ018-019-030-031-035>037-045. WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO MIDNIGHT CST SUNDAY NIGHT FOR WIZ005-010. && $$ TE/ECKBERG wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 346 PM CST FRI DEC 19 2008 .SHORT TERM...TONIGHT AND TOMORROW...LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW THE VIGOROUS SHORTWAVE AND ASSOCIATED SURFACE LOW RACING TO THE EAST OVER THE EASTERN GREAT LAKES. WIDESPREAD SNOW ENDED EARLY IN THE AFTERNOON...BUT NORTHEAST WINDS BETWEEN THIS SURFACE LOW AND HIGH PRESSURE OVER THE CENTRAL PLAINS HAS GENERATED LIGHT LAKE EFFECT SNOW SHOWERS FOR AREAS ADJACENT TO GREEN BAY AND LAKE MICHIGAN. ADDITIONALLY...FUNNELING OF THESE WINDS ACROSS GREEN BAY AND THE FOX VALLEY HAS LED TO BEEFIER GUSTS THAN THE SURROUNDING AREAS (GUSTS TO 30 MPH) THIS AFTERNOON AND BLOWING AND DRIFTING SNOW. MEANWHILE...NEXT SYSTEM OVER THE PAC NW HAS ITS AIM ON THE WESTERN GREAT LAKES FOR TOMORROW. SO...CONCERNS FOR THE SHORT TERM INCLUDE LAKE EFFECT ACCUMS AND TEMPS TONIGHT...AND SNOW TIMING/ACCUMS/HEADLINES FOR THE WEEKEND SYSTEM. TONIGHT...SHORTWAVE RIDGING WILL WORK ACROSS THE AREA WHILE SURFACE HIGH PRESSURE WILL CONTINUE TO BE PRESENT ACROSS CENTRAL ONTARIO. LOW LEVEL WINDS EMANATING FROM THIS SURFACE HIGH WILL START OUT FROM THE NORTHEAST AND GRADUALLY VEER AROUND TO THE EAST OVERNIGHT WHILE DIMINISHING TO LESS THAN 10 KTS. INSTABILITY OVER LAKE MICHIGAN WILL REMAIN IN THE MID TEENS...MORE THAN SUFFICIENT FOR LAKE EFFECT POSSIBILITIES. 850-700MB MOISTURE WILL THIN OUT SOMEWHAT AS DRIER AIR ROTATES IN FROM THE NORTH OVERNIGHT. BUT THROUGH THE EVENING...CANNOT REALLY FIND A REASON WHY ONGOING LIGHT NE LAKE EFFECT WILL NOT CONTINUE WHILE THE FETCH ORIGINATES OVER FAR NORTHERN LAKE MICHIGAN. LACK OF INSTABILITY AND MID-LEVEL MOISTURE WILL LIMIT ACCUMS...BUT CAN SEE AROUND AN INCH OF ADDITIONAL ACCUMS NEAR LAKE MICHIGAN. LOW TEMPERATURES ARE TOUGH...DEPENDING ON HOW MUCH CLEARING OCCURS. BELIEVE A LIGHTENING WIND FLOW WILL HELP DECREASE CLOUD COVER SOMEWHAT ACROSS FAR NORTHERN WISCONSIN...REMOVED FROM THE MOISTURE FLUXES OFF LAKE MICHIGAN. IF SUFFICIENT CLEARING DOES OCCUR...TEMPERATURES WILL BE SEVERAL DEGREES COOLER THAN CURRENTLY FORECASTED. TOMORROW...UPPER LOW OVER THE PAC NW WILL DEEPEN OVER THE NORTHERN PLAINS AS IT ENCOUNTERS STRONG JET ENERGY. INVERTED SURFACE TROUGH WITH A WEAK EMBEDDED SURFACE LOW WILL EDGE TOWARDS THE WESTERN GREAT LAKES BY AFTERNOON WITH INCREASING ASCENT VIA 700-500MB -DIVQ AND ISENTROPIC ASCENT. MODELS STILL DIFFER ON ARRIVAL TIMING OF THE PRECIP WITH THE NAM ON THE SLOWER SIDE...AND GFS/SREF ON THE FASTER SIDE...BRINGING HIGH POPS BETWEEN 15 AND 18Z TOMORROW MORNING. AT THIS POINT...PREFER THE FASTER TIMING AND WILL BRING IN HIGHER POPS FOR THE MORNING...BUT TRY TO SHOW MORE OF GRADIENT. SNOW WILL THEN SPREAD ACROSS MUCH OF THE FORECAST AREA FOR THE AFTERNOON. TAKING A LOOK AT A GFS CROSS-SECTION...MOST OF THE LIFT WILL OCCUR ABOVE THE DENDRITIC GROWTH ZONE AND INSTABILITY ISNT ALL THAT IMPRESSIVE. SO THINK SNOW WILL BE ON THE LIGHTER SIDE AND MAY REACH UP TO A COUPLE INCHES ACROSS THE WESTERN CWA BY THE END OF THE AFTERNOON. SNOW WILL CONTINUE INTO SATURDAY NIGHT (MORE BELOW)...BUT WILL START WEATHER ADVISORY HEADLINES DURING THE AFTERNOON. .LONG TERM...SATURDAY NIGHT THROUGH NEXT FRIDAY...MAIN FCST CONCERNS INCLUDE HEADLINES FOR THIS WEEKEND`S EVENT...AND PCPN TRENDS WITH OTHER POTENTIALLY SIGNIFICANT EVENTS ON TUES/TUES NGT AND THU-FRI. MAIN FOCUS IS ON THIS WEEKEND`S SYSTEM...AND ASSOCIATED WINTER WX HEADLINES. SNOW ASSOC WITH ISENT LIFT/WAA SHOULD BE ONGOING ACROSS MOST OF THE FA BY 00Z/SUN...AND WILL LIKELY BE ENHANCED BY FRONTOGENETIC FORCING ALONG THE ADVANCING ARCTIC FRONT SATURDAY EVG. CYCLOGENESIS IS EXPECTED TO OCCUR JUST TO OUR EAST ALONG THE ARCTIC BOUNDARY AS A DEEPENING UPPER LOW APPROACHES LATE SAT NGT. THIS WILL CAUSE THE FRONT TO BECOME NEARLY STATIONARY OVER N WI...THEN GRADUALLY SAG SOUTH ON SUNDAY. THE MOST SIGNIFICANT SNOWFALL ACCUMS SHOULD OCCUR LATE SATURDAY INTO SAT NGT... FOLLOWED BY LIGHTER ACCUMS ON SUNDAY. ACCUMS SHOULD TAPER OFF BY SUNDAY AFTERNOON ACROSS MOST OF THE FA...WITH THE EXCEPTION OF FAR NC WI...WHERE LES IS EXPECTED TO DEVELOP AS COLD NNW WINDS CROSS WSTRN LK SUP. LES SHOULD CONTINUE INTO SUNDAY EVG...THEN DIMINISH OVERNIGHT AS DRIER AIR ARRIVES AND WINDS BACK TO A WNW DIRECTION. EXPECT TOTAL ACCUMS TO RANGE FROM 4 TO 6 INCHES IN C/EC WI...TO 6 TO 8 INCHES NORTH WITH PSBL 10 INCH AMOUNTS IN WSTRN VILAS/NW ONEIDA COUNTIES. THESE ACCUMULATIONS WILL OCCUR OVER A LONG PERIOD...ROUGHLY 24 TO 30 HOURS (30-36 HOURS IN NC WI)...SO GENERALLY FALL BLO WARNING CRITERIA. HAVE TO FACTOR IN WINDS WITH THIS EVENT TOO...ALTHOUGH EFFECTS HERE WILL BE MINOR COMPARED TO OFFICES TO OUR WEST ADN SOUTH. WINDS WILL INITIALLY BE LIGHT ACROSS THE FA ON SATURDAY NIGHT DUE TO BAGGY CYCLONIC FLOW NEAR THE LINGERING FRONT. HOWEVER...WINDS ARE EXPECTED TO PICK UP ACROSS C/EC WI SUNDAY MORNING...AND ACROSS THE REST OF THE FA SUNDAY AFTERNOON. THIS SHD RESULT IN CONSIDERABLE DRIFTING SNOW AND PATCHY BLOWING SNOW. HAD THREE VIABLE OPTIONS FOR HEADLINES...ISSUE NOTHING RIGHT NOW... ISSUE WHAT APPEARS TO BE A BORDERLINE WATCH...OR GO WITH A HIGH CONFIDENCE WINTER WEATHER ADVISORY. OPTED TO GO WITH THE ADVISORY ATTM...MAINLY DUE TO EXPECTED MARGINAL SNOWFALL TOTALS OVER A LONG PERIOD...AND MARGINAL BLOWING SNOW POTENTIAL LATE IN THE EVENT. SUBSEQUENT SHIFTS CAN EASILY UPGRADE A PORTION OF THE ADVISORY TO A WARNING...IF NEEDED. THE MOST LIKELY SITUATIONS FOR AN UPGRADE WOULD BE THE DEVELOPMENT OF A NARROW BAND OF HEAVIER SNOW JUST NORTH OF THE DEEPENING H7/H5 LOWS AS THEY CROSS THE FA LATE SATURDAY NIGHT/EARLY SUNDAY...OR HEAVIER SNOWFALL ACCUMS IN NC WI DUE TO GREATER THAN EXPECTED LES SUNDAY AFT/EVG. MORE SNOW IS EXPECTED TUESDAY INTO TUESDAY NIGHT AS A 40-50 KT LLJ TAKES AIM ON WI. HAVE INCREASED POPS TO HIGH CHANCE FOR NOW. ANOTHER SYSTEM IS PROGGED TO AFFECT THE RGN DURING THE THU-FRI TIME FRAME. THIS SYSTEM MAY PULL SOME WARMER AIR INTO THE RGN... RESULTING IN PCPN TYPE ISSUES. FOR NOW...WILL KEEP THINGS SIMPLE AND JUST MENTION A CHC OF SNOW. && .AVIATION...NE WINDS ARE GENERATING LIGHT LAKE EFFECT SNOW SHOWERS NEAR GRB...WHICH WILL HELP TO MAINTAIN THE IFR/MVFR VSBYS/CIGS THROUGH THE EVENING. OTHERWISE...STILL SOME LINGERING LOW CLOUDS ACROSS THE REMAINING TAF SITES...AND CIGS WILL BOUNCE AROUND BETWEEN VFR/MVFR THROUGH THE NIGHT. CIGS WILL BEGIN TO LOWER TOMORROW AFTERNOON AS THE NEXT STORM SYSTEM ARRIVES. VSBYS WITHIN THE SNOW FROM THE STORM WILL FALL TO IFR/LIFR LEVELS. && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 3 PM SATURDAY TO 6 PM CST SUNDAY FOR WIZ011>013-020>022-038>040-048>050-073-074. WINTER WEATHER ADVISORY FROM 12 PM SATURDAY TO 6 PM CST SUNDAY FOR WIZ018-019-030-031-035>037-045. WINTER WEATHER ADVISORY FROM 12 PM SATURDAY TO MIDNIGHT CST SUNDAY NIGHT FOR WIZ005-010. && $$ MPC/KIECKBUSCH wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 219 PM CST FRI DEC 19 2008 .UPDATE...NOTE TO MEDIA - NEW HEADLINES FOR THIS WEEKEND CAN BE FOUND BELOW. OPTED FOR WINTER WX ADVISORIES INSTEAD OF A WATCH AT THIS TIME. LOOKS LIKE 4-6 INCH ACCUMS SOUTH...6 TO 8 INCHES NORTH (WITH UP TO 10 INCHES IN THE LK SUP SNOW BELT) OVER A 24-30 HOUR PERIOD...WITH SOME BLOWING AND DRIFTING AT THE TAIL END OF THE EVENT. MORE DETAILS TO FOLLOW LATER. KIECKBUSCH && .PREV DISCUSSION...ISSUED AT 1047 AM CST FRI DEC 19 2008... UPDATE...13Z SURFACE AND RUC ANALYSIS...AND LATEST IR/WV/RADAR IMAGERY SHOW A VIGOROUS SHORTWAVE IS DRIVING A SURFACE LOW ACROSS CENTRAL INDIANA AND OHIO. MODERATE TO HEAVY SNOWFALL ASSOCIATED WITH 850-700MB FGEN ON THE NORTHERN PERIPHERY OF THE SHORTWAVE IS BEGINNING TO PULL OUT OF THE FOX VALLEY...WHILE LIGHTER 1 1/2-4SM SNOWS CONTINUE TO OUR FAR WESTERN CWA. TIMING TOOL PEGS THE BACK EDGE OF THE DEFORMATION ZONE CURRENTLY ACROSS THE WESTERN PART OF THE STATE TO REACH THE FOX VALLEY BY NOON. ONCE THIS BACK EDGE MOVES THROUGH...WIDESPREAD SNOWS WILL LIGHTEN AND TURN MORE SHOWERY...SIMILAR TO WHATS OCCURRING FARTHER SW NEAR LACROSSE AND SOUTHERN MINNESOTA. THEREFORE...ANTICIPATE TO BEGIN TRIMMING HEADLINES ACROSS THE SW FORECAST AREA OVER THE NEXT HOUR. POINTS FROM THE FOX VALLEY AND POINTS EAST WILL SEE SNOW INTENSITY GRADUALLY DIMINISH OVER THE NEXT ONE TO TWO HOURS AS WELL...BUT WILL STILL HAVE SOME LAKE ENHANCEMENT TO CAUSE 1-2 INCHES THROUGH EARLY AFTERNOON. NEW ZONE UPDATES AND HEADLINE CANCELLATIONS OUT SHORTLY. MPC DISCUSSION ISSUED AT 412 AM CST FRI DEC 19 2008... SHORT TERM...TODAY THROUGH SATURDAY. MAJOR FOCUS OF THE FORECAST ON ONGOING SYSTEM AND HEADLINES. MADE ONE CHANGE TO DOWNGRADE WARNING TO ADVISORY FOR NORTHERN TIER OF COUNTIES. LEFT ADVISORY IN TACK TO THE NORTH...THOUGH LOWERED AMOUNTS. WITH SNOW EXPECTED DURING MORNING COMMUTE...DID NOT WANT TO DROP TOTALLY. STORM SYSTEM NOW OVER NORTHERN MO...WITH BEST PRESSURE FALLS OVER CENTRAL IL/IN. MODEL FORECASTS FOR TRACK LOOK GOOD...QUICKLY MOVING SYSTEM THROUGH CENTRAL IL INTO THE OHIO VALLEY BY NOON. SIG DYNAMICS WITH UPPER SYSTEM/JET THROUGH 12Z...THEN MOVES OFF EAST. SATELLITE AND RADAR TRENDS SHOW HEAVIEST SNOW OVER SOUTHERN WI...WITH REPORTS OF 1 TO 2 INCH HOUR RATES. HEAVIER SNOW NOW LIFTING NORTH INTO WAUTOMA AND OSHKOSH AREAS...WITH SPOTTER IN WAUTOMA AREA REPORTING VISBY DOWN TO 500 FT. SPEED OF SYSTEM AND TIME TO SATURATE COLUMN LIMITING FACTOR FOR SNOW AMOUNTS FURTHER NORTH. WILL NEED TO WATCH...CONVECTIVE AREA OVER IA ASSOCIATED WITH UPPER WAVE. KEPT IDEA OF HEAVIER AMOUNTS OVER THE LAKESHORE WITH SOME LAKE ENHANCEMENT...GIVEN EASTERLY DIRECTION OF LOW LEVEL WINDS. MODEL SOUNDINGS SHOW DELTA T`S CONDITIONAL WITH LAKE BASED CAPES NOT TOO IMPRESSIVE...SO WILL MENTION SCATTERED WORDING WITH LIMITED ACCUMULATION THIS AFTERNOON AND EVENING...WITH LES. WINDS GO LIGHT LATE THIS EVENING AS HIGH PRESSURE WORKS IN...ENDING LES THREAT. NEXT SYSTEM/INVERTED TROF TO BRING MORE ACCUMULATING SNOWS TO THE AREA BY SATURDAY AFTERNOON. LONG TERM...SAT NGT THRU NXT THU. MAIN FCST CHALLENGE REMAINS EXTENT OF SNOW POTENTIAL LTR THIS WEEKEND AND AGAIN EARLY NXT WEEK. TEMPS APR TO STAY BLO NORMAL THRU MUCH OF THE FCST PERIOD. STG CLOSED UPR LOW DIVES SE INTO THE WRN GREAT LKS RGN SAT NGT AS THE INVERTED SFC TROF ROTATES NEWD ACROSS WI. THERE IS STILL SOME QSTN AS TO HOW MUCH INTENSIFICATION THE SFC LOW WL TAKE AS IT LIFTS NE TOWARD THE ERN GREAT LKS BY 12Z SUNDAY. MDLS CONT TO INDICATE STG ISEN LIFT...STG FORCING (ESP Q-G) AND STEEP MID-LVL LAPSE RATES CONSIDERING IT IS LATE DECEMBER. HEADLINES ARE A FOREGONE CONCLUSION...HOWEVER WITH CURRENT STORM IN THE AREA AND AFT COLLABORATION WITH SURROUNDING OFFICES...PREFER TO LET DAYSHIFT HANDLE THE NEW HEADLINES. EXPECT THE SFC LOW TO DEEPEN OVR THE ERN GREAT LKS ON SUNDAY AS THE CLOSED UPR LOW JOINS UP AND THE SYSTEM BECOMES ALMOST VERTICALLY STACKED. EVEN THO STRONGER FORCING SHIFTS EAST... CYCLONIC FLOW REMAIN OVR NE WI...THUS SNOW WITH ADDL ACCUMULATIONS APR LIKELY THRU AT LEAST SUNDAY MORNING. THERE IS ALSO POTENTIAL FOR LK EFFECT ENHANCEMENT OVR NRN WI AS WNDS BACK TO THE N-NW DURING THE DAY. 8H TEMPS DROP TO AROUND -17C...DELTA-T VALUES REACH 20 AND LK-INDUCED CAPES REACH CLOSE TO 400 J/KG. THIS COULD EASILY ADD ANOTHER COUPLE INCHES OF SNOW TO FAVORED AREAS OF VILAS CNTY. ANOTHER THING TO WATCH ON SUNDAY WL BE THE BLUSTERY CONDITIONS ACROSS THE FCST AREA WHICH WL CREATE BLOWING AND DRIFTING OF THE NEW SNOW. ONSET OF CAA WL LIMIT DIURNAL RISE IN TEMPS AND HAVE LEANED TOWARD THE COLDER MAV GUID AS A RESULT. SYNOPTIC SNOW SHOULD BE OVR WITH BY SUNDAY EVENING...LEAVING LINGERING LK EFFECT SNOW SHWRS FOR N-CNTRL WI. MAY NEED TO RAISE POPS FOR VILAS CNTY AS POTENTIAL EXISTS FOR ANOTHER INCH OR TWO BEFORE DRIER AIR ARRIVES LTR SUNDAY NGT AND WNDS BACK ENUF SUCH THAT BETTER SNOW SHWR ACTIVITY STAYS NORTH OF THE MI BORDER. THE REST OF NE WI TO REMAIN DRY BUT RATHER COLD AS 8H TEMPS HOVER AROUND -16C. MIN TEMPS WL DEPEND ON HOW MUCH CLDS BREAK UP WITH THE FRESH SNOW CVR. PREV VALUES MAY BE TOO COLD ESP IF CLDS HANG TOUGH AND HAVE RAISED VALUES A COUPLE OF DEGS. A RDG OF HI PRES BUILDS INTO THE GREAT LKS ON MON AND SHOULD PROVIDE FOR SOME SUNSHINE AND LESS WND. AIRMASS OVR WI STILL RATHER COLD AND HAVE KEPT TEMPS BLO THE MEX GUID. THAT BEING SAID...EXPECT THE SUN TO AT LEAST TRY AND ADD A FEW DEGS TO THE TEMPS. HAVE ADDED A COUPLE OF DEGS TO THE PREV FCST. THE SFC RDG QUICKLY DEPARTS TOWARD THE ERN GREAT LKS MON NGT AND ALLOWS WNDS TO BACK TO A MORE SOUTHERLY DIRECTION. A NEW SHRTWV TROF IS PROGGED TO MOV ACROSS THE ROCKIES WITH LEE-SIDE CYCLOGENESIS DEVELOPING OVR SE CO. LOOK FOR CLDS TO QUICKLY RETURN TO NE WI MON NGT WITH TEMPS DROPPING EARLY AND THEN BECMG STEADY OVRNGT. QSTNS REMAIN AS TO THE AMT OF DIGGING THIS SHRTWV TROF TAKES ON DURING THE DAY TUE. GFS AND CANADIAN DIG THE TROF TOWARD THE SRN PLAINS WHICH KEEPS THE SFC LOW OVR THE CNTRL PLAINS. THE ECMWF SWINGS THE SHRTWV TROF NEWD TOWARD THE UPR MIDWEST WITH THE SFC LOW STRENGTHENING OVR THE NRN PLAINS. SUCH VAST DIFFERENCES PREVENT ME FROM MAKING ANY CHGS TO TUE`S FCST AND HAVE KEPT A CHC OF LGT SNOW DUE TO INCREASING ISEN LIFT. TUE NGT INTO WED`S FCST TO BE DETERMINED BY WHERE THE SHRTWV TROF GOES (LIFTS NE OR DIGS EVEN FARTHER SOUTH TOWARD TX). A WEAKER SYSTEM WOULD ALLOW THE SFC LOW TO TRACK UP THE OHIO RIVER VALLEY WHILE A STRONGER SYSTEM WOULD KEEP THE SFC LOW MORE TOWARD THE TN VALLEY. HAVE KEPT SML CHC POPS GOING FOR TUE NGT AND MAY NEED TO ADD POPS ON WED IN LTR FCSTS IF THE NRN TRACK ENDS UP CORRECT. HI PRESS EXPECTED TO BUILD INTO THE RGN FOR THU AND KEEP THE WEATHER QUIET OVR NE WI. AVIATION...LIFR/VLIFR CONDITIONS IN HEAVY SNOW AT GRB WILL IMPROVE BY MIDDAY AS THE BACK EDGE OF THE SNOW SHIELD SHIFTS EAST. STILL SOME LIGHTER SNOW OUT WITH IFR VSBYS ALL THE WAY OUT TO THE MN/WI BORDER WHICH WILL IMPACT THE TAF SITES OCCASIONALLY FOR MUCH OF THE AFTERNOON. MOIST EAST TO SOUTHEAST FLOW WILL KEEP THE CLOUDS AROUND FOR MUCH OF THE NIGHT...PRIMARILY VFR...BUT COULD BRIEFLY REACH MVFR AT GRB CLOSER TO LAKE MICHIGAN. THE NEXT SYSTEM WILL APPROACH TOMORROW AFTERNOON. MPC && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 3 PM SATURDAY TO 6 PM CST SUNDAY FOR WIZ011>013-020>022-038>040-048>050-073-074. WINTER WEATHER ADVISORY FROM 12 PM SATURDAY TO 6 PM CST SUNDAY FOR WIZ018-019-030-031-035>037-045. WINTER WEATHER ADVISORY FROM 12 PM SATURDAY TO MIDNIGHT CST SUNDAY NIGHT FOR WIZ005-010. && $$ wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 1047 AM CST FRI DEC 19 2008 .UPDATE...13Z SURFACE AND RUC ANALYSIS...AND LATEST IR/WV/RADAR IMAGERY SHOW A VIGOROUS SHORTWAVE IS DRIVING A SURFACE LOW ACROSS CENTRAL INDIANA AND OHIO. MODERATE TO HEAVY SNOWFALL ASSOCIATED WITH 850-700MB FGEN ON THE NORTHERN PERIPHERY OF THE SHORTWAVE IS BEGINNING TO PULL OUT OF THE FOX VALLEY...WHILE LIGHTER 1 1/2-4SM SNOWS CONTINUE TO OUR FAR WESTERN CWA. TIMING TOOL PEGS THE BACK EDGE OF THE DEFORMATION ZONE CURRENTLY ACROSS THE WESTERN PART OF THE STATE TO REACH THE FOX VALLEY BY NOON. ONCE THIS BACK EDGE MOVES THROUGH...WIDESPREAD SNOWS WILL LIGHTEN AND TURN MORE SHOWERY...SIMILAR TO WHATS OCCURRING FARTHER SW NEAR LACROSSE AND SOUTHERN MINNESOTA. THEREFORE...ANTICIPATE TO BEGIN TRIMMING HEADLINES ACROSS THE SW FORECAST AREA OVER THE NEXT HOUR. POINTS FROM THE FOX VALLEY AND POINTS EAST WILL SEE SNOW INTENSITY GRADUALLY DIMINISH OVER THE NEXT ONE TO TWO HOURS AS WELL...BUT WILL STILL HAVE SOME LAKE ENHANCEMENT TO CAUSE 1-2 INCHES THROUGH EARLY AFTERNOON. NEW ZONE UPDATES AND HEADLINE CANCELLATIONS OUT SHORTLY. MPC && .PREV DISCUSSION...ISSUED AT 412 AM CST FRI DEC 19 2008... SHORT TERM...TODAY THROUGH SATURDAY. MAJOR FOCUS OF THE FORECAST ON ONGOING SYSTEM AND HEADLINES. MADE ONE CHANGE TO DOWNGRADE WARNING TO ADVISORY FOR NORTHERN TIER OF COUNTIES. LEFT ADVISORY IN TACK TO THE NORTH...THOUGH LOWERED AMOUNTS. WITH SNOW EXPECTED DURING MORNING COMMUTE...DID NOT WANT TO DROP TOTALLY. STORM SYSTEM NOW OVER NORTHERN MO...WITH BEST PRESSURE FALLS OVER CENTRAL IL/IN. MODEL FORECASTS FOR TRACK LOOK GOOD...QUICKLY MOVING SYSTEM THROUGH CENTRAL IL INTO THE OHIO VALLEY BY NOON. SIG DYNAMICS WITH UPPER SYSTEM/JET THROUGH 12Z...THEN MOVES OFF EAST. SATELLITE AND RADAR TRENDS SHOW HEAVIEST SNOW OVER SOUTHERN WI...WITH REPORTS OF 1 TO 2 INCH HOUR RATES. HEAVIER SNOW NOW LIFTING NORTH INTO WAUTOMA AND OSHKOSH AREAS...WITH SPOTTER IN WAUTOMA AREA REPORTING VISBY DOWN TO 500 FT. SPEED OF SYSTEM AND TIME TO SATURATE COLUMN LIMITING FACTOR FOR SNOW AMOUNTS FURTHER NORTH. WILL NEED TO WATCH...CONVECTIVE AREA OVER IA ASSOCIATED WITH UPPER WAVE. KEPT IDEA OF HEAVIER AMOUNTS OVER THE LAKESHORE WITH SOME LAKE ENHANCEMENT...GIVEN EASTERLY DIRECTION OF LOW LEVEL WINDS. MODEL SOUNDINGS SHOW DELTA T`S CONDITIONAL WITH LAKE BASED CAPES NOT TOO IMPRESSIVE...SO WILL MENTION SCATTERED WORDING WITH LIMITED ACCUMULATION THIS AFTERNOON AND EVENING...WITH LES. WINDS GO LIGHT LATE THIS EVENING AS HIGH PRESSURE WORKS IN...ENDING LES THREAT. NEXT SYSTEM/INVERTED TROF TO BRING MORE ACCUMULATING SNOWS TO THE AREA BY SATURDAY AFTERNOON. LONG TERM...SAT NGT THRU NXT THU. MAIN FCST CHALLENGE REMAINS EXTENT OF SNOW POTENTIAL LTR THIS WEEKEND AND AGAIN EARLY NXT WEEK. TEMPS APR TO STAY BLO NORMAL THRU MUCH OF THE FCST PERIOD. STG CLOSED UPR LOW DIVES SE INTO THE WRN GREAT LKS RGN SAT NGT AS THE INVERTED SFC TROF ROTATES NEWD ACROSS WI. THERE IS STILL SOME QSTN AS TO HOW MUCH INTENSIFICATION THE SFC LOW WL TAKE AS IT LIFTS NE TOWARD THE ERN GREAT LKS BY 12Z SUNDAY. MDLS CONT TO INDICATE STG ISEN LIFT...STG FORCING (ESP Q-G) AND STEEP MID-LVL LAPSE RATES CONSIDERING IT IS LATE DECEMBER. HEADLINES ARE A FOREGONE CONCLUSION...HOWEVER WITH CURRENT STORM IN THE AREA AND AFT COLLABORATION WITH SURROUNDING OFFICES...PREFER TO LET DAYSHIFT HANDLE THE NEW HEADLINES. EXPECT THE SFC LOW TO DEEPEN OVR THE ERN GREAT LKS ON SUNDAY AS THE CLOSED UPR LOW JOINS UP AND THE SYSTEM BECOMES ALMOST VERTICALLY STACKED. EVEN THO STRONGER FORCING SHIFTS EAST... CYCLONIC FLOW REMAIN OVR NE WI...THUS SNOW WITH ADDL ACCUMULATIONS APR LIKELY THRU AT LEAST SUNDAY MORNING. THERE IS ALSO POTENTIAL FOR LK EFFECT ENHANCEMENT OVR NRN WI AS WNDS BACK TO THE N-NW DURING THE DAY. 8H TEMPS DROP TO AROUND -17C...DELTA-T VALUES REACH 20 AND LK-INDUCED CAPES REACH CLOSE TO 400 J/KG. THIS COULD EASILY ADD ANOTHER COUPLE INCHES OF SNOW TO FAVORED AREAS OF VILAS CNTY. ANOTHER THING TO WATCH ON SUNDAY WL BE THE BLUSTERY CONDITIONS ACROSS THE FCST AREA WHICH WL CREATE BLOWING AND DRIFTING OF THE NEW SNOW. ONSET OF CAA WL LIMIT DIURNAL RISE IN TEMPS AND HAVE LEANED TOWARD THE COLDER MAV GUID AS A RESULT. SYNOPTIC SNOW SHOULD BE OVR WITH BY SUNDAY EVENING...LEAVING LINGERING LK EFFECT SNOW SHWRS FOR N-CNTRL WI. MAY NEED TO RAISE POPS FOR VILAS CNTY AS POTENTIAL EXISTS FOR ANOTHER INCH OR TWO BEFORE DRIER AIR ARRIVES LTR SUNDAY NGT AND WNDS BACK ENUF SUCH THAT BETTER SNOW SHWR ACTIVITY STAYS NORTH OF THE MI BORDER. THE REST OF NE WI TO REMAIN DRY BUT RATHER COLD AS 8H TEMPS HOVER AROUND -16C. MIN TEMPS WL DEPEND ON HOW MUCH CLDS BREAK UP WITH THE FRESH SNOW CVR. PREV VALUES MAY BE TOO COLD ESP IF CLDS HANG TOUGH AND HAVE RAISED VALUES A COUPLE OF DEGS. A RDG OF HI PRES BUILDS INTO THE GREAT LKS ON MON AND SHOULD PROVIDE FOR SOME SUNSHINE AND LESS WND. AIRMASS OVR WI STILL RATHER COLD AND HAVE KEPT TEMPS BLO THE MEX GUID. THAT BEING SAID...EXPECT THE SUN TO AT LEAST TRY AND ADD A FEW DEGS TO THE TEMPS. HAVE ADDED A COUPLE OF DEGS TO THE PREV FCST. THE SFC RDG QUICKLY DEPARTS TOWARD THE ERN GREAT LKS MON NGT AND ALLOWS WNDS TO BACK TO A MORE SOUTHERLY DIRECTION. A NEW SHRTWV TROF IS PROGGED TO MOV ACROSS THE ROCKIES WITH LEE-SIDE CYCLOGENESIS DEVELOPING OVR SE CO. LOOK FOR CLDS TO QUICKLY RETURN TO NE WI MON NGT WITH TEMPS DROPPING EARLY AND THEN BECMG STEADY OVRNGT. QSTNS REMAIN AS TO THE AMT OF DIGGING THIS SHRTWV TROF TAKES ON DURING THE DAY TUE. GFS AND CANADIAN DIG THE TROF TOWARD THE SRN PLAINS WHICH KEEPS THE SFC LOW OVR THE CNTRL PLAINS. THE ECMWF SWINGS THE SHRTWV TROF NEWD TOWARD THE UPR MIDWEST WITH THE SFC LOW STRENGTHENING OVR THE NRN PLAINS. SUCH VAST DIFFERENCES PREVENT ME FROM MAKING ANY CHGS TO TUE`S FCST AND HAVE KEPT A CHC OF LGT SNOW DUE TO INCREASING ISEN LIFT. TUE NGT INTO WED`S FCST TO BE DETERMINED BY WHERE THE SHRTWV TROF GOES (LIFTS NE OR DIGS EVEN FARTHER SOUTH TOWARD TX). A WEAKER SYSTEM WOULD ALLOW THE SFC LOW TO TRACK UP THE OHIO RIVER VALLEY WHILE A STRONGER SYSTEM WOULD KEEP THE SFC LOW MORE TOWARD THE TN VALLEY. HAVE KEPT SML CHC POPS GOING FOR TUE NGT AND MAY NEED TO ADD POPS ON WED IN LTR FCSTS IF THE NRN TRACK ENDS UP CORRECT. HI PRESS EXPECTED TO BUILD INTO THE RGN FOR THU AND KEEP THE WEATHER QUIET OVR NE WI. AVIATION...LIFR/VLIFR CONDITIONS IN HEAVY SNOW AT GRB WILL IMPROVE BY MIDDAY AS THE BACK EDGE OF THE SNOW SHIELD SHIFTS EAST. STILL SOME LIGHTER SNOW OUT WITH IFR VSBYS ALL THE WAY OUT TO THE MN/WI BORDER WHICH WILL IMPACT THE TAF SITES OCCASIONALLY FOR MUCH OF THE AFTERNOON. MOIST EAST TO SOUTHEAST FLOW WILL KEEP THE CLOUDS AROUND FOR MUCH OF THE NIGHT...PRIMARILY VFR...BUT COULD BRIEFLY REACH MVFR AT GRB CLOSER TO LAKE MICHIGAN. THE NEXT SYSTEM WILL APPROACH TOMORROW AFTERNOON. MPC && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 6 PM CST THIS AFTERNOON FOR WIZ040- 045-048>050. WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR WIZ020>022-031-037>039-073-074. && $$ wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 406 AM EST SUN DEC 21 2008 .SHORT TERM... TODAY THROUGH MONDAY NIGHT. ...BITTER WIND CHILLS...LAKE EFFECT SNOWSHOWERS AND INCREASING THREAT FOR POWER OUTAGES CONTINUE TO LOOM... ARCTIC COLD FRONT MAKING GOOD PROGRESS WITH TEMPS PLUMMETING BEHIND IT. MOST LOCATIONS GOING FROM MIDDLE 20S TO THE SINGLE DIGITS WITHIN 3 HOURS. ALSO BURST OF STRONGER WIND GUSTS ASSOCIATED WITH THE STG CAA WITH GUSTS IN THE 30 TO 35 KT RANGE. HAS BEEN SOME DISCUSSION ON WIND ADVISORIES FROM SURROUNDING OFFICES...BUT THINK FOR NOW WILL HOLD OFF ON ANYTHING. IF WE CAN GET SOME SUN THIS AFTERNOON AND ALLOW FOR SOME MIXING...COULD BE LOOKING AT THE NEED FOR ONE FOR THE AFTERNOON AND EVE HOURS. WILL DEFER TO DAY SHIFT TO MONITOR. HAVE LOWERED HIGHS TODAY TO BETTER REFLECT THE PUSH OF COLD AIR. STARTING AT 12Z ANTICIPATING TEMPS TO BE WELL INTO THE SINGLE DIGITS WEST TO MID TEENS EAST AS FRONT WILL JUST BE CLEARING THESE AREAS. THEN TEMPS WILL CONTINUE TO SLOWLY FALL. POPULATED WITH RUC40 DATA WHICH SEEMS TO HAVE A GOOD HANDLE ON TRENDS...WHICH WOULD PUT SOME LOCATIONS IN THE SW AREAS NEAR OR EVEN BELOW ZERO BY LATE MORNING. GIVEN UPSTREAM TEMPS ALREADY 1 ABOVE AT ORD AND CORE OF COLDEST 850 MB TEMPS POISED TO PASS OVER THE SW HALF THIS AFTERNOON WITH VALUES IN THE -25 TO -28 C RANGE /15 TO 20 DEGREES BELOW MEANS FOR DECEMBER/...THINK THIS IS REASONABLE AND GRIDS REFLECT THIS. THIS BRINGS ANOTHER CHALLENGE. IF WINDS DO REMAIN UP...THEN THESE SAME AREAS WILL APPROACH OR EXCEED WIND CHILL WARNING CRITERIA. FOR NOW WILL STICK WITH ADVISORY...BUT SPEED UP ONSET TO START WITH PACKAGE RELEASE AND LET DAY SHIFT MONITOR WINDS AND TEMPS FOR POSSIBLE UPGRADE. ALSO HAS HAS BEEN NOTED IN MANY PRODUCTS...ANTICIPATING INCREASED ISSUES WITH POWER OUTAGES AND TREE/POWER LINE DAMAGE AS STRONG WINDS OVERLOAD ALREADY BURDENED LINES AND TREES. POWER HAS ALREADY BEEN FLUCTUATING HERE AT THE OFFICE AND EXPECT THIS TO CONTINUE FOR MANY AREAS WITH ICE STILL AROUND. LAKE EFFECT SNOWSHOWERS WILL QUICKLY KICK IN BEHIND THE FRONT WITH THE BULK OF THE ACTIVITY ACROSS THE FAR NORTHERN PARTS OF THE AREA. WILL CONTINUE WITH WINTER STORM WARNING FOR BERRIEN THROUGH ST JOE COUNTIES IN MICHIGAN. WHILE BEING A BIT OF A PROLONGED EVENT...WIND CHILLS...WINDS...TEMPS AND SNOWFALL WILL ALL LEAD TO ROUGH TRAVEL IN THESE AREAS. BAND STILL LOOKS TO SET UP RATHER NICELY TOWARDS MONDAY MORNING ACROSS THE FAR SOUTHER MICHIGAN COUNTIES AND SINCE THIS HAS BEEN THERE FOR SEVERAL RUNS WILL BLEND WITH GRR AND DTX AND EXPAND LIKELY POPS OUT INTO HILLSDALE CO. WILL KEEP AMOUNTS IN THE 1 TO 2 INCH RANGE IN THESE AREAS FOR NOW. THINGS LOOK TO EASE UP FOR MONDAY AND MONDAY NIGHT TO GIVE A DRY BUT COLD FORECAST BEFORE THE NEXT SYSTEM ARRIVES IN THE LONG TERM. && .LONG TERM... DIFFICULT FCST PD THROUGHOUT. VRY INTENSE SW TROUGH OVR THE GULF OF AK YDA HAS STEAMED SEWD TO NR COASTAL WA STATE THIS MORNING...BRINGING RARE HEAVY SNOW TO KSEA AND A GOOD INDICATOR OF HOW INTENSE THIS SYS IS. UPSTREAM JET STREAK PER VAPOR LOOKS QUITE INTENSE AS WELL AND WILL AID SYS DIG INTO SWRN ROCKIES TUE. DOWNSTREAM CONDS REMAIN A MESS THOUGH W/INCOMING INTENSE ARCTIC WEDGE AND EVENTUALLY STG LL MSTR RTN OVERTOP RETREATING COLD DOME MID WEEK. 00Z GUIDANCE TAKEN AS A WHOLE TRENDING QUICKER W/PCPN DVLPMNT AND NOW INDICATING SNOW TUE AM AND SEE NO REASON TO ARGUE GIVEN UPR JET SHIFTING THROUGH THE NRN LAKES BY TUE AFTN. PRIMARY DIFFICULTY LIES W/LL THERMAL RESPONSE INTO RETREATING ARCTIC WEDGE. AS NOTED YDA...STILL FEEL MODELS ERODING ARCTIC DOME TOO QUICKLY ESP OVR DEEPER HIGH DENSITY SNOWPACK ACRS NRN PORTION OF CWA YET ON THE OTHER HAND CAN`T DISCOUNT LACK OF SNOW CVR ACRS DOWNSTATE IL/IN. THUS IT SEEMS AT LEAST THE THREAT FOR ANOTHER POTENTIALLY SIG ICING EVENT PSBL TUE NIGHT AND WED ACRS NRN/NW THIRD OF CWA. PRIOR TO THAT...MAINLY SNOW TUE INTO TUE EVENING BFR WARM LYR LEADS TO IP MIX GENERALLY SOUTH OF US 30 AND ZR SOUTH OF US 24. EJECTION OF INTENSE WRN SW LT TUE MORE DISCONCERTING GIVEN DRAMATIC MED RANGE TRENDS W/DEGREE OF SFC DVLPMNT SEEN IN 00Z GFS AND ITS ENSEMBLES. OP GFS/ECMWF SOLUTIONS SIMILAR...BOTH IN INTENSITY AND QUICKER NEWD EJECTION COMPARED W/GFS ENSEMBLES YET CERTAINLY WITHIN THE SCOPE OF POSSIBILITIES. PRIOR FLAT OPEN WV EJECTION SEEN IN 12Z RUNS COMPARABLE W/LATEST WRF 4KM RUN SO UNCERTAINTY IS HIGH. BEST RECOURSE AT THIS POINT IS TO WEIGHT WED PD MORE HEAVILY TWD A MIXED PCPN EVENT XPC PERHAPS FAR NW PER IMPLIED SFC LOW TRACK BUT DO XPC ADDNL SIG FLUCTUATIONS THROUGH THE NXT 36HRS UNTIL THIS SYS GETS FURTHER INTO UPR AIR NETWORK AND SAMPLED BTR. IN THE LEAST...ANOTHER HEAVY PRECIPITATION EVENT LIKELY TO BE REALIZED TUE NIGHT/WED. AFT THAT...PATTN RELOADS AMAZINGLY FAST W/YET ANOTHER INTENSE MID LAT CYCLONE FOR LT WEEK. ADDNL HEADACHES CERTAIN YET WILL SPARE ANY DETAILS FOR THE MOMENT GIVEN THAT TIME RANGE. && .PREV DISCUSSION... /ISSUED 1230 AM EST SUN DEC 21 2008/ AVIATION... 06Z TAFS. TAFS OVERALL IN GOOD SHAPE WITH ARRIVAL OF STG COLD FRONT INTO KSBN SOMETIME AROUND 7Z AND KFWA A FEW HOURS LATER. QUICK INCREASE IN WINDS BEHIND THE FRONT WITH GUSTS IN THE 25 TO 35 KT RANGE COMMON. EXPECTED BURST OF SOMEWHAT HEAVIER SNOW NOW MOVING KSBN AND WILL CLIP KFWA AS WELL. AFTER THAT MAINLY BLOWING SNOW AND ON AND OFF SNOW SHOWERS TO PREVAIL UNTIL MORNING WHEN THINGS TRANSITION TO MORE LAKE EFFECT AND FOCUS TO NEAR OR NORTH OF KSBN. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ MONDAY FOR INZ003>009-012>018-020-022>027-032>034. MI...WIND CHILL ADVISORY UNTIL 1 PM EST MONDAY FOR MIZ080-081. WINTER STORM WARNING UNTIL 10 AM EST MONDAY FOR MIZ077>079. OH...WIND CHILL ADVISORY UNTIL 1 PM EST MONDAY FOR OHZ001-002-004-005- 015-016-024-025. LM...HEAVY FREEZING SPRAY WARNING UNTIL 5 AM EST MONDAY FOR LMZ043- 046. GALE WARNING UNTIL 5 AM EST MONDAY FOR LMZ043-046. && $$ SHORT TERM...FISHER LONG TERM...HOLSTEN AVIATION...FISHER in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 300 AM EST SUN DEC 21 2008 .DISCUSSION... MAIN PROBLEM FOR THE SHORT TERM WILL BE THE WINDS AND TEMPERATURES. VERY STRONG LOW PRESSURE OVER SOUTHERN OHIO MOVING EAST. EXTREMELY TIGHT PRESSURE AND TEMPERATURE GRADIENT MOVING INTO INDIANA. AT INDY HAD A WIND GUST TO 43 MPH AT 130 AM. RUC HAS 48 MPH WINDS AT 2,500 FT THIS AFTERNOON. WITH A GOOD AMOUNT OF SUNSHINE ESPECIALLY DURING THE MORNING THERE WILL BE GOOD MIXING. THIS WILL KEEP WINDS ABOVE ADVISORY LEVELS CENTRAL AND N AND CLOSE ENOUGH IN THE SOUTH. THE WINDS WILL DROP DOWN AFTER SUNSET. ALL OF THE MODELS ARE WAY TO WARM WITH THE TEMPS. THE NAM WHICH IS THE COLDEST AT HUF AT 09Z HAS 20 THEY WILL BE 16 OR MAYBE LOWER. THE NAM 850 MB TEMPS DROP TO -25 THIS AFTERNOON. SO HAVE CUT GUIDANCE HIGHS WAY BACK TODAY. THEY MAY TRY TO REBOUND SOME THIS AFTERNOON BUT WITH COLD AIR SC MOVING IN THIS WILL SLOW THAT ALONG WITH THE SHORTEST PERIOD OF SUNSHINE OF THE YEAR. THIS WILL PUT WIND CHILL VALUES WELL INTO ADVSRY LEVELS. EVEN THOUGH WINDS WILL DECREASE THIS EVENING THEY WILL REMAIN HIGH ENOUGH WITH THE TEMPS JUST ABOVE ZERO TO KEEP THE ADVSRY GOING THROUGH 12Z MONDAY. THE WEDGE OF EXTREMELY COLD AIR WILL MOVE EAST OF INDIANA ON MONDAY. THIS ALONG WITH AT LEAST PARTLY SUNNY WILL ALLOW TEMPS TO REBOUND BUT HIGHS WILL STILL REMAIN IN THE TEENS. MODEL TIME SECS FAVOR SOME CLRG ON MON AS LOW LVL MOISTURE THINS AND SFC HIGH PRES SETTLES ACRS THE OH VLY ALONG WITH A FLAT UPR RIDGE. NICE RETURN FLOW ON TUESDAY AHEAD OF AN APRCHG CD FNT SHOULD BRING SOME LGT SN IN TUES PM AND CHRISTMAS EVE PERHAPS MIXED WITH RN S PER SOUNDINGS AND CRITICAL THICKNESS PROGS. MODELS SUGGESTING MORE PRECIP IN THE EXTENDED THAN EITHER HPC OR THIS MRNGS FCST. GFS AND ECMWF HAVE A LOT OF DIFFERENCES BUT ARE TRENDING TOWARD A PROLONGED PD OF RETURN FLOW AHEAD OF A SLOW MOVING CD FNT. SO...OVERRUNNING SECENARIO PSBL WITH RN/SN MIX SUGGESTED BY THICKNESSES. LEANED A LITTLE MORE TOWARDS THE USUALLY MORE ACCURATE ECMWF AND HAVE PRECIP IN ON CHRISTMAS NGT && .AVIATION... DISCUSSION FOR 06Z TAFS. CHALLENGING FCST IS BECOMING MORE CLEAR CUT AS OF MIDNIGHT. ARCTIC COLD FRONT WILL SWEEP THROUGH ALL TAF SITES BY 06Z WITH GUSTY WEST WINDS AND IMPROVING VIS CONDS INTO THE MVFR RANGE AND EVENTUALLY TO VFR BY 08Z. CIGS WILL ALSO IMPROVE TO VFR WITH UNRESTRICTED CIGS EXPECTED QUICKLY FROM WEST TO EAST THROUGH 09Z. MODEL GUIDANCE APPEARS TOO HIGH WITH RH FCSTS IN THE LOWEST 5KFT FEET WHEN COMPARED TO REALITY ON SATELLITE. AS A RESULT...WE WILL KEEP VFR CIGS IN THE FCST INTO SUNDAY. I DO EXPECT SOME STRATOCU TO RE-DEVELOP AFTER SUNRISE BUT AS MENTIONED WE WILL KEEP VFR CIGS. GUSTY WNW WINDS WILL PERSIST WITH GUSTS AOA 30KTS EXPECTED. && .IND WATCHES/WARNINGS/ADVISORIES... ...WIND ADVISORY FROM 7AM TO 7PM SUNDAY... ...WIND CHILL ADVISORY IN EFFECT FROM 7 AM SUNDAY TO 7 AM EST MONDAY... && $$ AVIATION...LJ PUBLIC...SH in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1040 PM MST SAT DEC 20 2008 .DISCUSSION... 230 PM MST SAT DEC 20 2008 THE 20Z SURFACE ANALYSIS HAS HIGH PRESSURE OVER THE CENTRAL AND NORTHERN PLAINS. VISIBLE SATELLITE SHOWING SOME CLOUDS OVER THE FORECAST AREA WITH MORE UPSTREAM. WATER VAPOR IMAGERY INDICATES A DISTURBANCE MOVING SOUTHEAST TOWARD NORTHWEST KANSAS. UPPER FLOW WILL BE NORTHWEST TONIGHT AND SUNDAY AS A RIDGE BUILDS INTO THE ROCKIES. THE RIDGE MOVES EAST OF THE ROCKIES AND ACROSS THE NORTHERN PLAINS WITH ZONAL FLOW ACROSS THE CENTRAL PLAINS. SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE CENTRAL PLAINS TONIGHT AND SUNDAY. THE HIGH WILL DRIFT EAST ON MONDAY FOLLOWED BY A TROUGH OVER EASTERN COLORADO. THE TROUGH WILL MOVE EAST TUESDAY NIGHT. THE MAIN FORECAST ISSUES ARE TEMPERATURES AND WIND CHILL POTENTIAL AS WELL AS POPS FOR TONIGHT AND TUESDAY. ADDED A SLIGHT CHANCE OF LIGHT SNOW TONIGHT ACROSS THE NORTHERN ZONES DUE TO A SHORTWAVE CURRENTLY OVER SOUTHWEST COLORADO WHICH WILL MOVE THROUGH DURING THE LATE EVENING AND OVERNIGHT. THE BEST MOISTURE IS OVER THE NORTH BUT CANNOT RULE OUT AT LEAST FLURRIES SOUTH OF THAT AREA. FORCING AND MOISTURE APPEARS TO DECREASE AFTER 06Z SO WILL LEAVE FLURRIES OUT OF THE EASTERN ZONES. FOR THE SNOW EVENT ON TUESDAY...DECIDED TO ADD A SMALL AREA OF SLIGHT CHANCE POPS OVER THE NORTHWEST ZONES. TIMING OF THE FRONT AND MOISTURE SHOULD PROVIDE AT LEAST A SLIGHT CHANCE THERE AFTER 06Z TUESDAY. OTHERWISE TUESDAY EVENT STILL LOOKS ON TRACK BUT LEFT POPS AT SLIGHT CHANCE. BY TUESDAY NIGHT THE SHORTWAVE LIFTS OUT LEAVING SUBSIDENCE OVER THE FORECAST AREA. PLAN TO HAVE A SMALL AREA OF FLURRIES OVER THE FAR SOUTH ZONES OTHERWISE WILL REMOVE POPS. ALL OTHER PERIODS...SUNDAY THROUGH MONDAY EVENING WILL BE DRY WITH NIL POPS DUE TO SUBSIDENCE. WIND CHILL VALUES ARE IN QUESTION DUE TO WIND SPEED BEHIND THE EXITING SHORTWAVE SUNDAY MORNING. AT THE WORST WIND SPEEDS WILL BE ABOUT 12 MPH OR JUST ABOVE THE CRITERIA FOR A FEW HOURS JUST BEFORE AND AFTER SUNRISE. HOWEVER WIND SPEEDS MAY BE LOWER IF THE GFS WINDS ARE RIGHT. LOWER WINDS ARE ALSO SUPPORTED BY THE RUC. THERE MAY BE A FEW HOURS AROUND 12Z WHERE WIND CHILLS WILL BE BORDERLINE OR JUST ABOVE CRITERIA. THE POTENTIAL GOES AWAY QUICKLY AFTER 12Z. TEMPERATURES TONIGHT SHOULD BE HELD UP SOME BY INCREASING CLOUDS AS THE NEXT SHORTWAVE APPROACHES. MINS ARE FORECAST NEAR OR JUST BELOW ZERO. BY SUNDAY NIGHT RETURN FLOW WILL HELP BRING SOME WARMER AIR BACK TO THE FORECAST AREA. LOWS SHOULD STAY ABOVE ZERO WITH SINGLE DIGIT READINGS. MINS WILL CONTINUE TO WARM MONDAY NIGHT WITH INCREASING CLOUDS. READINGS SHOULD BE IN THE TEENS. TUESDAY NIGHT LOWS WILL FALL BACK INTO THE UPPER SINGLE DIGITS WITH SOME POSSIBLE SNOW ON THE GROUND. DAYTIME HIGH TEMPERATURES SHOULD WARM INTO THE TEENS SUNDAY WARMING TO THE 20S MONDAY/TUESDAY. IN THE EXTENDED...(WEDNESDAY THROUGH SATURDAY)...WESTERLY FLOW WILL DOMINATE THIS FORECAST. HOWEVER THERE ARE SOME MAJOR DIFFERENCES BETWEEN THE GFS AND THE ECMWF BY FRIDAY NIGHT/SATURDAY. THE GFS BRINGS AN UPPER LOW INTO A FAVORABLE POSITION FOR A WINTER STORM WHILE THE EUROPEAN TAKES AN OPEN TROUGH ACROSS THE NORTHERN PLAINS WITH ZONAL FLOW ACROSS THE CENTRAL PLAINS. FOR NOW WILL KEEP THE FORECAST DRY AND WAIT FOR FURTHER MODEL RUNS TO GET RESOLUTION ON THIS. MAX TEMPERATURES WILL WARM BACK INTO ABOVE NORMAL 40S WITH ZONAL FLOW DOMINATING. MINS WILL RISE BACK TO A FEW DEGREES ABOVE NORMAL WITH READINGS IN THE UPPER TEENS/LOW 20S. FS && .AVIATION... 1040 PM MST SAT DEC 20 2008 FOR THE 06Z TAFS...VFR WILL PREVAIL THROUGH THE PERIOD WITH LIGHT AND VARIABLE WINDS THROUGH EARLY MORNING. AN AREA OF LIGHT SNOW DEVELOPED AS ANTICIPATED WITH TRANSIENT MVFR AT KGLD AROUND 05Z. LOW CIGS WILL CONTINUE TO TRANSLATE SOUTHEAST AWAY FROM KGLD/KMCK TAF SITES AFTER 06-07Z. A SECONDARY CONCERN REMAINS PATCHY FOG DEVELOPING IN THE KMCK AREA TOWARD SUNRISE AS ARCTIC HIGH PRESSURE BUILDS INTO THE REGION. DEWPOINT TEMPERATURES UPSTREAM REMAIN LARGE LATE THIS EVENING LEADING TO LOW CONFIDENCE IN VISIBILITY CROSSING FLIGHT RULE CATEGORY THRESHOLDS AT KMCK WITH NO INCLUSION AT THIS TIME. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ ks AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1235 AM EST SUN DEC 21 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAFS .UPDATE... SNOW HAS SPREAD INTO THE SOUTH AND WRN CWA. DRY AIR ABOVE H9 EVIDENT ON EVENING TAMDAR AT ESC AND ON THE 00Z RAOB AT APX IS LEADING TO JUST FLURRIES IN THE EAST. DESPITE PERISISTENT VSBY 1-2SM...SNOW HAS ONLY ADDED UP TO 2 INCHES AT THE MOST FOR THE SOUTH. THUS FAR... LOOKS LIKE LOWER SNOW RATIOS...10-15:1...ARE LIMITING SNOW AMOUNTS. ENHANCEMENT OFF LK MICHIGAN MAY STILL IMPACT NRN MEMOMINEE INTO DELTA COUNTY...BUT WITH LOW SNOW RATIOS AND LACK OF A CONVERGENCE AREA SETTING UP YET...DID NOT EMPHASIZE REAL HEAVY SNOW FOR THOSE AREAS AND KEPT ADVY GOING. SPOTTER REPORT FM KEWEENAW EARLIER THIS EVENING DID INDICATE A FLUFFIER SNOW IS OCCURRING THERE. OVERALL...DO TO THE LOWER SNOW RATIOS AND LESS QPF PROGGED THAN EARLIER...LOWERED SNOW AMOUNTS FOR THE OVERNIGHT AROUND AN INCH MOST SPOTS. DID NOT ALTER SNOW AMOUNTS FOR AREAS WHERE ESE WINDS PROVIDE POTENTIAL LAKE CONTRIBUTION (KEWEENAW AND SOUTH CNTRL). THOSE SPOTS COULD STILL SEE NIGHTTIME ACCUMS UP TO 5 INCHES. LOW TEMPS OCCURRED EARLIER THIS EVENING AND TEMPS HAVE NOW BECOME STEADY OR WILL RISE THROUGH THE NIGHT. NO SIG CHANGES TO SUNDAY OR SUNDAY NIGHT. SIGNIFICANT BAND OF HEAVIER SNOW/WITH SFC TROUGH PASSAGE STILL ON TRACK TO COME ACROSS KEWEENAW IN THE MORNING...THEN INTO THE REST OF THE LK SUPERIOR ZONES LATE MORNING/EARLY AFTN. AFTER THAT...FOCUSED HEAVIEST SNOW IN THE AFTN OVR FAR WEST AS BETTER DEEP MOISTURE IS PRESENT WITH CYCLONIC NRLY FLOW AND H85 TEMPS NEAR -18C. SOME MID LEVEL DRYING MAY KNOCK DOWN SNOW OVR THE CNTRL SLIGHTLY. STRONG WINDS (30-35 KNOTS IN THE MIXED LAYER) WILL BLOW AND DRIFT SNOW SIGNIFICANTLY SUNDAY AFTN INTO SUNDAY EVENING. CURRENT FORECAST LOOKS FINE IN THIS REGARD. UPDATED WSW AND ZFP ARE OUT. && .SYNOPSIS... WATER VAPOR IMAGE AND RUC SHOWING A CLOSED LOW OVER NORTHWEST NORTH DAKOTA...PUSHING A RIDGE OVER WESTERN ONTARIO AND THE UPPER GREAT LAKES REGIONS. WEAK SHORTWAVES ARE BEING EJECTED OUT AHEAD OF THIS LOW AND ARE OVER MANITOBA AND MINNESOTA. SURFACE ANALYSIS DEPICTS AN INVERTED TROUGH STRETCHING FROM WESTERN IOWA NORTH INTO SOUTHEAST MANITOBA. THIS TROUGH IS SEPARATING A RIDGE OVER EASTERN ONTARIO FROM A HIGH OVER SOUTHWEST CANADA. ANOTHER SIGNIFICANT LOW IS OVER THE MIDDLE MISSISSIPPI RIVER VALLEY. A STATIONARY FRONT STRETCHES EAST FROM THIS LOW ACROSS THE SOUTHEASTERN STATES. && .SHORT TERM...TONIGHT AND SUNDAY. STRONG LIFT PER 700-500MB Q-VECTOR DIVERGENCE AND DEEP MOISTURE THROUGH 20KFT THIS EVENING WILL ALLOW FOR 3 TO 4 INCHES OF SYNOPTIC SNOW TO FALL TONIGHT AS INVERTED TROUGH SHIFTS INTO FORECAST AREA AFTER 00Z. MAIN SNOW WON`T ARRIVE UNTIL AFT 00Z. A SURFACE LOW EJECTING OUT OF TEXAS THIS AFTERNOON WILL MERGE WITH THE TROUGH OVER THE LOWER GREAT LAKES SUNDAY MORNING. AS THIS HAPPENS THE RESULTING NORTHEASTERLY FLOW WILL ALLOW FOR HEAVY LES TO DEVELOP OVER NORTH CENTRAL AND WESTERN UPPER MICHIGAN. WINTER STORM WARNINGS REMAIN IN EFFECT FOR GOGEBIC/ONTONAGON/MARQUETTE/ALGER. ADVISORIES WILL KEEP ELSEWHERE AS NOT ENOUGH CONFIDENCE IN REACHING WARNING CRITERIA. TONIGHT THROUGH SUNDAY UP TO 8 INCHES OR MORE OF LES MAY FALL ACROSS THE HIGHER TERRAIN OF MARQUETTE COUNTY...AREAS OF KEWEENAW COUNTY AND INTO WESTERN GOGEBIC/ONTONAGON COUNTIES. THIS IS FURTHER SUPPORTED BY THE LOCAL WRF MODEL. CONCERN ABOUT POSSIBLE LAKE ENHANCED SNOW SHOWERS OVER MENOMINEE COUNTY...FOR POSSIBLE NEED FOR WARNING. HOWEVER...WRF/NAM12 SHOWING WINDS BACKING NORTH SHORTLY AFTER SUNRISE OVER SOUTHERN COUNTIES...DRIER AIR ADVECTING IN...AND LACK OF TERRAIN SUPPORT OF LES. THUS WILL STAY WITH THE CURRENT ADVISORIES FOR THAT AREA TOO. AFTER COORDINATED WITH GRB DECIDED TO STAY WITH THE ADVISORY FOR NOW. && .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY. SUN NIGHT...EXPECT TRANSITION FROM LAKE ENHANCED TO LAKE EFFECT SNOW WITH CONTINUED VERY FAVORABLE SNOW GROWTH PARAMETERS WITH GOOD UPWARD MOTION IN THE DGZ THROUGH 06Z/MON. EVEN THOUGH SNOW/WATER RATIOS SHOULD BE AOA 30/1 DURING THE EVENING...WITH CONTINUED WINDY CONDITIONS...FRACTURING AND DRIFTING SHOULD REDUCE ACTUAL/OBSERVED SNOW TOTALS. NEVERTHELESS...ADDITIONAL AMOUNTS IN THE 2 TO 6 INCH RANGE ARE EXPECTED FOR N WIND FAVORED SNOWBELTS...WITH THE GREATEST AMOUNTS IN THE HIGHER TERRAIN WHERE STRONG UPSLOPE LIFT WILL OCCUR. OVERNIGHT...WITH BACKING WINDS...LOWERING INVERSION HEIGHTS/ EXIT OF DEEPER MOISTURE...SNOWFALL RATES WILL TAPER OFF AND LES SHOULD SHIFT TOWARD NW FLOW FAVORED AREAS. BLOWING SNOW SHOULD ALSO SUBSIDE OVERNIGHT AS THE GRADIENT WEAKENS IN THE WAKE OF THE DEPARTING LOW. AS WINDS BACK TO WRLY BY MIDDAY MON...LES WILL SHIFT INTO THE KEWEENAW AND FAR NE UPPER MI WHILE RELATIVELY TRANQUIL WEATHER PREVAILS ACROSS THE REST OF THE CWA. BEFORE CLOUDS THICKEN MON NIGHT IN ADVANCE OF THE NEXT SHRTWV...TEMPS MAY PLUMMET CLOSER TO LOWER NAM GUIDANCE VALUES NEAR -10F WELL INLAND. TUE...MDLS WERE IN GOOD AGREEMENT WITH THE NEXT MID LEVEL AND SFC TROUGH THAT WILL MOVE THROUGH THE REGION BRINGING ANOTHER ROUND OF SNOW. MDLS TEMP/UVV/RH PROFILE SUGGEST SNOW/WATER MAY BE RELATIVELY LOW WITH BEST LIFT ABOVE THE DGZ. SO WITH QPF VALUES IN THE 0.10 TO 0.20 RANGE AND SNOW/WATER RATIOS NEAR 15/1 ACCUMULATIONS MAINLY IN THE 1 TO 3 INCH RANGE WOULD BE EXPECTED. WED...SIGNIFICANT UNCERTAINTY REMAINS WITH THE POTENTIAL FOR ANOTHER STRONGER SHRTWV AND SFC LOW DEVELOPMENT. THE 12Z ECMWF AND UKMET FAVORED POTENTIAL FOR HEAVIER SNOW WITH THIS FEATURE WHILE THE GFS AND CMC DID NOT. IF THE EURO MODELS VERIFY...ANOTHER HEAVY SNOW EVENT WOULD BE EXPECTED WITH FAVORABLE SCENARIO FOR LAKE ENHANCED SNOW IN N CNTRL UPPER MI. THU-SAT...THE FCST GENERALLY FOLLOWED THE HPC PREFERRED ECMWF/CMC MDLS SCENARIO WHICH ALSO HAD DECENT SUPPORT FROM THE 12Z GFS ENSEMBLES. THE 06Z/12Z WAS AN OUTLIER IN BRINGING A WEAKER NRN STREAM SYSTEM THROUGH THE NRN TIER AND DELAYING THE EJECTION OF A STRONGER SHRTWV FROM THE SW CONUS. SO...WITH A SW FLOW PATTERN AND STRONGER SE CONUS RIDGE...A SHRTWV AND SFC LOW TRACK THROUGH OR WEST OF CNTRL UPPER MI COULD BRING POTENTIAL FOR MIXED PCPN (SN/FZRA/PL/RA) AND A BRIEF WARMUP AOA FREEZING BY LATE FRI. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... SNOW WILL CONTINUE TO IMPACT BOTH SITES TONIGHT AS UPPER DISTURBANCE AND SURFACE TROUGH PUSH THROUGH AREA. EXPECT IFR VSBY/CIGS WITH THE SNOW. PERIOD OF HEAVIER SNOW/POTENTIAL VLIFR CONDITIONS DEVELOPS AROUND 12Z AT CMX AS THE SFC TROUGH SHIFTS THROUGH...THEN BY LATE SUNDAY MORNING AT SAW. IN THE WAKE OF THE HEAVY SNOW THROUGH SUNDAY AFTN/EVENING...EXPECT VLIFR/LIFR CONDITIONS AT BOTH SITE DUE TO LK EFFECT SNOW...STRONG NRLY WINDS GUSTING TO 35 KNOTS...AND SIGNIFICANT BLOWING SNOW. CONDITIONS WILL BEGIN TO IMPROVE AT SAW AND CMX BY LATE SUNDAY EVENING WITH THE ARRIVAL OF DRIER AIR AND DIMINISHING WINDS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... THE WINDS ON LAKE SUPERIOR WILL INCREASE TONIGHT OUT OF THE NORTHEAST. THIS IS DUE TO INTERACTION BETWEEN THE RIDGE OF HIGH PRESSURE REMAINING OVER NORTHERN ONTARIO...AND A LOW PRESSURE OVER THE OHIO RIVER VALLEY. WINDS SHOULD INCREASE FURTHER ON SUNDAY TO NORTH WINDS 25 TO 30 KNOTS WITH FREQUENT GALE FORCE GUSTS TO 35 OR 40 KT AS THE LOW CONTINUES TO DEEPEN AND COLD AIR RUSHES SOUTH OUT OF CANADA. THIS COLD AIR WILL ALSO HELP PRODUCE HEAVY FREEZING SPRAY. THE WINDS WILL GRADUALLY DIMINISH SUNDAY NIGHT AND GALE FORCE GUSTS WILL DIMINISH AS THE LOW PULLS AWAY. THE HIGH PRESSURE RIDGE WILL CROSS UPPER MICHIGAN LATE MONDAY INTO MONDAY NIGHT...BUT WINDS ON SUPERIOR SHOULD STILL STAY WEST TO SOUTHWEST AT 15 TO 30 KNOTS. A LOW PRESSURE SYSTEM WILL DEVELOP OVER THE CENTRAL PLAINS ON TUESDAY AND MOVE INTO THE UPPER GREAT LAKES TUESDAY NIGHT AND WEDNESDAY. WINDS SHOULD STAY BELOW GALES CRITERIA WITH THIS SYSTEM...THOUGH THE SOUTHERLY WINDS AHEAD OF IT ON TUESDAY AND THE NORTHWEST WINDS BEHIND ON IT ON WEDNESDAY WILL CONTINUE TO RANGE FROM 15 TO 30 KNOTS. && UPPER MICHIGAN... WINTER WEATHER ADVISORY THROUGH 7 AM EST MONDAY FOR MIZ004-013-084. WINTER WEATHER ADVISORY FROM 1 AM SUNDAY TO 7 AM EST MONDAY FOR MIZ007-014-085. WINTER STORM WARNING THROUGH 1 AM EST MONDAY FOR MIZ001-003. WINTER STORM WARNING THROUGH 7 AM EST /6 AM CST/ MONDAY FOR MIZ002-009. WINTER STORM WARNING FROM 1 AM SUNDAY TO 7 AM EST MONDAY FOR MIZ005-006. WINTER WEATHER ADVISORY THROUGH 6 PM CST SUNDAY FOR MIZ010>012. LAKE SUPERIOR... GALE WARNING FROM 11 AM SUNDAY TO MIDNIGHT EST SUNDAY NIGHT FOR LSZ265>267. GALE WARNING FROM 7 AM TO 11 PM EST SUNDAY FOR LSZ263-264. GALE WARNING FROM 1 PM SUNDAY TO MIDNIGHT EST SUNDAY NIGHT FOR LSZ248>251. GALE WARNING FROM 10 AM TO 11 PM EST SUNDAY FOR LSZ242>245. GALE WARNING FROM 7 AM EST /6 AM CST/ TO 4 PM EST /3 PM CST/ SUNDAY FOR LSZ162. HEAVY FREEZING SPRAY WARNING FROM 7 AM EST /6 AM CST/ SUNDAY TO 7 AM EST /6 AM CST/ MONDAY FOR LSZ162-263-264. LAKE MICHIGAN... GALE WARNING LATE SUNDAY AFTERNOON INTO SUNDAY EVENING FOR LMZ221-250. && $$ UPDATE...JLA SYNOPSIS/SHORT TERM...DLG LONG TERM...JLB AVIATION...JLA MARINE...DLG mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1135 PM EST SAT DEC 20 2008 .UPDATE... SNOW HAS SPREAD INTO THE SOUTH AND WRN CWA. DRY AIR ABOVE H9 EVIDENT ON EVENING TAMDAR AT ESC AND ON THE 00Z RAOB AT APX IS LEADING TO JUST FLURRIES IN THE EAST. DESPITE PERISISTENT VSBY 1-2SM...SNOW HAS ONLY ADDED UP TO 2 INCHES AT THE MOST FOR THE SOUTH. THUS FAR... LOOKS LIKE LOWER SNOW RATIOS...10-15:1...ARE LIMITING SNOW AMOUNTS. ENHANCEMENT OFF LK MICHIGAN MAY STILL IMPACT NRN MEMOMINEE INTO DELTA COUNTY...BUT WITH LOW SNOW RATIOS AND LACK OF A CONVERGENCE AREA SETTING UP YET...DID NOT EMPHASIZE REAL HEAVY SNOW FOR THOSE AREAS AND KEPT ADVY GOING. SPOTTER REPORT FM KEWEENAW EARLIER THIS EVENING DID INDICATE A FLUFFIER SNOW IS OCCURRING THERE. OVERALL...DO TO THE LOWER SNOW RATIOS AND LESS QPF PROGGED THAN EARLIER...LOWERED SNOW AMOUNTS FOR THE OVERNIGHT AROUND AN INCH MOST SPOTS. DID NOT ALTER SNOW AMOUNTS FOR AREAS WHERE ESE WINDS PROVIDE POTENTIAL LAKE CONTRIBUTION (KEWEENAW AND SOUTH CNTRL). THOSE SPOTS COULD STILL SEE NIGHTTIME ACCUMS UP TO 5 INCHES. LOW TEMPS OCCURRED EARLIER THIS EVENING AND TEMPS HAVE NOW BECOME STEADY OR WILL RISE THROUGH THE NIGHT. NO SIG CHANGES TO SUNDAY OR SUNDAY NIGHT. SIGNIFICANT BAND OF HEAVIER SNOW/WITH SFC TROUGH PASSAGE STILL ON TRACK TO COME ACROSS KEWEENAW IN THE MORNING...THEN INTO THE REST OF THE LK SUPERIOR ZONES LATE MORNING/EARLY AFTN. AFTER THAT...FOCUSED HEAVIEST SNOW IN THE AFTN OVR FAR WEST AS BETTER DEEP MOISTURE IS PRESENT WITH CYCLONIC NRLY FLOW AND H85 TEMPS NEAR -18C. SOME MID LEVEL DRYING MAY KNOCK DOWN SNOW OVR THE CNTRL SLIGHTLY. STRONG WINDS (30-35 KNOTS IN THE MIXED LAYER) WILL BLOW AND DRIFT SNOW SIGNIFICANTLY SUNDAY AFTN INTO SUNDAY EVENING. CURRENT FORECAST LOOKS FINE IN THIS REGARD. UPDATED WSW AND ZFP ARE OUT. && .SYNOPSIS... WATER VAPOR IMAGE AND RUC SHOWING A CLOSED LOW OVER NORTHWEST NORTH DAKOTA...PUSHING A RIDGE OVER WESTERN ONTARIO AND THE UPPER GREAT LAKES REGIONS. WEAK SHORTWAVES ARE BEING EJECTED OUT AHEAD OF THIS LOW AND ARE OVER MANITOBA AND MINNESOTA. SURFACE ANALYSIS DEPICTS AN INVERTED TROUGH STRETCHING FROM WESTERN IOWA NORTH INTO SOUTHEAST MANITOBA. THIS TROUGH IS SEPARATING A RIDGE OVER EASTERN ONTARIO FROM A HIGH OVER SOUTHWEST CANADA. ANOTHER SIGNIFICANT LOW IS OVER THE MIDDLE MISSISSIPPI RIVER VALLEY. A STATIONARY FRONT STRETCHES EAST FROM THIS LOW ACROSS THE SOUTHEASTERN STATES. && .SHORT TERM...TONIGHT AND SUNDAY. STRONG LIFT PER 700-500MB Q-VECTOR DIVERGENCE AND DEEP MOISTURE THROUGH 20KFT THIS EVENING WILL ALLOW FOR 3 TO 4 INCHES OF SYNOPTIC SNOW TO FALL TONIGHT AS INVERTED TROUGH SHIFTS INTO FORECAST AREA AFTER 00Z. MAIN SNOW WON`T ARRIVE UNTIL AFT 00Z. A SURFACE LOW EJECTING OUT OF TEXAS THIS AFTERNOON WILL MERGE WITH THE TROUGH OVER THE LOWER GREAT LAKES SUNDAY MORNING. AS THIS HAPPENS THE RESULTING NORTHEASTERLY FLOW WILL ALLOW FOR HEAVY LES TO DEVELOP OVER NORTH CENTRAL AND WESTERN UPPER MICHIGAN. WINTER STORM WARNINGS REMAIN IN EFFECT FOR GOGEBIC/ONTONAGON/MARQUETTE/ALGER. ADVISORIES WILL KEEP ELSEWHERE AS NOT ENOUGH CONFIDENCE IN REACHING WARNING CRITERIA. TONIGHT THROUGH SUNDAY UP TO 8 INCHES OR MORE OF LES MAY FALL ACROSS THE HIGHER TERRAIN OF MARQUETTE COUNTY...AREAS OF KEWEENAW COUNTY AND INTO WESTERN GOGEBIC/ONTONAGON COUNTIES. THIS IS FURTHER SUPPORTED BY THE LOCAL WRF MODEL. CONCERN ABOUT POSSIBLE LAKE ENHANCED SNOW SHOWERS OVER MENOMINEE COUNTY...FOR POSSIBLE NEED FOR WARNING. HOWEVER...WRF/NAM12 SHOWING WINDS BACKING NORTH SHORTLY AFTER SUNRISE OVER SOUTHERN COUNTIES...DRIER AIR ADVECTING IN...AND LACK OF TERRAIN SUPPORT OF LES. THUS WILL STAY WITH THE CURRENT ADVISORIES FOR THAT AREA TOO. AFTER COORDINATED WITH GRB DECIDED TO STAY WITH THE ADVISORY FOR NOW. && .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY. SUN NIGHT...EXPECT TRANSITION FROM LAKE ENHANCED TO LAKE EFFECT SNOW WITH CONTINUED VERY FAVORABLE SNOW GROWTH PARAMETERS WITH GOOD UPWARD MOTION IN THE DGZ THROUGH 06Z/MON. EVEN THOUGH SNOW/WATER RATIOS SHOULD BE AOA 30/1 DURING THE EVENING...WITH CONTINUED WINDY CONDITIONS...FRACTURING AND DRIFTING SHOULD REDUCE ACTUAL/OBSERVED SNOW TOTALS. NEVERTHELESS...ADDITIONAL AMOUNTS IN THE 2 TO 6 INCH RANGE ARE EXPECTED FOR N WIND FAVORED SNOWBELTS...WITH THE GREATEST AMOUNTS IN THE HIGHER TERRAIN WHERE STRONG UPSLOPE LIFT WILL OCCUR. OVERNIGHT...WITH BACKING WINDS...LOWERING INVERSION HEIGHTS/ EXIT OF DEEPER MOISTURE...SNOWFALL RATES WILL TAPER OFF AND LES SHOULD SHIFT TOWARD NW FLOW FAVORED AREAS. BLOWING SNOW SHOULD ALSO SUBSIDE OVERNIGHT AS THE GRADIENT WEAKENS IN THE WAKE OF THE DEPARTING LOW. AS WINDS BACK TO WRLY BY MIDDAY MON...LES WILL SHIFT INTO THE KEWEENAW AND FAR NE UPPER MI WHILE RELATIVELY TRANQUIL WEATHER PREVAILS ACROSS THE REST OF THE CWA. BEFORE CLOUDS THICKEN MON NIGHT IN ADVANCE OF THE NEXT SHRTWV...TEMPS MAY PLUMMET CLOSER TO LOWER NAM GUIDANCE VALUES NEAR -10F WELL INLAND. TUE...MDLS WERE IN GOOD AGREEMENT WITH THE NEXT MID LEVEL AND SFC TROUGH THAT WILL MOVE THROUGH THE REGION BRINGING ANOTHER ROUND OF SNOW. MDLS TEMP/UVV/RH PROFILE SUGGEST SNOW/WATER MAY BE RELATIVELY LOW WITH BEST LIFT ABOVE THE DGZ. SO WITH QPF VALUES IN THE 0.10 TO 0.20 RANGE AND SNOW/WATER RATIOS NEAR 15/1 ACCUMULATIONS MAINLY IN THE 1 TO 3 INCH RANGE WOULD BE EXPECTED. WED...SIGNIFICANT UNCERTAINTY REMAINS WITH THE POTENTIAL FOR ANOTHER STRONGER SHRTWV AND SFC LOW DEVELOPMENT. THE 12Z ECMWF AND UKMET FAVORED POTENTIAL FOR HEAVIER SNOW WITH THIS FEATURE WHILE THE GFS AND CMC DID NOT. IF THE EURO MODELS VERIFY...ANOTHER HEAVY SNOW EVENT WOULD BE EXPECTED WITH FAVORABLE SCENARIO FOR LAKE ENHANCED SNOW IN N CNTRL UPPER MI. THU-SAT...THE FCST GENERALLY FOLLOWED THE HPC PREFERRED ECMWF/CMC MDLS SCENARIO WHICH ALSO HAD DECENT SUPPORT FROM THE 12Z GFS ENSEMBLES. THE 06Z/12Z WAS AN OUTLIER IN BRINGING A WEAKER NRN STREAM SYSTEM THROUGH THE NRN TIER AND DELAYING THE EJECTION OF A STRONGER SHRTWV FROM THE SW CONUS. SO...WITH A SW FLOW PATTERN AND STRONGER SE CONUS RIDGE...A SHRTWV AND SFC LOW TRACK THROUGH OR WEST OF CNTRL UPPER MI COULD BRING POTENTIAL FOR MIXED PCPN (SN/FZRA/PL/RA) AND A BRIEF WARMUP AOA FREEZING BY LATE FRI. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... SNOW IS SPREADING INTO THE SOUTHERN PORTION OF UPPER MICHIGAN AS UPPER DISTURBANCE AND SURFACE TROUGH PUSH INTO THE AREA. EXPECT LGT SNOW...MOSTLY IFR VSBY/CIGS...TO START UP AT BOTH SITES BY MIDNIGHT. PERIOD OF HEAVIER SNOW/POTENTIAL VLIFR CONDITIONS DEVELOPS LATE TONIGHT AT CMX AS THE SFC TROUGH SHIFTS THROUGH...THEN BY LATE SUNDAY MORNING AT SAW. IN THE WAKE OF THE HEAVY SNOW THROUGH SUNDAY AFTN...EXPECT VLIFR/LIFR CONDITIONS AT BOTH SITE DUE TO LK EFFECT SNOW...STRONG NRLY WINDS GUSTING TO 35 KNOTS...AND SIGNIFICANT BLOWING SNOW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... THE WINDS ON LAKE SUPERIOR WILL INCREASE TONIGHT OUT OF THE NORTHEAST. THIS IS DUE TO INTERACTION BETWEEN THE RIDGE OF HIGH PRESSURE REMAINING OVER NORTHERN ONTARIO...AND A LOW PRESSURE OVER THE OHIO RIVER VALLEY. WINDS SHOULD INCREASE FURTHER ON SUNDAY TO NORTH WINDS 25 TO 30 KNOTS WITH FREQUENT GALE FORCE GUSTS TO 35 OR 40 KT AS THE LOW CONTINUES TO DEEPEN AND COLD AIR RUSHES SOUTH OUT OF CANADA. THIS COLD AIR WILL ALSO HELP PRODUCE HEAVY FREEZING SPRAY. THE WINDS WILL GRADUALLY DIMINISH SUNDAY NIGHT AND GALE FORCE GUSTS WILL DIMINISH AS THE LOW PULLS AWAY. THE HIGH PRESSURE RIDGE WILL CROSS UPPER MICHIGAN LATE MONDAY INTO MONDAY NIGHT...BUT WINDS ON SUPERIOR SHOULD STILL STAY WEST TO SOUTHWEST AT 15 TO 30 KNOTS. A LOW PRESSURE SYSTEM WILL DEVELOP OVER THE CENTRAL PLAINS ON TUESDAY AND MOVE INTO THE UPPER GREAT LAKES TUESDAY NIGHT AND WEDNESDAY. WINDS SHOULD STAY BELOW GALES CRITERIA WITH THIS SYSTEM...THOUGH THE SOUTHERLY WINDS AHEAD OF IT ON TUESDAY AND THE NORTHWEST WINDS BEHIND ON IT ON WEDNESDAY WILL CONTINUE TO RANGE FROM 15 TO 30 KNOTS. && UPPER MICHIGAN... WINTER WEATHER ADVISORY THROUGH 7 AM EST MONDAY FOR MIZ004-013-084. WINTER WEATHER ADVISORY FROM 1 AM SUNDAY TO 7 AM EST MONDAY FOR MIZ007-014-085. WINTER STORM WARNING THROUGH 1 AM EST MONDAY FOR MIZ001-003. WINTER STORM WARNING THROUGH 7 AM EST /6 AM CST/ MONDAY FOR MIZ002-009. WINTER STORM WARNING FROM 1 AM SUNDAY TO 7 AM EST MONDAY FOR MIZ005-006. WINTER WEATHER ADVISORY THROUGH 6 PM CST SUNDAY FOR MIZ010>012. LAKE SUPERIOR... GALE WARNING FROM 11 AM SUNDAY TO MIDNIGHT EST SUNDAY NIGHT FOR LSZ265>267. GALE WARNING FROM 7 AM TO 11 PM EST SUNDAY FOR LSZ263-264. GALE WARNING FROM 1 PM SUNDAY TO MIDNIGHT EST SUNDAY NIGHT FOR LSZ248>251. GALE WARNING FROM 10 AM TO 11 PM EST SUNDAY FOR LSZ242>245. GALE WARNING FROM 7 AM EST /6 AM CST/ TO 4 PM EST /3 PM CST/ SUNDAY FOR LSZ162. HEAVY FREEZING SPRAY WARNING FROM 7 AM EST /6 AM CST/ SUNDAY TO 7 AM EST /6 AM CST/ MONDAY FOR LSZ162-263-264. LAKE MICHIGAN... GALE WARNING LATE SUNDAY AFTERNOON INTO SUNDAY EVENING FOR LMZ221-250. && $$ UPDATE...JLA SYNOPSIS/SHORT TERM...DLG LONG TERM...JLB AVIATION...JLA MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 501 AM EST SUN DEC 21 2008 .SYNOPSIS... STRONG ARCTIC HIGH PRESSURE WILL SETTLE INTO THE CENTRAL U.S. TODAY AND TONIGHT...BRINGING A TIGHT PRESSURE GRADIENT AND AN ARCTIC AIRMASS INTO THE OHIO VALLEY AND GREAT LAKES. THIS HIGH WILL SETTLE OVER THE OHIO VALLEY MONDAY NIGHT AND THEN WILL MOVE QUICKLY EAST OF THE REGION ON TUESDAY. DEVELOPING LOW PRESSURE ACROSS THE PLAINS WILL SURGE AN ABUNDANT AMOUNT OF MOISTURE FROM THE GULF OF MEXICO INTO THE REGION TUESDAY AFTERNOON THROUGH WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... HAVE USED A BLEND OF THE NAM-WRF AND THE LATEST RUC DUE TO THEIR BETTER HANDLING OF THE ARCTIC AIRMASS THAT WILL BE MOVING INTO THE REGION TODAY. MODELS SUGGEST THAT TEMPERATURES WILL TUMBLE ACROSS THE ENTIRE REGION TODAY...WITH THE GREATEST DROP EXPECTED ACROSS THE NW REGION WHERE THE HEART OF THE ARCTIC AIR WILL INFILTRATE FIRST. HIGHS TODAY WILL BE EARLY AND WILL TUMBLE INTO THE SINGLE DIGITS NORTHWEST TO NEAR 20 SOUTHEAST. A TIGHT PRESSURE GRADIENT BETWEEN AN ARCTIC HIGH OVER THE PLAINS AND DEEPENING LOW PRESSURE TO THE NE WILL RESULT IN BLUSTERY TO WINDY CONDITIONS TODAY. WINDS WILL ALSO GUST AROUND 40 MPH AT TIMES. MODEL GUIDANCE AND MIXING SCHEMES SUGGEST REGION WILL BE BORDERLINE WIND ADVISORY AND HAVE OPTED AT THIS TIME TO ISSUE A SPECIAL WX STATEMENT TO COVER THE WINDY CONDITIONS. OF GREATER CONCERN WILL BE THE PLUMMETING WIND CHILL READINGS AND HAVE THUS ISSUED WIND CHILL ADVISORIES FOR THE ENTIRE REGION FOR TODAY THROUGH MONDAY MORNING. WIND CHILL VALUES WILL APPROACH 20 BELOW NORTHWEST TO AROUND 5 BELOW SE. SKY CONDITIONS WILL BE A LITTLE TRICKY TODAY AS LOW LEVEL MOISTURE QUICKLY EXITS THE REGION THROUGH MID MORNING...LEAVING PARTLY TO MOSTLY SUNNY SKIES FOR A PERIOD OF TIME. THEREAFTER...INCREASING RH BETWEEN 925 MB AND 850 MB WILL ENCROACH THE REGION FROM THE NW... ALLOWING STRATOCUMULUS CLOUDS TO FORM AND ADVECT SE. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... AS COLD AIR ADVECTS OVER THE WARMER WATERS OF THE GREAT LAKES REGION AND AS HIGHER LOW LVL RH AIR MOVES SE ACROSS THE REGION...SKIES WILL BECOME MOSTLY CLOUDY TO CLOUDY TONIGHT. SFC PRESSURE GRADIENT WILL REMAIN TIGHT THROUGH THE EARLY MORNING HOURS...SO BLUSTERY TO WINDY CONDITIONS WILL CONTINUE ALONG WITH WIND GUSTS IN THE 30 TO 40 MPH RANGE. HAVE INCLUDED A SLIGHT CHANCE FOR SNOW SHOWERS ALONG AND NORTH OF I-70 DUE TO AN APPROACHING SFC TROF AND WEAK DISTURBANCE ALOFT. HAVE RELIED ON RAW NAM-WRF SFC TEMPERATURES FOR LOWS TONIGHT AS IT SHOULD HANDLE THE COLD ARCTIC AIRMASS BETTER THAN MOS GUIDANCE. LOWS WILL RANGE FROM NEAR 0 NORTH TO THE SINGLE DIGITS SOUTH. A WIND CHILL ADVISORY WILL REMAIN IN EFFECT. ON MONDAY...COLD ARCTIC HIGH PRESSURE WILL BUILD EAST TOWARD THE OHIO VALLEY. MOSTLY CLOUDY SKIES WILL BECOME PARTLY SUNNY FROM SW TO NE THROUGH THE DAY. A FEW SNOW SHOWERS MAY LINGER IN THE MORNING ACRS THE NE. WINDS WILL DIMINISH. WITH TEMPS WARMING INTO THE TEENS TO LOWER 20S BY AFTERNOON...WIND CHILLS WILL RISE ABOVE ADVISORY CRITERIA. HAVE GONE COLDER THAN MAV GUIDANCE DUE TO THE ARCTIC AIRMASS IN PLACE. AS THE ARCTIC HIGH MOVES ACROSS THE OHIO VALLEY REGION TUESDAY EVENING...SKIES WILL BRIEFLY BECOME MOSTLY CLEAR. THEREAFTER...MID AND HIGH CLOUDS WILL BE ON THE INCREASE FROM THE SW AHEAD OF NEXT DEVELOPING WX SYSTEM. FOR TUESDAY INTO TUESDAY NIGHT...LOW PRESSURE WILL DEVELOP ACROSS THE CENTRAL PLAINS. A DEEP SOUTHERLY FLOW WILL DEVELOP BETWEEN THE LOW AND THE DEPARTING ARCTIC HIGH...BRING AN ABUNDANT SURGE OF GULF MOISTURE INTO OUR REGION. MODELS HAVE SPED UP THE TIMING OF PCPN ONSET BY TUESDAY AFTN. WITH THE DEEP SOUTHERLY FLOW...AIR ALOFT WILL WARM MUCH QUICKER THAN AT THE SURFACE. THE RESULT WILL BE THE POTENTIAL FOR A WINTRY MIX ALONG AND NORTH OF THE OHIO RIVER TUESDAY AFTERNOON AND EVENING. THERE COULD BE SOME MINOR SNOW ACCUMULATIONS NW WITH SOME SOME SLEET AND ICE ACCUMULATIONS ELSEWHERE NORTH OF THE RIVER. AS AFOREMENTIONED LOW DEEPENS AND MOVES TOWARD THE MID MS VALLEY BY WEDNESDAY MORNING...SURFACE TEMPS WILL CONTINUE TO WARM AND ALL LOCATIONS SHOULD TURN OVER TO JUST RAIN BY MORNING. MODELS CONTINUE TO HINT AT A DECENT RAINFALL EVENT ALONG THE I-71 CORRIDOR WHERE UP TO AN INCH MAY FALL. THE PROSPECTS FOR A WHITE CHRISTMAS ARE NOT LOOKING GOOD ATTM. LOW PRESSURE WILL MOVE TO THE NW OF THE REGION LATE WEDNESDAY... SWINGING A COLD FRONT ACRS THE AREA WEDNESDAY NIGHT. THIS SCENARIO WILL PUMP WARM AIR INTO THE REGION ON WEDNESDAY WITH SHOWERS AND MILD TEMPERATURES. MODELS INDICATE THAT THE CHANCES FOR A CHANGE OVER TO SNOW ON THE BACK SIDE OF THE FRONT IS MINIMAL AS SUBSIDENCE AND DEEP MOISTURE EXIT QUICKLY AFTER FRONTAL PASSAGE BEFORE TEMPERATURES BECOME COLD ENOUGH TO SUPPORT SNOW. && .LONG TERM /THURSDAY THROUGH SATURDAY/... HIGH PRESSURE WILL PUSH QUICKLY EAST ACROSS THE AREA ON CHRISTMAS DAY PROVIDING FOR A BRIEF BREAK IN THE PCPN. ANOTHER SYSTEM WILL THEN QUICKLY APPROACH FROM THE WEST FOR THE END OF THE WEEK. MODELS VARYING SOME ON STRENGTH AND TIMING OF THIS SYSTEM SO WILL KEEP POPS RELATIVELY LOW. RIGHT NOW...IT LOOKS LIKE WE SHOULD BE WARM ENOUGH TO KEEP ANY PCPN MAINLY RAIN FRIDAY INTO SATURDAY. && .AVIATION /10Z SUNDAY THROUGH THURSDAY/... ARCTIC FRONT RAPIDLY APPCHG TERMINALS FROM THE WEST ERLY THIS MRNG. EXPECT FROPA AT KCVG/KLUK/KDAY BY 07Z...KILN AROUND 08Z AND KCMH/KLCK BTWN 08-09Z. AREAS OF -DZ/-FZDZ AND LIFR CONDITIONS WILL PERSIST AHEAD OF THE BNDRY. ONCE THE FRONT MOVES THRU...VSBYS SHOULD RECOVER QUICKLY TO 5-6SM WITH CIGS LIFTING TO BTWN 500-1000FT. MODEL SOUNDINGS CONTINUE TO INDICATE THE POTENTIAL FOR -FZDZ FOR ABOUT THREE TO FOUR HOURS AFT FROPA. HAVE ELECTED TO LEAVE ANY MENTION OF -FZDZ OUT AFT FROPA AS NOT SEEING MUCH IN WAY OF PCPN IN ANY OBS TO THE WEST. ALSO...AS VERY COLD AND DRY ARCTIC AIRMASS BEGINS TO ADVECT INTO REGION...PROCESSES CONDUCIVE FOR -FZDZ WILL BECOME DISRUPTED. WILL CONTINUE TO MONITOR AND WILL AMEND IF -FZDZ CONTINUES TO BE AN ISSUE LATER IN THE OVERNIGHT. CIGS WILL LIFT ABV 1000FT AT THE WESTERN TERMINALS PRIOR TO DAYBREAK. THE OTHER BIG ISSUE FOR THIS FCST IS THE STRONG WESTERLY WINDS IN WAKE OF THE FROPA. LIKELY TO SEE SUSTAINED NEAR 20KTS AND GUSTS AROUND 30KTS BY DAYBREAK WITH STRONGER WINDS THRU THE DAY. NOW APPEARS THAT SC DECK WILL SCATTER OUT ACRS SRN FCST AREA SUN MRNG WITH POTENTIAL AT AN EXTENDED PERIOD OF MSTLY SUNNY SKIES. THE INCREASED SUNSHINE LIKELY TO PROMOTE STRONGER BNDRY LYR MIXING AND CONSEQUENTLY MAY LEAD TO INCREASES IN SFC WINDS THRU THE AFTN. ALL TERMINALS LIKELY TO SEE SOME SUNSHINE LATER TODAY BUT EXPECT CLOUDS TO BE MORE PREVALENT AT KDAY AND POSSIBLY EVEN AT KCMH AND KLCK WHERE ANY CLEARING WILL BE CONFINED TO A FEW HOURS DURING THE AFTN. POST FRNTL SC DECK WILL REASSERT ITSELF AND SPREAD BACK ACRS THE TERMINALS THIS EVNG AS SHARP MID LVL S/WV SWINGS THRU REGION. CIGS WILL EVENTUALLY LOWER BACK INTO MVFR CAT LATE. WINDS WILL DECREASE TONIGHT BUT REMAIN GUSTY. OUTLOOK...MVFR CEILINGS AND VISIBILITIES POSSIBLE TUESDAY NIGHT AND WEDNESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...WIND CHILL ADVISORY FROM NOON TODAY TO 12 PM EST MONDAY FOR OHZ026-034-035-042>046-051>053-060>062. WIND CHILL ADVISORY FROM 6 PM THIS EVENING TO 10 AM EST MONDAY FOR OHZ054>056-063>065-070>074-077>082-088. KY...WIND CHILL ADVISORY FROM 6 PM THIS EVENING TO 10 AM EST MONDAY FOR KYZ089>100. IN...WIND CHILL ADVISORY FROM NOON TODAY TO 12 PM EST MONDAY FOR INZ050-058-059. WIND CHILL ADVISORY FROM 6 PM THIS EVENING TO 10 AM EST MONDAY FOR INZ066-073>075-080. && $$ SYNOPSIS...HICKMAN NEAR TERM...HICKMAN SHORT TERM...HICKMAN LONG TERM...HICKMAN/JGL AVIATION...RYAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 337 AM CST SUN DEC 21 2008 .SHORT TERM...TODAY THROUGH 00Z WEDNESDAY MAIN FCST CHALLENGES FACING THE NEAR TERM THIS MORNING DEALS WITH BITTERLY COLD WIND CHILLS & SNOWFALL THIS MORNING...AND SNOWFALL POTENTIAL MONDAY EVENING/NIGHT. CURRENTLY MSAS IS SHOWING WEAK FRONTAL BOUNDARY DROPPING THROUGH CWA ATTM...WITH WINDS PICKING UP AS SECONDARY PRESSURE RISE BUBBLE APPROACHES THE AREA. CURRENTLY KABR IS GUSTING TO 30KTS...WITH KPIR GUSTING TO 44KTS. WITH TEMPS CURRENTLY WELL BELOW ZERO...WIND CHILL WARNING CRITERIA HAVING NO TROUBLE BEING MET. AS WRAP-AROUND WAA/TROWEL DROPS BACK INTO THE AREA FROM THE NORTH...ANTICIPATE AN UPTICK IN THE SNOW COVERAGE THIS MORNING. HOWEVER...BY 18Z WAA FINALLY BEGINS TO WANE AS THETA-E FORCING BECOMES MORE NEUTRAL. THE DECISION IS THEN WILL THERE BE ENOUGH LIGHT SNOW TO COUPLE WITH THE STRONG WINDS TO JUSTIFY A HEADLINE FOR THE BLOWING SNOW...OR WILL THE WIND CHILL WARNING TAKE CENTER STAGE? ATTM...WILL CONTINUE WITH WIND CHILL WARNING DUE TO HIGHER PERSONAL DANGER...BUT ADD A MENTION OF BLSN AND RESTRICTED VSBYS TO WSW STATEMENT. ALSO...WITH LATEST RUC SHOWING THAT MAIN PRESSURE RISE AXIS WILL REACH THE ERN CWA BY 18Z THIS AFTERNOON...HAVE OPTED TO EXTEND IN TIME THE WIND CHILL WARNING THROUGH 22Z. LOCAL ABRWRF MODEL SHOWS THAT SFC WINDS WILL FALL RATHER FAST THEREAFTER. CWA THEN CATCHES A BRIEF BREAK...ALBEIT COLD...SUNDAY NIGHT INTO MONDAY AS ARCTIC HIGH PASSES THROUGH THE AREA. MEX GUIDANCE VALUES WERE THE COLDEST...AND HAVE UNDERCUT THAT BY ANOTHER DEGREE OR SO. GIVEN STRENGTH OF HIGH PRESSURE...NO CLOUDS FORECAST TO ADVECT IN UNTIL AFT 12Z MONDAY AND DEEP FRESH SNOW COVER...SHOULD BE PRIME CONDITIONS TO MAXIMIZE RADITIONAL COOLING. FOR MONDAY AFTERNOON THROUGH TUESDAY...NEXT TROF APPROACHES THE CWA. UPPER FLOW TRANSITIONS TO SW AHEAD OF THIS FEATURE...WITH ROBUST WAA MOVING BACK INTO THE REGION. 85H/7H THETA-E FORCING BECOMES PRETTY IMPRESSIVE 00-06Z TIMEFRAME ON TUESDAY...AND 85H-7H Q-VECTOR CONVERGENCE ALSO SHOW RATHER IMPRESSIVE WAA LIFTING INTO THE REGION. BUFKIT SHOWS THAT PRIME SNOW GROWTH REGION MAY BE A TAD HIGH...BUT THERE IS SOME MODEST VALUES OF LIFT THROUGH THE LAYER. HAVE EXPANDED THE AREA OF LIKELY POPS MONDAY NIGHT...AND ALSO GONE WITH A NON-DIURNAL TEMPERATURE TREND MONDAY NIGHT IN ANTICIPATION OF STRONG WAA. AM A BIT WORRIED ABOUT HOW QUICK THE SW PART OF THE CWA WILL MOISTEN UP MONDAY AFTERNOON TO ALLOW FOR PCPN DEVELOPMENT...BUT HAVE INCLUDED SOME SMALL POPS 18Z-00Z MONDAY GIVEN RAPID INCREASE SEEN IN THE 85H-7H LAYER SPEC HUMIDITIES DURING THAT TIME. HAVE ALSO BOLSTERED THE SNOWFALL TOTAL GRID FOR THE 18Z MONDAY THROUGH 12Z WEDNESDAY GRID. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY EXTENDED PERIOD STARTS OFF WITH INVERTED TROUGH AXIS FROM END OF SHORT TERM PERIOD HAVING MOVED EAST INTO MN WITH MOST OF THE PRECIP ALSO HAVING MOVED EAST OF THE AREA. ALTHOUGH...HAVE MAINTAINED SLIGHT CHANCE POPS ACROSS THE EASTERN CWA FOR TUESDAY NIGHT TO ACCOUNT FOR ANY LIGHT SNOW ON THE BACK SIDE OF THIS SYSTEM. HIGH PRESSURE WILL BE SETTLING INTO THE AREA TUESDAY NIGHT INTO WEDNESDAY MORNING WHICH WILL MAKE FOR VERY COLD OVERNIGHT LOWS ONCE AGAIN...WITH TEENS BELOW ZERO QUITE POSSIBLE. AFTER THIS HIGH MOVES OFF TO THE EAST...WAA PATTERN SETS UP FOR THE END OF THE WEEK. GFS STILL HANGING ONTO A WEAK WAVE MOVING ACROSS THE AREA ON THURSDAY WITH VERY LIGHT QPF ACROSS EXTREME EASTERN SOUTH DAKOTA AND INTO MINNESOTA. EC/CANADIAN CONTINUE TO IGNORE THIS FEATURE. LOOKS LIKE POPS HAD BEEN PREVIOUSLY REMOVED FOR THURSDAY AND WILL CONTINUE THIS TREND. TEMPERATURES WILL REMAIN BELOW NORMAL BUT IT APPEARS AS IF THURSDAY WILL BE THE WARMEST DAY OF THE WEEK. WILL BE OPTIMISTIC IN SAYING THE NORTHERN CWA COULD SEE 20 DEGREES WHILE THE SOUTHWESTERN COUNTIES WARM INTO THE MID 20S. && .AVIATION... MVFR/LOW END VFR CIGS WILL CONTINUE ACROSS THE REGION THROUGH THE MORNING HOURS WITH AREAS OF -SN AND BLSN. VSBYS MAY BE REDUCED TO AROUND 1/2 SM TO 1 SM AT TIMES ACROSS KPIR/KABR/KATY TERMINALS. LESS SNOW COVER AT KMBG SHOULD PREVENT VSBYS FROM GETTING THIS LOW. CLOUDS WILL BE ON THE DECREASE DURING THE AFTERNOON HOURS AND WIND SPEEDS WILL ALSO BEGIN TO DECREASE BY LATE AFTERNOON. THIS WILL BRING AN END TO THE BLSN. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WIND CHILL WARNING UNTIL 4 PM CST /3 PM MST/ THIS AFTERNOON FOR BROWN-BUFFALO-CAMPBELL-CLARK-CODINGTON-CORSON-DAY-DEUEL- DEWEY-EDMUNDS-FAULK-GRANT-HAMLIN-HAND-HUGHES-HYDE-JONES- LYMAN-MARSHALL-MCPHERSON-POTTER-ROBERTS-SPINK-STANLEY-SULLY- WALWORTH. MN...WIND CHILL WARNING UNTIL 4 PM CST THIS AFTERNOON FOR BIG STONE- TRAVERSE. && $$ SHORT TERM...HINTZ LONG TERM...TMT AVIATION...TMT WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1040 AM EST SUN DEC 21 2008 ...DANGEROUSLY COLD WIND CHILLS...HEAVY LAKE EFFECT SNOW AND INCREASING THREAT FOR POWER OUTAGES CONTINUE TO LOOM... .UPDATE... SIGNIFICANT CHANGES MADE TO FORECAST THIS MORNING AND ALL PRODUCTS SHOULD BE UPDATED AND OUT. SUBSIDENCE AND VERY DRY AIR ASSOCIATED WITH ARCTIC INTRUSION HAS CLEARED SKIES ACROSS MOST AREAS EXCEPT WHERE LAKE CLOUDS PERSIST. ADDED SUNSHINE SHOULD HELP INCREASE MIXING TO SOME EXTENT IN LOWER LEVELS AND THIS WILL RESULT IN INCREASED WINDS INTO THIS AFTERNOON. EXPECT CLOUDS TO INCREASE AGAIN LATER TODAY. SURFACE GEOSTROPHIC WIND PLOT SHOWING 50 TO 60 KNOTS AT 12Z UPSTREAM TO EASTERN IA AND WESTERN WI. BUFKIT SOUNDINGS WERE SHOWING POTENTIAL OF UP TO 45 KNOTS FROM INVERSION HEIGHT. GIVEN THE ICING SITUATION AND NUMEROUS POWER OUTAGES ALREADY OCCURRING...DECIDED TO UPGRADE TO A WIND ADVISORY MOST AREAS. HOWEVER...CENTRAL AND NORTHERN AREAS WHERE A LIGHT SNOW OCCURRED AND SNOW COVER ALREADY EXISTS...WENT WITH A WINTER WEATHER ADVISORY FOR ADDED IMPACT OF BLOWING SNOW AND POTENTIAL FOR ADDITIONAL SNOWFALL LATER TODAY AND TONIGHT. THIS PRODUCT COMBINES THE WIND THREAT WITH THE BLOWING SNOW FOR SIMPLICITY OF HEADLINES. NEXT FOCUS WAS ON WIND CHILL CRITERIA. AS WE HAVE BEEN INDICATING LAST FEW DAYS...MODELS HAD NO CLUE ON SEVERITY OF THIS COLD AIRMASS AND ONLY COLLABORATION ISSUES KEPT US FROM GOING COLDER. NOW THAT IT IS HERE AND TEMPS ARE WELL BELOW GUIDANCE...UPGRADES ARE NEEDED FROM WIND CHILL ADVISORY TO WARNINGS. SEVERAL SITES ALREADY AT OR BELOW ZERO WITH TEMPERATURES AND CURRENT WINDS CREATING WIND CHILLS AT WARNING CRITERIA NEAR 25 BELOW ZERO. UPGRADED ALL AREAS TO WARNING THROUGH MONDAY MORNING. HIGHER GUSTS THIS AFTERNOON COULD PUSH VALUES COLDER THAN 30 BELOW IN SOME AREAS AS WE ARE NOT EXPECTING MUCH RECOVERY IN TEMPS. WINDS RELAX SOME TONIGHT BUT LOWS BELOW ZERO EXPECTED SO WIND CHILLS SHOULD REMAIN IN WARNING AREA. IT HAS BEEN AWHILE SINCE WE HAVE EXPERIENCED THESE KIND OF WIND CHILLS. WINTER STORM WARNING WAS LEFT INTACT. AGAIN TO KEEP HEADLINES SIMPLE...WIND ADVISORY AND WIND CHILL ARE COMBINED INTO THE WARNING AND MENTIONED IN BODY. WIND CHILLS ACTUALLY ARE EXPECTED TO BE A BIT MORE MODERATE IN THIS AREA DUE TO WARMER LAKE PLUME AND CLOUDS. HOWEVER WIND SPEEDS COULD BE GREATER NEAR THE LAKE. && .AVIATION... GENERALLY MVFR CONDS XPCD WITHIN POST FNTL ARCTIC WEDGE TDA AND TONIGHT. STG GRADIENT FLW WILL CONT BTWN DEPARTING SFC LOW PRES OVR CNTRL LWR MI AND INCOMING ARCTIC RIDGE W/GUSTS EASILY TO 35KTS IF NOT MORE ESP LT MORNING INTO THIS AFTN IF WE CAN MANAGE SOME INSOLATION. OTHERWISE FLW MODEL FCST FLW TRAJECTORIES KEEP BRUNT OF LK EFFECT SHSN BOTTLED UP ACRS LWR MI W/SCT SHSN XPCD FURTHER S AS COLD POOL ALOFT SWINGS THROUGH THE AREA THIS AFTN. && .SHORT TERM... TODAY THROUGH MONDAY NIGHT. ..BITTER WIND CHILLS...LAKE EFFECT SNOWSHOWERS AND INCREASING THREAT FOR POWER OUTAGES CONTINUE TO LOOM... ARCTIC COLD FRONT MAKING GOOD PROGRESS WITH TEMPS PLUMMETING BEHIND IT. MOST LOCATIONS GOING FROM MIDDLE 20S TO THE SINGLE DIGITS WITHIN 3 HOURS. ALSO BURST OF STRONGER WIND GUSTS ASSOCIATED WITH THE STG CAA WITH GUSTS IN THE 30 TO 35 KT RANGE. HAS BEEN SOME DISCUSSION ON WIND ADVISORIES FROM SURROUNDING OFFICES...BUT THINK FOR NOW WILL HOLD OFF ON ANYTHING. IF WE CAN GET SOME SUN THIS AFTERNOON AND ALLOW FOR SOME MIXING...COULD BE LOOKING AT THE NEED FOR ONE FOR THE AFTERNOON AND EVE HOURS. WILL DEFER TO DAY SHIFT TO MONITOR. HAVE LOWERED HIGHS TODAY TO BETTER REFLECT THE PUSH OF COLD AIR. STARTING AT 12Z ANTICIPATING TEMPS TO BE WELL INTO THE SINGLE DIGITS WEST TO MID TEENS EAST AS FRONT WILL JUST BE CLEARING THESE AREAS. THEN TEMPS WILL CONTINUE TO SLOWLY FALL. POPULATED WITH RUC40 DATA WHICH SEEMS TO HAVE A GOOD HANDLE ON TRENDS...WHICH WOULD PUT SOME LOCATIONS IN THE SW AREAS NEAR OR EVEN BELOW ZERO BY LATE MORNING. GIVEN UPSTREAM TEMPS ALREADY 1 ABOVE AT ORD AND CORE OF COLDEST 850 MB TEMPS POISED TO PASS OVER THE SW HALF THIS AFTERNOON WITH VALUES IN THE -25 TO -28 C RANGE /15 TO 20 DEGREES BELOW MEANS FOR DECEMBER/...THINK THIS IS REASONABLE AND GRIDS REFLECT THIS. THIS BRINGS ANOTHER CHALLENGE. IF WINDS DO REMAIN UP...THEN THESE SAME AREAS WILL APPROACH OR EXCEED WIND CHILL WARNING CRITERIA. FOR NOW WILL STICK WITH ADVISORY...BUT SPEED UP ONSET TO START WITH PACKAGE RELEASE AND LET DAY SHIFT MONITOR WINDS AND TEMPS FOR POSSIBLE UPGRADE. ALSO HAS HAS BEEN NOTED IN MANY PRODUCTS...ANTICIPATING INCREASED ISSUES WITH POWER OUTAGES AND TREE/POWER LINE DAMAGE AS STRONG WINDS OVERLOAD ALREADY BURDENED LINES AND TREES. POWER HAS ALREADY BEEN FLUCTUATING HERE AT THE OFFICE AND EXPECT THIS TO CONTINUE FOR MANY AREAS WITH ICE STILL AROUND. LAKE EFFECT SNOWSHOWERS WILL QUICKLY KICK IN BEHIND THE FRONT WITH THE BULK OF THE ACTIVITY ACROSS THE FAR NORTHERN PARTS OF THE AREA. WILL CONTINUE WITH WINTER STORM WARNING FOR BERRIEN THROUGH ST JOE COUNTIES IN MICHIGAN. WHILE BEING A BIT OF A PROLONGED EVENT...WIND CHILLS...WINDS...TEMPS AND SNOWFALL WILL ALL LEAD TO ROUGH TRAVEL IN THESE AREAS. BAND STILL LOOKS TO SET UP RATHER NICELY TOWARDS MONDAY MORNING ACROSS THE FAR SOUTHER MICHIGAN COUNTIES AND SINCE THIS HAS BEEN THERE FOR SEVERAL RUNS WILL BLEND WITH GRR AND DTX AND EXPAND LIKELY POPS OUT INTO HILLSDALE CO. WILL KEEP AMOUNTS IN THE 1 TO 2 INCH RANGE IN THESE AREAS FOR NOW. THINGS LOOK TO EASE UP FOR MONDAY AND MONDAY NIGHT TO GIVE A DRY BUT COLD FORECAST BEFORE THE NEXT SYSTEM ARRIVES IN THE LONG TERM. && .LONG TERM... DIFFICULT FCST PD THROUGHOUT. VRY INTENSE SW TROUGH OVR THE GULF OF AK YDA HAS STEAMED SEWD TO NR COASTAL WA STATE THIS MORNING...BRINGING RARE HEAVY SNOW TO KSEA AND A GOOD INDICATOR OF HOW INTENSE THIS SYS IS. UPSTREAM JET STREAK PER VAPOR LOOKS QUITE INTENSE AS WELL AND WILL AID SYS DIG INTO SWRN ROCKIES TUE. DOWNSTREAM CONDS REMAIN A MESS THOUGH W/INCOMING INTENSE ARCTIC WEDGE AND EVENTUALLY STG LL MSTR RTN OVERTOP RETREATING COLD DOME MID WEEK. 00Z GUIDANCE TAKEN AS A WHOLE TRENDING QUICKER W/PCPN DVLPMNT AND NOW INDICATING SNOW TUE AM AND SEE NO REASON TO ARGUE GIVEN UPR JET SHIFTING THROUGH THE NRN LAKES BY TUE AFTN. PRIMARY DIFFICULTY LIES W/LL THERMAL RESPONSE INTO RETREATING ARCTIC WEDGE. AS NOTED YDA...STILL FEEL MODELS ERODING ARCTIC DOME TOO QUICKLY ESP OVR DEEPER HIGH DENSITY SNOWPACK ACRS NRN PORTION OF CWA YET ON THE OTHER HAND CAN`T DISCOUNT LACK OF SNOW CVR ACRS DOWNSTATE IL/IN. THUS IT SEEMS AT LEAST THE THREAT FOR ANOTHER POTENTIALLY SIG ICING EVENT PSBL TUE NIGHT AND WED ACRS NRN/NW THIRD OF CWA. PRIOR TO THAT...MAINLY SNOW TUE INTO TUE EVENING BFR WARM LYR LEADS TO IP MIX GENERALLY SOUTH OF US 30 AND ZR SOUTH OF US 24. EJECTION OF INTENSE WRN SW LT TUE MORE DISCONCERTING GIVEN DRAMATIC MED RANGE TRENDS W/DEGREE OF SFC DVLPMNT SEEN IN 00Z GFS AND ITS ENSEMBLES. OP GFS/ECMWF SOLUTIONS SIMILAR...BOTH IN INTENSITY AND QUICKER NEWD EJECTION COMPARED W/GFS ENSEMBLES YET CERTAINLY WITHIN THE SCOPE OF POSSIBILITIES. PRIOR FLAT OPEN WV EJECTION SEEN IN 12Z RUNS COMPARABLE W/LATEST WRF 4KM RUN SO UNCERTAINTY IS HIGH. BEST RECOURSE AT THIS POINT IS TO WEIGHT WED PD MORE HEAVILY TWD A MIXED PCPN EVENT XPC PERHAPS FAR NW PER IMPLIED SFC LOW TRACK BUT DO XPC ADDNL SIG FLUCTUATIONS THROUGH THE NXT 36HRS UNTIL THIS SYS GETS FURTHER INTO UPR AIR NETWORK AND SAMPLED BTR. IN THE LEAST...ANOTHER HEAVY PRECIPITATION EVENT LIKELY TO BE REALIZED TUE NIGHT/WED. AFT THAT...PATTN RELOADS AMAZINGLY FAST W/YET ANOTHER INTENSE MID LAT CYCLONE FOR LT WEEK. ADDNL HEADACHES CERTAIN YET WILL SPARE ANY DETAILS FOR THE MOMENT GIVEN THAT TIME RANGE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL WARNING UNTIL 1 PM EST /12 PM CST/ MONDAY FOR INZ003>009-012>018-020-022>027-032>034. WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR INZ013-015-017- 018-020-022>027-032>034. WINTER WEATHER ADVISORY UNTIL 10 AM EST /9 AM CST/ MONDAY FOR INZ003>009-012-014-016. MI...WIND CHILL WARNING UNTIL 1 PM EST MONDAY FOR MIZ080-081. WINTER WEATHER ADVISORY UNTIL 10 AM EST MONDAY FOR MIZ080-081. WINTER STORM WARNING UNTIL 10 AM EST MONDAY FOR MIZ077>079. OH...WIND CHILL WARNING UNTIL 1 PM EST MONDAY FOR OHZ001-002-004-005- 015-016-024-025. WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR OHZ015-016-024- 025. WINTER WEATHER ADVISORY UNTIL 10 AM EST MONDAY FOR OHZ001-002- 004-005. LM...HEAVY FREEZING SPRAY WARNING UNTIL 5 AM EST MONDAY FOR LMZ043- 046. GALE WARNING UNTIL 5 AM EST MONDAY FOR LMZ043-046. && $$ SHORT TERM...FISHER LONG TERM...HOLSTEN AVIATION...FISHER UPDATE...LASHLEY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 653 AM EST SUN DEC 21 2008 .AVIATION... GENERALLY MVFR CONDS XPCD WITHIN POST FNTL ARCTIC WEDGE TDA AND TONIGHT. STG GRADIENT FLW WILL CONT BTWN DEPARTING SFC LOW PRES OVR CNTRL LWR MI AND INCOMING ARCTIC RIDGE W/GUSTS EASILY TO 35KTS IF NOT MORE ESP LT MORNING INTO THIS AFTN IF WE CAN MANAGE SOME INSOLATION. OTHERWISE FLW MODEL FCST FLW TRAJECTORIES KEEP BRUNT OF LK EFFECT SHSN BOTTLED UP ACRS LWR MI W/SCT SHSN XPCD FURTHER S AS COLD POOL ALOFT SWINGS THROUGH THE AREA THIS AFTN. && .SHORT TERM... TODAY THROUGH MONDAY NIGHT. ...BITTER WIND CHILLS...LAKE EFFECT SNOWSHOWERS AND INCREASING THREAT FOR POWER OUTAGES CONTINUE TO LOOM... ARCTIC COLD FRONT MAKING GOOD PROGRESS WITH TEMPS PLUMMETING BEHIND IT. MOST LOCATIONS GOING FROM MIDDLE 20S TO THE SINGLE DIGITS WITHIN 3 HOURS. ALSO BURST OF STRONGER WIND GUSTS ASSOCIATED WITH THE STG CAA WITH GUSTS IN THE 30 TO 35 KT RANGE. HAS BEEN SOME DISCUSSION ON WIND ADVISORIES FROM SURROUNDING OFFICES...BUT THINK FOR NOW WILL HOLD OFF ON ANYTHING. IF WE CAN GET SOME SUN THIS AFTERNOON AND ALLOW FOR SOME MIXING...COULD BE LOOKING AT THE NEED FOR ONE FOR THE AFTERNOON AND EVE HOURS. WILL DEFER TO DAY SHIFT TO MONITOR. HAVE LOWERED HIGHS TODAY TO BETTER REFLECT THE PUSH OF COLD AIR. STARTING AT 12Z ANTICIPATING TEMPS TO BE WELL INTO THE SINGLE DIGITS WEST TO MID TEENS EAST AS FRONT WILL JUST BE CLEARING THESE AREAS. THEN TEMPS WILL CONTINUE TO SLOWLY FALL. POPULATED WITH RUC40 DATA WHICH SEEMS TO HAVE A GOOD HANDLE ON TRENDS...WHICH WOULD PUT SOME LOCATIONS IN THE SW AREAS NEAR OR EVEN BELOW ZERO BY LATE MORNING. GIVEN UPSTREAM TEMPS ALREADY 1 ABOVE AT ORD AND CORE OF COLDEST 850 MB TEMPS POISED TO PASS OVER THE SW HALF THIS AFTERNOON WITH VALUES IN THE -25 TO -28 C RANGE /15 TO 20 DEGREES BELOW MEANS FOR DECEMBER/...THINK THIS IS REASONABLE AND GRIDS REFLECT THIS. THIS BRINGS ANOTHER CHALLENGE. IF WINDS DO REMAIN UP...THEN THESE SAME AREAS WILL APPROACH OR EXCEED WIND CHILL WARNING CRITERIA. FOR NOW WILL STICK WITH ADVISORY...BUT SPEED UP ONSET TO START WITH PACKAGE RELEASE AND LET DAY SHIFT MONITOR WINDS AND TEMPS FOR POSSIBLE UPGRADE. ALSO HAS HAS BEEN NOTED IN MANY PRODUCTS...ANTICIPATING INCREASED ISSUES WITH POWER OUTAGES AND TREE/POWER LINE DAMAGE AS STRONG WINDS OVERLOAD ALREADY BURDENED LINES AND TREES. POWER HAS ALREADY BEEN FLUCTUATING HERE AT THE OFFICE AND EXPECT THIS TO CONTINUE FOR MANY AREAS WITH ICE STILL AROUND. LAKE EFFECT SNOWSHOWERS WILL QUICKLY KICK IN BEHIND THE FRONT WITH THE BULK OF THE ACTIVITY ACROSS THE FAR NORTHERN PARTS OF THE AREA. WILL CONTINUE WITH WINTER STORM WARNING FOR BERRIEN THROUGH ST JOE COUNTIES IN MICHIGAN. WHILE BEING A BIT OF A PROLONGED EVENT...WIND CHILLS...WINDS...TEMPS AND SNOWFALL WILL ALL LEAD TO ROUGH TRAVEL IN THESE AREAS. BAND STILL LOOKS TO SET UP RATHER NICELY TOWARDS MONDAY MORNING ACROSS THE FAR SOUTHER MICHIGAN COUNTIES AND SINCE THIS HAS BEEN THERE FOR SEVERAL RUNS WILL BLEND WITH GRR AND DTX AND EXPAND LIKELY POPS OUT INTO HILLSDALE CO. WILL KEEP AMOUNTS IN THE 1 TO 2 INCH RANGE IN THESE AREAS FOR NOW. THINGS LOOK TO EASE UP FOR MONDAY AND MONDAY NIGHT TO GIVE A DRY BUT COLD FORECAST BEFORE THE NEXT SYSTEM ARRIVES IN THE LONG TERM. && .LONG TERM... DIFFICULT FCST PD THROUGHOUT. VRY INTENSE SW TROUGH OVR THE GULF OF AK YDA HAS STEAMED SEWD TO NR COASTAL WA STATE THIS MORNING...BRINGING RARE HEAVY SNOW TO KSEA AND A GOOD INDICATOR OF HOW INTENSE THIS SYS IS. UPSTREAM JET STREAK PER VAPOR LOOKS QUITE INTENSE AS WELL AND WILL AID SYS DIG INTO SWRN ROCKIES TUE. DOWNSTREAM CONDS REMAIN A MESS THOUGH W/INCOMING INTENSE ARCTIC WEDGE AND EVENTUALLY STG LL MSTR RTN OVERTOP RETREATING COLD DOME MID WEEK. 00Z GUIDANCE TAKEN AS A WHOLE TRENDING QUICKER W/PCPN DVLPMNT AND NOW INDICATING SNOW TUE AM AND SEE NO REASON TO ARGUE GIVEN UPR JET SHIFTING THROUGH THE NRN LAKES BY TUE AFTN. PRIMARY DIFFICULTY LIES W/LL THERMAL RESPONSE INTO RETREATING ARCTIC WEDGE. AS NOTED YDA...STILL FEEL MODELS ERODING ARCTIC DOME TOO QUICKLY ESP OVR DEEPER HIGH DENSITY SNOWPACK ACRS NRN PORTION OF CWA YET ON THE OTHER HAND CAN`T DISCOUNT LACK OF SNOW CVR ACRS DOWNSTATE IL/IN. THUS IT SEEMS AT LEAST THE THREAT FOR ANOTHER POTENTIALLY SIG ICING EVENT PSBL TUE NIGHT AND WED ACRS NRN/NW THIRD OF CWA. PRIOR TO THAT...MAINLY SNOW TUE INTO TUE EVENING BFR WARM LYR LEADS TO IP MIX GENERALLY SOUTH OF US 30 AND ZR SOUTH OF US 24. EJECTION OF INTENSE WRN SW LT TUE MORE DISCONCERTING GIVEN DRAMATIC MED RANGE TRENDS W/DEGREE OF SFC DVLPMNT SEEN IN 00Z GFS AND ITS ENSEMBLES. OP GFS/ECMWF SOLUTIONS SIMILAR...BOTH IN INTENSITY AND QUICKER NEWD EJECTION COMPARED W/GFS ENSEMBLES YET CERTAINLY WITHIN THE SCOPE OF POSSIBILITIES. PRIOR FLAT OPEN WV EJECTION SEEN IN 12Z RUNS COMPARABLE W/LATEST WRF 4KM RUN SO UNCERTAINTY IS HIGH. BEST RECOURSE AT THIS POINT IS TO WEIGHT WED PD MORE HEAVILY TWD A MIXED PCPN EVENT XPC PERHAPS FAR NW PER IMPLIED SFC LOW TRACK BUT DO XPC ADDNL SIG FLUCTUATIONS THROUGH THE NXT 36HRS UNTIL THIS SYS GETS FURTHER INTO UPR AIR NETWORK AND SAMPLED BTR. IN THE LEAST...ANOTHER HEAVY PRECIPITATION EVENT LIKELY TO BE REALIZED TUE NIGHT/WED. AFT THAT...PATTN RELOADS AMAZINGLY FAST W/YET ANOTHER INTENSE MID LAT CYCLONE FOR LT WEEK. ADDNL HEADACHES CERTAIN YET WILL SPARE ANY DETAILS FOR THE MOMENT GIVEN THAT TIME RANGE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ MONDAY FOR INZ003>009-012>018-020-022>027-032>034. MI...WIND CHILL ADVISORY UNTIL 1 PM EST MONDAY FOR MIZ080-081. WINTER STORM WARNING UNTIL 10 AM EST MONDAY FOR MIZ077>079. OH...WIND CHILL ADVISORY UNTIL 1 PM EST MONDAY FOR OHZ001-002-004-005- 015-016-024-025. LM...HEAVY FREEZING SPRAY WARNING UNTIL 5 AM EST MONDAY FOR LMZ043- 046. GALE WARNING UNTIL 5 AM EST MONDAY FOR LMZ043-046. && $$ SHORT TERM...FISHER LONG TERM...HOLSTEN AVIATION...HOLSTEN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 620 AM EST SUN DEC 21 2008 .AVIATION... DISCUSSION FOR 12Z TAFS. ARCTIC FRONT HAS CROSSED THE AREA AND BITTERLY COLD WEATHER ALONG WITH STRONG GUSTY WINDS ARE EXPECTED TODAY. WINDS WILL REMAIN IN THE SUSTAINED RANGE OF 20 TO 25KTS THROUGH 00Z WITH GUSTS AS HIGH AS 36KTS DURING THIS TIME. SKIES WILL BEGIN THE PERIOD CLEAR...BUT AS VERY COLD AIR ALOFT MOVES IN...A BKN CU FIELD IS EXPECTED TO DEVELOP ACROSS THE AREA AFTER 15Z. INDICATIONS ARE THAT THIS CLOUD DECK WILL BE RIGHT AROUND 3KFT EVERYWHERE EXCEPT LAF WHERE IT SHOULD BE AROUND 2500 FEET AND THUS IN THE MVFR RANGE. CLOUDS WILL DISSIPATE AROUND 01Z AND THEN SLOWLY CLEAR OVERNIGHT TO SCATTERED CLOUDS BY 12Z. AS FOR WINDS...THE GUSTINESS WILL DISSIPATE BY 06Z AND THEN SUSTAINED WINDS WILL DROP OFF INTO THE 10-15KT RANGE BY 12Z. && .PREV DISCUSSION... /ISSUED 300 AM EST SUN DEC 21 2008/ DISCUSSION... MAIN PROBLEM FOR THE SHORT TERM WILL BE THE WINDS AND TEMPERATURES. VERY STRONG LOW PRESSURE OVER SOUTHERN OHIO MOVING EAST. EXTREMELY TIGHT PRESSURE AND TEMPERATURE GRADIENT MOVING INTO INDIANA. AT INDY HAD A WIND GUST TO 43 MPH AT 130 AM. RUC HAS 48 MPH WINDS AT 2,500 FT THIS AFTERNOON. WITH A GOOD AMOUNT OF SUNSHINE ESPECIALLY DURING THE MORNING THERE WILL BE GOOD MIXING. THIS WILL KEEP WINDS ABOVE ADVISORY LEVELS CENTRAL AND N AND CLOSE ENOUGH IN THE SOUTH. THE WINDS WILL DROP DOWN AFTER SUNSET. ALL OF THE MODELS ARE WAY TO WARM WITH THE TEMPS. THE NAM WHICH IS THE COLDEST AT HUF AT 09Z HAS 20 THEY WILL BE 16 OR MAYBE LOWER. THE NAM 850 MB TEMPS DROP TO -25 THIS AFTERNOON. SO HAVE CUT GUIDANCE HIGHS WAY BACK TODAY. THEY MAY TRY TO REBOUND SOME THIS AFTERNOON BUT WITH COLD AIR SC MOVING IN THIS WILL SLOW THAT ALONG WITH THE SHORTEST PERIOD OF SUNSHINE OF THE YEAR. THIS WILL PUT WIND CHILL VALUES WELL INTO ADVSRY LEVELS. EVEN THOUGH WINDS WILL DECREASE THIS EVENING THEY WILL REMAIN HIGH ENOUGH WITH THE TEMPS JUST ABOVE ZERO TO KEEP THE ADVSRY GOING THROUGH 12Z MONDAY. THE WEDGE OF EXTREMELY COLD AIR WILL MOVE EAST OF INDIANA ON MONDAY. THIS ALONG WITH AT LEAST PARTLY SUNNY WILL ALLOW TEMPS TO REBOUND BUT HIGHS WILL STILL REMAIN IN THE TEENS. MODEL TIME SECS FAVOR SOME CLRG ON MON AS LOW LVL MOISTURE THINS AND SFC HIGH PRES SETTLES ACRS THE OH VLY ALONG WITH A FLAT UPR RIDGE. NICE RETURN FLOW ON TUESDAY AHEAD OF AN APRCHG CD FNT SHOULD BRING SOME LGT SN IN TUES PM AND CHRISTMAS EVE PERHAPS MIXED WITH RN S PER SOUNDINGS AND CRITICAL THICKNESS PROGS. MODELS SUGGESTING MORE PRECIP IN THE EXTENDED THAN EITHER HPC OR THIS MRNGS FCST. GFS AND ECMWF HAVE A LOT OF DIFFERENCES BUT ARE TRENDING TOWARD A PROLONGED PD OF RETURN FLOW AHEAD OF A SLOW MOVING CD FNT. SO...OVERRUNNING SECENARIO PSBL WITH RN/SN MIX SUGGESTED BY THICKNESSES. LEANED A LITTLE MORE TOWARDS THE USUALLY MORE ACCURATE ECMWF AND HAVE PRECIP IN ON CHRISTMAS NGT && .IND WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ021-028>031- 035>049-051>057-060>065-067>072. WIND CHILL ADVISORY UNTIL 7 AM EST MONDAY FOR INZ021-028>031- 035>049-051>057-060>065-067>072. && $$ AVIATION...JOHNSON in AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 711 AM EST SUN DEC 21 2008 .SYNOPSIS... LOW PRESSURE JUST EAST OF THE DELMARVA PENINSULA THIS MORNING WILL DEEPEN AS IT MOVES TOWARD CAPE COD LATER TODAY. GUSTY NORTHWEST WINDS WILL DEVELOP ACROSS THE REGION EARLY THIS AFTERNOON...AND BRING VERY COLD AIR ACROSS THE MID ATLANTIC TONIGHT THROUGH MONDAY NIGHT. HIGH PRESSURE WILL BUILD INTO THE REGION ON TUESDAY... MODERATING TEMPATURES TO ABOVE SEASONABLE NORMS BUT WITH BETTER THAN NORMAL CHC FOR CLOUDS AND PCPN FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 08Z SFC ANALY FEATURES FRACTURED LOPRES FM WRN PA SWD TO WRN VA-- CNTRS NR PIT AND GEV. A HIPRES RDG EXTEND SWD FM NEW ENGLND DWN I-95 CRRDR TO DC. PLENTY OF LLVL COLD AIR IN PLACE...W/ FRZG LN JUST ABT TO EZF-CGE. AT 11Z...LOWS HV SPLIT FURTHER. THE NRN LOW HAS RETROGRADED BACK TWD GRTLKS...CLSR TO H5 CYCLONE. SRN LOW IN WRN NC. BUT...PRIND CSTL RDVLPMNT TAKING PLACE OFF ACY. RGNL RADAR MOSAIC DEPICTS MOST OF THE MSTR NOW E OF BLURDG. SWATH OF FAIRLY INTENSE REFLECTIVITIES OMH-ESN. RECVD REPORT OF SOME WET SNW IN SRN CHARLES CNTY A CPL HRS AGO. SEEMS AS THO COLD AIR BEING DRAGGED DOWN. GDNC HAS BEEN STRUGGLING A BIT IN CAPTURING EXTENT OF THE SUBFRZG AMS. LWX-WRF-ARW4N SEEMS TO BE DOING RELATIVELY WELL. OF THE SYNOPTIC SCALE MDLS...NAM12 PREFERRED. IT/S BEEN MAINLY FZDZ ACRS CWFA THUS FAR...THO 88D SUGGESTS A FEW POCKETS OF PL OUT THERE. SPOTTER CALLS/EMAILS INDICATE ACCRETION HAS BEGUN. PLS KEEP THOSE CALLS COMING! THE SRN LOW WL TRANSLATE ACRS SSIDE VA ELY THIS MRNG. H5 SUPPORT LINGERS BACK ACRS GRTLKS. JETSTREAM ACRS CWFA...BUT 160KT JETMAX BACK ACRS OHVLY. QPF WL CONT TO BE ON THE LGT SIDE TIL SFC AND UPR LVL FEATURES PHASE AND TAKE ON A NEG TILT. STORM WL BE PAST CWFA BY THE TIME THAT HPPNS. WE/VE JUST ABT REACHED OUR WINDOW OF OPPORTUNITY. DYNAMICS SUFFICIENT TO SUPPORT CONTD PCPN THRU ABT 15Z. AS JUST MNTND...SFC LOW WL BE OFF DELMARVA BY THEN...AND WNDS WL TURN WLY RATHER SHARPLY. SIGNIFICANTLY LWR DEWPTS WL ADVECT EWD AT THAT PT...WHICH SHUD MARK NOT JUST END OF PCPN...BUT ALSO PRTL CLRG FOR THE AFTN HRS. IN TERMS OF PTPYE...GOING MAINLY W/ FZRA/FZDZ. NOT ONLY DO OBS SUPPORT IT...BUT MDL SNDGS DEPICT STRONG H8 WAA...LEADING TO A NOTABLE WM AIR INTRUSION WHILE SFC LYR SHALLOW. AT STORMS END...ENUF COLD AIR LIKELY TO ADVECT INTO MTNS FOR IT TO POTENTIALLY END AS SN. SINCE FRZG LN HAS SUNK FAIRLY FAR S INTO VA...AM SUSPECT ABT PCPN ENDING AS RA XCPT FOR EZF-NHK. BUT...ESELY SFC FLOW ATTM SUGGESTS IT STILL PSBL ABT DCA-BWI. WL HEDGE BETS THAT WAY...WHICH STILL IS COLDER THAN SYNOPTIC SCALE GDNC. /BTW...WRF-ARW4 SUPPORTS A WARMER END ALL THE WAY W INTO SHEN VLY. WE SHALL SEE./ --CHGS FOR THIS UPDT-- WL ALLW ADDED SEGMENT TO WSW ACRS SERN CWFA /SRN MD AND INVOF EZF/ TO EXPIRE AT 12Z. TEMPS STILL BRDRLN 32F. BUT...RAFL RATES HIER THAN ANTICIPATED...MORE IN LN TO WHAT RUC SUGGESTED. ICE ACCRETION WONT TAKE PLACE W/ THAT MUCH LIQUID AND ONLY BDRDLN TEMPS. ELSW...WL LV ADVYS STAND AS IS. ALTHO STDY PCPN LIKELY WL BE ENDING PRIOR TO EXPIRATION TIME...PATCHY FZDZ LIKELY TO LINGER. PERFER TO HOLD ONTO ADVY TIL SOME SIGN OF TEMP RISE BEGINS...WHICH WL BE AFTR SUNRISE. PLUS...XPCT SHIELD OF PCPN TO PIVOT BACK AS CSTL STORM STRENGTHENS/ATTAINS NEG TILT. SO...AREA THAT HAD ADVY EXTENDED TIL NOON STILL WONT BE OUT OF THE WOODS SOON. INSTEAD OF FZRA...IT/LL BE COLD TEMPS AND FZDZ...KEEPING ICY CONDS IN PLACE. SFC LOW CONSOLIDATES AND STRENGTHENS TAFTN. INCRSD P-GRAD WL LEAD TO WINDY CONDS...BUT MOMENTUM TRANSFER SUGGESTS IT WL BE JUST THAT-- WINDY BUT ADVYS NOT REQD. DAY CREW WL NEED TO MONITOR AND INTERROGATE LATER GDNC TO SEE IF ADJUSTMENTS REQD. ONCE SYSTEM DEPARTS...UPSLOPE COMPONENT REPONSIBLE FOR SCT SHSN. BUT...FLOW SO STRONG AND TRAJ WLY THAT IT WONT BE ABLE TO ORGANIZE OR PICK UP NEEDED MSTR. THUS...POPS NO HIER THAN CHC. GIVEN STRONG CAA...MAXT WL BE A STRUGGLE BTWN PROCESSES. THINK THE DWNSLOPE AND CLRG WL ALLW A QUICK BURST BEFORE CAA REALLY KICKS IN. THAT PERMITS RISING TEMPS...BUT NOT AS MUCH AS GDNC SUGGESTS. THUS...FCST MAXT WL BE UNDER GDNC VALUES. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... SUNDAY NIGHT THE TRAILING H5 VORT MAX WILL MOVE THROUGH THE CWA...WITH A REINFORCING SHOT OF LLVL CAA AS H85 TEMPS DROP TO -20C. THIS CAA WILL PRODUCE A DRY ADIABATIC LAPSE RATE TONIGHT UP TO H75...WHERE WINDS ARE 40+KTS. SHOULD SEE A GUSTY WIND PARTICULARLY BETWEEN SUNSET AND 2 AM...WILL KEEP IT JUST BLO WIND ADVSRY FOR NOW. MOST LIKELY WILL SEE WIND CHILL ADVSRY THRESHOLDS IN THE HIER ELEVATIONS ABV 1500 FT LATE TONIGHT/MON MORNING...BUT THAT IS LATE 2ND/ERLY 3RD PD SO WILL NOT ISSUE ANY WIND CHILL ADVSRY ATTM BUT HIGH LIKELIHOOD OF OCCURENCE. MONDAY WILL BE NW FLO DAY WITH SCT-BKN SC BUT GUSTY WIND WILL DIMINISH THROUGH THE DAY. UPSLOPE MACHINE WILL BE ON IN WESTERN 5 TONIGHT THROUGH MONDAY BUT A BIT STARVED OF MOISTURE SO ONLY INCH OR SO XPCTD ATTM. MONDAY NIGHT THE SFC HIGH FROM THE TN VALLEY BUILDS IN AND STARTS PUMPING WARM AIR INTO REGION. TUE NIGHT MIGHT SEE OVERUNNING PCPN START AS A BRIEF PD OF FZRA BUT WITH STRONG WAA AND SOUTHERLY WINDS WILL QUICKLY CHANGEOVER TO RAIN. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... MODERATING TEMPS MID WEEK THROUGH THE REMAINDER OF THE PERIOD...WITH LONG RANGE MEX GDNCE GIVING HIGHS LATE IN THE WEEK U50S/L60S. BUT NOT WITHOUT ALOT OF CLOUDS AND POTL FOR WARM FRONTAL SHRA XMAS NIGHT AND FRI. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... SHIELD OF PCPN E OF BLURDG. TEMPS ACRS TERMINALS BLO FRZG...SO PTYPE FZRA/FZDZ. STDY PCPN WL END SHORTLY...BUT PATCHY FZDZ WL LINGER THRU MRNG...AS TEMPS WON/T RISE ABV 32F ALL THAT QUICKLY. ELY WNDS WL BECOME WLY BY MIDDAY...WHICH WL SCOUR OUT ANY FLGT RESTRICTIONS. AS P-GRAD INCREASES...XPCT WNDS TO PICK UP TO 15-30 KT DURING AFTN...CONTG INTO EVNG. SUN NGT AND MON..STRONG NW WINDS WL GENERATE MECHANICAL TURBULENCE IN LEE OF THE APLCHNS. OTRW...VFR XPCTD THRU AT LEAST TUE. NXT THREAT OF FLGT RESTRICTIONS COMES TUE NGT-WED. && .MARINE... LOPRES TRACKS ACRS WATERS THIS MRNG. PGARD INCR IN ITS WAKE. GLW ALREADY IN PLACE TAFTN. MOMENTUM TRANSFER SUGGESTS 35 KT GUSTS W/IN REACH. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR DCZ001. MD...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR MDZ501-502. WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR MDZ003>007- 009>011-013-014. VA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ021-025>027-029-030-036>041-050-051. WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR VAZ028-031- 042-052>054. WV...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR WVZ050-054-055-501>504. WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR WVZ051>053. MARINE...GALE WARNING FROM 1 PM THIS AFTERNOON TO 6 PM EST MONDAY FOR ANZ530>537. && $$ SYNOPSIS...LEE NEAR TERM...HTS SHORT TERM...LEE LONG TERM...LEE AVIATION...HTS MARINE...HTS/LEE md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 357 PM EST SUN DEC 21 2008 .SHORT TERM... ...DANGEROUS AND POTENTIALLY DEADLY WINTER CONDITIONS CONTINUE... AFTER COLLABORATION WITH KGRR AND THEIR DISCUSSIONS WITH MICHIGAN STATE POLICE...HAVE DECIDED TO UPGRADE BERRIEN AND CASS COUNTIES TO A BLIZZARD WARNING. CONDITIONS BEING MET ALONG MAJOR ROADS WITH HIGHWAYS AND INTERSTATES BEING CLOSED DUE TO ZERO VISIBILITIES AND HIGH WINDS. KBEH OBSERVATION CERTAINLY CLOSE OR MEETING CRITERIA AT TIMES SO HAVE ADJUSTED HEADLINES TO MATCH KGRR. ARCTIC COLD AIR NOW IN PLACE OVER OUR AREA WITH MOST LOCATIONS AROUND ZERO THIS AFTERNOON. COLD AIR STRATOCU FINALLY DEVELOPING DESPITE SUBSIDENCE AND VERY DRY AIRMASS. LAKE EFFECT SNOW SHOWERS HAVE BEEN ONGOING IN BERRIEN BUT AS EXPECTED HAVE BEEN ON LIGHT SIDE. STRONG GRADIENT FLOW AND DIURNAL MIXING WITH SUN HAS LED TO WINDS NEAR OR ABOVE ADVISORY LEVEL WITH NUMEROUS POWER OUTAGES AND RECENT REPORT OF I94 ACCIDENT AND ROAD CLOSURE IN NEAR WHITEOUT CONDITIONS. WILL CONTINUE HEADLINES. BULK OF COLD AIR TO PASS OVER THE AREA THIS EVENING WITH 850MB TEMPS PROGGED TO BE NEAR A STAGGERING NEGATIVE 28C. RATHER UNUSUAL SETUP AS THIS COLD CORE PASSES OVER AREA THIS EVENING AND TEMPS BEGIN TO WARM WITH PASSAGE OF A SHORT WAVE TROUGH ON BACKSIDE OF MAIN UPPER LOW TO THE NORTH AND INCREASING CLOUD COVER. NAM 2M SURFACE TEMPS AND MANY OF THE WRF RUNS NOT HANDLING SURFACE TEMPS WELL AT ALL AND TOO WARM THIS AFTERNOON. RUC DOING BEST JOB AND GENERALLY FOLLOWED WITH BLEND OF CURRENT COLD GRIDS THROUGH END OF RUC CYCLE. PROBLEM IS POTENTIAL WARMING OVERNIGHT WITH CLOUD COVER AND LAKE PLUME INCREASING. WILL TREND TOWARD STEADYING TEMPERATURES OVERNIGHT OUTSIDE OF LAKE EFFECT PLUME AND RISING TEMPERATURES WITHIN MODIFIED PLUME OFF OF LAKE. AS FOR LAKE EFFECT SNOW EVENT...POOR DGZ REGION EARLY THIS EVENING BEGINS TO CLIMB AND BECOME LOCATED WITHIN MOIST LAYER AND MAXIMUM OMEGA OVER SOUTHERN LAKE MICHIGAN AS 925-700MB LAYER BEGINS TO WARM. DELTA T VALUES REMAIN IN LOWER 20S AND WINDS BEGIN TO DROP TO A MORE FAVORABLE SPEED WITH LONGER FETCH OVER LAKE. KSBN BUFKIT SOUNDING STILL SHOWS INVERSION HANGING ON BUT KAZO AND KGRR PROFILES MUCH MORE FAVORABLE. NAM WRF 4KM SHOWING LAKE EFFECT IMPROVING THROUGH THE NIGHT WITH INDICATIONS OF A COUPLE DOMINATE BANDS...THE SECOND BEING OVER OUR NORTHEAST FORECAST AREA INTO BRANCH AND HILLSDALE COUNTIES. THIS SECOND BAND WILL BE INTERESTING AND IF IT INDEED DEVELOPS WILL NEED TO INCREASE AMOUNTS IN THOSE AREAS FROM CURRENT RANGE. HOWEVER...FOR NOW WILL FOCUS ON BETTER CHANCE AREA OF IMPACT IN CURRENT WARNING AREA. LOW LEVEL SHEAR REMAINS HIGHER THAN PREFERRED TONIGHT SO HAVE CONTINUED WITH A GENERAL 4 TO 8 INCH SNOW RANGE BUT STILL LOCALLY HIGHER AMOUNTS POSSIBLE IF IDEAL CONDITIONS CAN SET UP AND PERSIST...MAINLY NORTHERN PARTS OF MICHIGAN COUNTIES. FLOW BEGINS TO BACK MONDAY BY MID TO LATE MORNING WITH FLOW TURNING MORE SOUTHWEST. WILL HAVE CATEGORICAL POPS EARLY MORNING AND TRANSITION TO CHANCE POPS BY AFTERNOON BEFORE LAKE EFFECT ENDS. MONDAY NIGHT TEMPERATURES WILL BE TRICKY AND COULD HELP SET STAGE FOR NEXT PCPN EVENT COMING IN FOR TUESDAY. AS WE SAW THIS PAST THURSDAY EVENING PRIOR TO ARRIVAL OF ICE STORM...SKIES CLEARED BRIEFLY IN THE EVENING WITH LIGHT WINDS AND SURFACE HIGH NEARBY. TEMPS DROPPED WELL BELOW GUIDANCE EARLY BEFORE RECOVERING DURING EVENT. SIMILAR SET UP APPEARS LIKELY MONDAY NIGHT WITH SKIES CLEARING AND WINDS LIGHT BEFORE CLOUDS INCREASE OVERNIGHT WITH WARM AIR ADVECTION. HAVE CONTINUED WITH LOWS WELL BELOW GUIDANCE OVER LOCKED SNOW PACK THAT IS FRESH IN AREAS AND FROZEN SOLID IN OTHERS. SHOULD SEE ANOTHER NIGHT NEAR ZERO SOUTHWEST AND BELOW ZERO NORTHEAST WITH TEMPS STEADY OR SLOWING RISING LATE MONDAY NIGHT. && .LONG TERM...(TUESDAY THROUGH SUNDAY)... MAIN AREA OF CONCERN IS WITH POTENTIAL FOR SIGNIFICANT STORM TUESDAY NIGHT INTO CHRISTMAS EVE AS A POTENT SYSTEM WORKS ACROSS THE REGION. MODEL CONFIDENCE IS MARGINAL IN THIS TIME FRAME AND LOW BEYOND IT AS ACTIVE PATTERN CONTINUES WITH MORE MODERATE TEMPERATURES. LEE SIDE CYCLOGENESIS MONDAY LEADS TO SFC LOW EJECTING IN SW FLOW AS WESTERN CONUS TROF FLATTENS AND EJECTS UPR LEVEL ENERGY ALONG MID LVL BAROCLINIC ZONE. SFC LOW PROGGED TO TRACK OVER INDIANA WHICH BRINGS INEVITABLE PTYPE CONCERNS. ESSENTIALLY A ONE TWO PUNCH WITH WAA PRECIP TUESDAY NIGHT FOLLOWED BY THE SFC LOW ITSELF EARLY WEDNESDAY. INITIAL TEMPS ARE COLD ENOUGH FOR ALL SNOW TO BREAK OUT IN WAA REGION AHEAD OF ADVANCING LOW. GOMEX IS WIDE OPEN BY MIDDAY TUESDAY AND THE MODEL SUITE IS IN GENERAL AGREEMENT ON SETTING THE STAGE FOR MODERATE SNOWFALL ESP ACROSS NORTHERN THIRD OF FORECAST AREA TUESDAY NIGHT. PERHAPS A BRIEF BREAK BEFORE THE SFC FEATURE ADVANCES BRINGING IN THE SECOND ACT AS WARM AIR RAPIDLY ADVANCES AHEAD OF LOW WITH 60+ KT FLOW AT H85 STREAMING WARM MOIST AIR THROUGH LOW LEVELS INTO THE CWA. AS USUAL MUCH MODEL DISAGREEMENT WITH AMOUNT OF WARMING AND EFFECTS ON THERMAL PROFILE/PTYPE. HAVE BASICALLY FOLLOWED A COMBINATION OF GFS ENSEMBLE MEAN AND A BIT OF FURTHER SOUTH..COLDER SREF AND AWAY FROM THE WARM BIASED ECMWF. ABV FZ H85 TEMPS MIGRATE INTO NORTH CWA WHILE SFC TEMPS REMAIN TANTALIZINGLY CLOSE TO THE FZ MARK. SREF PLUMES INDICATE TRANSITION TO NON-TRIVIAL FZRA AMOUNTS SOUTHERN HALF CWA WITH CHANGEOVER TO ALL RAIN POSSIBLE EXTREME SOUTH. GIVEN SPREAD IN SOLUTIONS EVEN AMONG ENSEMBLE MEANS HAVE KEPT MIXED BAG OF PRECIP IN THIS AREA FROM ONSET THROUGH RETURN TRANSITION TO ALL SNOW BEHIND SFC LOW LATE ON WED. WITH HIGH UNCERTAINLY IN PTYPE AND SUSPECT QPF AMOUNTS AFTER COLLAB WITH NEIGHBORING WFOS HAVE HELD OFF ISSUING WATCH AND WILL LET NIGHT SHIFT REASSESS OFF NEXT MODEL CYCLE FOR BETTER CONFIDENCE. NEVERTHELESS...TRAVELERS SHOULD RECOGNIZE THAT A SIGNIFICANT WINTER STORM IS POSSIBLE ACROSS THE CWA TUESDAY NIGHT INTO CHRISTMAS EVE AND SHOULD PLAN ACCORDINGLY. A BRIEF BREAK BEHIND THIS SYSTEM WITH MORE MODERATE COLD AIR BEFORE MODELS INDICATE ANOTHER IN SERIES OF SYSTEMS IMPACTING THE REGION FOR THE FOLLOWING WEEKEND. TRENDS AT THIS TIME AMONG GFS/ECMWF ARE TOWARDS A COLD RAIN EVENT BUT IT IS MUCH TOO EARLY TO BANK ON ANY PARTICULAR OUTCOME. TIMING DIFFERENCES STILL APPARENT BUT OVERALL CONSISTENCY IN BRINGING IN NEXT SYSTEM SAT/SUN REMAINS. && .AVIATION...18Z TAFS VERY DRY/COLD AIRMASS AND LARGE SCALE SUBSIDENCE BEHIND ARCTIC FRONT HAS LED TO VFR CONDITIONS AT BOTH TAF SITES. SHOULD SEE VFR CONDITIONS CONTINUE AT LEAST THROUGH THE MID AFTN HOURS...ALTHOUGH DEVELOPING CU FIELD MAY ALLOW FOR BKN HIGH END MVFR CIGS. WILL REMAIN OPTIMISTIC WITH SCT020 FOR NOW AND AMEND IF NEEDED. STRONG SFC PRESSURE GRADIENT BEHIND LOW TRACKING INTO THE EASTERN LAKES HAS ALLOWED WINDS TO GUST NEAR 35 KTS. EXPECT THESE STRONG WESTERLY WINDS TO CONTINUE INTO THIS EVENING BEFORE DIMINISHING LATE TONIGHT INTO MONDAY AS A SFC HIGH BUILDS INTO THE MID MS VALLEY. MAIN FCST ISSUE WILL BE EVOLUTION OF LAKE EFFECT SHSN ACTIVITY LATE THIS AFTERNOON INTO TONIGHT AS SECONDARY TROUGH AXIS PIVOTS THROUGH ON BACKSIDE OF DEEP UPPER VORTEX. FLOW WITHIN THE CLOUD BEARING LAYER WILL SHIFT MORE WNW WHICH WILL ALLOW SHSN ACTIVITY AND MVFR SC DECK TO IMPACT FWA/SBN. THERE IS THE POTENTIAL FOR BRIEF LIFR/IFR VIS RESTRICTIONS AT SBN LATE THIS AFTN AND TONIGHT. FOR NOW...WILL CONTINUE WITH && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL WARNING UNTIL 1 PM EST /12 PM CST/ MONDAY FOR INZ003>009-012>018-020-022>027-032>034. WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR INZ013-015-017- 018-020-022>027-032>034. WINTER WEATHER ADVISORY UNTIL 10 AM EST /9 AM CST/ MONDAY FOR INZ003>009-012-014-016. MI...WIND CHILL WARNING UNTIL 1 PM EST MONDAY FOR MIZ080-081. WINTER WEATHER ADVISORY UNTIL 10 AM EST MONDAY FOR MIZ080-081. BLIZZARD WARNING UNTIL 10 AM EST MONDAY FOR MIZ077-078. WINTER STORM WARNING UNTIL 10 AM EST MONDAY FOR MIZ079. OH...WIND CHILL WARNING UNTIL 1 PM EST MONDAY FOR OHZ001-002-004-005- 015-016-024-025. WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR OHZ015-016-024- 025. WINTER WEATHER ADVISORY UNTIL 10 AM EST MONDAY FOR OHZ001-002- 004-005. LM...HEAVY FREEZING SPRAY WARNING UNTIL 5 AM EST MONDAY FOR LMZ043- 046. GALE WARNING UNTIL 5 AM EST MONDAY FOR LMZ043-046. && $$ SHORT TERM...LASHLEY LONG TERM...LUDINGTON AVIATION...STEINWEDEL in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 239 PM EST SUN DEC 21 2008 .DISCUSSION... FORECAST FOCUS IS ON TEMPERATURES EARLY THEN ON ANOTHER POTENTIAL ICING EVENT FOR TUE. AT 19Z SFC HIGH PRESSURE WAS ACROSS THE PLAINS STATES...WHILE LOW PRESSURE WAS JUST INSIDE SERN CANADA. THE GRADIENT BETWEEN THESE WAS CREATING SFC WINDS GUSTS OVER 40 MPH ACROSS PARTS OF THE FORECAST AREA /FA/. TEMPERATURES WERE QUITE COLD AND IN THE SINGLE DIGITS TO MID TEENS. MODELS IN FAIR AGREEMENT...ALTHOUGH MOST DO NOT HAVE A HANDLE ON THE COLD AIR. FOR THE BIGGER PICTURE WILL LEAN TOWARD A BLEND OF SOLUTIONS...USING THE ECMWF/GFS ENSEMBLE MEAN FOR THE EXTENDED AND A BLEND OF THE SREF AND GFS FOR THE SHORT TERM. FOR TEMPERATURE DETAILS WILL NOT RELY ON ANY SPECIFIC MODEL. CLOUDS WILL DISSIPATE SOME OVERNIGHT WITH LOSS OF HEATING AND AS UPPER TROF AXIS MOVES OFF TO THE E. RUC IS THE ONLY MODEL THAT IS HANDLING THE CURRENT TEMPERATURES. USING IT WOULD BRING TEMPERATURES WELL BELOW ZERO ACROSS THE NRN FA. NOT QUITE SURE THAT IT WILL GET THAT COLD WITH CLOUDS EARLY AND WITH CORE OF COLD AIR MOVING OFF OVERNIGHT. HOWEVER WOULD NOT BE SURPRISED IF IT DOES COME TRUE. WILL COMPROMISE AND GO A COUPLE OF DEGREES BELOW ZERO ACROSS FAR NRN FA AND IN THE SINGLE DIGITS ABOVE ZERO ELSEWHERE. THIS IS BELOW ALL MOS. STRONG WINDS WILL DIMINISH AFTER SUNSET...BUT WITH THE COLD TEMPS WIND CHILL ADVISORY IS STILL WARRANTED. WILL BE FLIRTING WITH WIND CHILL WARNING CRITERIA ACROSS EXTREME N...BUT OVERALL ADVISORY SHOULD HOLD IT. MEANWHILE THE WIND ADVISORY WILL END AT 700 PM AND THIS LOOKS GOOD OVERALL...SO WILL LET IT RIDE. ON MONDAY EXPECT SOME SUNSHINE AND WARMER TEMPERATURES...ALTHOUGH STILL WELL BELOW NORMAL. GIVEN HOW POORLY MOS IS DOING WITH TEMPS...WENT COOLER THAN MOS FOR HIGHS. MONDAY NIGHT CLOUDS WILL INCREASE AS WARM ADVECTION BEGINS ALOFT. THIS WILL KEEP TEMPS FROM FALLING MUCH AND THEN ALLOWING THEM TO RISE SOME LATE. MODELS ARE HINTING AT SOME PRECIP IN THE NWRN FA BEFORE 12Z BUT LOWER ATMS IS QUITE DRY. ATTM FEEL THAT ANY PRECIP WOULD EVAPORATE. THUS WILL KEEP DRY FORECAST. ON TUE STRONG WARM ADVECTION ALOFT WILL GENERATE PRECIP ACROSS THE FA AS THE DAY PROGRESSES. BUFKIT SOUNDINGS...WHICH WORKED WELL WITH LAST EVENT...INDICATE PRECIP STARTING OUT AS SNOW ACROSS THE N AND AS A MIX OF SNOW AND SLEET ACROSS THE SOUTH. BY AFTERNOON ENOUGH WARM AIR WILL WORK IN ALOFT FOR PRECIP TO BE FREEZING RAIN ACROSS SRN HALF OF FA AND SNOW/SLEET MIX ACROSS NRN FA. COULD BE A FEW INCHES OF ACCUMULATING SNOW IN THE NRN FA WHERE COLDEST TEMPS WILL LINGER LONGEST. WITH COLD AIR HANGING ON AT THE SFC...THERE MAY BE SOME ICE ACCUMULATION ACROSS CENTRAL FA TUE AFTN...BUT ATTM FEEL ACCUMULATIONS WILL BE LESS THAN WARNING CRITERIA. SRN FA WILL WARM TO OR CLOSE ENOUGH TO FREEZING FOR ONLY MINOR ICE ACCUMULATIONS. TUE NIGHT FORCING INCREASES WITH AN UPPER JET MOVING IN ALONG WITH STRONG FRONTOGENESIS. THUS WILL GO CATEGORICAL POPS. MUCH OF FA WILL WARM TO AT LEAST JUST ABOVE FREEZING SO MOST OF THE NIGHT WILL BE JUST A COLD RAIN. NRN FA WILL STILL HAVE A THREAT FOR FREEZING RAIN EARLY ON UNTIL TEMPS RISE TO ABOVE FREEZING. RAIN WILL STILL BE LIKELY ON WED AHEAD OF A COLD FRONT. SAID FRONT WILL SWEEP ACROSS THE FA DURING THE DAY AND SHUT OFF THE BULK OF THE PRECIP BEFORE THE COLD AIR MOVES IN AND CHANGES LEFTOVERS TO SNOW. COULD BE ANOTHER BREEZY DAY WITH TEMPS FALLING IN THE AFTN. THANKS TO IWX AND LMK FOR COORDINATION. && .AVIATION... DISCUSSION FOR 18Z TAFS. STRONG AND BITTERLY COLD W-NW FLOW WILL CONTINUE THIS AFTERNOON. PRESSURE GRADIENT WILL GRADUALLY DIMINISH TONIGHT AND MONDAY AS HIGH PRESSURE BUILDS INTO THE MID MISSISSIPPI VALLEY LATER TONIGHT AND EVENTUALLY INTO THE LOWER OHIO VALLEY MONDAY. WINDS MAY TEMPORARILY INCREASE SOME THIS AFTERNOON AS DAYTIME MIXING LEVEL INCREASES. MIE ALREADY REPORTED A WIND GUST UP TO 39 KNOTS. MODEL SOUNDINGS ESPECIALLY NAM SHOWS BROKEN CLOUDS INCREASING THIS AFTERNOON. GFS/RUC ALSO SHOW THIS...BUT NOT QUITE AS STRONG AS NAM AND GFS IS QUICKER TO CLEAR US OUT LATER TONIGHT. WILL GO WITH LATTER SCENARIO AS CURRENTLY NOT MUCH CLOUDS UPSTREAM. THEY MAY TEMPORARILY INCRAESE...THIS SHOULD REVERSE TONIGH WITH LOSS OF DAYTIME HEATING. && .IND WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ021-028>031- 035>049-051>057-060>065-067>072. WIND CHILL ADVISORY UNTIL 7 AM EST MONDAY FOR INZ021-028>031- 035>049-051>057-060>065-067>072. && $$ PUBLIC...CS AVIATION...JH in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1224 PM EST SUN DEC 21 2008 .AVIATION...18Z TAFS VERY DRY/COLD AIRMASS AND LARGE SCALE SUBSIDENCE BEHIND ARCTIC FRONT HAS LED TO VFR CONDITIONS AT BOTH TAF SITES. SHOULD SEE VFR CONDITIONS CONTINUE AT LEAST THROUGH THE MID AFTN HOURS...ALTHOUGH DEVELOPING CU FIELD MAY ALLOW FOR BKN HIGH END MVFR CIGS. WILL REMAIN OPTIMISTIC WITH SCT020 FOR NOW AND AMEND IF NEEDED. STRONG SFC PRESSURE GRADIENT BEHIND LOW TRACKING INTO THE EASTERN LAKES HAS ALLOWED WINDS TO GUST NEAR 35 KTS. EXPECT THESE STRONG WESTERLY WINDS TO CONTINUE INTO THIS EVENING BEFORE DIMINISHING LATE TONIGHT INTO MONDAY AS A SFC HIGH BUILDS INTO THE MID MS VALLEY. MAIN FCST ISSUE WILL BE EVOLUTION OF LAKE EFFECT SHSN ACTIVITY LATE THIS AFTERNOON INTO TONIGHT AS SECONDARY TROUGH AXIS PIVOTS THROUGH ON BACKSIDE OF DEEP UPPER VORTEX. FLOW WITHIN THE CLOUD BEARING LAYER WILL SHIFT MORE WNW WHICH WILL ALLOW SHSN ACTIVITY AND MVFR SC DECK TO IMPACT FWA/SBN. THERE IS THE POTENTIAL FOR BRIEF LIFR/IFR VIS RESTRICTIONS AT SBN LATE THIS AFTN AND TONIGHT. FOR NOW...WILL CONTINUE WITH MVFR CIG/VIS FCST WITH A TEMPO IFR MENTION THIS EVENING AT SBN. && .PREV DISCUSSION... /ISSUED 1040 AM EST SUN DEC 21 2008/ ..DANGEROUSLY COLD WIND CHILLS...HEAVY LAKE EFFECT SNOW AND INCREASING THREAT FOR POWER OUTAGES CONTINUE TO LOOM... UPDATE... SIGNIFICANT CHANGES MADE TO FORECAST THIS MORNING AND ALL PRODUCTS SHOULD BE UPDATED AND OUT. SUBSIDENCE AND VERY DRY AIR ASSOCIATED WITH ARCTIC INTRUSION HAS CLEARED SKIES ACROSS MOST AREAS EXCEPT WHERE LAKE CLOUDS PERSIST. ADDED SUNSHINE SHOULD HELP INCREASE MIXING TO SOME EXTENT IN LOWER LEVELS AND THIS WILL RESULT IN INCREASED WINDS INTO THIS AFTERNOON. EXPECT CLOUDS TO INCREASE AGAIN LATER TODAY. SURFACE GEOSTROPHIC WIND PLOT SHOWING 50 TO 60 KNOTS AT 12Z UPSTREAM TO EASTERN IA AND WESTERN WI. BUFKIT SOUNDINGS WERE SHOWING POTENTIAL OF UP TO 45 KNOTS FROM INVERSION HEIGHT. GIVEN THE ICING SITUATION AND NUMEROUS POWER OUTAGES ALREADY OCCURRING...DECIDED TO UPGRADE TO A WIND ADVISORY MOST AREAS. HOWEVER...CENTRAL AND NORTHERN AREAS WHERE A LIGHT SNOW OCCURRED AND SNOW COVER ALREADY EXISTS...WENT WITH A WINTER WEATHER ADVISORY FOR ADDED IMPACT OF BLOWING SNOW AND POTENTIAL FOR ADDITIONAL SNOWFALL LATER TODAY AND TONIGHT. THIS PRODUCT COMBINES THE WIND THREAT WITH THE BLOWING SNOW FOR SIMPLICITY OF HEADLINES. NEXT FOCUS WAS ON WIND CHILL CRITERIA. AS WE HAVE BEEN INDICATING LAST FEW DAYS...MODELS HAD NO CLUE ON SEVERITY OF THIS COLD AIRMASS AND ONLY COLLABORATION ISSUES KEPT US FROM GOING COLDER. NOW THAT IT IS HERE AND TEMPS ARE WELL BELOW GUIDANCE...UPGRADES ARE NEEDED FROM WIND CHILL ADVISORY TO WARNINGS. SEVERAL SITES ALREADY AT OR BELOW ZERO WITH TEMPERATURES AND CURRENT WINDS CREATING WIND CHILLS AT WARNING CRITERIA NEAR 25 BELOW ZERO. UPGRADED ALL AREAS TO WARNING THROUGH MONDAY MORNING. HIGHER GUSTS THIS AFTERNOON COULD PUSH VALUES COLDER THAN 30 BELOW IN SOME AREAS AS WE ARE NOT EXPECTING MUCH RECOVERY IN TEMPS. WINDS RELAX SOME TONIGHT BUT LOWS BELOW ZERO EXPECTED SO WIND CHILLS SHOULD REMAIN IN WARNING AREA. IT HAS BEEN AWHILE SINCE WE HAVE EXPERIENCED THESE KIND OF WIND CHILLS. WINTER STORM WARNING WAS LEFT INTACT. AGAIN TO KEEP HEADLINES SIMPLE...WIND ADVISORY AND WIND CHILL ARE COMBINED INTO THE WARNING AND MENTIONED IN BODY. WIND CHILLS ACTUALLY ARE EXPECTED TO BE A BIT MORE MODERATE IN THIS AREA DUE TO WARMER LAKE PLUME AND CLOUDS. HOWEVER WIND SPEEDS COULD BE GREATER NEAR THE LAKE. SHORT TERM... TODAY THROUGH MONDAY NIGHT. .BITTER WIND CHILLS...LAKE EFFECT SNOWSHOWERS AND INCREASING THREAT FOR POWER OUTAGES CONTINUE TO LOOM... ARCTIC COLD FRONT MAKING GOOD PROGRESS WITH TEMPS PLUMMETING BEHIND IT. MOST LOCATIONS GOING FROM MIDDLE 20S TO THE SINGLE DIGITS WITHIN 3 HOURS. ALSO BURST OF STRONGER WIND GUSTS ASSOCIATED WITH THE STG CAA WITH GUSTS IN THE 30 TO 35 KT RANGE. HAS BEEN SOME DISCUSSION ON WIND ADVISORIES FROM SURROUNDING OFFICES...BUT THINK FOR NOW WILL HOLD OFF ON ANYTHING. IF WE CAN GET SOME SUN THIS AFTERNOON AND ALLOW FOR SOME MIXING...COULD BE LOOKING AT THE NEED FOR ONE FOR THE AFTERNOON AND EVE HOURS. WILL DEFER TO DAY SHIFT TO MONITOR. HAVE LOWERED HIGHS TODAY TO BETTER REFLECT THE PUSH OF COLD AIR. STARTING AT 12Z ANTICIPATING TEMPS TO BE WELL INTO THE SINGLE DIGITS WEST TO MID TEENS EAST AS FRONT WILL JUST BE CLEARING THESE AREAS. THEN TEMPS WILL CONTINUE TO SLOWLY FALL. POPULATED WITH RUC40 DATA WHICH SEEMS TO HAVE A GOOD HANDLE ON TRENDS...WHICH WOULD PUT SOME LOCATIONS IN THE SW AREAS NEAR OR EVEN BELOW ZERO BY LATE MORNING. GIVEN UPSTREAM TEMPS ALREADY 1 ABOVE AT ORD AND CORE OF COLDEST 850 MB TEMPS POISED TO PASS OVER THE SW HALF THIS AFTERNOON WITH VALUES IN THE -25 TO -28 C RANGE /15 TO 20 DEGREES BELOW MEANS FOR DECEMBER/...THINK THIS IS REASONABLE AND GRIDS REFLECT THIS. THIS BRINGS ANOTHER CHALLENGE. IF WINDS DO REMAIN UP...THEN THESE SAME AREAS WILL APPROACH OR EXCEED WIND CHILL WARNING CRITERIA. FOR NOW WILL STICK WITH ADVISORY...BUT SPEED UP ONSET TO START WITH PACKAGE RELEASE AND LET DAY SHIFT MONITOR WINDS AND TEMPS FOR POSSIBLE UPGRADE. ALSO HAS HAS BEEN NOTED IN MANY PRODUCTS...ANTICIPATING INCREASED ISSUES WITH POWER OUTAGES AND TREE/POWER LINE DAMAGE AS STRONG WINDS OVERLOAD ALREADY BURDENED LINES AND TREES. POWER HAS ALREADY BEEN FLUCTUATING HERE AT THE OFFICE AND EXPECT THIS TO CONTINUE FOR MANY AREAS WITH ICE STILL AROUND. LAKE EFFECT SNOWSHOWERS WILL QUICKLY KICK IN BEHIND THE FRONT WITH THE BULK OF THE ACTIVITY ACROSS THE FAR NORTHERN PARTS OF THE AREA. WILL CONTINUE WITH WINTER STORM WARNING FOR BERRIEN THROUGH ST JOE COUNTIES IN MICHIGAN. WHILE BEING A BIT OF A PROLONGED EVENT...WIND CHILLS...WINDS...TEMPS AND SNOWFALL WILL ALL LEAD TO ROUGH TRAVEL IN THESE AREAS. BAND STILL LOOKS TO SET UP RATHER NICELY TOWARDS MONDAY MORNING ACROSS THE FAR SOUTHER MICHIGAN COUNTIES AND SINCE THIS HAS BEEN THERE FOR SEVERAL RUNS WILL BLEND WITH GRR AND DTX AND EXPAND LIKELY POPS OUT INTO HILLSDALE CO. WILL KEEP AMOUNTS IN THE 1 TO 2 INCH RANGE IN THESE AREAS FOR NOW. THINGS LOOK TO EASE UP FOR MONDAY AND MONDAY NIGHT TO GIVE A DRY BUT COLD FORECAST BEFORE THE NEXT SYSTEM ARRIVES IN THE LONG TERM. LONG TERM... DIFFICULT FCST PD THROUGHOUT. VRY INTENSE SW TROUGH OVR THE GULF OF AK YDA HAS STEAMED SEWD TO NR COASTAL WA STATE THIS MORNING...BRINGING RARE HEAVY SNOW TO KSEA AND A GOOD INDICATOR OF HOW INTENSE THIS SYS IS. UPSTREAM JET STREAK PER VAPOR LOOKS QUITE INTENSE AS WELL AND WILL AID SYS DIG INTO SWRN ROCKIES TUE. DOWNSTREAM CONDS REMAIN A MESS THOUGH W/INCOMING INTENSE ARCTIC WEDGE AND EVENTUALLY STG LL MSTR RTN OVERTOP RETREATING COLD DOME MID WEEK. 00Z GUIDANCE TAKEN AS A WHOLE TRENDING QUICKER W/PCPN DVLPMNT AND NOW INDICATING SNOW TUE AM AND SEE NO REASON TO ARGUE GIVEN UPR JET SHIFTING THROUGH THE NRN LAKES BY TUE AFTN. PRIMARY DIFFICULTY LIES W/LL THERMAL RESPONSE INTO RETREATING ARCTIC WEDGE. AS NOTED YDA...STILL FEEL MODELS ERODING ARCTIC DOME TOO QUICKLY ESP OVR DEEPER HIGH DENSITY SNOWPACK ACRS NRN PORTION OF CWA YET ON THE OTHER HAND CAN`T DISCOUNT LACK OF SNOW CVR ACRS DOWNSTATE IL/IN. THUS IT SEEMS AT LEAST THE THREAT FOR ANOTHER POTENTIALLY SIG ICING EVENT PSBL TUE NIGHT AND WED ACRS NRN/NW THIRD OF CWA. PRIOR TO THAT...MAINLY SNOW TUE INTO TUE EVENING BFR WARM LYR LEADS TO IP MIX GENERALLY SOUTH OF US 30 AND ZR SOUTH OF US 24. EJECTION OF INTENSE WRN SW LT TUE MORE DISCONCERTING GIVEN DRAMATIC MED RANGE TRENDS W/DEGREE OF SFC DVLPMNT SEEN IN 00Z GFS AND ITS ENSEMBLES. OP GFS/ECMWF SOLUTIONS SIMILAR...BOTH IN INTENSITY AND QUICKER NEWD EJECTION COMPARED W/GFS ENSEMBLES YET CERTAINLY WITHIN THE SCOPE OF POSSIBILITIES. PRIOR FLAT OPEN WV EJECTION SEEN IN 12Z RUNS COMPARABLE W/LATEST WRF 4KM RUN SO UNCERTAINTY IS HIGH. BEST RECOURSE AT THIS POINT IS TO WEIGHT WED PD MORE HEAVILY TWD A MIXED PCPN EVENT XPC PERHAPS FAR NW PER IMPLIED SFC LOW TRACK BUT DO XPC ADDNL SIG FLUCTUATIONS THROUGH THE NXT 36HRS UNTIL THIS SYS GETS FURTHER INTO UPR AIR NETWORK AND SAMPLED BTR. IN THE LEAST...ANOTHER HEAVY PRECIPITATION EVENT LIKELY TO BE REALIZED TUE NIGHT/WED. AFT THAT...PATTN RELOADS AMAZINGLY FAST W/YET ANOTHER INTENSE MID LAT CYCLONE FOR LT WEEK. ADDNL HEADACHES CERTAIN YET WILL SPARE ANY DETAILS FOR THE MOMENT GIVEN THAT TIME RANGE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL WARNING UNTIL 1 PM EST /12 PM CST/ MONDAY FOR INZ003>009-012>018-020-022>027-032>034. WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR INZ013-015-017- 018-020-022>027-032>034. WINTER WEATHER ADVISORY UNTIL 10 AM EST /9 AM CST/ MONDAY FOR INZ003>009-012-014-016. MI...WIND CHILL WARNING UNTIL 1 PM EST MONDAY FOR MIZ080-081. WINTER WEATHER ADVISORY UNTIL 10 AM EST MONDAY FOR MIZ080-081. WINTER STORM WARNING UNTIL 10 AM EST MONDAY FOR MIZ077>079. OH...WIND CHILL WARNING UNTIL 1 PM EST MONDAY FOR OHZ001-002-004-005- 015-016-024-025. WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR OHZ015-016-024- 025. WINTER WEATHER ADVISORY UNTIL 10 AM EST MONDAY FOR OHZ001-002- 004-005. LM...HEAVY FREEZING SPRAY WARNING UNTIL 5 AM EST MONDAY FOR LMZ043- 046. GALE WARNING UNTIL 5 AM EST MONDAY FOR LMZ043-046. && $$ SHORT TERM...FISHER LONG TERM...HOLSTEN UPDATE...LASHLEY AVIATION...STEINWEDEL in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 1212 PM EST SUN DEC 21 2008 .AVIATION... DISCUSSION FOR 18Z TAFS. STRONG AND BITTERLY COLD W-NW FLOW WILL CONTINUE THIS AFTERNOON. PRESSURE GRADIENT WILL GRADUALLY DIMINISH TONIGHT AND MONDAY AS HIGH PRESSURE BUILDS INTO THE MID MISSISSIPPI VALLEY LATER TONIGHT AND EVENTUALLY INTO THE LOWER OHIO VALLEY MONDAY. WINDS MAY TEMPORARILY INCREASE SOME THIS AFTERNOON AS DAYTIME MIXING LEVEL INCREASES. MIE ALREADY REPORTED A WIND GUST UP TO 39 KNOTS. MODEL SOUNDINGS ESPECIALLY NAM SHOWS BROKEN CLOUDS INCREASING THIS AFTERNOON. GFS/RUC ALSO SHOW THIS...BUT NOT QUITE AS STRONG AS NAM AND GFS IS QUICKER TO CLEAR US OUT LATER TONIGHT. WILL GO WITH LATTER SCENARIO AS CURRENTLY NOT MUCH CLOUDS UPSTREAM. THEY MAY TEMPORARILY INCRAESE...THIS SHOULD REVERSE TONIGH WITH LOSS OF DAYTIME HEATING. && .PREV DISCUSSION... /ISSUED 300 AM EST SUN DEC 21 2008/ DISCUSSION... MAIN PROBLEM FOR THE SHORT TERM WILL BE THE WINDS AND TEMPERATURES. VERY STRONG LOW PRESSURE OVER SOUTHERN OHIO MOVING EAST. EXTREMELY TIGHT PRESSURE AND TEMPERATURE GRADIENT MOVING INTO INDIANA. AT INDY HAD A WIND GUST TO 43 MPH AT 130 AM. RUC HAS 48 MPH WINDS AT 2,500 FT THIS AFTERNOON. WITH A GOOD AMOUNT OF SUNSHINE ESPECIALLY DURING THE MORNING THERE WILL BE GOOD MIXING. THIS WILL KEEP WINDS ABOVE ADVISORY LEVELS CENTRAL AND N AND CLOSE ENOUGH IN THE SOUTH. THE WINDS WILL DROP DOWN AFTER SUNSET. ALL OF THE MODELS ARE WAY TO WARM WITH THE TEMPS. THE NAM WHICH IS THE COLDEST AT HUF AT 09Z HAS 20 THEY WILL BE 16 OR MAYBE LOWER. THE NAM 850 MB TEMPS DROP TO -25 THIS AFTERNOON. SO HAVE CUT GUIDANCE HIGHS WAY BACK TODAY. THEY MAY TRY TO REBOUND SOME THIS AFTERNOON BUT WITH COLD AIR SC MOVING IN THIS WILL SLOW THAT ALONG WITH THE SHORTEST PERIOD OF SUNSHINE OF THE YEAR. THIS WILL PUT WIND CHILL VALUES WELL INTO ADVSRY LEVELS. EVEN THOUGH WINDS WILL DECREASE THIS EVENING THEY WILL REMAIN HIGH ENOUGH WITH THE TEMPS JUST ABOVE ZERO TO KEEP THE ADVSRY GOING THROUGH 12Z MONDAY. THE WEDGE OF EXTREMELY COLD AIR WILL MOVE EAST OF INDIANA ON MONDAY. THIS ALONG WITH AT LEAST PARTLY SUNNY WILL ALLOW TEMPS TO REBOUND BUT HIGHS WILL STILL REMAIN IN THE TEENS. MODEL TIME SECS FAVOR SOME CLRG ON MON AS LOW LVL MOISTURE THINS AND SFC HIGH PRES SETTLES ACRS THE OH VLY ALONG WITH A FLAT UPR RIDGE. NICE RETURN FLOW ON TUESDAY AHEAD OF AN APRCHG CD FNT SHOULD BRING SOME LGT SN IN TUES PM AND CHRISTMAS EVE PERHAPS MIXED WITH RN S PER SOUNDINGS AND CRITICAL THICKNESS PROGS. MODELS SUGGESTING MORE PRECIP IN THE EXTENDED THAN EITHER HPC OR THIS MRNGS FCST. GFS AND ECMWF HAVE A LOT OF DIFFERENCES BUT ARE TRENDING TOWARD A PROLONGED PD OF RETURN FLOW AHEAD OF A SLOW MOVING CD FNT. SO...OVERRUNNING SECENARIO PSBL WITH RN/SN MIX SUGGESTED BY THICKNESSES. LEANED A LITTLE MORE TOWARDS THE USUALLY MORE ACCURATE ECMWF AND HAVE PRECIP IN ON CHRISTMAS NGT && .IND WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ021-028>031- 035>049-051>057-060>065-067>072. WIND CHILL ADVISORY UNTIL 7 AM EST MONDAY FOR INZ021-028>031- 035>049-051>057-060>065-067>072. && $$ PUBLIC...HAINES AVIATION...JH in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 330 PM CST SUN DEC 21 2008 .SHORT TERM /TONIGHT/... DEEP UNIDIRECTIONAL NW FLOW OF 40 TO 50 KT STILL SHOWING UP ON SLATER PROFILER AT THIS TIME...AND ALTHOUGH LAPS/RUC SOUNDINGS SHOW THE MIXED LAYER ONLY TO BE ABOUT 2 KFT...WINDS HAVE BEEN PLENTY STRONG AND GUSTY SINCE LATE MORNING. TIME HEIGHTS AND SOUNDINGS SHOW STRONG SUBSIDENCE THROUGH A DEEP LAYER OF THE ATMOSPHERE LIKELY CONTRIBUTING TO THE STRONG WINDS. DESPITE ASOS OBS MAINLY JUST ABOVE 1/4SM VSBY...REPORTS FROM COUNTIES IN THE BLIZZARD WARNING AREA SUPPORT MAINTAINING THE BLIZZARD WARNING THROUGH ITS EXPIRATION AT 00Z. CONSIDERABLE BLOWING AND DRIFTING SNOW AND WHITEOUT CONDITIONS WAS AND STILL IS COMMON. WINDS WILL SLOWLY ABATE AFTER SUNSET AS INVERSION LOWERS AND SURFACE HIGH PRESSURE TO THE WEST SLIDES EAST OVER WEST-CENTRAL IOWA BY 12Z. DANGEROUSLY COLD WIND CHILL VALUES ARE REALLY THE MAIN STORY FOR TONIGHT. TEMPERATURES DROPPING THROUGH THE SINGLE DIGITS BELOW ZERO AND SETTLING BETWEEN 10 BELOW AND 20 BELOW TONIGHT...COMBINED WITH THE WIND WILL YIELD WIND CHILL VALUES 30 BELOW TO 40 BELOW NORTH OF HIGHWAY 92 THROUGH AT LEAST MIDNIGHT...AND ONLY SLIGHT WARMER SOUTH OF THERE. HAVE EXPANDED WIND CHILL WARNING SOUTH TO HIGHWAY 92 TO ACCOUNT FOR THIS. THE WIND DIMINISHING UNDER 10 MPH LATE TONIGHT WILL LIKELY ALLOW THE WIND CHILL HEADLINES TO GO AROUND 4 AM. .LONG TERM /MONDAY THROUGH SUNDAY/... MAIN CONCERNS IN THE LONG TERM CONTINUE TO BE THE STORM SYSTEMS ON TUESDAY AND POTENTIALLY THE END OF THE WEEK AND THE ROLLER COASTER RIDE FOR TEMPS. RELATIVELY BENIGN WEATHER MONDAY...VERY COLD BUT NOT MUCH WIND AND NO PRECIP. BY MONDAY NIGHT AS THE LOW PULLS OFF AND THE NEXT SYSTEM MOVES ON BOARD OVER THE SW U.S. THE FLOW OVER THE CENTRAL CONUS BECOMES STRONGLY ZONAL TO SOUTHWESTERLY BY TUESDAY. THIS SETS THE STAGE FOR STRONG WARM ADVECTION OVER CENTRAL AND SOUTHERN IOWA. MONDAY NIGHT MINS WILL OCCUR SHORTLY AFTER 00Z AND WARM THROUGH THE NIGHT. BOTH THE GFS AND EURO MOVE THE TUESDAY SYSTEM THROUGH AS AN OPEN LONG WAVE TROUGH WITH A PRETTY IMPRESSIVE VORT MAX MOVING ACROSS SOUTHERN/EASTERN IOWA. BOTH MODELS ALSO PRINT OUT IMPRESSIVE QPF TUESDAY NIGHT. THE EURO IS WAY MORE AGGRESSIVE ON PRECIP TUESDAY WHERE THE GFS IS NOT AS AGGRESSIVE. HOWEVER...WITH THIS KIND OF FLOW WE CAN EASILY GET HEAVIER SNOW AND MORE MOISTURE ENTRAINED IN THE SYSTEM. I HAVE BEEFED UP POPS AND QPF WITH THIS SYSTEM THROUGH TUESDAY NIGHT AND LINGERED THE LIGHT SNOW INTO WEDNESDAY. SOME HINT OF A TROWAL WITH THE SYSTEM OVER THE SOUTHEAST SO SNOW AMOUNTS HIGHER THERE TUESDAY NIGHT/WEDNESDAY. TEMPERATURES REMAIN MODERATE THROUGH CHRISTMAS THOUGH I MADE SOME ADJUSTMENTS WITH THE INCREASED SNOWFALL AMOUNTS. AS FOR THE LATE WEEK SYSTEM...THE MODELS ARE ALL OVER THE PLACE WITH THIS SO CONFIDENCE IS STILL RATHER LOW. THE GFS DEVELOPS THIS HUGE LOW OVER THE SOUTHERN PLAINS WITH ANOTHER LONG WAVE TROUGH LIFTING UP OVER THE CENTRAL U.S. THIS SCENARIO PUTS CENTRAL IOWA IN ABOUT 36 HOURS OF SNOW. THE EURO IS ABOUT 12 HOURS FASTER AND MUCH SHARPER WITH THE UPPER TROUGH WHICH DISPLACES THE HEAVIER PRECIP TO THE EAST AND GIVES US ALMOST NOTHING FOR PRECIP. WE WILL ALSO NEED TO CONSIDER MIXED PRECIP WITH THIS SYSTEM AS WARMER AIR WILL BE IN PLACE AND ICE WILL HAVE TO BE CONSIDERED. WITH THE KIND OF DISCREPANCIES OUT THERE I PUT LOW POPS IN FROM FRIDAY THROUGH SATURDAY. BETTER DEFINITION WILL COME AS MODELS CONVERGE SOME. && .AVIATION...21/18Z WINDS HAVE INCREASED RIGHT ON SCHEDULE AS MAX SUBSIDENCE ALOFT MOVES OVER CENTRAL IOWA. A SOLID 40 TO 50 KTS FROM THE SURFACE TO THE TOP OF THE MIXED LAYER WILL CONTRIBUTE TO GUSTS NEAR 40 KTS THROUGH 21-22Z. MVFR CEILINGS HAVE DEVELOPED EITHER FROM A THIN LAYER OF STRATUS OR FROM BLSN...WHICH WILL CONTINUE THROUGH EARLY THIS EVENING. VSBY WILL BE LOCALLY REDUCED TO 1SM OR LESS AT NRN TAF SITES FROM TIME TO TIME...WITH MAINLY MVFR VSBY AT SOUTHERN SITES. THE WIND DIMINISHES AND BACKS TO THE SOUTHWEST OR SOUTH OVERNIGHT AND AFT 12Z. VFR CONDITIONS WILL PREVAIL AFT 03-05Z. && .DMX WATCHES/WARNINGS/ADVISORIES... WIND CHILL ADVISORY UNTIL 4 AM CST MONDAY FOR ADAIR-ADAMS-APPANOOSE-AUDUBON-CASS-CLARKE-DALLAS-DAVIS-DECATUR- GUTHRIE-JASPER-LUCAS-MADISON-MAHASKA-MARION-MONROE-POLK-POWESHIEK- RINGGOLD-TAYLOR-UNION-WAPELLO-WARREN-WAYNE. WIND CHILL WARNING FROM 6 PM THIS EVENING TO 4 AM CST MONDAY FOR BLACK HAWK-BOONE-BREMER-BUTLER-CALHOUN-CARROLL-CERRO GORDO- CRAWFORD-EMMET-FRANKLIN-GREENE-GRUNDY-HAMILTON-HANCOCK-HARDIN- HUMBOLDT-KOSSUTH-MARSHALL-PALO ALTO-POCAHONTAS-SAC-STORY-TAMA- WEBSTER-WINNEBAGO-WORTH-WRIGHT. BLIZZARD WARNING UNTIL 6 PM CST THIS AFTERNOON FOR BLACK HAWK- BOONE-BREMER-BUTLER-CALHOUN-CARROLL-CERRO GORDO-CRAWFORD-EMMET- FRANKLIN-GREENE-GRUNDY-HAMILTON-HANCOCK-HARDIN-HUMBOLDT-KOSSUTH- MARSHALL-PALO ALTO-POCAHONTAS-SAC-STORY-TAMA-WEBSTER-WINNEBAGO- WORTH-WRIGHT. && $$ SHORT TERM/AVIATION...MOYER LONG TERM...FAB ia AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE NEW ORLEANS LA 134 PM CST SUN DEC 21 2008 .AVIATION... RECEIVED PIREP OF LOW LEVEL WIND SHEAR AT KBTR. BASED ON THE REPORT AND AN EXAMINATION OF RUC13 MODEL SOUNDINGS INDICATES THERE IS 10-20 DEGREES AND 15-20 KNOTS OF SHEAR FROM ABOUT 300 FEET TO 100 FEET AGL ON APPROACH TO RUNWAY 4L. THIS IS MARGINAL FOR INCLUSION IN THE TAF...BUT WENT AHEAD AND INCLUDED LLWS THROUGH 23Z AT KBTR ONLY. OTHER TAF LOCATIONS HAVE SLIGHTLY STRONGER PREVAILING SURFACE WINDS...AND RADAR WIND ESIMATES FROM VAD WIND PROFILE AT KMSY AND KLIX SUGGESTS LOWER WINDS IN THE 100-2000 FEET AGL LAYER...SO WILL NOT INCLUDE LLWS AT KMCB...KMSY...AND KGPT. 22 && .PREV DISCUSSION... /ISSUED 1208 PM CST SUN DEC 21 2008/ UPDATE... UPDATED GRIDS AND PRODUCTS TO ELIMINATE MORNING WORDING AND TO REFINE THE HOURLY TEMPERATURES AND DEWPOINTS THROUGH TONIGHT. WAS CONTEMPLATING ISSUING A HARD FREEZE WARNING FOR PORTIONS OF THE NORTH TONIGHT...BUT IT APPEARS TEMPERATURES WILL NOT BE 26 DEGREES OR LOWER FOR MORE THAN AN HOUR OR TWO. AVIATION... VFR CONDITIONS ARE EXPECTED THROUGH MONDAY AS HIGH PRESSURE BUILDS INTO THE AREA. NORTHERLY WINDS 13-18 KNOTS WITH GUSTS AROUND 25 KNOTS WILL CONTINUE AT ALL TAF SITES THROUGH 22-23Z...AND AT KMSY THROUGH 15Z MONDAY. PREV DISCUSSION... /ISSUED 329 AM CST SUN DEC 21 2008/ SHORT TERM... STRONG COLD FRONT MOVING SE AT 30 MPH THIS MORNING AND WILL MOVE OUT OF THE REGION BY MID MORNING. THE TAIL END OF THE FRONT WILL SETTLE NEAR SOUTH TEXAS AND A SFC LOW WILL BEGIN TO FORM AS BAROCLINCITY INCREASES OVER THE WEST GULF. THIS LOW WILL QUICKLY MOVE NE ALONG ANOTHER FRONT MOVING INTO THE AREA WED. PROBLEM AREAS IN THE FCAST WILL REVOLVE AROUND THIS TRANSITION FROM A COLD DRY AIR MASS TO A QUICKLY WARMING MOISTENING ONE. AS MOISTURE FLOWS NORTHWARD WITH THE SFC LOW LATE MONDAY...SOME LIGHT RAIN WILL BEGIN TO FORM OVER THE MOST WESTERN PERIPHERAL PORTION OF THE AREA. CEILINGS WILL BE AROUND 8K` AND SHOULD BECOME DEEP ENOUGH BY 2AM TUE MORNING TO PRODUCE SOME LIGHT RAIN AT THAT LEVEL. MEANTIME THE SFC TEMP WILL BE IN THE MID 30S OVER EXTREME SOUTHERN MISS. THIS IS NOT THE ISSUE...BUT THE DP TEMP IS. DP TEMPS WILL BE RUNNING IN THE TEENS AS RAIN STARTS FALLING THROUGH THE MID LEVELS AT 45-50 DEGREES F. AS THE RAIN FALLS INTO THE DRY AIR NEAR THE SFC VIRGA WILL OCCUR ALONG WITH A MOISTENING AND WARMING OF THESE LOWER LEVELS. SINCE THE LIGHT RAIN FALLS THROUGH AIR AROUND 50 DEGREES BEFORE FALLING INTO THE COLDER AIR IT WILL CAUSE A VERTICAL WARM AND MOISTURE ADVECTION PROCESS. THIS WILL CAUSE WET BULB COOLING THROUGHOUT THE BOUNDARY LAYER AND MAY EVEN CAUSE THE TEMP TO FALL TO FREEZING AT THE TOP OF THE BL. THIS PROCESS IS SO QUICK TO MODIFY THE DRY COOL AIR THAT A VERY SMALL WINDOW OF AN ICE PELLET MIXING WITH RAIN WILL BE POSSIBLE. PLACEMENT AND TIMING OF THIS WILL BE BETWEEN 3AM AND 5AM TUESDAY MORNING OVER EXTREME SOUTHERN MISS AND SOME AREAS ALONG THE LA BORDER. HAZARDOUS DRIVING CONDITIONS OR ANY OTHER PROBLEMS ARE NOT GOING TO ACCOMPANY THIS EVENT. LONG TERM... AS THE SFC LOW MOVES OUT...THE COLD FRONT WILL STALL OVER LA BY WED NIGHT AS ANOTHER STRONGER FRONT MOVES ACROSS THE FOOTHILLS OF THE ROCKIES. THE FRONT MOVES BACK TO THE NW IN THE FORM OF A STRONGLY INVERTED TROUGH. THIS WILL BE A SLOW PROCESS FOR A FEW DAYS STARTING THU. NOW FOR THE WET STUFF. SEVERAL SHORT WAVE DISTURBANCE WILL RUSH THROUGH THE UPPER AND MID LEVEL SW FLOW. SINCE THE OLD FRONT HAS MOVED NORTH...THE AREA WILL BE LEFT WITH PLENTY OF DEEP MOISTURE. THIS WILL HELP SHOWERS AND A FEW THUNDERSTORMS BREAK OUT STARTING THU NIGHT AND LASTING THROUGH FRI NIGHT. PLACEMENT WILL BE THE VARIABLE TO NAIL DOWN OVER THE NEXT FEW DAYS BUT CURRENTLY THIS LOOKS TO BE FROM SE LA THROUGH NORTHERN ALA. THEN THE NEXT STRONG COLD FRONT MOVES IN TO FORCE ALL THE MESS OUT BY NEXT WEEKEND. IT LOOKS TO BE A RELATIVELY WARM AND POSSIBLY WET CHRISTMAS DAY. AVIATION... /12Z TAF ISSUANCE/ STRONG COLD FRONT MOVED THROUGH KMCB AT 0737Z AND KBTR AROUND 0840Z. CURRENT PROGRESS IS MEASURED AT ESE 30KT AND SHOULD MOVE THROUGH KASD AROUND 1030Z...KMSY AROUND 1135Z AND KGPT AROUND 1145Z. A 25NM WIDE BAND OF BROKEN -SHRA PRECEDES THE FRONTAL PASSAGE WITH VERY LITTLE INDICATED AFTER WINDSHIFT. UPSTREAM CONDITIONS SHOW A NARROW BAND OF MVFR CEILINGS JUST BEFORE CLEARING TO VFR HIGH CEILINGS AND NO VISIBILITY RESTRICTIONS GENERALLY NORTH AND WEST OF KAEX-KTVR LINE. THIS IS INDICATED IN TAFS MAINLY AFTER 14Z. 24 MARINE... COLD FRONT EXPECTED TO MOVE OFF THE COAST AFTER 12Z FROM WEST TO EAST AND SHOULD BE SOUTH AND EAST OF THE MISSISSIPPI COASTAL WATERS BEFORE 18Z. STRONG NORTHWEST WINDS EXPECTED TO ONSET SHORTLY AFTER FRONTAL PASSAGE AND CONTINUE THROUGH TONIGHT WITH COLD AIR ADVECTION BEFORE LEVELING OFF SOME MONDAY AFTERNOON. SMALL CRAFT ADVISORY WINDS AND SEAS WITH OCCASIONAL GALE FORCE GUSTS TODAY INTO THIS EVENING. BAROCLINIC RETURN EXPECTED TUESDAY WITH STRONG ONSHORE FLOW TO MAINTAIN HIGH SEAS AND SMALL CRAFT ADVISORY CONDITIONS TUESDAY AND TUESDAY EVENING BEFORE MODERATING WEDNESDAY THROUGH FRIDAY. NEXT COLD FRONT TO AFFECT THE NORTH GULF WATERS EXPECTED LATE SATURDAY NIGHT TO EARLY SUNDAY MORNING. 24 && .PRELIMINARY POINT TEMPS/POPS... MCB 47 26 41 32 / 20 0 10 20 BTR 55 29 45 37 / 20 0 10 20 MSY 56 34 45 42 / 30 0 10 20 GPT 55 31 47 38 / 30 10 10 10 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...SMALL CRAFT ADVISORY UNTIL 6 PM CST MONDAY FOR LAZ066. GM...SMALL CRAFT ADVISORY UNTIL 6 PM CST MONDAY FOR GMZ550-555-570- 575. SMALL CRAFT ADVISORY UNTIL 12 PM CST MONDAY FOR GMZ530. MS...NONE. GM...SMALL CRAFT ADVISORY UNTIL 6 PM CST MONDAY FOR GMZ555-570-575. && $$ la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 430 PM EST SUN DEC 21 2008 .SYNOPSIS... WIDESPREAD LAKE EFFECT SNOW CONTINUES ACROSS THE AREA AT THIS TIME...ALTHOUGH THE BEST SNOW SEEMS TO BE LOCATED ACROSS NORTH CENTRAL UPPER MICHIGAN DUE TO THE STRONG NORTHERLY WINDS. INTERESTINGLY...UPPER MICHIGAN IS THE WARMEST AREA IN THE MIDWEST DUE TO WARM AIR WRAPPING INTO THE U.P. FROM THE EAST. OF EVEN MORE INTEREST...GRB IS CURRENTLY -2C WHILE MNM AND IMT ARE IN THE TEENS ABOVE ZERO. THE ARCTIC BOUNDARY HAS ESSENTIALLY SET UP JUST SOUTH OF THE WI BORDER AND THE NLY FLOW AROUND THE LOW HAS NOT ALLOWED THE COLD AIR TO MOVE INTO THE UP TODAY. A SHORT WAVE OVER NW MN WILL MOVE INTO THE AREA OVERNIGHT AND THROUGH THE REGION MON MORNING. && .SHORT TERM...(TONIGHT AND MONDAY)... LAKE EFFECT CONTINUES ACROSS THE REGION...ALONG WITH SIGNIFICANT BLOWING AND SOME DRIFTING ESPECIALLY NEAR THE SHORELINE. MAIN SHORT TERM FORECAST CONCERNS REVOLVE AROUND THE LES TONIGHT INTO MON MORNING. STRONG NLY FLOW CONTINUES ACROSS THE REGION ALTHOUGH THE FLOW IS SLOWLY STARTING TO BACK AS THE SURFACE LOW MOVES EAST. ALTHOUGH THE NAM SUGGESTS THAT THE FLOW WILL BACK RATHER QUICKLY THIS EVENING...OUR LOCAL WRF AS WELL AS THE RUC13 SUGGEST THAT THIS WIND SHIFT MAY BE A LITTLE SLOWER. A SLOWER BACKING OF WIND MAKES SENSE GIVEN THE STRONG RIDGING THAT WILL LIKELY BUILD INTO AREAS N OF LAKE SUPERIOR OVERNIGHT...SO ACCUMULATIONS ACROSS WARNING AREAS WILL LIKELY BE IN THE 3-7 INCH RANGE AGAIN TONIGHT. AT THIS TIME...THERE IS NO COMPELLING REASON TO MAKE ANY MAJOR CHANGES TO HEADLINES AT THIS TIME. THE BEST BAND OF SNOW WILL LIKELY BE SITUATED ACROSS FAR EASTERN MQT INTO WESTERN ALGER COUNTY THIS EVENING...THEN SLOWLY SHIFT TO THE NE OVERNIGHT AS THE WINDS BACK. EVENTUALLY...THE WINDS WILL TURN TO 330 DEG WHICH SHOULD ALLOW FOR THE HEAVIEST SNOW TO BE ACROSS ALGER COUNTY AND GENERALLY OUT OF MARQUETTE COUNTY. WITH THE WINDS GENERALLY 360 DEG TODAY...KEWEENAW COUNTY RECEIVED VERY LITTLE SNOW. ALTHOUGH THE WINDS WILL SHIFT TO THE NW LATER TONIGHT...THAT STILL IS NOT A FAVORABLE DIRECTION FOR KEWEENAW COUNTY...ESPECIALLY WITHOUT ANY MAJOR CONVERGENCE. IN FACT...KEWEENAW COUNTY MAY SEE BETTER SNOW ON MONDAY AS THE PBL WINDS TURN WESTERLY. AS FOR THE ADVISORY AREAS FOR EASTERN UPPER MICHIGAN...WILL NOT MAKE ANY MAJOR CHANGES TO THOSE AREAS. NORTHERN DELTA COUNTY MAY SEE THE MOST SNOW THIS EVENING WITH THE MAIN BANDING INTO EXTREME NW DELTA COUNTY NEAR ROCK. GOOD NEWS IS THAT THIS BAND WILL END UP SHIFTING EAST THIS EVENING SO ACCUMULATIONS SHOULD BE HELD BELOW WARNING CRITERIA. AM A LITTLE CONCERNED FOR NRN SCHOOLCRAFT COUNTY WITH THE FLOW BECOMING VERY FAVORABLE FOR MULTI-BANDED SNOW INTO AREAS NEAR SENEY ESPECIALLY WELL AFTER MIDNIGHT. AM EVEN A LITTLE MORE CONCERNED FOR THIS AREA GIVEN THE SHORT WAVE CURRENTLY OVER NW MN WILL BE MOVING OVER THE EASTERN UP RIGHT ABOUT THE TIME THE WINDS ALIGN INTO NRN SCHOOLCRAFT COUNTY. PERHAPS THE MAIN LIMITING FACTOR FOR WARNING CRITERIA SNOW IN SCHOOLCRAFT INTO LUCE IS THE NLY FETCH INITIALLY...THEN WHEN THE WINDS DO START BACKING...THEY DO RATHER QUICKLY SO ANY BANDS WILL NOT SET UP FOR ANY EXTENDED PERIOD OF TIME. HOWEVER...LUCE AND NRN SCHOOLCRAFT WILL NEED TO BE MONITORED CLOSELY FOR WARNING AMOUNTS OVERNIGHT INTO MONDAY MORNING. LAST BUT NOT LEAST...TEMPERATURES ARE RATHER INTERESTING THIS AFTERNOON...WITH THE WARMEST AIR ACROSS THE GREAT LAKES CURRENTLY IN UPPER MICHIGAN. THE MAIN ARCTIC AIRMASS HAS GENERALLY MISSED UPPER MICHIGAN TO THE SOUTH. IT/S AMAZING THAT GRB IS -2F...WHILE MNM AND IMT ARE WELL INTO THE TEENS ABOVE ZERO. HOWEVER...IT IS EXPECTED THAT SOME OF THE COLDER AIR IN MN WILL WORK INTO WESTERN UPPER MICHIGAN OVERNIGHT...ESPECIALLY INLAND GOGEBIC AND IRON COUNTIES. WITH WINDS CONTINUING AROUND 10+ MPH OVERNIGHT AND TEMPS AROUND -5F...WILL GO WITH WIND CHILL ADVYS FOR THIS AREA INTO MONDAY MORNING. && .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) MON NIGHT...BACKING WINDS WILL PUSH ANY LINGERING LES OVER THE KEWEENAW OFFSHORE DURING THE EVENING. A PERIODS OF MID LEVEL AND SFC RIDGING WILL KEEP SKIES CLEAR ENOUGH FOR GOOD RADIATIONAL COOLING THROUGH 06Z/TUE ALLOWING TEMPS TO DROP BLO GUIDANCE VALUES INLAND. TUE...MDLS WERE IN GOOD AGREEMENT WITH SCENARIO SUPPORTING LIGHT SNOW AS A BROAD AREA OF DEEP ISENTROPIC ASCENT SPREADS THROUGH THE REGION AHEAD OF MID LEVEL TROUGH MOVING INTO THE NRN PLAINS AND SFC TROF INTO THE UPPER MS VALLEY. MDLS QPF VALUES AROUND 0.10-0.15 WITH SNOW WATER RATIO AVERAGING ABOUT 20/1 WOULD SUPPORT SNOWFALL AMOUNTS IN THE 1 TO 3 INCH RANGE. THIS IS ALSO CONSISTENT WITH THE 1 TO 2 G/GK AVBL MOISTURE DURING A 6 TO 9 HOUR PERIOD OF BEST LIFT. HOWEVER...S FLOW OFF OF LAKE MICHIGAN WITH POTENTIAL FOR LAKE ENHANCEMENT COULD SUPPORT AMOUNTS INTO THE 3-5 INCH...ADVY RANGE FROM ESC TO ISQ. SOME LEFTOVER LIGHT SNOW OR FLURRIES MAY BE POSSIBLE TUE NIGHT WITH CONTINUED WEAK ISENTROPIC LIFT BUT LITTLE IN ADDITIONAL ACCUMULATION IS EXPECTED. WED...ALTHOUGH THE MODELS HAVE CONVERGED A BIT SINCE YESTERDAY...SIGNIFICANT DIFFERENCES REMAIN. THE 12Z ECMWF HAS SHIFTED A BIT SOUTH SE WITH THE SFC LOW TRACK COMPARED TO THE 00Z CYCLE BUT THE GFS CONTINUES TO DEPICT A WEAKER LESS PHASED SHRTWV COMPARED TO THE ECMWF. FOR NOW...WILL LEAN MORE TOWARD THE ECMWF WITH LIKELY POPS ACRS THE CWA. THE GREATEST POTENTIAL FOR SIGNIFICANT ACCUMULATIONS REMAINS ACRS THE E HALF OF THE CWA. SOME LAKE ENHANCEMENT WITH A PERIOD OF NRLY FLOW MAY BE POSSIBLE BUT WILL BE RELATIVELY BRIEF. SO...POTENTIAL FOR LARGE SNOWFALL AMOUNTS N CNTRL WILL BE MARGINAL. THU-SUN...THE FCST REFLECTS THE HPC PREFERRED 00Z ECMWF INTO THE WEEKEND. THE GFS REMAINS SLOWER IN EJECTING A SHRTWV FROM THE SW CONUS AND SHOWS A WEAKER NRN STREAM SHRTWV BRUSHING THE UPPER LAKES FRI OR FRI NIGHT BEFORE LIFTING A STRONG SHRTWV AND SFC LOW INTO THE WRN LAKE SUN. THE ECMWF SUPPORTED BY THE CMC/UKMET EMPHASIZE A MORE A STRONGER PHASED MID LEVEL TROUGH INTO THE UPPER MS VALLEY AND WRN LAKES FRI INTO SAT. PLENTY OF UNCERTAINTY REMAINS WITH THE STRENGTH OR POSITION OF ANY SFC LOW OR FRONTS. IF THE SYSTEM TRENDS TOWARD THE STRONGER 12Z ECMWF...PCPN MIX WOULD AFFECT MUCH OF UPPER MI AS 850 MB TEMP CLIMBS TO NEAR 5C INTO CNTRL UPPER MI. THE 00Z ECMWF KEPT THE WARMER AIR FARTHER SOUTH WHICH WOULD KEEP PCPN MAINLY SNOW. FOR NOW...KEPT MENTION OF RAIN MIX OVER THE FAR SE TIL BETTER AGREEMENT. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... CMX VSBY REMAINS IFR. NORMALLY...NORTHERLY WINDS DO NOT SUPPORT IFR LES...BUT GIVEN THE BLSN IT SEEMS REASONABLE. NORTHERLY WINDS DO NOT NORMALLY SUPPORT WIDESPREAD IFR CONDITIONS...SO THERE MAY BE SOME IMPROVEMENT TO MVFR BEFORE BECOMING IFR AGAIN AS WINDS SHIFT TO THE NW BY THIS EVENING. THE NUMERICAL OUTPUT SUGGESTS STRONGER WINDS THIS EVENING WITH MORE SNOW SO WE COULD SEE SOME LIFR CONDITIONS OVERNIGHT AT CMX BEFORE IMPROVEMENT MONDAY MORNING. AS FOR SAW...THE WORST CONDITIONS WITH SOME LIFR WILL LIKELY BE SEEN IN THE NEXT 3-6 HOURS WITH NORTHERLY WINDS ESPECIALLY AS THE CONVERGENT BAND OVER MQT MOVES SOUTH TO SAW BY 1830Z. AS THE WINDS SHIFT NW THIS EVENING...CONDITIONS WILL IMPROVE TO MVFR AND EVENTUALLY VFR BY MON MORNING. && .MARINE... GALES CONTINUE ACROSS THE LAKE...ALTHOUGH THEY SHOULD DIMINISH OVERNIGHT AS WINDS GRADUALLY TURN WLY AND THEN SLY BY MON NIGHT. WILL NEED TO WATCH FOR GALES IN THE SLY FLOW TUE AFTN INTO EVENING. MODELS ARE NOT IN GOOD AGREEMENT FOR CHRISTMAS EVE SYSTEM...BUT THE 00Z ECMWF SUGGESTS NE GALES POSSIBLE...HOWEVER THE GFS MUCH WEAKER. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ007-013-014- 084-085. WINTER STORM WARNING UNTIL 7 AM EST /6 AM CST/ MONDAY FOR MIZ002>006-009. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ001. WIND CHILL ADVISORY FROM 9 PM THIS EVENING TO 10 AM CST MONDAY FOR MIZ009-010. WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR MIZ010>012. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ MONDAY FOR LSZ162-250-251-263>267. GALE WARNING UNTIL MIDNIGHT EST TONIGHT FOR LSZ265>267. GALE WARNING UNTIL 11 PM EST THIS EVENING FOR LSZ263-264. HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST /12 PM CST/ MONDAY FOR LSZ240>249. GALE WARNING UNTIL 1 AM EST MONDAY FOR LSZ248>251. GALE WARNING UNTIL 2 AM EST MONDAY FOR LSZ242>245. LAKE MICHIGAN... GALE WARNING UNTIL 3 AM EST MONDAY FOR LMZ221-250. && $$ SHORT TERM...MRD LONG TERM...JLB AVIATION...MRD MARINE...MRD mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 358 PM CST SUN DEC 21 2008 .DISCUSSION... /353 PM CST SUN DEC 21 2008/ MAIN FORECAST CONCERNS CONTINUE TO BE WIND CHILLS TONIGHT AND TOMORROW MORNING AND CHANCES OF WINTRY PRECIPITATION TUESDAY INTO WEDNESDAY. TIMING AND PLACEMENT OF CURRENT WIND CHILL ADVISORIES STILL LOOK GOOD...SO HAVE LEFT THEM AS IS. SHORT TERM TEMPERATURE GUIDANCE IS NOT CAPTURING HOW COLD THIS AIRMASS IS AND ALL BUT THE RUC 2-METER TEMPERATURES WERE VERIFYING TOO WARM AT 18Z....PARTICULARLY OVER PART OF NRN MO INTO IA. SO WENT 2-5 DEGREES COLDER THAN GUIDANCE TEMPERATURES TONIGHT...WITH BELOW ZERO LOWS OVER THE NORTHERN CWA AND SINGLE DIGITS ABOVE ELSEWHERE. THE PRESSURE GRADIENT WILL GRADUALLY WEAKEN TONIGHT AS HIGH THE GREAT LAKES LOW MOVES EAST AND HIGH PRESSURE BUILDS INTO THE PLAINS. THE COMBINATION OF SLOWLY DECREASING TEMPERATURES AND WINDS WILL CAUSE WINDS CHILLS TO REMAIN FAIRLY STEADY TONIGHT. ALSO CUT BACK ON HIGHS TOMORROW AND CONTINUED TO SHOW NEAR STEADY OR SLOWLY RISING TEMPERATURES TOMORROW NIGHT AS WARM AIR ADVECTION SETS IN BEHIND HIGH PRESSURE THAT WILL BE QUICKLY MOVING OFF TO THE EAST. NAM/ECMWF/CANADIAN ARE IN PRETTY GOOD AGREEMENT WITH TIMING AND STRENGTH OF TROUGH THAT WILL MOVE ACROSS THE AREA ON WEDNESDAY. EXPECT WINTRY MIX OF PRECIPITATION TO DEVELOP ON TUESDAY AS DECENT LOW LEVEL MOISTURE CONVERGENCE DEVELOPS ON NOSE OF BROAD 65KT LOW LEVEL JET UNDER INCREASING LARGE SCALE ASCENT. FORECAST SOUNDINGS FAVOR A MIX OF FZRA/PL IN THE SRN CWA AND FZRA/PL/SN IN THE NRN CWA TO START...THOUGH DO EXPECT A CHANGEOVER TO RAIN AS TEMPERATURES CLIMB ABOVE FREEZING BY 21Z UP TO I-70. PRECIPITATION WILL THEN BEGIN TO CHANGE BACK TO SNOW AS COLD FRONT MOVES ACROSS THE CWA LATE TUESDAY NIGHT/WEDNESDAY. EXPECT SOME LIGHT ACCUMULATION OF ICE AND SNOW OVER THE AREA BASED ON EXPECTED LIGHT QPF ON TUESDAY. ECMWF/NAM ALSO SHOWING MID LEVEL FRONTOGENESIS SETTING UP OVER NRN MO/SRN IA BY 12Z WEDNESDAY...SO THINK THERE WILL BE A BAND OF ACCUMULATING DEFORMATION ZONE SNOW LATE TUESDAY NIGHT/WEDNESDAY MORNING. PRECIPITATION WILL END OVER THE AREA ON WEDNESDAY AS THROUGH MOVES EAST INTO THE OHIO VALLEY. MEDIUM RANGE MODELS ARE SHOWING GOOD CONTINUITY LATE IN THE WEEK. LEANED TOWARD THE ECWMF/CANADIAN WHICH BRINGS ANOTHER TROUGH ACROSS MO/IL ON SATURDAY COMPARED TO THE SLOWER GFS. TEMPERATURES FAVOR GOING WITH A CHANCE OF RAIN ON FRIDAY WITH A CHANGER OVER TO SNOW LATE FRIDAY NIGHT INTO SATURDAY. BUMPED UP GFS MOS TEMPERATURES ON FRIDAY MORNING WHICH LOOK TOO COLD FOR THE AMOUNT OF WARM AIR ADVECTION. OTHERWISE...GMOS TEMPS LOOK GOOD. BRITT && .AVIATION... /1127 AM CST SUN DEC 21 2008/ FOR THE 18Z TAFS... PRIMARY CONCERN FOR AVIATORS THIS AFTERNOON WILL BE GUSTY NORTHWEST WINDS WHICH WILL CAUSE CROSSWIND ISSUES. SUSTAINED WINDS OF 20-25KTS WITH GUSTS TO 30-35KTS WILL BE COMMON THIS AFTERNOON. ADDITIONALLY...2000-3000FT CIGS WILL DEVELOP OVER MUCH OF THE NORTHERN HALF OF THE BI-STATE REGION AS STRATOCUMULUS MOVES SOUTH FROM THE SNOW FIELDS OVER IOWA AND NORTHERN ILLINOIS. THINK THESE CIGS WILL PERSIST THROUGH EARLY EVENING BEFORE SCATTERING OUT. WINDS WILL ALSO DIMINISH THROUGH THE EVENING...THEN BACK TO THE SOUTHWEST MONDAY MORNING AS THE SURFACE RIDGE DRIFTS EAST OF THE REGION. CARNEY && .LSX WATCHES/WARNINGS/ADVISORIES... MO...WIND CHILL ADVISORY UNTIL 9 AM CST MONDAY FOR KNOX-LEWIS-MARION- SHELBY. WIND CHILL ADVISORY UNTIL 6 AM CST MONDAY FOR AUDRAIN-MONROE- PIKE-RALLS. IL...WIND CHILL ADVISORY UNTIL 9 AM CST MONDAY FOR ADAMS IL-BROWN IL. WIND CHILL ADVISORY UNTIL 6 AM CST MONDAY FOR PIKE IL. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBUQUERQUE NM 934 AM MST SUN DEC 21 2008 .UPDATE... WINTER BEGAN THIS MORNING AT 504 AM MST...AND MOTHER NATURE KNOWS IT. QUICK UPDATE TO LOWER TEMPS ACROSS THE EASTERN PLAINS AS ARCTIC AIR REMAINS ENTRENCHED ACROSS THE AREA. ABUNDANT MID LEVEL CLOUD COVER WILL HAMPER ANY HEATING THIS FIRST DAY OF WINTER...AND RUC13 GUIDANCE SHOWS LEE TROUGHING IN THE EASTERN PLAINS WILL HOLD OFF UNTIL AFTER SUNSET. REMAINING FORECAST LOOKS ON TRACK AT THIS TIME. GUYER && .PREV DISCUSSION...308 AM MST SUN DEC 21 2008... QUIET RIGHT NOW AS ARCTIC COLD FRONT DRAPED FROM THE VCNTY OF THE SANGRE DE CRISTOS TO BETWEEN KLVS AND KCQC AND SOUTHWARD TO THE LOWER PECOS VALLEY. THIS FRONT SHOULD ADVANCE FITFULLY A LITTLE WAYS FARTHER S AND W TODAY...THEN RATHER WEAKLY AND SHALLOWLY MAY EASE THROUGH THE LOWER PASSES/CANYONS OF THE CENTRAL MTN CHAIN INTO THE MIDDLE AND LOWER RIO GRANDE VALLEY TONIGHT. IT SHOULD BEGIN TO WASH OUT MON AS THE FIRST IN THE SERIES OF AT LEAST 3 SEPARATE STORM SYSTEMS BEGINS TO SPREAD SIGNIFICANT AMTS OF SNOW AND RAIN TO NW AND N CENTRAL NM. WITH THE CLOUD MASS ACROSS AT LEAST THE N HALF OF THE STATE THERE IS SOME POTENTIAL THAT THE REMNANT ARCTIC AIRMASS MAY NOT COMPLETELY GET SCOURED OUT ACROSS THE CENTRAL...N CENTRAL SECTIONS AND ON EASTWARD. SO LOWERED A LITTLE SOME OF THE MON MAX TEMPS THESE AREAS. WENT AHEAD AND ISSUED WINTER STORM WATCH FOR ZONES 1...2...4 AND 8 FOR THE 18Z MON TO 00Z WED PERIOD WITH FAIRLY IMPRESSIVE DUMP OF SNOW LIKELY ON THE HIGHER TERRAIN ESPECIALLY NW AND N CENTRAL HIGHER TERRAIN. IN ZONE 1 LATE MORNING AND AFTN TEMPS MON AND POSSIBLY TUE MAY BE TOO WARM TO ALLOW FOR A LOT OF SNOW ACCUM...ESPECIALLY ON PAVEMENT...SO THIS IS THE WEAKEST LINK FOR NOW AMONG THE ZONES INCLUDED IN THE WATCH. ZONE 3 LIKELY TO BE A LITTLE TOO WARM OVERALL...SO NOT INCLUDED IN WATCH SO FAR...THOUGH MON NIGHT INTO EARLY TUE IS A LITTLE PROBLEMATIC. ZONES 5...10...11 AND 14 WILL BE ZONES PERHAPS TO CONSIDER LATER AS START TIME OF EVENT FOR THEM LIKELY NOT TIL LATER MON NIGHT OR EVEN TUE AM. AMOUNTS THERE WILL ALSO BE LESS THAN CURRENT WATCH ZONES AND FOR MAINLY THESE TWO REASONS LEFT THEM OUT OF WATCH FOR NOW. STORM TWO WITH GOOD COVERAGE BUT LIGHTER AMOUNTS FOR THE LATER WED AND EARLY THU PERIOD WITH THIRD ONE PRETTY IMPRESSIVE FOR LATER THU AND FRI. GET YOUR SHOVELS READY. 43 .AVIATION... WIDESPREAD VFR CONDITIONS STATEWIDE TODAY...WITH INCREASING CLOUDINESS SPREADING INTO NORTHWEST NEW MEXICO AS STORM SYSTEM OVER THE PACIFIC NORTHWEST MOVES TO NORTHERN NEVADA. CIGS STEADILY FALLING TO OVC050 NEAR FMN BY 18Z SUNDAY AND TO THE RIO GRANDE BY 22Z SUNDAY WITH MT TOP OBSCURATION OVER THE CENTRAL MOUNTAIN CHAIN. STORM SYSTEM MOVING TO SOUTHEAST COLORADO BY 12Z EARLY MONDAY MORNING WILL BRING GUSTY WINDS TO NORTHEAST NEW MEXICO...WITH GUSTS TO 40 KTS NEAR TEXAS AND OKLAHOMA PANHANDLES DEVELOPING BY EARLY AFTERNOON. NEXT AVIATION DISCUSSION SCHEDULED FOR 22Z. SHY .FIRE WEATHER... NORTHWEST FLOW ALOFT OVER NEW MEXICO WILL BREAK DOWN OVER THE NEXT COUPLE OF DAYS AS CLOSED LOW OVER THE PACIFIC NORTHWEST DIGS RAPIDLY TO THE FOUR CORNERS BY LATE MONDAY. DEEPENING SURFACE LOW OVER EASTERN COLORADO WITH ASSOCIATED COLD FRONT SAGGING SOUTHWARD OVER NEW MEXICO AS DYNAMICALLY ACTIVE TROUGH DIGS INTO THE STATE WILL PRODUCE WIDESPREAD SNOW AND RAIN ACROSS THE STATE BEGINNING LATE MONDAY WITH SIGNIFICANT SNOWFALL NORTH AND WEST...AND HEAVIEST AMOUNTS OVER NORTHERN AND EASTERN RIO ARRIBA COUNTY. TROUGH AXIS SWEEPS INTO WESTERN NEW MEXICO ON TUESDAY AS SURFACE SYSTEM MOVES TO TEXAS PANHANDLE TO ESTABLISH WEST FLOW AND CONTINUING SNOW. NEXT TROUGH UPSTREAM WILL CYCLE INTO WESTERN NEW MEXICO ON WEDNESDAY FOR CONTINUED RAIN AND SNOW...AND NEXT SHORTWAVE IN THE PARADE WILL ROLL IN LATE THURSDAY FOR MORE RAIN AND SNOW. NEXT UPSTREAM TROUGH WILL AMPLIFY AND DIG THROUGH THE FOUR CORNERS ON FRIDAY AS SURFACE LOW DEEPENS OVER EASTERN NEW MEXICO...AND COLD FRONT SINKS SOUTHWARD ACROSS THE STATE LEADING INTO THE WEEKEND. SOME SHORT LIVED CLEARING ON SATURDAY AS AMPLIFYING TROUGH MOVES INTO THE SOUTHERN PLAINS...WITH NEXT UPSTREAM TROUGH ARRIVING OVER THE FOUR CORNERS TO CLOUD UP THE LAST HALF OF THE WEEKEND. WITH COPIOUS MOISTURE IN THE FLOW...EXPECTING NO FIRE WEATHER ISSUES THROUGH THE UPCOMING WORK WEEK AS HUMIDITIES REMAIN ABOVE CRITICAL THRESHOLDS. SHY && .PRELIMINARY POINT TEMPS/POPS UPDATE... FARMINGTON...................... 38 25 41 30 / 5 10 40 50 GALLUP.......................... 39 21 42 28 / 0 5 30 60 GRANTS.......................... 39 20 45 27 / 0 5 20 40 GLENWOOD........................ 58 25 55 32 / 0 0 0 10 CHAMA........................... 31 9 34 17 / 5 20 60 80 LOS ALAMOS...................... 32 17 40 24 / 0 5 20 50 RED RIVER....................... 29 7 30 18 / 5 10 20 70 TAOS............................ 34 11 38 22 / 5 5 20 60 SANTA FE........................ 32 18 42 27 / 0 5 10 50 SANTA FE AIRPORT................ 34 19 41 28 / 0 5 10 50 ESPANOLA........................ 35 17 44 23 / 0 5 10 40 ALBUQUERQUE HEIGHTS............. 41 26 46 33 / 0 5 5 30 ALBUQUERQUE VALLEY.............. 44 21 48 29 / 0 5 5 20 ALBUQUERQUE FOOTHILLS........... 41 22 45 28 / 0 5 5 30 ALBUQUERQUE WEST MESA........... 43 24 47 30 / 0 5 5 30 SOCORRO......................... 47 21 52 29 / 0 5 0 5 SANDIA PARK/CEDAR CREST......... 43 18 41 26 / 0 5 10 40 MORIARTY/ESTANCIA............... 39 16 44 25 / 0 5 0 20 CARRIZOZO....................... 50 21 46 30 / 0 0 5 5 RUIDOSO......................... 42 19 47 29 / 0 0 5 5 RATON........................... 31 12 40 24 / 0 5 5 20 LAS VEGAS....................... 30 15 42 28 / 0 5 5 30 ROY............................. 27 17 39 27 / 0 5 5 10 CLAYTON......................... 29 13 39 28 / 0 5 5 5 SANTA ROSA...................... 32 19 47 33 / 0 5 5 10 TUCUMCARI....................... 32 19 44 34 / 0 5 5 5 FORT SUMNER..................... 33 18 47 30 / 0 5 5 5 CLOVIS.......................... 32 18 43 33 / 0 5 5 5 PORTALES........................ 33 18 45 33 / 0 5 5 5 ROSWELL......................... 38 21 49 34 / 0 5 5 5 && .ABQ WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON FOR THE FOLLOWING ZONES...NMZ001-002-004-008. && $$ GUYER nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 1229 PM EST SUN DEC 21 2008 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL MOVE EAST ACROSS THE LOWER GREAT LAKES THIS MORNING, WHILE A SECOND AND STRONGER LOW DEVELOPS OFF THE NORTHEAST COAST BY MIDDAY. THIS WILL BRING A GENERAL LIGHT TO MODERATE SNOWFALL ACROSS THE REGION, WITH THE HIGHEST SNOWFALL AMOUNTS EXPECTED OVER THE WESTERN MOHAWK VALLEY AND WESTERN CATSKILLS. MUCH COLDER AIR WILL ARRIVE BEHIND THIS SYSTEM TONIGHT, WITH LAKE EFFECT SNOW EXPECTED TONIGHT THROUGH MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... FIRST SFC LOW ACROSS CENTRAL LAKES THIS MORNING, WITH TROF ACROSS THE AREA EXTENDING TO SECOND SFC LOW OFF NEW JERSEY COAST...WHICH IS DEEPENING. STEADY SNOW HAS ENDED ACROSS ERN HALF OF THE FA, WHILE GOOD BAND OF SNOW HANGS ON ACROSS THE EAST AS THE COASTAL LOW TAKES OVER TODAY. RUC DATA SHOWS THIS PRECIP ACROSS THE EAST THRU ABOUT 20Z THIS AFTN BEFORE LIFTING OUT. EVEN THIS LOOKS A BIT SLOW GIVEN RADAR TRENDS AND MODEL TENDENCY TO BE TOO LATE BRINGING PRECIP IN AND OUT WITH THESE SYSTEMS. UPDATED ZONES TO REFLECT THE CURRENT RADAR AND TRENDS, AND TO CANCEL THE ADVISORY IN THE WEST. WILL WAIT A BIT LONGER TO END THE ADVISORY IN THE CENTRAL ZONES, WHERE THE PRECIP IS WINDING DOWN NOW. SO FAR, RECEIVING SOME REPORTS IN THE NORTHEAST OF 5 TO NEARLY 7 INCHES FROM ONEIDA TO OTSEGO COUNTIES. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... TONIGHT...AS SFC LOW LIFTS INTO NRN NEW ENGLAND THIS EVENING SFC PRES DROPS TO 975 MB RESULTING IN STRONG WINDS WITH CONSIDERABLE BLOWING AND DRIFTING SNOW EXPECTED OVER THE ENTIRE REGION. WITH TMPS DROPPING TO AROUND 10 DEGREES WIND CHILLS WILL BE AROUND 10 BELOW ZERO. INITIALLY FLOW NOT FAVORABLE FOR LAKE EFFECT ACROSS FA BUT AFTER 09Z LAKE EFFECT WILL DROP INTO ONEIDA COUNTY WITH SEVERAL INCHES OF SNOW LIKELY BY SUNRISE. MONDAY...LOW LEVEL FLOW CONTINUES TO VEER MONDAY MORNING WITH UNSTABLE LAYER SHOWING 300 DEGREE VECTOR. THROUGH MIDDAY UNSTABLE LAYER VERY DEEP WITH EXTREME INSTABILITY. DURING THE AFTERNOON INVERSION HEIGHT LOWERS ALONG WITH AVAILABLE MOISTURE. FOR NOW, 4 TO 6 INCHES OF SNOW LOOKS POSSIBLE ACROSS ONONDAGA/MADISON AND SOUTHERN ONEIDA COUNTIES. LATER SHIFTS MAY NEED TO ISSUE ADVISORIES. OTHERWISE, A FRIGID DAY WITH MAXES ONLY 15-20 DEGREES AND NORTHWEST WINDS OF 15 TO 25 MPH WITH GUSTS UP TO 35 MPH. SCATTERED SNOW SHOWERS MOST PLACES WITH MINOR ACCUM ACROSS CORTLAND/CHENANGO AND OTSEGO COUNTIES NEAR LAKE BAND. MONDAY NIGHT...FLOW BEGINS TO BACK AS RIDGING BEGINS AT LOW AND UPPER LEVELS. LAKE EFFECT WILL CONTINUE THROUGH EVENING THEN LIFT NORTH TO JUST NRN ONEIDA COUNTY AFTER MIDNIGHT AND PROBABLY NORTH OF THERE BY DAYLIGHT. SEVERAL MORE INCHES OF SNOW IS LIKELY WITH ADVISORY ACCUM POSSIBLE. REST OF AREA WILL REMAIN VERY COLD BUT WINDS WILL BE DIMINISHING. TUESDAY...WITH SFC HI PRES OVER THE MID ATLANTIC REGION, DAY WILL START PARTLY SUNNY WITH INC CLOUDS DURING THE AFTERNOON. SFC LOW PRES IN THE MID WEST WILL BEING THE CHC FOR SNOW DURING THE AFTERNOON FROM I81 WEST. TUESDAY NIGHT...AREA OF LOW PRES WILL STRETCH FROM THE UPR GREAT LAKES SOUTH TO MID WEST BY 12Z WED. DEEP MOISTURE AND ISENTROPIC LIFT WILL SPREAD ACROSS FA WITH HIGH CHC POPS ENTIRE CWA. AFTER 06Z, T85 ABOVE FREEZING ENTIRE FA BUT FAR NORTH PER NAM/GFS. INCLUDED PRECIP MIXING WITH SLEET ALL AREA BUT FAR NRN CWA. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... LONG RANGE CONTS TO SHOW A DVLPG SE RDG AND A RETURN TO MILDER AIR FOR THE FCST AREA. TREND OF THE 12Z GFS AND 00Z EURO WAS TO KEEP THE RDG FLATTER FOR MUCH OF THE PD...SO WHILE WE WILL SEE MUCH MILDER AIR...PERHAPS NOT QUITE AS MILD AS EARLIER RUNS. SO...WILL KEEP THE IDEA OF A TEMP RETURN TO SEASONABLE COLD ON XMAS...AND A SLOW REBOUND OF TEMPS THRU THE END OF THE PD. HPC GUID SEEMED TO CAPTURE THE PTRN AND TREND WELL SO I HAVE USED THAT GUID FOR THE XTNDD GRIDS. && .AVIATION /18Z SUNDAY THROUGH THURSDAY/... STEADY SNOW HAS NOW PULLED EAST OUT OF THE AREA AND OUR TAF SITES ARE RETURNING TO VFR. XPCT VFR OR MVFR CONDS TO CONT THIS AFTN WITH JUST SOME OCNL LGT SNOW SHWRS...AND SOME REDUCTIONS IN VSBY DUE TO BLWG SNOW. OVRNGT...WINDS WILL INCRS AND BLWG SNOW WILL CONT TO CAUSE LWRD VSBY...AS WILL SCT SNOW SHWRS. ON MON...MORE NWLY FLOW WILL BRING THE HEAVIER LES INTO THE AREA...ESP AT RME AND SYR. FURTHER RESTRICTIONS PSBL IN ALL NY TAFS WITH THE INCRSD SNOW SHWRS AND BLWG SNOW. WINDS WILL GRADUALLY BECOME WLY...AND GUSTY WITH SOME GUSTS MORE THAN 30 KTS. MORE OF THE SAME ON MON...XCPT THAT THE WINDS WILL BECOME MORE NWLY AS THE LOW PULLS OUT. OUTLOOK... MON NIGHT...MVFR/IFR SHSN POSSIBLE AT SYR/RME...WITH MOSTLY VFR ELSEWHERE. TUESDAY...VFR EXPECTED. WEDNESDAY-WEDNESDAY NIGHT...MVFR/IFR EXPECTED WITH MIXED PRECIPITATION EVENT. THURSDAY...IMPROVING TO MAINLY VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR PAZ040-048-072. NY...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR NYZ018-036-044-045-056-062. WINTER STORM WARNING UNTIL 4 PM EST THIS AFTERNOON FOR NYZ009- 037-046-057. && $$ SYNOPSIS...JML/RRM NEAR TERM...JML/RRM SHORT TERM...DGM LONG TERM...MLJ AVIATION...DGM/MLJ ny AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 1141 AM CST SUN DEC 21 2008 .UPDATE... NO MAJOR CHANGES MADE TO THE FORECAST THIS MORNING. WILL KEEP THE WIND CHILL WARNING GOING THROUGH THE AFTERNOON AS MOST AREAS STILL CLOSE TO OR JUST MEETING CRITERIA. ALSO ADJUSTED SKY GRIDS AS SKIES ARE CURRENTLY MOSTLY SUNNY TO SUNNY ACROSS THE CWA. NEW AVIATION DISCUSSION BELOW. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH TUESDAY MAIN FCST CHALLENGES FACING THE NEAR TERM THIS MORNING DEALS WITH BITTERLY COLD WIND CHILLS & SNOWFALL THIS MORNING...AND SNOWFALL POTENTIAL MONDAY EVENING/NIGHT. CURRENTLY MSAS IS SHOWING WEAK FRONTAL BOUNDARY DROPPING THROUGH CWA ATTM...WITH WINDS PICKING UP AS SECONDARY PRESSURE RISE BUBBLE APPROACHES THE AREA. CURRENTLY KABR IS GUSTING TO 30KTS...WITH KPIR GUSTING TO 44KTS. WITH TEMPS CURRENTLY WELL BELOW ZERO...WIND CHILL WARNING CRITERIA HAVING NO TROUBLE BEING MET. AS WRAP-AROUND WAA/TROWEL DROPS BACK INTO THE AREA FROM THE NORTH...ANTICIPATE AN UPTICK IN THE SNOW COVERAGE THIS MORNING. HOWEVER...BY 18Z WAA FINALLY BEGINS TO WANE AS THETA-E FORCING BECOMES MORE NEUTRAL. THE DECISION IS THEN WILL THERE BE ENOUGH LIGHT SNOW TO COUPLE WITH THE STRONG WINDS TO JUSTIFY A HEADLINE FOR THE BLOWING SNOW...OR WILL THE WIND CHILL WARNING TAKE CENTER STAGE? ATTM...WILL CONTINUE WITH WIND CHILL WARNING DUE TO HIGHER PERSONAL DANGER...BUT ADD A MENTION OF BLSN AND RESTRICTED VSBYS TO WSW STATEMENT. ALSO...WITH LATEST RUC SHOWING THAT MAIN PRESSURE RISE AXIS WILL REACH THE ERN CWA BY 18Z THIS AFTERNOON...HAVE OPTED TO EXTEND IN TIME THE WIND CHILL WARNING THROUGH 22Z. LOCAL ABRWRF MODEL SHOWS THAT SFC WINDS WILL FALL RATHER FAST THEREAFTER. CWA THEN CATCHES A BRIEF BREAK...ALBEIT COLD...SUNDAY NIGHT INTO MONDAY AS ARCTIC HIGH PASSES THROUGH THE AREA. MEX GUIDANCE VALUES WERE THE COLDEST...AND HAVE UNDERCUT THAT BY ANOTHER DEGREE OR SO. GIVEN STRENGTH OF HIGH PRESSURE...NO CLOUDS FORECAST TO ADVECT IN UNTIL AFT 12Z MONDAY AND DEEP FRESH SNOW COVER...SHOULD BE PRIME CONDITIONS TO MAXIMIZE RADIATIONAL COOLING. FOR MONDAY AFTERNOON THROUGH TUESDAY...NEXT TROF APPROACHES THE CWA. UPPER FLOW TRANSITIONS TO SW AHEAD OF THIS FEATURE...WITH ROBUST WAA MOVING BACK INTO THE REGION. 85H/7H THETA-E FORCING BECOMES PRETTY IMPRESSIVE 00-06Z TIMEFRAME ON TUESDAY...AND 85H-7H Q-VECTOR CONVERGENCE ALSO SHOW RATHER IMPRESSIVE WAA LIFTING INTO THE REGION. BUFKIT SHOWS THAT PRIME SNOW GROWTH REGION MAY BE A TAD HIGH...BUT THERE IS SOME MODEST VALUES OF LIFT THROUGH THE LAYER. HAVE EXPANDED THE AREA OF LIKELY POPS MONDAY NIGHT...AND ALSO GONE WITH A NON-DIURNAL TEMPERATURE TREND MONDAY NIGHT IN ANTICIPATION OF STRONG WAA. AM A BIT WORRIED ABOUT HOW QUICK THE SW PART OF THE CWA WILL MOISTEN UP MONDAY AFTERNOON TO ALLOW FOR PCPN DEVELOPMENT...BUT HAVE INCLUDED SOME SMALL POPS 18Z-00Z MONDAY GIVEN RAPID INCREASE SEEN IN THE 85H-7H LAYER SPEC HUMIDITIES DURING THAT TIME. HAVE ALSO BOLSTERED THE SNOWFALL TOTAL GRID FOR THE 18Z MONDAY THROUGH 12Z WEDNESDAY GRID. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY EXTENDED PERIOD STARTS OFF WITH INVERTED TROUGH AXIS FROM END OF SHORT TERM PERIOD HAVING MOVED EAST INTO MN WITH MOST OF THE PRECIP ALSO HAVING MOVED EAST OF THE AREA. ALTHOUGH...HAVE MAINTAINED SLIGHT CHANCE POPS ACROSS THE EASTERN CWA FOR TUESDAY NIGHT TO ACCOUNT FOR ANY LIGHT SNOW ON THE BACK SIDE OF THIS SYSTEM. HIGH PRESSURE WILL BE SETTLING INTO THE AREA TUESDAY NIGHT INTO WEDNESDAY MORNING WHICH WILL MAKE FOR VERY COLD OVERNIGHT LOWS ONCE AGAIN...WITH TEENS BELOW ZERO QUITE POSSIBLE. AFTER THIS HIGH MOVES OFF TO THE EAST...WAA PATTERN SETS UP FOR THE END OF THE WEEK. GFS STILL HANGING ONTO A WEAK WAVE MOVING ACROSS THE AREA ON THURSDAY WITH VERY LIGHT QPF ACROSS EXTREME EASTERN SOUTH DAKOTA AND INTO MINNESOTA. EC/CANADIAN CONTINUE TO IGNORE THIS FEATURE. LOOKS LIKE POPS HAD BEEN PREVIOUSLY REMOVED FOR THURSDAY AND WILL CONTINUE THIS TREND. TEMPERATURES WILL REMAIN BELOW NORMAL BUT IT APPEARS AS IF THURSDAY WILL BE THE WARMEST DAY OF THE WEEK. WILL BE OPTIMISTIC IN SAYING THE NORTHERN CWA COULD SEE 20 DEGREES WHILE THE SOUTHWESTERN COUNTIES WARM INTO THE MID 20S. && .AVIATION... LATEST VISIBLE SATELLITE SHOWS MOST CLOUD COVER MOVED EAST OF THE AREA. ASOS OBSERVATIONS ARE REPORTING CLOUD LAYERS BUT EVEN THESE REPORTS ARE BECOMING SCATTERED AS WINDS DIMINISH SOMEWHAT AND BLOWING AND DRIFTING SNOW BECOMES LESS OF A PROBLEM. THROUGH THE DAY EXPECT THE REPORTED CLOUDS WILL CONTINUE TO DIMINISH AS WINDS CONTINUE TO DIMINISH. VERY COLD TEMPERATURES AND WIND CHILL VALUES WILL CONTINUE TO MAKE GROUND OPERATIONS PROBLEMATIC. BY THIS EVENING EXPECT A RETURN OF GOOD VFR WITH UNLIMITED CEILINGS AND UNRESTRICTED VISIBILITY. NORTHWEST WINDS WILL DIMINISHING TO 10 TO 15 KTS LATE THIS EVENING. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WIND CHILL WARNING UNTIL 4 PM CST /3 PM MST/ THIS AFTERNOON FOR BROWN-BUFFALO-CAMPBELL-CLARK-CODINGTON-CORSON-DAY-DEUEL- DEWEY-EDMUNDS-FAULK-GRANT-HAMLIN-HAND-HUGHES-HYDE-JONES- LYMAN-MARSHALL-MCPHERSON-POTTER-ROBERTS-SPINK-STANLEY-SULLY- WALWORTH. MN...WIND CHILL WARNING UNTIL 4 PM CST THIS AFTERNOON FOR BIG STONE- TRAVERSE. && $$ UPDATE...PARKIN SHORT TERM...HINTZ LONG TERM...TMT AVIATION...KEEFE WEATHER.GOV/ABERDEEN sd