AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 305 PM MST TUE JAN 30 2007 .SHORT TERM... (TONIGHT AND WEDNESDAY) SHORT TERM CONCERNS ARE TEMPERATURES ALONG WITH SNOW CHANCES AND AMOUNTS. CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING WEST TO NORTHWEST FLOW ALOFT ACROSS THE STATE WITH ONE WEAK SHORT WAVE SHEARING APART AS IT DIVES ACROSS THE GREAT BASIN AS ANOTHER STRONGER SYSTEM CONTINUES TO DIVE OUT OF CENTRAL CANADA AND ACROSS THE NORTHERN ROCKIES ATTM. WATER VAPOR ALSO INDICATING SUBTROPICAL MOISTURE STREAMING ACROSS THE DESERT SOUTHWEST AHEAD OF OLD UPPER LOW ACROSS THE NORTHERN BAJA REGION. MODELS IN FAIR AGREEMENT WITH WEATHER DETAILS WITH INCREASING WESTERLY FLOW ALOFT ACROSS THE STATE TONIGHT AS CENTRAL CANADIAN SYSTEM AND ASSOCIATED 100+ KT JET CORE DIVES ACROSS THE NORTHERN GREAT BASIN CARVING OUT A BROAD TROUGH ACROSS THE NORTHERN ROCKIES TONIGHT. THE BROAD TROUGH ALOFT CONTINUES TO SLOWLY MOVE ACROSS THE STATE THROUGH THE DAY ON WEDNESDAY...WITH TROUGH AXIS PROGGED ACROSS CENTRAL COLORADO AT 00Z THU. FOR TONIGHT...INCREASING MOISTURE AND WEST TO SOUTHWEST FLOW PROGGED ACROSS THE CENTRAL AND SOUTHWEST MTS THROUGH THE OVERNIGHT PERIOD WITH BEST MOISTURE ACROSS THE EASTERN SAN JUAN MTS AND SOUTHERN TIER ZONES WITH PROXIMITY TO SUBTROPICAL PLUME. OROGRAPHIC SNOW MODEL YIELDING BETWEEN 2-4 INCHES ACROSS THE EASTERN SAN JUAN MTS OVERNIGHT AND ANOTHER 3-6 INCHES ON WEDNESDAY WITH INCREASING ASCENT AHEAD OF BROAD TROUGH...HAVE ISSUED A SNOW ADVISORY FROM 06Z WED THROUGH 06Z THU FOR ZONES 66 AND 68. LIGHT SNOW EXPECTED TO DEVELOP LATE TONIGHT ACROSS THE CENTRAL MTS AS WELL WITH INCREASING WESTERLY FLOW...THOUGH AMOUNTS TO REMAIN BELOW ADVISORY CRITERIA AT LEAST UNTIL LATER WEDNESDAY. OVERNIGHT LOWS TO REMAIN A CHALLENGE WITH DEVELOPING LEE TROUGHING ACROSS THE PLAINS AND SOME INCREASING HIGH CLOUDS TO HELP KEEP TEMPS UP...HOWEVER DO BELIEVE THERE WILL BE A WINDOW THIS EVENING WHERE COLD AND SNOW COVERED AREAS ACROSS THE LOWER ARKANSAS AND SAN LUIS VALLEY WILL TANK BEFORE STEADYING OUT OR WARMING INTO THE EARLY MORNING. WEDNESDAY...PASSING TROUGH SENDS ANOTHER FRONT AND RE-ENFORCING SURGE OF COLD AIR ACROSS EASTERN COLORADO EARLY WEDNESDAY MORNING...WITH FRONT MOVING ACROSS THE PALMER DVD BETWEEN 15Z AND 17Z AND ACROSS THE REST OF THE PLAINS BY EARLY AFTERNOON. WITH LIFT AND MOISTURE INCREASING ACROSS THE REGION AHEAD OF TROUGH AXIS HAVE GONE WITH LIKELY POPS ACROSS MOST OF THE HIGHER TERRAIN AND IMMEDIATE ADJACENT PLAINS AND MAINLY CHANCE POPS ACROSS THE FAR EASTERN PLAINS. MODEL CROSS SECTIONS INDICATING GOOD DENDRITIC GROWTH POTENTIAL WITH TEMPS BETWEEN -14C AND -20C WITHIN THE MOIST LAYER...WITH LATER SHIFTS POSSIBLY HOISTING HIGHLIGHTS ACROSS THE CENTRAL AND EASTERN MTS WITH SNOW ACCUMS BETWEEN 4-8 INCHES POSSIBLE. WITH THE FRONT MOVING ACROSS THE PLAINS IN THE MORNING WILL LIKELY SEE HIGHS BY THE LATE MORNING WITH DECREASING TEMPERATURES THROUGH THE AFTERNOON. -MW .LONG TERM... (WED NIGHT THROUGH TUE) ...WINTRY WEATHER WILL CONTINUE THROUGH AT LEAST SUN... ...PREPARE NOW FOR EXTREMELY COLD TEMPERATURES FRI-WEEKEND... WED NIGHT AND THU...THE COMBINATION OF A LONGWAVE TROUGH AND YET ANOTHER COLD FRONTAL SURGE SHOULD BRING THE POTENTIAL FOR FLUFFY SNOWFALL AND COLD TEMPERATURES. H7 TEMPERATURES ARE FORECAST TO RANGE FROM -12C TO -15C. SHOULD SEE PLENTY OF SYNOPTIC SCALE ASCENT TO SQUEEZE OUT SNOWFLAKES FROM THE CLOUD COVER. COULD SEE ANOTHER 3-5 INCHES OVER THE MOUNTAINS AND 1-3 INCHES ACROSS THE LOWER ELEVATIONS OF SOUTH CENTRAL AND SOUTHEAST CO. MIGHT NEED AN ADVISORY FOR OUR EASTERN CO MOUNTAINS AND ADJACENT I-25 CORRIDOR THROUGH WED EVENING...IF THE POTENTIAL SNOW EVENT STILL LOOKS GOOD. IT APPEARS THE PRECIPITATION POTENTIAL SHOULD DIMINISH LATE WED NIGHT AND COULD PICKUP AGAIN AROUND THE CONTINENTAL DIVIDE THU AFTERNOON. THERE COULD BE A BRIEF RESPITE OF THE FLUFFY SNOW POTENTIAL ON THU UNTIL THE NEXT WEATHER SYSTEM TAKES AIM FOR THU NIGHT THROUGH FRI NIGHT. I HAVE INCREASE POPS TO CATEGORICAL ACROSS THE SOUTHWEST MOUNTAINS HIGHER TERRAIN WED EVENING GIVEN THE SNOW ADVISORY. ALSO...INCREASED POPS TO HIGH "CHANCE" AND "LIKELY" FOR THE REMAINDER OF THE MOUNTAINS AND I-25 CORRIDOR FOR WED EVENING. DECREASED OR REMOVED POPS FOR THU...BUT MAINTAINED SOME LOW POPS AROUND THE CONTINENTAL DIVIDE. FRI THROUGH SUN...DEEP LONGWAVE TROUGH EXTENDS FROM THE POLAR LOW OVER CENTRAL CANADA INTO THE CENTRAL ROCKIES. THERE HAS BEEN RELATIVELY GOOD CONSISTENCY ON THIS PATTERN DEVELOPING FOR LATE THIS WEEK INTO THE WEEKEND. FOLLOWED THE 06Z/30 DGEX GIVEN THE FINER TERRAIN RESOLUTION. H7 TEMPERATURES ARE PROGGED TO RANGE FROM -18C TO -28C FRI AND SLIGHTLY WARMING THROUGH THE WEEKEND. HIGH AND LOW TEMPERATURES WILL LIKELY BE IN THE SUB-ZERO VALUES FOR OUR MOUNTAINS AND HIGH VALLEYS THROUGH THE WEEKEND. ALSO...THE SOUTHEAST CO PLAINS WILL RANGE FROM SUB-ZERO VALUES INTO THE TEENS. FRI COULD BE A BRUTAL DAY. GIVEN THE POTENTIAL SYNOPTIC ASCENT AND THERMAL STRUCTURE PROJECTED FOR FRI-SAT...HIGH SNOW RATIOS WILL BE LIKELY 20-1 TO 40-1...SO JUST A MINUTE AMOUNT OF QPF COULD PRODUCE 1-6 INCHES OF FLUFFY SNOW. INCREASED POPS TO HIGH "CHANCE" FOR THE MOUNTAINS AND I-25 CORRIDOR ON FRI...AND CONTINUED "SLIGHT CHANCE" TO NO MENTION OVER THE WEEKEND. WHILE WIND SPEEDS WILL NOT BE ALL THAT STRONG...IT WILL NOT TAKE MUCH WIND SPEED TO DROP THE WIND CHILL VALUES GIVEN THE EXTREMELY COLD TEMPERATURES. WIND CHILL READINGS OF -25F TO -35F IN THE MOUNTAINS AND -20F TO 0F WILL BE COMMON FRI THROUGH THE WEEKEND. MON AND TUE...MEDIUM RANGE MODELS PROJECTING NORTHWEST FLOW TO DEVELOP OVER THE ROCKIES AS THE EXTREMELY COLD LONGWAVE TROUGH MIGRATES EASTWARD. A BIG CHALLENGE IF AND WHEN THE MODIFIED ARCTIC AIR MASS WILL RECEDE ACROSS EASTERN CO. AGAIN...FOLLOWED THE 06Z/30 DGEX FINER TERRAIN RESOLUTION MODULE. WILL PLAY A MODERATING TEMPERATURE TREND...EXCEPT FOR THE LOWER AR RIVER VALLEY IN EXTREME SOUTHEAST CO GIVEN THE 1-2 FEET OF SNOW PACK...AND POSSIBLY MORE...THAT WILL BE OVER THIS AREA. MOS/HPC GUIDANCE HAS BEEN 10-20 DEGREES TOO WARM IN THESE DENSE SNOW PACK AREAS. IT HAS BEEN SEVERAL WEEKS SINCE KLAA WAS 35F OR GREATER...SO WILL KEEP TEMPERATURES ON THE COLD SIDE UNTIL THEY REACH ABOVE 35F. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... SNOW ADVISORY FROM 11 PM THIS EVENING TO 11 PM MST WEDNESDAY FOR COZ066-068. && $$ 23/17 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 309 PM MST MON JAN 29 2007 .SHORT TERM... (TONIGHT AND TUESDAY) MAIN FORECAST CHALLENGE WILL CONTINUE TO BE TEMPERATURES... ESPECIALLY OVER SNOW PACK...AND THE POTENTIAL FOR SNOWFALL LATER TONIGHT AND TUESDAY. CURRENTLY...BLAZING SUNSHINE ACROSS CO AND MUCH OF THE CENTRAL ROCKIES. TEMPERATURES CONTINUE TO STRUGGLE TO WARM OVER THE DENSE SNOW PACK AND VALLEYS DESPITE THE FULL SUNSHINE. KLAA AND KALS ARE STRUGGLING TO REACH 20F EARLY THIS AFTERNOON. LATEST WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES SHOWED A CLOSED LOW JUST OFF THE CA COASTLINE AND THE SOUTHERN JET STREAM ACROSS OLD MEXICO INTO THE SOUTHERN PLAINS. MEANWHILE...ANOTHER NORTHERN STREAM UPPER LEVEL JET STREAK WAS MOVING SOUTH-SOUTHEAST OUT OF WESTERN CANADA INTO ID/MT. THERE IS SOME MOISTURE ASSOCIATED WITH THIS FEATURE. THERE IS A COUPLE OF SNOW SHOWERS DEVELOPING WITH A WEAK SHORTWAVE TROUGH ACROSS NERN UT...SWRN WY...AND NWRN CO EARLY THIS AFTERNOON. TONIGHT AND TUESDAY...THE 12KM WRF AND 40KM GFS ARE LIKE NIGHT AND DAY IN TERMS OF QPF BEING GENERATED LATER TONIGHT AND TUESDAY. THE 12KM WRF PRINTS OUT RELATIVELY LIGHT AND SPARSE QPF...WHILE THE GFS HAS A LITTLE BROADER COVERAGE OF QPF. BOTH MODELS ARE SHOWING VERY LITTLE IMPLIED SYNOPTIC SCALE ASCENT TO FOCUS ON QPF BULLSEYES ACROSS OUR AREA. THERE IS A HINT OF SOME MIDLEVEL FRONTOGENETICAL IMPLIED UPWARD VERTICAL MOTION...BUT IT GOES IN AND OUT OF THE MODEL RUNS THROUGH TIME. LAPSE RATES IN THE "MOIST" LAYER IS FORECAST TO BE 7-8 C/KM AND MUCH OF THE "BEST" MOISTURE IS NEAR THE SFC TO H7. IF WE CAN JUXTAPOSE THE MIDLEVEL FRONTOGENETICAL UPWARD FORCING... INSTABILITY...AND ANY OROGRAPHICS...THEN IT COULD SQUEEZE OUT SOME SNOWFLAKES LATER TONIGHT AND TUESDAY. WHERE EXACTLY TO PLACE THE HIGHER POPS IS A CHALLENGE. WILL TWEAK POPS UP A LITTLE FOR TELLER AND EL PASO COUNTIES LATER TONIGHT BASED ON BOU/S FORECAST. OTHERWISE...NOT PLANNING TO CHANGE THE FORECAST MUCH GIVEN MUCH UNCERTAINTY. WONDERING IF THIS EVENT WILL BE MUCH LIKE SAT/S SOMEWHAT NON-EVENT EXCEPT FOR SOME VERY LOCALIZED SPOTS NEAR OUR ERN MOUNTAINS(E.G. 1-2 INCHES). IF THE SNOW CAN MANAGE TO BE CREATED...THEN IT SHOULD BE PRETTY FLUFFY CONSIDERING THE THERMAL STRUCTURE AND INSTABILITY. 20-1 RATIOS WOULD BE COMMON AND RESULTING IN 1-3 INCHES WITH LOW WATER CONTENT. WILL ADD SOME PRECIPITATION INTENSITY VALUE TO THE FORECAST SINCE THE POTENTIAL EVENT WOULD BE LIGHT SNOW OR FLURRIES AT BEST TONIGHT. TEMPERATUREWISE...MODEL MOS GUIDANCE CONTINUES TO BE HORRIBLE OVER THE SNOW PACK/VALLEY AREAS. PLAN TO UNDERCUT MOS SEVERAL DEGREES FOR KLAA...KLHX...AND KALS. ON TUESDAY...ANOTHER WEAK COLD FRONT SHOULD RE-ENFORCE THE COLD AIR ACROSS MUCH OF S CNTRL AND SE CO. METZE .LONG TERM... (TUESDAY NIGHT THROUGH MONDAY) LONG TERM CONCERNS REMAIN TEMPERATURES AND TIMING PRECIP CHANCES AS OCCASIONAL SHORTWAVES AND COLD FRONTS MOVE ACROSS THE REGION. TUESDAY NIGHT-WEDNESDAY NIGHT...LATEST MODELS COMING CLOSER ON NORTHERN AND SOUTHERN STREAM DETAILS WITH INCREASING WEST TO NORTHWEST FLOW ALOFT ACROSS THE AREA TUESDAY NIGHT AND WEDNESDAY AS NORTHERN STREAM UPPER TROUGH SWEEPS ACROSS THE ROCKIES. MOVEMENT OF NORTHERN STREAM SYSTEM KEEPS THE SUBTROPICAL JET AND WEAKENING OLD NORTHERN BAJA UPPER LOW WELL SOUTH OF THE STATE...AND ALSO SENDS COLD FRONT AND RE-ENFORCING SHOT OF COLD AIR ACROSS EASTERN COLORADO WEDNESDAY. AT ANY RATE...WITH PROXIMITY TO SUBTROPICAL MOISTURE AND LIFT ALONG WITH DEVELOPING OROGRAPHIC FLOW...SHOULD SEE SNOW DEVELOPING ACROSS THE SOUTHWEST MTS OVERNIGHT TUESDAY WITH 4 TO 8 INCHES POSSIBLE THROUGH WEDNESDAY EVENING. SHOULD SEE LIGHT SNOW DEVELOPING ACROSS THE CENTRAL MTS TUESDAY NIGHT AND WEDNESDAY AS MOISTURE AND LIFT INCREASES AHEAD OF TROUGH...THOUGH ACCUMULATIONS LOOK TO STAY BELOW ADVISORY LEVELS ATTM. MODELS ALSO IN DECENT AGREEMENT OF SNOW DEVELOPING ACROSS THE EASTERN MTS AND PLAINS WEDNESDAY AFTERNOON AND EVENING AS FRONTOGENETICAL FORCING COMBINES WITH INCREASING LOW LEVEL MOISTURE AND UPSLOPE BEHIND PASSING FRONT. WITH TEMPS PROGGED BETWEEN -14C AND -20C WITHIN THE MOISTURE LAYER...COULD SEE SEVERAL INCHES OF FLUFFY ACCUMULATIONS BY EARLY THURSDAY MORNING. THURSDAY-SATURDAY...NORTH TO NORTHWEST FLOW INCREASES AGAIN THROUGH THE DAY THURSDAY AS NEXT 140+ KT JET CORE DIVES OUT OF CANADA AND ACROSS THE NORTHERN ROCKIES. AGAIN MODELS IN FAIR AGREEMENT WITH SLIGHT WARMUP AND DRIER CONDITIONS ACROSS EASTERN COLORADO THURSDAY BEFORE TROUGH AND ASSOCIATED COLD FRONT MOVES ACROSS THE STATE ON FRIDAY. HAVE KEPT BEST POPS ACROSS THE CENTRAL MTS THURSDAY WITH INCREASING SNOW CHANCES ACROSS THE EASTERN PLAINS THURSDAY NIGHT AND FRIDAY WITH PASSING FRONT. HAVE GONE WELL BELOW CURRENT MOS GUIDANCE FOR HIGHS...AND IF LATEST MODELS ARE CORRECT WITH H7 AND H85 TEMPS BETWEEN -18C AND -24C AND -8C AND -16C RESPECTIVELY...SOME AREAS WILL STRUGGLE TO GET OUT OF THE SINGLE DIGITS ON FRIDAY. WITH MODERATE NORTHWEST FLOW CONTINUING ON SATURDAY...HAVE LOWERED FORECAST TEMPS ON SATURDAY AS WELL...WITH BEST POPS ACROSS THE CENTRAL MTS WITH CONTINUED OROGRAPHICS. SUNDAY-MONDAY...HAVE FOLLOWED HPC GUIDANCE THROUGH THE PERIOD WITH MARKED WARMING POSSIBLE ACROSS THE REGION AS UPPER LEVEL RIDGING BUILDS INTO THE STATE. -MW && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 17/23 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1045 AM CST MON JAN 29 2007 .DISCUSSION... UPDATING FORECAST TODAY STRONGER WSW WINDS TO BRISK LEVELS. OTHERWISE REST OF FORECAST LOOKS ON TRACK AND ONLY TWEAKED THE HOURLY GRIDS TODAY. AFTER A PERIOD OF SUNSHINE THIS MORNING...WILL SEE CLOUDS INCREASE AGAIN ESPECIALLY NW AREAS THIS AFTERNOON WHERE CHANCE OF FLURRIES. HIGHS CLOSER TO NORMAL IN THE LOWER 30S...EXPECT UPPER 20S NORTH OF I-74. BRISK WSW WINDS 15 TO 25 MPH AND GUSTING AROUND 30 MPH...SIMILIAR TO PAST FEW DAYS. 16Z/10 AM SURFACE MAP SHOWS 1030 MB HIGH PRESSURE ACROSS SOUTHERN MS WHILE 1010 MB LOW PRESSURE OVER FAR NW WI. THIS LOW HAD A WARM FRONT DROPPING SOUTHWARD ACROSS IL WHILE ITS COLD FRONT WAS OVER SE MN FAR NW IA AND SE NEBRASKA. BRISK WSW WINDS 15 TO 25 MPH ACROSS IL WITH GUSTS OF 25 TO 30 MPH...EVEN 34 MPH GUST AT DANVILLE. AREA OF LIGHT SNOW EXIT EASTCENTRAL IL EARLY THIS MORNING WHILE LARGE BREAK IN THE CLOUD COVER OVER CENTRAL IL. TEMPS MODERATED INTO THE 20S WITH COOLEST READINGS NE. ALOFT A 517 DM 500 MB CUTOFF LOW WAS OVER THE UPPER MS VALLEY NEAR THE WI/MN BORDER WITH A BROAD UPPER LEVEL TROF EAST OF THE ROCKIES. RUC AND NAM/WRF MOVE LOW PRESSURE INTO LOW MI THIS EVENING WITH ITS ASSOCIATED COLD FRONT MOVING SE ACROSS IL THEN. MOST OF THE LIGHT SNOW WILL STAY NORTH OF CENTRAL IL THIS AFTERNOON WITH FLURRIES POSSIBLE LATER THIS AFTERNOON NW OF LINCOLN. CLOUDS OVER IOWA WILL SPREAD SE ACROSS CENTRAL IL DURING THIS AFTERNOON AS SKIES BECOME MOSTLY CLOUDY WITH NW AREAS BECOMING CLOUDY. WSW WINDS AND SOME SUNSHINE SHOULD HELP ELEVATE TEMPS INTO THE LOWER 30S MOST AREAS THIS AFTERNOON WHICH IS CLOSE TO NORMAL FOR LATE JAN. .PREV DISCUSSION... BELOW NORMAL TEMPERATURES WILL CONTINUE FOR THE NEXT 7 DAYS...WITH PERIODIC CHANCES FOR LIGHT SNOW. ONE FAST-MOVING DISTURBANCE WILL SWING THROUGH THE REGION TONIGHT...WHILE A SECOND WILL COME THROUGH WEDNESDAY NIGHT. MAIN CONCERNS WILL BE POPS AND MINOR SNOW ACCUMULATIONS WITH THESE WEAK SYSTEMS. 06Z SURFACE ANALYSIS SHOWS LOW PRESSURE CENTERED OVER NORTHERN MINNESOTA...WITH WARM FRONT EXTENDING SOUTHWARD INTO KANSAS. COLD FRONT ASSOCIATED WITH THE SYSTEM IS BEGINNING TO DROP SOUTHWARD INTO THE DAKOTAS. ALOFT...WESTERN CONUS REX BLOCKING CONTINUES...WITH LARGE-SCALE TROUGHING EAST OF THE ROCKIES. A SERIES OF WEAK DISTURBANCES CONTINUE TO DROP SOUTHWARD OUT OF CANADA IN BROAD NORTHWESTERLY FLOW PATTERN ACROSS THE MIDWEST. ONE WAVE IS EVIDENT IN WATER VAPOR IMAGERY ACROSS IOWA...WHILE A SECOND MORE POTENT WAVE IS DROPPING INTO NORTH DAKOTA. SHORT TERM...TODAY THROUGH WEDNESDAY... LOW PRESSURE WILL TRACK E/SE TODAY...REACHING CENTRAL MICHIGAN BY 00Z TUE. BEST LIFT AND UPPER SUPPORT FOR WAA SNOWFALL AHEAD OF THE SYSTEM WILL LARGELY STAY NORTH OF CENTRAL ILLINOIS TODAY...WITH PERHAPS A FEW FLURRIES REACHING THE FAR NORTHERN KILX CWA. LATEST SATELLITE LOOPS INDICATE A SWATH OF MID-LEVEL CLOUDS ASSOCIATED WITH THE WARM FRONT MOVING EASTWARD ACROSS EASTERN IOWA/WESTERN ILLINOIS. MEANWHILE FURTHER UPSTREAM...SKIES PARTIALLY CLEAR ACROSS WESTERN IOWA. THINK THERE WILL BE AT LEAST PARTIAL SUNSHINE THIS MORNING...BEFORE CLOUDS BEGIN TO QUICKLY INCREASE FROM THE WEST THIS AFTERNOON. WITH A LITTLE SUNSHINE...ALONG WITH SW LOW-LEVEL FLOW...TEMPS WILL REBOUND NICELY FROM CHILLY MORNING LOWS IN THE SINGLE DIGITS AND TEENS. WILL FOLLOW THE FWC NUMERIC GUIDANCE MOST CLOSELY AS IT HAS BEEN SUPERIOR FOR THE PAST FEW DAYS...TAKING HIGHS TODAY MAINLY INTO THE LOWER 30S. SECOND STRONGER WAVE CURRENTLY OVER NORTH DAKOTA WILL APPROACH THE AREA THIS EVENING...SPREADING LIGHT SNOW ACROSS CENTRAL ILLINOIS. MODELS IN GOOD AGREEMENT WITH THE TRACK/STRENGTH OF THIS SYSTEM...WITH THE NAM-WRF BEING A BIT MORE BULLISH WITH QPF/SNOW ACCUMULATIONS THAN THE GFS. BASED ON CURRENT OBS ACROSS THE DAKOTAS SHOWING VSBYS AS LOW AS 1/2SM AT TIMES...THINK A LIGHT ACCUMULATION OF SNOW IS IN ORDER ACROSS PART OF THE AREA TONIGHT. PATH OF THE VORT MAX SUGGESTS THE BEST BET FOR MEASURABLE SNOW WILL BE ACROSS THE NORTHERN TWO-THIRDS OF THE KILX CWA. A COUPLE TENTHS OF AN INCH WILL BE LIKELY IN THIS AREA...WITH A NARROW CORRIDOR OF ACCUMULATIONS OF UP TO ONE INCH STRETCHING ALONG AND JUST SOUTH OF I-74. FURTHER SOUTH...LITTLE OR NO SNOW WILL FALL SOUTH OF I-70. COLDER AIR WILL BE DRAWN SOUTHWARD INTO THE AREA BEHIND THE DEPARTING SYSTEM ON TUESDAY...WITH HIGHS ONLY CLIMBING INTO THE LOWER TO MIDDLE 20S. AFTER THAT...A SLIGHT WARM-UP WILL BE ON TAP FOR WEDNESDAY...AS YET ANOTHER FAST-MOVING SYSTEM APPROACHES FROM THE WEST. WILL MAINTAIN LOW POPS ACROSS THE ILLINOIS RIVER VALLEY WEDNESDAY AFTERNOON...WITH BULK OF PRECIP NOT ARRIVING UNTIL WEDNESDAY NIGHT. MUCH LIKE THE SYSTEM APPROACHING FOR TONIGHT...THIS ONE MAY PRODUCE A LIGHT ACCUMULATION OF SNOW ACROSS CENTRAL ILLINOIS BEFORE QUICKLY EXITING THURSDAY MORNING. LONG TERM...THURSDAY THROUGH SUNDAY... NOT TOO MANY CHANGES IN THE EXTENDED...AS GENERAL UPPER AIR PATTERN REMAINS UNCHANGED. LATEST GFS IS NOW IN MUCH BETTER AGREEMENT WITH THE CANADIAN/ECMWF WITH REGARDS TO POTENTIAL SOUTHERN STREAM SYSTEM TO AFFECT THE REGION BY THE END OF THE WEEK. MODEL CONSENSUS NOW TAKES BAROCLINIC ZONE WELL TO THE SOUTH ON FRIDAY...WITH ANY CYCLOGENESIS STAYING FAR ENOUGH SOUTH TO KEEP CENTRAL ILLINOIS COLD AND DRY. CURRENT GRIDS HANDLE THE SITUATION WELL...SO NO CHANGES MADE AT THIS TIME. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ BARNES il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 226 AM EST TUE JAN 30 2007 .AVIATION... NEXT MESO VORT WILL MOVE SOUTH DOWN LAKE MICHIGAN AND SHOULD EVENTUALLY TURN SE. LATEST NAM/WRF WHICH APPEARS TO HAVE A GOOD HANDLE ON THIS SYSTEM AS LATEST RADAR AND SATELLITE ALREADY STARTING TO SHOW THIS SYSTEM TURNING TO THE SOUTHEAST. SBN AND FWA SHOULD BE WITHIN OR CLOSE TO THE SOUTHERN PERIPHERY SO HAVE TRIED TO INDICATE SOME TIMING HERE. WINDS SHOULD BACK TO THE SW OVERNIGHT...WITH SNOW DIMINISHING TO FLURRIES OR ENDING. THE SYSTEM SHOULD TEND TO WEAKEN SOME AS IT MOVE FARTHER INLAND. && .UPDATE... HAVE UPDATED FOR SMALL LOW/MESO LOW ASSOCIATED WITH IMPRESSIVE SHORT TERM SNOWFALL AMOUNTS. THIS SYSTEM HAS BEEN TRACKING SE OVER FAR SOUTHERN LOWER MICHIGAN AND NORTHERN INDIANA. SBN MEDIA REPORTED AMOUNTS SIMILAR TO WEEKEND BERRIEN COUNTY SNOWFALL RATES OF 5 INCHES IN 3 HOURS. WITH LIGHTER/DRIER SNOW AND WINDS 15 TO 25 MPH...PLENTY OF BLOWING AND DRIFTING SNOW ALREADY AND SHOULD PERSIST. EXPECT SNOWFALL TO DROP OFF AS MESO LOW MOVES DEEPER INLAND. GIVEN ANOTHER IN A SERIES OF MESO LOWS UPSTREAM OVER CENTRAL LAKE MICHIGAN...HAVE ADDED A SNOW AND BLOWING SNOW ADVISORY THROUGH EARLY TONIGHT... ALTHOUGH SHOULD BE SOMEWHAT OF A BREAK IN SNOWFALL THIS AFTERNOON BETWEEN SYSTEMS... EXCEPT FOR AREAS CLOSER TO DOWNSTREAM OF LAKE MICHIGAN. && .PREV DISCUSSION... /ISSUED 404 AM EST TUE JAN 30 2007/ SHORT TERM... TODAY AND TONIGHT. WILL BE USING THE LATEST RUC AND 00Z NAM-WRF FOR THE SHORT TERM FCST AS THEY SEEM TO HAVE A DECENT HANDLE ON THE SYNOPTIC AND MESOSCALE SITUATION. SFC ANALYSIS AT 08Z DEPICTED A CLIPPER SYSTEM ACRS THE WRN GREAT LAKES REGION. THE MAIN SFC LOW WAS LOCATED OVER WRN MICHIGAN WITH A COLD FRONT TRAILING FROM THE LOW INTO WRN INDIANA...THEN BACK INTO THE SRN PLAINS. THE MAIN SFC LOW AND COLD FRONT WILL MOVE RAPIDLY EAST THIS MORNING AWAY FROM THE REGION. KIWX RADAR WAS SHOWING A DECENT SIZE OF SNOW OUT AHEAD OF THIS FRONT OVER THE ERN TWO THIRDS OF THE FCST AREA. SOME OF THE SNOW WAS LOCALLY HEAVY IN SPOTS AS INDICATED BY THE 08Z KFWA OBSERVATION WHICH REPORTED AN INCH IN ONE HOUR. THIS SNOW WILL QUICKLY MOVE EAST EARLY THIS MORNING...AND SHOULD BE EXISTING THE ERN FCST AREA BETWEEN 5 AND 6 AM. TO THE WEST...AN UPR LVL VORT MAX WAS LOCATED OVER NRN IL. THIS FEATURE WILL SWEEP ACRS NRN INDIANA BETWEEN 12Z AND 18Z...BRINING A ROUND OF SNOW SHOWERS. TO ADD TO THE MIX...LAKE EFFECT SNOW SHOWERS WILL DEVELOP AFTER 15Z AS THE MEAN LOW LVL FLOW VEERS TO A 290 DIRECTION. MODELS INDICATE THERE COULD BE A BREAK IN THE WIDESPREAD PCPN...EXCEPT IN THE LAKE EFFECT REGIONS OF MICHIGAN AND FAR NRN INDIANA...BY THIS AFTN...BUT WILL NOT TRY TO TIME THIS ATTM. GUSTY WEST TO NORTHWEST WINDS OF 25 TO 30 MPH WILL CAUSE SOME BLOWING OF SNOW...AND HAVE ADDED THIS TO THE ZONES ACRS NRN INDIANA...SRN MICHIGAN AND FAR NORTHWEST OHIO. SNOWFALL AMOUNTS TODAY WILL RANGE FROM AROUND A HALF INCH SOUTH TO 4 INCHES IN BERRIEN AND CASS COUNTIES...WHERE A LAKE EFFECT SNOW ADVISORY WILL REMAIN IN EFFECT. FOR TONIGHT...MEAN LOW LVL FLOW WILL VEER A LITTLE MORE TO THE NORTHWEST...ABOUT 300 DEGREES. ONE LAST SURGE OF LAKE EFFECT SNOW IS EXPECTED DOWNWIND OF LAKE MICHIGAN DURING THE EVENING. THEREAFTER...INVERSION HEIGHTS WILL BEGIN TO LOWER AND DRIER AIR WILL GRADUALLY WORK INTO THE REGION FROM THE WEST TO CAUSE THE LAKE EFFECT PCPN TO DWINDLE CONSIDERABLY AFTER 06Z WEDNESDAY. WILL RAISE POPS ACRS THE MICHIGAN/FAR NRN INDIANA COUNTIES THIS EVENING IN ANTICIPATION OF THE LAST ROUND OF LAKE EFFECT PCPN. ADDITIONAL SNOWFALL AMOUNTS WILL RANGE FROM A TRACE SOUTH (FLURRIES) TO 1 TO 2 INCHES ACRS FAR NRN INDIANA/SOUTHERN MICHIGAN. SINCE POPS WILL BE RAISED TO LIKELY ACRS THE NORTH...WILL EXTEND THE LAKE EFFECT SNOW ADVISORY FOR BERRIEN AND CASS COUNTIES TO 06Z...OR 1 AM EDT. TOTAL SNOW ACCUMULATION WILL RANGE BETWEEN 4 AND 7 INCHES ACRS THE ADVISORY AREA. AS FOR TEMPS TODAY...THEY WILL BE TRICKY AS COLD ARCTIC AIR WILL CAUSE TEMPS TO TUMBLE INTO THE 10 TO 15 DEGREE RANGE BY MID MORNING ACRS THE SWRN CWFA. TEMPS WILL REMAIN SLIGHTLY WARMER DOWNWIND OF LAKE MICHIGAN. THEREAFTER...ONLY A SLIGHT DIURNAL RISE IS EXPECTED THIS AFTN. FOR TONIGHT...LOWS WILL DIP INTO THE SINGLE DIGITS ACRS MOST OF THE REGION...EXCEPT FOR LOCATIONS NEAR THE LAKE. WHERE TEMPS WILL REMAIN IN THE 10 TO 15 DEGREE RANGE. LONG TERM... WEDNESDAY THROUGH MONDAY. THE ARCTIC EXPRESS CONTINUES TO BE THE WX FOCUS THROUGH THE FORECAST PERIOD. BELOW NORMAL TEMPERATURES AND PERIODS OF SNOW WILL BE THE RULE. FORECAST MODELS HAVE BEEN RELATIVELY STABLE IN SOLUTION...SO NO REASON TO MAKE BIG CHANGES TO ONGOING FORECAST. AS POLAR VORTEX GRADUALLY SINKS SOUTH INTO SOUTHERN CANADA...SURGES OF COLDER AIR CONTINUE TO REINFORCE THE ALREADY BELOW NORMAL CONDITIONS. THE COLD AIR CONTINUES TO CAUSE LAKE EFFECT SNOW SHOWERS TO DEVELOP WHEN THE WIND DIRECTION IS FAVORABLE. WITH THE UPPER LOW IN THE AREA...A VERY UNSETTLED WEATHER PATTERN CONTINUES AS SPOKES OF ENERGY ROTATE AROUND THE UPPER LOW. THEREFORE...MOST PERIODS HAVE A MENTION OF SNOW THROUGH THE FORECAST PERIOD. COLDEST AIR OF THE SEASON IS FORECAST INTO THE AREA THIS WEEKEND. WITH FRESH SNOW COVER AND STRONG CAA...MIN TEMPS COULD APPROACH OR FALL BELOW ZERO AND MAXS WOULD STRUGGLE TO CLIMB OUT OF THE SINGLE DIGITS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...SNOW AND BLOWING SNOW ADVISORY UNTIL 1 AM EST WEDNESDAY FOR INZ004>009-016>018. MI...SNOW AND BLOWING SNOW ADVISORY UNTIL 1 AM EST WEDNESDAY FOR MIZ079>081. LAKE EFFECT SNOW WARNING UNTIL 1 AM EST WEDNESDAY FOR MIZ077-078. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 1 PM EST WEDNESDAY FOR LMZ043-046. && $$ SHORT TERM...SKIPPER AVIATION...HICKMAN LONG TERM....EDDY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1150 AM EST TUE JAN 30 2007 .UPDATE... HAVE UPDATED FOR SMALL LOW/MESO LOW ASSOCIATED WITH IMPRESSIVE SHORT TERM SNOWFALL AMOUNTS. THIS SYSTEM HAS BEEN TRACKING SE OVER FAR SOUTHERN LOWER MICHIGAN AND NORTHERN INDIANA. SBN MEDIA REPORTED AMOUNTS SIMILAR TO WEEKEND BERRIEN COUNTY SNOWFALL RATES OF 5 INCHES IN 3 HOURS. WITH LIGHTER/DRIER SNOW AND WINDS 15 TO 25 MPH...PLENTY OF BLOWING AND DRIFTING SNOW ALREADY AND SHOULD PERSIST. EXPECT SNOWFALL TO DROP OFF AS MESO LOW MOVES DEEPER INLAND. GIVEN ANOTHER IN A SERIES OF MESO LOWS UPSTREAM OVER CENTRAL LAKE MICHIGAN...HAVE ADDED A SNOW AND BLOWING SNOW ADVISORY THROUGH EARLY TONIGHT... ALTHOUGH SHOULD BE SOMEWHAT OF A BREAK IN SNOWFALL THIS AFTERNOON BETWEEN SYSTEMS... EXCEPT FOR AREAS CLOSER TO DOWNSTREAM OF LAKE MICHIGAN. && .AVIATION... AN UPR LVL VORT MAX AND ASSOCD SFC TROF WILL MOVE ACRS NRN INDIANA BETWEEN 12Z AND 18Z. LATEST KIWX RADAR INDICATED A LOW LVL MESOSCALE LAKE MICHIGAN VORTICITY MOVING INTO SOUTHWEST LOWER MICHIGAN AND FAR NORTHWEST INDIANA. THIS FEATURE WILL LIKELY DROP VSBYS TO A 1/2SM MILE FOR A COUPLE HOURS AT KSBN. THEREAFTER...ONLY SCATTERED SNOW SHOWERS AND MVFR CONDITIONS CAN BE EXPECTED AT KSBN UNTIL THIS EVENING. FOR KFWA...MVFR CIGS/VSBYS CAN BE EXPECTED THROUGH 15Z...THEN VSBYS WILL IMPROVE TO P6SM WITH ONLY A SCATTERING OF LIGHT SNOW SHOWERS IN THE VICINITY. FOR TONIGHT...ANOTHER SFC TROF AND LAST SURGE OF LAKE EFFECT SNOW IS FORECAST TO MOVE ACRS THE KSBN TAF SITE BETWEEN 00Z AND 06Z. WILL INCLUDE A PERIOD OF IFR CONDITIONS DURING THIS TIME FRAME. LAKE EFFECT SNOW SHOWERS WILL DIMINISH TO FLURRIES AND WILL PUSH NORTH INTO MICHIGAN AFTER 06Z. SFC HIGH PRESSURE IS FORECAST TO BUILD INTO THE REGION AFTER 12Z WEDNESDAY WITH VFR CONDITIONS RETURNING TO THE REGION. && .PREV DISCUSSION... /ISSUED 404 AM EST TUE JAN 30 2007/ SHORT TERM... TODAY AND TONIGHT. WILL BE USING THE LATEST RUC AND 00Z NAM-WRF FOR THE SHORT TERM FCST AS THEY SEEM TO HAVE A DECENT HANDLE ON THE SYNOPTIC AND MESOSCALE SITUATION. SFC ANALYSIS AT 08Z DEPICTED A CLIPPER SYSTEM ACRS THE WRN GREAT LAKES REGION. THE MAIN SFC LOW WAS LOCATED OVER WRN MICHIGAN WITH A COLD FRONT TRAILING FROM THE LOW INTO WRN INDIANA...THEN BACK INTO THE SRN PLAINS. THE MAIN SFC LOW AND COLD FRONT WILL MOVE RAPIDLY EAST THIS MORNING AWAY FROM THE REGION. KIWX RADAR WAS SHOWING A DECENT SIZE OF SNOW OUT AHEAD OF THIS FRONT OVER THE ERN TWO THIRDS OF THE FCST AREA. SOME OF THE SNOW WAS LOCALLY HEAVY IN SPOTS AS INDICATED BY THE 08Z KFWA OBSERVATION WHICH REPORTED AN INCH IN ONE HOUR. THIS SNOW WILL QUICKLY MOVE EAST EARLY THIS MORNING...AND SHOULD BE EXISTING THE ERN FCST AREA BETWEEN 5 AND 6 AM. TO THE WEST...AN UPR LVL VORT MAX WAS LOCATED OVER NRN IL. THIS FEATURE WILL SWEEP ACRS NRN INDIANA BETWEEN 12Z AND 18Z...BRINING A ROUND OF SNOW SHOWERS. TO ADD TO THE MIX...LAKE EFFECT SNOW SHOWERS WILL DEVELOP AFTER 15Z AS THE MEAN LOW LVL FLOW VEERS TO A 290 DIRECTION. MODELS INDICATE THERE COULD BE A BREAK IN THE WIDESPREAD PCPN...EXCEPT IN THE LAKE EFFECT REGIONS OF MICHIGAN AND FAR NRN INDIANA...BY THIS AFTN...BUT WILL NOT TRY TO TIME THIS ATTM. GUSTY WEST TO NORTHWEST WINDS OF 25 TO 30 MPH WILL CAUSE SOME BLOWING OF SNOW...AND HAVE ADDED THIS TO THE ZONES ACRS NRN INDIANA...SRN MICHIGAN AND FAR NORTHWEST OHIO. SNOWFALL AMOUNTS TODAY WILL RANGE FROM AROUND A HALF INCH SOUTH TO 4 INCHES IN BERRIEN AND CASS COUNTIES...WHERE A LAKE EFFECT SNOW ADVISORY WILL REMAIN IN EFFECT. FOR TONIGHT...MEAN LOW LVL FLOW WILL VEER A LITTLE MORE TO THE NORTHWEST...ABOUT 300 DEGREES. ONE LAST SURGE OF LAKE EFFECT SNOW IS EXPECTED DOWNWIND OF LAKE MICHIGAN DURING THE EVENING. THEREAFTER...INVERSION HEIGHTS WILL BEGIN TO LOWER AND DRIER AIR WILL GRADUALLY WORK INTO THE REGION FROM THE WEST TO CAUSE THE LAKE EFFECT PCPN TO DWINDLE CONSIDERABLY AFTER 06Z WEDNESDAY. WILL RAISE POPS ACRS THE MICHIGAN/FAR NRN INDIANA COUNTIES THIS EVENING IN ANTICIPATION OF THE LAST ROUND OF LAKE EFFECT PCPN. ADDITIONAL SNOWFALL AMOUNTS WILL RANGE FROM A TRACE SOUTH (FLURRIES) TO 1 TO 2 INCHES ACRS FAR NRN INDIANA/SOUTHERN MICHIGAN. SINCE POPS WILL BE RAISED TO LIKELY ACRS THE NORTH...WILL EXTEND THE LAKE EFFECT SNOW ADVISORY FOR BERRIEN AND CASS COUNTIES TO 06Z...OR 1 AM EDT. TOTAL SNOW ACCUMULATION WILL RANGE BETWEEN 4 AND 7 INCHES ACRS THE ADVISORY AREA. AS FOR TEMPS TODAY...THEY WILL BE TRICKY AS COLD ARCTIC AIR WILL CAUSE TEMPS TO TUMBLE INTO THE 10 TO 15 DEGREE RANGE BY MID MORNING ACRS THE SWRN CWFA. TEMPS WILL REMAIN SLIGHTLY WARMER DOWNWIND OF LAKE MICHIGAN. THEREAFTER...ONLY A SLIGHT DIURNAL RISE IS EXPECTED THIS AFTN. FOR TONIGHT...LOWS WILL DIP INTO THE SINGLE DIGITS ACRS MOST OF THE REGION...EXCEPT FOR LOCATIONS NEAR THE LAKE. WHERE TEMPS WILL REMAIN IN THE 10 TO 15 DEGREE RANGE. LONG TERM... WEDNESDAY THROUGH MONDAY. THE ARCTIC EXPRESS CONTINUES TO BE THE WX FOCUS THROUGH THE FORECAST PERIOD. BELOW NORMAL TEMPERATURES AND PERIODS OF SNOW WILL BE THE RULE. FORECAST MODELS HAVE BEEN RELATIVELY STABLE IN SOLUTION...SO NO REASON TO MAKE BIG CHANGES TO ONGOING FORECAST. AS POLAR VORTEX GRADUALLY SINKS SOUTH INTO SOUTHERN CANADA...SURGES OF COLDER AIR CONTINUE TO REINFORCE THE ALREADY BELOW NORMAL CONDITIONS. THE COLD AIR CONTINUES TO CAUSE LAKE EFFECT SNOW SHOWERS TO DEVELOP WHEN THE WIND DIRECTION IS FAVORABLE. WITH THE UPPER LOW IN THE AREA...A VERY UNSETTLED WEATHER PATTERN CONTINUES AS SPOKES OF ENERGY ROTATE AROUND THE UPPER LOW. THEREFORE...MOST PERIODS HAVE A MENTION OF SNOW THROUGH THE FORECAST PERIOD. COLDEST AIR OF THE SEASON IS FORECAST INTO THE AREA THIS WEEKEND. WITH FRESH SNOW COVER AND STRONG CAA...MIN TEMPS COULD APPROACH OR FALL BELOW ZERO AND MAXS WOULD STRUGGLE TO CLIMB OUT OF THE SINGLE DIGITS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...SNOW AND BLOWING SNOW ADVISORY UNTIL 1 AM EST WEDNESDAY FOR INZ004>009-016>018. MI...SNOW AND BLOWING SNOW ADVISORY UNTIL 1 AM EST WEDNESDAY FOR MIZ079>081. LAKE EFFECT SNOW WARNING UNTIL 1 AM EST WEDNESDAY FOR MIZ077-078. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 1 PM EST WEDNESDAY FOR LMZ043-046. && $$ SHORT TERM...SKIPPER AVIATION...HICKMAN LONG TERM....EDDY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 635 AM EST TUE JAN 30 2007 .AVIATION... AN UPR LVL VORT MAX AND ASSOCD SFC TROF WILL MOVE ACRS NRN INDIANA BETWEEN 12Z AND 18Z. LATEST KIWX RADAR INDICATED A LOW LVL MESOSCALE LAKE MICHIGAN VORTICITY MOVING INTO SOUTHWEST LOWER MICHIGAN AND FAR NORTHWEST INDIANA. THIS FEATURE WILL LIKELY DROP VSBYS TO A 1/2SM MILE FOR A COUPLE HOURS AT KSBN. THEREAFTER...ONLY SCATTERED SNOW SHOWERS AND MVFR CONDITIONS CAN BE EXPECTED AT KSBN UNTIL THIS EVENING. FOR KFWA...MVFR CIGS/VSBYS CAN BE EXPECTED THROUGH 15Z...THEN VSBYS WILL IMPROVE TO P6SM WITH ONLY A SCATTERING OF LIGHT SNOW SHOWERS IN THE VICINITY. FOR TONIGHT...ANOTHER SFC TROF AND LAST SURGE OF LAKE EFFECT SNOW IS FORECAST TO MOVE ACRS THE KSBN TAF SITE BETWEEN 00Z AND 06Z. WILL INCLUDE A PERIOD OF IFR CONDITIONS DURING THIS TIME FRAME. LAKE EFFECT SNOW SHOWERS WILL DIMINISH TO FLURRIES AND WILL PUSH NORTH INTO MICHIGAN AFTER 06Z. SFC HIGH PRESSURE IS FORECAST TO BUILD INTO THE REGION AFTER 12Z WEDNESDAY WITH VFR CONDITIONS RETURNING TO THE REGION. && .PREV DISCUSSION... /ISSUED 404 AM EST TUE JAN 30 2007/ SHORT TERM... TODAY AND TONIGHT. WILL BE USING THE LATEST RUC AND 00Z NAM-WRF FOR THE SHORT TERM FCST AS THEY SEEM TO HAVE A DECENT HANDLE ON THE SYNOPTIC AND MESOSCALE SITUATION. SFC ANALYSIS AT 08Z DEPICTED A CLIPPER SYSTEM ACRS THE WRN GREAT LAKES REGION. THE MAIN SFC LOW WAS LOCATED OVER WRN MICHIGAN WITH A COLD FRONT TRAILING FROM THE LOW INTO WRN INDIANA...THEN BACK INTO THE SRN PLAINS. THE MAIN SFC LOW AND COLD FRONT WILL MOVE RAPIDLY EAST THIS MORNING AWAY FROM THE REGION. KIWX RADAR WAS SHOWING A DECENT SIZE OF SNOW OUT AHEAD OF THIS FRONT OVER THE ERN TWO THIRDS OF THE FCST AREA. SOME OF THE SNOW WAS LOCALLY HEAVY IN SPOTS AS INDICATED BY THE 08Z KFWA OBSERVATION WHICH REPORTED AN INCH IN ONE HOUR. THIS SNOW WILL QUICKLY MOVE EAST EARLY THIS MORNING...AND SHOULD BE EXISTING THE ERN FCST AREA BETWEEN 5 AND 6 AM. TO THE WEST...AN UPR LVL VORT MAX WAS LOCATED OVER NRN IL. THIS FEATURE WILL SWEEP ACRS NRN INDIANA BETWEEN 12Z AND 18Z...BRINING A ROUND OF SNOW SHOWERS. TO ADD TO THE MIX...LAKE EFFECT SNOW SHOWERS WILL DEVELOP AFTER 15Z AS THE MEAN LOW LVL FLOW VEERS TO A 290 DIRECTION. MODELS INDICATE THERE COULD BE A BREAK IN THE WIDESPREAD PCPN...EXCEPT IN THE LAKE EFFECT REGIONS OF MICHIGAN AND FAR NRN INDIANA...BY THIS AFTN...BUT WILL NOT TRY TO TIME THIS ATTM. GUSTY WEST TO NORTHWEST WINDS OF 25 TO 30 MPH WILL CAUSE SOME BLOWING OF SNOW...AND HAVE ADDED THIS TO THE ZONES ACRS NRN INDIANA...SRN MICHIGAN AND FAR NORTHWEST OHIO. SNOWFALL AMOUNTS TODAY WILL RANGE FROM AROUND A HALF INCH SOUTH TO 4 INCHES IN BERRIEN AND CASS COUNTIES...WHERE A LAKE EFFECT SNOW ADVISORY WILL REMAIN IN EFFECT. FOR TONIGHT...MEAN LOW LVL FLOW WILL VEER A LITTLE MORE TO THE NORTHWEST...ABOUT 300 DEGREES. ONE LAST SURGE OF LAKE EFFECT SNOW IS EXPECTED DOWNWIND OF LAKE MICHIGAN DURING THE EVENING. THEREAFTER...INVERSION HEIGHTS WILL BEGIN TO LOWER AND DRIER AIR WILL GRADUALLY WORK INTO THE REGION FROM THE WEST TO CAUSE THE LAKE EFFECT PCPN TO DWINDLE CONSIDERABLY AFTER 06Z WEDNESDAY. WILL RAISE POPS ACRS THE MICHIGAN/FAR NRN INDIANA COUNTIES THIS EVENING IN ANTICIPATION OF THE LAST ROUND OF LAKE EFFECT PCPN. ADDITIONAL SNOWFALL AMOUNTS WILL RANGE FROM A TRACE SOUTH (FLURRIES) TO 1 TO 2 INCHES ACRS FAR NRN INDIANA/SOUTHERN MICHIGAN. SINCE POPS WILL BE RAISED TO LIKELY ACRS THE NORTH...WILL EXTEND THE LAKE EFFECT SNOW ADVISORY FOR BERRIEN AND CASS COUNTIES TO 06Z...OR 1 AM EDT. TOTAL SNOW ACCUMULATION WILL RANGE BETWEEN 4 AND 7 INCHES ACRS THE ADVISORY AREA. AS FOR TEMPS TODAY...THEY WILL BE TRICKY AS COLD ARCTIC AIR WILL CAUSE TEMPS TO TUMBLE INTO THE 10 TO 15 DEGREE RANGE BY MID MORNING ACRS THE SWRN CWFA. TEMPS WILL REMAIN SLIGHTLY WARMER DOWNWIND OF LAKE MICHIGAN. THEREAFTER...ONLY A SLIGHT DIURNAL RISE IS EXPECTED THIS AFTN. FOR TONIGHT...LOWS WILL DIP INTO THE SINGLE DIGITS ACRS MOST OF THE REGION...EXCEPT FOR LOCATIONS NEAR THE LAKE. WHERE TEMPS WILL REMAIN IN THE 10 TO 15 DEGREE RANGE. LONG TERM... WEDNESDAY THROUGH MONDAY. THE ARCTIC EXPRESS CONTINUES TO BE THE WX FOCUS THROUGH THE FORECAST PERIOD. BELOW NORMAL TEMPERATURES AND PERIODS OF SNOW WILL BE THE RULE. FORECAST MODELS HAVE BEEN RELATIVELY STABLE IN SOLUTION...SO NO REASON TO MAKE BIG CHANGES TO ONGOING FORECAST. AS POLAR VORTEX GRADUALLY SINKS SOUTH INTO SOUTHERN CANADA...SURGES OF COLDER AIR CONTINUE TO REINFORCE THE ALREADY BELOW NORMAL CONDITIONS. THE COLD AIR CONTINUES TO CAUSE LAKE EFFECT SNOW SHOWERS TO DEVELOP WHEN THE WIND DIRECTION IS FAVORABLE. WITH THE UPPER LOW IN THE AREA...A VERY UNSETTLED WEATHER PATTERN CONTINUES AS SPOKES OF ENERGY ROTATE AROUND THE UPPER LOW. THEREFORE...MOST PERIODS HAVE A MENTION OF SNOW THROUGH THE FORECAST PERIOD. COLDEST AIR OF THE SEASON IS FORECAST INTO THE AREA THIS WEEKEND. WITH FRESH SNOW COVER AND STRONG CAA...MIN TEMPS COULD APPROACH OR FALL BELOW ZERO AND MAXS WOULD STRUGGLE TO CLIMB OUT OF THE SINGLE DIGITS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...LAKE EFFECT SNOW ADVISORY UNTIL 1 AM EST WEDNESDAY FOR MIZ077- 078. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 1 PM EST WEDNESDAY FOR LMZ043-046. && $$ SHORT TERM/AVIATION...HICKMAN LONG TERM....EDDY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 404 AM EST TUE JAN 30 2007 .SHORT TERM... TODAY AND TONIGHT. WILL BE USING THE LATEST RUC AND 00Z NAM-WRF FOR THE SHORT TERM FCST AS THEY SEEM TO HAVE A DECENT HANDLE ON THE SYNOPTIC AND MESOSCALE SITUATION. SFC ANALYSIS AT 08Z DEPICTED A CLIPPER SYSTEM ACRS THE WRN GREAT LAKES REGION. THE MAIN SFC LOW WAS LOCATED OVER WRN MICHIGAN WITH A COLD FRONT TRAILING FROM THE LOW INTO WRN INDIANA...THEN BACK INTO THE SRN PLAINS. THE MAIN SFC LOW AND COLD FRONT WILL MOVE RAPIDLY EAST THIS MORNING AWAY FROM THE REGION. KIWX RADAR WAS SHOWING A DECENT SIZE OF SNOW OUT AHEAD OF THIS FRONT OVER THE ERN TWO THIRDS OF THE FCST AREA. SOME OF THE SNOW WAS LOCALLY HEAVY IN SPOTS AS INDICATED BY THE 08Z KFWA OBSERVATION WHICH REPORTED AN INCH IN ONE HOUR. THIS SNOW WILL QUICKLY MOVE EAST EARLY THIS MORNING...AND SHOULD BE EXISTING THE ERN FCST AREA BETWEEN 5 AND 6 AM. TO THE WEST...AN UPR LVL VORT MAX WAS LOCATED OVER NRN IL. THIS FEATURE WILL SWEEP ACRS NRN INDIANA BETWEEN 12Z AND 18Z...BRINING A ROUND OF SNOW SHOWERS. TO ADD TO THE MIX...LAKE EFFECT SNOW SHOWERS WILL DEVELOP AFTER 15Z AS THE MEAN LOW LVL FLOW VEERS TO A 290 DIRECTION. MODELS INDICATE THERE COULD BE A BREAK IN THE WIDESPREAD PCPN...EXCEPT IN THE LAKE EFFECT REGIONS OF MICHIGAN AND FAR NRN INDIANA...BY THIS AFTN...BUT WILL NOT TRY TO TIME THIS ATTM. GUSTY WEST TO NORTHWEST WINDS OF 25 TO 30 MPH WILL CAUSE SOME BLOWING OF SNOW...AND HAVE ADDED THIS TO THE ZONES ACRS NRN INDIANA...SRN MICHIGAN AND FAR NORTHWEST OHIO. SNOWFALL AMOUNTS TODAY WILL RANGE FROM AROUND A HALF INCH SOUTH TO 4 INCHES IN BERRIEN AND CASS COUNTIES...WHERE A LAKE EFFECT SNOW ADVISORY WILL REMAIN IN EFFECT. FOR TONIGHT...MEAN LOW LVL FLOW WILL VEER A LITTLE MORE TO THE NORTHWEST...ABOUT 300 DEGREES. ONE LAST SURGE OF LAKE EFFECT SNOW IS EXPECTED DOWNWIND OF LAKE MICHIGAN DURING THE EVENING. THEREAFTER...INVERSION HEIGHTS WILL BEGIN TO LOWER AND DRIER AIR WILL GRADUALLY WORK INTO THE REGION FROM THE WEST TO CAUSE THE LAKE EFFECT PCPN TO DWINDLE CONSIDERABLY AFTER 06Z WEDNESDAY. WILL RAISE POPS ACRS THE MICHIGAN/FAR NRN INDIANA COUNTIES THIS EVENING IN ANTICIPATION OF THE LAST ROUND OF LAKE EFFECT PCPN. ADDITIONAL SNOWFALL AMOUNTS WILL RANGE FROM A TRACE SOUTH (FLURRIES) TO 1 TO 2 INCHES ACRS FAR NRN INDIANA/SOUTHERN MICHIGAN. SINCE POPS WILL BE RAISED TO LIKELY ACRS THE NORTH...WILL EXTEND THE LAKE EFFECT SNOW ADVISORY FOR BERRIEN AND CASS COUNTIES TO 06Z...OR 1 AM EDT. TOTAL SNOW ACCUMULATION WILL RANGE BETWEEN 4 AND 7 INCHES ACRS THE ADVISORY AREA. AS FOR TEMPS TODAY...THEY WILL BE TRICKY AS COLD ARCTIC AIR WILL CAUSE TEMPS TO TUMBLE INTO THE 10 TO 15 DEGREE RANGE BY MID MORNING ACRS THE SWRN CWFA. TEMPS WILL REMAIN SLIGHTLY WARMER DOWNWIND OF LAKE MICHIGAN. THEREAFTER...ONLY A SLIGHT DIURNAL RISE IS EXPECTED THIS AFTN. FOR TONIGHT...LOWS WILL DIP INTO THE SINGLE DIGITS ACRS MOST OF THE REGION...EXCEPT FOR LOCATIONS NEAR THE LAKE. WHERE TEMPS WILL REMAIN IN THE 10 TO 15 DEGREE RANGE. && .LONG TERM... WEDNESDAY THROUGH MONDAY. THE ARCTIC EXPRESS CONTINUES TO BE THE WX FOCUS THROUGH THE FORECAST PERIOD. BELOW NORMAL TEMPERATURES AND PERIODS OF SNOW WILL BE THE RULE. FORECAST MODELS HAVE BEEN RELATIVELY STABLE IN SOLUTION...SO NO REASON TO MAKE BIG CHANGES TO ONGOING FORECAST. AS POLAR VORTEX GRADUALLY SINKS SOUTH INTO SOUTHERN CANADA...SURGES OF COLDER AIR CONTINUE TO REINFORCE THE ALREADY BELOW NORMAL CONDITIONS. THE COLD AIR CONTINUES TO CAUSE LAKE EFFECT SNOW SHOWERS TO DEVELOP WHEN THE WIND DIRECTION IS FAVORABLE. WITH THE UPPER LOW IN THE AREA...A VERY UNSETTLED WEATHER PATTERN CONTINUES AS SPOKES OF ENERGY ROTATE AROUND THE UPPER LOW. THEREFORE...MOST PERIODS HAVE A MENTION OF SNOW THROUGH THE FORECAST PERIOD. COLDEST AIR OF THE SEASON IS FORECAST INTO THE AREA THIS WEEKEND. WITH FRESH SNOW COVER AND STRONG CAA...MIN TEMPS COULD APPROACH OR FALL BELOW ZERO AND MAXS WOULD STRUGGLE TO CLIMB OUT OF THE SINGLE DIGITS. && .PREV DISCUSSION... /ISSUED 1229 AM EST TUE JAN 30 2007/ AVIATION... A FAST MOVING CLIPPER SYSTEM WILL PUSH ACRS THE WESTERN GREAT LAKES THROUGH 12Z...THEN IT WILL MOVE EAST INTO THE ERN GREAT LAKES BY 18Z. SVRL UPR LVL WX DISTURBANCES ALOFT WILL ACCOMPANY THIS SYSTEM OVERNIGHT. THE COMBINATION OF UPR LVL LIFT AND LOW LVL CONVERGENCE AHEAD OF A COLD FRONT WILL BRING WIDESPREAD SNOW TO NRN INDIANA ANS SUBSEQUENT TAF SITES THROUGH AT LEAST 15Z. THEREAFTER...COLD AIR FLOWING OVER THE RELATIVELY WARM WATERS OF LAKE MICHIGAN WILL GENERATE LAKE EFFECT SNOW SHOWERS...WHICH SHOULD MAINLY AFFECT THE KSBN TAF SITE. MVFR/IFR CONDITIONS CAN BE EXPECTED THROUGH AT LEAST 15Z...WITH MVFR AND POSSIBLE IFR CONDITIONS BEYOND 15Z WITH LAKE EFFECT SNOW SHOWERS. WIND GUSTS AROUND 25 KNOTS CAN BE EXPECTED IN THE WAKE OF THE COLD FRONT...WHICH WILL CAUSE SOME BLOWING SNOW TO OCCUR AT KSBN BEYOND 12Z. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...LAKE EFFECT SNOW ADVISORY UNTIL 1 AM EST WEDNESDAY FOR MIZ077- 078. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 1 PM EST WEDNESDAY FOR LMZ043-046. && $$ SHORT TERM/AVIATION...HICKMAN LONG TERM....EDDY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 1220 PM EST TUE JAN 30 2007 .AVIATION (18Z TAFS)... GUSTY NORTHWEST WINDS TO 22KTS ARE EXPECTED IN THE WAKE OF A COLD FRONT WHICH HAS MOVED EAST OF THE TAF SITES. THESE GUSTY WINDS WILL DIMINISH AROUND 00Z. SCT TO BKN CU WILL BE POSSIBLE ACROSS SDF AND LEX THIS AFTERNOON AS AN UPPER TROUGH MOVES THROUGH THE LOWER OHIO VALLEY. CLEAR SKIES AND VFR VSBYS EXPECTED AFTER 02Z. --JA .SHORT TERM (THIS AFTERNOON)... AT 16Z A COLD FRONT WAS LOCATED EAST OF A LINE FROM WINCHESTER IN CENTRAL KY TO GLASGOW. TEMPERATURES HAD DROPPED 5 TO 10 DEGREES JUST AFTER THE FRONTAL PASSAGE AND LOOKING UP STREAM READINGS WERE IN THE TEENS. JUST LIKE SUNDAY... DEW POINTS HAVE DROPPED INTO THE SINGLE DIGITS ACROSS THE NORTHERN PORTION OF THE CWFA. WILL CONTINUE TO MENTION ISOLATED TO LIGHT SNOW SHOWERS THIS AFTERNOON AS CU FIELD DEVELOPS BEHIND THE FRONT AND WITH STEEPENING LAPSE RATES. TEMPERATURES WILL CONTINUE THEIR SLOW DOWNWARD TREND EVEN WITH SOME SUNSHINE. UPDATED FORECAST OUT BY 1115. --JA PREVIOUS DISCUSSION BELOW. CLIPPER SHORT WAVE MOVING ESE THROUGH IOWA INTO IL/IN ATTM...WITH ASSOC SFC TROF/FRONT STRETCHING FROM NEAR IND TO PAH AS OF 6Z. MOISTURE POOLING ALONG THE FRONT...WITH DEWPOINTS RISING INTO THE MID 20S. SCT SHSN HAVE DEVELOPED ALONG/AHEAD OF THE SFC FRONT...WITH A FEW MOVING INTO THE LMK CWA AND AS FAR S AS NEAR LEITCHFIELD. RECENT ACARS DATA AT KSDF SHOW VERY STEEP LAPSE RATES TO 700MB... HELPING PROMOTE THIS PRECIP. EXPECT ISLTD-SCT SHSN TO REMAIN POSSIBLE THROUGH THE MORNING HOURS...WITH HIGHEST CHCS OVER THE N 1/2 OF THE CWA...DECREASING SOUTHWARD. ANY SNOW AMTS SHOULD BE MINOR AT BEST THOUGH SOME OF THE SHSN HAVE BEEN INTENSE OVER IL/IN/OH BASED ON RADAR REFLECTIVITIES NEAR 35DBZ OR HIGHER...SO IF SOME OF THESE WERE TO AFFECT OUR CWA THERE COULD BE LOCALIZED ACCUMS OF A COUPLE TENTHS OF AN INCH IN A SHORT PERIOD OF TIME. WILL CONTINUE TO MONITOR AS WE GET CLOSER TO THE MORNING DRIVE. BASED ON NAM/RUC...SFC FRONT WILL PASS THROUGH WRN COUNTIES AROUND 10-12Z...INTO ERN/SRN COUNTIES 12-14Z TIMEFRAME. THIS WILL BRING A ROUND OF GUSTY W/NW WINDS TODAY. BUFKIT DIAGNOSTICS INDICATE GUSTS TO 20-25KTS POSSIBLE AND THIS SEEMS REASONABLE BASED ON UPSTREAM OBSERVATIONS. THIS WILL ALSO BRING STEADY OR FALLING TEMPS (EXCEPT PERHAPS THE FAR SE COUNTIES). HAVE FOLLOWED A RUC/NAM BLEND FOR TEMPS TODAY INTO TONIGHT. CHANCES FOR SHSN WILL CONTINUE INTO THE AFTN WITH STEEP LAPSE RATES...THOUGH FEEL THAT OVERALL THREAT WILL BE LOWER THAN IN THE MORNING DUE TO SIGNIFICANTLY DRIER AIR ADVECTING INTO THE LOWER OHIO VALLEY. DEWPOINTS WILL LIKELY FALL INTO THE SINGLE DIGITS THIS AFTN. WILL WORD AFTERNOON POPS AS CHANCE VERSUS MORNING COVERAGE WORDING. GUSTY WINDS WILL LIGHTEN AFTER SUNSET...THOUGH BEFORE THAT OCCURS WIND CHILL VALUES THIS AFTN INTO THE EARLY EVENING WILL LIKELY DROP INTO THE SINGLE DIGITS WITH A FEW NEAR-ZERO VALUES POSSIBLE. HAVE ALLOWED SKIES TO CLEAR OVERNIGHT...THOUGH DID NOT GO WITH COMPLETE CLEARING SINCE NAM AND TO A LESSER EXTENT GFS SUGGEST AN AREA OF 3-5KFT CLOUDS SWEEPING ACROSS THE CWA BETWEEN 6-9Z/WED (OVERNIGHT). CS && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 1105 AM EST TUE JAN 30 2007 .SHORT TERM (THIS AFTERNOON)... AT 16Z A COLD FRONT WAS LOCATED EAST OF A LINE FROM WINCHESTER IN CENTRAL KY TO GLASGOW. TEMPERATURES HAD DROPPED 5 TO 10 DEGREES JUST AFTER THE FRONTAL PASSAGE AND LOOKING UP STREAM READINGS WERE IN THE TEENS. JUST LIKE SUNDAY... DEW POINTS HAVE DROPPED INTO THE SINGLE DIGITS ACROSS THE NORTHERN PORTION OF THE CWFA. WILL CONTINUE TO MENTION ISOLATED TO LIGHT SNOW SHOWERS THIS AFTERNOON AS CU FIELD DEVELOPS BEHIND THE FRONT AND WITH STEEPENING LAPSE RATES. TEMPERATURES WILL CONTINUE THEIR SLOW DOWNWARD TREND EVEN WITH SOME SUNSHINE. UPDATED FORECAST OUT BY 1115. --JA PREVIOUS DISCUSSION BELOW. CLIPPER SHORT WAVE MOVING ESE THROUGH IOWA INTO IL/IN ATTM...WITH ASSOC SFC TROF/FRONT STRETCHING FROM NEAR IND TO PAH AS OF 6Z. MOISTURE POOLING ALONG THE FRONT...WITH DEWPOINTS RISING INTO THE MID 20S. SCT SHSN HAVE DEVELOPED ALONG/AHEAD OF THE SFC FRONT...WITH A FEW MOVING INTO THE LMK CWA AND AS FAR S AS NEAR LEITCHFIELD. RECENT ACARS DATA AT KSDF SHOW VERY STEEP LAPSE RATES TO 700MB... HELPING PROMOTE THIS PRECIP. EXPECT ISLTD-SCT SHSN TO REMAIN POSSIBLE THROUGH THE MORNING HOURS...WITH HIGHEST CHCS OVER THE N 1/2 OF THE CWA...DECREASING SOUTHWARD. ANY SNOW AMTS SHOULD BE MINOR AT BEST THOUGH SOME OF THE SHSN HAVE BEEN INTENSE OVER IL/IN/OH BASED ON RADAR REFLECTIVITIES NEAR 35DBZ OR HIGHER...SO IF SOME OF THESE WERE TO AFFECT OUR CWA THERE COULD BE LOCALIZED ACCUMS OF A COUPLE TENTHS OF AN INCH IN A SHORT PERIOD OF TIME. WILL CONTINUE TO MONITOR AS WE GET CLOSER TO THE MORNING DRIVE. BASED ON NAM/RUC...SFC FRONT WILL PASS THROUGH WRN COUNTIES AROUND 10-12Z...INTO ERN/SRN COUNTIES 12-14Z TIMEFRAME. THIS WILL BRING A ROUND OF GUSTY W/NW WINDS TODAY. BUFKIT DIAGNOSTICS INDICATE GUSTS TO 20-25KTS POSSIBLE AND THIS SEEMS REASONABLE BASED ON UPSTREAM OBSERVATIONS. THIS WILL ALSO BRING STEADY OR FALLING TEMPS (EXCEPT PERHAPS THE FAR SE COUNTIES). HAVE FOLLOWED A RUC/NAM BLEND FOR TEMPS TODAY INTO TONIGHT. CHANCES FOR SHSN WILL CONTINUE INTO THE AFTN WITH STEEP LAPSE RATES...THOUGH FEEL THAT OVERALL THREAT WILL BE LOWER THAN IN THE MORNING DUE TO SIGNIFICANTLY DRIER AIR ADVECTING INTO THE LOWER OHIO VALLEY. DEWPOINTS WILL LIKELY FALL INTO THE SINGLE DIGITS THIS AFTN. WILL WORD AFTERNOON POPS AS CHANCE VERSUS MORNING COVERAGE WORDING. GUSTY WINDS WILL LIGHTEN AFTER SUNSET...THOUGH BEFORE THAT OCCURS WIND CHILL VALUES THIS AFTN INTO THE EARLY EVENING WILL LIKELY DROP INTO THE SINGLE DIGITS WITH A FEW NEAR-ZERO VALUES POSSIBLE. HAVE ALLOWED SKIES TO CLEAR OVERNIGHT...THOUGH DID NOT GO WITH COMPLETE CLEARING SINCE NAM AND TO A LESSER EXTENT GFS SUGGEST AN AREA OF 3-5KFT CLOUDS SWEEPING ACROSS THE CWA BETWEEN 6-9Z/WED (OVERNIGHT). CS .AVIATION (12Z TAFS)... COLD FRONT NOW ROLLING THROUGH THE LMK CWA AS OF 11Z...WITH WINDS AT HNB SOLIDLY NW WHILE DIRECTIONS AT SDF/FTK SWITCHING SOON. WITH FROPA...WE EXPECT WNW WINDS WILL INCREASE AND BECOME GUSTY. GUSTS TO 20-25KTS ARE LIKELY THROUGH AT LEAST MID-AFTERNOON TODAY. SHSN ARE WIDELY SCATTERED AT THIS POINT AND CIGS ARE VFR-MVFR UPSTREAM OVER SRN IL AND SW IN. LATEST NAM SHOWS CIGS DROPPING TO AROUND 3000 FEET THIS MORNING AT SDF/LEX...THEN RISING TO NEAR 5KFT WITH SKIES ACTUALLY GOING SCT (EVEN FEW OVER SRN KY). -SHSN THREAT FOR THE TAF SITES SEEMS MINIMAL...WILL NOT MENTION IN PREVAILING GROUPS AND HANDLE ANY -SHSN WITH TEMPO GROUPS IF NECESSARY. GFS/NAM HAVE BEEN CONSISTENT IN BRINGING AN AREA OF LOWER CIGS (~2KFT) TONIGHT BETWEEN 0Z-6Z...AND WILL ACCOUNT FOR THIS. WINDS WILL SUBSIDE CONSIDERABLY AFTER 3Z AS SFC HIGH PRES SLIDES INTO THE REGION. CS && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 605 AM EST TUE JAN 30 2007 .AVIATION (12Z TAFS)... COLD FRONT NOW ROLLING THROUGH THE LMK CWA AS OF 11Z...WITH WINDS AT HNB SOLIDLY NW WHILE DIRECTIONS AT SDF/FTK SWITCHING SOON. WITH FROPA...WE EXPECT WNW WINDS WILL INCREASE AND BECOME GUSTY. GUSTS TO 20-25KTS ARE LIKELY THROUGH AT LEAST MID-AFTERNOON TODAY. SHSN ARE WIDELY SCATTERED AT THIS POINT AND CIGS ARE VFR-MVFR UPSTREAM OVER SRN IL AND SW IN. LATEST NAM SHOWS CIGS DROPPING TO AROUND 3000 FEET THIS MORNING AT SDF/LEX...THEN RISING TO NEAR 5KFT WITH SKIES ACTUALLY GOING SCT (EVEN FEW OVER SRN KY). -SHSN THREAT FOR THE TAF SITES SEEMS MINIMAL...WILL NOT MENTION IN PREVAILING GROUPS AND HANDLE ANY -SHSN WITH TEMPO GROUPS IF NECESSARY. GFS/NAM HAVE BEEN CONSISTENT IN BRINGING AN AREA OF LOWER CIGS (~2KFT) TONIGHT BETWEEN 0Z-6Z...AND WILL ACCOUNT FOR THIS. WINDS WILL SUBSIDE CONSIDERABLY AFTER 3Z AS SFC HIGH PRES SLIDES INTO THE REGION. CS && .SHORT TERM (TODAY-TONIGHT)... CLIPPER SHORT WAVE MOVING ESE THROUGH IOWA INTO IL/IN ATTM...WITH ASSOC SFC TROF/FRONT STRETCHING FROM NEAR IND TO PAH AS OF 6Z. MOISTURE POOLING ALONG THE FRONT...WITH DEWPOINTS RISING INTO THE MID 20S. SCT SHSN HAVE DEVELOPED ALONG/AHEAD OF THE SFC FRONT...WITH A FEW MOVING INTO THE LMK CWA AND AS FAR S AS NEAR LEITCHFIELD. RECENT ACARS DATA AT KSDF SHOW VERY STEEP LAPSE RATES TO 700MB... HELPING PROMOTE THIS PRECIP. EXPECT ISLTD-SCT SHSN TO REMAIN POSSIBLE THROUGH THE MORNING HOURS...WITH HIGHEST CHCS OVER THE N 1/2 OF THE CWA...DECREASING SOUTHWARD. ANY SNOW AMTS SHOULD BE MINOR AT BEST THOUGH SOME OF THE SHSN HAVE BEEN INTENSE OVER IL/IN/OH BASED ON RADAR REFLECTIVITIES NEAR 35DBZ OR HIGHER...SO IF SOME OF THESE WERE TO AFFECT OUR CWA THERE COULD BE LOCALIZED ACCUMS OF A COUPLE TENTHS OF AN INCH IN A SHORT PERIOD OF TIME. WILL CONTINUE TO MONITOR AS WE GET CLOSER TO THE MORNING DRIVE. BASED ON NAM/RUC...SFC FRONT WILL PASS THROUGH WRN COUNTIES AROUND 10-12Z...INTO ERN/SRN COUNTIES 12-14Z TIMEFRAME. THIS WILL BRING A ROUND OF GUSTY W/NW WINDS TODAY. BUFKIT DIAGNOSTICS INDICATE GUSTS TO 20-25KTS POSSIBLE AND THIS SEEMS REASONABLE BASED ON UPSTREAM OBSERVATIONS. THIS WILL ALSO BRING STEADY OR FALLING TEMPS (EXCEPT PERHAPS THE FAR SE COUNTIES). HAVE FOLLOWED A RUC/NAM BLEND FOR TEMPS TODAY INTO TONIGHT. CHANCES FOR SHSN WILL CONTINUE INTO THE AFTN WITH STEEP LAPSE RATES...THOUGH FEEL THAT OVERALL THREAT WILL BE LOWER THAN IN THE MORNING DUE TO SIGNIFICANTLY DRIER AIR ADVECTING INTO THE LOWER OHIO VALLEY. DEWPOINTS WILL LIKELY FALL INTO THE SINGLE DIGITS THIS AFTN. WILL WORD AFTERNOON POPS AS CHANCE VERSUS MORNING COVERAGE WORDING. GUSTY WINDS WILL LIGHTEN AFTER SUNSET...THOUGH BEFORE THAT OCCURS WIND CHILL VALUES THIS AFTN INTO THE EARLY EVENING WILL LIKELY DROP INTO THE SINGLE DIGITS WITH A FEW NEAR-ZERO VALUES POSSIBLE. HAVE ALLOWED SKIES TO CLEAR OVERNIGHT...THOUGH DID NOT GO WITH COMPLETE CLEARING SINCE NAM AND TO A LESSER EXTENT GFS SUGGEST AN AREA OF 3-5KFT CLOUDS SWEEPING ACROSS THE CWA BETWEEN 6-9Z/WED (OVERNIGHT). CS .LONG TERM (WEDNESDAY-MONDAY)... ...ACTIVE WEATHER PERIOD WITH POTENTIAL FOR ACCUMULATING SNOWS LATE WED THROUGH THURSDAY NIGHT... WEDNESDAY THROUGH FRIDAY NIGHT... FAIRLY ACTIVE AND CHALLENGING FORECAST PERIOD APPEARS TO BE IN STORE FOR THIS PART OF THE FORECAST PERIOD. LATE EVENING MODELS CONTINUE TO BE IN GENERAL AGREEMENT WITH SOUTHWESTERN U.S. UPPER LEVEL WAVE EJECTING EASTWARD DURING THE PERIOD. ALL THE MODELS INDUCE SFC CYCLOGENESIS ACROSS THE DEEP SOUTH AND BRING A SFC LOW EASTWARD ACROSS THE NORTHERN GULF STATES. THE PAST FEW RUNS OF THE MODELS HAVE BEEN TRENDING NORTHWARD WITH THE TRACK OF THE SFC LOW ACROSS THE SOUTHEAST U.S. WE STILL HAVE TWO CAMPS OF TRACKS TONIGHT...WITH THE CANADIAN GLOBAL AND NAM-WRF BEING THE FARTHEST NORTH WITH THE LOW COMING ACROSS THE FA...WHILE THE UKMET AND EURO ARE FURTHER SOUTH. THE 00Z OP GFS IS BETWEEN THESE TWO CAMPS AND OFFERS A PRETTY GOOD COMPROMISE. USING A CONSENSUS OF THE MODEL DATA...WEDNESDAY WILL GENERALLY BE A DRY DAY WITH MID-HIGH LEVEL CLOUDS INCREASING FROM WEST TO EAST. ISENTROPIC UPGLIDE WILL INCREASE WEDNESDAY EVENING AS SFC LOW BEGINS ITS TREK TOWARDS THE NORTHEAST. ANTECEDENT DRY AIRMASS WILL TAKE SOME TIME TO MOISTEN UP WEDNESDAY NIGHT SO PRECIPITATION MAY NOT START UNTIL LATE WEDNESDAY NIGHT. NONETHELESS...IT DOES APPEAR PRECIPITATION WILL BE LIKELY AND THUS HAVE INCREASED POPS TO LIKELY FOR THIS PERIOD. MODEL PROFILES FROM THE GFS SUGGEST ALL SNOW AS THE PRECIPITATION TYPE FOR WEDNESDAY NIGHT. MAIN BULK OF PRECIPITATION WILL FALL ON THURSDAY AS ISENTROPIC LIFT AND FRONTOGENETICAL FORCING WILL BE MAXIMIZED OVER KENTUCKY. BANDED PRECIPITATION WILL LIKELY LIFT NORTHWARD THROUGH THE DAY AND BE ORIENTED ALONG THE OHIO RIVER BY EVENING. HAVE GONE WITH LIKELY POPS HERE BUT PRECIPITATION TYPE WILL BE CHALLENGING. IN THE PAST SEVERAL EVENTS...WE HAVE SEEN STORMS SYSTEMS OUT IN THE LONG RANGE BEING FORECAST TO GO SOUTH...ONLY TO SEE A NORTHWARD TRACK VERIFY AS THE EVENT CAME CLOSER/UNFOLDED. IN ADDITION...THE NUMERICAL MODELS HAVE HAD A TOUGH TIME ESTIMATING THE AMOUNT OF WARM AIR ADVECTING IN ALOFT...WHICH HAS RESULTED IN MORE LIQUID PRECIPITATION OCCURRING. TONIGHT...WE ARE IN THE SAME DILEMMA. BASED ON ALL THE AVAILABLE DATA...AND NOT COMPLETELY THROWING OUT THE NAM-WRF...AM INCLINED TO LEAVE A MIX OF RAIN/SLEET/SNOW IN ACROSS THE SOUTHERN FA SOUTH OF A LINE FROM NEAR HARTFORD TO JUST SOUTH OF RICHMOND. NORTH OF THAT LINE...FEEL THAT DOMINANT PRECIPITATION TYPE WILL BE SNOW. AS SFC LOW HEADS EAST THU NIGHT...SHOULD SEE ALL AREAS GO TO SNOW. ACCUMULATIONS OF SNOW APPEAR LIKELY AT THIS TIME WITH TWO TO FOUR INCHES ACROSS THE NORTHERN HALF OF THE FA WITH ONE TO TWO ACROSS SOUTHERN KY. HOWEVER...IF THE NORTHWARD TREND IN THE SURFACE TRACK OCCURS...LESS SNOW WILL BE LIKELY IN THE SOUTH AND THE 2-4 INCH BAND WOULD BE DISPLACED FURTHER NORTH...PROBABLY NORTH OF THE OHIO RIVER. GIVEN THIS EVENT IS SOME 60-72 HORUS...WILL ISSUE A SPECIAL WX STMT THIS MORNING HIGHLIGHT IMPACTS OF THE EVENT. SNOW WILL LIKELY CONTINUE THURSDAY NIGHT AND DIMINISH SOME BY FRIDAY. SECONDARY CLIPPER TYPE SYSTEM IS FORECAST TO SWING THROUGH THE REGION FRIDAY AFTERNOON AND EVENING AND MAY BRING ANOTHER ROUND OF SNOW SHOWERS TO THE REGION. THUS...HAVE PRETTY MUCH LEFT ONGOING FORECAST INTACT FOR FRIDAY AND FRIDAY NIGHT. AS FOR TEMPERATURES THROUGH THE PERIOD...GENERALLY FOLLOWED A BLEND OF OP GFS RAW SFC TEMPS WITH A SPLASH OF THE MOS STAT GUIDANCE. JARVIS FORECAST FROM SATURDAY ONWARD WAS LEFT AS IS...PREVIOUS FORECAST DISCUSSION FOLLOWS... WILL STAY CLOSE TO THE EURO THROUGH THE PERIOD...WITH SOME SUPPORT FROM THE GFS THROUGH THIS PERIOD AS WELL. INDICES (PNA/EPO/AO) STILL SUPPORT THE COLDER AIR TO CONTINUE TO REPLENISH ITSELF THROUGH THE NEXT FEW WEEKS. DEEP LONGWAVE TROUGH EXTENDS FROM HUDSON BAY POLAR VORTEX(PV) ROTATING FROM THE MS VALLEY THROUGH THE OHIO VALLEY OVER THE WEEKEND...WITH POSSIBLY THE COLDEST AIR OF THE WINTER TO DATE IN THIS PERIOD. SFC HI PRESSURE MOVES ACROSS THE REGION SATURDAY INTO SUNDAY...WEAK CLIPPER STILL LOOKS POSSIBLE SUNDAY EVENING INTO EARLY MONDAY BEFORE ANOTHER VERY COLD ARCTIC AIR MASS DROPS INTO THE CENTRAL US AND INTO THE OHIO VALLEY EARLY NEXT WEEK. AS MENTIONED EARLIER IF AN SNOW COVER ON THE GROUND DURING THIS PERIOD...MAY SEE TEMPS APPROACH ZERO FOR LOWS...WILL NOT ADJUST THAT WAY AS OF NOW...BUT HAVE TRENDED COLDER THRU THE PERIOD. -SCHOTT && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 240 AM EST TUE JAN 30 2007 .SHORT TERM (TODAY-TONIGHT)... CLIPPER SHORT WAVE MOVING ESE THROUGH IOWA INTO IL/IN ATTM...WITH ASSOC SFC TROF/FRONT STRETCHING FROM NEAR IND TO PAH AS OF 6Z. MOISTURE POOLING ALONG THE FRONT...WITH DEWPOINTS RISING INTO THE MID 20S. SCT SHSN HAVE DEVELOPED ALONG/AHEAD OF THE SFC FRONT...WITH A FEW MOVING INTO THE LMK CWA AND AS FAR S AS NEAR LEITCHFIELD. RECENT ACARS DATA AT KSDF SHOW VERY STEEP LAPSE RATES TO 700MB... HELPING PROMOTE THIS PRECIP. EXPECT ISLTD-SCT SHSN TO REMAIN POSSIBLE THROUGH THE MORNING HOURS...WITH HIGHEST CHCS OVER THE N 1/2 OF THE CWA...DECREASING SOUTHWARD. ANY SNOW AMTS SHOULD BE MINOR AT BEST THOUGH SOME OF THE SHSN HAVE BEEN INTENSE OVER IL/IN/OH BASED ON RADAR REFLECTIVITIES NEAR 35DBZ OR HIGHER...SO IF SOME OF THESE WERE TO AFFECT OUR CWA THERE COULD BE LOCALIZED ACCUMS OF A COUPLE TENTHS OF AN INCH IN A SHORT PERIOD OF TIME. WILL CONTINUE TO MONITOR AS WE GET CLOSER TO THE MORNING DRIVE. BASED ON NAM/RUC...SFC FRONT WILL PASS THROUGH WRN COUNTIES AROUND 10-12Z...INTO ERN/SRN COUNTIES 12-14Z TIMEFRAME. THIS WILL BRING A ROUND OF GUSTY W/NW WINDS TODAY. BUFKIT DIAGNOSTICS INDICATE GUSTS TO 20-25KTS POSSIBLE AND THIS SEEMS REASONABLE BASED ON UPSTREAM OBSERVATIONS. THIS WILL ALSO BRING STEADY OR FALLING TEMPS (EXCEPT PERHAPS THE FAR SE COUNTIES). HAVE FOLLOWED A RUC/NAM BLEND FOR TEMPS TODAY INTO TONIGHT. CHANCES FOR SHSN WILL CONTINUE INTO THE AFTN WITH STEEP LAPSE RATES...THOUGH FEEL THAT OVERALL THREAT WILL BE LOWER THAN IN THE MORNING DUE TO SIGNIFICANTLY DRIER AIR ADVECTING INTO THE LOWER OHIO VALLEY. DEWPOINTS WILL LIKELY FALL INTO THE SINGLE DIGITS THIS AFTN. WILL WORD AFTERNOON POPS AS CHANCE VERSUS MORNING COVERAGE WORDING. GUSTY WINDS WILL LIGHTEN AFTER SUNSET...THOUGH BEFORE THAT OCCURS WIND CHILL VALUES THIS AFTN INTO THE EARLY EVENING WILL LIKELY DROP INTO THE SINGLE DIGITS WITH A FEW NEAR-ZERO VALUES POSSIBLE. HAVE ALLOWED SKIES TO CLEAR OVERNIGHT...THOUGH DID NOT GO WITH COMPLETE CLEARING SINCE NAM AND TO A LESSER EXTENT GFS SUGGEST AN AREA OF 3-5KFT CLOUDS SWEEPING ACROSS THE CWA BETWEEN 6-9Z/WED (OVERNIGHT). CS .LONG TERM (WEDNESDAY-MONDAY)... ...ACTIVE WEATHER PERIOD WITH POTENTIAL FOR ACCUMULATING SNOWS LATE WED THROUGH THURSDAY NIGHT... WEDNESDAY THROUGH FRIDAY NIGHT... FAIRLY ACTIVE AND CHALLENGING FORECAST PERIOD APPEARS TO BE IN STORE FOR THIS PART OF THE FORECAST PERIOD. LATE EVENING MODELS CONTINUE TO BE IN GENERAL AGREEMENT WITH SOUTHWESTERN U.S. UPPER LEVEL WAVE EJECTING EASTWARD DURING THE PERIOD. ALL THE MODELS INDUCE SFC CYCLOGENESIS ACROSS THE DEEP SOUTH AND BRING A SFC LOW EASTWARD ACROSS THE NORTHERN GULF STATES. THE PAST FEW RUNS OF THE MODELS HAVE BEEN TRENDING NORTHWARD WITH THE TRACK OF THE SFC LOW ACROSS THE SOUTHEAST U.S. WE STILL HAVE TWO CAMPS OF TRACKS TONIGHT...WITH THE CANADIAN GLOBAL AND NAM-WRF BEING THE FARTHEST NORTH WITH THE LOW COMING ACROSS THE FA...WHILE THE UKMET AND EURO ARE FURTHER SOUTH. THE 00Z OP GFS IS BETWEEN THESE TWO CAMPS AND OFFERS A PRETTY GOOD COMPROMISE. USING A CONSENSUS OF THE MODEL DATA...WEDNESDAY WILL GENERALLY BE A DRY DAY WITH MID-HIGH LEVEL CLOUDS INCREASING FROM WEST TO EAST. ISENTROPIC UPGLIDE WILL INCREASE WEDNESDAY EVENING AS SFC LOW BEGINS ITS TREK TOWARDS THE NORTHEAST. ANTECEDENT DRY AIRMASS WILL TAKE SOME TIME TO MOISTEN UP WEDNESDAY NIGHT SO PRECIPITATION MAY NOT START UNTIL LATE WEDNESDAY NIGHT. NONETHELESS...IT DOES APPEAR PRECIPITATION WILL BE LIKELY AND THUS HAVE INCREASED POPS TO LIKELY FOR THIS PERIOD. MODEL PROFILES FROM THE GFS SUGGEST ALL SNOW AS THE PRECIPITATION TYPE FOR WEDNESDAY NIGHT. MAIN BULK OF PRECIPITATION WILL FALL ON THURSDAY AS ISENTROPIC LIFT AND FRONTOGENETICAL FORCING WILL BE MAXIMIZED OVER KENTUCKY. BANDED PRECIPITATION WILL LIKELY LIFT NORTHWARD THROUGH THE DAY AND BE ORIENTED ALONG THE OHIO RIVER BY EVENING. HAVE GONE WITH LIKELY POPS HERE BUT PRECIPITATION TYPE WILL BE CHALLENGING. IN THE PAST SEVERAL EVENTS...WE HAVE SEEN STORMS SYSTEMS OUT IN THE LONG RANGE BEING FORECAST TO GO SOUTH...ONLY TO SEE A NORTHWARD TRACK VERIFY AS THE EVENT CAME CLOSER/UNFOLDED. IN ADDITION...THE NUMERICAL MODELS HAVE HAD A TOUGH TIME ESTIMATING THE AMOUNT OF WARM AIR ADVECTING IN ALOFT...WHICH HAS RESULTED IN MORE LIQUID PRECIPITATION OCCURRING. TONIGHT...WE ARE IN THE SAME DILEMMA. BASED ON ALL THE AVAILABLE DATA...AND NOT COMPLETELY THROWING OUT THE NAM-WRF...AM INCLINED TO LEAVE A MIX OF RAIN/SLEET/SNOW IN ACROSS THE SOUTHERN FA SOUTH OF A LINE FROM NEAR HARTFORD TO JUST SOUTH OF RICHMOND. NORTH OF THAT LINE...FEEL THAT DOMINANT PRECIPITATION TYPE WILL BE SNOW. AS SFC LOW HEADS EAST THU NIGHT...SHOULD SEE ALL AREAS GO TO SNOW. ACCUMULATIONS OF SNOW APPEAR LIKELY AT THIS TIME WITH TWO TO FOUR INCHES ACROSS THE NORTHERN HALF OF THE FA WITH ONE TO TWO ACROSS SOUTHERN KY. HOWEVER...IF THE NORTHWARD TREND IN THE SURFACE TRACK OCCURS...LESS SNOW WILL BE LIKELY IN THE SOUTH AND THE 2-4 INCH BAND WOULD BE DISPLACED FURTHER NORTH...PROBABLY NORTH OF THE OHIO RIVER. GIVEN THIS EVENT IS SOME 60-72 HORUS...WILL ISSUE A SPECIAL WX STMT THIS MORNING HIGHLIGHT IMPACTS OF THE EVENT. SNOW WILL LIKELY CONTINUE THURSDAY NIGHT AND DIMINISH SOME BY FRIDAY. SECONDARY CLIPPER TYPE SYSTEM IS FORECAST TO SWING THROUGH THE REGION FRIDAY AFTERNOON AND EVENING AND MAY BRING ANOTHER ROUND OF SNOW SHOWERS TO THE REGION. THUS...HAVE PRETTY MUCH LEFT ONGOING FORECAST INTACT FOR FRIDAY AND FRIDAY NIGHT. AS FOR TEMPERATURES THROUGH THE PERIOD...GENERALLY FOLLOWED A BLEND OF OP GFS RAW SFC TEMPS WITH A SPLASH OF THE MOS STAT GUIDANCE. JARVIS FORECAST FROM SATURDAY ONWARD WAS LEFT AS IS...PREVIOUS FORECAST DISCUSSION FOLLOWS... WILL STAY CLOSE TO THE EURO THROUGH THE PERIOD...WITH SOME SUPPORT FROM THE GFS THROUGH THIS PERIOD AS WELL. INDICES (PNA/EPO/AO) STILL SUPPORT THE COLDER AIR TO CONTINUE TO REPLENISH ITSELF THROUGH THE NEXT FEW WEEKS. DEEP LONGWAVE TROUGH EXTENDS FROM HUDSON BAY POLAR VORTEX(PV) ROTATING FROM THE MS VALLEY THROUGH THE OHIO VALLEY OVER THE WEEKEND...WITH POSSIBLY THE COLDEST AIR OF THE WINTER TO DATE IN THIS PERIOD. SFC HI PRESSURE MOVES ACROSS THE REGION SATURDAY INTO SUNDAY...WEAK CLIPPER STILL LOOKS POSSIBLE SUNDAY EVENING INTO EARLY MONDAY BEFORE ANOTHER VERY COLD ARCTIC AIR MASS DROPS INTO THE CENTRAL US AND INTO THE OHIO VALLEY EARLY NEXT WEEK. AS MENTIONED EARLIER IF AN SNOW COVER ON THE GROUND DURING THIS PERIOD...MAY SEE TEMPS APPROACH ZERO FOR LOWS...WILL NOT ADJUST THAT WAY AS OF NOW...BUT HAVE TRENDED COLDER THRU THE PERIOD. -SCHOTT && .AVIATION (06Z TAFS)... FOCUS FOR THE NEXT 6-12 HOURS IN THE TAFS CENTERS ON CHCS FOR SNOW SHOWERS ALONG WITH WIND SHIFT AS CLIPPER/COLD FRONT PASSES THROUGH THE REGION. AREA RADARS SHOW SCT SHSN OVER IL/IN...BASED ON TRENDS AND LATEST RUC/NAM DATA...A FEW OF THESE MAY AFFECT LEX/SDF TAF SITES THROUGH 15Z...THOUGH COVERAGE WILL LIKELY BE ISLTD SUCH THAT WE WILL NOT CARRY A PREVAILING SHSN GROUP IN THE TAFS...WILL RATHER HANDLE WITH TEMPOS AS NEEDED. CIGS OVER THE REGION ARE NOT TERRIBLY LOW (GENERALLY MVFR-VFR) AND PLAN ON CONTINUING THAT BASED ON FCST SOUNDINGS. SOME CIGS CLOSE TO 1-1.5KFT AGL MAY DROP INTO SRN IND AND PARTS OF CNTRL KY NORTH OF I-64 BETWEEN 12-15Z (PER NAM)...BUT WILL NOT MENTION THOSE IN THE TAFS AT THIS TIME. WINDS WILL SHIFT TO THE W/NW AS COLD FRONT PUSHES THROUGH THE AREA THIS MORNING (11-14Z TIMEFRAME). WHEN THIS HAPPENS WINDS WILL GET GUSTY (GUSTS TO 20-23KTS OR SO) FOR THE BALANCE OF THE DAYLIGHT HOURS. CS && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 1210 AM EST TUE JAN 30 2007 .AVIATION (06Z TAFS)... FOCUS FOR THE NEXT 6-12 HOURS IN THE TAFS CENTERS ON CHCS FOR SNOW SHOWERS ALONG WITH WIND SHIFT AS CLIPPER/COLD FRONT PASSES THROUGH THE REGION. AREA RADARS SHOW SCT SHSN OVER IL/IN...BASED ON TRENDS AND LATEST RUC/NAM DATA...A FEW OF THESE MAY AFFECT LEX/SDF TAF SITES THROUGH 15Z...THOUGH COVERAGE WILL LIKELY BE ISLTD SUCH THAT WE WILL NOT CARRY A PREVAILING SHSN GROUP IN THE TAFS...WILL RATHER HANDLE WITH TEMPOS AS NEEDED. CIGS OVER THE REGION ARE NOT TERRIBLY LOW (GENERALLY MVFR-VFR) AND PLAN ON CONTINUING THAT BASED ON FCST SOUNDINGS. SOME CIGS CLOSE TO 1-1.5KFT AGL MAY DROP INTO SRN IND AND PARTS OF CNTRL KY NORTH OF I-64 BETWEEN 12-15Z (PER NAM)...BUT WILL NOT MENTION THOSE IN THE TAFS AT THIS TIME. WINDS WILL SHIFT TO THE W/NW AS COLD FRONT PUSHES THROUGH THE AREA THIS MORNING (11-14Z TIMEFRAME). WHEN THIS HAPPENS WINDS WILL GET GUSTY (GUSTS TO 20-23KTS OR SO) FOR THE BALANCE OF THE DAYLIGHT HOURS. CS && .UPDATE... DOING A QUICK UPDATE TO ADD MENTION OF ISLTD -SHSN FOR SRN INDIANA OVERNIGHT. AREA OF SNOW SHOWERS OVER IL/IN WILL AFFECT NRN SECTIONS OF OUR CWA OVERNIGHT AS UPPER LEVEL SHORTWAVE DROPS SE FROM IA INTO IL. WILL ALSO INCREASE CLOUD COVER ACCORDINGLY...AND ADD MENTION OF FLURRIES FOR THE LOU/LEX VICINITIES. CS && .SHORT TERM (TONIGHT AND TUESDAY)... LONG LOOP WATER VAPOR PICTURES INDICATE YET ANOTHER CLIPPER TYPE SYSTEM DROPPING THROUGH THE UPPER MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURE HAVE SURGED INTO THE UPPER 20S AND LOWER 30S AHEAD OF A COLD FRONT LOCATED ACROSS ILLINOIS AND MISSOURI. THIS FRONT WILL SWEEP ACROSS THE FORECAST AREA BETWEEN 9-15Z TUESDAY. IN THE WAKE OF THE FRONT STEEP LAPSE RATES WILL PRODUCE ISOLATED TO SCATTERED SNOW SHOWERS. PRECIPITATION SHOULD BE LESS THAN SUNDAY MORNING AS THE ATMOSPHERE IS VERY DRY BUT A FEW LOCATIONS ACROSS THE BLUEGRASS REGION MAY SEE UP TO A HALF INCH OF SNOW IN HEAVIER SHOWERS. COLD AIR WILL ADVECT INTO THE AREA TUESDAY AFTERNOON AND I HAVE GONE SEVERAL DEGREES BELOW MOS HIGHS TUESDAY WITH THE WARMEST TEMPERATURES OCCURING IN THE MORNING AND FALLING TEMPERATURES DURING THE AFTERNOON. FOR TONIGHT WE WILL SEE PARTLY CLOUDY SKIES AND WESTERLY WINDS. MOS TEMPERATURES FOR THIS PERIOD LOOK GOOD. --JA .LONG TERM (TUESDAY NIGHT THROUGH MONDAY)... TUESDAY NIGHT THROUGH WEDNESDAY... GREAT CONFIDENCE IN THIS PERIOD AS NEARLY UNANIMOUS SOLUTION AMONG THE SHORT RANGE MODELS. WILL USED THE 09Z SREF AS A BASIS FOR THE FORECAST AND HOURLY GRIDS...THOUGH LITTLE IF ANY CHANGE FROM PREVIOUS FORECAST. TUESDAY NIGHT SHORTWAVE TROUGH WILL BE EXITING ACROSS THE APPALACHIANS AS LARGE AREA OF SFC HI PRESSURE WORKS EAST INTO THE OHIO VALLEY. BEHIND THE TROUGH ANOTHER REINFORCING SHOT OF COLDER AIR. SFC HI PRESSURE MOVES ACROSS THE REGION WEDNESDAY...SOME HIGH CLOUDS WILL START TO STREAM ACROSS THE SKIES DURING THE AFTERNOON INTO THE EVENING HOURS AHEAD OF DEVELOPING SOUTHERN SYSTEM. LOWS WEDNESDAY MORNING WILL DROP INTO THE LOWER TO MIDDLE TEENS. THURSDAY AND FRIDAY... AS MENTIONED YESTERDAY...THESE TWO DAYS ARE THE BIGGEST CHALLENGE IN THE FORECAST THROUGH THE NEXT WEEK DUE TO JUMPY MODELS AND THE ALWAYS PRESENT POSSIBILITY THAT MODELS ARE UNDERPLAYING THE STRENGTH OF SOUTHERN FLOW AHEAD OF THE SYSTEM AND CONTAIN A COLD BIAS ALOFT...THIS ESPECIALLY GOES FOR THE GFS. ONE THING THAT DOES ADD MUCH MORE CONFIDENCE TO THE FORECAST AS A WHOLE IS THE SOLUTIONS HAVE CONVERGED SOMEWHAT FOR EACH DAY...ESPECIALLY THE 12Z ECMWF AND 12Z GFS RUNS FROM TODAY. THEREFORE WILL USE A BLEND OF THE TWO FOR THIS 48 HOUR PERIOD. THE CANADIAN IS NOT TOO FAR OFF BUT HAS A SLIGHTLY WEAKER SOLUTION...BUT THE UKMET DOES LEND SOME SUPPORT TO THE BLENDED SOLUTION ALLOWING FOR SLIGHTLY INCREASED CONFIDENCE OF THEIR SOLUTIONS. EARLY THURSDAY...ISENTROPIC LIFT IS VERY APPARENT IN BOTH THE GFS AND THE NAM THRU EARLY AFTERNOON...ESPECIALLY IN THE 280 TO 290K SURFACES...AS WELL AS MOISTURE TRANSPORT INTO THE REGION. SOME UNCERTAINTY WILL EXIST TO HOW LONG IT TAKES FOR THE VERY DRY LOW LEVELS TO MOISTEN UP...WOULD THINK THAT NO PRECIP SHOULD REACH GROUND UNTIL THE EARLY MORNING HOURS...MAINLY AFTER 1AM TO 4AM ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA...SPREADING EAST AFTER 7AM. MODEST FRONTOGENETICAL FORCING ACROSS THE REGION...WHICH WOULD BE MAXIMIZED ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA THURSDAY MORNING...THEN ACROSS THE ENTIRE AREA EAST OF I-65 FROM THE LATE MORNING INTO THE AFTERNOON. ALONG WITH A 130 TO 140KT JET STREAK PASSING ACROSS THE MID OHIO VALLEY DURING THE MORNING INTO THE AFTERNOON THURSDAY. ALL TOGETHER IT MEANS A DECENT SHOT A SOME ACCUMULATING SNOW ACROSS THE FORECAST AREA...CURRENTLY THE HIGHEST POSSIBLE ACCUMS LOOK TO BE ACROSS THE SOUTHERN PORTIONS OF THE AREA SOUTH OF A LINE FROM HARTFORD TO RICHMOND. FORECAST SOUNDINGS INDICATE THE DOMINATE PRECIP TYPE TO BE SNOW...THOUGH AS MENTIONED EARLIER WILL HAVE TO WATCH FOR TREND OF STRONGER SW WINDS ALOFT WHICH MAY CREATE MORE OF A MIX ACROSS SOUTH CENTRAL KENTUCKY. AS USUAL AT 3 DAYS OUT OR MORE SOME CHANGES IN TRACK CAN BE EXPECTED IF THE TRACK SHIFTS SLIGHTLY FURTHER NORTH THEN MORE MOISTURE MAY BE BROUGHT INTO THE REGION AND BETTER CHANCES FOR MORE SNOW...LIQUID EQUIV CURRENTLY SUGGEST THAT SOUTHERN KY MAY SEE 1 TO 3 INCHES IF NO MIX WERE TO OCCUR...WITH AROUND AN INCH NORTH OF THERE AT THIS TIME. ENOUGH COLD AIR SHOULD BE IN PLACE ACROSS THE NORTHERN PORTIONS OF THE FORECAST AREA SO A MIX IS VERY UNLIKELY AS FORECAST SOUNDINGS ALOFT NEVER WARM HIGHER THAN -2C DUE TO THE LOW LEVEL JET. HAVE UNDERCUT MOS TEMPS HERE WITH EVAP COOLING AND CLOUDS/PRECIP IN PLACE DURING THE PEAK HEATING HOURS. FRIDAY IS A DIFFERENT STORY WITH RESPECT TO CONFIDENCE...THOUGH THE MODELS HAVE CLOSED SOMEWHAT ON A SOLUTION. STILL MUCH MORE UNCERTAINTY HERE THAN ON THURSDAY. GFS LOOKS ODD...IF YOU USE THE HIGHER RESOLUTION VERSION SAY 40KM...PULL BACK TO THE 90KM VERSION AND IT LOOKS MUCH LIKE THE 12Z EURO SOLUTION. OVERALL LESSER CHANCES FOR ACCUMS ON FRIDAY BUT STILL A CHANCE FOR LIGHT SNOW AS A FRONT WILL SWING THRU THE REGION DURING THE MORNING OR AFTERNOON. MODEST FRONTOGENETICAL FORCING SEEN THROUGH EARLY AFTERNOON AND STRONG JET STREAK MAY HELP WITH LIFT...ONLY CONCERN LOOKS TO BE MOISTURE SO HAVE LOWERED POPS TO 30 ACROSS THE REGION. TEMPERATURES WILL START TO TUMBLE FROM FRIDAY INTO THE WEEKEND AS ARCTIC AIR WORKS ACROSS THE REGION. IF ANY SIGNIFICANT SNOWCOVER EXISTS THEN WE WILL HAVE TO LOWER TEMPERATURES FROM FRIDAY THRU THE EARLY PORTIONS OF NEXT WEEK. SATURDAY INTO EARLY NEXT WEEK... WILL STAY CLOSE TO THE EURO THROUGH THE PERIOD...WITH SOME SUPPORT FROM THE GFS THROUGH THIS PERIOD AS WELL. INDICES (PNA/EPO/AO) STILL SUPPORT THE COLDER AIR TO CONTINUE TO REPLENISH ITSELF THROUGH THE NEXT FEW WEEKS. DEEP LONGWAVE TROUGH EXTENDS FROM HUDSON BAY POLAR VORTEX(PV) ROTATING FROM THE MS VALLEY THROUGH THE OHIO VALLEY OVER THE WEEKEND...WITH POSSIBLY THE COLDEST AIR OF THE WINTER TO DATE IN THIS PERIOD. SFC HI PRESSURE MOVES ACROSS THE REGION SATURDAY INTO SUNDAY...WEAK CLIPPER STILL LOOKS POSSIBLE SUNDAY EVENING INTO EARLY MONDAY BEFORE ANOTHER VERY COLD ARCTIC AIR MASS DROPS INTO THE CENTRAL US AND INTO THE OHIO VALLEY EARLY NEXT WEEK. AS MENTIONED EARLIER IF AN SNOW COVER ON THE GROUND DURING THIS PERIOD...MAY SEE TEMPS APPROACH ZERO FOR LOWS...WILL NOT ADJUST THAT WAY AS OF NOW...BUT HAVE TRENDED COLDER THRU THE PERIOD. SCHOTT && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 945 PM CST MON JAN 29 2007 .DISCUSSION... CLOUD COVER A PLENTY THIS EVENING WITH THE PRESENCE OF A 150KT SUBTROPICAL JET OVERHEAD. WATER VAPOR LOOP INDICATES A SUBTLE SHORTWAVE ADVANCING E ACROSS THE TX BIG BEND REGION ATTM...WHICH WILL TRANSLATE E ACROSS CENTRAL/SE TX OVERNIGHT INTO S LA BY DAYBREAK TUESDAY. LOWERING CIGS ACROSS E TX HAS PROVIDED A BLANKET OVER THESE AREAS...WITH 3Z TEMPS SOME 5 DEGREES WARMER THAN OVER THE REST OF THE AREA. MIN TEMP FORECAST WILL BE TRICKY TONIGHT...AS CIGS WILL LOWER A BIT ELSEWHERE OVERNIGHT AS THE SHORTWAVE APPROACHES...THUS TEMPS SHOULD ONLY DROP SEVERAL MORE DEGREES OR SO THROUGH 12Z. THE NEW 00Z NAM RUN NOW INDICATES LITTLE IF ANY ISENTROPIC LIFT DEVELOPING AFTER 6Z OVER SE TX/SW LA...ALTHOUGH THE RUC MAINTAINS CONSISTENCY IN THE EARLIER MODEL RUNS OF GENERATING ISENTROPIC LIFT/LOWERING CONDENSATION PRESSURE DEFICITS ALONG THE 295-300K SURFACES...SIMILAR TO THE 18Z GFS RUN. PSN PROFILER INDICATING GOOD 30KT SW FETCH BETWEEN 1-2KM...THUS BELIEVE THE ISENTROPIC LIFT/-RA WILL DEVELOP AFTER 6Z IN VC OF THE MIDDLE TX COAST...WHICH WILL INCREASE ACROSS SE TX/SW LA OVERNIGHT...BRUSHING THE S ZONES. HAVE RAISED POPS A TAD TO LOW CHANCE AFTER 6Z FOR DEEP E TX AND PORTIONS OF WCNTRL LA...AND MAINTAINED SLIGHT CHANCE POPS FOR THE EXTREME SE ZONES. BUT HAVE REMOVED POPS FOR TYR/GGG AREAS AS BEST FORCING WILL REMAIN S OF THESE AREAS. ALSO REMOVED TEMPORAL SKY CONDITION WORDING AND ADJUSTED MIN TEMPS UP A TAD TO ACCOMMODATE SLOW FALL THIS EVENING. OTHERWISE...BUILDING CANADIAN SURFACE RIDGE OVER THE PLAINS WILL FORCE ANOTHER REINFORCING COLD FRONT SE INTO THE AREA OVERNIGHT...THUS SHIFTING THE RAIN AREA QUICKLY OUT OF THE S SECTIONS OF THE FORECAST AREA TUESDAY. REMAINDER OF THE FORECAST IS IN GOOD SHAPE. UPDATE ALREADY OUT. 15 && .AVIATION... MOSTLY VFR CONDITIONS THROUGH 31/00Z. HOWEVER...EXPECT MARGINAL CONDITIONS VICINITY LFK BETWEEN 06Z AND 18Z. COLD FRONT ACROSS SOUTHEAST OKLAHOMA THIS EVENING WILL CONTINUE TO MOVE SOUTHEAST TO THE INTERSTATE 30 CORRIDOR BY 08Z. THE FRONT WILL BRING CIGS NEAR 5 THOUSAND. WIDESPREAD CIGS NEAR 5 THOUSAND WILL ALSO FORM AHEAD OF THE FRONT BY 06Z...OCCASIONALLY LOWERING TO AROUND 15 HUNDRED FEET LFK TO AEX LINE AFT 08Z. VSBYS MAY BRIEFLY FALL TO NEAR 3 MILES IN LIGHT RAIN SOUTHERN SECTIONS AFT 08Z. CIGS AND VSBYS WILL IMPROVE SOUTHERN SECTIONS AFT 18Z. EXPECT SOUTHERLY WINDS 5 TO 10 KNOTS AHEAD OF THE FRONT...BECOMING NORTH TO NORTHEAST BETWEEN 08Z AND 12Z BEHIND THE FRONT. /14/ && .PRELIMINARY POINT TEMPS/POPS... SHV 36 44 28 41 / 10 10 10 20 MLU 34 43 28 43 / 10 30 10 10 DEQ 29 44 24 41 / 10 10 10 30 TXK 32 44 27 42 / 10 10 10 20 ELD 31 43 24 42 / 10 20 10 20 TYR 37 45 30 42 / 10 20 10 30 GGG 36 44 27 41 / 10 20 10 20 LFK 40 46 33 44 / 30 20 10 20 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...NONE. LA...NONE. OK...NONE. TX...NONE. && $$ 15/14 la AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE CARIBOU ME 1023 AM EST MON JAN 29 2007 .SYNOPSIS... THE COMBINATION OF LOW PRESSURE OVER THE MARITIMES AND HIGH PRESSURE TO THE WEST WILL USHER IN MORE COLD ARCTIC AIR FROM THE NORTHWEST TODAY INTO TUESDAY. ANOTHER WEAK LOW PRESSURE SYSTEM WILL PASS SOUTH OF THE REGION ON TUESDAY WITH HIGH PRESSURE BUILDING ACROSS THE REGION TUESDAY NIGHT INTO WEDNESDAY. && .UPDATE... BASED ON VISIBLE SATELLITE SHOWING A LACK OF CLOUDS UPSTREAM AND DRY LOW LEVELS PER MORNING SOUNDING DECIDED TO REMOVE ANY MENTION OF SNOW SHOWERS TODAY. ALSO CUT BACK ON CLOUDS THIS AFTERNOON ACROSS THE NORTH. SAT SHOWS CLOUDS ASSOCIATED WITH OCEAN LOW BACKING IN TOWARD THE COAST SO WENT PARTLY CLOUDY HERE. REST OF FORECAST LOOKS GOOD AND NO OTHER CHANGES ATTM. UPDATED AFM/PFM/ZFP ALREADY SENT. && .PREV DISCUSSION... SHORT TERM /TODAY THROUGH TUESDAY/... ANOTHER SURGE OF ARCTIC AIR SET TO INVADE THE CWA LATER TODAY INTO TUESDAY. SO THEREFORE...THE MAIN FOCUS THIS FCST PACKAGE IN TEMPERATURES AND HOW EXTENSIVE WILL CLOUDS BE. USED THE GFS PRIMARILY INTO TUESDAY W/UPPER VORTEX MOVING THROUGH THE CWA & VORT MAX ROTATING THROUGH. GFS MATCHED WELL PER 00Z UA. ONE CAVEAT IS I DID LOAD IN THE NAM12 FOR THE SKY GRIDS FOR THE 1ST 12 HRS OF THE FCST BASED ON ITS HANDLING OF THINGS OVER THE PAST 6 HRS PER IR SATL IMAGERY. AFT THAT...THE GFS WAS USED W/ADJUSTMENTS DOWNWARD ESP TONIGHT. THE EXCEPTIONS WILL BE ALONG THE MTNS OUT W & OVER THE COASTAL WATERS WHERE CLOUD COVER WILL HANG ON W/COLD AIR IN NWLY FLOW. ADDED SCTD SNOW SHOWERS TODAY INTO THE EVENING ACROSS THE N & W. NO HIGHER THAN 30% POP. NOW FOR THE TEMPERATURES...MAV MOS HAS BEEN PRETTY REASONABLE...HOWEVER IT IS UNDERDONE ON TEMPERATURES ATTM. DECISION WAS TO USE THE GFS 2M TEMPERATURES W/SOME ADJUSTMENTS ON THE UPWARD END FOR MINS TONIGHT AS WINDS COULD STAY UP ENOUGH TO ALLOW FOR SOME MIXING. ANYWAY...THINKING IS THAT NORMALLY COLDER AREAS LIKE SAINT JOHN VALLEY...WRN AREAS & NRN WASHINGTON COUNTY WILL SEE MINS TONIGHT BOTTOMING BETWEEN -15 TO -20F W/SOME SITES POSSIBLY HITTING LOWER. WENT BELOW ZERO ALL THE WAY DOWN TO DOWNEAST AREAS W/THE EXCEPTION OF THE IMMEDIATE COAST AS TEMPERATURES WILL HOVER AROUND ZERO. PREV FCST MAXES LOOKED GOOD & ONLY MADE SOME MINOR ADJUSTMENTS AND THIS WAS FOR TUESDAY W/THIS ARCTIC AIRMASS BECOMING ENTRENCHED. LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... WEAK HIGH PRESSURE FORECASTED TO BUILD ACROSS NEW ENGLAND TUESDAY NIGHT INTO WEDNESDAY. MODELS CONTINUE TO INDICATE UPPER TROUGH TO CROSS MAINE DURING THE DAY ON WEDNESDAY BUT WITH LIMITED MOISTURE ONLY EXPECTED ISOLATED SNOW SHOWERS OR FLURRIES DURING WEDNESDAY AFTERNOON WITH THIS DISTURBANCE. WEAK WARM AIR ADVECTION PATTERN WILL SETUP OVER THE REGION ON THURSDAY BUT AGAIN WITH LIMITED MOISTURE AND ZONAL FLOW ALOFT WILL KEEP POPS BELOW 50 PERCENT WITH HIGHEST VALUES OVER THE NORTHWEST SECTIONS. MEDIUM RANGE MODELS CONTINUE TO HINT AT A SYSTEM FOR THE END OF THE WEEK. BOTH GFS AND ECMWF PLACE A LOW OVER THE GREAT LAKES CONNECTED WITH A LOW OFF THE EAST COAST. THE LOW PRESSURE TROUGH BETWEEN THESE TWO LOWS MAY MOVE THROUGH THE STATE FRIDAY NIGHT INTO EARLY SATURDAY WITH A PERIOD OF SNOW AS THE ENTIRE PATTERN ROTATES NORTHEAST THROUGH THE AREA. AVIATION /07Z-06Z/... LOOKS LIKE VFR RIGHT THROUGH THE PERIOD. MARINE... KEPT THE SCA IN PLACE AS IT LOOKS LIKE THINGS ARE READY TO GO INTO THE CATEGORY. PREV FCST PACKAGE RIGHT ON ESP W/THE WAVE HEIGHTS. MEDIUM RANGE GUIDANCE INCLUDING NAM12 & RUC RUNNING TOO LOW ON WINDS. 20-25 KTS LOOKS GOOD INTO TONIGHT W/SURGE OF THAT ARCTIC AIR ON NW WINDS. WNA RUNNING TOO LOW BY AT LEAST A FOOT. WAVE HEIGHTS RUNNING 5 FT LOOKS TO BE A GOOD BET. SEA SPRAY NOMOGRAM SHOWS FREEZING SPRAY TO BE LIGHT THROUGH THE PERIOD. DAY CREW CAN ASSESS THIS MORE W/LATER GUIDANCE. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST TUESDAY FOR ANZ050. && $$ SHORT TERM...DUDA me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 208 PM EST TUE JAN 30 2007 .SHORT TERM /TONIGHT THROUGH WEDNESDAY/... RUC AND NAM-WRF SHOW THAT THE COLD FRONT ASSOCIATED WITH THE CLIPPER-TYPE LOW PRESSURE SYSTEM WILL HAVE MOVED THROUGH THE UPPER OHIO VALLEY BY EVENING. HENCE, TONIGHT THE UPPER OHIO VALLEY WILL BE MAINLY AFFECTED BY POSTFRONTAL COLD-ADVECTION LIFT/INSTABILITY AND LAKE-ENHANCED SNOW SHOWERS. THIS WILL GENERATE SNOW ACCUMULATIONS ON THE ORDER OF AN INCH FOR MOST PLACES, BUT AS MUCH AS 3 INCHES NEAR THE MOUNTAINS AND ALONG THE INTERSTATE 80 CORRIDOR. BASED ON NAM-WRF FORECAST SOUNDINGS, EXPECT THE UNSTABLE BOUNDARY LAYER TO SHRINK TO A HEIGHT OF LESS THAN 6 KFT AGL AFTER MIDNIGHT. THEREFORE, THE PRECIPITATION WILL DIMINISH TO MAINLY FLURRIES BY WEDNESDAY DAYTIME. SO WILL KEEP ENDING TIME OF CURRENT SNOW/LAKE SNOW ADVISORIES AS IS. FOR TEMPERATURES, WILL KEEP WITH RECENT NAM AND GFS MOS VALUES. WINDS WILL BE MAINLY WESTERLY INTO WEDNESDAY AT 10 TO 15 MPH, ALBEIT SOME GUSTS CAN BRIEFLY REACH 20-25 MPH. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... RECENT GFS AND ECMWF MODEL RUNS SHOW LITTLE CHANGE IN THE CURRENT UPPER FLOW PATTERN OVER NORTH AMERICA OVER THE NEXT WEEK, AND PERHAPS INTO MID FEBRUARY, WITH A CLOSED UPPER LOW OVER EASTERN CANADA PROVIDING A CYCLONIC NORTHWEST FLOW ACROSS THE GREAT LAKES AND UPPER OHIO VALLEY. SO THE CURRENT EPISODE OF COLDER THAN NORMAL TEMPERATURES AND ACCOMPANYING CLIPPER-RELATED PERIODS OF LIGHT BUT PESKY SNOW SHOWERS WILL BE THE RULE INTO NEXT WEEK. IT DOES APPEAR THE START OF NEXT WEEK WILL BE COLDER THAN THIS WEEK AS 850MB TEMPERATURES WILL BE FREQUENTLY COLDER THAN M20C AND SURFACE TEMPERATURES WILL BE MAINLY IN THE ZERO TO 15 ABOVE RANGE AS INDICATED BY RECENT HPC GUIDANCE AND GFS MOS VALUES. && .AVIATION /19Z-18Z/... COLD FRONT IS CROSSING PITTSBURGH AT THE MOMENT BRINGING A BAND OF HEAVIER SNOW SHOWERS. SNOW SHOWERS ARE KEEPING CONDITIONS IN THE IFR RANGE WITH VISIBILITIES AROUND 2SM OR LOWER. CEILINGS ARE GENERALLY MVFR RANGING FROM 1000 TO 2000 FEET. THESE CONDITIONS SHOULD CONTINUE THROUGH THE NIGHT EXCEPT FOR THE VISIBILITIES IMPROVING TO MVFR OR VFR OVERNIGHT AS THE SNOW SHOWERS MOVE IN AND OUT OF THE AIRPORT AREAS AND DECREASE IN COVERAGE BY DAYTIME WEDNESDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...SNOW ADVISORY UNTIL 7 AM EST WEDNESDAY FOR MDZ001. OH...NONE. PA...SNOW ADVISORY UNTIL 7 AM EST WEDNESDAY FOR PAZ030-032. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST WEDNESDAY FOR PAZ007>009. WV...SNOW ADVISORY UNTIL 7 AM EST WEDNESDAY FOR WVZ023-041. && $$ 66/11/66/ md AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1248 PM EST TUE JAN 30 2007 .MARINE... WNDS ABV SCA CRITERIA AT TPLM2...AND GUSTS ARND 20 KT REPORTED AT ERN MTR SITES. SEEMS THO SUFFICIENT MIXING TAKING PLACE IN SPITE OF IMPENDING CLDCVR AND COLD WATER. WL RAISE FLAGS NOW...AND FIRE OFF A QUICK MARINE UPDT. && .AVIATION /18Z-18Z/... VFR CONDS WL PREVAIL...W/ CHC -SHSN ALL SITES XCPT CHO LT AFTN INVOF FROPA. SHUD HV LTL TO NO VSBY RESTRICTIONS...AND THUS NO OPERATIONAL IMPACT. SLY FLOW /G20 KT/ WL VEER NW BY 00Z. HIER GUSTS PROBABLE...SPCLY RIGHT BHD FROPA. && .PREV DISCUSSION... /ISSUED 1005 AM EST TUE JAN 30 2007/ SHORT TERM /REST OF TODAY/... VORT MAX CNTRD IN SRN OH ATTM PER VAPOR LOOP. RGNL RADARS DEPICT SHSN HAS SPREAD E OF THAT TO THE WRN RDGS OF CWFA. AFTR GLANCING AT 12Z RUNS OF RUC AND NAM...IT APPRS THAT MOST OF THE DEEP MSTR WL BE CONFINED TO THOSE RDGS. TRACK OF SHEARED VORT WL BE W-E ACRS CWFA...PASSING NEAR OF JUST N OF DC. SFC REFLECTION WL CROSS PA... WELL N OF US. THUS...DONT HV MUCH HOPE THAT SNW WL FALL E OF FVRD UPSLOPE TRRN. GOING FCST CVRS THAT. WL HOLD ONTO SNW ADVY AREA AS THESE ZNS CARRY HIEST RISK. AM A LTL CONCERNED THAT MAXT MAY BE A CPL TICKS TOO HIGH PER MRNG RAOBS. BUT DUE TO AMPLE SUN ATTM AND BRIEF PD OF SW FLOW AHD OF S/WV...WL LV THAT AS IS ALSO. THUS...HV TOUCHED UP A FEW GRIDS...BUT NO UPDT TO TXT PRODUCTS XPCTD ATTM. AVIATION /15Z-12Z/... VFR CONDS THRU PD...W/ 5000 FT CIGS LT TAFTN-ELY EVE. MAYBE A PD OF FLURRIES AT MRB AS CLIPPER PASSES N OF AREA. CUD EVEN BE A FLURRY OR TWO DC-BALT AREA AIRPORTS...BUT RISK TOO SLIM FOR TAF MNTN. SHUD HV NO IMPACT TO OPS. MARINE... LGT SLY FLOW AHD OF CLIPPER SYSTM. WNDS WL VEER NW AND PICK UP TNGT IN WAKE OF SYSTM. WL HOLD ONTO SCA HEADLINE FOR TNGT. PREV DISCUSSION... /ISSUED 320 AM EST TUE JAN 30 2007/ SHORT TERM /TODAY THROUGH TUESDAY NIGHT/... A BIT OF A COMPLEX FORECAST WITH SOME CONFLICTING INFO FROM THE MODELS ABOUT A CLIPPER COMING THROUGH THIS AFTERNOON. THE SFC LOW WAS MOVING THRU THE MIDWEST EARLY THIS MORNING AND PRESSING EAST. IT WILL BE SLOWLY STRENGTHENING AS IT MOVES THROUGH OUR AREA AND OUT OVER THE OCEAN. THE VORT ASSOCIATED WITH IT IS SHEARED VORTICITY MOVING ACROSS THE MID ATL AND NOT A STRONG PACKET SO NOT IMPRESSED WITH SNOWFALL POTENTIAL EAST OF THE MTNS. THERE IS SOME FN VECTR CONVERGENCE BETWEEN 700 AND 500MB THAT EXTENDS S FROM THE VORT MOVING THROUGH LIKE A COLD FRONT DURING THE AFTERNOON. THAT IS ONE INDICATOR THAT A SMALL SNOW BAND COULD MOVE THROUGH IN THE AFTERNOON. HOWEVER WITH THE SHEARED VORT THAT MOVES EAST THRU DC... THE BEST CHC WOULD BE N OF THAT AND WITH THE SHEARED NATURE OF THE SYSTEM... A SLIM CHC EVEN THERE. ALSO HIGH TEMPS TODAY ARE FORECAST ABOVE FREEZING EXCEPT FOR AT ELEVATION... AND CURRENT RADAR EXTENT OF THE SYSTEM IS LIMITED. PUT ALL OF THAT TOGETHER AND THE BEST CHC IS THAT NO MEASURABLE SNOW MAKES IT EAST OF THE MTNS. THERE IS AROUND A 30 PERCENT CHC FOR A DUSTING FOR THE N TIER OF MD... AND AN EVEN SMALLER 10-20 PERCENT CHC OF A DUSTING SOUTH OF THAT. ONCE THE CLIPPER ROLLS THRU... SKIES CLEAR OUT AGAIN AND NW WINDS KICK UP AGAIN BRINGING COLD TEMPS AROUND 20 FOR MANY BY WED MORNING WITH WIND CHILLS BACK DOWN AROUND ZERO IN THE WESTERN MOUNTAINS AND IN THE TEENS AND SINGLE DIGITS FOR THE REST. IN THE WESTERN UPSLOPE AREAS OF W GRANT W MINERAL AND W ALLEGANY COUNTIES THERE WILL BE A SNOW ADV ISSUED FOR THIS AFTERNOON AND OVERNIGHT. 1 TO 3 INCHES WILL LIKELY PILE UP AGAIN AS SNOW SHOWERS RETURN. AVIATION /09Z-12Z/... VFR CONDITIONS EXPECTED THRU THE TAF PERIOD FOR THE MOST PART. MAY BRIEFLY TOUCH MVFR CONDTIONS WHEN THE CLIPPER ACTUALLY MOVES THRU IN THE AFTERNOON... BUT BETTER CHC THAT IT WILL REMAIN VFR. SW WINDS WILL FLIP TO NW AND BECOME GUSTY AGAIN THIS EVENING AND TONIGHT. SNOW SHOWERS IN THE MOUNTAINS WILL BE REFLECTED IN THE TWEBS. THERE IS A SLIGHT CHC OF A CONVECTIVE BAND OF SNOW SHOWERS DEVELOPING ALONG THE CLIPPER...BUT AGAIN A BETTER CHC THAT SNOW SHOWERS WILL NOT MAKE IT EAST OF THE MOUNTAINS. MARINE... AFTER THE CLIPPER LOW MOVES THRU AND STRENGTHENS A LITTLE BIT WINDS WILL KICK UP ONCE AGAIN AND A SMALL CRAFT ADVISORY IS IN PLACE FOR 9 PM TONIGHT THROUGH 10 AM WEDNESDAY. SMALL CRAFT ADVISORY CONDITIONS THIS WEEKEND IN THE WAKE OF THE LOW PRESSURE SYSTEM AFFECTING THE WATERS THURSDAY NIGHT. LONG TERM /WEDNESDAY THROUGH MONDAY/... BUSY MEDIUM RANGE FORECAST WITH A LOW PRESSURE SYSTEM MAKING ITS WAY FROM THE CENTRAL GULF COAST NORTHEAST ACROSS THE MID ATLANTIC STATES THURSDAY NIGHT. HIGH PRESSURE WILL PUSH THIS SYSTEM OUT TO SEA FOR THE WEEKEND...PROVIDING COOL AND DRY CONDITIONS FOR MOST LOCATIONS THROUGH THE END OF THE FORECAST PERIOD. THE EXCEPTION WILL BE CONTINUED CHANCES FOR UPSLOPE SHOWERS WEST OF THE ALLEGANY FRONT. MAIN FORECAST CHALLENGE IS WITH THE SOUTHERN STREAM LOW APPROACHING THURSDAY. MODELS CONTINUE THEIR INCONSISTENCIES WITH THIS SYSTEM FROM TIMING AND LOCATION TO PRECIPITATION TYPE. WHILE THE TRACK OF THE ACTUAL LOW IS STILL UNCERTAIN...BUT GUIDANCE COMES BACK IN LINE WITH THE LOW PLACED OFF THE NORTHERN MID ATLANTIC COAST FRIDAY MORNING AT 12Z. THE ECMWF IS THE FASTER MODEL WHILE THE NAM IS THE SLOWEST AND THE GFS IN BETWEEN. TOOK A BLEND OF THE THREE USING THE GFS. WHILE EARLIER RUNS BROUGHT PRECIPITATION IN FASTER...GUIDANCE HAS SINCE BACKED OFF. EXPECT PRECIPITATION TO SPREAD NORTHEAST ACROSS THE FORECAST AREA THURSDAY AFTERNOON...WITH HIGHEST POPS MOST LIKELY THURSDAY NIGHT. PRECIPITATION TYPES WITH THIS SYSTEM WILL BE INTERESTING TO WATCH OVER THE NEXT DAY OR TWO. WITH THE VARYING TRACKS OF THE LOW...TYPE FORECASTING HAS BEEN MORE OF A CHALLENGE. USING HPC GUIDANCE AND BUFKIT MODEL SOUNDINGS...A CHANGE OVER FROM SNOW TO FREEZING RAIN IS A POSSIBILITY ACROSS THE CENTRAL FORECAST AREA...AND SWITCHING FROM SNOW TO RAIN IN THE FAR NORTHEAST. HAVE ADDED THE MENTION OF SNOW AND FREEZING RAIN TO THE GRIDS FOR WASHINGTON DC WEST TO THE BLUE RIDGE AND SOUTH THROUGH THE SHENANDOAH VALLEY...WITH A RAIN AND SNOW MIX ACROSS BALTIMORE. CONFIDENCE WITH PRECIPITATION TYPE IS LOW GIVEN VARIANCE OF RECENT MODEL RUNS...SO THIS WILL MOST LIKELY CHANGE OVER THE NEXT 24 TO 48 HOURS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...SNOW ADVISORY UNTIL 7 AM EST WEDNESDAY FOR MDZ501. VA...NONE. WV...SNOW ADVISORY UNTIL 7 AM EST WEDNESDAY FOR WVZ501-503. MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST WEDNESDAY FOR ANZ530>537. && $$ UPDATES...HTS ORIGINAL DISCUSSION...STRONG/SAR md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1005 AM EST TUE JAN 30 2007 .SHORT TERM /REST OF TODAY/... VORT MAX CNTRD IN SRN OH ATTM PER VAPOR LOOP. RGNL RADARS DEPICT SHSN HAS SPREAD E OF THAT TO THE WRN RDGS OF CWFA. AFTR GLANCING AT 12Z RUNS OF RUC AND NAM...IT APPRS THAT MOST OF THE DEEP MSTR WL BE CONFINED TO THOSE RDGS. TRACK OF SHEARED VORT WL BE W-E ACRS CWFA...PASSING NEAR OF JUST N OF DC. SFC REFLECTION WL CROSS PA... WELL N OF US. THUS...DONT HV MUCH HOPE THAT SNW WL FALL E OF FVRD UPSLOPE TRRN. GOING FCST CVRS THAT. WL HOLD ONTO SNW ADVY AREA AS THESE ZNS CARRY HIEST RISK. AM A LTL CONCERNED THAT MAXT MAY BE A CPL TICKS TOO HIGH PER MRNG RAOBS. BUT DUE TO AMPLE SUN ATTM AND BRIEF PD OF SW FLOW AHD OF S/WV...WL LV THAT AS IS ALSO. THUS...HV TOUCHED UP A FEW GRIDS...BUT NO UPDT TO TXT PRODUCTS XPCTD ATTM. && .AVIATION /15Z-12Z/... VFR CONDS THRU PD...W/ 5000 FT CIGS LT TAFTN-ELY EVE. MAYBE A PD OF FLURRIES AT MRB AS CLIPPER PASSES N OF AREA. CUD EVEN BE A FLURRY OR TWO DC-BALT AREA AIRPORTS...BUT RISK TOO SLIM FOR TAF MNTN. SHUD HV NO IMPACT TO OPS. && .MARINE... LGT SLY FLOW AHD OF CLIPPER SYSTM. WNDS WL VEER NW AND PICK UP TNGT IN WAKE OF SYSTM. WL HOLD ONTO SCA HEADLINE FOR TNGT. && .PREV DISCUSSION... /ISSUED 320 AM EST TUE JAN 30 2007/ SHORT TERM /TODAY THROUGH TUESDAY NIGHT/... A BIT OF A COMPLEX FORECAST WITH SOME CONFLICTING INFO FROM THE MODELS ABOUT A CLIPPER COMING THROUGH THIS AFTERNOON. THE SFC LOW WAS MOVING THRU THE MIDWEST EARLY THIS MORNING AND PRESSING EAST. IT WILL BE SLOWLY STRENGTHENING AS IT MOVES THROUGH OUR AREA AND OUT OVER THE OCEAN. THE VORT ASSOCIATED WITH IT IS SHEARED VORTICITY MOVING ACROSS THE MID ATL AND NOT A STRONG PACKET SO NOT IMPRESSED WITH SNOWFALL POTENTIAL EAST OF THE MTNS. THERE IS SOME FN VECTR CONVERGENCE BETWEEN 700 AND 500MB THAT EXTENDS S FROM THE VORT MOVING THROUGH LIKE A COLD FRONT DURING THE AFTERNOON. THAT IS ONE INDICATOR THAT A SMALL SNOW BAND COULD MOVE THROUGH IN THE AFTERNOON. HOWEVER WITH THE SHEARED VORT THAT MOVES EAST THRU DC... THE BEST CHC WOULD BE N OF THAT AND WITH THE SHEARED NATURE OF THE SYSTEM... A SLIM CHC EVEN THERE. ALSO HIGH TEMPS TODAY ARE FORECAST ABOVE FREEZING EXCEPT FOR AT ELEVATION... AND CURRENT RADAR EXTENT OF THE SYSTEM IS LIMITED. PUT ALL OF THAT TOGETHER AND THE BEST CHC IS THAT NO MEASURABLE SNOW MAKES IT EAST OF THE MTNS. THERE IS AROUND A 30 PERCENT CHC FOR A DUSTING FOR THE N TIER OF MD... AND AN EVEN SMALLER 10-20 PERCENT CHC OF A DUSTING SOUTH OF THAT. ONCE THE CLIPPER ROLLS THRU... SKIES CLEAR OUT AGAIN AND NW WINDS KICK UP AGAIN BRINGING COLD TEMPS AROUND 20 FOR MANY BY WED MORNING WITH WIND CHILLS BACK DOWN AROUND ZERO IN THE WESTERN MOUNTAINS AND IN THE TEENS AND SINGLE DIGITS FOR THE REST. IN THE WESTERN UPSLOPE AREAS OF W GRANT W MINERAL AND W ALLEGANY COUNTIES THERE WILL BE A SNOW ADV ISSUED FOR THIS AFTERNOON AND OVERNIGHT. 1 TO 3 INCHES WILL LIKELY PILE UP AGAIN AS SNOW SHOWERS RETURN. AVIATION /09Z-12Z/... VFR CONDITIONS EXPECTED THRU THE TAF PERIOD FOR THE MOST PART. MAY BRIEFLY TOUCH MVFR CONDTIONS WHEN THE CLIPPER ACTUALLY MOVES THRU IN THE AFTERNOON... BUT BETTER CHC THAT IT WILL REMAIN VFR. SW WINDS WILL FLIP TO NW AND BECOME GUSTY AGAIN THIS EVENING AND TONIGHT. SNOW SHOWERS IN THE MOUNTAINS WILL BE REFLECTED IN THE TWEBS. THERE IS A SLIGHT CHC OF A CONVECTIVE BAND OF SNOW SHOWERS DEVELOPING ALONG THE CLIPPER...BUT AGAIN A BETTER CHC THAT SNOW SHOWERS WILL NOT MAKE IT EAST OF THE MOUNTAINS. MARINE... AFTER THE CLIPPER LOW MOVES THRU AND STRENGTHENS A LITTLE BIT WINDS WILL KICK UP ONCE AGAIN AND A SMALL CRAFT ADVISORY IS IN PLACE FOR 9 PM TONIGHT THROUGH 10 AM WEDNESDAY. SMALL CRAFT ADVISORY CONDITIONS THIS WEEKEND IN THE WAKE OF THE LOW PRESSURE SYSTEM AFFECTING THE WATERS THURSDAY NIGHT. LONG TERM /WEDNESDAY THROUGH MONDAY/... BUSY MEDIUM RANGE FORECAST WITH A LOW PRESSURE SYSTEM MAKING ITS WAY FROM THE CENTRAL GULF COAST NORTHEAST ACROSS THE MID ATLANTIC STATES THURSDAY NIGHT. HIGH PRESSURE WILL PUSH THIS SYSTEM OUT TO SEA FOR THE WEEKEND...PROVIDING COOL AND DRY CONDITIONS FOR MOST LOCATIONS THROUGH THE END OF THE FORECAST PERIOD. THE EXCEPTION WILL BE CONTINUED CHANCES FOR UPSLOPE SHOWERS WEST OF THE ALLEGANY FRONT. MAIN FORECAST CHALLENGE IS WITH THE SOUTHERN STREAM LOW APPROACHING THURSDAY. MODELS CONTINUE THEIR INCONSISTENCIES WITH THIS SYSTEM FROM TIMING AND LOCATION TO PRECIPITATION TYPE. WHILE THE TRACK OF THE ACTUAL LOW IS STILL UNCERTAIN...BUT GUIDANCE COMES BACK IN LINE WITH THE LOW PLACED OFF THE NORTHERN MID ATLANTIC COAST FRIDAY MORNING AT 12Z. THE ECMWF IS THE FASTER MODEL WHILE THE NAM IS THE SLOWEST AND THE GFS IN BETWEEN. TOOK A BLEND OF THE THREE USING THE GFS. WHILE EARLIER RUNS BROUGHT PRECIPITATION IN FASTER...GUIDANCE HAS SINCE BACKED OFF. EXPECT PRECIPITATION TO SPREAD NORTHEAST ACROSS THE FORECAST AREA THURSDAY AFTERNOON...WITH HIGHEST POPS MOST LIKELY THURSDAY NIGHT. PRECIPITATION TYPES WITH THIS SYSTEM WILL BE INTERESTING TO WATCH OVER THE NEXT DAY OR TWO. WITH THE VARYING TRACKS OF THE LOW...TYPE FORECASTING HAS BEEN MORE OF A CHALLENGE. USING HPC GUIDANCE AND BUFKIT MODEL SOUNDINGS...A CHANGE OVER FROM SNOW TO FREEZING RAIN IS A POSSIBILITY ACROSS THE CENTRAL FORECAST AREA...AND SWITCHING FROM SNOW TO RAIN IN THE FAR NORTHEAST. HAVE ADDED THE MENTION OF SNOW AND FREEZING RAIN TO THE GRIDS FOR WASHINGTON DC WEST TO THE BLUE RIDGE AND SOUTH THROUGH THE SHENANDOAH VALLEY...WITH A RAIN AND SNOW MIX ACROSS BALTIMORE. CONFIDENCE WITH PRECIPITATION TYPE IS LOW GIVEN VARIANCE OF RECENT MODEL RUNS...SO THIS WILL MOST LIKELY CHANGE OVER THE NEXT 24 TO 48 HOURS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...SNOW ADVISORY FROM 1 PM THIS AFTERNOON TO 7 AM EST WEDNESDAY FOR MDZ501. VA...NONE. WV...SNOW ADVISORY FROM 1 PM THIS AFTERNOON TO 7 AM EST WEDNESDAY FOR WVZ501-503. MARINE...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 10 AM EST WEDNESDAY FOR ANZ530>537. && $$ PREV DISCUSSION...STRONG/SAR UPDATED SHORT TERM/AVIATION/MARINE...HTS md AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1035 PM EST TUE JAN 30 2007 .UPDATE... MAIN FCST CONCERN IS LOCATION/STRENGTH OF LES BANDS. RADAR INDICATED A PROMINENT WEST TO EAST LES BAND FROM JUST SOUTH OF STANNARD ROCK TO WHITEFHISH POINT. SIGNFICANT LOW LVL CONVERGENCE WAS EVIDENT WITH W OR SW WINDS FROM MARQUETTE TO GRAND MARAIS AND NW WINDS FROM THE KEWEENAW AND STANNARD ROCK. OVER THE WEST...SFC OBS SUGGEST LOW LVL CONV WAS FOCUSED BETWEEN ONTONAGON AND KCMX. 00Z TAMDAR SNDG SHOWED TEMPS TO NEAR -19C AT 850 MB (5K FT) INVERSION WHILE UPSTREAM KDLH SNDG SHOWED A LOWER INVERSION(AROUND 900 MB) AND A SIGNIFICANTLY DRIER PROFILE. MESO MODELS SHOWED SLIGHTLY DIFFERENT POSITION FOR BEST LOW LVL CONV AND LIKELY LOCATION FOR STRONGEST LES OVER THE WEST. THE NAM CONTINUED TO FOCUS LES BAND FARTHER NORTH...INTO HOUGHTON...THAN THE LAPS WRF-ARW (JUST N OF M-38) OR THE RUC13(SOUTH OF M-38). THE GOING FCST ADEQUATELY REFLECTS POTENTIAL FOR 3-6 INCH FROM ROCKLAND TO CALUMET. HOWEVER...ONLY MORE LOCALIZED HEAVIER AMOUNTS ARE EXPECTED...MOST LIKELY S OF HOUGHTON. RADAR TREND AND MESO MODELS STILL SUGGEST SIGNFICANT LES POTENTIAL ALONG THE LAKE SUPERIOR SHORE E OF GRAND MARAIS THAT EVENTUALLY WOULD SAG FARTHER S INTO ERN ALGER COUNTY AND NRN LUCE COUNTY BY DAYBREAK. AGAIN...THERE IS LITTLE NEED AT THIS POINT TO ALTER GOING FCST AS POTENTIAL REMAINS FOR LOCAL 4-8 INCH AMOUNTS BY DAYBREAK. && JLB .PREV DISCUSSION...ISSUED 325 PM EST TUE JAN 30 2007 ...ARCTIC AIR TO INVADE WEST AND CENTRAL UPPER MICHIGAN THIS WEEKEND... .SYNOPSIS... 20Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED UPPER TROUGHING COVERING MUCH OF SE CANADA INTO THE GREAT LAKES...WITH THE CENTER BEING A 498 DAM POLAR VORTEX OVER HUDSON BAY. ON THE WEST SIDE OF THE VORTEX WAS A SHRTWV OVER FAR NORTHERN ONTARIO... ACCOMPANIED BY A 90 KT JET STREAK NEAR THE TROPOPAUSE. THIS SHRTWV IS ALSO ASSOCIATED WITH A LOW PRESSURE TROUGH...WHICH EXTENDS FROM NE MANITOBA INTO NORTHERN ONTARIO JUST N OF PICKLE LAKE. ALTHOUGH 12Z SOUNDINGS FROM NEARBY CANADIAN RAOBS DO NOT INDICATE A LOT OF MOISTURE WITH THE SHRTWV...SURFACE OBS AND VISIBLE SATELLITE IMAGERY DOES SHOW A STRATUS DECK ALONG AND BEHIND THIS TROUGH...WITH OVERCAST CEILINGS BETWEEN 5000-8000 FT. EVEN A LITTLE LIGHT SNOW HAS BEEN REPORTED...WITH A 2 1/2 SM VISIBILITY RECENTLY AT PICKLE LAKE. 850MB TEMPS ARE STILL CHILLY NEAR THIS TROUGH...WITH THE PICKLE LAKE ONTARIO 12Z SOUNDING REPORTING AROUND -17C. CLOSER TO HOME...A 1018MB HIGH PRESSURE RIDGE AXIS IS BUILDING OVER UPPER MICHIGAN... WHICH EXTENDS WESTWARD TO A 1034MB HIGH CENTERED OVER NEBRASKA. THE COMBINATION OF DRIER AIR (SEE 12Z INL SOUNDING) AND DEVELOPING ANTICYCLONIC FLOW ASSOCIATED WITH THE SURFACE RIDGE HAS HELPED TO GREATLY DIMINISH THE LAKE EFFECT SNOW FROM WHAT OCCURRED LAST NIGHT. HOWEVER...WEAK RETURN FLOW ON THE BACK SIDE OF THE RIDGE AXIS HAS ALLOWED LAKE EFFECT TO RAPIDLY DEVELOP ON WESTERN LAKE SUPERIOR. FARTHER TO THE WEST...A STRONG SHRTWV CAN BE SEEN DIVING SOUTHWARD THROUGH SASKATCHEWAN ON THE EAST SIDE OF A VERY AMPLIFIED RIDGE WHEICH EXTENDS UP INTO ALASKA. ON THE NORTH SIDE OF THIS RIDGE OVER THE ARCTIC OCEAN IS YET A STRONGER SHRTWV...AND THIS IS THE ONE THAT WILL BRING THE ARCTIC AIR IN FOR THE WEEKEND. && .SHORT TERM (TONIGHT AND WED)... MAIN FORECAST CONCERN IS LES WITH APPROACHING SHRTWV. WINDS CONTINUING TO BACK TO THE WEST...ALONG WITH THE APPROACHING SHRTWV AND SURFACE TROUGHS...WILL SET UP AN INTERESTING SCENARIO FOR TONIGHT. AS TEMPERATURES COOL DOWN THIS EVENING IN THE INTERIOR AND OVER ONTARIO...LAND BREEZES ARE LIKELY TO SET UP. THESE LAND BREEZES WILL HELP TO FOCUS STRONG CONVERGENCE ALONG THE SURFACE TROUGH...WHICH IS PROGGED TO REACH THE KEWEENAW PENINSULA AND THE LAKE SUPERIOR SHORELINE NEAR GRAND MARAIS AROUND 03Z. THIS CONVERGENCE...COMBINED WITH PLENTY OF OVER-WATER INSTABILITY (AS NOTED WITH PICKLE LAKES RAOB) AND SYNOPTIC MOISTURE SHOULD HELP GENERATE SOME HEAVY LES...ESPECIALLY SINCE THE OMEGA INDUCED FROM THE LAKE EFFECT WILL INTERSECT A 50-75MB DEEP SNOW GROWTH LAYER PER MODEL SOUNDINGS. EXACTLY HOW STRONG THE LAND BREEZE IS WILL DICTATE HOW FAR SOUTH THE CONVERGENCE AND HEAVY SNOW GOES...PARTICULARLY IN THE WESTERN U.P. THE 13 KM RUC...WHICH HAS HAD A GOOD HANDLE ON LATEST LES EVENTS...SUGGESTS THE BAND WILL FOCUS IN THE AREA BETWEEN ROCKLAND AND BARAGA. HOWEVER THE NAM...REGIONAL CANADIAN AND LOCAL HIGH RESOLUTION WRF RUNS KEEP THE BAND FARTHER NORTH...ACROSS PAINESDALE AND HOUGHTON. THE LATEST 15Z AND 18Z RUC RUNS APPEAR TO BE FOLLOWING THE NAM SCENARIO TOO. SINCE ALL SOLUTIONS SEEM PLAUSIBLE...HAVE DECIDED TO FOLLOW A COMPROMISE. WHEREVER IT SETS UP...IT WILL LIKELY REMAIN NEARLY STATIONARY FOR 9 TO 12 HOURS BEFORE THE CONVERGENCE ZONE MOVES NORTHWARD...AND GIVEN GREAT SNOW GROWTH ON MODEL SOUNDINGS...DECIDED TO HOIST WARNINGS EARLIER FOR NE ONTONAGON AND NORTHERN HOUGHTON COUNTIES. ADVISORIES ARE POSTED FOR KEWEENAW AND SOUTHERN HOUGHTON FOR BOTH UNCERTAINTY REGARDING BAND PLACEMENT AND POSSIBLE OTHER BANDS THAT ARE AIDED BY UPSLOPE. KEWEENAW COUNTY WILL NEED TO BE WATCHED A LITTLE MORE TOMORROW AS THE CONVERGENCE ZONE MAY GET STUCK THERE. DECIDED NOT TO GO WITH A WARNING...THOUGH...AS THE CONVERGENCE WEAKENS DRAMATICALLY FROM THAT OBSERVED TONIGHT. FOR THE EASTERN CWA...UPGRADED THE WATCH EARLIER TO A WARNING AS MODELS ARE IN GOOD AGREEMENT HERE WITH THE CONVERGENCE AREA. LOCAL HIGH RESOLUTION WRF RUN SUGGESTS UP TO 0.60 OF QPF UNDER THIS CONVERGENCE...WHICH GIVEN RECENT SNOW TO WATER RATIOS WOULD SUGGEST UP TO 18 INCHES OF SNOW. DID NOT GO THIS HIGH AT THE PRESENT TIME...BUT IT WOULD NOT BE A SURPRISE IF AMOUNTS THAT HIGH OCCUR...ESPECIALLY GIVEN EXTRA CONVERGENCE HELP FROM LAND BREEZES OFF ONTARIO. AWAY FROM THE LES DURING THE SHORT TERM PERIOD...CONDITIONS LOOK FAIRLY QUIET. ALTHOUGH THE STRATUS DECK OVER ONTARIO IS EXPECTED TO MOVE OVER THE CWA THIS EVENING...MUCH OF THE SHRTWV FORCING WHICH HAS HELPED PRODUCE THE LIGHT SNOW AT PICKLE LAKE IS PROGGED TO MOVE OFF TO THE E. THEREFORE HAVE REMOVED ANY SLIGHT CHANCE POPS FOR SYNOPTIC SNOW. ALSO REMOVED POPS FOR SYNOPTIC SNOW ON WED SINCE MUCH OF THE CWA IS PROGGED TO BE IN WEAK SHRTWV RIDGING BETWEEN TONIGHTS SHRTWV AND THE SASKATCHEWAN SHRTWV TROUGH. GOING FORECAST TEMPERATURES THROUGH WED LOOK REASONABLE AND HAVE MADE VERY FEW CHANGES TO THEM. .LONG TERM (WED NIGHT THROUGH NEXT TUE)... ON WED NGT...SHRTWV TROF/DEEPER MSTR WL BE PUSHING TO THE E WED NGT...AND GUIDANCE SHOWS LLVL FLOW VEERING MORE W OVERNGT W-E IN ITS WAKE AND GRDLY BECMG MORE ACYC WITH APRCH OF SHRTWV RDGING/DNVA/ H85-5 QVECTOR DVGC. THESE EVENTS SHOULD CAUSE LES BANDS NEAR THE TIP OF THE KEWEENAW TO MIGRATE TO THE S IN LINE WITH GFS/NAM FCST SHARPER LLVL CNVGC. HOWEVER...SHIFTING WINDS/MORE TRANSIENT CNVGC/ NEGATIVE DYNAMICS MIGHT LIMIT SN ACCUMULATION WED NGT. WL GO WITH LIKELY POPS OVER THE W FM ONTONAGON COUNTY TO THE N. SINCE GUIDANCE SHOWS FOCUSED LLVL CNVGC REMAINING TO THE N OF THE ERN ZNS...WL GO WITH JUST CHC POPS NR LK SUP E OF P53. OTRW...ANY PTCHY -SN/ FLURRIES ACCOMPANYING SHRTWV WL TEND TO DIMINISH OVERNGT ONCE DEEPER MSTR/DYNAMICS EXIT TO THE E. PREFER LOWER GOING FCST MIN TEMPS WITH PROSPECT OF DRYING ALF LATE AS SHOWN ON GFS FCST SDNGS EVEN THOUGH BKN-OVC SC SHOULD LINGER UNDER DVLPG SUBSIDENCE INVRN. EXPECT A RELATIVELY QUIET DAY ON THU UNDER WEAK SHRTWV RDG DOWNSTREAM OF A DEEPENING TROF IN THE NRN PLAINS AND LLVL FLOW SLOWLY BACKING MORE SW. EVEN THOUGH QUITE A BIT OF SC WL LINGER UNDER MID LVL DRY AIR/SUBSIDENCE INVRN SHOWN ON GFS FCST SDNGS....WL RESTRICT MENTION OF POPS ON THU TO AREAS DOWNWIND OF LK SUP IN EXPECTED WSW FLOW. PREFER SOMEWHAT LOWER GFS MOS TEMPS GIVEN EXPECTED CLD COVER/H85 TEMPS -15C TO -17C OR SO. AS SHRTWV FM THE NRN PLAINS MOVES INTO THE UPR MS VALLEY BY 12Z FRI AND THEN INTO ERN LK SUP BY 00Z FRI ACCOMPANINED BY SOME FAIRLY HEALTHY DPVA/H85-5 QVECTOR CNVGC/12 HR H5 HGT FALLS APRCHG 80M... EXPECT A RELATIVELY WDSPRD SN TO DVLP...WITH THE HEAVIEST SN FALLING OVER THE NW HALF OF THE FA ON CYC SIDE OF H5 VORT TRACK WHERE LLVL NW FLOW WL OFFER THE OPPORTUNITY FOR SOME LK ENHANCEMENT AS H85 TEMPS TUMBLE IN THE AFTN AND GFS FCST SDNGS SHOW DEEP MSTR THRU THE TROP. DECIDED TO BUMP POPS UP TO LIKELY EVERYWHERE WITH CATEGORICAL POPS FM IWD-CMX-HURON MTNS ON FRI. LATER SHIFTS WL LIKELY NEED TO ISSUE HEADLINE FOR THIS EVENT EVEN THOUGH LATEST NCEP FCST SN AMTS JUST A FEW INCHES. BITTER COLD WL BE THE MAIN WX STORY THIS WEEKEND/EARLY NEXT WEEK IN PERSISENT HI AMPLITUDE NEGATIVE NAO/POSTIVE PNA DEEP UPR TROF CENTERED BTWN ERN PAC RDG NOSING INTO AK AND BLOCKING UPR HI IN THE N ATLANTIC OCEAN. ALTHOUGH THERE ARE SOME SLGT TIMING DIFFERENCES... 00Z>12Z MID RANGE GUIDANCE IN FAIRLY GOOD AGREEMENT WITH 0Z GFS REFCST ENSEMBLE MEAN DEPICTING SFC LO CROSSING LK SUP ON FRI (SEE ABV) IN ADVANCE OF INCOMING WAVE OF ARCTIC AIR. CORE OF ARCTIC COLD WITH H85 TEMPS IN THE -28C TO -32C RANGE FCST BY BOTH 06Z GFS/12Z ECMWF TO INVADE SAT AND PERSIST INTO TUE. GFS REFCST ENSEMBLE MEAN SHOWS AVERAGE H1000-5 THKNS ARND 488DM WITH H85 TEMPS FCST IN EXCESS OF 2 STANDARD DEVIATIONS BLO NORMAL. AS A COMPARISON TO RECENT COLD WAVES...H85 TEMPS IN THE EARLY FEB 1996 COLD WAVE WERE -30C TO -35C...SO THIS EVENT MAY END UP MARGINALLY WARMER THAN THE COLD OBSVD IN EARLY FEB 1996. GIVEN AGREEMENT AMONG OPS MODELS/ENSEMBLE MEAN...WL GO TOWARD THE LO END OF GFS MOS GUIDANCE FOR THE WEEKEND/EARLY NEXT WEEK... WITH SOME MIN TEMPS AOB -30F/MAX TEMPS REMAINING BLO 0F A GOOD BET FOR INTERIOR AREAS. ALTHOUGH LES WL BE ONGOING NR LK SUP WITH CORE OF COLD PASSING OVER LK SUP ESPECIALLY IN NW FLOW BELTS TO THE S OF LK INDUCED TROF NR LK SUP...SUCH FRIGID TEMPS WL NOT BE CONDUCIVE FOR FVRBL SN GROWTH. COORDINATED WITH GRB. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING 7 PM THIS EVENING TO 1 PM WED MIZ002-003 LAKE EFFECT SNOW WARNING 10 PM THIS EVENING TO 1 PM WED MIZ006-007 LAKE EFFECT SNOW ADVISORY 7 PM THIS EVENING TO 1 PM WED MIZ001 LAKE EFFECT SNOW ADVISORY 7 PM THIS EVENING TO 10 AM WED MIZ084 HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. && $$ AJ (SHORT TERM) KC (LONG TERM) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 325 PM EST TUE JAN 30 2007 ...ARCTIC AIR TO INVADE WEST AND CENTRAL UPPER MICHIGAN THIS WEEKEND... .SYNOPSIS... 20Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED UPPER TROUGHING COVERING MUCH OF SE CANADA INTO THE GREAT LAKES...WITH THE CENTER BEING A 498 DAM POLAR VORTEX OVER HUDSON BAY. ON THE WEST SIDE OF THE VORTEX WAS A SHRTWV OVER FAR NORTHERN ONTARIO... ACCOMPANIED BY A 90 KT JET STREAK NEAR THE TROPOPAUSE. THIS SHRTWV IS ALSO ASSOCIATED WITH A LOW PRESSURE TROUGH...WHICH EXTENDS FROM NE MANITOBA INTO NORTHERN ONTARIO JUST N OF PICKLE LAKE. ALTHOUGH 12Z SOUNDINGS FROM NEARBY CANADIAN RAOBS DO NOT INDICATE A LOT OF MOISTURE WITH THE SHRTWV...SURFACE OBS AND VISIBLE SATELLITE IMAGERY DOES SHOW A STRATUS DECK ALONG AND BEHIND THIS TROUGH...WITH OVERCAST CEILINGS BETWEEN 5000-8000 FT. EVEN A LITTLE LIGHT SNOW HAS BEEN REPORTED...WITH A 2 1/2 SM VISIBILITY RECENTLY AT PICKLE LAKE. 850MB TEMPS ARE STILL CHILLY NEAR THIS TROUGH...WITH THE PICKLE LAKE ONTARIO 12Z SOUNDING REPORTING AROUND -17C. CLOSER TO HOME...A 1018MB HIGH PRESSURE RIDGE AXIS IS BUILDING OVER UPPER MICHIGAN... WHICH EXTENDS WESTWARD TO A 1034MB HIGH CENTERED OVER NEBRASKA. THE COMBINATION OF DRIER AIR (SEE 12Z INL SOUNDING) AND DEVELOPING ANTICYCLONIC FLOW ASSOCIATED WITH THE SURFACE RIDGE HAS HELPED TO GREATLY DIMINISH THE LAKE EFFECT SNOW FROM WHAT OCCURRED LAST NIGHT. HOWEVER...WEAK RETURN FLOW ON THE BACK SIDE OF THE RIDGE AXIS HAS ALLOWED LAKE EFFECT TO RAPIDLY DEVELOP ON WESTERN LAKE SUPERIOR. FARTHER TO THE WEST...A STRONG SHRTWV CAN BE SEEN DIVING SOUTHWARD THROUGH SASKATCHEWAN ON THE EAST SIDE OF A VERY AMPLIFIED RIDGE WHEICH EXTENDS UP INTO ALASKA. ON THE NORTH SIDE OF THIS RIDGE OVER THE ARCTIC OCEAN IS YET A STRONGER SHRTWV...AND THIS IS THE ONE THAT WILL BRING THE ARCTIC AIR IN FOR THE WEEKEND. && .SHORT TERM (TONIGHT AND WED)... MAIN FORECAST CONCERN IS LES WITH APPROACHING SHRTWV. WINDS CONTINUING TO BACK TO THE WEST...ALONG WITH THE APPROACHING SHRTWV AND SURFACE TROUGHS...WILL SET UP AN INTERESTING SCENARIO FOR TONIGHT. AS TEMPERATURES COOL DOWN THIS EVENING IN THE INTERIOR AND OVER ONTARIO...LAND BREEZES ARE LIKELY TO SET UP. THESE LAND BREEZES WILL HELP TO FOCUS STRONG CONVERGENCE ALONG THE SURFACE TROUGH...WHICH IS PROGGED TO REACH THE KEWEENAW PENINSULA AND THE LAKE SUPERIOR SHORELINE NEAR GRAND MARAIS AROUND 03Z. THIS CONVERGENCE...COMBINED WITH PLENTY OF OVER-WATER INSTABILITY (AS NOTED WITH PICKLE LAKES RAOB) AND SYNOPTIC MOISTURE SHOULD HELP GENERATE SOME HEAVY LES...ESPECIALLY SINCE THE OMEGA INDUCED FROM THE LAKE EFFECT WILL INTERSECT A 50-75MB DEEP SNOW GROWTH LAYER PER MODEL SOUNDINGS. EXACTLY HOW STRONG THE LAND BREEZE IS WILL DICTATE HOW FAR SOUTH THE CONVERGENCE AND HEAVY SNOW GOES...PARTICULARLY IN THE WESTERN U.P. THE 13 KM RUC...WHICH HAS HAD A GOOD HANDLE ON LATEST LES EVENTS...SUGGESTS THE BAND WILL FOCUS IN THE AREA BETWEEN ROCKLAND AND BARAGA. HOWEVER THE NAM...REGIONAL CANADIAN AND LOCAL HIGH RESOLUTION WRF RUNS KEEP THE BAND FARTHER NORTH...ACROSS PAINESDALE AND HOUGHTON. THE LATEST 15Z AND 18Z RUC RUNS APPEAR TO BE FOLLOWING THE NAM SCENARIO TOO. SINCE ALL SOLUTIONS SEEM PLAUSIBLE...HAVE DECIDED TO FOLLOW A COMPROMISE. WHEREVER IT SETS UP...IT WILL LIKELY REMAIN NEARLY STATIONARY FOR 9 TO 12 HOURS BEFORE THE CONVERGENCE ZONE MOVES NORTHWARD...AND GIVEN GREAT SNOW GROWTH ON MODEL SOUNDINGS...DECIDED TO HOIST WARNINGS EARLIER FOR NE ONTONAGON AND NORTHERN HOUGHTON COUNTIES. ADVISORIES ARE POSTED FOR KEWEENAW AND SOUTHERN HOUGHTON FOR BOTH UNCERTAINTY REGARDING BAND PLACEMENT AND POSSIBLE OTHER BANDS THAT ARE AIDED BY UPSLOPE. KEWEENAW COUNTY WILL NEED TO BE WATCHED A LITTLE MORE TOMORROW AS THE CONVERGENCE ZONE MAY GET STUCK THERE. DECIDED NOT TO GO WITH A WARNING...THOUGH...AS THE CONVERGENCE WEAKENS DRAMATICALLY FROM THAT OBSERVED TONIGHT. FOR THE EASTERN CWA...UPGRADED THE WATCH EARLIER TO A WARNING AS MODELS ARE IN GOOD AGREEMENT HERE WITH THE CONVERGENCE AREA. LOCAL HIGH RESOLUTION WRF RUN SUGGESTS UP TO 0.60 OF QPF UNDER THIS CONVERGENCE...WHICH GIVEN RECENT SNOW TO WATER RATIOS WOULD SUGGEST UP TO 18 INCHES OF SNOW. DID NOT GO THIS HIGH AT THE PRESENT TIME...BUT IT WOULD NOT BE A SURPRISE IF AMOUNTS THAT HIGH OCCUR...ESPECIALLY GIVEN EXTRA CONVERGENCE HELP FROM LAND BREEZES OFF ONTARIO. AWAY FROM THE LES DURING THE SHORT TERM PERIOD...CONDITIONS LOOK FAIRLY QUIET. ALTHOUGH THE STRATUS DECK OVER ONTARIO IS EXPECTED TO MOVE OVER THE CWA THIS EVENING...MUCH OF THE SHRTWV FORCING WHICH HAS HELPED PRODUCE THE LIGHT SNOW AT PICKLE LAKE IS PROGGED TO MOVE OFF TO THE E. THEREFORE HAVE REMOVED ANY SLIGHT CHANCE POPS FOR SYNOPTIC SNOW. ALSO REMOVED POPS FOR SYNOPTIC SNOW ON WED SINCE MUCH OF THE CWA IS PROGGED TO BE IN WEAK SHRTWV RIDGING BETWEEN TONIGHTS SHRTWV AND THE SASKATCHEWAN SHRTWV TROUGH. GOING FORECAST TEMPERATURES THROUGH WED LOOK REASONABLE AND HAVE MADE VERY FEW CHANGES TO THEM. .LONG TERM (WED NIGHT THROUGH NEXT TUE)... ON WED NGT...SHRTWV TROF/DEEPER MSTR WL BE PUSHING TO THE E WED NGT...AND GUIDANCE SHOWS LLVL FLOW VEERING MORE W OVERNGT W-E IN ITS WAKE AND GRDLY BECMG MORE ACYC WITH APRCH OF SHRTWV RDGING/DNVA/ H85-5 QVECTOR DVGC. THESE EVENTS SHOULD CAUSE LES BANDS NEAR THE TIP OF THE KEWEENAW TO MIGRATE TO THE S IN LINE WITH GFS/NAM FCST SHARPER LLVL CNVGC. HOWEVER...SHIFTING WINDS/MORE TRANSIENT CNVGC/ NEGATIVE DYNAMICS MIGHT LIMIT SN ACCUMULATION WED NGT. WL GO WITH LIKELY POPS OVER THE W FM ONTONAGON COUNTY TO THE N. SINCE GUIDANCE SHOWS FOCUSED LLVL CNVGC REMAINING TO THE N OF THE ERN ZNS...WL GO WITH JUST CHC POPS NR LK SUP E OF P53. OTRW...ANY PTCHY -SN/ FLURRIES ACCOMPANYING SHRTWV WL TEND TO DIMINISH OVERNGT ONCE DEEPER MSTR/DYNAMICS EXIT TO THE E. PREFER LOWER GOING FCST MIN TEMPS WITH PROSPECT OF DRYING ALF LATE AS SHOWN ON GFS FCST SDNGS EVEN THOUGH BKN-OVC SC SHOULD LINGER UNDER DVLPG SUBSIDENCE INVRN. EXPECT A RELATIVELY QUIET DAY ON THU UNDER WEAK SHRTWV RDG DOWNSTREAM OF A DEEPENING TROF IN THE NRN PLAINS AND LLVL FLOW SLOWLY BACKING MORE SW. EVEN THOUGH QUITE A BIT OF SC WL LINGER UNDER MID LVL DRY AIR/SUBSIDENCE INVRN SHOWN ON GFS FCST SDNGS....WL RESTRICT MENTION OF POPS ON THU TO AREAS DOWNWIND OF LK SUP IN EXPECTED WSW FLOW. PREFER SOMEWHAT LOWER GFS MOS TEMPS GIVEN EXPECTED CLD COVER/H85 TEMPS -15C TO -17C OR SO. AS SHRTWV FM THE NRN PLAINS MOVES INTO THE UPR MS VALLEY BY 12Z FRI AND THEN INTO ERN LK SUP BY 00Z FRI ACCOMPANINED BY SOME FAIRLY HEALTHY DPVA/H85-5 QVECTOR CNVGC/12 HR H5 HGT FALLS APRCHG 80M... EXPECT A RELATIVELY WDSPRD SN TO DVLP...WITH THE HEAVIEST SN FALLING OVER THE NW HALF OF THE FA ON CYC SIDE OF H5 VORT TRACK WHERE LLVL NW FLOW WL OFFER THE OPPORTUNITY FOR SOME LK ENHANCEMENT AS H85 TEMPS TUMBLE IN THE AFTN AND GFS FCST SDNGS SHOW DEEP MSTR THRU THE TROP. DECIDED TO BUMP POPS UP TO LIKELY EVERYWHERE WITH CATEGORICAL POPS FM IWD-CMX-HURON MTNS ON FRI. LATER SHIFTS WL LIKELY NEED TO ISSUE HEADLINE FOR THIS EVENT EVEN THOUGH LATEST NCEP FCST SN AMTS JUST A FEW INCHES. BITTER COLD WL BE THE MAIN WX STORY THIS WEEKEND/EARLY NEXT WEEK IN PERSISENT HI AMPLITUDE NEGATIVE NAO/POSTIVE PNA DEEP UPR TROF CENTERED BTWN ERN PAC RDG NOSING INTO AK AND BLOCKING UPR HI IN THE N ATLANTIC OCEAN. ALTHOUGH THERE ARE SOME SLGT TIMING DIFFERENCES... 00Z>12Z MID RANGE GUIDANCE IN FAIRLY GOOD AGREEMENT WITH 0Z GFS REFCST ENSEMBLE MEAN DEPICTING SFC LO CROSSING LK SUP ON FRI (SEE ABV) IN ADVANCE OF INCOMING WAVE OF ARCTIC AIR. CORE OF ARCTIC COLD WITH H85 TEMPS IN THE -28C TO -32C RANGE FCST BY BOTH 06Z GFS/12Z ECMWF TO INVADE SAT AND PERSIST INTO TUE. GFS REFCST ENSEMBLE MEAN SHOWS AVERAGE H1000-5 THKNS ARND 488DM WITH H85 TEMPS FCST IN EXCESS OF 2 STANDARD DEVIATIONS BLO NORMAL. AS A COMPARISON TO RECENT COLD WAVES...H85 TEMPS IN THE EARLY FEB 1996 COLD WAVE WERE -30C TO -35C...SO THIS EVENT MAY END UP MARGINALLY WARMER THAN THE COLD OBSVD IN EARLY FEB 1996. GIVEN AGREEMENT AMONG OPS MODELS/ENSEMBLE MEAN...WL GO TOWARD THE LO END OF GFS MOS GUIDANCE FOR THE WEEKEND/EARLY NEXT WEEK... WITH SOME MIN TEMPS AOB -30F/MAX TEMPS REMAINING BLO 0F A GOOD BET FOR INTERIOR AREAS. ALTHOUGH LES WL BE ONGOING NR LK SUP WITH CORE OF COLD PASSING OVER LK SUP ESPECIALLY IN NW FLOW BELTS TO THE S OF LK INDUCED TROF NR LK SUP...SUCH FRIGID TEMPS WL NOT BE CONDUCIVE FOR FVRBL SN GROWTH. COORDINATED WITH GRB. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING 7 PM THIS EVENING TO 1 PM WED MIZ002-003 LAKE EFFECT SNOW WARNING 10 PM THIS EVENING TO 1 PM WED MIZ006-007 LAKE EFFECT SNOW ADVISORY 7 PM THIS EVENING TO 1 PM WED MIZ001 LAKE EFFECT SNOW ADVISORY 7 PM THIS EVENING TO 10 AM WED MIZ084 HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. && $$ AJ (SHORT TERM) KC (LONG TERM) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1207 PM EST TUE JAN 30 2007 .SYNOPSIS... 16Z WATER VAPOR LOOP...RUC 500MB HEIGHT ANALYSIS AND 12Z RAOBS SHOWED UPPER TROUGHING COVERING MUCH OF SE CANADA INTO THE GREAT LAKES...WITH THE CENTER BEING A 498 DAM POLAR VORTEX OVER HUDSON BAY. ON THE WEST SIDE OF THE VORTEX WAS A SHRTWV OVER FAR NORTHERN ONTARIO...ACCOMPANIED BY A 90 KT JET STREAK NEAR THE TROPOPAUSE. THIS SHRTWV IS ALSO ASSOCIATED WITH A LOW PRESSURE TROUGH...WHICH EXTENDS FROM NE MANITOBA INTO NORTHERN ONTARIO JUST N OF PICKLE LAKE. ALTHOUGH 12Z SOUNDINGS FROM NEARBY CANADIAN RAOBS DO NOT INDICATE A LOT OF MOISTURE WITH THE SHRTWV...SURFACE OBS AND VISIBLE SATELLITE IMAGERY DOES SHOW A STRATUS DECK ALONG AND BEHIND THIS TROUGH...WITH OVERCAST CEILINGS BETWEEN 5000-8000 FT. 850MB TEMPS ARE STILL CHILLY NEAR THIS TROUGH...WITH THE PICKLE LAKE ONTARIO SOUNDING REPORTING AROUND -17C. CLOSER TO HOME...A 1018MB HIGH PRESSURE RIDGE AXIS IS BUILDING INTO UPPER MICHIGAN FROM LAKE SUPERIOR...WHICH EXTENDS OFF A 1034MB HIGH CENTERED OVER NEBRASKA. THE COMBINATION OF DRIER AIR (SEE 12Z INL SOUNDING) AND DEVELOPING ANTICYCLONIC FLOW ASSOCIATED WITH THE SURFACE RIDGE HAS HELPED TO GREATLY DIMINISH THE LAKE EFFECT SNOW FROM WHAT OCCURRED LAST NIGHT. IN FACT...ALMOST ALL OF WESTERN LAKE SUPERIOR IS CLEAR WITH BANDS ONLY EXTENDING OUT ABOUT 25 MILES OFFSHORE. NONETHELESS...WITH THE GREATER FETCH LENGTH OF NORTHWEST WINDS ON EASTERN LAKE SUPERIOR TO HELP WITH MOISTENING... SOME BANDS STILL CONTAIN 24-28DBZ REFLECTIVITIES ON THE CURRENT RADAR LOOP. && .UPDATE... MAIN UPDATE CONCERN IS DEVELOPING LES TONIGHT FOR THIS AFTERNOON...WIND FLOW SHOULD CONTINUE TO BACK TOWARDS THE WEST AS BOTH THE SHRTWV AND SURFACE TROUGH OVER NORTHERN ONTARIO...AND THE HIGH PRESSURE RIDGE OVER LAKE SUPERIOR...DRIFT SOUTH. THIS SHOULD CAUSE THE BANDS OVER THE EASTERN CWA TO CONTINUE MOVING EASTWARD...THEN LIFT OUT OVER LAKE SUPERIOR LATE WHEN THE WIND IS PROGGED TO TURN DUE WEST. GOING FORECAST HAS THE SCENARIO HANDLED WELL AND ONLY A FEW MINOR TWEAKS WERE MADE TO THE SNOW COVERAGE AREA BASED ON RADAR TRENDS. THE WIND SWITCHING TO THE WEST...ALONG WITH THE APPROACHING SHRTWV AND SURFACE TROUGHS...SETS UP AN INTERESTING SCENARIO FOR TONIGHT. AS TEMPERATURES COOL DOWN THIS EVENING IN THE INTERIOR AND OVER ONTARIO...LAND BREEZES ARE LIKELY TO SET UP. THESE LAND BREEZES WILL HELP TO FOCUS STRONG CONVERGENCE ALONG THE SURFACE TROUGH...WHICH IS PROGGED TO REACH THE KEWEENAW PENINSULA AND THE LAKE SUPERIOR SHORELINE NEAR GRAND MARAIS AROUND 03Z. THIS CONVERGENCE...COMBINED WITH PLENTY OF OVER-WATER INSTABILITY (AS NOTED WITH PICKLE LAKES RAOB) AND SYNOPTIC MOISTURE SHOULD HELP GENERATE SOME HEAVY LES...ESPECIALLY SINCE THE OMEGA INDUCED FROM THE LAKE EFFECT WILL INTERSECT A 50-75MB DEEP SNOW GROWTH LAYER PER MODEL SOUNDINGS. EXACTLY HOW STRONG THE LAND BREEZE IS WILL DICTATE HOW FAR SOUTH THE CONVERGENCE AND HEAVY SNOW GOES...PARTICULARLY IN THE WESTERN U.P. THE 13 KM RUC...WHICH HAS HAD A GOOD HANDLE ON LATEST LES EVENTS...SUGGESTS THE BAND WILL FOCUS IN THE AREA BETWEEN ROCKLAND AND BARAGA. HOWEVER THE NAM AND LOCAL HIGH RESOLUTION WRF RUNS KEEP THE BAND FARTHER NORTH...ACROSS PAINESDALE AND HOUGHTON. THE LATEST 15Z RUC APPEARS TO BE FOLLOWING THE NAM SCENARIO TOO. SINCE ALL SOLUTIONS SEEM PLAUSIBLE...HAVE DECIDED TO FOLLOW A COMPROMISE. WHEREVER IT SETS UP...IT WILL LIKELY REMAIN NEARLY STATIONARY FOR 9 TO 12 HOURS BEFORE THE CONVERGENCE ZONE MOVES NORTHWARD...AND GIVEN GREAT SNOW GROWTH ON MODEL SOUNDINGS...DECIDED TO HOIST WARNINGS FOR NE ONTONAGON AND NORTHERN HOUGHTON COUNTIES. ADVISORIES ARE POSTED FOR KEWEENAW AND SOUTHERN HOUGHTON FOR BOTH UNCERTAINTY REGARDING BAND PLACEMENT AND POSSIBLE OTHER BANDS THAT ARE AIDED BY UPSLOPE. FOR THE EASTERN CWA...UPGRADED THE WATCH TO A WARNING AS MODELS ARE IN GOOD AGREEMENT HERE WITH THE CONVERGENCE AREA. LOCAL HIGH RESOLUTION WRF RUN SUGGESTS UP TO 0.60 OF QPF UNDER THIS CONVERGENCE...WHICH GIVEN RECENT SNOW TO WATER RATIOS WOULD SUGGEST UP TO 18 INCHES OF SNOW. DID NOT GO THIS HIGH AT THE PRESENT TIME...BUT IT WOULD NOT BE A SURPRISE IF AMOUNTS THAT HIGH OCCUR...ESPECIALLY GIVEN EXTRA CONVERGENCE HELP FROM LAND BREEZES OFF ONTARIO. .PREV DISCUSSION... LARGE SCALE SHOWS RIDGE OVER PACIFIC COAST INTO WESTERN CANADA AND ALASKA WHILE TROUGHING DOMINATES EASTERN CANADA INTO GREAT LAKES. THIS PATTERN WILL STAY AROUND FOR FORSEEABLE FUTURE. TROUGH ONLY DEEPENS LATE THIS WEEK INTO THE WEEKEND AND MOST LIKELY STAYING THAT WAY UNTIL EARLY NEXT WEEK. VERY COLD AIR WILL DECEND INTO MUCH OF THE CONUS...INCLUDING THE UPR GREAT LAKES REGION. SHORTWAVE THAT HAS PRODUCED STEADY LIGHT SNOW OVR MAINLY SOUTH CWA SINCE YDY AFTN IS MOVING INTO N LWR MI. SHORTWAVE AND DEEP MOISTURE WITH IT ALLOWED LK EFFECT SNOW SHOWERS TO INTENSIFY TREMENDOUSLY SINCE LATE LAST EVENING. HOWEVER...BANDS OF MOST INTENSE SNOW ARE ISOLATED. ONE BAND WAS AFFECTING SW SCHOOLCRAFT COUNTY FOR MUCH OF NIGHT. NOTHING HEARD FM THIS AREA YET...BUT WITH ECHOES PINGING 12KFT ON MQT RADAR OUT OVR N LK MI STAYING STATIONARY OVR SAME AREA FOR 5 HOURS OR SO SUGGESTS THAT AMOUNTS OF A FOOT WOULD NOT BE OUT OF QUESTION. THAT AREA OF ENHANCED SNOW IS BEGINNING TO SHIFT OFFSHORE AS WINDS JUST OFF SFC ARE INCREASING FM NORTH. MEANWHILE...STRONG SNOW BAND OVR LAKE SUPERIOR...THAT PRODUCED 6 INCHES OF SNOW LAST EVENING AT COPPER HARBOR PER LOCAL MEDIA REPORT...MIGRATED SOUTH AND HIT THE HIGHER TERRAIN OF NCNTRL UPR MI WITHIN THE LAST HOUR. BAND WAS PRETTY NARROW...BUT VERY INTENSE...DROPPING 4 INCHES OF SNOW IN ONE HOUR AT THE NWS OFFICE IN NEGAUNEE TOWNSHIP. FORTUNATELY...BAND IS TRANSITORY AND IS SHIFTING STEADILY INLAND. OPTED TO COVER QUICK MOVING BAND WITH SHORT TERM FORECASTS INSTEAD OF AN ADVISORY. EXPECT HEAVIEST SNOW...AIDED BY SYNOPTIC SUPPORT...TO DIMINISH BY MID MORNING IF NOT SOONER. ONLY REAL CHANGE TO PREV GRIDS FOR TODAY WAS TO KEEP LIKELY POPS OVR NE CWA INTO THE AFTN THOUGH SNOW INTENSITY SHOULD GREATLY DIMINISH BY THEN. TURNING TO TONIGHT. SHORTWAVE CURRENTLY NEAR CHURCHILL MANITOBA TRUCKS SSE AND REACHES NE LK SUPERIOR BY LATE TONIGHT. BRIEF PERIOD OF SYNOPTIC UPWARD MOTION AND DEEPER MOISTURE TO 10KFT WILL SPIKE LES AGAIN. GFS APPEARED TOO WEST WITH BLYR WINDS CONSIDERING CLOSENESS OF TROUGH...SO FOLLOWED NAM/RUC13/CAN GEM WITH IDEA OF NW WINDS DEVELOPING ON N HALF OF LK SUPERIOR TOWARD WHITEFISH BAY AND MORE W WINDS REMAINING ON W HALF OF LK SUPERIOR OVR KEWEENAW. THIS RESULTS IN A QUITE STRONG AREA OF CONVERGENCE DEVELOPING OVER FAR NE CWA TOWARD WHITEFISH POINT IN APX CWA. ANY DOMINANT BAND STREAMING INTO THIS AREA WILL ALSO HAVE ADDED BENEFIT OF MAXIMUM OVER WATER FETCH OVR THE STILL OPEN WATERS OF LK SUPERIOR. ONE OR TWO BANDS OF HEAVY SNOW SEEM PROBABLE IN THESE AREAS WITH SNOWFALL RATES SIMILAR TO THOSE SEEN TONIGHT. ALTHOUGH THE AREA IS RELATIVELY SMALL...POTENTIAL FOR LARGE AMOUNTS OF LES ARE THERE. SO...COORD WITH APX AND ISSUED A LK EFFECT SNOW WATCH FOR ALGER AND LUCE COUNTIES TONIGHT INTO WED FOR AREAS MOSTLY EAST OF GRAND MARAIS. FARTHER WEST OVER KEWEENAW...DID NOT GO WITH WATCH DUE TO THAT AREA BEING FARTHER DISPLACED FM SYNOPIC LIFT/MOISTURE AND A SHORTER OVER WATER FETCH. IF CONVERGENCE STRENGTHENS IN VCNTY OF APOSTLE ISLANDS (AS GFS INDICATES) THEN HEAVY SNOW COULD AFFECT PORTIONS OF KEWEENAW PENINSULA AS WELL. JUST HAVE ADVY AMOUNTS IN GRIDS ATTM. WINDS BACKING TO WSW SHOULD PUSH MOST OF HEAVY SNOW OFFSHORE OF ALGER/LUCE BY LATE MORNING ON WED...BUT SNOW SHOWERS WILL CONTINUE ON THE KEWEENAW. ONLY MADE MINOR CHANGES TO WED NIGHT THROUGH FRI FORECAST PERIODS. SOME LIGHT OVERRUNNING SNOW SEEMS POSSIBLE THU-THU NIGHT AHEAD OF PRIMARY SHORTWAVE THAT BEGINS TO BRING IN BITTER COLD AIR LATE FRI. SOME CONCERN THAT FRI AFTN-FRI EVENING PERIOD MAY BE QUITE HAZARDOUS DUE TO A PERIOD OF HEAVY SNOW...INCREASING WINDS...BLOWING SNOW... REDUCED VISIBILITIES. NOT TO MENTION...TUMBLING TEMPERATURES AND NO DOUBT WIND CHILL ISSUES. LOWERED TEMPS IN FRI NIGHT-SAT PERIODS FOR WEST HALF INTERIOR. WINDS BY LATE FRI NIGHT ARE MOSTLY FM WEST WHICH WILL LEAD TO MOSTLY OVER LAND TRAJECTORIES...LIMITING LAKE SUPERIOR MODERATION. THIS SHOULD ALLOW EFFICIENT TRANSPORT OF BITTER COLD AIR BANKED TO THE WEST AND NORTH INTO THE UPR LAKES. MEX GUIDANCE FOR FRI NIGHT SHOWED -10F TO -15F INLAND INTERIOR WHICH SEEMED FEASIBLE AND THAT WOULD LIKELY MEAN SOME LOCALES SAT WILL NOT HIT ZERO INLAND. IN FACT...LATEST GFS...WHICH AGREES WITH THE ECMWF...SHOWS TEMPS AT KIWD REMAINING BLO ZERO FM FRI NIGHT THROUGH MON. WILL CONTINUE TO HIGHLIGHT THE UPCOMING COLD IN HWO. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING 7 PM THIS EVENING TO 1 PM WED MIZ002-003 LAKE EFFECT SNOW WARNING 10 PM THIS EVENING TO 1 PM WED MIZ006-007 LAKE EFFECT SNOW ADVISORY 7 PM THIS EVENING TO 1 PM WED MIZ001 LAKE EFFECT SNOW ADVISORY 7 PM THIS EVENING TO 10 AM WED MIZ084 HEAVY FREEZING SPRAY WARNING EAST 1/2 LAKE SUPERIOR. && $$ AJ (UPDATE) JLA (PREV DISCUSSION) mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 940 PM EST MON JAN 29 2007 .UPDATE... RADAR INDICATED A PROMINENT LES BAND FROM THE LEELANAU PENINSULA TO SE UPPER MI. MESO-LOW CHARACTER TO THE BAND INTO THE AREA FROM KESC-KISQ WILL ENHANCE SNOWFALL RATES IN AN ENVIRONMENT ALREADY VERY FAVORABLE FOR SNOW GROWTH. 00Z AREA TAMDAR SNDGS SHOWED 850 MB TEMPS NEAR -17C WITH MOIST PROFILE OR NO INVERSION TO 700 MB(KPLN). THE 00Z NAM WAS CATCHING ON TO THIS FEATURE WHILE THE 18Z RUC13 HAD BEST GRASP OF THE LES SCENARIO. THE SHRTWV OVER NE WI IS EXPECTED TO SAG SE HELPING TO DRAG THE ASSOCIATED SFC LOW ALONG. THIS SHOULD RESULT IN A STRONG ENOUGH NRLY FLOW TO PUSH THE BAND OUT OF THE CWA BY 06Z-09Z. GIVEN POTENTIAL FOR 2-3 INCH SNOWFALL RATES WITH THE BAND(PER REPORT NEAR PT AUX BARQUES)...EXPECT LCL AMOUNTS INTO THE 4-8 INCH RANGE. SO...LES WARNING WAS POSTED FOR DELTA-SCHOOLCRAFT COUNTIES. FARTHER NORTH...LES WAS ALSO INCREASING JUST OFFSHORE FROM MARQUETTE AND WERE MOVING INLAND AS NE WINDS GRADUALLY INCREASE. THE RUC13 ALSO SUGGESTS THAT THE BEST LOW LVL CONV WILL QUICKLY SHIFT FORM KP59-STANNARD ROCK VCNTY SOUTHWARD WITH THE POTENTIAL FOR MORE SIGNIFICANT LES INTO MARQUETTE COUNTY. HOWEVER...CONFIDENCE IN THIS SCENARIO IS MORE LIMITED...GIVEN UNORGANIZED LOOK OF THE LES ON RADAR. SO...WILL ONLY MODERATELY BOOST GOING SNOWFALL AMOUNT FCST INTO THIS AREA. && JLB .PREV DISCUSSION...ISSUED 346 PM EST MON JAN 29 2007. ...COLDEST AIR OF THE SEASON TO MOVE INTO WEST AND CENTRAL UPPER MICHIGAN ON FRI... .SYNOPSIS... WATER VAPOR LOOP AND UPR AIR ANALYSIS SHOWS A HIGH AMPLITUDE RDG OVER THE ERN PAC AND NW NOAM WHILE DOWNSTREAM A BROAD TROF IS NOTED MUCH OF CANADA EXTENDING INTO GREAT LAKES AND NE U.S. THIS HIGH AMPLITUDE PATTERN NOT EXPECTED TO CHANGE MUCH THIS WEEK WHICH WILL ALLOW FOR POLAR VORTEX TO WORK ITS WAY SOUTHWARD INTO THE UPR GREAT LAKES BY THE WEEKEND. IN THE SHORT TERM...A SHORTWAVE/CLIPPER SYSTEM DIVING JUST TO OUR S HAS BROUGHT LIGHT SNOW TODAY TO MUCH OF WI AND SOME FLURRIES TO SW UPR MI. WINDS COMING AROUND TO THE N-NE THIS EVENING BEHIND CLIPPER SYSTEM WILL BRING SOME LES BACK ONSHORE TONIGHT INTO TUE. && .SHORT TERM (TONIGHT AND TUE)... THE MAIN CONCERN IS LES FOR TONIGHT INTO TUE. SFC/MARINE OBS SHOWS WINDS ALREADY STARTING TO COME AROUND TO NE OVER WRN LAKE SUPERIOR IN LINE WITH FCST OF RUC AND LOCAL MESOSCALE MODELS. MID-LAKE LES CONVERGENCE BAND OVER LAKE SUPERIOR EXPECTED TO COME ONSHORE THIS EVENING INTO WRN AND NCNTRL COUNTIES AS WINDS SHIFT TO N-NE BEHIND CLIPPER SYSTEM NOW DIVING S. EXPECT A BURST OF HEAVIER SNOW AS CONVERGENCE BAND COMES THROUGH AND THEN LOOK FOR SOME WIND-PARALLEL BANDS SETTING UP BEHIND IT INTO TUE. WEAK ENHANCEMENT THIS EVENING FROM MID-LVL TROF PASSAGE COULD BOOST SNOW AMTS SOME...BUT SHIFTING WINDS WILL NOT FOCUS HEAVY BANDS OVER ANY ONE AREA FOR TOO LONG. BEST CONVERGENCE WITH N-NE FLOW WOULD TEND TO FAVOR MQT COUNTY WHERE MESOSCALE MODEL QPF AROUND .10-.15 INCH COULD BRING TOTAL ACCUMULATIONS UP TO 4 INCHES AT SOME HIGHER TERRAIN LOCATIONS TONIGHT INTO TUE MORNING. SOME LOCATIONS IN GOGEBIC AND ONTONAGON COUNTIES COULD SEE UP TO 3 INCHES. ELSEWHERE ACROSS THE NRN TIER COUNTY...GENERALLY EXPECT 1-2". DID BUMP POPS TO CATEGORICAL FOR WEST AND NCNTRL COUNTIES TONIGHT WITH GOOD CYCLONIC FLOW AND POTENTIAL ENHANCEMENT FROM MID-LVL TROF. LOOKS LIKE LES SHOULD TAPER OFF OR END QUICKLY FOR MOST LOCATIONS BY MIDDAY TUE AS FLOW BECOMES ANTICYCLONIC AND BACKS MORE WRLY WITH BUILDING SFC RDG FROM THE NRN PLAINS. LEFT HIGHER POPS OVER ERN COUNTIES DUE TO LONGER FETCH ACROSS LAKE SUPERIOR IN NW TO W FLOW. .LONG TERM (TUE NIGHT THROUGH MON)... TUE NIGHT...MODELS SHOW A SHRTWV OVER THE NE PORTION OF NUNAVUT MOVING SSE THROUGH THE FLOW ALOFT...MOVING ACROSS NORTHERN ONTARIO DURING THIS TIME PERIOD. THE NAM BRINGS THIS SHRTWV MUCH CLOSER TO THE CWA THAN ALL THE OTHER MODELS (NEAR WAWA BY 06Z)...BUT BELIEVE THIS IS TOO CLOSE GIVEN THAT HEIGHTS ARE PROGGED TO RISE ACROSS THE UPPER MIDWEST AHEAD OF A TROUGH DIGGING INTO MONTANA. THEREFORE WILL FOLLOW THE GFS/REGIONAL CANADIAN AND OUR LOCAL WRF MODELS...WHICH KEEP THE SHRTWV FARTHER TO THE NE. BASICALLY...AS THIS SHRTWV MOVES DOWN...VERY WEAK ISENTROPIC ASCENT AND DPVA HELP TO PRODUCE A MID CLOUD DECK WHICH MOVES OVER THE CWA. AT THE LOW LEVELS...WITH A SURFACE RIDGE TRYING TO BUILD IN FROM THE WEST AND A WEAK TROUGH MOVING S ASSOCIATED WITH THE SHRTWV OVER LAKE SUPERIOR...A CONVERGENT LAKE EFFECT BAND LOOKS LIKELY...AIDED BY LAND BREEZES. RIGHT NOW THE BEST CONVERGENCE IS FOCUSED IN THE NORTHERN PART OF LUCE COUNTY AND EASTERN ALGER COUNTY...WHERE OUR LOCAL HIGH RESOLUTION WRF-ARW RUN PRINTS OUT UP TO 0.40 OF AN INCH OF QPF BETWEEN 00Z-12Z. DID NOT GO THIS HIGH...BUT GIVEN A FAVORABLE LAKE ENHANCED SETUP WITH STRONG CONVERGENCE...HAVE ADVISORY LEVEL SNOWFALL IN THE FORECAST. IN ADDITION...HAVE RAISED POPS TO LIKELY ACROSS THE KEWEENAW AND IN THE HIGH QPF AREA SINCE THESE CONTINUE TO LOOK FAVORABLE FOR SNOWFALL. FUTURE SHIFTS WILL NEED TO WATCH THIS EVENT IN CASE IT AMOUNTS TO MORE. GOING FORECAST TEMPS SEEM REASONABLE. WED...SHRTWV TROUGH OVER MONTANA IS PROGGED TO DROP INTO NEBRASKA BY 00Z WHILE A WEAKER EXTENSION OF THIS SHRTWV EXTENDS UP INTO WESTERN LAKE SUPERIOR. THE MAIN EFFECT OF THE TROUGH WILL BE TO SWITCH THE LOW LEVEL WIND FLOW MORE WSW...THEREFORE ALLOWING THE LAKE EFFECT BAND OVER THE NE CWA TO MOVE NORTH DURING THE DAY. LAKE EFFECT SNOW WILL LIKELY AFFECT THE KEWEENAW AREA THOUGH...GIVEN THAT THE WIND FLOW IS STILL NOT TRUE SW...THEREFORE LIKELY POPS WERE MAINTAINED THROUGH THE DAY. ELSEWHERE...GIVEN THE APPROACHING SHRTWV AND STILL PLENTY OF MID LEVEL MOISTURE AROUND...FEEL IT IS STILL PRUDENT TO HAVE SOME SLIGHT CHANCE POPS IN. HOWEVER ANY SYNOPTIC SNOW RIGHT NOW DOES NOT LOOK LIKE A BIG DEAL. HIGH TEMPERATURES APPEAR THAT THEY WILL BE A LITTLE WARMER COMPARED TO TUE AS SW FLOW ALLOW 850MB TEMPS TO CLIMB TO ABOUT 3-5C HIGHER. WED NIGHT AND THU...A MORE SIGNIFICANT SHRTWV TROUGH IS SHOWN BY THE GFS/UKMET/ECMWF TO DROP S THROUGH CANADA INTO THE NORTHERN PLAINS BY THU EVENING (MORE MENTIONED ABOUT THIS SHRTWV IN THE NEXT PERIOD DISCUSSION). THIS SHRTWV WILL CAUSE THE PREVIOUS WEAKER SHRTWV TROUGH OVER WESTERN LAKE SUPERIOR TO CROSS MUCH OF THE CWA EARLY IN THE EVENING. 850MB TEMPS ARE STILL AROUND -16C BEHIND THE SHRTWV...AND WITH A LIGHT TO NEARLY LAND-BREEZE CONVERGENT LOW LEVEL WIND FLOW...LAKE EFFECT CHANCES REMAINS FOR THE WESTERN U.P. WED NIGHT. HAVE KEPT THE REST OF THE CWA DRY...WITH SKIES BECOMING PARTLY CLOUDY AS WEAK RIDGING BUILDS IN AHEAD OF THE SHRTWV. BECAUSE OF THE CLEARING AND LIGHTER WINDS...DROPPED LOW TEMPS A FEW DEGREES. ON THU...AS THE SHRTWV TROUGH AND ASSOCIATED SURFACE LOW APPROACH THE CWA...CLOUD COVER SHOULD BEGIN TO INCREASE AGAIN. FOR NOW HAVE KEPT SOME SLIGHT CHANCE POPS FOR THE WARM ADVECTION AHEAD OF THE TROUGH...BUT AS THE POPS STATE...AM NOT VERY CONFIDENT. HAVE ALSO KEPT 30 POPS IN FOR THE SAME LAKE EFFECT AREA MENTIONED WED NIGHT...BUT WITH THE 950MB AND SURFACE WINDS TURNING TRUE SW AHEAD OF THE SURFACE LOW...THINK MUCH OF THE SNOW MAY END UP BEING IN THE MORNING. HIGH TEMPERATURES ARE EXPECTED TO BE SIMILAR TO WED GIVEN SIMILAR 850MB READINGS AND SOME PARTIAL SUN IN THE MORNING TO HELP OUT. THU NIGHT THROUGH MON...THE WORD FOR THIS PERIOD IS COLD. OPERATIONAL MODELS CONTINUE THE THEME THAT HAS BEEN SHOWN OVER THE PAST WEEK OF SUGGESTING THAT THE POLAR VORTEX CURRENTLY SITUATED NORTH OF HUDSON BAY WILL DIVE SOUTHWARD TOWARDS UPPER MICHIGAN...DUE TO THE DEVELOPMENT OF A VERY AMPLIFIED RIDGE INTO EASTERN ALASKA AND A STRONG SHRTWV NORTH OF ALASKA RIDING DOWN THE EAST SIDE OF THE RIDGE. THIS SHRTWV MAY RESULT IN AN INTERESTING FRI FOR THE CWA AS MODELS NOW INDICATE THAT BOTH IT AND AN ASSOCIATED SURFACE LOW (THE ONE THAT MOVES INTO THE NORTHERN PLAINS AND MINNESOTA ON THU) ARE STRONGER THAN PREVIOUSLY PROGGED. DPVA AND MOISTURE AHEAD OF THE SHRTWV MAY RESULT IN SOME LIGHT SNOW SPREADING ACROSS THE CWA THU NIGHT. THEN ON FRI AS THE SURFACE LOW PASSES ACROSS UPPER MI...THE COLD AIRMASS WITH 850MB TEMPS FALLING INTO THE LOW TO MID -20S C WILL BEGIN ADVECTING INTO THE CWA ON STRONG NW WINDS...POSSIBLY EVEN GALES ON EASTERN LAKE SUPERIOR. GIVEN HOW COLD IT IS...LAKE EFFECT THAT THE DOES FORM ONCE THE COLD AIRMASS MOVES IN WILL LIKELY CONSIST OF SMALL SNOWFLAKES...AND WITH THE WIND...BLOWING SNOW WITH VERY LOW VISIBILITIES MAY BECOME A CONCERN. COLDER AIR IS PROGGED TO CONTINUE ADVECTING INTO THE CWA FRI NIGHT THROUGH SUN AS THE POLAR VORTEX HEADS TOWARDS LAKE SUPERIOR. RIGHT NOW IT APPEARS FROM THE GFS/ECMWF THAT THE VORTEX WILL REACH NORTHERN LAKE SUPERIOR SOME POINT ON SUN...WITH 850MB TEMPS FALLING TO AROUND -30C. IF WINDS CAN BACK TO THE WEST AT NIGHT IN THE INTERIOR AND DIMINISH TO LIGHT...AND SKIES CAN CLEAR...-20S F TEMPERATURES WILL OCCUR. HOWEVER...PLENTY OF UNCERTAINTY EXISTS ON ALL THREE PARAMETERS AT THIS POINT AND RESULTS IN GOING NOW LOWER THAN -15F AT THIS POINT. OTHERWISE...WIND CHILLS WILL BE THE MAIN CONCERN DURING THE WEEKEND GIVEN LOW TEMPERATURES AND BREEZY CONDITIONS...PARTICULARLY OVER THE NORTHERN U.P.. THERE IS SOME UNCERTAINTY ON HOW LONG THE VORTEX WILL STAY AROUND...WITH THE 06Z/12Z GFS MUCH QUICKER ON EXITING IT (SUN NIGHT) COMPARED TO THE 00Z ECMWF WHICH STILL HAS IT NEAR WAWA MON EVENING. PREFER TO STAY CLOSER TO THE SLOWER ECMWF...WHICH IS CLOSE TO HPC PROGS. WILL CONTINUE TO HIGHLIGHT THE UPCOMING COLD IN THE HWO. ON A FINAL NOTE...THE 00Z/12Z ECMWF SUGGESTS THE ARCTIC AIR MIGHT HANG AROUND FOR A FEW MORE DAYS AFTER MON...RAISING SOME CONCERN ABOUT POTENTIAL FOR PIPES UNDERGROUND FREEZING. THIS IS ESPECIALLY TRUE FOR THE SOUTH CENTRAL U.P. WHERE ONLY A FEW INCHES OF SNOW EXIST ON THE GROUND. WILL WAIT AND SEE ON THIS...BUT AT A MINIMUM...EVERYONE SHOULD TRY TO MAKE SURE ANY EXPOSED PIPES ARE INSULATED. && .MQT WATCHES/WARNINGS/ADVISORIES... HEAVY FREEZING SPRAY WARNING WEST 1/2 LAKE SUPERIOR. LAKE EFFECT SNOW WARNING UNTIL 10Z FOR MIZ013-014. && $$ AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 346 PM EST MON JAN 29 2007 ...COLDEST AIR OF THE SEASON TO MOVE INTO WEST AND CENTRAL UPPER MICHIGAN ON FRI... .SYNOPSIS... WATER VAPOR LOOP AND UPR AIR ANALYSIS SHOWS A HIGH AMPLITUDE RDG OVER THE ERN PAC AND NW NOAM WHILE DOWNSTREAM A BROAD TROF IS NOTED MUCH OF CANADA EXTENDING INTO GREAT LAKES AND NE U.S. THIS HIGH AMPLITUDE PATTERN NOT EXPECTED TO CHANGE MUCH THIS WEEK WHICH WILL ALLOW FOR POLAR VORTEX TO WORK ITS WAY SOUTHWARD INTO THE UPR GREAT LAKES BY THE WEEKEND. IN THE SHORT TERM...A SHORTWAVE/CLIPPER SYSTEM DIVING JUST TO OUR S HAS BROUGHT LIGHT SNOW TODAY TO MUCH OF WI AND SOME FLURRIES TO SW UPR MI. WINDS COMING AROUND TO THE N-NE THIS EVENING BEHIND CLIPPER SYSTEM WILL BRING SOME LES BACK ONSHORE TONIGHT INTO TUE. && .SHORT TERM (TONIGHT AND TUE)... THE MAIN CONCERN IS LES FOR TONIGHT INTO TUE. SFC/MARINE OBS SHOWS WINDS ALREADY STARTING TO COME AROUND TO NE OVER WRN LAKE SUPERIOR IN LINE WITH FCST OF RUC AND LOCAL MESOSCALE MODELS. MID-LAKE LES CONVERGENCE BAND OVER LAKE SUPERIOR EXPECTED TO COME ONSHORE THIS EVENING INTO WRN AND NCNTRL COUNTIES AS WINDS SHIFT TO N-NE BEHIND CLIPPER SYSTEM NOW DIVING S. EXPECT A BURST OF HEAVIER SNOW AS CONVERGENCE BAND COMES THROUGH AND THEN LOOK FOR SOME WIND-PARALLEL BANDS SETTING UP BEHIND IT INTO TUE. WEAK ENHANCEMENT THIS EVENING FROM MID-LVL TROF PASSAGE COULD BOOST SNOW AMTS SOME...BUT SHIFTING WINDS WILL NOT FOCUS HEAVY BANDS OVER ANY ONE AREA FOR TOO LONG. BEST CONVERGENCE WITH N-NE FLOW WOULD TEND TO FAVOR MQT COUNTY WHERE MESOSCALE MODEL QPF AROUND .10-.15 INCH COULD BRING TOTAL ACCUMULATIONS UP TO 4 INCHES AT SOME HIGHER TERRAIN LOCATIONS TONIGHT INTO TUE MORNING. SOME LOCATIONS IN GOGEBIC AND ONTONAGON COUNTIES COULD SEE UP TO 3 INCHES. ELSEWHERE ACROSS THE NRN TIER COUNTY...GENERALLY EXPECT 1-2". DID BUMP POPS TO CATEGORICAL FOR WEST AND NCNTRL COUNTIES TONIGHT WITH GOOD CYCLONIC FLOW AND POTENTIAL ENHANCEMENT FROM MID-LVL TROF. LOOKS LIKE LES SHOULD TAPER OFF OR END QUICKLY FOR MOST LOCATIONS BY MIDDAY TUE AS FLOW BECOMES ANTICYCLONIC AND BACKS MORE WRLY WITH BUILDING SFC RDG FROM THE NRN PLAINS. LEFT HIGHER POPS OVER ERN COUNTIES DUE TO LONGER FETCH ACROSS LAKE SUPERIOR IN NW TO W FLOW. .LONG TERM (TUE NIGHT THROUGH MON)... TUE NIGHT...MODELS SHOW A SHRTWV OVER THE NE PORTION OF NUNAVUT MOVING SSE THROUGH THE FLOW ALOFT...MOVING ACROSS NORTHERN ONTARIO DURING THIS TIME PERIOD. THE NAM BRINGS THIS SHRTWV MUCH CLOSER TO THE CWA THAN ALL THE OTHER MODELS (NEAR WAWA BY 06Z)...BUT BELIEVE THIS IS TOO CLOSE GIVEN THAT HEIGHTS ARE PROGGED TO RISE ACROSS THE UPPER MIDWEST AHEAD OF A TROUGH DIGGING INTO MONTANA. THEREFORE WILL FOLLOW THE GFS/REGIONAL CANADIAN AND OUR LOCAL WRF MODELS...WHICH KEEP THE SHRTWV FARTHER TO THE NE. BASICALLY...AS THIS SHRTWV MOVES DOWN...VERY WEAK ISENTROPIC ASCENT AND DPVA HELP TO PRODUCE A MID CLOUD DECK WHICH MOVES OVER THE CWA. AT THE LOW LEVELS...WITH A SURFACE RIDGE TRYING TO BUILD IN FROM THE WEST AND A WEAK TROUGH MOVING S ASSOCIATED WITH THE SHRTWV OVER LAKE SUPERIOR...A CONVERGENT LAKE EFFECT BAND LOOKS LIKELY...AIDED BY LAND BREEZES. RIGHT NOW THE BEST CONVERGENCE IS FOCUSED IN THE NORTHERN PART OF LUCE COUNTY AND EASTERN ALGER COUNTY...WHERE OUR LOCAL HIGH RESOLUTION WRF-ARW RUN PRINTS OUT UP TO 0.40 OF AN INCH OF QPF BETWEEN 00Z-12Z. DID NOT GO THIS HIGH...BUT GIVEN A FAVORABLE LAKE ENHANCED SETUP WITH STRONG CONVERGENCE...HAVE ADVISORY LEVEL SNOWFALL IN THE FORECAST. IN ADDITION...HAVE RAISED POPS TO LIKELY ACROSS THE KEWEENAW AND IN THE HIGH QPF AREA SINCE THESE CONTINUE TO LOOK FAVORABLE FOR SNOWFALL. FUTURE SHIFTS WILL NEED TO WATCH THIS EVENT IN CASE IT AMOUNTS TO MORE. GOING FORECAST TEMPS SEEM REASONABLE. WED...SHRTWV TROUGH OVER MONTANA IS PROGGED TO DROP INTO NEBRASKA BY 00Z WHILE A WEAKER EXTENSION OF THIS SHRTWV EXTENDS UP INTO WESTERN LAKE SUPERIOR. THE MAIN EFFECT OF THE TROUGH WILL BE TO SWITCH THE LOW LEVEL WIND FLOW MORE WSW...THEREFORE ALLOWING THE LAKE EFFECT BAND OVER THE NE CWA TO MOVE NORTH DURING THE DAY. LAKE EFFECT SNOW WILL LIKELY AFFECT THE KEWEENAW AREA THOUGH...GIVEN THAT THE WIND FLOW IS STILL NOT TRUE SW...THEREFORE LIKELY POPS WERE MAINTAINED THROUGH THE DAY. ELSEWHERE...GIVEN THE APPROACHING SHRTWV AND STILL PLENTY OF MID LEVEL MOISTURE AROUND...FEEL IT IS STILL PRUDENT TO HAVE SOME SLIGHT CHANCE POPS IN. HOWEVER ANY SYNOPTIC SNOW RIGHT NOW DOES NOT LOOK LIKE A BIG DEAL. HIGH TEMPERATURES APPEAR THAT THEY WILL BE A LITTLE WARMER COMPARED TO TUE AS SW FLOW ALLOW 850MB TEMPS TO CLIMB TO ABOUT 3-5C HIGHER. WED NIGHT AND THU...A MORE SIGNIFICANT SHRTWV TROUGH IS SHOWN BY THE GFS/UKMET/ECMWF TO DROP S THROUGH CANADA INTO THE NORTHERN PLAINS BY THU EVENING (MORE MENTIONED ABOUT THIS SHRTWV IN THE NEXT PERIOD DISCUSSION). THIS SHRTWV WILL CAUSE THE PREVIOUS WEAKER SHRTWV TROUGH OVER WESTERN LAKE SUPERIOR TO CROSS MUCH OF THE CWA EARLY IN THE EVENING. 850MB TEMPS ARE STILL AROUND -16C BEHIND THE SHRTWV...AND WITH A LIGHT TO NEARLY LAND-BREEZE CONVERGENT LOW LEVEL WIND FLOW...LAKE EFFECT CHANCES REMAINS FOR THE WESTERN U.P. WED NIGHT. HAVE KEPT THE REST OF THE CWA DRY...WITH SKIES BECOMING PARTLY CLOUDY AS WEAK RIDGING BUILDS IN AHEAD OF THE SHRTWV. BECAUSE OF THE CLEARING AND LIGHTER WINDS...DROPPED LOW TEMPS A FEW DEGREES. ON THU...AS THE SHRTWV TROUGH AND ASSOCIATED SURFACE LOW APPROACH THE CWA...CLOUD COVER SHOULD BEGIN TO INCREASE AGAIN. FOR NOW HAVE KEPT SOME SLIGHT CHANCE POPS FOR THE WARM ADVECTION AHEAD OF THE TROUGH...BUT AS THE POPS STATE...AM NOT VERY CONFIDENT. HAVE ALSO KEPT 30 POPS IN FOR THE SAME LAKE EFFECT AREA MENTIONED WED NIGHT...BUT WITH THE 950MB AND SURFACE WINDS TURNING TRUE SW AHEAD OF THE SURFACE LOW...THINK MUCH OF THE SNOW MAY END UP BEING IN THE MORNING. HIGH TEMPERATURES ARE EXPECTED TO BE SIMILAR TO WED GIVEN SIMILAR 850MB READINGS AND SOME PARTIAL SUN IN THE MORNING TO HELP OUT. THU NIGHT THROUGH MON...THE WORD FOR THIS PERIOD IS COLD. OPERATIONAL MODELS CONTINUE THE THEME THAT HAS BEEN SHOWN OVER THE PAST WEEK OF SUGGESTING THAT THE POLAR VORTEX CURRENTLY SITUATED NORTH OF HUDSON BAY WILL DIVE SOUTHWARD TOWARDS UPPER MICHIGAN...DUE TO THE DEVELOPMENT OF A VERY AMPLIFIED RIDGE INTO EASTERN ALASKA AND A STRONG SHRTWV NORTH OF ALASKA RIDING DOWN THE EAST SIDE OF THE RIDGE. THIS SHRTWV MAY RESULT IN AN INTERESTING FRI FOR THE CWA AS MODELS NOW INDICATE THAT BOTH IT AND AN ASSOCIATED SURFACE LOW (THE ONE THAT MOVES INTO THE NORTHERN PLAINS AND MINNESOTA ON THU) ARE STRONGER THAN PREVIOUSLY PROGGED. DPVA AND MOISTURE AHEAD OF THE SHRTWV MAY RESULT IN SOME LIGHT SNOW SPREADING ACROSS THE CWA THU NIGHT. THEN ON FRI AS THE SURFACE LOW PASSES ACROSS UPPER MI...THE COLD AIRMASS WITH 850MB TEMPS FALLING INTO THE LOW TO MID -20S C WILL BEGIN ADVECTING INTO THE CWA ON STRONG NW WINDS...POSSIBLY EVEN GALES ON EASTERN LAKE SUPERIOR. GIVEN HOW COLD IT IS...LAKE EFFECT THAT THE DOES FORM ONCE THE COLD AIRMASS MOVES IN WILL LIKELY CONSIST OF SMALL SNOWFLAKES...AND WITH THE WIND...BLOWING SNOW WITH VERY LOW VISIBILITIES MAY BECOME A CONCERN. COLDER AIR IS PROGGED TO CONTINUE ADVECTING INTO THE CWA FRI NIGHT THROUGH SUN AS THE POLAR VORTEX HEADS TOWARDS LAKE SUPERIOR. RIGHT NOW IT APPEARS FROM THE GFS/ECMWF THAT THE VORTEX WILL REACH NORTHERN LAKE SUPERIOR SOME POINT ON SUN...WITH 850MB TEMPS FALLING TO AROUND -30C. IF WINDS CAN BACK TO THE WEST AT NIGHT IN THE INTERIOR AND DIMINISH TO LIGHT...AND SKIES CAN CLEAR...-20S F TEMPERATURES WILL OCCUR. HOWEVER...PLENTY OF UNCERTAINTY EXISTS ON ALL THREE PARAMETERS AT THIS POINT AND RESULTS IN GOING NOW LOWER THAN -15F AT THIS POINT. OTHERWISE...WIND CHILLS WILL BE THE MAIN CONCERN DURING THE WEEKEND GIVEN LOW TEMPERATURES AND BREEZY CONDITIONS...PARTICULARLY OVER THE NORTHERN U.P.. THERE IS SOME UNCERTAINTY ON HOW LONG THE VORTEX WILL STAY AROUND...WITH THE 06Z/12Z GFS MUCH QUICKER ON EXITING IT (SUN NIGHT) COMPARED TO THE 00Z ECMWF WHICH STILL HAS IT NEAR WAWA MON EVENING. PREFER TO STAY CLOSER TO THE SLOWER ECMWF...WHICH IS CLOSE TO HPC PROGS. WILL CONTINUE TO HIGHLIGHT THE UPCOMING COLD IN THE HWO. ON A FINAL NOTE...THE 00Z/12Z ECMWF SUGGESTS THE ARCTIC AIR MIGHT HANG AROUND FOR A FEW MORE DAYS AFTER MON...RAISING SOME CONCERN ABOUT POTENTIAL FOR PIPES UNDERGROUND FREEZING. THIS IS ESPECIALLY TRUE FOR THE SOUTH CENTRAL U.P. WHERE ONLY A FEW INCHES OF SNOW EXIST ON THE GROUND. WILL WAIT AND SEE ON THIS...BUT AT A MINIMUM...EVERYONE SHOULD TRY TO MAKE SURE ANY EXPOSED PIPES ARE INSULATED. && .MQT WATCHES/WARNINGS/ADVISORIES... HEAVY FREEZING SPRAY WARNING WEST 1/2 LAKE SUPERIOR. && $$ AJ mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 1142 AM EST MON JAN 29 2007 .UPDATE... NO BIG CHANGES ON THE UPDATE. BASICALLY LOOKS LIKE FLURRIES/LIGHT -SN WILL BE CONFINED TO THE WI BDR BORDER COUNTIES THIS AFTERNOON AS BEST 275K ISENTROPIC ASCENT FM CLIPPER SYSTEM DIVING INTO NW WI WILL STAY GENERALLY S OF FCST AREA. WINDS SHIFTING NE BEHIND THIS SYSTEM WILL BRING LES CONVERGENCE BAND NOW OVER NCNTRL AND ERN LAKE SUPERIOR ONSHORE THIS EVENING. HIGH TEMPS IN TEENS GENERALLY STILL ON TRACK FOR THIS AFTERNOON BASED ON LOCAL SNDGS. && .PREV DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE SNOW POTENTIAL FOR TODAY AND TONIGHT. WATER VAPOR IMAGERY AND RUC SHOWING A LARGE RIDGE OFF THE PACIFIC NORTHWEST AND A LONGWAVE TROUGH BLANKETING MUCH OF THE EASTERN CANADA AND NORTHEAST CONUS. A LOW CENTER SWEEPING THROUGH THE BASE OF THIS LONGWAVE TROUGH IS OVER NORTHERN MINNESOTA. SEVERAL WEAK SHORTWAVE ACCOMPANY THIS LOW CENTER AND ARE OVER WISCONSIN... SOUTHERN SOUTH DAKOTA...AND CENTRAL NORTH DAKOTA. SURFACE ANALYSIS DEPICT A RIDGE EXTENDING FROM A HIGH OVER THE LOWER MISSISSIPPI RIVER VALLEY THROUGH WESTERN OHIO RIVER VALLEY AND THE UPPER GREAT LAKES. A LOW ASSOCIATED WITH THIS MID LEVEL ONE IS OVER NORTHWEST MINNESOTA. A FRONTAL SYSTEM ASSOCIATED WITH THIS LOW IS LIES ALONG THE UPPER AND MIDDLE MISSISSIPPI RIVER. DEEP MOISTURE ACCOMPANYING THIS SYSTEM IS OVER WISCONSIN...MINNESOTA...AND THE DAKOTAS. KMQT-88D AND SAT IR SHOW WEAK LAKE EFFECT SNOW BANDS PERSISTING OVER THE EASTERN U.P. THE LOW WILL WEAKEN INTO JUST A SHORTWAVE TROUGH AS IT SWEEPS THROUGH THE FORECAST AREA TODAY. THE ACCOMPANYING Q-VECTOR CONVERGENCE ASSOCIATED WITH THE LOW WILL BECOME FOCUSED OVER THE U.P. BY LATE AFTERNOON. THE 850MB TEMPERATURE WILL REMAIN AROUND -19C ACROSS THE AREA. MODELS SHOWING THE DEEP MOISTURE WILL MAINLY BE FOCUSED OVER WISCONSIN AND ADJACENT AREAS OF THE U.P. THE SURFACE LOW OVER MINNESOTA WILL DIVE INTO CENTRAL WISCONSIN BY MID DAY AND THEN MOVE EAST INTO CENTRAL LAKE MICHIGAN BY LATE AFTERNOON. CYCLONIC FLOW AROUND THIS LOW WILL CAUSE WINDS TO BE LIGHT EARLY THEN BECOME MORE NORTH AND NORTHEAST ACROSS LAKE SUPERIOR THROUGH THE DAY. THE SURFACE BASED INVERSION OVER THE AREA WILL LIFT TO AROUND 925MB BY MID DAY AND TO AROUND 850MB BY DUSK. CONDITIONS FAVOR WEAK LAKE EFFECT SNOWS OVER THE EASTERN LAKE SUPERIOR AND ADJACENT LANDS THIS MORNING. WITH INCREASED LOW LEVEL ADIABATIC LIFT WITH THE HIGHER INVERSION...LAKE-850MB DELTA-T`S OF 22C...AND WEAK LOW LEVEL CONVERGENCE THERE SHOULD BE AN INCREASE OF LAKE EFFECT SNOWS. WINDS WILL BE OUT OF THE NORTHEAST OVER THE LAKE BY LATE AFTERNOON SO NORTH CENTRAL U.P. WILL BE MOST LIKELY AREAS TO RECEIVE THE HEAVIEST LES. THE LIMITING FACTORS SEEM TO BE THE LACK OF ANY DEEP MOISTURE AND THE WEAK LOW LEVEL CONVERGENCE. THUS PLAN TO KEEP SOME LAKE EFFECT SNOW GOING OVER THE EAST AND ADD SYSTEM SNOWS SPREADING INTO THE AREA ALONG THE WISCONSIN BORDER. THE SHORTWAVE OVER THE FORECAST AREA THIS EVENING WILL SHIFT SOUTHEAST INTO LOWER MICHIGAN TONIGHT AS THE INSTABILITY OVER SOUTH CENTRAL CANADA SWINGS INTO NORTHERN MINNESOTA AND CENTRAL ONTARIO. THE SURFACE LOW WILL SWING INTO SOUTHEAST LOWER MICHIGAN AND EXTREME SOUTHERN ONTARIO...WHILE A LARGE RIDGE BUILDS OVER THE NORTHERN PLAINS. Q-VECTOR CONVERGENCE FOCUS WILL SHIFT INTO LAKE HURON. SURFACE WINDS WILL REMAIN OUT OF THE NORTH OVER LAKE SUPERIOR. THE DELTA-T`S OVER THE LAKE WILL BE AROUND 22C AND THE LOWEST INVERSION LEVEL WILL CONTINUE AROUND 850MB. THE FORECAST SOUNDINGS SUGGEST AT THE LOW LEVEL CONDITIONS WILL BE LITTLE DRIER. LOW LEVEL CONVERGENCE WILL ALSO BE WEAK. THUS LAKE EFFECT SNOW SHOULD CONTINUE OVER THE NORTHERN U.P. AND SYSTEM SNOWS ASSOCIATED WITH MOISTURE WRAP AROUND THE SURFACE LOW AND ISENTROPIC ASCENT ASSOCIATED WITH THIS SYSTEM PRODUCE SNOWS OVER THE SOUTH. AS ONE SHORTWAVE SWEEPS THROUGH THE AREA ON TUESDAY ANOTHER WILL FOLLOWING INTO CENTRAL ONTARIO. THE Q-VECTOR CONVERGENCE WILL SHIFT INTO THE WEST AND CENTRAL LAKE SUPERIOR. THE SURFACE LOW WILL MOVE INTO THE OHIO RIVER VALLEY. THE NORTHERN PLAINS RIDGE WILL KEEP THE WINDS OUT OF THE NORTH IN THE MORNING. AS THE RIDGE SETTLES IN MISSOURI ON TUESDAY THE WINDS OVER THE FORECAST AREA WILL BACK WEST. ANOTHER LOW WILL FILL SLOWLY AS IT MOVES INTO SOUTHERN MANITOBA. 850MB TEMPERATURES WILL CONTINUE TO BE AROUND -19C. MODELS SHOWING 925MB WINDS INDICATING LOW LEVEL CONVERGENCE. DEEP MOISTURE WILL BE LIMITED...HOWEVER...LES SHOULD PERSIST. THE BACKING WINDS WILL BE THE MAIN FACTOR TO DETERMINE WHO WILL BE GETTING THE LES. SINCE IT WILL BE SHIFTING NO ONE AREA SHOULD BE GETTING THE SIGNIFICANT ACCUMULATIONS. A WEAK SHORTWAVE WILL SAIL ACROSS THE FORECAST AREA TUESDAY NIGHT FOLLOWED BY A LITTLE DEEPER SHORTWAVE LATE. MODELS SHOWING PREVALENT LOW LEVEL CONVERGENCE ACROSS LAKE SUPERIOR. THE SURFACE HIGH WILL PUSH INTO MIDDLE MISSISSIPPI RIVER VALLEY WHILE A LOW MOVES INTO SOUTHEAST NORTH DAKOTA. WINDS WILL BE OUT OF THE SOUTHWEST OF THE U.P...WHILE OVER LAKE SUPERIOR THE WINDS WILL BE MORE OUT OF THE WEST. A COLD FRONT WILL ACCOMPANY THE LOW IN NORTH DAKOTA. THIS ALONG WITH THE HIGH WILL DRAW MORE DEEP MOIST AIR INTO THE AREA. THE 850MB TEMPERATURE WILL STILL BE AROUND -18C. CONDITIONS LOOK FAVORABLE FOR LAKE EFFECT SNOWS TO CONTINUE MAINLY ALONG THE LAKE SHORE WITH A SLIGHT NORTHWEST FLOW. ANOTHER SHORTWAVE WILL PASS THROUGH THE AREA ON WEDNESDAY ACCOMPANIED BY AN AREA OF Q-VECTOR CONVERGENCE. 850MB TEMPERATURES OVER THE LAKE WILL REMAIN AROUND -19C. THE SURFACE LOW WILL MEANDER ACROSS CENTRAL ONTARIO DRAWING THE COLD FRONT THROUGH THE FORECAST AREA. ISENTROPIC ASCENT ASSOCIATED WITH THE FRONTAL SYSTEM WILL SQUEEZE MORE SNOW OUT OVER THE FORECAST AREA. ANOTHER WEAK SHORTWAVE WILL RACE INTO LOWER MICHIGAN ON WEDNESDAY NIGHT. THE WINDS WILL VEER NORTHWEST AFTER THE FROPA. 850MB TEMPERATURES ARE EXPECTED TO BE A LITTLE WARMER (-15C TO 17C) ACROSS THE LAKE BUT STILL COOL ENOUGH TO KEEP A MENTION OF LAKE EFFECT SNOWS OVER THE NORTHERN U.P. WHERE LES IS PRONE TO OCCUR WITH A WEST NORTHWEST FLOW. ON THURSDAY ANOTHER LOW WILL SETTLE OUT OF SOUTH CENTRAL CANADA AND MOVE INTO NORTHERN MINNESOTA WHILE DRAGGING A COLD FRONT INTO THE UPPER MISSISSIPPI RIVER VALLEY. ISENTROPIC ASCENT AHEAD OF THE FRONTAL SYSTEM SHOULD SQUEEZE MORE LIGHT SNOW OUT OVER THE AREA. THE SOUTHWESTERLY FLOW WILL ALSO BRING A LITTLE WARMER TEMPERATURES. THE LOW WILL REACH CENTRAL LAKE SUPERIOR ON THURSDAY. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VOSS (UPDATE) DLG (PREV DISCUSSION) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 345 AM EST MON JAN 29 2007 .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE SNOW POTENTIAL FOR TODAY AND TONIGHT. WATER VAPOR IMAGERY AND RUC SHOWING A LARGE RIDGE OFF THE PACIFIC NORTHWEST AND A LONGWAVE TROUGH BLANKETING MUCH OF THE EASTERN CANADA AND NORTHEAST CONUS. A LOW CENTER SWEEPING THROUGH THE BASE OF THIS LONGWAVE TROUGH IS OVER NORTHERN MINNESOTA. SEVERAL WEAK SHORTWAVE ACCOMPANY THIS LOW CENTER AND ARE OVER WISCONSIN... SOUTHERN SOUTH DAKOTA...AND CENTRAL NORTH DAKOTA. SURFACE ANALYSIS DEPICT A RIDGE EXTENDING FROM A HIGH OVER THE LOWER MISSISSIPPI RIVER VALLEY THROUGH WESTERN OHIO RIVER VALLEY AND THE UPPER GREAT LAKES. A LOW ASSOCIATED WITH THIS MID LEVEL ONE IS OVER NORTHWEST MINNESOTA. A FRONTAL SYSTEM ASSOCIATED WITH THIS LOW IS LIES ALONG THE UPPER AND MIDDLE MISSISSIPPI RIVER. DEEP MOISTURE ACCOMPANYING THIS SYSTEM IS OVER WISCONSIN...MINNESOTA...AND THE DAKOTAS. KMQT-88D AND SAT IR SHOW WEAK LAKE EFFECT SNOW BANDS PERSISTING OVER THE EASTERN U.P. THE LOW WILL WEAKEN INTO JUST A SHORTWAVE TROUGH AS IT SWEEPS THROUGH THE FORECAST AREA TODAY. THE ACCOMPANYING Q-VECTOR CONVERGENCE ASSOCIATED WITH THE LOW WILL BECOME FOCUSED OVER THE U.P. BY LATE AFTERNOON. THE 850MB TEMPERATURE WILL REMAIN AROUND -19C ACROSS THE AREA. MODELS SHOWING THE DEEP MOISTURE WILL MAINLY BE FOCUSED OVER WISCONSIN AND ADJACENT AREAS OF THE U.P. THE SURFACE LOW OVER MINNESOTA WILL DIVE INTO CENTRAL WISCONSIN BY MID DAY AND THEN MOVE EAST INTO CENTRAL LAKE MICHIGAN BY LATE AFTERNOON. CYCLONIC FLOW AROUND THIS LOW WILL CAUSE WINDS TO BE LIGHT EARLY THEN BECOME MORE NORTH AND NORTHEAST ACROSS LAKE SUPERIOR THROUGH THE DAY. THE SURFACE BASED INVERSION OVER THE AREA WILL LIFT TO AROUND 925MB BY MID DAY AND TO AROUND 850MB BY DUSK. CONDITIONS FAVOR WEAK LAKE EFFECT SNOWS OVER THE EASTERN LAKE SUPERIOR AND ADJACENT LANDS THIS MORNING. WITH INCREASED LOW LEVEL ADIABATIC LIFT WITH THE HIGHER INVERSION...LAKE-850MB DELTA-T`S OF 22C...AND WEAK LOW LEVEL CONVERGENCE THERE SHOULD BE AN INCREASE OF LAKE EFFECT SNOWS. WINDS WILL BE OUT OF THE NORTHEAST OVER THE LAKE BY LATE AFTERNOON SO NORTH CENTRAL U.P. WILL BE MOST LIKELY AREAS TO RECEIVE THE HEAVIEST LES. THE LIMITING FACTORS SEEM TO BE THE LACK OF ANY DEEP MOISTURE AND THE WEAK LOW LEVEL CONVERGENCE. THUS PLAN TO KEEP SOME LAKE EFFECT SNOW GOING OVER THE EAST AND ADD SYSTEM SNOWS SPREADING INTO THE AREA ALONG THE WISCONSIN BORDER. THE SHORTWAVE OVER THE FORECAST AREA THIS EVENING WILL SHIFT SOUTHEAST INTO LOWER MICHIGAN TONIGHT AS THE INSTABILITY OVER SOUTH CENTRAL CANADA SWINGS INTO NORTHERN MINNESOTA AND CENTRAL ONTARIO. THE SURFACE LOW WILL SWING INTO SOUTHEAST LOWER MICHIGAN AND EXTREME SOUTHERN ONTARIO...WHILE A LARGE RIDGE BUILDS OVER THE NORTHERN PLAINS. Q-VECTOR CONVERGENCE FOCUS WILL SHIFT INTO LAKE HURON. SURFACE WINDS WILL REMAIN OUT OF THE NORTH OVER LAKE SUPERIOR. THE DELTA-T`S OVER THE LAKE WILL BE AROUND 22C AND THE LOWEST INVERSION LEVEL WILL CONTINUE AROUND 850MB. THE FORECAST SOUNDINGS SUGGEST AT THE LOW LEVEL CONDITIONS WILL BE LITTLE DRIER. LOW LEVEL CONVERGENCE WILL ALSO BE WEAK. THUS LAKE EFFECT SNOW SHOULD CONTINUE OVER THE NORTHERN U.P. AND SYSTEM SNOWS ASSOCIATED WITH MOISTURE WRAP AROUND THE SURFACE LOW AND ISENTROPIC ASCENT ASSOCIATED WITH THIS SYSTEM PRODUCE SNOWS OVER THE SOUTH. AS ONE SHORTWAVE SWEEPS THROUGH THE AREA ON TUESDAY ANOTHER WILL FOLLOWING INTO CENTRAL ONTARIO. THE Q-VECTOR CONVERGENCE WILL SHIFT INTO THE WEST AND CENTRAL LAKE SUPERIOR. THE SURFACE LOW WILL MOVE INTO THE OHIO RIVER VALLEY. THE NORTHERN PLAINS RIDGE WILL KEEP THE WINDS OUT OF THE NORTH IN THE MORNING. AS THE RIDGE SETTLES IN MISSOURI ON TUESDAY THE WINDS OVER THE FORECAST AREA WILL BACK WEST. ANOTHER LOW WILL FILL SLOWLY AS IT MOVES INTO SOUTHERN MANITOBA. 850MB TEMPERATURES WILL CONTINUE TO BE AROUND -19C. MODELS SHOWING 925MB WINDS INDICATING LOW LEVEL CONVERGENCE. DEEP MOISTURE WILL BE LIMITED...HOWEVER...LES SHOULD PERSIST. THE BACKING WINDS WILL BE THE MAIN FACTOR TO DETERMINE WHO WILL BE GETTING THE LES. SINCE IT WILL BE SHIFTING NO ONE AREA SHOULD BE GETTING THE SIGNIFICANT ACCUMULATIONS. A WEAK SHORTWAVE WILL SAIL ACROSS THE FORECAST AREA TUESDAY NIGHT FOLLOWED BY A LITTLE DEEPER SHORTWAVE LATE. MODELS SHOWING PREVALENT LOW LEVEL CONVERGENCE ACROSS LAKE SUPERIOR. THE SURFACE HIGH WILL PUSH INTO MIDDLE MISSISSIPPI RIVER VALLEY WHILE A LOW MOVES INTO SOUTHEAST NORTH DAKOTA. WINDS WILL BE OUT OF THE SOUTHWEST OF THE U.P...WHILE OVER LAKE SUPERIOR THE WINDS WILL BE MORE OUT OF THE WEST. A COLD FRONT WILL ACCOMPANY THE LOW IN NORTH DAKOTA. THIS ALONG WITH THE HIGH WILL DRAW MORE DEEP MOIST AIR INTO THE AREA. THE 850MB TEMPERATURE WILL STILL BE AROUND -18C. CONDITIONS LOOK FAVORABLE FOR LAKE EFFECT SNOWS TO CONTINUE MAINLY ALONG THE LAKE SHORE WITH A SLIGHT NORTHWEST FLOW. ANOTHER SHORTWAVE WILL PASS THROUGH THE AREA ON WEDNESDAY ACCOMPANIED BY AN AREA OF Q-VECTOR CONVERGENCE. 850MB TEMPERATURES OVER THE LAKE WILL REMAIN AROUND -19C. THE SURFACE LOW WILL MEANDER ACROSS CENTRAL ONTARIO DRAWING THE COLD FRONT THROUGH THE FORECAST AREA. ISENTROPIC ASCENT ASSOCIATED WITH THE FRONTAL SYSTEM WILL SQUEEZE MORE SNOW OUT OVER THE FORECAST AREA. ANOTHER WEAK SHORTWAVE WILL RACE INTO LOWER MICHIGAN ON WEDNESDAY NIGHT. THE WINDS WILL VEER NORTHWEST AFTER THE FROPA. 850MB TEMPERATURES ARE EXPECTED TO BE A LITTLE WARMER (-15C TO 17C) ACROSS THE LAKE BUT STILL COOL ENOUGH TO KEEP A MENTION OF LAKE EFFECT SNOWS OVER THE NORTHERN U.P. WHERE LES IS PRONE TO OCCUR WITH A WEST NORTHWEST FLOW. ON THURSDAY ANOTHER LOW WILL SETTLE OUT OF SOUTH CENTRAL CANADA AND MOVE INTO NORTHERN MINNESOTA WHILE DRAGGING A COLD FRONT INTO THE UPPER MISSISSIPPI RIVER VALLEY. ISENTROPIC ASCENT AHEAD OF THE FRONTAL SYSTEM SHOULD SQUEEZE MORE LIGHT SNOW OUT OVER THE AREA. THE SOUTHWESTERLY FLOW WILL ALSO BRING A LITTLE WARMER TEMPERATURES. THE LOW WILL REACH CENTRAL LAKE SUPERIOR ON THURSDAY. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1155 PM EST SUN JAN 28 2007 .AVIATION... MAINLY VFR CONDITIONS EARLY IN THE TAF FORECAST PERIOD...WILL GRADUALLY GIVE WAY TO MVFR CIGS AFTER 08Z AS WEST TO SOUTHWEST RETURN FLOW DEVELOPS OVER LAKE MICHIGAN AS SURFACE HIGH SINKS A LITTLE FURTHER SOUTH INTO THE OHIO VALLEY. COLD AND UNSTABLE AIR OVER LAKE MICHIGAN WILL DRIVE MVFR CLOUDS BACK INTO THE REGION BETWEEN 06-09Z WITH A CHANCE OF A FEW FLURRIES. WINDS TO BACK EVEN FURTHER TO THE SOUTHWEST 12-18Z AHEAD OF NEXT CLIPPER LOW...WHICH WILL RESULT IN PERIODS OF VFR CONDITIONS IN THE DTW AREA...WITH AC DECK 080-100 ADVANCING INTO THE DTW AREA 15-21Z...AHEAD OF NEXT SYSTEM. ANTICIPATE GOOD ISENTROPIC SATURATION 21Z-00Z AS NOTED ON 280K SURFACE...AND GIVEN PRECIPITATION ALREADY OCCURRING IN CENTRAL MINNESOTA. BEST LEFT WILL BE ALONG AND SOUTH OF SURFACE LOW TRACK...WITH SNOW SPREADING BACK INTO THE REGION BY 00Z AND CONTINUING THROUGH 06Z. BEST LIFT WILL FOCUS SOUTH OF FNT WHERE PERIODS OF IFR CONDITIONS ARE EXPECTED 00-06Z...MAINLY MVFR CONDITIONS FROM FNT NORTHWARD. && .PREV DISCUSSION...ISSUED 346 PM EST SUN JAN 28 2007 SHORT TERM...TONIGHT SURFACE TROUGH AXIS WILL BE MIGRATING FROM THE VICINITY OF 8-MILE ROAD TO SOUTH OF THE MICHIGAN STATE LINE THIS EVENING. LAKE EFFECT SNOW CONTINUES TO PLAGUE THE THUMB DOWN ACROSS THE REMAINDER OF THE ADJACENT LAKE HURON COUNTIES WITH RECENT SIGNS OF WEAKENING ACROSS HURON/TUSCOLA COUNTIES. HOWEVER...AS BOUNDARY LAYER WINDS BECOME MORE NORTHERLY WITH THE PASSAGE OF THE SURFACE TROUGH AND UPPER LEVEL LOW...THERE COULD BE ONE MAIN BAND TO IMPACT THE M 25 CORRIDOR THIS EVENING BEFORE SHIFTING OFFSHORE BY 03Z. THIS IS SUGGESTED BY THE 18Z RUC AND TO SOME EXTENT BY THE 18Z NAM (ALBEIT WEAKER) SO WILL HAVE TO EXTEND THE ADVISORY/WARNING FOR A FEW MORE HOURS THIS EVENING TO ACCOUNT FOR THIS ACTIVITY. FLOW CONTINUES TO BACK TO THE NORTHWEST TONIGHT TAKING LAKE EFFECT BAND WELL OFFSHORE. THIS COULD PROVIDE A BRIEF PERIOD OF SOME DOWNSLOPING WINDS WITH PTCLOUDY CONDITIONS. THIS COULD GIVE THE CWA A PERIOD OF TEMPERATURES TO DROP BACK RATHER QUICKLY (ESPECIALLY WHERE FRESH SNOW COVER HAS OCCURRED TODAY) BEFORE LEVELING OFF OVERNIGHT. AS FLOW CONTINUES TO BACK TOWARD THE WEST AND LINGERING INSTABILITY OVER LAKE MICHIGAN...WILL LIKELY SEE THE STRATUS DECK MOVE BACK INTO THE REGION OVERNIGHT WITH THE CHANCE FOR ADDITIONAL FLURRIES. WILL SHADE OVERNIGHT LOW TEMPERATURES CLOSER TO THE BLEND OF THE MAV/FWC THAN THE MET GUIDANCE WHICH SEEMS A BIT WARM CONSIDERING DEW POINTS UPSTREAM ARE IN THE SINGLE DIGITS. LONG TERM...MONDAY THROUGH NEXT SUNDAY COLD AND DRY HIGH PRESSURE WILL BE IN PLACE TO START THE DAY ON MONDAY. THE DRY AIR IN THE LOW LEVELS TENDS TO SUPPORT A SLOWER ONSET OF SNOW WITH THE NEXT CANADIAN CLIPPER SYSTEM, MORE IN LINE WITH THE NAM KEEPING THINGS DRY THROUGH THE DAY. AFTER OVERCOMING DRY AIR IN THE LOW LEVELS, SNOW SHOWERS WILL THEN BECOME LIKELY ALONG THE TRACK OF THE SURFACE LOW AND TRAILING COLD FRONT AFTER MIDNIGHT WITH LOWER CHANCES TO THE NORTH TOWARD THE TRI CITIES AND NORTHERN THUMB. THE BEST SURFACE CONVERGENCE WILL GET A BOOST FROM LAKE MICHIGAN DURING THE OVERNIGHT HOURS AND IN THE VICINITY OF THE I 96 CORRIDOR. ACTIVITY WILL ALSO BENEFIT FROM SHORT WAVE FORCING IN THE FORM OF DCVA EARLY AND DEFORMATION LATER IN THE NIGHT. ACCUMULATION POTENTIAL LOOKS ON THE LIGHT SIDE WITH AN INCH OR TWO THE BEST TARGET RANGE. THE 12Z MODELS SHOW THE WAVE BRINGING SPECIFIC HUMIDITY AROUND 1 G/KG AT 700 MB. THIS PARAMETER BEING ABOUT EQUAL AMONG THE MODELS INDICATES QPF NEAR A TENTH INCH FROM THE NAM AND GFS LOOKS BETTER THAN LIGHTER AMOUNTS OFFERED FROM OTHER SOLUTIONS. SNOW SHOWERS WILL LINGER ALONG THE COLD FRONT INTO TUESDAY MORNING, AS WILL A CHANCE DUE TO A NARROW WINDOW OF LAKE EFFECT IN THE THUMB. HOWEVER, IT WILL BE HARD TO RULE OUT A CHANCE OF SNOW SHOWERS DURING THE AFTERNOON AS WELL, EVEN AS THE WIND TURNS TOWARD THE NORTHWEST. THE COLD AIR IN PLACE, DIURNAL ENHANCEMENT, AND ANY SNOW SHOWERS FROM LAKE MICHIGAN WILL KEEP THE CHANCE GOING THROUGH THE DAY IN SE MICHIGAN. THERE IS GOOD MODEL AGREEMENT SHOWING OUR AREA BETWEEN SYSTEMS TUESDAY NIGHT AND WEDNESDAY. COLD NW FLOW ALOFT WILL PERSIST BUT DRY AIR WILL BUILD INTO THE REGION IN THE LOW LEVELS WITH SURFACE HIGH PRESSURE MOVING TO OUR SOUTH. THIS DRY AIR WILL ELIMINATE SNOW SHOWERS FROM LAKE MICHIGAN BUT PROBABLY NOT STRATUS DOWNSTREAM OF LAKE MICHIGAN. THE SLOWLY BACKING WIND DIRECTION WILL TEND TO KEEP THE TRI CITIES, FLINT, AND THUMB IN THE CLOUDS WITH 925 MB TEMPS AROUND -13C. SECTIONS SOUTH OF THAT TO THE OHIO BORDER WILL BREAK OUT IN SOME SUNSHINE BY AFTERNOON AS THE FLOW BECOMES MORE FROM INDIANA RATHER THAN HAVING A LAKE TRAJECTORY. THE NEXT WAVE IN THE PERPETUAL NW FLOW ALOFT IS SHOWN TO ARRIVE WEDNESDAY NIGHT BY THE GFS. THIS SOLUTION IS STRONGER THAN THAT OFFERED BY THE 12Z ECMWF WHICH SHEARS THE WAVE THROUGH LOWER MICHIGAN FASTER AND MORE WEAKLY. HEIGHT FALLS OCCURRING IN THE PLAINS AND ROCKIES MIGHT SUPPORT THE ECMWF SOLUTION ON THE SHORT WAVE BUT EITHER WAY IT IS WORTH A CHANCE OF LIGHT SNOW, EVEN THE STRONGER GFS CAN ONLY PRODUCE A FEW 100THS OF QPF BOTH WEDNESDAY NIGHT AND THURSDAY. THE COLD FRONT TRAILING THIS SYSTEM WILL MOVE THROUGH OUR AREA AND KEEP COLD CONDITIONS IN PLACE THROUGH FRIDAY UNTIL YET ANOTHER SHORT WAVE IS SHOWN TO MOVE INTO THE REGION. THERE COULD BE SOME MODEST TEMPERATURE MODERATION IN THE SW FLOW AHEAD OF THIS SYSTEM, BUT THIS WILL BE BRIEF AS ALL OF THE GLOBAL MODELS MAINTAIN THE LARGE POLAR VORTEX OVER NORTH AMERICA THROUGH THE WEEKEND. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY... LAKE HURON NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON UNTIL 1 AM MONDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...BGM LONG TERM....BT AVIATION.....GSS YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 900 PM CST MON JAN 29 2007 .DISCUSSION...LATEST SURFACE ANALYSIS HAS A COLD FRONT DRAPED ACROSS THE OZARKS AND HIGH PRESSURE CENTERED OVER THE FLORIDA PANHANDLE. THE COLD FRONT WILL CONTINUE TO APPROACH OUR CWA TONIGHT AS THE HIGH SHIFTS FARTHER EAST. MID-HIGH LEVEL MOISTURE ASSOCIATED WITH THE SOUTHERN BRANCH OF THE JET CONTINUES PROVIDE CLOUD COVER OVER OUR CWA. LIGHT SOUTHEAST LOW LEVEL FLOW HAS BEGUN TO INCREASE SFC DEW POINTS AS MOST OBS ARE REPORTING DEW POINTS IN THE 20S NOW. OUR AIRMASS WILL CONTINUE TO MOISTEN SLOWLY OVERNIGHT BUT LATEST RUC ISENTROPIC ANALYSIS SUGGESTS THAT IT WILL BE HARD TO GET ANY MEASURABLE PRECIPITATION INTO OUR CWA UNTIL LATER...TOWARD MORNING. HAVE KEPT SLIGHT CHANCE POPS OVERNIGHT IN OUR SOUTHWEST ZONES AND PARISHES BUT BACKED WX GRIDS TO AFTER 3 AM. FCST MORNING LOWS LOOK GOOD BUT HAVE ADJUSTED TEMP CURVES AS CLOUD COVER HAS SLOWED COOLING THIS EVENING. UPDATED ZONES AND GRIDS HAVE BEEN SENT. && .AVIATION... EXPECT THICKENING CLOUDS THROUGH EARLY TUESDAY AS A WEATHER SYSTEM APPROACHES. VFR CONDITIONS ARE STILL EXPECTED TO PREVAIL WITH CEILINGS THIS EVENING AROUND 20KFT LOWERING TO BETWEEN 6KFT AND 8KFT DURING THE DAY. WINDS WILL REMAIN GENERALLY LIGHT AND VARIABLE WITH LIGHT PRECIP POSSIBLE ALONG AND SOUTH OF I-20 TUESDAY. && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ 22 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 907 AM EST MON JAN 29 2007 .SHORT TERM /REST OF TODAY/... LAKE EFFECT SNOW BAND MAKING THE TURN AS WINDS BACK MORE TO WEST/SWLY AHEAD OF NEXT CLIPPER SYSTEM. HAVE ADJUSTED POPS AND WEATHER TO ACCOUNT FOR EXPECTED BAND ORIENTATION FOR THE REST OF TODAY. LATEST GUIDANCE FROM NAM AND RUC IS SUGGESTING THAT THE BAND WILL SWEEP THROUGH ONONDAGA AND MADISON COUNTIES THIS AFTN BEFORE SETTING UP ACROSS ONEIDA COUNTY THIS EVENING. THIS MAY HAVE IMPLICATIONS FOR THE WARNING ACROSS ONONDAGA AND MADISON. WILL WAIT AND SEE HOW THE BAND SETS UP THIS AFTN AND WAIT FOR 12Z SOUNDINGS, THUS CONTINUING ALL WARNINGS BEFORE MAKING DECISIONS ON CHANGES, IF ANY, FOR THE AFTN PACKAGE. && .PREV DISCUSSION... /ISSUED 653 AM EST MON JAN 29 2007/ AVIATION /12Z-12Z/... NORTHWEST FLOW THIS MORNING PRODUCING SCATTERED SNOW SHOWERS AND FLURRIES ACROSS THE FINGER LAKES AND SUSQUEHANNA REGION. AS THE FLOW BACKS THIS AFTERNOON THROUGH THE OVERNIGHT PERIOD, AN ORGANIZED SINGLE BAND OF LAKE EFFECT SNOW WILL IMPACT KSYR/KRME. AT KSYR, MVFR CONDITIONS DUE TO SNOW SHOWERS WILL DETERIORATE LATE THIS AFTERNOON TO IFR THEN LIFR TOWARD EVENING. AFTER 06Z, THE BAND MAY LIFT NORTH OF TERMINAL WITH CONDITIONS IMPROVING TO MVFR. AT KRME, VFR THROUGH EARLY AFTERNOON THEN MVFR WITH CONDITIONS BECOMING IFR TOWARD EVENING THEN LIFR AFTER 02Z. FOR KITH/KBGM, MVFR OCCASIONALLY IFR CONDITIONS THROUGH 15Z DUE TO SNOW SHOWERS AND CIGS. AFTER 15Z, VFR FOR REMAINDER OF PERIOD WITH STRATO CU AROUND 3.5K FT. FOR KAVP/KELM, OCCASIONAL MVFR THROUGH 14Z DUE TO LIGHT SNOW SHOWERS AND CIG RESTRICTIONS. AFTER 15Z, VFR THROUGH THE PERIOD WITH SCT/BKN CLOUDS AT 4K FT. NORTHWEST WINDS 10-12 KNOTS WILL BECOME WESTERLY LATER THIS AFTERNOON THEN SOUTHWEST OVERNIGHT. RRM PREV DISCUSSION... /ISSUED 454 AM EST MON JAN 29 2007/ SHORT TERM /TODAY THROUGH WEDNESDAY/... NORTH TO NW FLOW OF ARCTIC AIR STARTING TO MOVE IN SETTING OFF LAKE EFFECT SNOW. SOME FINGER LAKE ENHANCEMENT COULD BE CAUSING LOW VSBYS IN NARROW BANDS OF MODERATE SNOW. FLOW WILL BEOME BETTER ALIGNED LATER THIS MORNING AFTER A LARGE SHORT WAVE AND SFC LOW PULL FURTHER NE. ALSO IN AREA OF LOW LEVEL CONVERGENCE. WILL CONTINUE WITH THE LES WARNING AS MODELS CONTINUE TO SHOW MANY SIGNS OF A SINGLE BAND SETTING UP THIS AFTERNOON AND CONTINUE INTO THIS EVENING BEFORE WEAKENING. MULTIBANDS THIS MORNING WITH 300 FLOW SHIFTING TO 290 THIS AFTERNOON THEN 280 TONIGHT INTO NORTHERN ONEIDA. MOISTURE INCREASES MIDDAY TO BRING THE INVERSION TO 10K. LAKE EFFECT INSTABILITY GOES TO EXTREME. MODELS ALSO SHOW A LARGE BAND OF OMEGA WITH A CONNECTION TO LAKE HURON. SNOWFALL AMOUNTS COULD EXCEED A FOOT WITH SNOWFALL RATES OF 1 TO 3 INCHES THIS AFTN AND EVE. LATE TONIGHT WEAK WAA WILL WEAKEN THE LAKE EFFECT BUT NOT COMPLETELY SHUT IT DOWN IN NRN ONEIDA. A WEAK SFC LOW AND SHORT WAVE WILL MOVE INTO THE NY AND PA TUESDAY WITH LIGHT SNOW EXPECTED ACROSS MOST OF THE CWA. THE SFC LOW WILL EXIT TUESDAY NIGHT PULLING COLDER AIR BACK INTO TEH CWA. WEAK LAKE EFFECT TUES NGT INTO WED NW FLOW SHIFTS FROM NW TO W SO ANOTHER SINGLE BAND POSSIBLE LATE WED. THIS EVENT WILL BE WEAKER THAN TODAY AND TONIGHT. TAC PREV DISCUSSION... /ISSUED 316 PM EST SUN JAN 28 2007/ LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... THE DEVELOPMENT OF A STRONG HUDSON BAY VORTEX AT 500 MB WILL BRING COLDER THAN NORMAL TEMPERATURES DURING THE LONG RANGE WITH A PATTERN DOMINATED BY SEVERAL WEAK CLIPPER SYSTEMS AND CHCS FOR LAKE EFFECT SNOW SHOWERS. 12Z GFS BACKED OFF ON DEVELOPMENT OF COASTAL SYSTEM AT THE END OF THIS WEEK WITH MAIN CHC FOR SHSN FROM WEAKER LOW MOVING THRU GREAT LAKES AND SECONDARY DEVELOPMENT WEAKER AND FURTHER EAST THAN PREVIOUS RUN. STILL TOO FAR OUT FOR MUCH CERTAINTY FOR EITHER SOLUTION. && .BGM WATCHES/WARNINGS/ADVISORIES... NY...LAKE EFFECT SNOW WARNING UNTIL 7 AM EST TUESDAY FOR NYZ009-018- 036-037. PA...NONE. && $$ ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 940 PM EST TUE JAN 30 2007 .UPDATE... && .SHORT TERM /REST OF TONIGHT/... DRY COLD FRONT THAT WILL BRING THE SECOND ARCTIC SURGE INTO CENTRAL NC IN THE PAST FEW DAYS...IS CURRENTLY LOCATED BETWEEN THE TRIAD AND TRIANGLE. THE WEAK LIFT ASSOCIATED WITH THE FROPA IS PRODUCING A BAND OF BROKEN MID CLOUDS WITH CEILINGS AOA 7.5KFT...WHICH MATCHES UP WELL WITH THE SHALLOW MOIST LAYER BETWEEN 700-800MB SEEN ON THE 00Z/31 GSO RAOB. LIGHT WINDS AND ABSENCE OF CLOUDS HAS ALLOWED TEMPERATURES IN THE NE PIEDMONT AND COASTAL PLAIN TO COOL FASTER THAN OTHER AREAS THIS EVENING...WHILE TEMPERATURES HAVE ACTUALLY ROSE A FEW DEGREES IN THE PAST HOUR OR TWO IN WESTERN AND CENTRAL AREAS WHERE THE CLOUDS AND STRONGER WINDS HAVE PROMOTED MIXING. RUC TIMING OF PUSHING THE COLD FRONT EAST OF THE AREA SHORTLY AFTER 06Z APPEARS REALISTIC...WITH CAA RESULTING IN TEMPERATURES AND DEWPOINTS GRADUALLY FALLING OVERNIGHT. THE STRONGEST CAA WILL OCCUR AFTER DAYBREAK...BEHIND THE VIGOROUS VORT. MAX CURRENTLY DIVING SOUTHEAST INTO THE LOWER OHIO VALLEY. TOUGH CALL ON WHETHER CAA WILL BE STRONG ENOUGH TO RESULT IN UPPER TEENS TO AROUND 20 IN THE NW PIEDMONT AS CURRENT MIN GRIDS INDICATE...AS MIXING WILL BE SUFFICE AS NOT TO ALLOW FURTHER COOLING. WILL RAISE MINS TONIGHT IN THE WEST TO LOWER 20S...OTHERWISE NO OTHER CHANGES EXPECTED. && .PREV DISCUSSION... /ISSUED 230 PM EST TUE JAN 30 2007/ SHORT TERM /TONIGHT THROUGH FRIDAY/... TONIGHT/WEDNESDAY: THE DRY SURFACE COLD FRONT AND ATTENDANT MID LEVEL VORTICITY MAX WILL DROP THROUGH THE AREA LATE TONIGHT... INTRODUCING THE POLAR AIR MASS BENEATH WHICH DEWPOINTS ARE IN THE SINGLE DIGITS TO JUST BELOW ZERO. EXPECT A FEW CLOUDS THIS EVENING THEN MOSTLY CLEAR OVERNIGHT WITH WINDS SWINGING AROUND TO NW. LOWS 19 TO 26. WEDNESDAY SHOULD START OFF WITH PLENTY OF SUNSHINE... THEN MID AND HIGH CLOUDINESS OVER NM AND W TX WILL SWEEP OVER THE AREA... RESULTING IN INCREASED CLOUDS INTO WEDNESDAY EVENING. THICKNESSES INDICATE HIGHS OF 37 TO 43. WEDNESDAY NIGHT THROUGH FRIDAY: ISENTROPIC UPGLIDE BEGINS IN EARNEST LATE WEDNESDAY NIGHT INTO THURSDAY MORNING AS A 40-50 KT 850 MB JET LIFTS OUT OF THE GULF COAST STATES. THE 12Z NAM HAS SPED UP ITS PRECIP ONSET CONSIDERABLY AND IS NOW CLOSER TO THE GFS SOLUTION. HAVE GONE CLOSER TO THE GFS BASED ON ITS BETTER CONSISTENCY. OVERALL PATTERN LOOKS TO BE AN IN SITU DAMMING EVENT WITH A MILLER B CYCLOGENESIS PATTERN. DESPITE THE FACT THAT THE PARENT HIGH CONTAINS AND WILL BE DEPOSITING SOME VERY COLD DRY AIR OVER THE REGION... SINCE IT IS TRANSITORY IN NATURE AND WILL BE SHIFTING OUT INTO THE ATLANTIC... THE LOW LEVEL FEED OF COLD AIR IS UNLIKELY TO BE SUFFICIENTLY LONG LASTING THURSDAY FOR ANY MAJOR ICE ACCUMULATION... AND EXPECT ACCRUAL TO BE SHUT OFF BY LATENT HEAT RELEASE BY THURSDAY AFTERNOON. WILL ISSUE A SPECIAL WEATHER STATEMENT FOR THE WINTRY WEATHER POTENTIAL... BUT HOLD OFF ON SPECIFIC AMOUNTS. GFS PARTIAL THICKNESSES AND FORECAST SOUNDINGS INDICATE AN ONSET OF PRIMARILY SNOW MIXED WITH SLEET IN THE WEST PORTIONS OF CENTRAL NC THURSDAY MORNING... WITH A SMALLER CHANCE OF A WINTRY MIX IN THE EAST. SOUNDINGS START OUT NEAR FREEZING ISOTHERMAL... BUT AT THIS TIME... WITH THE ABSENCE OF STRONG PVA OR JET FORCING... IT LOOKS LIKE PRECIP RATES WILL NOT BE STRONG ENOUGH THURSDAY MORNING TO ALLOW FOR BURSTS OF SNOW THAT COULD LEAD TO NOTABLE ACCUMULATION... ALTHOUGH THIS POTENTIAL CERTAINLY MUST BE WATCHED. THE MID LEVELS THEN WARM RAPIDLY IN THE AFTERNOON... LEADING TO A QUICK TRANSITION TO MOSTLY RAIN EVERYWHERE BY 00Z FRIDAY. HAVE LOWS OF 23-27 WEDNESDAY NIGHT... THEN HAVE A NON-DIURNAL TEMPERATURE TREND... WITH HIGHS THURSDAY 32-39... AND ABOUT 2 DEGREES LOWER FOR LOWS THURSDAY NIGHT. WITH A WEAK SURFACE PATTERN BEHIND THE SPINUP COASTAL LOW AND PLENTY OF RESIDUAL MOISTURE FRIDAY MORNING... EXPECT SLOW CLEARING DURING THE DAY. WILL HAVE HIGHS 45-52... ALTHOUGH IF CLEARING IS MUCH SLOWER FRIDAY... THESE READINGS MAY NEED TO COME DOWN MORE IN LATER FORECASTS. -GIH LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... BROAD L/W TROUGH OVER THE EASTERN U.S. WILL RESULT IN DRY AND CHILLY CONDITIONS ACROSS CENTRAL NC THROUGH THE EXTENDED. MODEL GUIDANCE OFFER VARYING TIMING SOLUTIONS TO THE NEXT SYSTEM IN THE SOUTHERN STREAM. THE ECMWF KEEPS BEST MOISTURE AND LIFT SUPPRESSED WELL SOUTH OF THE AREA. PREVIOUS RUNS OF THE GFS HAD SPREAD MOISTURE WELL NWWD INTO THE COLDER AIR SUN BUT THE RECENT RUN HAS RETRACTED AND HAS DEEPEST MOISTURE S-SE OF AREA. THE CANADIAN PLACES MORE EMPHASIS ON THE NORTHERN STREAM WITH A MILLER A SCENARIO ON SATURDAY WITH LOW TRACKING WEST OF THE MOUNTAINS. ECMWF HAS BEEN CONSISTENT AND WITH THE LATEST GFS TRENDING TOWARD A SIMILAR SCENARIO, PLAN TO KEEP SATURDAY THROUGH TUESDAY PERIOD DRY FOR NOW. GFS ADVECTS BITTERLY COLD AIR INTO REGION DAY 6 AND 7 WITH LOW LEVEL THICKNESSES FALLING INTO THE 1220S BY TUESDAY MORNING. SAW A SIMILAR TREND YESTERDAY FOR MON AND IT HAS SINCE RECOVERED INTO THE 1250S. NEEDLESS...EXPECT MAX TEMPS TO AVERAGE 10-15 DEGREES BELOW NORMAL THROUGH THE PERIOD WITH THE COLDEST WEATHER EXPECTED MON INTO TUE. POTENTIAL FOR MAX TEMPS TO BE COLDER BY DAY6/7 BUT PLENTY OF TIME TO FINE TUNE. -WSS AVIATION /18Z-18Z/... DRY AIR MASS OVER REGION WILL RESULT IN CLEAR SKIES THROUGH 18Z WEDNESDAY. MAY SEE AN INCREASE IN CIRRUS TOWARD 18Z WED AHEAD OF APPROACHING/DEVELOPING SOUTHERN STREAM SYSTEM. REINFORCING SHOT OF COLD DRY AIR WILL OVERSPREAD CENTRAL NC TONIGHT. SURFACE FRONT ASSOCIATED WITH NEW SURGE WILL CROSS REGION BETWEEN 00-05Z. THIS WILL RESULT IN A STEADY NW WIND OVERNIGHT WITH PERIODIC GUSTS AROUND 20KTS. -WSS && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...CBL nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 809 PM CST TUE JAN 30 2007 .UPDATE... MAIN UPDATE CONCERN IS WITH TEMPERATURES. SFC LOW LOCATED OVER YORKTON SASK AT 00Z AND THIS IS RIGHT ON WITH MODEL LOCATION. USING 21Z AND INCOMING 00Z RUC FOR GUIDANCE SHOWS LOW DROPPING SOUTHEAST TO NEAR THE GRAND FORKS AREA AROUND 12Z. THIS ALSO FITS THE INCOMING 00Z NAM GUIDANCE AS WELL. CANADIAN RADARS AND METARS SHOW LIGHT SNOW NORTHEAST OF SFC LOW CENTER...WITH ANOTHER AREA OF SNOW FURTHER WEST ASSOC WITH VORT MAX AND 500 MB HEIGHT FALL CENTER IN SE ALBERTA/SW SASK. THE VORT OUT WEST WILL DROP INTO ERN MT AND SW ND DURING THE NEXT 12 HOURS AND NOT GREATLY AFFECT OUR AREA. LIGHT SNOW ASSOC WITH SFC LOW WILL MOVE SOUTHEAST AND LIKELY AFFECT NORTHEAST ND AFTER 08Z AND THEN SPREAD THROUGH THE FCST AREA DURING THE PRE-DAWN HOURS THRU MID MORNING ON WEDNESDAY. DID SLIGHT POP TIMING RE-ADJUSTMENTS FOR THIS THINKING. AS FOR TEMPS...SOME DROP SEEN IN THE SOUTHEASTERN FCST AREA WITH WADENA AT ZERO...BUT OTHERWISE SOUTHWEST WIND AND THICKENING HIGH CLOUDS HOLDING TEMPS UP WITH ONLY MINIMAL FALL SINCE 22Z. WITH THICKER CLOUDS TO CONTINUE TO OVERSPREAD THE AREA WOULD EXPECT LITTLE CHANGE IN TEMPS TONIGHT AND MIGHT RISE IN SPOTS. DID ADJUST TEMP GRIDDS TONIGHT THRU 18Z WED FOR THIS THINKING. && .PREV DISCUSSION... /ISSUED 228 PM CST TUE JAN 30 2007/ SHORT TERM... CURRENTLY...ONLY HIGH CLOUDINESS COMBINED WITH SOME MIXING IS ALLOWING DECENT TEMPERATURE RECOVERY THIS AFTERNOON AS A MORE SUBSTANTIAL MID LEVEL DECK MOVES FROM MONTANA/SASKATCHEWAN INTO NW ND AHEAD OF VORT/SHORT WAVE IN CENTRAL SASKATCHEWAN. WITH RESPECT TO GUIDANCE...WILL TEND TOWARDS THE GFS AND ITS PROGRESSIVE MOVEMENT OF SYSTEMS AND ITS RECENT CONSISTENCY. TONIGHT/WEDNESDAY...FIRST OF TWO CLIPPERS DESCENDS THIS EVENING INTO NORTHERN FORECAST AREA DURING THE OVERNIGHT. FCST SOUNDINGS INDICATE ENOUGH MOISTURE TO GO WITH AT LEAST CHANCE POPS PROGRESSING FROM NORTH TO SOUTH. WARM ADVECTION AHEAD OF SYSTEM ALONG WITH THICKENING CLOUD AND SW WIND MAY YIELD NON- DIURNAL TEMP TREND OVERNIGHT...THIS CAN BE REFINED BY THE EVENING CREW MEMBERS. DON`T SEE MUCH COLD PUNCH BEHIND THIS FIRST SYSTEM SO MINIMAL PROBLEMS WITH BLOWING/DRIFTING ARE ANTICIPATED AT THIS TIME. HIGH PRESSURE BRIEFLY NUDGES IN BEHIND DEPARTING CLIPPER LATER WEDNESDAY...WHICH WILL BE SHORT LIVED AS THE MORE POTENT SYSTEM LURKING TO THE NORTH TAKES AIM ON THE FORECAST AREA FOR THURSDAY. THURSDAY/FRIDAY...NEXT SYSTEM MORE LOADED IN TERMS OF LIFT...GRADIENT AND DEEP LAYERED MOISTURE. THESE FACTORS COMPUTE TO LIKELY POPS THURSDAY AFTERNOON FOLLOWED BY ROBUST SURGE OF COLD AIR ADVECTION THURSDAY NIGHT. NORTHERLY WINDS WITH SOLID LINKAGE (ALBEIT PERHAPS NOT AS STRONG AS PRIOR RUNS) WILL PRODUCE VENTURI EFFECT FOR THE VALLEY. ALL IN ALL THIS INCREASES THE POTENTIAL FOR A BLOWING SNOW/VERY LOW VISIBILITY EVENT PRIMARILY OVER OPEN COUNTRY...H925 LEVEL WINDS CLOSE TO 30 KTS LIKELY TO TRANSLATE DOWN TO 20-25 KTS WITH HIGHER GUSTS AT SURFACE...WITH AREA OF MAXIMUM PRESSURE RISES LOOKING NOW TO BE OVER CENTRAL ND. SATURATED COLUMN TO AT LEAST 600 MB SHOULD PERSIST ON FRIDAY...WINDS DIMINISH...BUT EVEN WITH LACK OF OTHER PARAMETERS...MOISTURE WILL BE SUFFICIENT TO KEEP SNOW SHOWER ACTIVITY ALIVE. LONG TERM (SAT THROUGH TUE)...LONG RANGE MODELS REMAIN IN PRETTY GOOD AGREEMENT FOR EXTENDED FORECAST. 500MB TROF AND SURFACE LOW START MOVING E OF THE AREA ON SAT...KEEPING A NW FLOW OVER THE REGION THROUGH THE WEEKEND. VERY COLD TEMPERATURES WITH WIND WILL CONTINUE ON SAT...UNTIL THE SURFACE HIGH PRESSURE SYSTEM BUILDS IN FOR SUN. THEN...THE COLD TEMPERATURES REMAIN...BUT WITH LESS WIND FOR SUN AND SUN NIGHT. ON MON...THE SURFACE HIGH PRESSURE STARTS MOVING E AND S-SE RETURN FLOW SETS UP...KEEPING THE COLD AIR MASS OVER THE REGION FOR ONE MORE DAY. AS FAR AS TEMPERATURES...KEPT MUCH BELOW NORMAL THROUGH THE EXTENDED FORECAST. FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. $$ RIDDLE/ nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1012 PM EST TUE JAN 30 2007 .SHORT TERM /THROUGH TUESDAY NIGHT/... WILL SEND OUT A QUICK...LATE EVENING ZONE UPDATE TO FRESHEN UP THE WORDING FOR SNOW SHOWERS ACROSS THE REGION. ARCTIC FRONT HAS PUSHED EAST OF THE SUSI VALLEY...TAKING THE HEAVY SQUALLS WITH IT. WEAKENING MID LEVEL DEFORMATION SNOWS ACROSS THE NCENT MTNS WILL BRING ANOTHER INCH OR TWO TO SOME LOCATIONS OVER THE NEXT FEW HOURS WITHIN THE SNOW ADVISORY...WHICH SET TO EXPIRE AT MIDNIGHT EST. PERSISTENT LAKE EFFECT/OROGRAPHIC SNOWS ACROSS THE NW MTNS AND LAUREL HIGHLANDS RESPECTIVELY WILL CONTINUE TO ACCUMULATE A FEW MORE INCHES OVERNIGHT...SO NO CHANGES TO THE LAKE EFFECT/SNOW ADVISORIES FOR THOSE AREAS. ELSEWHERE...EXPECT FLURRIES AND A BRIEF HEAVIER SNOW SHOWER OVERNIGHT AS THE PRIMARY 700-500 HPA THERMAL TROUGH MOVES SE FROM THE GLAKES. ACCUMULATIONS WILL BE LESS THAN AN INCH ACROSS THE CENTRAL RIDGE AND VALLEY REGION. OVC LAYER WILL BREAK UP AFTER MIDNIGHT ACROSS THE LOWER SUSQ VALLEY AS DRIER DEWPOINTS IN THE UPPER SINGLE DIGITS ADVECT EAST VIA A DOWNSLOPE LLVL FLOW. TRIMMED HOURLY AND MIN TEMPS OVERNIGHT BY 2-4 DEG F IN MANY LOCATIONS. && .PREV DISCUSSION... /ISSUED 728 PM EST TUE JAN 30 2007/ SHORT TERM /THROUGH TONIGHT/... AREA OF INSTABILITY WITH TOTAL TOTALS NEAR 50 CROSSING THE SUSQ VALLEY...ALONG WITH A RATHER STRONG...ALBEIT COMPACT UPPER SHORT WAVE MOVE EAST OVER THE NCENT MTNS WILL BRING NUMEROUS SNOW SHOWERS AND LOCALLY HEAVY SNOW SQUALLS EARLY TONIGHT. ISSUED A SNOW ADVISORY ACROSS THE NCENT MTNS THROUGH MIDNIGHT WHERE A MESO-B MID LVL DEFORMATION ZONE AND CORRESPONDING EAST/WEST BELT OF ENHANCED 850-700 HPA OMEGA WILL LEAD TO SEVERAL INCHES OF NEW SNOW. SNOW SHOWERS AND SQUALLS WILL DIMINISH TO SCATTERED FLURRIES ACROSS THE CENTRAL VALLEYS AND SUSQ RIVER VALLEY LATE THIS EVENING. PREV DISCUSSION... /ISSUED 325 PM EST TUE JAN 30 2007/ SHORT TERM /TONIGHT THROUGH WEDNESDAY/... MESO ANAL SHOWS SFC LOW JUST WEST OF BFD AT 18Z...WITH THE COLD FRONT MOVING THRU SWRN PA. RUC SHOWS A POCKET OF RELATIVELY UNSTABLE AIR...LOW-MID LEVEL LAPSE RATES IN EXCESS OF 6C/KM AND T-TOTALS TOPPING 50...HELPING TRIGGER THE CURRENT SNOW SHOWERS AND SQUALLS MOVING ACROSS THE AREA. THE BEST FORCING/INSTABILITY STARTS TO WANE AFTER ABOUT 21Z ACCORDING TO SHORT TERM GUIDANCE...WITH THE FRONT EXPECTED TO CLEAR MY EASTERN ZONES BY 00Z. AFTER THE FROPA...WE WILL TRANSITION INTO A MORE TYPICAL NW FLOW REGIME WITH LAKE EFFECT AND OROGRAPHICALLY FORCED SNOWS IN THE WEST...AND ACTIVITY TAPERING OFF TO JUST SCATTERED SNOW SHOWERS AND FLURRIES THE FURTHER DOWNWIND OF THE LAKES AND LAURELS ONE GETS. ONLY CONCERN IS A HINT IN THE MODELS THAT THE UPPER-AIR PORTION OF THE OCCLUDED FRONT HANGS TOUGH FOR A TIME INTO NW PA...ENHANCING THE CONVERGENCE THERE INTO THE EVENING. THIS SHOWS UP AS A WELL DEFINED THERMAL RIDGE UP THRU ABOUT 850MB IN ALL THE SHORT RANGE GUIDANCE. THEY SHIFT THIS EAST OF THE AREA AFTER 03Z. WEDNESDAY WILL SEE CONDITIONS IMPROVING AS INVERSION HEIGHTS LOWER THROUGHOUT THE DAY. THE BEST CHANCE OF LINGERING SNOW WILL BE OVER WESTERN HIGH TERRAIN. ELSEWHERE WE SHUD SEE LITTLE MORE THAN FLURRIES. LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... UPPER TROFFING OVER EASTERN NORTH AMERICA LOOKS TO DOMINATE THE LONG TERM PERIOD. THIS WILL LEAD TO NEAR TO BELOW NORMAL TEMPERATURES EARLY IN THE PERIOD AND POSSIBLY SIGNIFICANTLY BELOW NORMAL TEMPERATURES LATE IN THE PERIOD. MOST OF THE PERIOD LOOKS DRY...BUT TWO OPPORTUNITIES FOR PCPN STAND OUT. A WEATHER SYSTEM THAT HAS BEEN ADVERTISED FOR SEVERAL DAYS TO AFFECT THE REGION LATE THURSDAY INTO FRIDAY CONTINUES TO LOOK COMPLEX...WITH VARYING RUN TO RUN MODEL SOLUTIONS. A SOUTHERN STREAM TROF IS FORECAST TO INDUCE CYCLOGENESIS OVER THE SOUTHEAST U.S. THURSDAY NIGHT WITH A NORTHERN STREAM TROF FORECAST TO SWING THROUGH THE REGION LATER FRIDAY. MUCH YET DEPENDS ON THE TRACK OF THE COASTAL LOW AND ANY PHASING THAT MAY TAKE PLACE BETWEEN THE TWO STREAMS. AT THIS TIME...THERE IS A HIGH PROBABILITY OF MEASURABLE ACROSS ALL OF THE CWA...WITH POTENTIAL FOR A SEVERAL INCH SNOWFALL ACROSS THE REGION...EVEN THE LOWER SUSQUEHANNA VALLEY...WHERE SNOWFALL SO FAR THIS SEASON IS LESS THAN AN INCH TOTAL. A PRONOUNCED ARCTIC TROF IS FORECAST TO MOVE THROUGH THE FORECAST AREA ON MONDAY...POTENTIALLY BRINGING IN THE COLDEST AIR YET THIS WINTER. AVIATION /20Z-18Z/... THE AFTERNOON`S WIDESPREAD IFR CAUSED BY THE SHORTWAVE AND SNOW SHOWERS SHUD BEGIN TO IMPROVE IN MOST AREAS THIS EVENING AS THE UPPER TROF MOVES EAST OF THE REGION AND A WEST-NORTHWEST FLOW DEVELOPS. LIKE A BROKEN RECORD THOUGH...JST/BFD WILL NOT SHARE IN THE IMPROVEMENT AS UPSLOPE AND PROXIMITY TO LAKE ERIE CONSPIRE TO KEEP BOTH TERMINALS MAINLY DOWN BELOW 3000/3 WITH FREQUENT SNOW SHOWERS BRINGING EVEN LOWER CONDITIONS. WILL PROB SEE AOO/UNV/IPT IMPROVE TO MVFR CEILINGS AND MOSTLY UNLIMITED VIS WITH ONLY OCNL SNOW SHOWERS BRINGING BRIEFLY REDUCED VIS AFTER 00Z...WITH VFR DEVELOPING SLOWLY LATER TONIGHT INTO EARLY WED MORNING. STILL A QUESTION AS TO WHETHER THE FAR SERN TERMINALS WILL SEE MUCH INCLEMENT WX AT ALL AS THE SYSTEM IS ALREADY MOISTURE STARVED AND DOWN-SLOPING FLOW WILL ONLY HELP IN MAKING MUCH OF THE SNOW SHOWER ACTIVITY DRY UP BEFORE IT MAKES IT INTO THE LOWER SUSQ VALLEY. THINK THERE IS A CHC OF SNOW SHOWERS AND BRIEFLY LOWER CONDITIONS THRU THE EVENING...BUT AFTER THAT CIG/VIS SHUD NOT POSE MUCH OF A CHALLENGE THERE. && .CTP WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST WEDNESDAY FOR PAZ004- 005-010. SNOW ADVISORY UNTIL 10 AM EST WEDNESDAY FOR PAZ024-033. SNOW ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR PAZ041-042-046- 053. && $$ SHORT TERM...LAMBERT pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 728 PM EST TUE JAN 30 2007 .SHORT TERM /THROUGH TONIGHT/... AREA OF INSTABILITY WITH TOTAL TOTALS NEAR 50 CROSSING THE SUSQ VALLEY...ALONG WITH A RATHER STRONG...ALBEIT COMPACT UPPER SHORT WAVE MOVE EAST OVER THE NCENT MTNS WILL BRING NUMEROUS SNOW SHOWERS AND LOCALLY HEAVY SNOW SQUALLS EARLY TONIGHT. ISSUED A SNOW ADVISORY ACROSS THE NCENT MTNS THROUGH MIDNIGHT WHERE A MESO-B MID LVL DEFORMATION ZONE AND CORRESPONDING EAST/WEST BELT OF ENHANCED 850-700 HPA OMEGA WILL LEAD TO SEVERAL INCHES OF NEW SNOW. SNOW SHOWERS AND SQUALLS WILL DIMINISH TO SCATTERED FLURRIES ACROSS THE CENTRAL VALLEYS AND SUSQ RIVER VALLEY LATE THIS EVENING. && .PREV DISCUSSION... /ISSUED 325 PM EST TUE JAN 30 2007/ SHORT TERM /TONIGHT THROUGH WEDNESDAY/... MESO ANAL SHOWS SFC LOW JUST WEST OF BFD AT 18Z...WITH THE COLD FRONT MOVING THRU SWRN PA. RUC SHOWS A POCKET OF RELATIVELY UNSTABLE AIR...LOW-MID LEVEL LAPSE RATES IN EXCESS OF 6C/KM AND T-TOTALS TOPPING 50...HELPING TRIGGER THE CURRENT SNOW SHOWERS AND SQUALLS MOVING ACROSS THE AREA. THE BEST FORCING/INSTABILITY STARTS TO WANE AFTER ABOUT 21Z ACCORDING TO SHORT TERM GUIDANCE...WITH THE FRONT EXPECTED TO CLEAR MY EASTERN ZONES BY 00Z. AFTER THE FROPA...WE WILL TRANSITION INTO A MORE TYPICAL NW FLOW REGIME WITH LAKE EFFECT AND OROGRAPHICALLY FORCED SNOWS IN THE WEST...AND ACTIVITY TAPERING OFF TO JUST SCATTERED SNOW SHOWERS AND FLURRIES THE FURTHER DOWNWIND OF THE LAKES AND LAURELS ONE GETS. ONLY CONCERN IS A HINT IN THE MODELS THAT THE UPPER-AIR PORTION OF THE OCCLUDED FRONT HANGS TOUGH FOR A TIME INTO NW PA...ENHANCING THE CONVERGENCE THERE INTO THE EVENING. THIS SHOWS UP AS A WELL DEFINED THERMAL RIDGE UP THRU ABOUT 850MB IN ALL THE SHORT RANGE GUIDANCE. THEY SHIFT THIS EAST OF THE AREA AFTER 03Z. WEDNESDAY WILL SEE CONDITIONS IMPROVING AS INVERSION HEIGHTS LOWER THROUGHOUT THE DAY. THE BEST CHANCE OF LINGERING SNOW WILL BE OVER WESTERN HIGH TERRAIN. ELSEWHERE WE SHUD SEE LITTLE MORE THAN FLURRIES. LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... UPPER TROFFING OVER EASTERN NORTH AMERICA LOOKS TO DOMINATE THE LONG TERM PERIOD. THIS WILL LEAD TO NEAR TO BELOW NORMAL TEMPERATURES EARLY IN THE PERIOD AND POSSIBLY SIGNIFICANTLY BELOW NORMAL TEMPERATURES LATE IN THE PERIOD. MOST OF THE PERIOD LOOKS DRY...BUT TWO OPPORTUNITIES FOR PCPN STAND OUT. A WEATHER SYSTEM THAT HAS BEEN ADVERTISED FOR SEVERAL DAYS TO AFFECT THE REGION LATE THURSDAY INTO FRIDAY CONTINUES TO LOOK COMPLEX...WITH VARYING RUN TO RUN MODEL SOLUTIONS. A SOUTHERN STREAM TROF IS FORECAST TO INDUCE CYCLOGENESIS OVER THE SOUTHEAST U.S. THURSDAY NIGHT WITH A NORTHERN STREAM TROF FORECAST TO SWING THROUGH THE REGION LATER FRIDAY. MUCH YET DEPENDS ON THE TRACK OF THE COASTAL LOW AND ANY PHASING THAT MAY TAKE PLACE BETWEEN THE TWO STREAMS. AT THIS TIME...THERE IS A HIGH PROBABILITY OF MEASURABLE ACROSS ALL OF THE CWA...WITH POTENTIAL FOR A SEVERAL INCH SNOWFALL ACROSS THE REGION...EVEN THE LOWER SUSQUEHANNA VALLEY...WHERE SNOWFALL SO FAR THIS SEASON IS LESS THAN AN INCH TOTAL. A PRONOUNCED ARCTIC TROF IS FORECAST TO MOVE THROUGH THE FORECAST AREA ON MONDAY...POTENTIALLY BRINGING IN THE COLDEST AIR YET THIS WINTER. AVIATION /20Z-18Z/... THE AFTERNOON`S WIDESPREAD IFR CAUSED BY THE SHORTWAVE AND SNOW SHOWERS SHUD BEGIN TO IMPROVE IN MOST AREAS THIS EVENING AS THE UPPER TROF MOVES EAST OF THE REGION AND A WEST-NORTHWEST FLOW DEVELOPS. LIKE A BROKEN RECORD THOUGH...JST/BFD WILL NOT SHARE IN THE IMPROVEMENT AS UPSLOPE AND PROXIMITY TO LAKE ERIE CONSPIRE TO KEEP BOTH TERMINALS MAINLY DOWN BELOW 3000/3 WITH FREQUENT SNOW SHOWERS BRINGING EVEN LOWER CONDITIONS. WILL PROB SEE AOO/UNV/IPT IMPROVE TO MVFR CEILINGS AND MOSTLY UNLIMITED VIS WITH ONLY OCNL SNOW SHOWERS BRINGING BRIEFLY REDUCED VIS AFTER 00Z...WITH VFR DEVELOPING SLOWLY LATER TONIGHT INTO EARLY WED MORNING. STILL A QUESTION AS TO WHETHER THE FAR SERN TERMINALS WILL SEE MUCH INCLEMENT WX AT ALL AS THE SYSTEM IS ALREADY MOISTURE STARVED AND DOWN-SLOPING FLOW WILL ONLY HELP IN MAKING MUCH OF THE SNOW SHOWER ACTIVITY DRY UP BEFORE IT MAKES IT INTO THE LOWER SUSQ VALLEY. THINK THERE IS A CHC OF SNOW SHOWERS AND BRIEFLY LOWER CONDITIONS THRU THE EVENING...BUT AFTER THAT CIG/VIS SHUD NOT POSE MUCH OF A CHALLENGE THERE. && .CTP WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST WEDNESDAY FOR PAZ004- 005-010. SNOW ADVISORY UNTIL 10 AM EST WEDNESDAY FOR PAZ024-033. SNOW ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR PAZ011-012-041- 042-046-053. && $$ SHORT TERM...LAMBERT pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 914 PM CST TUE JAN 30 2007 .UPDATE... LATEST SATELLITE AND WSR-88D DATA INDICATE THE POTENTIAL FOR SHOWERS ACROSS THE NORTHERN BIG COUNTRY...WITH THE BEST RADAR RETURN CURRENTLY OVER HASKELL COUNTY AND THROCKMORTON COUNTY. SURFACE WINDS ACROSS WEST CENTRAL TEXAS REMAIN MAINLY NORTHEAST. HOWEVER...LATEST RUC DATA INDICATE WINDS WILL BECOME SOUTHEAST OVERNIGHT. THUS...CURRENT FORECAST LOOKS ON TRACK. 23/HUBER && .PREV DISCUSSION... /ISSUED 533 PM CST TUE JAN 30 2007/ AVIATION... COLD FRONT HAS MOVED SOUTH OF WEST CENTRAL TEXAS...WITH SURFACE NORTH TO NORTHEAST OF AROUND 10 KNOTS. SURFACE WINDS WILL RETURN TO SOUTHERLY AT 10 TO 15 KNOTS ON WEDNESDAY. AREAS OF MVFR CIGS OF BKN010-020 ARE EXPECTED ACROSS WEST CENTRAL TEXAS AFTER 31/09Z ..WITH MVFR CIGS BECOMING MORE WIDESPREAD AFTER 31/13Z. SCT SHRA WILL DEVELOP ACROSS WEST CENTRAL TEXAS AFTER 31/09Z...POSSIBLY MIXED WITH SLEET AND SNOW ACROSS THE BIG COUNTRY. 21 PREV DISCUSSION... /ISSUED 327 PM CST TUE JAN 30 2007/ SHORT TERM... UPPER LEVEL CLOUDS WERE REDEVELOPING FROM THE WEST WITH UPSLOPE FLOW BEHIND COLD FRONT THIS AFTERNOON (AT LEAST SOUTH OF INTERSTATE 20). WATER VAPOR LOOP INDICATED UPPER LEVEL LOW WAS OVER SOUTHERN CALIFORNIA...WITH SOME LIFT INDICATED AHEAD OF THE SYSTEM OVER ARIZONA AND NEW MEXICO. MID LEVEL MOISTURE INCREASES LATE TONIGHT AS UPPER LEVEL LOW SHEARS OUT AND MOVES TOWARD THE REGION...AND RIDING OVER THE COLD FRONT. MAY SEE SOME LIGHT PRECIPITATION TOWARD MORNING. GFS FORECAST SOUNDING INDICATE THIS TO BE SNOW OR SNOW/RAIN MIXTURE IN THE BIG COUNTRY...IF IT OCCURS. DO NOT ANTICIPATED ACCUMULATIONS. WENT A LITTLE LOWER ON TEMPERATURES (FROM MAV GUIDANCE) ACROSS THE BIG COUNTRY WHERE IT MAY TAKE A LITTLE LONGER FOR CLOUD COVER TO COME IN TONIGHT. LONG TERM... BEST SHORTWAVE/LIFT COMES IN WEDNESDAY TONIGHT. TEMPERATURES PROFILES INDICATE THIS TO BE MAINLY RAIN...THROUGH ITS POSSIBLE SOME SLEET MAY OCCUR IN NORTHERN SECTIONS OF THE BIG COUNTRY. RAIN CHANCES TAPER OFF THURSDAY MORNING. NEXT COLD FRONT COMES IN ON FRIDAY...KEEPING TEMPERATURES ON THE COOL SIDE THIS WEEKEND. MOISTURE TOO SHALLOW FOR ANY SIGNIFICANT RAIN THIS WEEKEND...THOUGH CANT RULE OUT A SPRINKLE OR TWO. ECMWF DIFFER IN HANDLING ANOTHER COLD FRONT NEXT WEEK. ECMWF HAS COLD FRONT MONDAY...WHICH BUILDS IN VERY STRONGLY THROUGH TUESDAY. THE GFS PUSHES MOST OF THE COLD AIR TO THE EAST ON MONDAY...WITH ONLY A WEAKER COLD FRONT. IT THEN BRINGS WEST CENTRAL TEXAS IN SOUTHERLY WARM ADVECTION TUESDAY...BEFORE A SECOND STRONG COLD FRONT MOVES IN TUESDAY NIGHT. WILL GO WITH THE COLDER ECMWF SOLUTION FOR NOW...AS A LOT OF TIMES FRONT GETS CHANNELS AGAINST THE ROCKY MOUNTAINS. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 31 48 37 48 / 20 30 50 20 SAN ANGELO 34 51 40 55 / 20 20 50 20 JUNCTION 37 49 44 60 / 20 20 50 20 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/HUBER tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 1257 PM CST TUE JAN 30 2007 .DISCUSSION...SFC LOW OVER NWRN GULF CONTINUES TO MOVE AWAY WITH HIGH PRESSURE BUILDING INTO THE REGION. NRLY LLVL WINDS COMBINED WITH SW WINDS ALOFT MAINTAINING MOSTLY CLOUDY SKIES TODAY. SFC WINDS WILL VEER TO THE SE THEN S WED AS A SFC LOW MOVES OUT OF THE SIERRA MADRE ORIENTAL. THE APPROACHING LOW WILL COMBINE WITH INCREASED LLVL MOISTURE PRODUCE MOSTLY CLOUDY TO CLOUDY SKIES...SCHC POPS...AREAS OF FG AND PATCHY DZ. THIS PATTERN WILL CONTINUE UNTIL SFC LOW MOVES E ALLOWING DRIER AIR TO ADVECT INTO CWA ON NW WINDS. A SECONDARY FRONT PUSHES THROUGH SAT BEFORE STALLING ACROSS OR JUST S OF CWA. THE PROXIMITY OF THE FRONT WILL COMBINE WITH WEAK COASTAL TROUGHING TO PRODUCE CHC POPS AND DZ THROUGH THE WEEKEND. CONDITIONS IMPROVE EARLY NEXT WEEK AS UPPER LEVEL RIDGE BUILDS INTO THE REGION. && .MARINE...SURFACE WINDS AT BUOY020 HAVE TAKEN A JUMP IN THE LAST HOUR REACHING TO NEAR 14 KTS WHICH IS LIKELY DUE TO THE FORMATION OF THE MARINE SURFACE LOW OVER THE NORTHWESTERN GULF OF MEX. A BEST GUESS FOR THE LOCATION OF THE SURFACE LOW UTILIZING SURFACE OBS...BUOY DATA AND THE LATEST RUC MSL FIELDS SEEMS TO BE ABOUT HALFWAY BETWEEN BUOY019 AND BUOY002. THE CLOSE PROXIMITY OF THIS LOW WILL LIKELY TIGHTEN THE PGF OFFSHORE TO PUSH WINDS TO NEAR SCA LEVELS TONIGHT. THIS LOOKS REASONABLE AND WILL ISSUE AN SCA FOR THE OFFSHORE WATERS FOR THE EVENING AND OVERNIGHT HOURS. AS THIS SURFACE LOW MOVES FURTHER AWAY FROM THE LOWER TX COASTLINE...THE PGF WILL RELAX SOME TOMORROW ALLOWING THE WINDS AND SEAS TO WEAKEN INTO WEDNESDAY NIGHT AND EARLY THURSDAY. HOWEVER...ANOTHER PUSH OF STRONGER NORTHERLY SURFACE WINDS WILL BEGIN LATE FRIDAY WITH STRONG NORTHEAST WINDS CONTINUING INTO SAT AND SUN. THE PGF WILL WEAKEN ONCE AGAIN ACROSS THE AREA ON MON INTO TUES AS THE CENTER OF THE STRONG SURFACE HIGH OVER THE EASTERN U.S. LIFTS OUT TO THE EAST AND SURFACE TROFFING ACROSS THE GULF OF MEX DIMINISHES. GWW GUIDANCE KEEPS 2 TO 3 METER SWELLS IN PLACE FOR THE OFFSHORE AREAS LATE SAT AND SUN AND IN THE 1 TO 2 METER RANGE FOR MON AND TUES. THIS LOOKS REASONABLE AND IS PRETTY WELL REFLECTED IN THE CURRENT CWF WORDING. && .AVIATION...VSBL SATELLITE IMAGERY SHOWS PRETTY EXTENSIVE AND THICK LOW LEVEL SC IN PLACE OVER THE REGION. ACCORDINGLY...LOW CEILINGS WILL LIKELY HOLD ON THROUGHOUT THE DAY. FWC/MAV AND MET VSBY GUIDANCE ALL INDICATE THAT FOG WILL LIKELY REFORM LATER TONIGHT WITH THE CONTINUED NORTHERLY SURFACE FLOW CONTINUING AND THE FAIRLY NARROW TEMP/DEWPOINT SPREADS PERSISTING INTO THE OVERNIGHT PERIOD. IFR/LIFR CONDITIONS WILL BE POSSIBLE AGAIN TONIGHT FOR ALL OF THE LOWER RGV AIRPORTS. INCREASED LOW LEVEL MIXING TOMORROW WILL GRADUALLY IMPROVE CEILINGS AND VSBYS ONCE AGAIN. HOWEVER...THE CEILINGS WILL LIKELY REMAIN SOMEWHAT LOW ONCE AGAIN ON WED. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 55 67 59 71 57 / 20 20 20 20 10 BROWNSVILLE 54 67 58 75 55 / 20 20 20 20 10 HARLINGEN 52 67 57 76 52 / 20 20 20 20 10 MCALLEN 53 64 56 75 53 / 20 20 20 20 10 RIO GRANDE CITY 53 61 53 76 52 / 20 20 20 10 10 SOUTH PADRE ISLAND 55 67 59 71 57 / 20 20 20 20 10 && .BRO WATCHES/WARNINGS/ADVISORIES... SCA GMZ 150-155-170-175 AFTER 6 PM CST. && $$ THIS PRODUCT IS ALSO AVAILABLE ON OUR INTERNET WEB PAGE AT: HTTP://WWW.SRH.NOAA.GOV/BRO 55/60/VEGA tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 935 PM CST MON JAN 29 2007 .UPDATE... THE COLD FRONT IS CURRENTLY MOVING INTO THE NORTHWEST SECTIONS OF NORTH TEXAS. THE FRONT WILL SLIDE THROUGH THE ENTIRE REGION BY SUNRISE TUESDAY. WE HAVE MADE SOME ADJUSTMENTS TO THE POSITION AND SPEED OF THE COLD FRONT BASED ON TRENDS OVER THE LAST FEW HOURS. THE SLOWER MOVEMENT OF THE COLD FRONT WILL ALSO LIMIT THE POTENTIAL FOR LIGHT SHOWERS IN THE SOUTHEAST ZONES OVERNIGHT. THEREFORE...WE WILL LOWER POPS IN THE SOUTHEAST TO 20 PERCENT. THE LATEST NAM MODEL SOLUTION IS KEEPING NORTH TEXAS DRY THROUGH SUNRISE WEDNESDAY AND DOES NOT INCREASE THE LIFT OVER NORTH TEXAS UNTIL WEDNESDAY AFTERNOON. NAM MODEL SOUNDINGS ALSO SHOW THAT MOST IF NOT ALL PRECIPITATION WEDNESDAY WOULD FALL AS RAIN. FOR NOW WE WILL WAIT FOR SOME AGREEMENT FROM THE OTHER MODELS BEFORE ADJUSTING/REMOVING THE MENTION OF A WINTRY MIX OF PRECIPITATION WEDNESDAY AND WEDNESDAY NIGHT. 79 && .AVIATION ... MODELS GIVING MIXED SIGNALS ON MOISTURE IN THE METRO DFW TRACON AREA. STRATUS DECK OVR SOUTH CENTRAL TX IS STILL MOVG TOWARD NE TEXAS. MAV AND RUC IN FAIRLY CLOSE AGREEMENT WITH CEILINGS AROUND 040-050 THRU 06Z. CDFNT MOVG ACRS SW OK MOVING AROUND 10 KTS. TIMING LOOKS GOOD ARND 06/07Z. LAMP IS FAR TOO AGGRESSIVE IN TIMING OF FRONTAL PASSAGE SO HAVE SLOWED TIMING TO THE 06-07Z TIMEFRAME. 50 && ...WINTRY MIX POSSIBLE FOR THE WESTERN AND NORTHERN AREAS WEDNESDAY THROUGH THURSDAY... .DISCUSSION... COMPLICATED FORECAST FOR THE NEXT SEVERAL DAYS...BUT WE DO NOT ANTICIPATE A MAJOR WINTER EVENT. JUST A WINTRY MIX AT TIMES WITH LITTLE OR NO ICE ACCUMULATION. UPPER LOW OFF THE CALIFORNIA COAST WILL DRIFT INLAND BY TUESDAY NIGHT...WEAKEN INTO AN OPEN WAVE THEN MERGE WITH STRONG SHORT WAVE COMING OUT OF CANADA AND TRANSLATE ACROSS THE SOUTHERN PLAINS WEDNESDAY NIGHT. SEVERAL MORE UPSTREAM SHORT WAVES WILL MOVE INTO THE MEAN TROUGH ON THURSDAY AND THIS WEEKEND...STRENGTHENING THE LONG WAVE TROUGH ACROSS NOAM AND AIDING THE SURGE OF ARCTIC AIR SOUTHWARD. WE CONTINUE TO FEEL THAN MODELS DO NOT HAVE A GOOD HANDLE ON THE ARCTIC SURGES...THUS MOS TEMPS SEEM TOO WARM...ESPECIALLY FOR THIS WEEKEND AND EARLY NEXT WEEK. THERE WILL BE A CHANCE OF RAIN OVER THE SOUTHERN CWA TONIGHT AS A SURFACE WAVE FORMS ALONG THE TEXAS COAST AND MOVES EAST AHEAD OF THE FIRST COLD FRONT ARRIVING OVERNIGHT. COLD AIR SETTLES OVER NORTH TEXAS WEDNESDAY AS AN IMPULSE FROM THE WEST NEARS AND INCREASES PRECIPITATION CHANCES DURING THE DAY AND INTO THURSDAY. THERE WILL BE SOME DRY AIR ALOFT OVER THE WEST THAT MIGRATES NORTH WITH TIME DUE TO WARM AIR ADVECTION...THUS WET BULBING EFFECTS SHOULD PRODUCE SOME SLEET OVER THE WEST AND NORTH COUNTIES WEDNESDAY AND WEDNESDAY NIGHT. ALSO...LIQUID RAIN COULD FALL INTO SUB-FREEZING AIR IN THE EARLY MORNING HOURS...THUS HAVE ADDED SOME FREEZING RAIN. THE PRECIPITATION PROCESS WILL DIMINISH AS SHORT WAVE ENERGY MOVES EAST LATE THURSDAY NIGHT. ANOTHER ARCTIC COLD FRONT ARRIVES FRIDAY. THIS ONE WILL TURN NORTH TEXAS QUITE COLD AS PARTIAL THICKNESSES FALL INTO THE 1270-1290 RANGE...BUT RIGHT NOW DO NOT SEE ANY WINTER PRECIPITATION BEHIND THIS FRONT. FOR THE REST OF THE FORECAST... WE/VE HEDGED TOWARD THE ECMWF MODEL WHICH BRINGS ANOTHER ARCTIC FRONT INTO NORTH TEXAS ON SUNDAY. THIS ONE MAY BE EVEN COLDER THAN FRIDAY...SO HAVE UNDERCUT MIN/MAX TEMPS THROUGH MONDAY AS ECMWF PARTIAL THICKNESSES ARE LOWER THAN THE GFS VALUES OF FRIDAY NIGHT. THERE REMAINS A BIT OF UNCERTAINTY IN THE FRIDAY THROUGH MONDAY TIME PERIOD DUE TO THE DEVELOPMENT OF ANOTHER CLOSE LOW OFF THE CALIFORNIA COAST THIS WEEKEND AND THE AMOUNT OF RIDGING THAT FORMS OVER NORTHERN MEXICO AND THE DESERT SOUTHWEST EARLY NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 52 33 47 32 41 / 0 10 10 10 30 WACO, TX 52 34 50 32 43 / 0 20 10 10 20 PARIS, TX 49 31 43 25 39 / 0 10 10 10 30 DENTON, TX 52 31 47 27 41 / 0 10 10 10 30 MCKINNEY, TX 51 32 45 26 38 / 0 10 10 10 30 DALLAS, TX 52 34 48 32 42 / 0 10 10 10 30 TERRELL, TX 51 33 47 30 39 / 0 10 10 10 30 CORSICANA, TX 52 35 48 31 41 / 0 10 10 10 30 TEMPLE, TX 53 36 48 34 44 / 0 20 20 20 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 42/75 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 528 PM CST MON JAN 29 2007 .AVIATION ... MODELS GIVING MIXED SIGNALS ON MOISTURE IN THE METRO DFW TRACON AREA. STRATUS DECK OVR SOUTH CENTRAL TX IS STILL MOVG TOWARD NE TEXAS. MAV AND RUC IN FAIRLY CLOSE AGREEMENT WITH CEILINGS AROUND 040-050 THRU 06Z. CDFNT MOVG ACRS SW OK MOVING AROUND 10 KTS. TIMING LOOKS GOOD ARND 06/07Z. LAMP IS FAR TOO AGGRESSIVE IN TIMING OF FRONTAL PASSAGE SO HAVE SLOWED TIMING TO THE 06-07Z TIMEFRAME. 50 && ...WINTRY MIX POSSIBLE FOR THE WESTERN AND NORTHERN AREAS WEDNESDAY THROUGH THURSDAY... .DISCUSSION... COMPLICATED FORECAST FOR THE NEXT SEVERAL DAYS...BUT WE DO NOT ANTICIPATE A MAJOR WINTER EVENT. JUST A WINTRY MIX AT TIMES WITH LITTLE OR NO ICE ACCUMULATION. UPPER LOW OFF THE CALIFORNIA COAST WILL DRIFT INLAND BY TUESDAY NIGHT...WEAKEN INTO AN OPEN WAVE THEN MERGE WITH STRONG SHORT WAVE COMING OUT OF CANADA AND TRANSLATE ACROSS THE SOUTHERN PLAINS WEDNESDAY NIGHT. SEVERAL MORE UPSTREAM SHORT WAVES WILL MOVE INTO THE MEAN TROUGH ON THURSDAY AND THIS WEEKEND...STRENGTHENING THE LONG WAVE TROUGH ACROSS NOAM AND AIDING THE SURGE OF ARCTIC AIR SOUTHWARD. WE CONTINUE TO FEEL THAN MODELS DO NOT HAVE A GOOD HANDLE ON THE ARCTIC SURGES...THUS MOS TEMPS SEEM TOO WARM...ESPECIALLY FOR THIS WEEKEND AND EARLY NEXT WEEK. THERE WILL BE A CHANCE OF RAIN OVER THE SOUTHERN CWA TONIGHT AS A SURFACE WAVE FORMS ALONG THE TEXAS COAST AND MOVES EAST AHEAD OF THE FIRST COLD FRONT ARRIVING OVERNIGHT. COLD AIR SETTLES OVER NORTH TEXAS WEDNESDAY AS AN IMPULSE FROM THE WEST NEARS AND INCREASES PRECIPITATION CHANCES DURING THE DAY AND INTO THURSDAY. THERE WILL BE SOME DRY AIR ALOFT OVER THE WEST THAT MIGRATES NORTH WITH TIME DUE TO WARM AIR ADVECTION...THUS WET BULBING EFFECTS SHOULD PRODUCE SOME SLEET OVER THE WEST AND NORTH COUNTIES WEDNESDAY AND WEDNESDAY NIGHT. ALSO...LIQUID RAIN COULD FALL INTO SUB-FREEZING AIR IN THE EARLY MORNING HOURS...THUS HAVE ADDED SOME FREEZING RAIN. THE PRECIPITATION PROCESS WILL DIMINISH AS SHORT WAVE ENERGY MOVES EAST LATE THURSDAY NIGHT. ANOTHER ARCTIC COLD FRONT ARRIVES FRIDAY. THIS ONE WILL TURN NORTH TEXAS QUITE COLD AS PARTIAL THICKNESSES FALL INTO THE 1270-1290 RANGE...BUT RIGHT NOW DO NOT SEE ANY WINTER PRECIPITATION BEHIND THIS FRONT. FOR THE REST OF THE FORECAST... WE/VE HEDGED TOWARD THE ECMWF MODEL WHICH BRINGS ANOTHER ARCTIC FRONT INTO NORTH TEXAS ON SUNDAY. THIS ONE MAY BE EVEN COLDER THAN FRIDAY...SO HAVE UNDERCUT MIN/MAX TEMPS THROUGH MONDAY AS ECMWF PARTIAL THICKNESSES ARE LOWER THAN THE GFS VALUES OF FRIDAY NIGHT. THERE REMAINS A BIT OF UNCERTAINTY IN THE FRIDAY THROUGH MONDAY TIME PERIOD DUE TO THE DEVELOPMENT OF ANOTHER CLOSE LOW OFF THE CALIFORNIA COAST THIS WEEKEND AND THE AMOUNT OF RIDGING THAT FORMS OVER NORTHERN MEXICO AND THE DESERT SOUTHWEST EARLY NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 52 33 47 32 41 / 0 10 10 10 30 WACO, TX 52 34 50 32 43 / 0 20 10 10 20 PARIS, TX 49 31 43 25 39 / 0 10 10 10 30 DENTON, TX 52 31 47 27 41 / 0 10 10 10 30 MCKINNEY, TX 51 32 45 26 38 / 0 10 10 10 30 DALLAS, TX 52 34 48 32 42 / 0 10 10 10 30 TERRELL, TX 51 33 47 30 39 / 0 10 10 10 30 CORSICANA, TX 52 35 48 31 41 / 0 10 10 10 30 TEMPLE, TX 53 36 48 34 44 / 0 20 20 20 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 42/75 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 824 PM CST MON JAN 29 2007 .UPDATE... LATEST THINKING HERE IS TO LET ADVISORY GO AS SCHEDULED AT 9 PM. ONLY FLY IN OINTMENT IS WISCONSIN RIVER VALLEY AREA WHERE MOD/HEAVY SNOW STILL FALLING /KLNR AT 1/4SM IN +SN RIGHT NOW/ AND WINDS AT KPDC JUST GUSTED TO 27KTS...SO NO DOUBT THIS AREA STILL RECEIVING IMPACTIVE WEATHER FOR TRAVEL. MAY NEED LOCAL EXTENSION TO 11 PM IN FAR SRN CWA TO GET PAST THE BURST OF WINDS. SFC LOW PULLING QUICKLY EAST THROUGH SRN WISC. VERY COMPACT LITTLE WAVE EMBEDDED DEEPER IN THE LARGE TROUGH DROPPING THROUGH THE UPPER MIDWEST. SMALL SCALE ISALLOBARIC COUPLET NOW ACROSS WRN CWA...WITH STRONGEST PUSH OF WIND /30KT/ ON THE LEADING EDGE WHICH IS CROSSING MS RIVER SOUTH OF LA CROSSE AT THIS MOMENT. WINDS AND VISIBILITIES HAVE IMPROVED ACROSS SERN MN/WRN PORTIONS OF NERN IA SINCE ABOUT 7 PM WHEN I MADE THE LAST ROUND OF CALLS TO LAW ENFORCEMENT. THINK TRENDS OF IMPROVEMENT IN THESE AREAS WILL CONTINUE...SO FEEL PRETTY CONFIDENT ABOUT DROPPING ADVRY WEST OF ALLAMAKEE/CLAYTON COUNTIES AT 9PM. LOCAL EXTENSION MAY BE NEEDED TO THE EAST AS MENTIONED ABOVE. THE MESOSCALE BAND OF SNOW ON NRN/NERN FRINGE OF THE TIGHT CIRCULATION WAS INTENSE...WITH WHAT APPEARS TO BE A 2-2.5+ INCH BAND ACROSS SRN HOUSTON/VERNON/CRAWFORD/FILLMORE/RICHLAND COUNTIES. WOULD NOT BE SURPRISED TO SEE A 3 INCH REPORT COME OUT OF THIS BAND YET. PLENTY OF COLD AIR/WIND CHILLS TO FILTER INTO CWA OVERNIGHT. LATEST RUC INDICATING BLOB OF DEEPER MOISTURE TO ROTATE SOUTHWEST OFF LAKE SUPERIOR INTO CWA AFTER MIDNIGHT AS LOW/MID LEVEL FLOW VEERS AROUND TO THE NORTH/NORTHEAST. CURRENT GRIDS HANDLE THIS. WILL MAKE FINAL CALL ON ADVRY AND HAVE FRESH ZONES OUT BY 9 PM. THANKS TO MEDIA PARTNERS AND LAW ENFORCEMENT AND SURROUNDING NWS WFO/S THIS EVENING FOR REPORTS AND COLLABORATION. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...SNOW AND BLOWING SNOW ADVISORY UNTIL 9 PM CST THIS EVENING FOR WIZ054-WIZ061. MN...SNOW AND BLOWING SNOW ADVISORY UNTIL 9 PM CST THIS EVENING FOR MNZ086-MNZ087-MNZ094-MNZ095. IA...SNOW AND BLOWING SNOW ADVISORY UNTIL 9 PM CST THIS EVENING FOR IAZ008-IAZ009-IAZ010-IAZ011-IAZ018-IAZ019-IAZ029-IAZ030. && $$ BINAU wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 230 PM CST MON JAN 29 2007 .DISCUSSION...SHORT TERM FOCUS ON THREAT OF SNOW TONIGHT AND AGAIN LATER WEDNESDAY INTO WEDNESDAY NIGHT. COMPACT SHORT WAVE VICINITY OF ALBERT LEA MN /KAEL/ TRACKING SOUTHEAST. LOW LEVEL CONVERGENCE AIDING FORCING PRODUCING NUMEROUS AREAS OF VISIBILITIES LESS THAN ONE MILW ACROSS SOUTHEAST MINNESOTA. ECHOES EXPANDING RAPIDLY ACROSS JUST WEST OF STATE LINE WITH DECORAH NOW DOWN TO 3/4 MILE. LATEST WS-ETA AND RUC SHOWS STRONG FORCING WITH 700MB OMEGA EXCEEDING 10 MICROBARS PASSING ACROSS SOUTHWEST PART OF COUNTY WARNING AREA THROUGH 03Z. UPSTREAM SNOWFALL OF 1 TO 2 INCHES REPORTED IN SOUTHERN MINNESOTA WITH THIS FEATURE. BELIEVE HEAVIEST AMOUNTS WILL AFFECT GREEN...LAFAYETTE...IOWA...ROCK AND PERHAPS SOUTHERN WALWORTH...DANE COUNTIES INTO THE EARLY EVENING. STRONG FORCING REMAINS OVER SOUTH SO WILL DROP OFF POPS TO CHC OR AREAS IN NORTH. REMNANTS OF DEFORMATION ZONE TO THE NORTH PASSES THROUGH LATER TONIGHT INTO TUESDAY MORNING SO WL TRAIL DOWN POPS TO CHC AFT MID AND FLURRIES TUE. CONCERN OVER BURST OF SNOW DURING RUSH HOUR IN THE SOUTHWEST. WL STRESS IN NOWS AND HWO...BUT PONDERING QUICK HITTING SNOW ADVY IN MY SOUTHWEST. BOTH GFS AND NAM SLOWER WITH SHORT WAVE TROUGH ON WEDNESDAY BUT WEAK Q-VECTOR CONVERGENCE AND ISENTROPIC UPGLIDE STILL SPREAD INTO SOUTHERN WISCONSIN DURING THE AFTERNOON. WL CONTINUE SMALL POPS FOR NOW BUT IF TREND CONTINUES...LATER SHIFTS MAY NEED TO TONE DOWN TO FLURRIES OR FOCUS MAINLY ON WEDNESDAY NIGHT. SHORT RANGE ENSEMBLE SHOWING PROBABILITIES FOR MEASUREABLE PRECIPITATION INCREASING TO OVER 50 PERCENT WEDNESDAY NIGHT...BUT FOR NOW WL HOLD ON TO 30 TO 40 PERCENT RANGE A BIT MORE CONFIDENCE IN DAYS 4-7 PERIOD AS GFS SHOWING CONSISTENCY OVER LAST SEVERAL RUNS AND GENERAL AGREEMENT WITH ECMWF AND CANADIAN AS WELL AS REASONABLE AGREEMENT IN ENSEMBLE MEMBERS DURING THE PERIOD. FOCUS OF LONG TERM PERIOD OF MUCH ANTICIPATED SURGE OF ARCTIC AIR AS POLAR VORTEX AND LONG WAVE TROF DEEPENS ACROSS CANADA INTO EASTERN CONUS. HOWEVER GFS HAS BEEN SLOWING UP BITTER COLD 85H TEMPERATURES OF LOWER THAN -25C UNTIL LATE IN THE WEEKEND. 85H TEMPERATURE NORMALIZED ANOMOLY OF 2 TO 3 UNITS VALID 00Z/05 SO TEMPERATURES THIS COLD BECOMING A BIT MORE SIGNIFICANT FOR EARLY FEBRUARY. /RECORD LOWEST WI AND MN TEMP SET IN EARLY FEBRUARY 11 YEARS AGO ON GROUNDHOG DAY/. NOT MUCH CHANGE IN 500H 5 DAY MEANS AS COLDEST PERIOD WITH LOWEST HEIGHT ANOMOLY OF 200 TO 300 METERS OVER WESTERN GREAT LAKES CENTERED ON 00Z/05 WITH SOME SLIGHT ABATEMENT OF NEGATIVE ANOMOLY BY THE END OF FIRST WEEK OF FEBRUARY. MOISTURE STILL LACKING AS SIGNIFICANT COLD FRONT MOVES THROUGH LATE THURSDAY NIGHT/FRIDAY TIME FRAME. MEDIUM RANGE ENSEMBLE PERCENT OF MEASUREABLE PROGNOSIS REMAINS VERY LOW AS DOES TOTAL COLUMN MOISTURE HOWEVER CONSIDERING STRENGTH OF SHORT WAVE...WL UP POPS SLIGHTLY TO CHC CATEGORY IN WEST LATE THURSDAY NIGHT AND EAST FRIDAY MORNING. && .MKX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ MBK wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 500 AM EST WED JAN 31 2007 .SYNOPSIS... 07Z WATER VAPOR AND RUC ANALYSIS SHOWING A FAIRLY ACTIVE PATTERN ACROSS THE CONUS. SEVERAL VERY DISTINCT SHORTWAVES CAN BE SEEN RIDING THE NORTHERN STREAM...ONE DROPPING OUT OF SOUTH-CENTRAL CANADA INTO THE NORTHERN PLAINS AND ANOTHER ABOUT TO EXIT THE CAROLINA COAST. WEAKLY AMPLIFIED RIDING IS SEEN ACROSS THE LOWER MISSISSIPPI VALLEY FOLLOWED CLOSELY BY ENERGY PUSHING ACROSS THE SOUTHWEST UNITED STATES. AT THE SURFACE WE SEE HIGH PRESSURE BUILDING TO OUR NORTH ACROSS THE TENNESSEE VALLEY. A COLD FRONT ALONG THE LEADING EDGE OF THIS HIGH IS NOW PUSHING THROUGH THE FORECAST AREA BRINGING ANOTHER SHOT OF COOL AND DRY AIR FOR TODAY. LATEST SATELLITE IMAGERY SHOWS THE BACK EDGE OF THE CLOUDS CONTINUING TO PROGRESS EAST AND SOUTHEAST ACROSS THE AREA. MOST LOCATIONS SHOULD SEE A PARTLY TO MOSTLY SUNNY MORNING WITH THE EXCEPTION THE THE SOUTHEAST BIG BEND WHICH WILL TAKE A BIT LONGER TO CLEAR OUT. NEARLY STATIONARY WEAK LOW PRESSURE CAN ALSO BE SEEN IN THE WESTERN GULF. THIS LOW WILL WEAKEN TODAY AND THEN BE REPLACED BY A MUCH MORE DYNAMIC SYSTEM THAT SHOULD BE OUR NEXT WEATHER MAKER STARTING LATE TONIGHT AND THROUGH THE DAY ON THURSDAY. && .SHORT TERM... (TODAY-FRIDAY) AS MENTIONED ABOVE COLD FRONT WILL CLEAR SOUTH OF THE FORECAST AREA DURING THE MORNING HOURS TODAY. THE CLOUDS WILL CONTINUE TO PUSH SOUTH AS WELL WITH PARTLY TO MOSTLY SUNNY SKIES FOR MOST LOCATIONS THIS MORNING. LOW PRESSURE WILL BEGIN TO TAKE SHAPE IN THE WESTERN GULF THIS AFTERNOON WITH A DEVELOPING WARM FRONT MOVING TOWARD THE NORTH-CENTRAL GULF COAST BY LATE IN THE DAY. WOULD EXPECT TO SEE HIGH CLOUDS ASSOCIATED WITH THIS FEATURE BEGIN TO OVERSPREAD OUR SKIES BY LATER TODAY AND ESPECIALLY DURING THE EVENING HOURS. WITH COLD AIR ADVECTION THROUGH THE DAY...HIGH TEMPERATURES WILL BE ON THE COOL SIDE ONLY REACHING INTO THE MIDDLE 50 MOST LOCATIONS. RAIN CHANCES WILL BEGIN TO INCREASE FROM WEST TO EAST TONIGHT AS THE WARM FRONT ASSOCIATED WITH THE DEVELOPING STORM IN THE WESTERN GULF BEGINS TO APPROACH. NOT THINKING THAT THE RAIN TONIGHT WILL BE ALL THAT HEAVY...BUT COVERAGE COULD BECOME QUITE WIDESPREAD AFTER MIDNIGHT IN THE WESTERN HALF OF THE CWA. LOW BEINGS TO INTENSIFY AND MOVE NORTHEAST ON THURSDAY. GUIDANCE IS IN FAIRLY GOOD AGREEMENT ON A LOW POSITION SOMEWHERE NEAR OR JUST NORTH OF MOBILE ALABAMA BY THURSDAY EVENING. THE WARMFRONT SHOULD SLOWLY PUSH NORTH THROUGH THE DAY...ALTHOUGH WIDESPREAD AREAS OF SHOWER AND ISOLATED THUNDERSTORMS WILL HELP TO SLOW THE FRONTS PROGRESS. RAINFALL ON THURSDAY MAY BE MODERATE TO HEAVY AT TIMES...ESPECIALLY FROM THE AFTERNOON INTO THE OVERNIGHT HOURS. TEMPERATURES WILL BE QUITE TRICKY. MOST SO ACROSS THE NORTH. RIGHT NOW WILL BE GOING WITH HIGHS FROM NEAR 60 NORTH TO THE MIDDLE/UPPER 60 SOUTH. TEMPERATURES ACROSS THE NORTH ARE LIKELY TO BE RATHER COOL THROUGH A GOOD PORTION OF THE DAY UNTIL THE WARM FRONT CAN PUSH THROUGH. FOR THAT REASON THE HIGH NEAR 60 ACROSS OUR NORTHERN AL/GA COUNTIES WILL LIKELY WAIT TO VERY LATE IN THE DAY. ALSO AS THE DAY PROGRESSES...JUST ENOUGH INSTABILITY IS POSSIBLE FOR ISOLATED TO SCATTERED THUNDERSTORMS IN THE WARM SECTOR BEHIND THE WARM FRONT. SHEAR PROFILES LOOK IMPRESSIVE ENOUGH TO PRODUCE A FEW STRONG THUNDERSTORMS AND SPC HAS OUTLOOKED PORTIONS OF OUR AREA FOR A SLIGHT RISK OF SEVERE WEATHER. THE LOW WILL PUSH OFF THE SOUTHEAST COAST LATE THURSDAY NIGHT DRAGGING AN ASSOCIATED COLD FRONT THROUGH AREA. SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE THROUGH MUCH OF THE NIGHT UNTIL THIS FRONT HAS PASSES...ESPECIALLY IN THE EAST. ONCE AGAIN SOME OF THE RAINFALL MAY BE ON THE HEAVY SIDE AT TIMES. EXACT AMOUNTS ARE UNCERTAIN BUT A GOOD PORTION OF THE FORECAST AREA IS LIKELY TO SEE 1"+ RAINFALL WITH THIS SYSTEM WITH THE POTENTIAL FOR MORE. WILL OUTLOOK AS WELL IN THE HWO. COLD FRONT WILL BE SLOW TO CLEAR THE SOUTHEAST BIG BEND WITH A FEW LINGERING SHOWERS LIKELY INTO FRIDAY MORNING. GUIDANCE SPLITS AT THIS POINT...WITH THE GFS CLEARING US OUT AND THE NAM HOLDING THE FRONT AND SHOWER ACTIVITY ACROSS OUR SOUTHERN ZONES. NAM IS AN OUTLIER IN ITS SOLUTION WITH THE GFS HAVING STRONG BACKING FROM THE ECMWF. FOR THIS REASON DROPPED POPS BY LATE FRIDAY THROUGH FRIDAY NIGHT FOR MOST LOCATIONS. .LONG TERM... (SATURDAY-WEDNESDAY) AREA IS IN THE SQUEEZE ON SATURDAY AND SATURDAY NIGHT BETWEEN HIGH PRESSURE TO OUR NORTH AND THE FRONT TO SOUTH SOUTH TRYING TO COME BACK NORTH. GFS HAS BEEN VERY PERSISTENT ON BRINGING QPF BACK INTO THE SOUTHEAST HALF OF THE AREA BY LATE SATURDAY AND THROUGH SATURDAY NIGHT. RAN THE FORECAST IN A SIMILAR FASHION WITH SLIGHT CHANCE POPS NORTHWEST TO LIKELY POPS IN THE FAR SOUTHEAST. EITHER WAY...HIGH PRESSURE TO THE NORTH LOOKS TO WIN THE BATTLE BY SUNDAY WITH THE PRECIP PUSHING SOUTH AND EAST OF THE AREA BY EARLY AFTERNOON. JUST FOR MENTIONING...THE AIRMASS COMING INTO THE REGION SATURDAY NIGHT INTO SUNDAY IS RATHER COLD. IF...IF THERE WAS ANY LINGERING LIGHT SHOWER ACTIVITY ACROSS SOUTHEAST ALABAMA OR SOUTHWEST GEORGIA...THICKNESS VALUES BOTH (1000-850/850-700) WOULD INDICATED THE POTENTIAL FOR A FEW FLAKES OF SNOW TO MIX IN. AT THIS TIME THE THINKING IS THAT THE PRECIP WILL EXIT TO RAPIDLY...BUT THERE IS A CHANCE. EITHER WAY ANY LINGERING PRECIP WOULD BE VERY LIGHT AND ANY FROZEN PRECIP WOULD NOT AMOUNT TO MUCH. UPPER PATTERN FOR THE FIRST PART OF NEXT WEEK WILL FEATURE A VERY DEEP AND COLD UPPER LEVEL TROUGH IN THE EASTERN CONUS AND SURFACE HIGH PRESSURE TO OUR NORTH. AT THIS TIME IT LOOKS DRY BUT COOL FOR THE MONDAY-WEDNESDAY TIMEFRAME. && .AVIATION... DESPITE WIDESPREAD OVERCAST CONDITIONS AND OCCASIONAL SPRINKLES SO FAR TONIGHT...VFR WEATHER IS BEING REPORTED AT ALL OF OUR LOCAL STATIONS. THE CEILINGS (AROUND 8K FT) WILL GRADUALLY DISSIPATE FROM NORTHWEST TO SOUTHEAST BETWEEN NOW AND DAY BREAK...AS WILL THE VERY LIGHT SHOWERS. IN FACT...ANY SHOWERS THAT OCCUR TONIGHT WILL BE OF LITTLE IMPACT TO OPERATIONS. WINDS WILL GENERALLY BE 10 KT OR LESS TONIGHT AND WEDNESDAY...AND QUICKLY VEER FROM NORTHWEST EARLY TODAY...TO EAST BY WEDNESDAY EVENING. A MORE SIGNIFICANT WEATHER SYSTEM WILL DEVELOP IN THE GULF AND APPROACH LATER TODAY AND TONIGHT...BUT IT IS STILL A BIT TOO EARLY TO FORECAST ANY RAIN THROUGH 06 UTC. && .MARINE... HIGH PRESSURE BRIEFLY BUILDS ACROSS THE COASTAL WATERS TODAY BEFORE RAPIDLY MOVING OFF THE SOUTHEAST COAST AS LOW PRESSURE DEVELOPS IN THE WESTERN GULF. THE TIGHTENING GRADIENT BETWEEN THIS HIGH AND THE DEVELOPING LOW WILL INCREASE WINDS AND SEAS TO CAUTION LEVELS IN THE OFFSHORE LEGS TODAY AND FOR ALL LEGS TONIGHT. THIS LOW WILL INTENSIFY AS IT MOVES NORTH OF THE COASTAL WATERS THURSDAY AND THURSDAY NIGHT. WIND AND SEAS ARE ANTICIPATED TO REACH ADVISORY LEVELS THURSDAY INTO THURSDAY NIGHT WITH WIDESPREAD SHOWERS AND THUNDERSTORMS. SOME OF THE STORMS WILL HAVE THE POTENTIAL TO BECOME STRONG TO SEVERE. COLD FRONT WILL CROSS THE WATERS THURSDAY NIGHT AND EARLY FRIDAY WITH HIGH PRESSURE BRIEFLY BUILDING IN BY LATE IN THE DAY. GRADIENT WILL TIGHTEN ONCE AGAIN FOR THE UPCOMING WEEKEND BETWEEN THE FRONT TO OUR SOUTH AND STRONG HIGH PRESSURE BUILDING TO OUR NORTH. EXPECT AN EXTENDED PERIOD OF CAUTION LEVEL WINDS FROM THE NORTH AND NORTHEAST BOTH SATURDAY AND SUNDAY. && .FIRE WEATHER... CANCELLED THE RED FLAG WARNING FOR OUR GEORGIA COUNTIES FOR THIS AFTERNOON...DEWPOINTS HAVE BEEN PERSISTENTLY TOO LOW IN THE GUIDANCE AND ADJUSTED CURRENT GRIDS TO REFLECT THIS. RH VALUES ARE NO LONGER ANTICIPTATED TO REACH CRITICAL DURATIONS. RED FLAG WARNING REMAIN IN EFFECT FOR PORTIONS OF THE EASTERN FLORIDA PANHANDLE AND BIG BEND REGIONS. INCREASING MOISTUREA AND RAIN CHANCES FOR THURSDAY WILL END ANY FIRE WX THREAT. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 54 43 67 56 66 / 10 60 90 90 30 PANAMA CITY 54 49 67 56 65 / 10 70 90 90 20 DOTHAN 51 43 62 49 63 / 10 70 90 80 20 ALBANY 51 41 62 49 64 / 0 50 90 90 20 VALDOSTA 54 42 68 57 66 / 10 40 80 90 30 CROSS CITY 57 46 69 61 69 / 10 40 70 80 50 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...RED FLAG WARNING FROM NOON EST /11AM CST/ TODAY TO 5 PM EST /4 PM CST/ THIS AFTERNOON FOR THE FOLLOWING ZONES: CALHOUN...DIXIE ...GADSDEN...HOLMES...INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE ...LEON...LIBERTY...MADISON...TAYLOR...WAKULLA...AND WASHINGTON. GMZ750...NONE. GMZ755...NONE. GMZ770...NONE. GMZ775...NONE. && $$ AVIATION...FOURNIER REST OF DISCUSSION...MROCZKA fl AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE STATE COLLEGE PA 107 AM EST WED JAN 31 2007 .AVIATION /06Z-06Z/... IR SAT IMAGERY SHOWING SOME CONSIDERABLE BINOVC SC DECK...WITH SOME SITES SCOURING OUT TO SKC-SCT. UPSLOPE/LAKE SNOW SHOWERS WILL KEEP IFR/MVFR CONDS ACROSS THE WESTERN TAFS /KBFD- KJST/ WITH DOWNSLOPING WRLY COMPNT TO THE LLVL WND FIELD AIDING IN VFR CONDS ELSEWHERE. HOWEVER...STILL CANNOT RULE OF A BRIEF REDUCTION TO MVFR AT KUNV/KIPT/KAOO THRU THE EARLY MORNING HOURS WITH OCNL -SHSN. WEST TO WNW SFC WNDS 10-15KTS WITH HIGHER GUSTS...ESP AT KJST AND KMDT. HI PRES CURRENTLY OVR THE MID MS VLY WILL MOVE EWD INTO THE SRN MID ATLANTIC STATES...EFFECTIVELY LOWERING INVERSION HGTS AND SHUTTING DOWN THE LAKE SNOWS - ALLOWING KBFD/KJST TO IMPROVE BY LATE MORNING OR EARLY AFT. && .PREV DISCUSSION... /ISSUED 1223 AM EST WED JAN 31 2007/ SHORT TERM /REST OF TONIGHT/... JUST A QUICK UPDATE TO DROP THE ADVISORY FOR THE NRN MTS/POCONOS. ONLY A FEW FLURRIES WILL BE LEFT THERE...AS LOW IS WELL TO THE EAST AND INVERSION LOWERING SFC PRESSURES RISING. WILL TWEAK JUST THE FIRST PD WORDING FOR NOW. ALSO RE-ISSUED THE WSW FOR NOW...WITH LIGHT SNOW CONTINUING AS THE UPSLOPE AND CROSS-LAKE FETCH CONTINUES. SO WILL JUST CONTINUE THEM FOR NOW. PREV DISCUSSION... /ISSUED 1012 PM EST TUE JAN 30 2007/ SHORT TERM /THROUGH TUESDAY NIGHT/... WILL SEND OUT A QUICK...LATE EVENING ZONE UPDATE TO FRESHEN UP THE WORDING FOR SNOW SHOWERS ACROSS THE REGION. ARCTIC FRONT HAS PUSHED EAST OF THE SUSI VALLEY...TAKING THE HEAVY SQUALLS WITH IT. WEAKENING MID LEVEL DEFORMATION SNOWS ACROSS THE NCENT MTNS WILL BRING ANOTHER INCH OR TWO TO SOME LOCATIONS OVER THE NEXT FEW HOURS WITHIN THE SNOW ADVISORY...WHICH SET TO EXPIRE AT MIDNIGHT EST. PERSISTENT LAKE EFFECT/OROGRAPHIC SNOWS ACROSS THE NW MTNS AND LAUREL HIGHLANDS RESPECTIVELY WILL CONTINUE TO ACCUMULATE A FEW MORE INCHES OVERNIGHT...SO NO CHANGES TO THE LAKE EFFECT/SNOW ADVISORIES FOR THOSE AREAS. ELSEWHERE...EXPECT FLURRIES AND A BRIEF HEAVIER SNOW SHOWER OVERNIGHT AS THE PRIMARY 700-500 HPA THERMAL TROUGH MOVES SE FROM THE GLAKES. ACCUMULATIONS WILL BE LESS THAN AN INCH ACROSS THE CENTRAL RIDGE AND VALLEY REGION. OVC LAYER WILL BREAK UP AFTER MIDNIGHT ACROSS THE LOWER SUSQ VALLEY AS DRIER DEWPOINTS IN THE UPPER SINGLE DIGITS ADVECT EAST VIA A DOWNSLOPE LLVL FLOW. TRIMMED HOURLY AND MIN TEMPS OVERNIGHT BY 2-4 DEG F IN MANY LOCATIONS. PREV DISCUSSION... /ISSUED 728 PM EST TUE JAN 30 2007/ SHORT TERM /THROUGH TONIGHT/... AREA OF INSTABILITY WITH TOTAL TOTALS NEAR 50 CROSSING THE SUSQ VALLEY...ALONG WITH A RATHER STRONG...ALBEIT COMPACT UPPER SHORT WAVE MOVE EAST OVER THE NCENT MTNS WILL BRING NUMEROUS SNOW SHOWERS AND LOCALLY HEAVY SNOW SQUALLS EARLY TONIGHT. ISSUED A SNOW ADVISORY ACROSS THE NCENT MTNS THROUGH MIDNIGHT WHERE A MESO-B MID LVL DEFORMATION ZONE AND CORRESPONDING EAST/WEST BELT OF ENHANCED 850-700 HPA OMEGA WILL LEAD TO SEVERAL INCHES OF NEW SNOW. SNOW SHOWERS AND SQUALLS WILL DIMINISH TO SCATTERED FLURRIES ACROSS THE CENTRAL VALLEYS AND SUSQ RIVER VALLEY LATE THIS EVENING. PREV DISCUSSION... /ISSUED 325 PM EST TUE JAN 30 2007/ SHORT TERM /TONIGHT THROUGH WEDNESDAY/... MESO ANAL SHOWS SFC LOW JUST WEST OF BFD AT 18Z...WITH THE COLD FRONT MOVING THRU SWRN PA. RUC SHOWS A POCKET OF RELATIVELY UNSTABLE AIR...LOW-MID LEVEL LAPSE RATES IN EXCESS OF 6C/KM AND T-TOTALS TOPPING 50...HELPING TRIGGER THE CURRENT SNOW SHOWERS AND SQUALLS MOVING ACROSS THE AREA. THE BEST FORCING/INSTABILITY STARTS TO WANE AFTER ABOUT 21Z ACCORDING TO SHORT TERM GUIDANCE...WITH THE FRONT EXPECTED TO CLEAR MY EASTERN ZONES BY 00Z. AFTER THE FROPA...WE WILL TRANSITION INTO A MORE TYPICAL NW FLOW REGIME WITH LAKE EFFECT AND OROGRAPHICALLY FORCED SNOWS IN THE WEST...AND ACTIVITY TAPERING OFF TO JUST SCATTERED SNOW SHOWERS AND FLURRIES THE FURTHER DOWNWIND OF THE LAKES AND LAURELS ONE GETS. ONLY CONCERN IS A HINT IN THE MODELS THAT THE UPPER-AIR PORTION OF THE OCCLUDED FRONT HANGS TOUGH FOR A TIME INTO NW PA...ENHANCING THE CONVERGENCE THERE INTO THE EVENING. THIS SHOWS UP AS A WELL DEFINED THERMAL RIDGE UP THRU ABOUT 850MB IN ALL THE SHORT RANGE GUIDANCE. THEY SHIFT THIS EAST OF THE AREA AFTER 03Z. WEDNESDAY WILL SEE CONDITIONS IMPROVING AS INVERSION HEIGHTS LOWER THROUGHOUT THE DAY. THE BEST CHANCE OF LINGERING SNOW WILL BE OVER WESTERN HIGH TERRAIN. ELSEWHERE WE SHUD SEE LITTLE MORE THAN FLURRIES. LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... UPPER TROFFING OVER EASTERN NORTH AMERICA LOOKS TO DOMINATE THE LONG TERM PERIOD. THIS WILL LEAD TO NEAR TO BELOW NORMAL TEMPERATURES EARLY IN THE PERIOD AND POSSIBLY SIGNIFICANTLY BELOW NORMAL TEMPERATURES LATE IN THE PERIOD. MOST OF THE PERIOD LOOKS DRY...BUT TWO OPPORTUNITIES FOR PCPN STAND OUT. A WEATHER SYSTEM THAT HAS BEEN ADVERTISED FOR SEVERAL DAYS TO AFFECT THE REGION LATE THURSDAY INTO FRIDAY CONTINUES TO LOOK COMPLEX...WITH VARYING RUN TO RUN MODEL SOLUTIONS. A SOUTHERN STREAM TROF IS FORECAST TO INDUCE CYCLOGENESIS OVER THE SOUTHEAST U.S. THURSDAY NIGHT WITH A NORTHERN STREAM TROF FORECAST TO SWING THROUGH THE REGION LATER FRIDAY. MUCH YET DEPENDS ON THE TRACK OF THE COASTAL LOW AND ANY PHASING THAT MAY TAKE PLACE BETWEEN THE TWO STREAMS. AT THIS TIME...THERE IS A HIGH PROBABILITY OF MEASURABLE ACROSS ALL OF THE CWA...WITH POTENTIAL FOR A SEVERAL INCH SNOWFALL ACROSS THE REGION...EVEN THE LOWER SUSQUEHANNA VALLEY...WHERE SNOWFALL SO FAR THIS SEASON IS LESS THAN AN INCH TOTAL. A PRONOUNCED ARCTIC TROF IS FORECAST TO MOVE THROUGH THE FORECAST AREA ON MONDAY...POTENTIALLY BRINGING IN THE COLDEST AIR YET THIS WINTER. AVIATION /20Z-18Z/... THE AFTERNOON`S WIDESPREAD IFR CAUSED BY THE SHORTWAVE AND SNOW SHOWERS SHUD BEGIN TO IMPROVE IN MOST AREAS THIS EVENING AS THE UPPER TROF MOVES EAST OF THE REGION AND A WEST-NORTHWEST FLOW DEVELOPS. LIKE A BROKEN RECORD THOUGH...JST/BFD WILL NOT SHARE IN THE IMPROVEMENT AS UPSLOPE AND PROXIMITY TO LAKE ERIE CONSPIRE TO KEEP BOTH TERMINALS MAINLY DOWN BELOW 3000/3 WITH FREQUENT SNOW SHOWERS BRINGING EVEN LOWER CONDITIONS. WILL PROB SEE AOO/UNV/IPT IMPROVE TO MVFR CEILINGS AND MOSTLY UNLIMITED VIS WITH ONLY OCNL SNOW SHOWERS BRINGING BRIEFLY REDUCED VIS AFTER 00Z...WITH VFR DEVELOPING SLOWLY LATER TONIGHT INTO EARLY WED MORNING. STILL A QUESTION AS TO WHETHER THE FAR SERN TERMINALS WILL SEE MUCH INCLEMENT WX AT ALL AS THE SYSTEM IS ALREADY MOISTURE STARVED AND DOWN-SLOPING FLOW WILL ONLY HELP IN MAKING MUCH OF THE SNOW SHOWER ACTIVITY DRY UP BEFORE IT MAKES IT INTO THE LOWER SUSQ VALLEY. THINK THERE IS A CHC OF SNOW SHOWERS AND BRIEFLY LOWER CONDITIONS THRU THE EVENING...BUT AFTER THAT CIG/VIS SHUD NOT POSE MUCH OF A CHALLENGE THERE. && .CTP WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR PAZ004-005-010. SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR PAZ024-033. && $$ AVIATION...STEINBUGL pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1223 AM EST WED JAN 31 2007 .SHORT TERM /REST OF TONIGHT/... JUST A QUICK UPDATE TO DROP THE ADVISORY FOR THE NRN MTS/POCONOS. ONLY A FEW FLURRIES WILL BE LEFT THERE...AS LOW IS WELL TO THE EAST AND INVERSION LOWERING SFC PRESSURES RISING. WILL TWEAK JUST THE FIRST PD WORDING FOR NOW. ALSO RE-ISSUED THE WSW FOR NOW...WITH LIGHT SNOW CONTINUING AS THE UPSLOPE AND CROSS-LAKE FETCH CONTINUES. SO WILL JUST CONTINUE THEM FOR NOW. && .PREV DISCUSSION... /ISSUED 1012 PM EST TUE JAN 30 2007/ SHORT TERM /THROUGH TUESDAY NIGHT/... WILL SEND OUT A QUICK...LATE EVENING ZONE UPDATE TO FRESHEN UP THE WORDING FOR SNOW SHOWERS ACROSS THE REGION. ARCTIC FRONT HAS PUSHED EAST OF THE SUSI VALLEY...TAKING THE HEAVY SQUALLS WITH IT. WEAKENING MID LEVEL DEFORMATION SNOWS ACROSS THE NCENT MTNS WILL BRING ANOTHER INCH OR TWO TO SOME LOCATIONS OVER THE NEXT FEW HOURS WITHIN THE SNOW ADVISORY...WHICH SET TO EXPIRE AT MIDNIGHT EST. PERSISTENT LAKE EFFECT/OROGRAPHIC SNOWS ACROSS THE NW MTNS AND LAUREL HIGHLANDS RESPECTIVELY WILL CONTINUE TO ACCUMULATE A FEW MORE INCHES OVERNIGHT...SO NO CHANGES TO THE LAKE EFFECT/SNOW ADVISORIES FOR THOSE AREAS. ELSEWHERE...EXPECT FLURRIES AND A BRIEF HEAVIER SNOW SHOWER OVERNIGHT AS THE PRIMARY 700-500 HPA THERMAL TROUGH MOVES SE FROM THE GLAKES. ACCUMULATIONS WILL BE LESS THAN AN INCH ACROSS THE CENTRAL RIDGE AND VALLEY REGION. OVC LAYER WILL BREAK UP AFTER MIDNIGHT ACROSS THE LOWER SUSQ VALLEY AS DRIER DEWPOINTS IN THE UPPER SINGLE DIGITS ADVECT EAST VIA A DOWNSLOPE LLVL FLOW. TRIMMED HOURLY AND MIN TEMPS OVERNIGHT BY 2-4 DEG F IN MANY LOCATIONS. PREV DISCUSSION... /ISSUED 728 PM EST TUE JAN 30 2007/ SHORT TERM /THROUGH TONIGHT/... AREA OF INSTABILITY WITH TOTAL TOTALS NEAR 50 CROSSING THE SUSQ VALLEY...ALONG WITH A RATHER STRONG...ALBEIT COMPACT UPPER SHORT WAVE MOVE EAST OVER THE NCENT MTNS WILL BRING NUMEROUS SNOW SHOWERS AND LOCALLY HEAVY SNOW SQUALLS EARLY TONIGHT. ISSUED A SNOW ADVISORY ACROSS THE NCENT MTNS THROUGH MIDNIGHT WHERE A MESO-B MID LVL DEFORMATION ZONE AND CORRESPONDING EAST/WEST BELT OF ENHANCED 850-700 HPA OMEGA WILL LEAD TO SEVERAL INCHES OF NEW SNOW. SNOW SHOWERS AND SQUALLS WILL DIMINISH TO SCATTERED FLURRIES ACROSS THE CENTRAL VALLEYS AND SUSQ RIVER VALLEY LATE THIS EVENING. PREV DISCUSSION... /ISSUED 325 PM EST TUE JAN 30 2007/ SHORT TERM /TONIGHT THROUGH WEDNESDAY/... MESO ANAL SHOWS SFC LOW JUST WEST OF BFD AT 18Z...WITH THE COLD FRONT MOVING THRU SWRN PA. RUC SHOWS A POCKET OF RELATIVELY UNSTABLE AIR...LOW-MID LEVEL LAPSE RATES IN EXCESS OF 6C/KM AND T-TOTALS TOPPING 50...HELPING TRIGGER THE CURRENT SNOW SHOWERS AND SQUALLS MOVING ACROSS THE AREA. THE BEST FORCING/INSTABILITY STARTS TO WANE AFTER ABOUT 21Z ACCORDING TO SHORT TERM GUIDANCE...WITH THE FRONT EXPECTED TO CLEAR MY EASTERN ZONES BY 00Z. AFTER THE FROPA...WE WILL TRANSITION INTO A MORE TYPICAL NW FLOW REGIME WITH LAKE EFFECT AND OROGRAPHICALLY FORCED SNOWS IN THE WEST...AND ACTIVITY TAPERING OFF TO JUST SCATTERED SNOW SHOWERS AND FLURRIES THE FURTHER DOWNWIND OF THE LAKES AND LAURELS ONE GETS. ONLY CONCERN IS A HINT IN THE MODELS THAT THE UPPER-AIR PORTION OF THE OCCLUDED FRONT HANGS TOUGH FOR A TIME INTO NW PA...ENHANCING THE CONVERGENCE THERE INTO THE EVENING. THIS SHOWS UP AS A WELL DEFINED THERMAL RIDGE UP THRU ABOUT 850MB IN ALL THE SHORT RANGE GUIDANCE. THEY SHIFT THIS EAST OF THE AREA AFTER 03Z. WEDNESDAY WILL SEE CONDITIONS IMPROVING AS INVERSION HEIGHTS LOWER THROUGHOUT THE DAY. THE BEST CHANCE OF LINGERING SNOW WILL BE OVER WESTERN HIGH TERRAIN. ELSEWHERE WE SHUD SEE LITTLE MORE THAN FLURRIES. LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... UPPER TROFFING OVER EASTERN NORTH AMERICA LOOKS TO DOMINATE THE LONG TERM PERIOD. THIS WILL LEAD TO NEAR TO BELOW NORMAL TEMPERATURES EARLY IN THE PERIOD AND POSSIBLY SIGNIFICANTLY BELOW NORMAL TEMPERATURES LATE IN THE PERIOD. MOST OF THE PERIOD LOOKS DRY...BUT TWO OPPORTUNITIES FOR PCPN STAND OUT. A WEATHER SYSTEM THAT HAS BEEN ADVERTISED FOR SEVERAL DAYS TO AFFECT THE REGION LATE THURSDAY INTO FRIDAY CONTINUES TO LOOK COMPLEX...WITH VARYING RUN TO RUN MODEL SOLUTIONS. A SOUTHERN STREAM TROF IS FORECAST TO INDUCE CYCLOGENESIS OVER THE SOUTHEAST U.S. THURSDAY NIGHT WITH A NORTHERN STREAM TROF FORECAST TO SWING THROUGH THE REGION LATER FRIDAY. MUCH YET DEPENDS ON THE TRACK OF THE COASTAL LOW AND ANY PHASING THAT MAY TAKE PLACE BETWEEN THE TWO STREAMS. AT THIS TIME...THERE IS A HIGH PROBABILITY OF MEASURABLE ACROSS ALL OF THE CWA...WITH POTENTIAL FOR A SEVERAL INCH SNOWFALL ACROSS THE REGION...EVEN THE LOWER SUSQUEHANNA VALLEY...WHERE SNOWFALL SO FAR THIS SEASON IS LESS THAN AN INCH TOTAL. A PRONOUNCED ARCTIC TROF IS FORECAST TO MOVE THROUGH THE FORECAST AREA ON MONDAY...POTENTIALLY BRINGING IN THE COLDEST AIR YET THIS WINTER. AVIATION /20Z-18Z/... THE AFTERNOON`S WIDESPREAD IFR CAUSED BY THE SHORTWAVE AND SNOW SHOWERS SHUD BEGIN TO IMPROVE IN MOST AREAS THIS EVENING AS THE UPPER TROF MOVES EAST OF THE REGION AND A WEST-NORTHWEST FLOW DEVELOPS. LIKE A BROKEN RECORD THOUGH...JST/BFD WILL NOT SHARE IN THE IMPROVEMENT AS UPSLOPE AND PROXIMITY TO LAKE ERIE CONSPIRE TO KEEP BOTH TERMINALS MAINLY DOWN BELOW 3000/3 WITH FREQUENT SNOW SHOWERS BRINGING EVEN LOWER CONDITIONS. WILL PROB SEE AOO/UNV/IPT IMPROVE TO MVFR CEILINGS AND MOSTLY UNLIMITED VIS WITH ONLY OCNL SNOW SHOWERS BRINGING BRIEFLY REDUCED VIS AFTER 00Z...WITH VFR DEVELOPING SLOWLY LATER TONIGHT INTO EARLY WED MORNING. STILL A QUESTION AS TO WHETHER THE FAR SERN TERMINALS WILL SEE MUCH INCLEMENT WX AT ALL AS THE SYSTEM IS ALREADY MOISTURE STARVED AND DOWN-SLOPING FLOW WILL ONLY HELP IN MAKING MUCH OF THE SNOW SHOWER ACTIVITY DRY UP BEFORE IT MAKES IT INTO THE LOWER SUSQ VALLEY. THINK THERE IS A CHC OF SNOW SHOWERS AND BRIEFLY LOWER CONDITIONS THRU THE EVENING...BUT AFTER THAT CIG/VIS SHUD NOT POSE MUCH OF A CHALLENGE THERE. && .CTP WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR PAZ004-005-010. SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR PAZ024-033. && $$ SHORT TERM...DANGELO pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 1152 PM CST TUE JAN 30 2007 .UPDATE... LATEST SURFACE ANALYSIS INDICATES TEMPERATURES ACROSS THE BIG COUNTRY HAVE FALLEN A LITTLE FASTER THAN WE WERE ANTICIPATING. THE STRATUS...CURRENTLY MOVING NORTH ACROSS THE CONCHO VALLEY...WILL LIKELY NOT MAKE IT INTO THE BIG COUNTRY FOR ANOTHER COUPLE HOURS. THUS...JUST SENT AN UPDATE TO LOWER OVERNIGHT LOWS A COUPLE DEGREES...MAINLY ACROSS THE BIG COUNTRY. ALSO...ADJUSTED SKY CONDITIONS FOR THE REMAINDER OF TONIGHT. AS FOR PRECIPITATION FOR THE REMAINDER OF TONIGHT...LATEST RUC SOUNDING DATA SUGGESTS COLUMN OVER THE BIG COUNTRY WILL CONTINUE TO SATURATE AND REMAIN AT OR JUST BELOW THE FREEZING MARK UNTIL AROUND 12Z. THEN...A WARMER LAYER...CENTERED AROUND 800 MB...EDGES A COUPLE DEGREES C ABOVE FREEZING. SO...DECIDED TO MAINTAIN THE MENTION OF SNOW FOR THE REMAINDER OF TONIGHT ACROSS THE BIG COUNTRY. HOWEVER...AS BEFORE...WE EXPECT LITTLE OR NO ACCUMULATION. ELSEWHERE...LIQUID PRECIPITATION STILL LOOKS BEST. 23/HUBER && .PREV DISCUSSION... /ISSUED 1127 PM CST TUE JAN 30 2007/ AVIATION... AREAS OF MVFR CIGS OF BKN010-020 ARE EXPECTED TO DEVELOP ACROSS WEST CENTRAL TEXAS AFTER 31/11Z...WITH MVFR CIGS BECOMING MORE WIDESPREAD AFTER 31/14Z. SCT SHRA WILL DEVELOP ACROSS WEST CENTRAL TEXAS AFTER 31/09Z...POSSIBLY MIXED WITH SLEET AND SNOW ACROSS THE BIG COUNTRY UNTIL 31/18Z. ALSO...SURFACE WINDS WILL BECOME SOUTHERLY AT 10 TO 15 KNOTS LATE TONIGHT AND WEDNESDAY. 21 PREV DISCUSSION... /ISSUED 914 PM CST TUE JAN 30 2007/ UPDATE... LATEST SATELLITE AND WSR-88D DATA INDICATE THE POTENTIAL FOR SHOWERS ACROSS THE NORTHERN BIG COUNTRY...WITH THE BEST RADAR RETURN CURRENTLY OVER HASKELL COUNTY AND THROCKMORTON COUNTY. SURFACE WINDS ACROSS WEST CENTRAL TEXAS REMAIN MAINLY NORTHEAST. HOWEVER...LATEST RUC DATA INDICATE WINDS WILL BECOME SOUTHEAST OVERNIGHT. THUS...CURRENT FORECAST LOOKS ON TRACK. 23/HUBER PREV DISCUSSION... /ISSUED 327 PM CST TUE JAN 30 2007/ SHORT TERM... UPPER LEVEL CLOUDS WERE REDEVELOPING FROM THE WEST WITH UPSLOPE FLOW BEHIND COLD FRONT THIS AFTERNOON (AT LEAST SOUTH OF INTERSTATE 20). WATER VAPOR LOOP INDICATED UPPER LEVEL LOW WAS OVER SOUTHERN CALIFORNIA...WITH SOME LIFT INDICATED AHEAD OF THE SYSTEM OVER ARIZONA AND NEW MEXICO. MID LEVEL MOISTURE INCREASES LATE TONIGHT AS UPPER LEVEL LOW SHEARS OUT AND MOVES TOWARD THE REGION...AND RIDING OVER THE COLD FRONT. MAY SEE SOME LIGHT PRECIPITATION TOWARD MORNING. GFS FORECAST SOUNDING INDICATE THIS TO BE SNOW OR SNOW/RAIN MIXTURE IN THE BIG COUNTRY...IF IT OCCURS. DO NOT ANTICIPATED ACCUMULATIONS. WENT A LITTLE LOWER ON TEMPERATURES (FROM MAV GUIDANCE) ACROSS THE BIG COUNTRY WHERE IT MAY TAKE A LITTLE LONGER FOR CLOUD COVER TO COME IN TONIGHT. LONG TERM... BEST SHORTWAVE/LIFT COMES IN WEDNESDAY TONIGHT. TEMPERATURES PROFILES INDICATE THIS TO BE MAINLY RAIN...THROUGH ITS POSSIBLE SOME SLEET MAY OCCUR IN NORTHERN SECTIONS OF THE BIG COUNTRY. RAIN CHANCES TAPER OFF THURSDAY MORNING. NEXT COLD FRONT COMES IN ON FRIDAY...KEEPING TEMPERATURES ON THE COOL SIDE THIS WEEKEND. MOISTURE TOO SHALLOW FOR ANY SIGNIFICANT RAIN THIS WEEKEND...THOUGH CANT RULE OUT A SPRINKLE OR TWO. ECMWF DIFFER IN HANDLING ANOTHER COLD FRONT NEXT WEEK. ECMWF HAS COLD FRONT MONDAY...WHICH BUILDS IN VERY STRONGLY THROUGH TUESDAY. THE GFS PUSHES MOST OF THE COLD AIR TO THE EAST ON MONDAY...WITH ONLY A WEAKER COLD FRONT. IT THEN BRINGS WEST CENTRAL TEXAS IN SOUTHERLY WARM ADVECTION TUESDAY...BEFORE A SECOND STRONG COLD FRONT MOVES IN TUESDAY NIGHT. WILL GO WITH THE COLDER ECMWF SOLUTION FOR NOW...AS A LOT OF TIMES FRONT GETS CHANNELS AGAINST THE ROCKY MOUNTAINS. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 29 48 37 48 / 20 30 50 20 SAN ANGELO 34 51 40 55 / 20 20 50 20 JUNCTION 37 49 44 60 / 20 20 50 20 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/23 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 1127 PM CST TUE JAN 30 2007 .AVIATION... AREAS OF MVFR CIGS OF BKN010-020 ARE EXPECTED TO DEVELOP ACROSS WEST CENTRAL TEXAS AFTER 31/11Z...WITH MVFR CIGS BECOMING MORE WIDESPREAD AFTER 31/14Z. SCT SHRA WILL DEVELOP ACROSS WEST CENTRAL TEXAS AFTER 31/09Z...POSSIBLY MIXED WITH SLEET AND SNOW ACROSS THE BIG COUNTRY UNTIL 31/18Z. ALSO...SURFACE WINDS WILL BECOME SOUTHERLY AT 10 TO 15 KNOTS LATE TONIGHT AND WEDNESDAY. 21 && .PREV DISCUSSION... /ISSUED 914 PM CST TUE JAN 30 2007/ UPDATE... LATEST SATELLITE AND WSR-88D DATA INDICATE THE POTENTIAL FOR SHOWERS ACROSS THE NORTHERN BIG COUNTRY...WITH THE BEST RADAR RETURN CURRENTLY OVER HASKELL COUNTY AND THROCKMORTON COUNTY. SURFACE WINDS ACROSS WEST CENTRAL TEXAS REMAIN MAINLY NORTHEAST. HOWEVER...LATEST RUC DATA INDICATE WINDS WILL BECOME SOUTHEAST OVERNIGHT. THUS...CURRENT FORECAST LOOKS ON TRACK. 23/HUBER PREV DISCUSSION... /ISSUED 327 PM CST TUE JAN 30 2007/ SHORT TERM... UPPER LEVEL CLOUDS WERE REDEVELOPING FROM THE WEST WITH UPSLOPE FLOW BEHIND COLD FRONT THIS AFTERNOON (AT LEAST SOUTH OF INTERSTATE 20). WATER VAPOR LOOP INDICATED UPPER LEVEL LOW WAS OVER SOUTHERN CALIFORNIA...WITH SOME LIFT INDICATED AHEAD OF THE SYSTEM OVER ARIZONA AND NEW MEXICO. MID LEVEL MOISTURE INCREASES LATE TONIGHT AS UPPER LEVEL LOW SHEARS OUT AND MOVES TOWARD THE REGION...AND RIDING OVER THE COLD FRONT. MAY SEE SOME LIGHT PRECIPITATION TOWARD MORNING. GFS FORECAST SOUNDING INDICATE THIS TO BE SNOW OR SNOW/RAIN MIXTURE IN THE BIG COUNTRY...IF IT OCCURS. DO NOT ANTICIPATED ACCUMULATIONS. WENT A LITTLE LOWER ON TEMPERATURES (FROM MAV GUIDANCE) ACROSS THE BIG COUNTRY WHERE IT MAY TAKE A LITTLE LONGER FOR CLOUD COVER TO COME IN TONIGHT. LONG TERM... BEST SHORTWAVE/LIFT COMES IN WEDNESDAY TONIGHT. TEMPERATURES PROFILES INDICATE THIS TO BE MAINLY RAIN...THROUGH ITS POSSIBLE SOME SLEET MAY OCCUR IN NORTHERN SECTIONS OF THE BIG COUNTRY. RAIN CHANCES TAPER OFF THURSDAY MORNING. NEXT COLD FRONT COMES IN ON FRIDAY...KEEPING TEMPERATURES ON THE COOL SIDE THIS WEEKEND. MOISTURE TOO SHALLOW FOR ANY SIGNIFICANT RAIN THIS WEEKEND...THOUGH CANT RULE OUT A SPRINKLE OR TWO. ECMWF DIFFER IN HANDLING ANOTHER COLD FRONT NEXT WEEK. ECMWF HAS COLD FRONT MONDAY...WHICH BUILDS IN VERY STRONGLY THROUGH TUESDAY. THE GFS PUSHES MOST OF THE COLD AIR TO THE EAST ON MONDAY...WITH ONLY A WEAKER COLD FRONT. IT THEN BRINGS WEST CENTRAL TEXAS IN SOUTHERLY WARM ADVECTION TUESDAY...BEFORE A SECOND STRONG COLD FRONT MOVES IN TUESDAY NIGHT. WILL GO WITH THE COLDER ECMWF SOLUTION FOR NOW...AS A LOT OF TIMES FRONT GETS CHANNELS AGAINST THE ROCKY MOUNTAINS. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 31 48 37 48 / 20 30 50 20 SAN ANGELO 34 51 40 55 / 20 20 50 20 JUNCTION 37 49 44 60 / 20 20 50 20 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 954 AM EST WED JAN 31 2007 .DISCUSSION... CURRENT...WRN ATLC LOW PRES HAS DRAGGED A WEAK FRONTAL TROUGH ACROSS NRN/CTRL FL. DUE TO DVLPG LOW PRES OVER THE WRN GOMEX THE TROUGH HAS SLOWED CONSIDERABLY AND IS ALREADY FALLING APART AS I TYPE. NORTH OF THIS DISSIPATING FEATURE...EXPANSIVE SFC HIGH PRES RIDGE HAS MOVED INTO THE MID MS/OH/TN VLYS. MORNING RAOBS/RUC ANLYS FIELDS INDICATE THE LARGE SWATH OF >90% H70-H50 RH WHICH MOVED OVER THE STATE LAST NIGHT...PRODUCING NMRS SPRINKLES IS MOVING OFF TO THE EAST. FIRST HR OR SO OF VIS SATELLITE IMAGERY SHOWS THAT LAST NIGHT`S EXTENSIVE MID LEVEL CLOUD CANOPY IS THINNING OUT QUITE A BIT ATTM. TODAY...EXPECT ENOUGH BREAKS TO DEVELOP THIS AFTN FOR SKIES TO WIND UP AVGING "PSUNNY"...HOWEVER WILL KEEP AN EYE ON WHAT APPEARS TO BE A WEAK LOW/MID LEVEL VORT IN THE GOMEX BTWN BUOYS 42001/42003 TO SEE IF IT MIGHT HAVE THE POTENTIAL SPREAD ADDITIONAL CLOUDS THIS WAY BY LATE AFTN...BUT FOR NOW IT APPEARS THAT THIS WON`T BE THE CASE. GIVEN THIS...WE SHOULD WIND REACHING FCSTR MAX TEMPS CWA-WIDE...AND DON`T SEE A PRESSING NEED FOR A ZFP UPDATE. && .AVIATION...VFR WITH DCRSG COVRG OF BKN MID LEVEL CIGS. && .MARINE...LATEST BUOY OBS CONTINUE TO SHOW N-NNW WINDS OF 15-20KT. NEAR SHORE. OVER THE LAST 2HR...SCRIPPS BUOY 41114 (OFFSHORE FPR) HAS ACTUALLY NUDGED INTO THE 3-4FT RANGE...ABOVE THE CURRENT FCST. ALL INDICATIONS FOR THE SHORT RANGE GUIDANCE IS THAT THE LOCAL PGRAD WILL SLACKEN THIS AFTN...ALLOWING WINDS TO DROP OFF TO 10-15KT AS THE FLOW VEERS FROM N TO NE. HOWEVER...GIVEN THE CURRENT CONDS... PLAN TO KEEP CAUTIONARY STMT FOR THE FLG-COF 20-60NM LEG GOING THRU EARLY AFTN. WILL ALSO TWEAK SEAS OVER THE 0-20NM COF-JUP LEG UP TO 2-4FT TO ACCT FOR CURRENT CONDS. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ CRISTALDI fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 1107 AM EST WED JAN 31 2007 .MORNING UPDATE... DOING A QUICK UPDATE TO REMOVE MORNING WORDING. LOWERED HIGH TEMPS A FEW DEGREES TODAY AS HOURLIES WERE RUNNING A BIT COOLER THAN WHAT THE GRIDS REFLECTED. SHOULD BE MOSTLY SUNNY AND TEMPS WILL WARM UP TO THE MID AND UPPER 20S...WITH NEAR FREEZING TEMPS ACROSS SRN KY UNDER HIGH PRESSURE. SINCE THE WINDS ARE LIGHT...WIND CHILLS NOT A FACTOR TODAY DESPITE IT BEING COLD. CLOUDS WILL BE ON THE INCREASE LATER THIS AFTERNOON...WITH MID TO UPPER LEVEL CLOUDS FILTERING IN DOWNSTREAM OF GULF COAST SYSTEM. UPDATE OUT SHORTLY. AL && .PREV DISCUSSION... SHORT TERM (TODAY-FRIDAY)... TODAY... SCT STRATOCU CURRENTLY FROM NEAR CVG TO SDF TO OWB FCST TO SLIDE ESE THROUGH THE EARLY MORNING HOURS. A COUPLE FLURRIES NOT OUT OF THE QUESTION ASSOC WITH THESE CLOUDS. MOST OF THE CWA WILL START OFF PARTLY CLOUDY BEFORE DAWN...BUT QUICKLY GO SUNNY THIS MORNING. TEMPS WILL BE QUITE COLD...MOST LOCATIONS IN THE LOWER TEENS TO UPPER SINGLE DIGITS. HOWEVER HIGH PRES MOVING INTO THE AREA WILL RESULT IN LIGHT WESTERLY WINDS...SO WIND CHILLS WILL NOT BE A SIGNIFICANT PROBLEM. THERE IS AN APPRECIABLE SPREAD IN THE MOS GUIDANCE FOR HIGH TEMPS TODAY...BIGGEST AT LEX WHERE NAM-MOS SHOWS 27 WHILE GFS-MOS PREDICTS A HIGH OF 35! NGM NUMBERS ARE CLOSER TO COOLER NAM-MOS. A BLEND OF RAW GFS/NAM DATA YIELD HIGHS RANGING FROM THE UPPER 20S FAR NORTHEAST TO THE MIDDLE 30S IN THE SOUTHWEST...AND THIS SEEMS REASONABLE. CS TONIGHT-FRIDAY... THE TIMING AND AMOUNTS OF WINTERY PRECIP ARE THE MAIN CONCERNS FOR LATE TONIGHT THROUGH FRIDAY MORNING. UPPER AIR PATTERN WILL HAVE A BROAD POSITIVELY TILTED TROUGH CENTERED ACROSS THE ROCKIES...WITH ZONAL FLOW DOWNSTREAM ACROSS THE SOUTHERN STATES. WITH THIS PATTERN...ANY UPPER AIR DISTURBANCES WILL BE QUITE SHEARED IN A CONFLUENT UPPER PATTERN ACROSS THE LOWER OHIO VALLEY. ONE THING TO NOTE IS A SHARPENING JET STREAK THAT WILL DEVELOP AND MOVE ACROSS THE TENNESSEE VALLEY EARLY THURSDAY. LIFT ASSOCIATED WITH THE LEFT FRONT QUADRANT OF THIS JET WILL MOVE ACROSS THE LOWER OHIO VALLEY AND PROVIDE A CHANCE OF SNOW BEGINNING EARLY THURSDAY. AT THE SURFACE...ARCTIC HIGH PRESSURE WILL MOVE OFF THE MID ATLANTIC SEABOARD EARLY THURSDAY. THIS WILL ALLOW SOUTHWESTERLY MID LEVEL FLOW TO RESUME ABOVE COLDER AIR IN PLACE WITHIN THE BOUNDARY LAYER. MAIN AXIS OF MOISTURE WILL REMAIN SOUTH...WHERE PLENTY OF RAIN IS EXPECTED ACROSS THE NORTHERN GULF STATES ASSOCIATED WITH AN ELEVATED WARM FRONT. FARTHER NORTH...LIFT WILL OCCUR WITH MUCH LESS MOISTURE AVAILABLE AND WILL BE A RESULT OF UPPER AIR DYNAMICS. BOTH ETA AND GFS HINT AT POSSIBLY TWO SEPARATE EPISODES OF WINTERY PRECIPITATION. THE FIRST WILL MOVE ACROSS OUR CWA EARLY THURSDAY...AND THE SECOND...LATE THURSDAY AND EARLY FRIDAY. FORECAST SOUNDINGS SHOW BASICALLY ALL OF CENTRAL KENTUCKY COLD ENOUGH FOR ALL SNOW WITH THIS FIRST EPISODE. MOISTURE WILL BE SCANT...BUT WITH RAIN/SNOW RATIOS GREATER THAN 10 TO 1 SOME LIGHT ACCUMULATIONS... PERHAPS AN INCH OR TWO...LOOK LIKELY. INITIALLY...VERY DRY LOW LEVEL AIR WILL BE IN PLACE EARLY THURSDAY...THIS I THINK WILL HELP KEEP PRECIP ALL SNOW AT THE BEGINNING...BUT ALSO MAY DELAY THE ONSET...WHICH SHOULD BE DURING THE PRE-DAWN HOURS. BY LATE THURSDAY...A WEAK UPPER AIR DISTURBANCE IS FORECAST BY BOTH THE NAM AND THE GFS TO MOVE ACROSS OUR REGION. A SECOND ROUND OF LIGHT PRECIP WILL BE ASSOCIATED WITH THIS...BUT WARMER BOUNDARY LAYER TEMPERATURES ACROSS THE SOUTHERN THIRD OF KENTUCKY MAY ALLOW SOME RAIN TO MIX IN WITH THE SNOW. ANY SNOW AMOUNTS WITH THIS WILL BE LIGHT AS WELL...WITH SNOW ACCUMULATIONS POSSIBLY APPROACHING ONE INCH. WIND WILL SHIFT TO THE WEST FRIDAY AFTERNOON AS A SURFACE TROUGH MOVES ACROSS THE GREAT LAKES. COLDER AIR WILL ARRIVE FRIDAY AFTERNOON AS FLURRIES WILL BE ENDING. TEMPERATURES WILL MODERATE THURSDAY AFTERNOON INTO FRIDAY MORNING...WITH HIGHS AS WARM AS THE MID 30S THURSDAY AFTERNOON ACROSS THE SOUTH. JSD LONG TERM (SATURDAY-TUESDAY)... DEEP POLAR VORTEX JUST SOUTHWEST OF HUDSON`S BAY WILL KEEP VERY COLD AIR LOCKED IN PLACE ACROSS THE UPPER MIDWEST AND THE GREAT LAKES. COLD AIR WILL BE IN PLACE ACROSS THE REGION SATURDAY AS HIGH PRESSURE MOVES INTO THE SOUTHERN PLAINS. FRIGID AIR WILL ARRIVE LATE SATURDAY AND CONTINUE THROUGH TUESDAY TWO ARCTIC FRONTS ARE FORECAST TO MOVE THROUGH KENTUCKY...ONE LATE SATURDAY AND THE SECOND ONE EARLY MONDAY. IT`S POSSIBLE THAT MONDAY AND TUESDAY WILL HAVE THE COLDEST TEMPERATURES SINCE LATE DECEMBER 2004. JSD AVIATION (12Z TAFS)... BAND OF STRATOCU HAS BEEN PERSISTENT...CURRENTLY POSITIONED FROM NEAR SDF TO LEX. BASED ON SATELLITE TRENDS AND LATEST RUC RH FIELDS...EXPECT CLOUDS TO PROGRESS OFF TO THE ESE AFFECTING THE SDF TAF SITE THROUGH 12-13Z...LEX THROUGH 14Z. CIGS ARE NOT TOO LOW... AROUND 2.5KFT. A FEW FLURRIES POSSIBLE WITHIN THIS BAND OF CLOUDS BUT VSBYS WILL BE UNRESTRICTED. VFR/SKC FROM MID MORNING INTO THE AFTN HOURS AT ALL TAF SITES. MID/HIGH LEVEL CLOUDS FCST TO MOVE INTO THE REGION TOWARD 21Z...WITH CIGS DROPPING BELOW 10KFT AFTER 0Z. BASED ON LATEST NAM BUFKIT DATA...WILL INTRODUCE -SN AFTER 6Z FROM SW TO NE...BUT WILL KEEP CIGS AOA 2KFT THROUGH 12Z/THU. CS && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 605 AM EST WED JAN 31 2007 .AVIATION (12Z TAFS)... BAND OF STRATOCU HAS BEEN PERSISTENT...CURRENTLY POSITIONED FROM NEAR SDF TO LEX. BASED ON SATELLITE TRENDS AND LATEST RUC RH FIELDS...EXPECT CLOUDS TO PROGRESS OFF TO THE ESE AFFECTING THE SDF TAF SITE THROUGH 12-13Z...LEX THROUGH 14Z. CIGS ARE NOT TOO LOW... AROUND 2.5KFT. A FEW FLURRIES POSSIBLE WITHIN THIS BAND OF CLOUDS BUT VSBYS WILL BE UNRESTRICTED. VFR/SKC FROM MID MORNING INTO THE AFTN HOURS AT ALL TAF SITES. MID/HIGH LEVEL CLOUDS FCST TO MOVE INTO THE REGION TOWARD 21Z...WITH CIGS DROPPING BELOW 10KFT AFTER 0Z. BASED ON LATEST NAM BUFKIT DATA...WILL INTRODUCE -SN AFTER 6Z FROM SW TO NE...BUT WILL KEEP CIGS AOA 2KFT THROUGH 12Z/THU. CS .SHORT TERM (TODAY-FRIDAY)... TODAY... SCT STRATOCU CURRENTLY FROM NEAR CVG TO SDF TO OWB FCST TO SLIDE ESE THROUGH THE EARLY MORNING HOURS. A COUPLE FLURRIES NOT OUT OF THE QUESTION ASSOC WITH THESE CLOUDS. MOST OF THE CWA WILL START OFF PARTLY CLOUDY BEFORE DAWN...BUT QUICKLY GO SUNNY THIS MORNING. TEMPS WILL BE QUITE COLD...MOST LOCATIONS IN THE LOWER TEENS TO UPPER SINGLE DIGITS. HOWEVER HIGH PRES MOVING INTO THE AREA WILL RESULT IN LIGHT WESTERLY WINDS...SO WIND CHILLS WILL NOT BE A SIGNIFICANT PROBLEM. THERE IS AN APPRECIABLE SPREAD IN THE MOS GUIDANCE FOR HIGH TEMPS TODAY...BIGGEST AT LEX WHERE NAM-MOS SHOWS 27 WHILE GFS-MOS PREDICTS A HIGH OF 35! NGM NUMBERS ARE CLOSER TO COOLER NAM-MOS. A BLEND OF RAW GFS/NAM DATA YIELD HIGHS RANGING FROM THE UPPER 20S FAR NORTHEAST TO THE MIDDLE 30S IN THE SOUTHWEST...AND THIS SEEMS REASONABLE. CS TONIGHT-FRIDAY... THE TIMING AND AMOUNTS OF WINTERY PRECIP ARE THE MAIN CONCERNS FOR LATE TONIGHT THROUGH FRIDAY MORNING. UPPER AIR PATTERN WILL HAVE A BROAD POSITIVELY TILTED TROUGH CENTERED ACROSS THE ROCKIES...WITH ZONAL FLOW DOWNSTREAM ACROSS THE SOUTHERN STATES. WITH THIS PATTERN...ANY UPPER AIR DISTURBANCES WILL BE QUITE SHEARED IN A CONFLUENT UPPER PATTERN ACROSS THE LOWER OHIO VALLEY. ONE THING TO NOTE IS A SHARPENING JET STREAK THAT WILL DEVELOP AND MOVE ACROSS THE TENNESSEE VALLEY EARLY THURSDAY. LIFT ASSOCIATED WITH THE LEFT FRONT QUADRANT OF THIS JET WILL MOVE ACROSS THE LOWER OHIO VALLEY AND PROVIDE A CHANCE OF SNOW BEGINNING EARLY THURSDAY. AT THE SURFACE...ARCTIC HIGH PRESSURE WILL MOVE OFF THE MID ATLANTIC SEABOARD EARLY THURSDAY. THIS WILL ALLOW SOUTHWESTERLY MID LEVEL FLOW TO RESUME ABOVE COLDER AIR IN PLACE WITHIN THE BOUNDARY LAYER. MAIN AXIS OF MOISTURE WILL REMAIN SOUTH...WHERE PLENTY OF RAIN IS EXPECTED ACROSS THE NORTHERN GULF STATES ASSOCIATED WITH AN ELEVATED WARM FRONT. FARTHER NORTH...LIFT WILL OCCUR WITH MUCH LESS MOISTURE AVAILABLE AND WILL BE A RESULT OF UPPER AIR DYNAMICS. BOTH ETA AND GFS HINT AT POSSIBLY TWO SEPARATE EPISODES OF WINTERY PRECIPITATION. THE FIRST WILL MOVE ACROSS OUR CWA EARLY THURSDAY...AND THE SECOND...LATE THURSDAY AND EARLY FRIDAY. FORECAST SOUNDINGS SHOW BASICALLY ALL OF CENTRAL KENTUCKY COLD ENOUGH FOR ALL SNOW WITH THIS FIRST EPISODE. MOISTURE WILL BE SCANT...BUT WITH RAIN/SNOW RATIOS GREATER THAN 10 TO 1 SOME LIGHT ACCUMULATIONS... PERHAPS AN INCH OR TWO...LOOK LIKELY. INITIALLY...VERY DRY LOW LEVEL AIR WILL BE IN PLACE EARLY THURSDAY...THIS I THINK WILL HELP KEEP PRECIP ALL SNOW AT THE BEGINNING...BUT ALSO MAY DELAY THE ONSET...WHICH SHOULD BE DURING THE PRE-DAWN HOURS. BY LATE THURSDAY...A WEAK UPPER AIR DISTURBANCE IS FORECAST BY BOTH THE NAM AND THE GFS TO MOVE ACROSS OUR REGION. A SECOND ROUND OF LIGHT PRECIP WILL BE ASSOCIATED WITH THIS...BUT WARMER BOUNDARY LAYER TEMPERATURES ACROSS THE SOUTHERN THIRD OF KENTUCKY MAY ALLOW SOME RAIN TO MIX IN WITH THE SNOW. ANY SNOW AMOUNTS WITH THIS WILL BE LIGHT AS WELL...WITH SNOW ACCUMULATIONS POSSIBLY APPROACHING ONE INCH. WIND WILL SHIFT TO THE WEST FRIDAY AFTERNOON AS A SURFACE TROUGH MOVES ACROSS THE GREAT LAKES. COLDER AIR WILL ARRIVE FRIDAY AFTERNOON AS FLURRIES WILL BE ENDING. TEMPERATURES WILL MODERATE THURSDAY AFTERNOON INTO FRIDAY MORNING...WITH HIGHS AS WARM AS THE MID 30S THURSDAY AFTERNOON ACROSS THE SOUTH. JSD .LONG TERM (SATURDAY-TUESDAY)... DEEP POLAR VORTEX JUST SOUTHWEST OF HUDSON`S BAY WILL KEEP VERY COLD AIR LOCKED IN PLACE ACROSS THE UPPER MIDWEST AND THE GREAT LAKES. COLD AIR WILL BE IN PLACE ACROSS THE REGION SATURDAY AS HIGH PRESSURE MOVES INTO THE SOUTHERN PLAINS. FRIGID AIR WILL ARRIVE LATE SATURDAY AND CONTINUE THROUGH TUESDAY TWO ARCTIC FRONTS ARE FORECAST TO MOVE THROUGH KENTUCKY...ONE LATE SATURDAY AND THE SECOND ONE EARLY MONDAY. IT`S POSSIBLE THAT MONDAY AND TUESDAY WILL HAVE THE COLDEST TEMPERATURES SINCE LATE DECEMBER 2004. JSD && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1056 AM EST WED JAN 31 2007 ...SEVERAL DAYS OF VERY COLD AIR EXPECTED THIS WEEKEND INTO EARLY NEXT WEEK... .SYNOPSIS... 15Z WATER VAPOR LOOP AND 12Z RAOBS SHOW WEAK RIDGING OCCURRING OVER UPPER MICHIGAN AHEAD OF A SHRTWV TROUGH WHICH EXTENDS FROM NW MINNESOTA INTO SE WYOMING. WARM ADVECTION MID AND HIGH CLOUDS CONTINUE TO BE GENERATED AHEAD OF THIS SHRTWV TROUGH...THOUGH VERY DRY AIR BETWEEN 650-900MB AS SEEN ON THE 12Z MPX...GRB AND INL SOUNDINGS HAVE KEPT SNOWFALL PRODUCTION AT A MINIMUM. IN FACT...THE ONLY SNOW OCCURRING IS BACK IN THE FARGO AREA...WHICH HAPPENS TO BE ON THE BACK SIDE OF A 1010MB LOW IN NW MINNESOTA. A TROUGH EXISTS TO THE E OF THE LOW...ACROSS CENTRAL LAKE SUPERIOR AND SE TO WHITEFISH BAY. KMQT RADAR LOOP CONTINUES TO SHOW SOME DECENT BANDS ALONG THIS TROUGH NEAR GRAND MARAIS EASTWARD ACROSS NORTHERN LUCE COUNTY. THE HOUGHTON COUNTY AIRPORT IS ALSO ON THE SOUTHERN EDGE OF THE BAND AS NOTED BY VISIBILITIES OF 1SM OR LESS FOR THE PAST 5 HOURS. HAVE MADE NUMEROUS CALLS TO COOP OBSERVERS THIS MORNING FOR VERIFICATION OF THE WARNINGS/ADVISORIES AND FOUND THAT SNOWFALL RATES WERE AS EXPECTED...BETWEEN 1 AND 2 INCHES AN HOUR. HOWEVER...GIVEN THAT THE CONVERGENT BANDS (WHICH LOOK DECENT ON VISIBLE SATELLITE IMAGERY RIGHT NOW) NEVER STAYED IN ONE PLACE FOR MORE THAN 4 HOURS...MOST OF THE AMOUNTS HAVE BEEN UNDER 6 INCHES IN THE PAST 12 HOURS. THE COMBINATION OF LAND BREEZES AND HEIGHT RISES AHEAD OF THE SHRTWV TROUGH HAVE HELPED TO PUSH THE TROUGH AND HEAVIER LES NORTHWARD... AND THIS TREND CAN BE OBSERVED IN THE LATEST RADAR LOOP. LASTLY... TO OUR N...THE POLAR VORTEX STILL SITS UP IN HUDSON BAY...THOUGH IS EXPECTED TO DROP S THIS WEEKEND TO BRING THE UPCOMING COLD WAVE. && .UPDATE... MAIN UPDATE CONCERN IS ONGOING HEADLINES. THE 12Z RUC SEEMED TO HAVE THE BEST HANDLE ON THE CURRENT PRESSURE FIELD AND CONVERGENT AREAS FOR THE PAST FEW HOURS...THUS HAVE FOLLOWED IT FOR THE UPDATE. THE SURFACE TROUGH IS PROGGED TO CONTINUE LIFTING NORTHWARD...WITH PERHAPS THE DEVELOPMENT OF A SURFACE LOW/MESO-LOW OVER CENTRAL LAKE SUPERIOR BY 00Z. THIS SHOULD HELP PULL MOST...IF NOT ALL THE LAKE EFFECT...OUT OF UPPER MICHIGAN. STILL KEPT SOME ISOLATED SNOW SHOWERS OVER KEWEENAW COUNTY AFTER 20Z IN THE EVENT THAT THE BAND IS SLOWER TO MOVE NORTH. AS FAR AS HEADLINES GO...WILL LET THEM EXPIRE ON SCHEDULE SINCE THERE STILL IS SOME DECENT SNOWFALL RATES OCCURRING WITH THE LAKE EFFECT BANDS. SNOW AMOUNTS AND QPF FORECAST LOOK ON TRACK. OUTSIDE OF THE LAKE EFFECT...MID AND HIGH CLOUDS ARE EXPECTED TO CONTINUE SPREADING ACROSS THE CWA SINCE WE REMAIN DOWNSTREAM OF THE NW MINNESOTA SHRTWV TROUGH. THESE CLOUDS WILL KEEP SOLAR INSOLATION LOW...HOWEVER A 5 TO 15 MPH SW WIND SHOULD ALLOW TEMPERATURES TO CLIMB TO GOING FORECAST HIGHS. NO CHANGES MADE TO TEMPS OR SKY COVER. GRID UPDATE...ARBWSWMQT AND ARBZFPMQT UPDATES ALREADY ISSUED. && .PREV DISCUSSION... MAIN FCST ISSUES REVOLVE AROUND ONGOING HEADLINE LES EVENT...ANOTHER POSSIBLE SIGNIFICANT LAKE EFFECT/LAKE ENHANCED EVENT FRI WITH SHORTWAVE PASSAGE...AND THEN THE VERY COLD AIR TO SETTLE OVER THE AREA IN ITS WAKE. WATER VAPOR IMAGERY AND GFS ANALYSIS SHOW A VERY PRONOUNCED RIDGE ALONG THE W COAST OF NAMERICA. 500MB HEIGHTS THERE ARE 2.5 STANDARD DEVIATIONS ABOVE NORMAL WHICH TRANSLATES TO 370M ABOVE NORMAL IN THE CORE OF THE ANOMALY OVER SE ALASKA/SRN YUKON. DOWNSTREAM TROF IS DOMINATING THE ERN 2/3RDS OF NAMERICA...AND THE TROF WILL ONLY BECOME DEEPER DUE TO THE UPSTREAM POSTIVE HEIGHT ANOMALY. IN THE NW FLOW...ONE SHORTWAVE WAS DROPPING SE THRU THE DAKOTAS WHILE ANOTHER WAS TRACKING SE JUST TO THE E OF LAKE SUPERIOR. THE LATTER SHORTWAVE HAS HELPED INTENSIFY LES OVER ERN LAKE SUPERIOR WHICH IS OCCURRING IN A CONVERGENCE ZONE BTWN WRLY WINDS OVER UPPER MI AND NW WINDS OVER THE LAKE. LES BANDS HAVE HAD A FAIR AMOUNT OF SEPARATION WHICH WILL LIMIT THE AREAL COVERAGE OF HIGHER ACCUMULATIONS. MOST INTENSE BANDS ARE WIDELY SEPARATED. SFC WIND FIELDS SHOW CONVERGENCE ZONE EXTENDING W ACROSS THE KEWEENAW (WIND DIRECTION WAS SSW AT ONTONAGON AND NW AT HOUGHTON). WOULD EXPECT SOME HEAVIER SNOW TO BE OCCURRING IN THE PAINESDALE VCNTY. EVEN SO...DRIER UPSTREAM AIRMASS PER 00Z KINL SOUNDING IS PROBABLY HAVING A NEGATIVE IMPACT ON SNOW INTENSITY OVER THE NW FCST AREA. WITH PASSAGE OF SHORTWAVE JUST E OF LAKE SUPERIOR...WINDS WILL VEER A BIT MORE ACROSS ERN LAKE SUPERIOR OVER THE NEXT FEW HRS...AND SPEEDS WILL DECREASE. THE VEERING WINDS OVER THE LAKE WILL CONTINUE TO FOCUS CONVERGENCE ACROSS ERN ALGER/NRN LUCE COUNTIES EARLY THIS MORNING WHILE CONVERGENCE ZONE TO THE NW WILL REMAIN NEARLY STATIONARY ACROSS CNTRL HOUGHTON COUNTY. FROM MID MORNING INTO THE AFTN...WINDS WILL BACK SW IN RESPONSE TO APPROACH OF THE NRN EXTENSION OF SHORTWAVE CURRENTLY OVER THE DAKOTAS. MODELS ARE ACTUALLY IN DECENT AGREEMENT ON THE WIND FIELD RESPONSE. IT APPEARS WINDS WILL BE SUFFICIENTLY BACKED TO END LES OVER ALGER/LUCE AROUND 18Z. SO...WILL ALLOW ONGOING WARNING FOR THAT AREA TO CONTINUE AS IS UNTIL EXPIRATION AT 18Z. WIDE SEPARATION BTWN STRONGEST LES BANDS WILL PROBABLY RESULT IN ONLY A FEW LOCATIONS REACHING THE WARNING CRITERIA OF 10 INCHES FOR THIS EVENT. MEANWHILE...THERE IS A BIT MORE UNCERTAINTY ON WIND FIELDS OVER/NEAR THE KEWEENAW DUE TO SMALL BUT IMPORTANT DIFFERENCES IN TIMING THE NWD MOVEMENT OF CONVERGENCE ZONE. HOWEVER...IT DOES APPEAR THAT BY LATE AFTN...MAIN CONVERGENCE WILL HAVE SHIFTED JUST N AND NW OF THE KEWEENAW. WITH WIND FIELDS DIMINISHING SUBSTANTIALLY THRU THE DAY AND THUS WEAKENING THE CONVERGENCE...WOULD EXPECT LES IN THE MAIN BAND TO DIMINISH AS IT LIFTS N ACROSS THE KEWEENAW. OF COURSE...THAT IS NOT ALWAYS THE CASE. IT LOOKS LIKE MUCH OF ONTONAGON/SRN HOUGHTON COUNTIES HAVE SEEN VERY LITTLE/NO SNOW. RECENT REPORT FROM MASS CITY WAS JUST LIGHT SNOW. PERHAPS THE AREA JUST N OF M-38 HAS SEEN SOME ACCUMULATION...BUT THERE IS NO WAY TO KNOW AT THIS TIME OF DAY. BASED ON THE SOLID SSW WIND AT ONTONAGON AND REPORT FROM MASS CITY...WILL DROP WARNING FOR ONTONAGON COUNTY AS CONVERGENCE AREA IS PROBABLY JUST N OF COUNTY. WILL THUS ALSO DROP SRN HOUGHTON COUNTY ADVY. NOT SURE WARNING WILL VERIFY FOR NRN HOUGHTON COUNTY...BUT WITH CONVERGENCE ZONE THERE...WILL LET IT RIDE. IT`S POSSIBLE THAT HEADLINE FOR KEWEENAW COUNTY MAY NEED TO BE EXTENDED BEYOND 18Z...BUT IT SEEMS REASONABLE AT THIS POINT TO SEE HOW THE WIND FIELDS ACTUALLY EVOVLE DURING THE MID/LATE MORNING BEFORE MAKING ANY NECESSARY HEADLINE ADJUSTMENTS. AWAY FROM LES...EXPECT DRY WEATHER TODAY. PASSAGE OF SHORTWAVE TONIGHT WILL RESULT IN WINDS VEERING MORE WRLY AGAIN OVER WRN LAKE SUPERIOR. IF A BAND OF HEAVIER LES REMAINS INTO THE EVENING OVER THE LAKE IN THE CONVERGENT ZONE THAT LIFTED N TODAY...IT WILL MOVE BACK ONSHORE OVER THE KEWEENAW. WHILE GFS FCST SOUNDING FOR KCMX INDICATES MIDLEVEL DRYING AND INVERSION SETTLING DOWN TO 4-5KFT...NAM LOOKS MORE PROMISING FOR HEAVIER SNOW WITH INVERSION AT 6-7KFT AND DEEP LAYER OF FAVORABLE DENDRITIC SNOW CRYSTAL GROWTH TEMPS. FOW NOW...WILL PAINT NEAR ADVY LEVEL SNOW ACCUMULATIONS ACROSS THE KEWEENAW. TROF HANGS UP OVER ERN LAKE SUPERIOR SO WSW WINDS WILL KEEP LES OFFSHORE OF THE ERN FCST AREA. WINDS BACK TOWARD THE SW OVER NRN LAKE MICHIGAN...BUT ALL THE MODELS SUGGEST WINDS WILL HAVE JUST ENOUGH WRLY COMPONENT TO KEEP LES E OF FCST AREA. OTHERWISE...MIGHT SEEM PATCHY -SN/FLURRIES WITH PASSAGE OF SHORTWAVE. EXPECT A RELATIVELY QUIET DAY THU UNDER WEAK SHORTWAVE RIDGING DOWNSTREAM OF SHORTWAVE TROF DROPPING INTO THE NRN PLAINS. THIS WILL BE THE SYSTEM INITIATING THE ARCTIC BLAST FOR THE END OF THE WEEK. WINDS WILL MAINTAIN ENOUGH OF WRLY COMPONENT THU OVER WRN LAKE SUPERIOR TO KEEP LES IN THE PICTURE FOR THE KEWEENAW. HOWEVER... DRYING EVIDENT IN GFS/NAM FCST SOUNDINGS AND INVERSION DROPPING TO 3-4KFT WILL KEEP LES ON THE LIGHT SIDE...PERHAPS NOT MUCH MORE THAN FLURRIES BY AFTN. SHORTWAVE WILL SWING THRU THE WRN GREAT LAKES FRI WITH SFC LOW PRES ORGANIZING AND THEN DEEPENING MOST LIKELY OVER ERN LAKE SUPERIOR DUE TO HEAT/MOISTURE FLUXES (850MB TEMPS WILL BE AROUND -16C FRI MORNING). GIVEN THE INSTABILITY OVER THE LAKE AND DEEP LAYER FORCING WITH SHORTWAVE STRENGTHENING WITH TIME PER NAM/GFS 850-500MB QVECTOR CONVERGENCE...SFC LOW AND THE WIND FIELDS TO THE W AND N OF SFC LOW WILL PROBABLY BE STRONGER THAN WHAT ANY OF THE 00Z MODELS SHOW. SHOULD BE A GOOD SETUP FOR A PERIOD OF HVY SNOW NEAR LAKE SUPERIOR AS WINDS SWING SHARPLY AND STRONGLY TO THE NW. WILL LIKELY BE A HEADLINE EVENT FOR MOST IF NOT ALL OF THE COUNTIES BORDERING LAKE SUPERIOR. TEMPS WILL RISE LITTLE OVER THE W WITH EARLY FROPA. OVER THE WEEKEND AND INTO EARLY NEXT WEEK...THE COLDEST AIR OF THE SEASON WILL SETTLE OVER THE AREA. ACTUALLY...THE COLD WILL RIVAL SOME OF THE COLDEST OUTBREAKS DURING THE LAST 10 YEARS. MEDIUM RANGE MODELS FOR OVER A WEEK HAVE BEEN INDICATING THIS SCENARIO...AND IT IS NOW ONLY THE EXACT DETAILS OF HOW COLD IT WILL GET THAT REMAIN IN QUESTION. CONSENSUS OF THE LAST FEW DAYS OF ECWMF/GFS RUNS IS THAT 850MB TEMPS WILL BOTTOM OUT IN THE -28 TO -32C RANGE LATE IN THE WEEKEND. NOGAPS AND SEVERAL RECENT LOCAL HEMISPHERIC WRF-ARW RUNS HAVE INDICATED 850MB TEMPS OF -34C TO AS LOW AS -38C. IT IS VERY RARE TO SEE AIR THAT COLD HERE...SO THOSE SOLUTIONS ARE VIEWED AS OUTLIER SOLUTIONS FOR NOW. IN ANYCASE...SAT THRU TUE WILL BE AN EXTREMELY COLD PERIOD...ESPECIALLY SAT/SUN/MON. IT IS CERTAINLY POSSIBLE THAT SOME LOCATIONS OVER THE W HALF OF UPPER MI AWAY FROM LAKE SUPERIOR INFLUENCE WILL SEE TEMPS REMAIN BLO ZERO FROM FRI NIGHT UNTIL TUE AFTN. MIN TEMPS WILL DEPEND ON CLOUD COVER/WINDS...BUT -10F TO -20F SHOULD BE THE RULE AWAY FROM LAKE SUPERIOR INFLUENCE. IF SFC HIGH PRES RIDGE CAN SETTLE OVER THE AREA ONE NIGHT EARLY NEXT WEEK...MIN TEMPS IN THE USUAL WEST HALF COLD SPOTS WOULD EASILY PLUMMET BLO -30F. WINDS DON`T LOOK TOO STRONG THRU THE PERIOD...SO WIND CHILLS WON`T BE AS LOW AS COULD BE THE CASE. AS FOR LAKE EFFECT...GFS FCST SOUNDINGS ARE ACTUALLY FAIRLY MOIST WITH HIGH INVERSIONS 8KFT TO AS MUCH AS 15KFT. HOWEVER...AN OVERWHELMING NEGATIVE FOR SIGNIFICANT SNOW IS THE VERY COLD AIR WHICH WILL SEVERELY LIMIT SNOW CRYSTAL GROWTH AND THUS ACCUMULATIONS. ALTHOUGH ACCUMULATIONS ARE EXPECTED TO BE FAIRLY LIGHT EACH DAY...DURING SNOW SHOWERS THE AIR WILL BE THICK WITH SMALL SNOWFLAKES WHICH WILL BE EXTREMELY EFFECTIVE AT REDUCING VISIBILITY TO NEAR ZERO. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING UNTIL 1 PM TODAY MIZ003. LAKE EFFECT SNOW WARNING UNTIL 1 PM TODAY MIZ006-007. LAKE EFFECT SNOW ADVISORY UNTIL 1 PM TODAY MIZ001. && $$ AJ (UPDATE) ROLFSON (PREV DISCUSSION) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 254 PM MST WED JAN 31 2007 .SHORT TERM... (TONIGHT AND THURSDAY) MAIN FORECAST CONCERN REMAIN SNOW AMOUNTS TONIGHT. CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING BROAD UPPER TROUGH ACROSS THE UPPER GREAT LAKES BACK THROUGH THE ROCKIES WITH TROUGH AXIS MOVING ACROSS NORTHWEST COLORADO ATTM. WATER VAPOR IMAGERY ALSO INDICATING YET ANOTHER SYSTEM DIVING NORTH OUT OF CENTRAL CANADA AND INTO THE NORTHERN TIER STATES ATTM. AT THE SFC...COLD FRONT WHICH BLASTED ACROSS EASTERN COLORADO EARLY THIS MORNING IS CURRENTLY BACKED UP ACROSS THE EASTERN MTS THROUGH EASTERN NEW MEXICO AND ACROSS WESTERN TEXAS PANHANDLE ATTM AS HIGH PRESSURE CONTINUES TO BUILD INTO THE SOUTHERN HIGH PLAINS. REGIONAL SATELLITE AND RADARS INDICATING CLOUD TOP COOLING AND WIDESPREAD ECHOES ACROSS WESTERN AND SOUTH CENTRAL COLORADO ATTM. FOR TONIGHT...UPPER TROUGH CONTINUES TO TRANSLATE ACROSS THE STATE WITH TROUGH AXIS MOVING ACROSS SOUTH CENTRAL COLORADO AROUND 06Z THU AND INTO SOUTHWEST KANSAS BY 12Z...AS NEXT CANADIAN SYSTEM CONTINUES TO MOVE INTO THE NORTHERN ROCKIES. MOISTURE AND LIFT ASSOCIATED WITH PASSING SYSTEM SHOULD CONTINUE TO MOVE ACROSS SOUTH CENTRAL COLORADO THIS EVENING AND INTO WESTERN KANSAS OVERNIGHT WITH ASSOCIATED PRECIPITATION DIMINISHING QUICKLY FROM WEST TO EAST WITH PASSAGE OF TROUGH AXIS...SAVE THE CENTRAL MTS WITH CONTINUED OROGRAPHIC FLOWS. HAVE KEPT CURRENT HIGHLIGHTS IN PLACE ACROSS THE SW AND CENTRAL MTS WITH ANOTHER 1 TO 4 INCHES EXPECTED THROUGH THE EVENING. SPOTTER REPORTS INDICATING GENERALLY UNDER 2 INCHES HAS FALLEN ACROSS THE EASTERN MTS ATTM...THOUGH WITH EAST TO NORTHEAST LOW LEVEL UPSLOPE CONTINUING TO DEVELOP...WILL KEPT CURRENT HIGHLIGHTS ACROSS THE SOUTHEASTERN MTS AS WELL...WITH ADDITIONAL ACCUMS BETWEEN 2 AND 6 INCHES EXPECTED...WITH HIGHEST AMOUNTS ACROSS THE SOUTHERN SANGRE DE CRISTO MTS. SNOW HAS BEEN RATHER SPOTTY ACROSS THE I-25 CORRIDOR THUS FAR...BUT EXPECT THAT TO INCREASE AS TROUGH MOVES ACROSS THE AREA WITH AN ADDITIONAL 1 TO 3 INCHES POSSIBLE...ESPECIALLY WESTERN AREAS CLOSER TO THE HIGHER TERRAIN. NOT EXPECTING MUCH IN THE WAY OF ACCUMULATING PRECIP ACROSS THE FAR EASTERN PLAINS...BUT CANT RULE OUT A FEW SNOW SHOWERS OVERNIGHT AHEAD OF PASSING SYSTEM. WITH COLD AIR IN PLACE...OVERNIGHT LOWS TO REMAIN BELOW SEASONAL AVERAGES...AND HAVE GONE AOB COOLEST GUIDANCE...ESPECIALLY THE SAN LUIS AND LOWER ARKANSAS VALLEYS WITH PARTIAL CLEARING EXPECTED BY MORNING. ON THURSDAY...NORTHWEST FLOW ALOFT INCREASES ACROSS THE STATE AS NEXT SYSTEM CONTINUES TO DIVE INTO THE NORTHERN ROCKIES WITH ASSOCIATED FRONTAL BOUNDARY PROGGED TO MOVE ACROSS NORTHEAST COLORADO BY LATE AFTERNOON. HAVE FOLLOWED CLOSER TO GFS SOLUTION WITH FASTER MOVEMENT OF FRONTAL BOUNDARY...AND HAVE INTRODUCED CHANCE POPS ACROSS THE EASTERN MTS AND ALONG THE PALMER DVD FOR THE AFTERNOON. WITH MOISTURE AND LIFT AND OROGRAPHIC FLOW INCREASING ACROSS THE CENTRAL MTS...HAVE GONE WITH LIKELY POPS WITH 1 TO 3 INCHES POSSIBLE THROUGH THE AFTERNOON. -MW .LONG TERM... (THU NIGHT THROUGH WED) ...FLUFFY SNOW ANTICIPATED FOR THU NIGHT INTO FRI... ...PREPARE NOW FOR EXTREMELY COLD TEMPERATURES FRI-WEEKEND... ...DANGEROUS WIND CHILL VALUES POSSIBLE FRI NIGHT-SAT... THU NIGHT AND FRI...NEXT CANADIAN WEATHER SYSTEM WILL BE TAKING AIM ON THE CENTRAL ROCKIES AND THIS IS STRONGEST ONE OF THE ARCTIC SYSTEM INTRUSIONS. SIGNIFICANT COLD FRONT SHOULD BE BLASTING THROUGH CO THU NIGHT AND COULD BE FASTER. A LITTLE BETTER AND DEEPER SYNOPTIC SCALE ASCENT IMPLIED GIVEN THE DYNAMICS. H5-H3 DIV-Q IMPLIED UPWARD VERTICAL MOTION JUXTAPOSED WITH H8-H7 AND H7-H6 IMPLIED UPWARD VERTICAL MOTION PER 2-D PETTERSON ANALYSES. BOTH 12KM WRF AND GFS HAVE THIS SCENARIO FOR THU NIGHT INTO FRI MORNING...SO CONFIDENCE IS SOMEWHAT HIGH OF PRECIPITATION AND ACCUMULATING SNOWFALL. HAVE INCREASED POPS TO HIGH "LIKELYS" FOR THU NIGHT INTO FRI MORNING FOR THE CENTRAL AND EASTERN MOUNTAINS INCLUDING THE I-25 CORRIDOR. GIVEN THE THERMAL STRUCTURE ALONG THE FRONT...EXCELLENT DENDRITIC SNOW GROWTH WILL BE LIKELY IN THE MOIST LAYER RESULTING IN 20-1 TO 40-1 SNOW RATIOS PRODUCING FLUFFY SNOW THAT CAN ADD UP QUICKLY IN LOW WATER CONTENT SNOWFALL. MIGHT NEED SOME ADVISORIES FOR OUR EASTERN CO MOUNTAINS AND I-25 CORRIDOR AS THE EVENT NEARS. PRECIPITATION CHANCES SHOULD BE DIMINISHING BY FRI AFTERNOON. TEMPERATURES WILL LIKELY BE STEADY OR SLOWLY FALLING FRI...BUT IF THE PRECIPITATION STOPS DURING THE THE AFTERNOON...THEN THERE COULD BE A COUPLE OF DEGREES RECOVERY. CURRENT TEMPERATURES FORECAST LOOKS ON TARGET AND ONLY MINOR SPATIAL CONSISTENCY ISSUES WERE TAKEN CARE OF. FRI NIGHT AND SAT...12KM WRF AND GFS KIND OF DIVERGE IN TERMS OF THE AMOUNT OF MIDLEVEL TEMPERATURES WARMING THAT OCCURS. THE GFS IS SLIGHTLY WARMER IN THE MIDLEVEL FRI NIGHT THROUGH SAT...WHILE THE WRF HAS H7 TEMPERATURES -18C TO -26C EVEN DURING THE DAYTIME PERIOD SAT. IT SHOULD BE MUCH BELOW AVERAGE CHILLY TEMPERATURES...EITHER EXTREMELY COLD OR VERY COLD. SUB-ZERO LOW TEMPERATURES WILL BE HIGHLY PROBABLE ACROSS MUCH SOUTHERN CO LOCATIONS FRI NIGHT AND STRUGGLING TO WARM SAT...ESPECIALLY IN TRAPPED VALLEYS AND OVER DENSE SNOW-PACK. A BIG FORECAST CONCERN WILL BE DANGEROUS WIND CHILLS FRI NIGHT INTO SAT. COULD REACH WARNING VALUES IN THE MOUNTAINS(E.G. -35F OR LOWER) AND ADVISORY TO MAYBE WARNING VALUES AT THE LOWER ELEVATIONS. MOST AREAS WILL SEE WIND CHILL VALUES OF -15F TO -35F LATE FRI NIGHT AND SAT MORNING. WIND CHILL HEADLINES MAY BE NEEDED AS THE EVENT GETS CLOSER AND THE HAZARDOUS WEATHER OUTLOOK HAS THIS HANDLED WELL RIGHT NOW. ANY PRECIPITATION POTENTIAL WOULD LIKELY BY AROUND THE CONTINENTAL DIVIDE GIVEN THE WEST-NORTHWEST FLOW ALOFT. SUN THROUGH WED...NORTHWEST FLOW DEVELOPS SUN AND INTO EARLY NEXT WEEK AS THE EXTREMELY COLD TROUGH MIGRATES EASTWARD. MIDLEVEL WARMING STARTS SUN AND THE BIGGEST CHALLENGE WILL BE WHEN AND IF THE LOW LEVEL ARCTIC AIR MASS RECEDES FROM EASTERN CO AND GETS "MIXED OUT" FROM THE HIGH MOUNTAIN VALLEYS. HAVE TRENDED TOWARDS A MODERATING TEMPERATURE TREND...BUT HELD TEMPERATURES BACK A LITTLE IN HIGH VALLEYS AND DENSE SNOW-PACK AREAS LIKE KLAA. HPC GUIDANCE HAS A SIGNIFICANT WARM-UP FORECAST FOR TUE AND WED. THIS MAY BE VALID AS A PATTERN CHANGE TO WESTERLY FLOW GIVEN MANY OF THE ENSEMBLE MEMBERS. THE CHALLENGE WILL CONTINUE TO BE THE WARM-UP OVER DENSE SNOW-PACK...WHERE HPC AND MOS GUIDANCE HAVE BEEN TOO WARM PER GRIDDED VERIFICATION DATA. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... SNOW ADVISORY UNTIL 11 PM MST THIS EVENING FOR COZ058>060-066- 068-072>075-079-080. && $$ 23/17 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 324 PM EST WED JAN 31 2007 .SHORT TERM... (TONIGHT THROUGH THURSDAY NIGHT)... ...SNOW ADVISORY ACROSS SOUTHERN KY AND SOUTHERN BLUEGRASS... SHORT-TERM FORECAST REVOLVES AROUND SOUTHERN STREAM SYSTEMS AND SNOW ACCUMULATION CHANCES WITH EACH. TONIGHT-MIDDAY THURS... HIGH PRESSURE OVERHEAD WILL MOVE OFF TO THE EAST TONIGHT...AS AN INVERTED TROUGH OVER THE GULF MOVES FROM TEXAS TOWARD THE CAROLINAS. MOISTURE IS NOT TOO IMPRESSIVE WITH THIS SYSTEM...HOWEVER THE DYNAMICS ARE STRONG. SOUTHERN JET OF ROUGHLY 150 KTS OR SO WILL BE OVERHEAD...WITH THE CWA UNDER THE LEFT-EXIT REGION AFTER MIDNIGHT. AMPLE LIFT WILL THUS HELP SNOW DEVELOP AFTER MIDNIGHT TOWARD MORNING. AREA SOUNDINGS INDICATE THE BEST CHANCE OF SNOW WILL BE BETWEEN 10-17Z. SOME HEAVIER SNOW MAY MIX IN AT TIMES GIVEN UPSTREAM REPORTS AND PROGGED -EPV ALOFT CO-LOCATED WITH MAX OMEGAS. BUT GIVEN THE LACK OF MOISTURE AND SPEED OF SYSTEM...WILL NOT GET CARRIED AWAY WITH SNOW AMOUNTS. THUS...WILL ISSUE A SNOW ADVSY FROM 1-2 INCHES POSSIBLE MAINLY SE OF A LINE FROM MORGANTOWN TO LEBANON. MAY BE A BIT TOO FAR NORTH WITH THE ADVY GIVEN THE NAM 18Z RUN...BUT 12Z GFS/NAM AND HPC INDICATE FAR SRN KY COULD GET THESE ACCUMULATING SNOWS. THE BIGGER PROBLEM WILL BE TIMING NOT THE ACTUAL ACCUMS. GIVEN TIME OF DAY (NEAR MORNING COMMUTE TIME) FELT IT WAS WORTH BUMPING UP THE SPS TO AN ADVSY. WILL KEEP THE HIGHER SNOW AMOUNTS ACROSS THE FAR SERN CWA. ELSEWHERE...WILL CONTINUE SPS FOR AROUND AN INCH OF ACCUMULATION. FEEL THAT THE THREAT IS MINIMIZED ACROSS CENTRAL KY...HOWEVER A BETTER CHANCE MAY EXIST NEAR THE OHIO RIVER WITH THE DEFORMATION ZONE DEVELOPING FROM KC TO WICHITA. THIS SHOULD ALIGN SOMEWHERE ACROSS OUR NRN CWA...POSSIBLY NEAR THE KY/IN BORDER. SNOWFALL AMOUNTS WITHIN THE SPS AREA WILL BE HIGHER IN THE DEFORMATION ZONE...BUT IT IS STILL EXPECTED TO BE LIGHT SNOW ONLY. MAIN PRECIP WILL END BY MIDDAY (ADVY ENDS AT 18Z)...THOUGH LOW CLOUDS MAY CONTINUE THROUGH THE AFTERNOON. WITH THIS...EVEN A FEW LIGHT SHOWERS/FLURRIES MAY CONTINUE INTO THE AFTERNOON HOURS. SFC TEMPS MAY INCREASE ENOUGH ACROSS THE SOUTH WHERE A CHANGEOVER TO LIGHT RAIN/DRIZZLE MAY OCCUR. HAVE A RAIN/SNOW MIX ACROSS THE SOUTH FOR NOW. MIDDAY THURS-OVERNIGHT THURS... SECOND WAVE IN SOUTHERN STREAM WILL QUICKLY MOVE TOWARD THE EAST COAST RIGHT ON THE HEELS OF THE FIRST SYSTEM. THIS SYSTEM IS MORE OF A CLOSED SFC LOW AS OPPOSED TO A SFC TROUGH...AND IS COMBINED WITH EVEN STRONGER DYNAMICS ALOFT. HOWEVER MOISTURE IS EVEN MORE LACKING...BUT THE DYNAMICS ARE THERE FOR YET ANOTHER POSSIBLE ADVSY SITUATION THRS NIGHT-FRI MORN. WILL LOOK MORE AT IT TONIGHT AND TOMORROW MORNING...BUT WILL HIT IT HARD IN THE HWO. THIS LATTER SYSTEM WOULD BE MORE OF A CWA-WIDE EVENT TOO. WILL CONTINUE WITH ONE-INCH ACCUMS FOR NOW. AS FAR AS TEMPS GO THROUGH THE PERIOD...WILL ONLY DROP ABOUT 5 DEGREES TONIGHT BEFORE CLOUDS INCREASE OVERNIGHT AND KEEP OUR TEMPS STEADY. TOMORROW...WILL LIKELY HEAT UP...ESPECIALLY IN THE AFTERNOON. HOWEVER WILL UNDERCUT RUC13/GFS AS I FEEL THESE ARE RUNNING A BIT TOO HIGH. LOW TO MID 30S LOOK LIKELY FOR HIGHS THURS. AL .LONG TERM (FRI THRU WED)... FRI THRU SAT NGT... SHRTWV TROF WILL BE DROPPING DOWN INTO THE UPR MS VLY/WRN GREAT LAKES AT THE START OF THE PERIOD WITH MORE ENERGY ROUNDING THE BASE OF THE UPR LEVEL BROAD TROF TOWARD THE LOWER MS VLY. THIS ELONGATED AXIS OF HIER VORTICITY BECOMES INCREASINGLY SHEARED AS IT MOVES THRU OUR FA FRI WITH AFOREMENTIONED SHRTWV MOVG WELL TO OUR NORTH...ACRS THE GREAT LAKES. AFTERWARD...WE REMAIN IN A BROAD TROF THRU THE END OF THE PERIOD WITH ANOTHER IMPLSE APPROACHING OUR FA SAT NIGHT. ASSOCIATED CDFNT WILL MOVE THRU FRI...WITH A RIDGE OF HI PRES IN ITS WAKE FOR FRI NIGHT AND MUCH OF SAT. WILL CONTINUE CHC POPS FOR LIGHT SNOW PRECEDING FRONT...MAINLY IN THE FIRST HALF OF THE DAY. A REINFORCING SHOT OF COLD AIR...ASSOCIATED WITH AFOREMENTIONED IMPULSE...WILL LIKELY MOVE THRU OUR FA SAT NIGHT. WILL DOWNPLAY THE NAM/WRF DEEPER MOISTURE PRECEDING AND WITH FRONT AND CONT A PARTLY CLOUDY FCST...CLOSER TO THE GFS. 11 SUN THRU WED... VERY COLD AND MAINLY DRY THRU THIS PERIOD. BROAD UPR LEVEL TROF WILL RESIDE ACRS THE OH VLY THRU LATE MON WITH AXIS SHIFTING INTO NEW ENGLAND TUE AND OFF THE NEW ENGLAND COAST WED. AFTER AXIS PASSAGE MON...OUR REGION WILL BE IN COLD NW FLO THRU THE END OF THE PERIOD. 00Z MEDIUM RANGE MODELS AND 12Z GFS ARE SIMILAR WITH SHOWING A FAST MOVG CLIPPER SYS/WEAK SFC LO MOVING INTO THE LOWER OH VLY SUN NGT AND EXITING MON MORNING. THIS APPEARS TO BE OUR BEST CHC FOR A MEASURABLE SNOW DURING THIS PERIOD WITH POSSIBLY A 1 TO 3 INCH DRY FLUFFY SNOW ACRS OUR FORECAST AREA(FA)...MOSTLY OVER OUR NRN/ERN FA. TEMPS WILL BE UNSEASONALLY COLD...ESPECIALLY AFTER CLIPPER PASSAGE MON WITH SINGLE DIGIT READINGS MON AND TUE NGT AS ARCTIC HI PRES BUILDS INTO AND OVER THE LOWER OH VLY. AFTER POPULATING WITH HPC GRIDS FOR TUE AND WED...WILL MAKE THE FOLLOWING CHGS TO TEMP GRIDS. WILL RAISE SUN NGT MINS CONSIDERABLY TO ACCOUNT FOR INCREASING CLOUDS/A BRIEF PERIOD OF WARM ADVECTION AHEAD OF CLIPPER. WILL RAISE MAXS MON A FEW DEGREES CLOSER TO ENSEMBLE MEANS AND HPC AND TO AGREE BETTER WITH OUR NEIGHBORS. IF WE GET AN INCH OR TWO OF SNOW COVER BEFORE THIS PERIOD AND ON SUN NGT AS WELL...THESE TEMPS WILL NEED TO BE ADJUSTED DOWN...IN OTHER WORDS...BELOW ZERO FOR MINS BEGINNING MON NGT. DK && .AVIATION (18Z TAFS)... VFR CONDITIONS WILL CONTINUE FOR THE SDF...LEX AND BWG TAF SITES THROUGH THE FIRST SIX HOURS OF THIS TAF FORECAST. HIGH PRESSURE OVERHEAD WILL KEEP MOSTLY SUNNY CONDITIONS WITH LIGHT VARIABLE TO SOUTH WINDS...5 TO 10 MPH. MID-LEVEL DECK WILL FILTER IN FROM THE WEST FROM 21-00Z THIS EVENING. CIGS SHOULD STAY VFR UNTIL 06Z FOR BWG...AND BY 10Z AND 12Z FOR SDF AND LEX RESPECTIVELY...WHERE LIGHT SNOW MAY REDUCE VISBYS DOWN TO ONE MILE OR SO AT TIMES. ONSET OF -SN WILL BE LIGHT DUE TO LOWER LEVELS NOT BEING FULLY SATURATED. MAY CARRY A TEMPO FOR HEAVIER SNOW FOR THE BWG TAF ROUGHLY FROM 10-14Z. ONCE SNOW BEGINS...MAY TREND TOWARD LOWER END MVFR CIGS AND IFR VISBYS WITH THE HEAVIER SNOW SOMETIME BETWEEN 12-18Z FOR ALL TAF SITES. AL && .LMK WATCHES/WARNINGS/ADVISORIES... KY...SNOW ADVISORY FROM 5 AM EST /4 AM CST/ TO 1 PM EST /12 PM CST/ THURSDAY FOR KYZ062>066-070>078-081-082. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 434 PM EST WED JAN 31 2007 .SHORT TERM...TONIGHT AND THURSDAY OVERNIGHT LOWS LIKELY TO OCCUR SHORTLY AFTER SUNSET...ESPECIALLY ACROSS THE SOUTHERN PORTIONS OF THE AREA WHERE CURRENT TEMPS REMAIN IN THE TEENS...15 AT ADRIAN. THUS...LOWEST OVERNIGHT LOWS ARE EXPECTED IN THAT AREA. THEN TEMPS ARE EXPECTED TO LEVEL OFF AND POSSIBLY CLIMB A LITTLE OVERNIGHT UNDER A WEAK WARM AIR ADVECTION REGIME. THE POTENTIAL FOR SCATTERED LIGHT SNOW SHOWERS ARRIVES AFTER MIDNIGHT AND WILL EXIST THROUGH THURSDAY. LIMITED MOISTURE AND A WEAKENING SYSTEM WILL KEEP SNOW SHOWERS ON THE LIGHT SIDE WITH LITTLE TO NO ACCUMULATION EXPECTED. THE SAGINAW VALLEY STANDS TO SEE THE BEST ACTIVITY AS THAT IS THE FAVORED AREA FOR LAKE LAKE ENHANCED SNOW SHOWERS WITHIN SOUTHWESTERLY FLOW REGIME. LATEST RUC ANALYSIS/SATELLITE DATA SUPPORTS THE MODELS CONSISTENT FORECAST OF THE SHORT WAVE SHEARING OUT WITHIN CONFLUENT FLOW ALOFT OVER THE GREAT LAKES EARLY THURSDAY MORNING. UPPER DIVERGENCE...WITHIN RIGHT ENTRANCE REGION OF DEPARTING JET STREAK... WILL BE SUPPORTIVE OF EXTRA LIFT OVERNIGHT...MAINLY ACROSS THE NORTH HALF OF THE CWA. MODEL SOUNDINGS INDICATE THAT THE VERY DRY 900 TO 700 MB COLUMN OF AIR WILL THEN MOISTEN UP CONSIDERABLY DURING THE EARLY MORNING HOURS. BUT WITH VERY LITTLE INSTABILITY AND LACK OF LOW LEVEL SUPPORT...ANY SNOW SHOWERS SHOULD REMAIN ON THE TAME SIDE. BY THE TIME BETTER LOW LEVEL SUPPORT ARRIVES ON THURSDAY...THE MID AND UPPER LEVEL MOISTURE WILL BEGIN TO STRIP AWAY AS THE UPPER SUPPORT BECOMES SHEARED OUT. HOWEVER WITH INVERSION HEIGHTS AROUND 800 MB ON THURSDAY NORTH OF DETROIT...LINGERING SNOW SHOWERS CANNOT BE RULED OUT. && .LONG TERM...THE PLAINS WAVE WILL HAVE SHEARED TO OUR EAST BY THURSDAY NIGHT LEAVING ONLY A CHANCE OF LIGHT SNOW SHOWERS OR FLURRIES UNTIL THE NEXT SYSTEM ARRIVES FROM CENTRAL CANADA ON FRIDAY. THIS FEATURE LOOKS TO BE HANDLED WELL JUDGING FROM SATELLITE IMAGERY TODAY BUT IT IS HARD TO GET EXCITED ABOUT THE PROSPECTS FOR SNOW AS IT MOVES THROUGH OUR AREA FRIDAY AFTERNOON. MID LEVEL MOISTURE WILL BE AT A PREMIUM AS THE WAVE WILL BE CUT OFF FROM BOTH GULF AND PACIFIC MOISTURE SOURCES. HOWEVER, A BOOST FROM LAKE MICHIGAN LOOKS REASONABLE AS THE COLD FRONT MOVES THROUGH LOWER MICHIGAN FRIDAY AFTERNOON AND EVENING. THIS IS WORTH CHANCE/SCATTERED POPS FOR SNOW SHOWERS. OUR FIRST SURGE OF ARCTIC AIR WILL ARRIVE BEHIND THIS SYSTEM FRIDAY NIGHT. THE 12Z MODELS ALL SHOW 850 MB TEMPS DROPPING TO AROUND -20C BY SUNRISE SATURDAY MORNING. A SW COMPONENT TO THE WIND WILL INITIALLY HELP WITH SINGLE DIGIT LOW TEMPERATURES, DESPITE SOME CLOUD COVER, AS COLDER SURFACE AIR FLOWS AROUND THE SOUTH END OF LAKE MICHIGAN AND INTO OUR AREA. HOWEVER, THIS SAME SW FLOW WILL STRENGTHEN AND ADVECT SOMEWHAT WARMER AIR INTO THE REGION AS THE SURFACE HIGH DRIFTS EAST AND AHEAD OF THE NEXT WAVE OF LOW PRESSURE SCHEDULED TO ARRIVE ON SATURDAY. IN THIS REGARD, GUIDANCE TEMPERATURES CALLING FOR HIGHS IN THE TEENS LOOK OK BUT THESE READINGS WILL BE ACCOMPANIED BY A 10 TO 20 MPH WIND AND WIND CHILLS NEAR 10 BELOW ZERO. THERE ARE SOME TIMING DIFFERENCES IN THE 12Z MODELS ON THE HANDLING OF THE SATURDAY WAVE. PREFER THE FASTER SOLUTIONS, OF WHICH THE GFS IS ONE, AS RENEWED HEIGHT FALLS GET UNDERWAY IN CENTRAL CANADA AND ANCHOR THE POLAR VORTEX OVER NORTHERN ONTARIO. THIS SYSTEM WILL BRING OUR BEST CHANCE OF SNOW DURING THE WEEKEND AND REPLENISH THE ARCTIC AIR MASS SATURDAY NIGHT AND SUNDAY. THIS WILL BE THE MOST BRUTAL PORTION OF THE COLD OUTBREAK WHEN FACTORING IN BOTH TEMPERATURE AND WIND TAKING WIND CHILL TO AROUND -20F. THE GFS FORECASTS 850 MB TEMPS TO DROP DOWN NEAR -28C WHICH CORRESPONDS TO DAYTIME TEMPERATURES NO BETTER THAN THE SINGLE DIGITS ON SUNDAY. IN FACT, DAYTIME TEMPERATURES TODAY IN REGIONS OF NORTHERN CANADA SHOW A FEW READINGS STILL BELOW ZERO WITH SIMILAR 850 MB TEMPERATURES. IN ADDITION, THERE WILL LIKELY BE CONSIDERABLY MORE OF A SURFACE PRESSURE TROUGH IN THE LEE OF LAKE MICHIGAN WHICH WILL DIRECT A SW FLOW OF LESS MODIFIED AIR INTO SE MICHIGAN. THE LAST TIME METRO DETROIT HAD AT LEAST TWO CONSECUTIVE DAYS OF SINGLE DIGIT HIGH TEMPERATURES WAS IN JANUARY 1994. VERY LITTLE TEMPERATURE MODERATION IS EXPECTED ON MONDAY AS THE CORE OF THE POLAR VORTEX MOVES OVER THE GREAT LAKES. THE GLOBAL MODELS DO SHOW THE VORTEX MOVING EAST BY TUESDAY BUT DEEP NW FLOW WILL CONTINUE THE SUPPLY OF ARCTIC AIR THROUGH THE MIDDLE OF NEXT WEEK. SOME MODERATION IS POSSIBLE ON TUESDAY AND WEDNESDAY AS THE WIND BACKS TOWARD THE WEST AND NORTHWEST, PREVENTING THE LESS MODIFIED AIR FROM MOVING INTO THE REGION. && .AVIATION...ISSUED AT 104 PM EST SOUTHWEST FLOW AND WEAK WARM AIR ADVECTION WILL CONTINUE TO SUPPORT MID CLOUDS TODAY. MARINE CLOUDS TO CONTINUE THIS AFTERNOON AT THE FNT AND MBS TERMINALS...WITH MVFR CEILINGS EXPECTED PERIODICALLY. MVFR CEILINGS TO MOVE IN AGAIN AND BECOME MORE WIDESPREAD AFTER MIDNIGHT...IN ASSOCIATION WITH THE APPROACH OF A WEAK CLIPPER SYSTEM. MVFR CEILINGS ARE THEN EXPECTED TO REMAIN IN PLACE THROUGH THIS TAF PERIOD. THERE WILL BE SCATTERED LIGHT SNOW SHOWERS AROUND ON THURSDAY. SOUTHWESTERLY FLOW TO PROVIDE FNT AND MBS WITH AN OPPORTUNITY FOR SOME LAKE ENHANCED SNOW SHOWERS...THUS THE REASONING FOR A PERIOD OF MVFR VISIBILITIES IN THAT AREA. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY...LHZ421...NEARSHORE WATERS FROM PORT AUSTIN THURSDAY. SMALL CRAFT ADVISORY FOR WINDS...LHZ422 UNTIL 10 AM THURSDAY. LAKE ST CLAIR...SMALL CRAFT ADVISORY FOR WINDS...LCZ460 UNTIL 10 AM THURSDAY. MI WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY FOR WINDS...UNTIL 10 AM THURSDAY. && $$ SHORT TERM...JDS LONG TERM....BT AVIATION...JDS YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 330 PM EST WED JAN 31 2007 ...SEVERAL DAYS OF VERY COLD AIR EXPECTED THIS WEEKEND INTO NEXT WEEK... .SYNOPSIS... 20Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED OVERALL UPPER TROUGHING COVERING MUCH OF NORTH AMERICA...EXCEPT ALONG THE WEST COAST INTO ALASKA WHERE A VERY AMPLIFIED RIDGE EXISTS. FAIRBANKS 850MB TEMP WAS 10C! WITHIN THE UPPER TROUGH...THERE ARE A FEW FEATURES OF INTEREST. THE FIRST IS A SHRTWV TROUGH OVER WESTERN MINNESOTA. DPVA/ISENTROPIC LIFT AHEAD OF THE TROUGH AND A LITTLE MORE MOISTURE HAS ALLOWED FOR THE DEVELOPMENT OF AN AREA OF LIGHT SNOW ON THE MINNEAPOLIS RADAR ACROSS THE MINNEAPOLIS AREA INTO SW WISCONSIN. HOWEVER...THE NORTH END OF THIS REFLECTIVITY SHIELD IS MAINLY VIRGA...DUE TO DRY LOW LEVEL AIR AS NOTED BY THE 12Z MPX SOUNDING AND SURFACE DEWPOINT DEPRESSIONS OF 10-20F. THIS DRY LOW LEVEL AIR...COMBINED WITH A SOUTHERLY FLOW AHEAD OF A 1007MB LOW WEST OF DULUTH...HAS HELPED PUSH THE LAKE EFFECT CONVERGENT BAND AFFECTING THE KEWEENAW BACK OUT OVER THE NORTH CENTRAL PART OF LAKE SUPERIOR. THE RESULT IS NOW ONLY A FEW MID/HIGH CLOUDS ACROSS THE CWA. AS FAR AS AMOUNTS GO REGARDING THE EXPIRED HEADLINES... PLACES ACROSS THE KEWEENAW ENDING UP WITH 4 TO 6 INCHES WHILE THOSE BETWEEN THE PICTURED ROCKS NATIONAL LAKESHORE AND TAHQUAMENON FALLS ENDED UP WITH 4 TO 7 INCHES. ACROSS THE LUCE COUNTY LINE IN PARADISE...HOWEVER...SPOTTERS HAVE REPORTED 10 TO 15 INCHES. THE SECOND FEATURE OF INTEREST...WHICH IS EXPECTED TO BRING THE COLD AIR ALONG WITH A PERIOD OF HEAVY LES TO WESTERN UPPER MICHIGAN...IS A STRONGER SHRTWV LOCATED OVER NORTHERN SASKATCHEWAN. BEHIND THIS SHRTWV...850MB TEMPS ON 12Z RAOBS WERE OBSERVED NEAR -30C. THE ACTUAL ARCTIC FRONTAL BOUNDARY CAN BE SEEN DROPPING THROUGH CENTRAL SASKATCHEWAN/MANITOBA...WITH FALLING TEMPERATURES BEHIND IT. && .SHORT TERM (TONIGHT AND THU)... TONIGHT...THE SHRTWV TROUGH OVER MINNESOTA IS PROGGED TO TRACK ACROSS MUCH OF UPPER MICHIGAN BY 06Z. ALL MODELS SEEM TO HAVE A GOOD HANDLE ON THE SNOW AFFECTING THE MINNEAPOLIS AREA AND BASICALLY HAVE MUCH OF IT GOING ACROSS WISCONSIN INTO LOWER MICHIGAN. IT APPEARS THE NORTHERN END MAY CLIP THE SOUTH CENTRAL COUNTIES...BUT AGAIN GIVEN THE LOW LEVEL DRY AIR SEEN ACROSS THE CWA AND ON THE 12Z GRB SOUNDING...DO NOT BELIEVE MUCH SNOWFALL WILL OCCUR. MEANWHILE...HIGH RESOLUTION MODELS DEPICT THAT THE SURFACE LOW ASSOCIATED WITH THE SHRTWV WILL REDEVELOP OVER CENTRAL LAKE SUPERIOR THIS EVENING...THEN MOVE TO EASTERN LAKE SUPERIOR AFTER MIDNIGHT. THE TROUGH EXTENDING SW FROM THE LOW WILL LIKELY CONTAIN SOME LES ALONG IT...PERHAPS EVEN THE CURRENT LES BAND THAT EXISTS ON THE WESTERN PORTION OF LAKE SUPERIOR. HOWEVER...MODELS DEPICT THE CONVERGENCE TO NOT BE AS STRONG AS EXPERIENCED LAST NIGHT ALONG THIS TROUGH...AND THUS THE QPF AMOUNTS ARE NOT NEARLY AS GREAT. HAVE SLOWED DOWN THE MOVEMENT OF THE LES INTO THE KEWEENAW BASED ON THE 13 KM RUC AND OUR HIGH RESOLUTION WRF RUN SINCE LOW LEVEL WINDS ARE PROGGED TO STAY SW UNTIL AFTER 06Z. THEREFORE SNOW AMOUNTS HAVE BEEN CUT BACK TONIGHT. THU...AS THE SHRTWV OVER NORTHERN SASKATCHEWAN PLOWS SOUTHWARD INTO THE NORTHERN PLAINS...RESULTING IN THE DEVELOPMENT OF A SURFACE LOW WHICH TRACKS TO DULUTH BY 00Z...SW FLOW REDEVELOPS AT THE SURFACE. HOWEVER...THE PRESSURE GRADIENT AHEAD OF THIS LOW IS NOT ALL THAT STRONG...WHICH MEANS THAT THE TROUGH THAT MOVES INTO THE KEWEENAW PENINSULA TONIGHT MAY GET HUNG UP OVER KEWEENAW COUNTY ON THU. THIS SCENARIO IS DEPICTED WELL IN HIGH RESOLUTION RUNS AND THE GFS. THEREFORE HAVE RAISED BOTH POPS AND SNOW AMOUNTS FOR THE KEWEENAW. KEPT AMOUNTS JUST BELOW ADVISORY CRITERIA...THOUGH...SINCE THE CONVERGENCE DOES NOT LOOK PARTICULARLY STRONG WITH ONLY A 90 DEGREE CHANGE IN DIRECTION ALONG THE BOUNDARY (COMPARED TO 180 DEGREES WITH THIS PAST EVENT). ELSEWHERE...DRY AIR FOLLOWING THE PASSAGE OF TONIGHTS SHRTWV LOOKS TO STAY IN PLACE...WHICH WILL HELP KEEP THE CWA DRY. ONLY MADE A FEW TWEAKS TO GOING FORECAST TEMPERATURES FOR TONIGHT AND THU BASED ON INCREASES/DECREASES IN CLOUD COVER AFFECTING RADIATION PROCESSES. NOTE THAT THESE READINGS WILL BE THE WARMEST THAT WEST AND CENTRAL UPPER MICHIGAN WILL SEE FOR AWHILE...PROBABLY THROUGH MUCH OF NEXT WEEK. .LONG TERM (THU NIGHT THROUGH NEXT WED)... FCST FOCUS FOR THU NGT/FRI CONCERNS TIMING/IMPACT OF FAIRLY SHARP SHRTWV FCST TO DROP FM SCNTRL CAN INTO THE UPR GRT LKS. MODEL TREND HAS BEEN TO SPEED UP THIS FEATURE AND ASSOCIATED SFC LO/ARCTIC FNT...SO FOLLOWED THE FASTER GFS/UKMET/CNDN MODELS FOR TIMING THE ARCTIC BNDRY PER NCEP PREFERENCE OVER THE SLOWER NAM. GFS SHOWS HEALTHY DPVA/H85-5 QVECTOR CNVGC/UPR DVGC/12HR H5 HGT FALLS NEAR 150M ASSOCIATED WITH SHRTWV MOVING INTO WI AT 12Z FRI AND THEN TO LK HURON BY 00Z SAT. ARCTIC FNT PROGGED TO REACH THE WRN ZNS BY 12Z FRI BEFORE PASSING ERY SHORTLY AFT 18Z. CONSIDERING THESE POTENT DYNAMICS AND DEEP MSTR DEPICTED ON THE GFS FCST SDNGS...WL MAINTAIN CATEGORICAL POPS AOA MOS FCST OVER THE W AS EARLY AS LATE THU NGT AND THEN ACRS ALL BUT THE SCNTRL ON FRI. SINCE THE SHRTWV IS PROGGED TO MOVE QUICKER WITH EARLIER ARRIVAL OF DPVA THU NGT AND THEN DNVA/H85-5 QVECTOR DVGC/LARGER SCALE SUBSIDENCE ON FRI...THE ONLY ADJUSTMENTS TO GOING FCST WX WL BE TO START THE HIER POPS EARLIER W-E THU NGT AND THEN END SYNOPTIC SN POPS EARLIER FRI AFTN. ARRIVAL OF ARCTIC AIR WL SPUR ONSET OF LES OFF LK SUP ON FRI...AND THERE APPEARS TO BE AT LEAST A 6-HR PD OF LK ENHANCEMENT OVER THE W BEFORE THE DYNAMICS EXIT FRI AFTN AND THE ACTIVITY EVOLVES TO PURE LES. SINCE FINER SCALE EXTENDED RUC13 GUIDANCE HINTS THE SFC LO MAY GET STUCK OVER ERN LK SUP WITH LATENT HEATING OFF THE WARM LK SUP WATERS...THINK THE MORE W LLVL WIND FIELD WL BE LESS FVRBL FOR LK ENHANCEMENT E OF THE HURON MTNS. ALTHOUGH THE ARRIVAL OF THE VERY LO H85 TEMPS (DOWN TO -25C AT IWD BY 00Z SAT) WL NEGATIVELY IMPACT SN GROWTH MICROPHYSICS...HAVE OPTED TO ISSUE WINTER STORM WATCH FOR LATE THU NGT THRU FRI FOR WRN COUNTIES BORDERING LK SUP AS WELL AS BARAGA COUNTY. WL GO WITH FALLING TEMPS OVER THE W ON FRI WITH ARRIVAL OF COLDER AIR. 12Z UKMET/GFS/ECMWF SHOW REINFORCING SHRTWV/DPVA/H85-5 QVECTOR CNVGC ARRIVING FRI NGT BEFORE DEPARTING ON SAT. ARRIVAL OF THIS SHRTWV/ DYNAMICS/DEEPER MSTR WL MAINTAIN HIER POPS FOR LK ENHANCED SN...BUT AIR IS SO COLD (H85 TEMPS FCST IN THE -24C TO -28C RANGE) LES OVERALL WL BE RELATIVELY LGT WITH POOR DENDRITIC SN GROWTH MICROPHYSICS. ONLY CONCERN WL BE BAND OF HEAVIER SHSN THAT COULD DVLP IN SHARP CNVGC BTWN MORE WLY LAND BREEZE FLOW OVER LAND AND SYNOPTIC SCALE NW WIND OVER LK SUP. LATER SHIFTS WL NEED TO EVALUATE THE NEED FOR ANY HEADLINES ONCE THE LOCATION OF THESE LLVL CNVGC AREAS CAN BE DETERMINED WITH MORE CONFIDENCE. WITH MORE WLY LAND BREEZE FLOW FRI NGT IN BACKED WINDS AHEAD OF APRCHG SHRTWV...PREFER LO END OF MOS GUIDANCE FOR LO TEMPS. GOING FCST HI TEMPS BLO ZERO OVER THE INTERIOR W SEEM RSNBL ON SAT GIVEN GFS/ECMWF FCST OF H85 TEMPS APRCHG -30C BY 00Z SUN IN WAKE OF SHRTWV. 00Z-12Z OPS MODELS/00Z GFS REFCST ENSEMBLE MEAN IN GOOD AGREEMENT SHOWING HI AMPLITUDE TROF IN ERN NAMERICA PERSISTING THIS WEEKEND INTO EARLY NEXT WEEK. GFS/ECMWF BOTH FCST H85 TEMP BOTTOMING OUT AS LO AS -28C TO -32C THIS WEEKEND BEFORE MODERATING MON-WED. 12Z TRENDS ARE SIMILAR...BUT LESS AGGRESSIVE AT RAISING THE H85 TEMPS THAN EARLIER RUNS. HOWEVER...GFS REFCST ENSEMBLE GUIDANCE HINT THAT CORE OF COLDEST AIR (H85 TEMPS AOA 2 STANDARD DEVIATIONS BLO NORMAL) WL NOT ARRIVE UNTIL MON/TUE FOLLOWING REINFORCING SHRTWV/SFC LO ON SUN/MON AS FCST BY 06Z GFS. THIS FCST WOULD SUG SGNFT MODERATION WL NOT ARRIVE UNTIL WED. WL GO WITH FCST TEMPS NR THE LO END OF MOS GUIDANCE FOR SAT-TUE. FCST SOMEWHAT HIER...MORE WDSPRD POPS ON SUN/SUN NGT TO ACCOUNT FOR PSBL REINFORCING SHRTWV. THE OPS MODELS DO SHOW A SOMEWHAT SHARPER PRES GRADIENT ON MON IN THE WAKE OF THIS SHRTWV AND IN ADVANCE OF ARCTIC HI PRES BLDG INTO THE NRN PLAINS...WHICH ALG WITH SAT (SHARPER PRES GRADIENT IN THE WAKE OF FRI LO) MIGHT END UP BEING THE DAYS WITH THE LOWEST WIND CHILLS AT LEAST CLOSE TO WRNG CRITERIA. OTRW...THE ONLY PCPN THRU THE PD WL BE LES MAINLY IN THE NW WIND SN BELTS LIMITED BY VERY COLD AIR THAT WL HAVE A NEGATIVE IMPACT ON SN GROWTH. BUT... SMALL SNFLAKE SIZE WL BE EFFECTIVE AT LIMITING VSBY. COORDINATED WITH DLH/GRB. && .MQT WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH THU NIGHT AND FRI MIZ001>004-009-084. && $$ AJ (SHORT TERM) KC (LONG TERM) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 335 PM CST WED JAN 31 2007 .DISCUSSION... BAND OF SNOW WITH FAIRLY SIG 850-700 MB THETA E ADVECTION AS DEPICTED BUT RUC HAS MOSTLY MOVED OFF INTO WI BUT REMAINS OF UPPER TROF MOVING ACROSS REST OF AREA THIS EVENING. FAIRLY SIG TROP LOWERING WITH THIS TROF..AND SIMILAR FORCING WILL BE MOVING INTO THE AREA BY THURSDAY AFTERNOON AND AGAIN FRIDAY AFTERNOON. WILL FOLLOW THE GFS ON TIMING AND IS VERY CLOSE TO ECMWF/UKMET. THE FIRST BLAST OF COLD AIR ARRIVES THURSDAY NIGHT...BUT THE STRONGER SURGE WILL BE FRIDAY NIGHT...WITH MORE DANGEROUS WIND CHILLS. THE UPPER JET WILL BE CLOSER TO THE AXIS OF STRONG LOW LEVEL COLD ADVECTION ON FRIDAY NIGHT. STILL MAY NEED AN ADVISORY IN WESTERN CWA ON THURSDAY NIGHT WITH THE COLD ADVECTION/WIND CHILLS/BLOWING SNOW POTENTIAL. THE LIKELY POPS STILL LOOK GOOD FOR THE TROUGH THURSDAY AFTERNOON/NIGHT BUT WILL SPEED UP THE ONSET A BIT. HAVE PAINTED IN A SMALL POP/ABOVE GUID/ FOR FRIDAY AFTERNOON/NIGHT BASED ON THE ABOVE MENTIONED FORCING AS WELL. THE ARCTIC AIR REMAINS ENTRENCHED FOR THE FIRST PART OF THE WEEK WITH MOSTLY CLEAR SKIES. HAVE DECREASED CLOUD COVER DRAMATICALLY IN THE SKY GRIDS WITH THE ARCTIC AIR IN PLACE. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JPR mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 406 PM CST WED JAN 31 2007 .DISCUSSION...SNOW THIS MORNING WAS MOST CONCENTRATED OVER NORTHERN OKLAHOMA...WITH 1 TO 2 INCHES. LIGHT SNOW AND SLEET ELSEWHERE WAS MORE INTERMITTENT...BUT THE FREEZING DRIZZLE WHICH FOLLOWED HAS GREATLY IMPACTED TRAVEL. THIS OCCURRED AS WESTERLY MID LEVEL WINDS AND SUBSIDENCE REMOVED MOISTURE FROM THE ICE CRYSTAL GROWTH ZONE...WHILE MOIST ISENTROPIC UPGLIDE CONTINUED AT LOWER LEVELS. THERE IS A DISTINCT BACK EDGE TO THE UPGLIDE PUSHING THROUGH CENTRAL AND SOUTHERN OKLAHOMA THIS AFTERNOON. A COLD FRONT WILL ALSO MOVE INTO WESTERN OKLAHOMA AND NORTH TEXAS THIS EVENING...SO LOW LEVEL DOWNGLIDE WILL BE THE RULE OVERNIGHT...HOPEFULLY PREVENTING ANY MORE FREEZING DRIZZLE. MEANWHILE...WE STILL APPEAR ON TRACK TO RECEIVE A SWATH OF SNOW LATE TONIGHT AND THURSDAY MORNING. ALTHOUGH NOT ESPECIALLY HEAVY...ACCUMULATIONS WILL OCCUR EITHER SIDE OF THE THURSDAY MORNING COMMUTE...AGAIN IMPACTING TRAVEL. WE ARE ALSO CONCERNED THAT FREEZING RAIN WILL IMPACT PARTS OF SOUTHERN OKLAHOMA AND WESTERN NORTH TEXAS LATER TONIGHT. ORIGINALLY...THIS WAS EXPECTED TO BE RAIN...BUT TEMPERATURES ARE A COUPLE OF DEGREES COOLER THAN EXPECTED THIS AFTERNOON. DEWPOINTS ARE STILL WELL BELOW FREEZING...AND SURFACE WINDS WILL SWING AROUND TO EAST AND NORTHEAST OVERNIGHT. THEREFORE...WILL ISSUE A WINTER WEATHER ADVISORY FOR A ROW OF COUNTIES SOUTH OF THE SNOW ADVISORY. REALLY DIFFICULT TO DRAW THE FREEZING LINE EVEN 12 HOURS AHEAD OF TIME...BUT OUR ADVISORY WILL BE BASED LARGELY ON THE 18Z RUC SURFACE TEMPERATURES AND SHORT RANGE ENSEMBLE 850 MB TEMPS. WHILE MOST AREAS WILL SEE ADDITIONAL PRECIP...THERE IS STILL BELOW AVERAGE CONFIDENCE IN WHERE TO PLACE THE HIGHEST AMOUNTS. THE NAM HAS LATCHED ONTO THE LOW LEVEL FRONTOGENESIS NEAR THE RED RIVER...WHILE THE GFS PAINTS MORE SNOW ALONG THE MID LEVEL FRONT FROM WESTERN INTO CENTRAL OKLAHOMA. BOTH AREAS ARE LIKELY TO SEE LIGHT ACCUMULATIONS...BUT THE MORE CONSISTENT SIGNAL...AND LESS CHANCE FOR MELTING IS WITH THE ACTIVITY FORECAST TO SURROUND INTERSTATE 40 BOTH NORTH AND SOUTH. WILL CONTINUE WITH OUR FORECAST OF 1 TO 3 INCHES OF SNOW OVER A BROAD AREA...BUT MESOSCALE BANDING AND/OR SOME WEAK CONVECTION MAY LEAD TO HIGHER TOTALS IN SMALL AREAS. WHATEVER DOES FALL WILL LIKELY REMAIN ON THE GROUND THROUGH THE WEEKEND...AS THURSDAY AFTERNOON AND NIGHT REMAIN CLOUDY...AND AN ARCTIC FRONT ARRIVES FRIDAY. LOW LEVEL MOISTURE WILL ALSO LINGER IN THE AREA LATE THURSDAY...AND LIGHT SNOW OR FREEZING RAIN SEEMS A POSSIBILITY. WILL INCREASE TO CHANCE POPS ALONG THE STALLED LOW LEVEL FRONT NEAR THE RED RIVER...AND ALONG THE APPROACHING ARCTIC FRONT IN THE NORTHWEST. EXPECT THIS PRECIP WOULD BE LIGHT...BUT AS WE HAVE SEEN...IT DOES NOT TAKE MUCH TO CAUSE PROBLEMS. IN THE EXTENDED...THE LONGWAVE PATTERN SEEMS UNLIKELY TO BUDGE...WITH WHAT LOOKS LIKE AN OMEGA BLOCK ON AN UNUSUALLY LARGE SCALE...FROM THE PACIFIC ACROSS NORTH AMERICA. THE RIDGE IN THE BLOCK MAY TEND TO MOVE EAST BUT ALSO BE BATTED BACK BY LOW LEVEL COLD AIR INTRUSIONS OUT OF CENTRAL CANADA. SO WILL CONTINUE A COOL FORECAST...BUT WITH A VERY SLOW WARMING TREND. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 27 32 20 26 / 90 70 20 30 HOBART OK 27 31 21 28 / 90 40 30 30 WICHITA FALLS TX 32 36 26 32 / 80 40 30 30 GAGE OK 20 29 16 21 / 60 20 30 30 PONCA CITY OK 21 29 16 22 / 60 50 20 20 DURANT OK 32 38 28 35 / 80 70 30 20 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR OKZ014>019-021>032-040-042. SNOW ADVISORY UNTIL 12 PM CST THURSDAY FOR OKZ014>019-021>044. SNOW ADVISORY UNTIL 12 PM CST THURSDAY FOR OKZ004>013-020. WINTER WEATHER ADVISORY UNTIL 12 PM CST THURSDAY FOR OKZ045>048- 051-052. TX...SNOW ADVISORY UNTIL 12 PM CST THURSDAY FOR TXZ083. WINTER WEATHER ADVISORY UNTIL 12 PM CST THURSDAY FOR TXZ084>086. && $$ BURKE/SIX ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MEMPHIS TN 342 PM CST WED JAN 31 2007 .UPDATE... QUICK UPDATE TO ADD MISSISSIPPI COUNTY IN ARKANSAS AND LAKE...DYER AND OBION COUNTIES IN TENNESSEE TO THE SNOW ADVISORTY. RADAR AND SURFACE TRENDS INDICATE THE SNOW MOVING EAST. ROAD CONDITIONS GETTING SLIPPERY VERY QUICKLY DUE TO COLD TEMPERATURES. LATEST RUC MODEL SOME HELP WITH PROGRESSION OF SNOWFALL...BUT STRONGER LOW LEVEL COLD AIR THAN ANTICIPATED PROVIDING BETTER THAN FORECAST ISENTROPIC UPGLIDE FOR LIFTED MOTION && .PREV DISCUSSION... /ISSUED 302 PM CST WED JAN 31 2007/ SYNOPSIS... COLD HIGH RETREATING OFF THE EAST COAST. RADAR TRENDS SHOW PRECIPITATION BREAKING OUT ACROSS THE PLAINS AND ARKANSAS THIS AFTERNOON. WITH THE LOW LEVELS SO DRY...MUCH OF THE PRECIPITATION INDICATED ON RADAR IS NOT REACHING THE GROUND. HOWEVER OVER NORTHEAST ARKANSAS IT IS. WITH LOW LEVELS SO COLD SNOWFALL ACCUMULATING ON ROADS FAST. ACTUAL TEMPERATURES COLDER THAN THE MODELS BY GENERALLY 5 DEGREES. WITH MODELS NOT HANDLING THE LOW LEVEL TEMPERATURES AT THIS TIME THIS MAY HAVE IMPLICATIONS TO OUR SHORT TERM FORECAST. SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT)... RADAR TRENDS SHOW SNOWFALL TO CONTINUE OVER NORTHEAST ARKANSAS FOR SOME TIME. ACCUMULATIONS OF AROUND AN INCH ARE EXPECTED. WITH TEMPS IN THE LOWER 20S ALL OF THE SNOW IS STICKING NICELY. HAVE DECIDED TO GO WITH AN ADVISORY THROUGH MID-MORNING THURSDAY. FOR THE REST OF THE AREA MIXED PRECIPITATION EXPECTED AFTER MIDNIGHT THROUGH THURSDAY FOR MUCH OF THE MID-SOUTH. MUCH OF THE LIFT FOR THIS EVENT IS ISENTROPIC AND BROAD IN NATURE. ALTHOUGH JET STREAK IS FAIRLY STRONG THERE IS LITTLE IN THE WAY OF SURFACE CYCLOGENESIS. CONSEQUENTLY PRECIPITATION AMOUNTS WILL BE BROAD AND LIGHT THROUGH THURSDAY NIGHT. REGARDLESS...IT DOESN`T TAKE MUCH WINTER PRECIPITATION TO CAUSE TRAVEL ISSUES IN THE MIDSOUTH. THIS COUPLED WITH THE FIRST EVENT OF THE SEASON AND WE HAVE A NEED TO PINPOINT THE IMPACTS. OUR PRECIPITATION WILL COME IN TWO BURSTS. TONIGHT...MIXED PRECIPITATION IS EXPECTED TO DEVELOP WITH THE HEAVIEST OCCURRING IN NORTHEAST MISSISSIPPI IN THE LOCATION OF THE BEST ISENTROPIC LIFT AND MOISTURE. THE PROBLEM IS THERMAL PROFILES INDICATE AN ONSET OF FREEZING RAIN FROM FULTON TO TUPELO TO OXFORD. THIS IS WHERE TRAVEL WILL BE IMPACTED MOST WITH PRECIPITATION TURNING OVER TO RAIN LATER ON THURSDAY. AN ADVISORY WILL BE NEEDED IN THIS AREA LATE TONIGHT AND EARLY THURSDAY. TO THE NORTH AND NORTHWEST OF THIS AREA...THE PRECIPITATION SHOULD BEGIN AS SNOW...HOWEVER AMOUNTS ARE IN QUESTION WITH ACCUMULATIONS RANGING FROM AN INCH TO ONLY A DUSTING. THIS MAKES IT HARD TO DETERMINE WHETHER WE SHOULD ISSUE AN ADVISORY. FOR NOW WE`LL HOLD OFF AND WAIT ON ANY WIDESPREAD ADVISORIES...EXCEPT IN NORTHEAST ARKANSAS AND MISSOURI BOOTHEEL...UNTIL WE CAN GET A BETTER HANDLE ON THE EVOLUTION OF THE PRECIPITATION AMOUNTS. THURSDAY AND THURSDAY NIGHT ARE PROBLEMATIC. ANOTHER WEAK SHORTWAVE MOVES INTO MS/AL RESULTING IN PRECIPITATION REDEVELOPING IN THE AFTERNOON. AGAIN QUESTION WILL BE THE TYPE. FOR NOW BELIEVE THE MODEL THERMAL PROFILES MAY BE TOO WARM IN THE LOWER LEVELS (THEY SUGGEST A DRY ADIABATIC PROFILE WITH PRECIPITATION?) WILL KEEP RAIN FOR THE SOUTH THIRD OF THE FORECAST AREA...A MIX OF THE MIDDLE THIRD AND ALL SNOW TO THE NORTH. AGAIN PRECIPITATION AMOUNTS WILL BE LIGHT...BUT DEPENDING ON HOW TEMPERATURES PLAY OUT A WINTER WEATHER ADVISORY MAY BE NEEDED. WILL USE THE UKMET/GFS/CANADIAN FOR THURSDAY NIGHT AND FRIDAY. NAM IS TOO SLOW WITH COLD AIR SEEPING IN. CONSEQUENTLY WILL GO LOWER THAN GUIDANCE WITH FLURRIES POSSIBLE IN THE STRONG COLD AIR ADVECTION. OVERALL THE TEMPERATURE GUIDANCE THROUGH THIS PERIOD LOOKS WARM. BUT THIS SHOULD NOT BE SURPRISING WITH LOW LEVEL COLD AIR IN PLACE. ...BELLES... LONG TERM (SATURDAY THROUGH WEDNESDAY)...LONG RANGE MODELS IN GENERAL AGREEMENT WITH AN ARCTIC LOW PINWHEELING AROUND HUDSON BAY THROUGH THE PERIOD AND A LONGWAVE TROUGH MOVING THROUGH THE LOWER MISSISSIPPI VALLEY ON SUNDAY. ANOTHER COLD FRONT WILL MOVE THROUGH THE REGION ON MONDAY WITH COLD HIGH PRESSURE BUILDING BACK INTO THE AREA FOR NEXT WEEK. ADJUSTED TEMPERATURES TOWARD THE LOW END OF THE GFS ENSEMBLE GUIDANCE SINCE OPERATIONAL GFS NUMERICAL GUIDANCE SEEMS TO BE TOO WARM THIS WEEKEND INTO EARLY NEXT WEEK BASED ON UPPER AIR PATTERN AND VERY COLD 850MB TEMPERATURES. ...CJC... && .PRELIMINARY POINT TEMPS/POPS... MEM 27 38 30 38 / 80 100 60 10 MKL 23 36 28 35 / 80 90 60 10 JBR 20 34 24 34 / 80 90 60 10 TUP 29 39 33 41 / 90 100 60 10 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...SNOW ADVISORY UNTIL 9 AM CST THURSDAY FOR CLAY-CRAIGHEAD-GREENE- LAWRENCE-MISSISSIPPI-RANDOLPH. MO...SNOW ADVISORY UNTIL 9 AM CST THURSDAY FOR DUNKLIN-PEMISCOT. MS...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM CST THURSDAY FOR ALCORN-BENTON(MS)-ITAWAMBA-LAFAYETTE-LEE(MS)- MARSHALL-PONTOTOC-PRENTISS-TIPPAH-TISHOMINGO-UNION. TN...SNOW ADVISORY UNTIL 9 AM CST THURSDAY FOR DYER-LAKE-OBION. WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM CST THURSDAY FOR HARDEMAN-HARDIN-MCNAIRY. && $$ tn