AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PUEBLO CO 954 AM MST THU DEC 4 2008 .UPDATE... HAVE ADDED THE HIGHER ELEVATIONS OF THE WET MOUNTAINS AND THE SANGRE DE CRISTO RANGE TO THE SNOW ADVISORY. SHOULD SEE AT LEAST LOW END ADVISORY AMOUNTS OVER MUCH OF THE EASTERN MOUNTAINS. SOME LIGHT SHSN MOVING THRU PUEBLO COUNTY RIGHT NOW BUT AM NOT EXPECTING MUCH IN THE WAY OF ACCUMULATIONS. MAIN SNOWFALL SHOULD BE LATER THIS AFTERNOON AND EARLY EVE OVER THE ERN MTS...AND THE HYR TRRN W OF I-25. ROSE && .PREV DISCUSSION... /ISSUED 435 AM MST THU DEC 4 2008/ SHORT TERM... ..SHORT TERM CONCERNS REMAIN SNOW AMOUNTS AND COLD TEMPS... CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING MODERATE WEST TO NORTHWEST FLOW ALOFT WITH A BROAD UPPER TROUGH ELONGATING ACROSS THE STATE. REGION RADARS INDICATING WIDESPREAD LIGHT SNOW SPREADING ACROSS NORTHERN COLORADO ASSOCIATED WITH RR QUAD OF JET CORE TRANSLATING ACROSS THE NORTHERN ROCKIES ATTM. AT THE SFC...COLD HIGH PRESSURE CONTINUES TO BUILD ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS WITH LOW LEVEL UPSLOPE KEEPING MVFR CLOUD DECK IN PLACE AND TEMPERATURES MAINLY IN THE 20S ACROSS EASTERN COLORADO ATTM. TODAY AND TONIGHT...NOT MUCH CHANGE IN FORECAST THINKING WITH SWATH OF WIDESPREAD SNOWFALL EXPECTED TO SLOWLY DRIFT SOUTH AND EAST ACROSS THE SOUTHCENTRAL AND SOUTHEAST COLORADO THROUGH TONIGHT AS JET CORE CONTINUES TO TRANSLATE ACROSS THE STATE...THOUGH HAVE INCREASED POPS ACROSS THE FAR SE PLAINS FOR THIS MORNING WITH SATELLITE INDICATING COOLING CLOUD TOPS AND LATEST NAM PRINTING OUT SOME LIGHT WAA QPF FOR THE MORNING. WITH PERSISTENT GENERALLY LIGHT SNOWFALL ACROSS THE CENTRAL MTS HAVE ISSUED WINTER WEATHER ADVISORY FOR ANOTHER 3 TO 6 INCHES ACROSS ZONE 59 AND NORTHERN PORTIONS OF ZONE 60 THROUGH 03Z. HAVE ALSO ISSUED AN ADVISORY FOR TELLER COUNTY FROM 18Z THROUGH 06Z WITH 4 TO 8 INCHES OF FLUFFY SNOW POSSIBLE. MAY NEED AN ADVISORY FOR PORTIONS OF WET AND SANGRE DE CRISTO MTS...THOUGH WITH THE BULK OF THE SNOWFALL NOT EXPECTED TO START UNTIL LATE THIS AFTERNOON AND LATEST NAM KEEPING H7 FLOW LIGHT WESTERLY...WILL LET NEXT SHIFT DECIDE IF IT IS NEEDED. AT ANY RATE...CURRENT GRIDS HAVE 2 TO 5 INCHES ACROSS ALONG AND WEST OF THE I-25 CORRIDOR WITH 1 TO 3 INCHES ACROSS THE REST OF THE PLAINS. SNOW EXPECTED TO TAPER OFF FROM WEST TO EAST THROUGH THE LATE EVENING WITH SUBSIDENT BEHIND PASSING WAVE. AS FOR TEMPS...WITH CONTINUED CLOUD COVER...SHOULD SEE NEAR STEADY TEMPS THROUGH THE LATE MORNING WITH COOLING THROUGH THE AFTERNOON. HAVE STAYED CLOSE TO GUIDANCE FOR OVERNIGHT LOWS...THOUGH IF CLOUDS CLEAR EARLY THAN EXPECTED...TEMPERATURES WILL BE COLDER THAN FORECAST. -MW LONG TERM... (FRI-WED) MAIN CONCERN THIS FCST PERIOD WILL BE ANOTHER WX SYSTEM WHICH WILL ONCE AGAIN BRING THE THREAT OF ACCUM SNOW TO MOST OF THE REGION DURING THE MONDAY/EARLY TUESDAY TIME FRAME. IN THE MEANTIME...WX SYSTEM WHICH WILL AFFECT THE WX IN THE SHORT TERM (ABOVE) SHOULD BE OUT OF THE REGION BY FRIDAY MORNING WITH SKIES BECOMING PARTLY CLOUDY/MOSTLY SUNNY OVER THE REGION BY EARLY FRIDAY AFTERNOON. TEMPS ON FRIDAY WILL RECOVER AS COMPARED TO TODAY...BUT IT STILL WILL BE ON THE COOL SIDE WITH TEMPS MAINLY IN THE LOWER 40S ACROSS THE PLAINS. THE WEEKEND SHOULD BE RELATIVELY NICE AND MAINLY DRY AS MODEST NW FLOW ALOFT CONTINUES OVER THE REGION. ANTICIPATE TEMPS MAINLY IN THE 50S/AROUND 60 ON THE PLAINS THESE TWO DAYS. AS FOR MONDAY...ALL OF THE LONGER RANGE MODELS SHOW ANOTHER SHORTWAVE DROPPING ACROSS THE REGION DURING THIS TIME PERIOD. EC IS A BIT STRONGER THAN THE GFS AND SHOWS MORE PROMISE FOR PRECIP ON THE PLAINS AS THE 700 MB WINDS ON THIS GUIDANCE PRODUCT GO NE FOR A PERIOD OF TIME. SNOWS SHOULD BEGIN ACROSS THE C MTNS BY EARLY MONDAY...WITH THE PRECIP DROPPING S ACROSS THE PLAINS DURING THE DAYTIME PERIOD. IT APPEARS THE BEST CHANCE OF SNOW ALONG THE POPULATION CENTERS OF SE CO WILL BE LATER MONDAY INTO MONDAY NIGHT. AT THIS TIME SEVERAL INCHES OF SNOW WILL BE POSSIBLE...ESPECIALLY IF THE EC COMES CLOSER TO VERIFYING. TEMPS ON MONDAY WILL BE TRICKY...ESPECIALLY IF THE FRONT COMES DOWN LATER IN THE DAY. FOR NOW LEFT TEMPS AS IS AND WILL LET LATER SHIFTS ADJUST ACCORDINGLY. BY TUESDAY...MOST OF THE WX SHOULD BE OUT OF THE REGION WITH CLEARING SKIES. WED ANOTHER WX SYSTEM WILL BE APPROACHING THE REGION WHICH MAY BRING ANOTHER CHANCE OF PRECIP TO THE C MTNS AND POSSIBLY THE PLAINS. /34 AVIATION... MVFR AND PATCHY IFR CIGS EXPECTED ACROSS THE EASTERN PLAINS THROUGH THE MORNING WITH IFR AND LIFR CONDITIONS WITH SNOW ACROSS THE CENTRAL MTS. IFR CONDITIONS EXPECTED ACROSS THE EASTERN MTS LATE THIS MORNING AND ACROSS THE SOUTHEAST PLAINS THIS AFTERNOON AND TONIGHT AS SNOW SPREADS SOUTH AND EAST ACROSS THE AREA THROUGH TONIGHT. -MW && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR COZ072>075-080>082. WINTER WEATHER ADVISORY UNTIL 8 PM MST THIS EVENING FOR COZ058- 060. && $$ 44/06 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 435 AM MST THU DEC 4 2008 .SHORT TERM... ...SHORT TERM CONCERNS REMAIN SNOW AMOUNTS AND COLD TEMPS... CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING MODERATE WEST TO NORTHWEST FLOW ALOFT WITH A BROAD UPPER TROUGH ELONGATING ACROSS THE STATE. REGION RADARS INDICATING WIDESPREAD LIGHT SNOW SPREADING ACROSS NORTHERN COLORADO ASSOCIATED WITH RR QUAD OF JET CORE TRANSLATING ACROSS THE NORTHERN ROCKIES ATTM. AT THE SFC...COLD HIGH PRESSURE CONTINUES TO BUILD ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS WITH LOW LEVEL UPSLOPE KEEPING MVFR CLOUD DECK IN PLACE AND TEMPERATURES MAINLY IN THE 20S ACROSS EASTERN COLORADO ATTM. TODAY AND TONIGHT...NOT MUCH CHANGE IN FORECAST THINKING WITH SWATH OF WIDESPREAD SNOWFALL EXPECTED TO SLOWLY DRIFT SOUTH AND EAST ACROSS THE SOUTHCENTRAL AND SOUTHEAST COLORADO THROUGH TONIGHT AS JET CORE CONTINUES TO TRANSLATE ACROSS THE STATE...THOUGH HAVE INCREASED POPS ACROSS THE FAR SE PLAINS FOR THIS MORNING WITH SATELLITE INDICATING COOLING CLOUD TOPS AND LATEST NAM PRINTING OUT SOME LIGHT WAA QPF FOR THE MORNING. WITH PERSISTENT GENERALLY LIGHT SNOWFALL ACROSS THE CENTRAL MTS HAVE ISSUED WINTER WEATHER ADVISORY FOR ANOTHER 3 TO 6 INCHES ACROSS ZONE 59 AND NORTHERN PORTIONS OF ZONE 60 THROUGH 03Z. HAVE ALSO ISSUED AN ADVISORY FOR TELLER COUNTY FROM 18Z THROUGH 06Z WITH 4 TO 8 INCHES OF FLUFFY SNOW POSSIBLE. MAY NEED AN ADVISORY FOR PORTIONS OF WET AND SANGRE DE CRISTO MTS...THOUGH WITH THE BULK OF THE SNOWFALL NOT EXPECTED TO START UNTIL LATE THIS AFTERNOON AND LATEST NAM KEEPING H7 FLOW LIGHT WESTERLY...WILL LET NEXT SHIFT DECIDE IF IT IS NEEDED. AT ANY RATE...CURRENT GRIDS HAVE 2 TO 5 INCHES ACROSS ALONG AND WEST OF THE I-25 CORRIDOR WITH 1 TO 3 INCHES ACROSS THE REST OF THE PLAINS. SNOW EXPECTED TO TAPER OFF FROM WEST TO EAST THROUGH THE LATE EVENING WITH SUBSIDENT BEHIND PASSING WAVE. AS FOR TEMPS...WITH CONTINUED CLOUD COVER...SHOULD SEE NEAR STEADY TEMPS THROUGH THE LATE MORNING WITH COOLING THROUGH THE AFTERNOON. HAVE STAYED CLOSE TO GUIDANCE FOR OVERNIGHT LOWS...THOUGH IF CLOUDS CLEAR EARLY THAN EXPECTED...TEMPERATURES WILL BE COLDER THAN FORECAST. -MW .LONG TERM... (FRI-WED) MAIN CONCERN THIS FCST PERIOD WILL BE ANOTHER WX SYSTEM WHICH WILL ONCE AGAIN BRING THE THREAT OF ACCUM SNOW TO MOST OF THE REGION DURING THE MONDAY/EARLY TUESDAY TIME FRAME. IN THE MEANTIME...WX SYSTEM WHICH WILL AFFECT THE WX IN THE SHORT TERM (ABOVE) SHOULD BE OUT OF THE REGION BY FRIDAY MORNING WITH SKIES BECOMING PARTLY CLOUDY/MOSTLY SUNNY OVER THE REGION BY EARLY FRIDAY AFTERNOON. TEMPS ON FRIDAY WILL RECOVER AS COMPARED TO TODAY...BUT IT STILL WILL BE ON THE COOL SIDE WITH TEMPS MAINLY IN THE LOWER 40S ACROSS THE PLAINS. THE WEEKEND SHOULD BE RELATIVELY NICE AND MAINLY DRY AS MODEST NW FLOW ALOFT CONTINUES OVER THE REGION. ANTICIPATE TEMPS MAINLY IN THE 50S/AROUND 60 ON THE PLAINS THESE TWO DAYS. AS FOR MONDAY...ALL OF THE LONGER RANGE MODELS SHOW ANOTHER SHORTWAVE DROPPING ACROSS THE REGION DURING THIS TIME PERIOD. EC IS A BIT STRONGER THAN THE GFS AND SHOWS MORE PROMISE FOR PRECIP ON THE PLAINS AS THE 700 MB WINDS ON THIS GUIDANCE PRODUCT GO NE FOR A PERIOD OF TIME. SNOWS SHOULD BEGIN ACROSS THE C MTNS BY EARLY MONDAY...WITH THE PRECIP DROPPING S ACROSS THE PLAINS DURING THE DAYTIME PERIOD. IT APPEARS THE BEST CHANCE OF SNOW ALONG THE POPULATION CENTERS OF SE CO WILL BE LATER MONDAY INTO MONDAY NIGHT. AT THIS TIME SEVERAL INCHES OF SNOW WILL BE POSSIBLE...ESPECIALLY IF THE EC COMES CLOSER TO VERIFYING. TEMPS ON MONDAY WILL BE TRICKY...ESPECIALLY IF THE FRONT COMES DOWN LATER IN THE DAY. FOR NOW LEFT TEMPS AS IS AND WILL LET LATER SHIFTS ADJUST ACCORDINGLY. BY TUESDAY...MOST OF THE WX SHOULD BE OUT OF THE REGION WITH CLEARING SKIES. WED ANOTHER WX SYSTEM WILL BE APPROACHING THE REGION WHICH MAY BRING ANOTHER CHANCE OF PRECIP TO THE C MTNS AND POSSIBLY THE PLAINS. /HODANISH && .AVIATION... MVFR AND PATCHY IFR CIGS EXPECTED ACROSS THE EASTERN PLAINS THROUGH THE MORNING WITH IFR AND LIFR CONDITIONS WITH SNOW ACROSS THE CENTRAL MTS. IFR CONDITIONS EXPECTED ACROSS THE EASTERN MTS LATE THIS MORNING AND ACROSS THE SOUTHEAST PLAINS THIS AFTERNOON AND TONIGHT AS SNOW SPREADS SOUTH AND EAST ACROSS THE AREA THROUGH TONIGHT. -MW && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 8 PM MST THIS EVENING FOR COZ058- 060. WINTER WEATHER ADVISORY FROM 11 AM THIS MORNING TO 11 PM MST THIS EVENING FOR COZ081-082. && $$ 23/34 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 1244 AM EST FRI DEC 5 2008 .SYNOPSIS... OVER THE NEXT FEW DAYS A SERIES OF FAST MOVING SYSTEMS WILL INFLUENCE OUR WEATHER. A COLD FRONT WILL SLIDE OFFSHORE THIS EVENING. HIGH PRESSURE WILL BUILD INTO THE OHIO VALLEY FRIDAY AND DRIFT OFFSHORE SATURDAY...BUT PRODUCE A COLD FLOW OF AIR ACROSS THE GREAT LAKES. SATURDAY NIGHT AND SUNDAY A CLIPPER TYPE LOW PRESSURE AREA WILL RACE ACROSS SOUTHEAST CANADA...DRAGGING YET ANOTHER COLD CDFNT THROUGH THE REGION...AND BRING SOME LIGHT SNOW. SUNDAY NIGHT INTO MONDAY AN ARCTIC HIGH PRESSURE AREA WILL MOVE EAST FROM THE GREAT LAKES ACROSS OUR REGION. MIDWEEK A RATHER COMPLEX STORM SYSTEM WILL HEAD OUR WAY FROM THE TENNESSEE VALLEY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... OVERNIGHT PER THE RUC13 AND NAM12/18Z SUGGESTS THAT SHEAR WILL NOT ONLY CONTINUE BUT BECOME MORE NORTHWEST OVERNIGHT. THIS HAS RESULTED IN A SHIFT SOUTHWARD OF THE EXPECTED LAKE BAND AND WILL EXPAND THE ADVISORY INTO SOUTHERN HERKIMER COUNTY. THIS BAND IS EXPECTED TO LIFT NORTHWARD AROUND SUNRISE AND COULD POSE AN ISSUE ALONG THE THRUWAY MORNING COMMUTE. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY/... FRIDAY AND FRI NIGHT THE BAND FLUCTUATES BTWN 280 AND 250 DEG...PUTTING MUCH OF N HERKIMER AND W HAMILTON COS IN PERIODS OF LAKE EFFECT SNOW. THIS FIRE HOUSE EFFECT WILL KEEP THE EVENT FROM REACHING WARNING CRITERIA AS THE SNOW IS SPREAD OVER A WIDER AREA. AWAY FROM THE LAKES UNDER HIGH PRESSURE AND SUBSIDENCE FAIR WEATHER EXPECTED...BUT MOISTURE AND CLOUDS OFF THE LAKES WILL KEEP IT MORE PARTLY CLOUDY THAN CLEAR. FRIDAY NIGHT SFC RIDGE SETS UP FM MAINE TO W VA. LAKE EFFECT DIMINISHES AS UPPER SUPPORT ENDS...AND THE WHATS LEFT IS TURNED TWRD SAINT LAWRENCE VALLEY AS H850 FLOW BCMS SW. JUST ABOUT IDEAL RADIATION CONDITIONS FRI NT AND WILL TAKE MINS SEVERAL DEGREES BLO MODEL BLEND. SAT WILL START FAIR...BUT CLOUDS ASSOC WITH WAA AHEAD OF APPROACHING CLIPPER SYSTEM WILL MOVE INTO REGION LATER IN THE DAY. THE NAM IS SLOWER WITH THIS BY 3-6 HOURS...BUT BOTH MDLS HOLD PCPN OFF TILL EVENING. THE CLIPPER SFC LOW MOVES THROUGH THE E GRTLKS AS A SERIES OF 500HPA SHORT WAVES CARVE OUT A NEGATIVELY TILED TROF AT THAT LEVEL FM THE GRTLKS TO MID ATLC. FCA IS IN WAA AREA BETWEEN SFC LOW OVER E GRTLKS AND DEVELOPING OFFSHORE COASTAL LOW SAT NT INTO SUNDAY. THE MAIN OCCLUDED AXIS IS EAST OF FCA SUNDAY MORNING. HWVR THE GFS/NAM SHOWS CONTINUING WIDESPREAD -SHSN IN CAA MAINLY N & W OF ALB. WHILE CONDS IN LOWER LEVELS ARE NOT INDICATIVE OF LK RESPONSE INTO OUR AREA...(N-NNW FLOW)...THIS PCPN IS MAINLY DRIVEN BY THE STRENGTH OF THE 500 HPA TROF. NAM IS STILL A TAD FASTER ENDING THIS EVENT. MUCH OF AREA WILL SEE -SN...WITH AN INCH OR SO POSSIBLE VALLEYS AND A FEW INCHES IN HIGHER ELEVATIONS...PARTICULARLY ADIRONDACKS. THE ENSEMBLES HAVE TWO OUTLIERS THAT WOULD INDICATE A 6 INCH SNOW STORM...BUT THEY ARE OUTLIERS. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... SFC LOW PRESSURE SYSTEM WILL MOVE OUT OF THE AREA WITH A MOSTLY DRY BUT COLD SUNDAY NIGHT...LEADING INTO A DRY MONDAY TO START OFF THE PERIOD. MONDAY TEMPS WILL TRY TO BREAK FREEZING...WITH 850 TEMPS IN THE NEGATIVE TEENS. HIGH PRESSURE WILL BUILD INTO THE NORTHEAST ON MONDAY ALLOWING FOR MOSTLY SUNNY SKIES. THIS WILL QUICKLY BE FOLLOWED BY ANOTHER LOW PRESSURE SYSTEM MONDAY NIGHT. INCREASED POPS TO SLGT CHC AND CHC OVERNIGHT. GFS A LITTLE FASTER THAN ECMWF AND DGEX WITH ONSET OF PRECIP. GFS HAS H500 CLOSED LOW IN MANITOBA WITH A TROUGH OVER THE PLAIN STATES HELPING TO FEED MOISTURE THE SFC LOW MOVING TOWARDS TENNESSEE. THE H500 LOW WILL DEEPEN AS THE SFC LOW CONTINUES TO MOVE NORTHEAST...SPLITTING BY WED MORNING...BECOMING A DOUBLE BARREL CLOSED LOW SYSTEM. THIS COMPLEX SYSTEM WILL LEAD TO ANOTHER MIXED PRECIP EVENT. THIS DEEP LOW WILL ALSO BRING STRONG COLD AIR...WITH MAX TEMPS ON THURSDAY IN THE M20S. 12Z ECMWF HAS LESS COMPLEX SYSTEM...WITH SLOWER PROGRESSION...AND WARMER TEMPS FROM A MORE BROAD TROUGH. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... VFR CONDITIONS EXPECTED AT ALL TAF SITES THROUGH 06Z SATURDAY WITH MAINLY SKC CONDITIONS EXPECTED FOR THE REMAINDER OF THE OVERNIGHT PERIOD AS ANY LAKE EFFECT CLOUDS AND SNOW SHOWERS REMAIN WELL WEST OF THE HUDSON VALLEY. KGFL MAY EXPERIENCE SOME SNOW FLURRIES ASSOCIATED WITH THE LAKE EFFECT THIS AFTERNOON MAINLY BETWEEN 17Z AND 22Z AND WILL CONTINUE VCSH WITH NO SNOW ACCUMULATION EXPECTED. THE LAKE EFFECT SNOWS WILL AFFECT MOSTLY THE ADIRONDACKS AND TUG HILL. GENERALLY EXPECT BKN035 BKN050 DURING DAYTIME HOURS WITH SKIES BECOMING SKC ONCE AGAIN THIS EVENING. WINDS WILL GENERALLY BE W-NW AT 5-8 KTS THROUGH THE PERIOD. OUTLOOK... FRI NGHT-SAT...VFR...NO SIG WX. SAT NGHT-SUN...MVFR/IFR...CHC -SN. MON...VFR...NO SIG WX. TUE...VFR/MVFR...CHC -SHSN/-SHRA. && .HYDROLOGY... NO HYDRO PROBLEMS ARE EXPECTED OVER THE NEXT 5 DAYS. IT WILL TURN MUCH COLDER STARTING LATER TODAY WITH PRECIPITATION CHANGING FROM RAIN TO SNOW. STARTING TONIGHT TEMPERATURES OVER THE REGION WILL AVERAGE WELL BELOW FREEZING INTO EARLY NEXT WEEK WITH HIGHS FROM THE MID TWENTIES TO THE MID THIRTIES AND LOWS FROM THE MID SINGLES TO THE MID TWENTIES. THIS WILL BE FAVORABLE FOR ICE TO FORM AND THICKEN ON RIVERS AND LAKES. FOR DETAILS ON THE RIVERS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST THIS EVENING FOR NYZ032-033-038. MA...NONE. VT...NONE. && $$ SYNOPSIS...SNYDER NEAR TERM...BGM/SNYDER SHORT TERM...BGM/SNYDER LONG TERM...KGS AVIATION...11 HYDROLOGY...RCK ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 415 AM EST FRI DEC 5 2008 .SYNOPSIS... 07Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING A RATHER UNEVENTFUL UPPER LEVEL PATTERN ACROSS THE CONUS EARLY THIS MORNING. NATION IS SPLIT ALOFT BY A STRUNG OUT UPPER TROUGH EXTENDING FROM EASTERN CANADA DOWN THROUGH THE GREAT LAKES AND THEN SOUTHWEST THROUGH THE FOUR CORNERS REGION. UPPER PATTERN ALONG THE CENTRAL/NORTHEAST GULF COAST IS ZONAL IN NATURE WITH OCCASIONAL FAST MOVING AND WEAK DISTURBANCES EMBEDDED WITHIN. ONE SUCH SHORTWAVE CROSSED OVERHEAD THIS PAST EVENING AND IS NOW SHEARING OUT TO THE NORTHEAST LEAVING LITTLE IN THE WAY OF LARGE SCALE FORCING OVERHEAD. AT THE SURFACE...SURFACE TROUGH ASSOCIATED WITH A WEAK COLD FRONT EXTENDS ACROSS THE EASTERN FORECAST AREA FROM THE CAROLINAS TO OUR OFFSHORE WATERS. THIS TROUGH IS MAKING PAINFULLY SLOW PROGRESS EASTWARD AND THIS SLOW MOTION SOUTH AND EAST WILL CONTINUE INTO THE DAYLIGHT HOURS. LOW DECK OF CLOUDS ASSOCIATED WITH THE FRONT COVERS THE ENTIRE FORECAST AREA EARLY THIS MORNING AND IS ALSO SHOWING THE SAME SLOW MOVEMENT EAST. WITH THE UPPER SUPPORT FOR LIFT VERY WEAK AT THIS POINT...REGIONAL RADARS ARE SHOWING ONLY A SCATTERING OF LIGHT SHOWERS ACROSS THE REGION. THESE SHOWERS ARE LARGELY IN A ZONE EAST OF A LINE FROM KPFN TO KABY AND WEST OF A LINE FROM PERRY TO TIFTON. && .SHORT TERM (TODAY THROUGH SUNDAY)... WEAK SURFACE FRONT WILL SLOWLY PUSH SOUTHEAST ACROSS THE EASTERN ZONES DURING THE MORNING HOURS AND EXIT SOUTHEAST OF THE FL BIG BEND EARLY THIS AFTERNOON. THIS FRONT IS UNLIKE SOME OF THE MORE POTENT SURGES SEEN OVER THE PAST FEW WEEKS IN TERMS OF COLD AIR WITH ONLY A SLIGHTLY COOLER AIRMASS IN ITS WAKE. AS WAS MENTIONED IN THE SYNOPSIS ABOVE...MID/UPPER LEVEL SYNOPTIC SUPPORT FOR LIFT IS LIMITED AT BEST THROUGH THE DAY. WITH THIS IN MIND...SUPPORT FOR SHOWERS WILL LARGELY HAVE TO COME FROM THE LOWER LEVELS. CURRENT SHOWERS ACROSS THE MIDDLE OF THE FORECAST AREA ARE FORMING IN A REGION OF WEAK FORCED ASCENT ALONG THE NOSE OF AN 850MB THETA-E RIDGE. GFS/NAM IN AGREEMENT SHOWING THIS RIDGE WEAKENING A BIT DURING THE DAY WHILE SLOWLY PROGRESSING EASTWARD WITH THE FRONT INTO THE EASTERN FLORIDA BIG BEND/SOUTH-CENTRAL GA. WITH THIS IN MIND WILL TAPER POPS OFF ACROSS THE NORTHWEST HALF OF THE AREA FOR THE AFTERNOON HOURS WITH HIGHEST SHOWER CHANCES SOUTH AND EAST OF A LINE FROM APALACHICOLA TO VALDOSTA AFTER 1 OR 2 PM. IF SHOULD BE MENTIONED THAT DESPITE THE RAIN CHANCES...THE OVERALL IMPACT WILL BE LIMITED WITH LIGHT RAINFALL ACCUMULATIONS OF GENERALLY ONLY AROUND ONE TENTH OF AN INCH AT BEST. WHILE THE SOUTHEAST HALF OF THE AREA IS LIKELY TO REMAIN MOSTLY CLOUDY THROUGH THE DAYLIGHT HOURS...FURTHER NORTHWEST WILL SEE IMPROVING CONDITIONS. MOISTURE LEVELS THROUGH THE COLUMN WILL BE SLOWLY SCOURING OUT ACROSS PORTIONS OF SOUTHEAST AL/SOUTHWEST GA AND THE FLORIDA PANHANDLE...ALLOWING FOR INCREASING AMOUNTS OF SUN...ESPECIALLY AFTER NOON. SURFACE FRONT STALLS ACROSS THE NORTH-CENTRAL FL PENINSULA THIS EVENING AND REMAIN IN THIS VICINITY THROUGH TONIGHT. MOST OF THE AREA WILL SEE DRY CONDITIONS TONIGHT WITH THE FRONT A MEMORY OFF TO THE SOUTHEAST. HOWEVER...IN CLOSER PROXIMITY TO THE STALLED FRONT (MAINLY SOUTH AND EAST OF TALLAHASSEE AND VALDOSTA) ACROSS THE EASTERN BIG BEND...LOW LEVEL ISENTROPIC LIFT ALONG THE 290-300K SURFACES SHOULD BE ENOUGH TO SUPPORT A CONTINUED CHANCE OF SCATTERED MAINLY LIGHT SHOWERS. ON TOP OF THIS LOWER LEVEL LIFT...WILL ALSO BE WATCHING ANOTHER WEAK DISTURBANCE ALOFT RACING EASTWARD ALONG THE NORTHEAST GULF COAST. GFS IS SHOWING A QUICK SHOT OF DEEP SYNOPTIC LIFT ASSOCIATED WITH THIS FEATURE TO ADD SUPPORT FOR THE SHOWERS. THIS ADDED LIFT MAY ALSO BE ADD JUST ENOUGH TO RESULT IN A RUMBLE OR TWO OF THUNDER DOWN TOWARD CROSS CITY. IN FACT SHOWALTER INDICES DO DROP TO AROUND ZERO OVER THE SOUTHEAST BIG BEND AFTER MIDNIGHT. A COOLER NIGHT IS IN STORE FOR ALL BEHIND THE FRONT. GRIDS NOW SHOWING 30S OVER THE NW ZONES AND LOWER TO MIDDLE 40S FURTHER SOUTHEAST. THERE ARE GUIDANCE MEMBERS SHOWING A LIGHT FREEZE OVER PORTIONS OF SE AL AND INLAND SECTIONS OF THE FL PANHANDLE. AM A BIT CONCERNED THAT SOME ADDITIONAL CLOUDCOVER ASSOCIATED WITH THE PASSING MID-LEVEL IMPULSE WILL PREVENT THESE TEMPERATURES FROM BEING ACHIEVED AND WILL KEEP THE LOWEST TEMPERATURES FROM DROPPING BELOW FREEZING. EVEN STILL MAY SEE SOME PATCHY FROST IN UNSHELTERED AREA OF THE WEST. SATURDAY AND SATURDAY NIGHT...IMPULSE IN THE MID-LEVELS EXITS TO OUR EAST EARLY ON SATURDAY. WEAK CYCLOGENESIS DURING THIS TIME OFF THE SOUTHEAST COAST WILL BEGIN PULLING THE BOUNDARY FORWARD AGAIN. WILL END POPS ACROSS THE SOUTHEAST BIG BEND BY SUNRISE ON SATURDAY FOR THIS REASON WITH A DRY DAY NOW FORECAST AREA WIDE. WILL BE WATCHING AN AMPLIFYING MID/UPPER LEVEL TROUGH DIGGING INTO THE EASTERN THIRD OF THE NATION LATER SATURDAY AND AT NIGHT. THIS TROUGH WILL FORCE THE NEXT COLD FRONT INTO THE AREA SATURDAY EVENING. MOISTURE WILL BE VERY LIMITED AND EXPECTING A RAPID AND DRY FRONTAL PASSAGE BY SUNRISE. WITH A MIX OF SUN AND CLOUDS IN THE FORECAST SHOULD BE ABLE TO GET AFTERNOON TEMPS UP IN TO THE LOWER 60S NORTH AND MIDDLE 60S SOUTH. COLD AIR ADVECTION BEHIND THE FRONT BRING A STEADY DROP IN TEMPS THROUGH THE OVERNIGHT PERIOD. CURRENT GRIDS SHOWING LOWER TO MIDDLE 30S NORTH AND MIDDLE 30S TO LOWER 40S SOUTH BY SUNRISE. AT THIS TIME THE RIDGE POSITION APPEARS TOO FAR NW TO ALLOW A GOOD RADIATIONAL COOLING SETUP...EVEN IN THE FAR WESTERN ZONES. WILL ONCE AGAIN NOT DROP LOW TEMPS BELOW THE FREEZING MARK. SUNDAY...PLEASANT AND COOL DAY LOOKS IN STORE FOR SUNDAY WITH MOSTLY SUNNY SKIES AND A STEADY NORTHERLY BREEZE. WEAK CAA WILL PREVENT HIGH TEMPERATURES FROM REACHING THE COLUMN POTENTIAL. HOWEVER... STILL FEEL THE MAV IS A TAD COOL AND WILL BUMP UP HIGHS A COUPLE OF DEGREES INTO THE UPPER 50S NORTH AND THE LOWER 60S SOUTH. && .LONG TERM (SUNDAY NIGHT THROUGH FRIDAY)... AFTER A COOL START TO THE DAY ON MONDAY...DEEP LAYER RIDGING WILL DEVELOP OVER THE EASTERN CONUS EARLY NEXT WEEK AS A 500 MB LONG WAVE TROUGH (AND ASSOCIATED FRONTAL SYSTEM) PROPAGATE TOWARD THE EAST. BOTH THE GFS MOS AND GFS BIAS CORRECTED GUIDANCE FORECAST A LIGHT FREEZE MONDAY...BUT THIS SEEMS SOMEWHAT UNLIKELY GIVEN THE POSITION OF THE SURFACE HIGH (ALONG THE VA COAST) AND THE POSSIBILITY OF INCREASING CS SUNDAY NIGHT. THERE ARE CONSIDERABLE DIFFERENCES AMONG THE VARIOUS MODEL SOLUTIONS ON THE TIMING AND INTENSITY OF THIS NEXT SYSTEM...BUT IT APPEARS THAT PORTIONS OF OUR AREA WILL RECEIVE 2 TO 3 INCHES OF RAIN WITHIN THE TUESDAY-THURSDAY MORNING TIME FRAME. THE OPERATIONAL GFS IS SLOWER AND FARTHER SOUTH WITH ITS SURFACE LOW (TRACKING ACROSS SOUTH GA WEDNESDAY) THAN THE GFS ENSEMBLE MEAN AND CMC SOLUTIONS. THE ECMWF SOLUTION IS SLOWER THAN THE OPERATIONAL GFS...AND THE UKMET IMPLIES THE FRONT MAY STALL BY MID WEEK. WE WILL FOLLOW THE OPERATIONAL GFS SOLUTION AS IT IS IN BETWEEN THESE VARYING SOLUTIONS...BUT FORECAST CONFIDENCE IS LOW WHEN IT COMES TO DETAILS BEYOND TUESDAY. ALL OF THE GUIDANCE INDICATE THAT THIS NEXT FRONTAL SYSTEM WILL BE FAIRLY ENERGETIC (REGARDLESS OF THE EXACT TIMING AND TRACK)...WHICH MEANS THERE MAY BE A SLIGHT CHANCE FOR SEVERE WEATHER ANYWHERE FROM TUESDAY NIGHT THROUGH THURSDAY MORNING. HOPEFULLY WE WILL BE ABLE TO PROVIDE MORE DETAIL WHEN (IF) THE MODEL SOLUTIONS CONVERGE. && .MARINE... A WEAK COLD FRONT WILL MOVE WEST TO EAST ACROSS THE FORECAST WATERS INTO THE AFTERNOON HOURS. IN THE WAKE OF THE FRONT EXPECT A WIND SHIFT TO THE NORTH AND NORTHEAST. EXPECTING WINDS IN THE CAUTIONARY LEVEL BEHIND THE FRONT WITH A FEW GUSTS UP OVER 20 KNOTS. OFFSHORE SEAS WILL ALSO BUILD UP TO AROUND 5 FEET...ESPECIALLY ACROSS THE WESTERN LEGS. FRONT WASHES OUT TO OUR SOUTH TONIGHT WITH WINDS AND SEAS DROPPING BELOW CAUTIONARY LEVELS INTO SATURDAY. THE NEXT COLD FRONT WILL RAPIDLY PUSH ACROSS THE WATERS LATER SATURDAY AND SATURDAY NIGHT WITH A PERIOD OF CAUTIONARY TO ADVISORY LEVEL WINDS AND SEAS. THESE ELEVATED WINDS AND SEAS LINGER INTO SUNDAY BEFORE HIGH PRESSURE BUILDS TO OUR NORTH INTO THE EARLY PART OF NEXT WEEK. && .AVIATION... THE 00 UTC GFS MOS APPEAR TO BE UNDER-ESTIMATING THE AMOUNT OF LOW CLOUD COVER OVER OUR REGION. THE BACK EDGE OF THIS MVFR-IFR CLOUD DECK EXTENDS FROM KFFC GA TO KCWF LA...AND WAS MAKING SLOW PROGRESS SOUTHEASTWARD. WE OPTED TO USE THE FORECAST RUC AND NAM SOUNDINGS FOR OUR CLOUD FORECAST AS THAT GUIDANCE HAS INITIALIZED REASONABLY WELL SO FAR...AND MOS SOMETIMES HAS A TENDENCY TO CLEAR LOW CLOUDS OUT TOO QUICKLY IN THESE SITUATIONS. MVFR-IFR CIGS ARE LIKELY AT ALL TAF SITES OVERNIGHT...WITH GRADUAL IMPROVEMENT TO VFR CIGS FROM NORTHWEST TO SOUTHEAST DURING THE MORNING AND EARLY AFTERNOON HOURS. LIGHT DRIZZLE AND/OR LIGHT RAIN WILL AFFECT KTLH...KPFN...AND KVLD DURING THE OVERNIGHT AND EARLY MORNING HOURS...WITH VIS OCCASIONALLY REDUCED TO MVFR. && .FIRE WEATHER... DRIER AIR WILL FILTER INTO WESTERN SECTIONS OF OUR FL PANHANDLE AND SOUTHEAST AL ZONES SATURDAY AFTERNOON...BUT WE DO NOT EXCPECT TO GET THE WIND OR DURATION OF LOW RELATIVE HUMIDITY TO WARRANT A FIRE WEATHER WATCH. RED FLAG CONDITIONS APPEAR POSSIBLE SUNDAY AFTERNOON FOR PORTIONS OF THE AREA...AND A FIRE WEATHER WATCH MAY BE ISSUED TODAY OR TONIGHT. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 61 42 64 36 61 / 50 10 10 0 0 PANAMA CITY 60 43 63 41 61 / 30 10 10 0 0 DOTHAN 57 37 61 35 58 / 10 0 0 0 0 ALBANY 59 37 61 33 59 / 20 10 0 0 0 VALDOSTA 61 44 64 38 60 / 30 20 10 0 0 CROSS CITY 70 48 68 40 64 / 30 40 10 10 0 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE...MROCZKA AVIATION/FIRE WEATHER/LONG TERM...FOURNIER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 245 PM EST THU DEC 4 2008 .SYNOPSIS...VIS IMAGERY SHOWS PLENTY OF CU DEVELOPMENT SHOWING THE SIGNS OF INCREASED MOISTURE OVER THE CWA UNDER SLY FLOW. TEMPS HAVE REACHED THE 70 OVER A LARGE PORTION OF THE AREA WITH A FEW MID 70 DEG READINGS OVER NE FL. FRONTAL BOUNDARY CONTINUES SHIFTING EWD OVER THE SE CONUS WITH A TRAILING AREA OF PRECIP ALONG/AHEAD OF IT FROM NRN GA TO WRN FL PANHANDLE. VORTICITY MAX OVER AL IS QUICKLY MOVING NEWD AND WEAKENING ATTM. BASED ON WATER VAPOR IMAGERY AND RUC DATA SHOULD BEING SEEING PWATS INCREASE TO ABOUT 1 INCH BY THIS EVENING AS THE FRONT NEARS THE AREA. .SHORT TERM...TONIGHT-SUNDAY. TONIGHT...MODELS SHOWING FRONT MOVING INTO THE AREA WITH WEAK LIFT BUT SUFFICIENT MOISTURE TO GENERATE LOW END CHANCE POPS OVER THE NRN ZONES. COMBO OF LIGHT WINDS...COOL OVERNIGHT MINS IN MID 40S TO NEAR 50 AND THE INFLUX OF LOW LEVEL MOISTURE WILL PRODUCE PATCHY TO AREAS OF FOG DEVELOPMENT LATE TONIGHT. FRIDAY...FRONT WILL BE LOCATED FROM SE GA COAST TO SUWANNEE VALLEY AREA PUSHING SLOWLY SEWD WITH GENERALLY LOW POPS EXPECTED. COULD BE SOME ENHANCEMENT TO THE PRECIP BRIEFLY AS A SHORTWAVE PASSES TO THE N OF THE AREA. MAX TEMPS WILL BE FROM NEAR 60 N TO AROUND 70 S/SE ZONES. FRI NIGHT... MID-UPPER LEVEL TROUGHING OVER THE ERN GULF TO TN VALLEY AND UPPER DISTURBANCES WILL HELP THE FRONT PUSH SLOWLY SE BUT SOME WEAK OVERRUNNING UPGLIDE OVER THE SE PORTION WILL STILL SUPPORT ~20% POPS. MIN TEMPS FROM NEAR 40 NEAR ALMA AND LOWER 50S SE ZONES. AMPLE LOW LEVEL MOISTURE AND LIGHT WINDS WILL SUPPORT AREAS OF FOG AGAIN. SATURDAY...FRONT SHOULD BE PUSHING THROUGH ALL THE ZONES WITH ANY PRECIP PROSPECTS FINALLY COMING TO AN END. TEMPS STILL NOT SIGNIFICANTLY COOLER AS THE COOL AIRMASS IS FAIRLY SHALLOW. HOWEVER...CLOUD COVER MAY HINDER DAYTIME HEATING SO TEMPS MAY BE A BIT COOLER THAN ANTICIPATED. SATURDAY NIGHT...LOW-MID LEVEL TROUGHING PUSHES THROUGH WITH FLOW BECOMING MORE NWLY USHERING IN COOLER/DRIER AIR STILL. MINS EXPECTED IN THE MID 30S TO UPPER 40S. SUNDAY...MOSTLY SUNNY BUT COOL UNDER DEEP NW-W FLOW. MAX TEMPS IN THE UPPER 50S TO LOWER 60S. .LONG TERM...MONDAY-THURSDAY. SFC HIGH PRESSURE NW OF THE AREA SUNDAY WILL SHIFT EWD TO THE E COAST NEAR VA/MD ON MONDAY WHILE SFC WINDS TURN NE-E. MAY SEE A FEW SHOWERS NEAR THE COAST MON WITH POPS INCREASING TUE-WED AS A FAIRLY STRONG COLD FRONT AND UPPER LEVEL SUPPORT COME ACROSS THE SRN CONUS INITIALLY ACROSS ARKLATEX AREA 12Z TUE. NOTED 12Z GUIDANCE FROM GFS AND ECMWF ARE IN DISAGREEMENT WITH THE TIMING OF THE UPPER LEVEL TROUGH/SFC FRONT SO NOT TOO CONFIDENT ON ANY ONE SOLUTION. GFS ENSEMBLE IS NOTICEABLE FASTER WITH THE FRONT. HAVE NOT MADE TOO MANY CHANGES TO EXTENDED AND KEPT POPS MAINLY IN THE 30-40% RANGE TUE AND WED AND WILL CONTINUE TO MENTION ISOLD TSTMS. THIS SEEMS REASONABLE CONSIDERING A CONSERVATIVE ESTIMATE OF SSW 850 MB WINDS OF 50 KT AND STRONG LIFT AHEAD OF THE SHORTWAVE TROUGH. MUCH COOLER AND DRIER AIRMASS BEHIND THE FRONT EXPECTED BY THU. && .AVIATION...SCATTERED TO BROKEN DIURNAL CU DECK AROUND 4-5KFT HAS DEVELOPED THIS AFTERNOON ACRS THE FORECAST AREA AND MOST OF IT WILL DIMINISH AFTER SUNSET. AGAIN...THE FORECAST CHALLENGE FOR TONIGHT IS PROBABLE FOG FORMATION IN THE 03Z-06Z TIME FRAME AS TEMPS WILL COOL VERY QUICKLY TOWARD DEWPOINT VALUES THIS EVENING AND LIKELY CROSSOVER AFTERNOON MIXED DEWPOINTS BY 2-4 DEGS AFTER MIDNIGHT. THIS SUGGESTS ANOTHER SET-UP FOR MVFR VSBYS WITH TEMPO IFR VSBYS/LIFR CIGS TOWARD MORNING. ONE CAVEAT WILL BE ADVANCING CLOUD COVER AHEAD OF WEAKENING COLD FRONT THAT IS LIKELY TO BRING IN SOME 5-10KFT BROKEN CIGS AFTER MIDNIGHT THAT MAY HINDER SOME FOG FORMATION...SO HAVE PLAYED IT MIDDLE OF THE ROAD AND NOT TAKEN THIS TAF SET DOWN TO PREDOMINANT IFR VSBYS/LIFR CIGS AND JUST KEPT IN THE TEMPO GROUP FOR NOW. && .MARINE...NO HEADLINES THROUGH SATURDAY AS WEAK COLD FRONT SLIDES INTO THE REGION WITH LIGHT WINDS AND FLAT SEAS EXPECTED TO CONTINUE INTO THE EARLY PART OF THE WEEKEND. HIGH PRESSURE BUILDING IN BEHIND THE COLD FRONT LATE SATURDAY WILL INCREASE NW WINDS TO 15-20 KNOTS AND SEAS OF 3 TO 5 FT BY SAT NIGHT WITH A SLOW DECREASING TREND ON SUNDAY. WINDS WILL VEER TO NE 10-15 KNOTS ON MONDAY WITH SEAS IN THE 2-4 FT RANGE AS HIGH PRESSURE QUICKLY EXITS TO THE EAST OF THE REGION. NEXT MAJOR FRONTAL SYSTEM APPROACHES ON TUESDAY WITH A SHARP INCREASE IN WINDS AND PROBABLY SMALL CRAFT ADVISORY CONDITIONS. && .FIRE WEATHER...NO RED FLAG EVENTS EXPECTED UNTIL SUNDAY AFTERNOON WHEN 3 TO 5 HR DURATIONS BELOW 35 PERCENT WILL BE POSSIBLE IN DRIER AIR BEHIND NEXT COLD FRONT. && .PRELIMINARY POINT TEMPS/POPS... AMG 46 59 40 61 / 30 30 10 10 SSI 51 62 45 60 / 20 30 20 10 JAX 48 67 46 65 / 10 20 20 10 SGJ 50 69 50 66 / 10 20 20 20 GNV 47 70 46 66 / 10 20 20 10 OCF 47 72 46 69 / 10 10 20 20 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...NONE. && $$ SHASHY/HESS/KEEGAN fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 607 AM CST FRI DEC 5 2008 .DISCUSSION... 402 AM CST SHORT WAVE TROUGH MOVING EAST OF THE AREA THIS MORNING...THOUGH ANOTHER WEAK SHORT WAVE DROPPING ACROSS THE NORTHERN LAKES AND UPPER MISSISSIPPI VALLEY THIS MORNING. WEAK LOW LEVEL WARM ADVECTION IN ADVANCE OF THIS FEATURE RESULTING IN SOME CLOUD COVER ACROSS MINNESOTA...IOWA AND WESTERN WISCONSIN EARLY THIS MORNING...AND WITH SOMEWHAT NEUTRAL VERTICAL MOTION FIELD DEPICTED BY BOTH WRF AND GFS UVM TIME/HEIGHT SECTIONS SUSPECT SOME OF THIS CLOUD COVER WILL WORK ITS WAY INTO NORTHERN IL LATE THIS MORNING. MID/HIGH LEVEL CLOUDS TO INCREASE LATER TODAY ANYWAY AS NEXT UPSTREAM SHORT WAVE TROUGH CURRENTLY OVER NORTHERN SASKATCHEWAN DIGS SOUTHEAST INTO MINNESOTA AND TRANSLATES ACROSS FORECAST AREA TONIGHT INTO SATURDAY MORNING. WINDS BACK SOUTH/SOUTHWEST BY EVENING IN ADVANCE OF THIS CLIPPER... WITH DEEP LAYERED VERTICAL MOTION INCREASING TONIGHT. LOOKING ISENTROPICALLY...APPEARS 285 KELVIN SURFACE INTERSECTS STRONGER UVM AND DENDRITIC GROWTH ZONE AROUND -15 C LATE TONIGHT WITH AVERAGE MIXING RATIO DURING THE 09-15Z PERIOD AROUND 2 G/KG. THUS MAX SNOW AMOUNTS AROUND 2 INCHES SEEM REASONABLE. SIMILAR QPF AMOUNTS FROM 00Z WRF/GFS...AND WITH ABOUT A 15:1 SNOW/LIQUID RATIO ALSO SUPPORT GENERALLY A 1-2 INCH OR 1-3 INCH TOTAL SNOWFALL BY THE TIME SHORT WAVE TROUGH AXIS MOVES THROUGH DURING SATURDAY MORNING. SECOND VORT NOTED DROPPING ACROSS NORTHERN LAKES AND WISCONSIN IN WAKE OF THE FIRST MIDDAY SATURDAY...WHICH MAY MAINTAIN SOME VERY WEAK FORCING ACROSS THE AREA INTO THE AFTERNOON HOURS. GIVEN DRYING OF MID/UPPER LEVELS NOTED IN TIME SECTIONS... SHALLOW NATURE OF MOISTURE AND WEAK UVM WOULD INDICATE MAINLY JUST SOME LINGERING FLURRIES OR LIGHT SNOW SHOWERS BEYOND THE MORNING HOURS WITH LITTLE IF ANY ADDITIONAL ACCUMULATION. COLD FRONT PUSHES ACROSS NORTH CENTRAL IL DURING THE MORNING AND THROUGH THE CHICAGO AREA AROUND MIDDAY...WITH GUSTY NORTHWEST WINDS PROVIDING STRONG LOW LEVEL COLD ADVECTION WITH FALLING TEMPS LIKELY IN THE AFTERNOON. UPPER TROUGH MOVES EAST SATURDAY NIGHT...WITH DEEP SUBSIDENCE DEVELOPING AND SURFACE RIDGE APPROACHING THE MISSISSIPPI BY SUNDAY MORNING. SNOW COVER...LOW LEVEL ARCTIC AIR AND POTENTIAL FOR PARTIAL CLEARING TO SEND TEMPS INTO THE SINGLE DIGITS SATURDAY NIGHT. HAVE UNDERCUT COOLEST GUIDANCE A BIT ESPECIALLY NORTH CENTRAL IL WHERE RADIATIVE COOLING CONDITIONS EXPECTED TO BE MOST FAVORABLE. SURFACE RIDGE THEN MOVES ACROSS AREA SUNDAY MORNING WITH SUNSHINE EXPECTED DURING THE MORNING. YET ANOTHER IN THIS RAPID FIRE SERIES OF SHORT WAVES RIPPLES SOUTHEAST ACROSS THE MIDWEST SUNDAY AFTERNOON HOWEVER...WITH BACKING LOW LEVEL FLOW AND RESULTING WARM ADVECTION TO INCREASE MID/HIGH CLOUDS RATHER QUICKLY. THIS WAVE CONTINUES TO DIG SOUTHEAST ACROSS THE AREA SUNDAY NIGHT BRINGING THE POTENTIAL FOR ANOTHER MEASURABLE SNOW. WHILE THIS SHORT WAVE DIGS ACROSS MIDWEST...LONG WAVE TROUGH AMPLIFIES ACROSS THE ROCKIES AND HIGH PLAINS TO OUR WEST. SURFACE LOW DEVELOPS ACROSS TX PANHANDLE REGION WITH INVERTED TROUGH EXTENDING NORTHEAST INTO THE MIDWEST ALONG LOW LEVEL BAROCLINIC ZONE ALONG SOUTHERN PERIPHERY OF ARCTIC AIR. POTENTIAL FOR LIGHT PRECIPITATION LINGERS MONDAY INTO TUESDAY IN VICINITY OF THERMAL GRADIENT AS SERIES OF WEAK NORTHERN STREAM WAVES PASS THROUGH LARGER SCALE TROUGH AXIS WHICH BECOMES QUITE SHEARED AS JET DIGS ACROSS THE WESTERN CONUS. SOME QUESTION AS TO PRECIP TYPE PROVIDED PRECIP DOES OCCUR ESPECIALLY IN MONDAY/MONDAY PERIOD AS SOUTH WINDS AHEAD OF SHEARED TROUGH AND RESULTING LOW LEVEL WARM ADVECTION RESULT IN THERMAL PROFILES WHICH BECOME MARGINAL FOR SNOW ACROSS SOUTHERN HALF OF CWA. GEM AND ECMWF PARTICULARLY MILD AND PUSH 1540 METER 850-700 THICKNESS CONTOUR UP TO AROUND I-88 MONDAY AFTERNOON. GFS REMAINS COOLER AND FORECASTS SNOW AS PREDOMINANT PRECIP TYPE EVEN IN SOUTHERN COUNTIES. FOR NOW WILL MAINTAIN CURRENT FORECAST GFS SLANT WITH CHANCE SNOW...THOUGH WILL HAVE TO MONITOR MODEL TRENDS NEXT FEW RUNS FOR BETTER HANDLE ON THERMAL PROFILES EARLY NEXT WEEK. RATZER && .AVIATION... 605 AM CST 1200 UTC TAFS...INCREASING SNOW POTENTIAL LATE TONIGHT AND BRISK WINDS WILL BE THE MAIN AVIATION FORECAST CONCERNS OVER THE NEXT 24 TO 36 HOURS. A BROAD RIDGE OF HIGH PRESSURE CENTERED ACROSS MISSOURI WILL CONTINUE TO SLOWLY SLIDE EASTWARD TODAY AS NEXT UPPER LEVEL SHORT WAVE TROUGH ACROSS SOUTHWEST CANADA DIGS INTO THE NORTHERN PLAINS THIS AFTERNOON. IN THE NEAR TERM...SOME HIGH END MVFR AND VFR CIGS BETWEEN 3-4K FT ACROSS EASTERN IOWA NOT HANDLED WELL IN NUMERICAL GUIDANCE WILL LIKELY MOVE ACROSS TERMINALS THIS MORNING AND BASED ON SFC OBS AND RUC SOUNDINGS WOULD EXPECTED GENERALLY VFR CIGS AROUND 3500 FT WITH THIS STRATOCU TO AFFECT RFD BY 13Z AND REMAINDER OF TERMINALS IN THE 15Z-16Z TIME FRAME. WEST WINDS AROUND 10 KNOTS THIS MORNING SHOULD BECOME WEST SOUTHWEST BY MID MORNING WITH SOME GUSTS TO 15 TO 20 KNOTS DEVELOPING. WINDS SHOULD CONTINUE TO BACK THIS AFTERNOON AS THE SFC TROUGH MOVES INTO THE NORTHERN PLAINS. AN AREA OF FAIRLY STRONG PRESSURE FALLS IS EXPECTED TO MOVE ACROSS NORTHERN ILLINOIS/SOUTHERN WISCONSIN LATE THIS EVENING AND EXPECTING A PERIOD OF HEIGHTENED GUSTS AS THIS OCCURS...ESPECIALLY AFTER 03Z WHEN SOME GUSTS TO AT LEAST 25 KNOTS WILL BE POSSIBLE. HAVE NOT MADE SIGNIFICANT CHANGES TO TIMING OF SNOW ASSOCIATED WITH THE SOUTHWEST CANADA TROUGH...AFFECTING RFD TOWARD 05Z AND REMAINDER OF TERMINALS BY 06Z OR 07Z. DURING PERIOD OF STEADIEST SNOW AFTER MIDNIGHT...WILL CONTINUE WITH IFR VSBYS AND LOW MVFR CIGS AROUND 1000 FT. CONDITIONS WILL BEGIN TO IMPROVE SATURDAY MORNING AS SFC FRONT PASSES THROUGH TAKING WINDS NORTHWEST...ALTHOUGH CONTINUED LIGHT SNOW IS EXPECTED THROUGH MID MORNING AS A SECONDARY SHORT WAVE DIGS INTO THE WESTERN GREAT LAKES. MARSILI && .MARINE... 310 AM CST THE PARADE OF WEATHER SYSTEMS WILL CONTINUE TO BRING STRONG WINDS TO LAKE MICHIGAN AT LEAST THROUGH EARLY SUNDAY. A BROAD SURFACE HIGH FROM THE CENTRAL/SOUTHERN PLAINS INTO THE MID MS RIVER VALLEY WILL CONTINUE TO SUPPORT A WESTERLY SFC PRESSURE GRADIENT WITH WINDS OF 15 TO 25 KNOTS THIS MORNING. STRONG SURFACE PRESSURE FALLS WILL DEVELOP THIS AFTERNOON ACROSS THE NORTHERN PLAINS AS AN AREA OF LOW PRESSURE MOVES ACROSS NORTHERN MINNESOTA THIS EVENING. THE PRESSURE FALLS WILL STRENGTHEN THE PRESSURE GRADIENT ACROSS LAKE MICHIGAN...AND EXPECTING SOUTHWEST GALES TO 35 KNOTS TO DEVELOP EARLY THIS EVENING ACROSS MOST OF LAKE MICHIGAN. AT THIS TIME WILL CONTINUE THE SMALL CRAFT ADVISORY FOR THE NEARSHORE WATERS...ALTHOUGH DUE TO THE STRENGTH OF THESE PRESSURE FALLS MOVING ACROSS THE REGION...SOME SOUTHWEST GALE GUSTS CANNOT BE RULED OUT EVEN FOR THE NEARSHORE WATERS TONIGHT. THE COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL TRACK ACROSS LAKE MICHIGAN SATURDAY MORNING BRINGING A POTENTIAL OF NORTHWEST GALES LATE SATURDAY MORNING THROUGH SATURDAY NIGHT...ESPECIALLY GIVEN SFC LOW WILL BE DEEPENING EAST OF LAKE MICHIGAN DURING THIS PERIOD. IN TERMS OF HEADLINES...HAVE UPGRADED THE OPEN WATERS GALE WATCH TO A GALE WARNING WHICH WILL BE IN EFFECT FROM EARLY THIS EVENING THROUGH SATURDAY NIGHT. AS MENTIONED...SMALL CRAFT ADVISORY FOR THE NEARSHORE WATERS WILL REMAIN IN EFFECT TONIGHT AND INTO SATURDAY MORNING...AND HAVE ISSUED GALE WATCH FOR THE NEARSHORE WATERS FOR SATURDAY AFTERNOON INTO SATURDAY EVENING FOR THE POTENTIAL OF NORTHWEST GALES. HAZARDOUS WAVES FOR SMALL CRAFT WILL THEN PERSIST INTO SUNDAY. WINDS AND WAVES WILL DIMINISH MORE SUBSTANTIALLY LATER SUNDAY AFTERNOON AND INTO SUNDAY EVENING AS A SFC RIDGE AXIS APPROACHES THE WESTERN GREAT LAKES. MARSILI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...6 PM FRIDAY TO 3 AM SUNDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL NOON SATURDAY. GALE WATCH...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...NOON SATURDAY TO MIDNIGHT SUNDAY. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1209 PM EST FRI DEC 5 2008 .AVIATION... MVFR/LOW VFR STRATO CU OVER THE AREA EXPECTED TO PERSIST UNTIL AFTER DARK WHEN INCRSG SWLY FLOW WILL ADVECT THE LOW CLOUDS OUT OF THE AREA. SOME FLURRIES ACCOMPANYING THE LOW CLOUDS SHOULD MAINLY IMPACT SBN EARLY IN THE PD WITH BACKING WINDS TAKING LAKE EFFECT NORTH OF THE TERMINAL BY 20Z. LOW PRESSURE SYSTEM CENTERED OVER SASK WILL MOVE SE TO LS WITH ASSOCIATED CDFNT MOVG INTO NW INDIANA BY 18Z SAT. HIGH CLOUDS WILL OVERSPREAD THE AREA THIS EVE IN ADVANCE OF THIS SYSTEM AND GRADUALLY LOWER OVERNIGHT WITH CONDITIONS THEN LOWERING TO IFR TOWARD MORNING AS A BAND OF SNOW ACCOMPANYING FRONTAL PASSAGE MOVES THROUGH. && SHORT TERM... TODAY THROUGH SATURDAY LAKE EFFECT SNOW SHOWERS CONTINUE TO IMPACT SW MI THIS MORNING...WITH DOPPLER RADAR ESTIMATIONS OF 2 TO 4 INCHES ACROSS A NARROW SWATH OF BERRIEN AND CASS COUNTIES. OTHERWISE...GENERALLY CLEAR SKIES RE PREVAILING ACROSS THE REGION WITH JUST A FEW CLOUDS AND FLURRIES ARE IN PLACE ACROSS THE FAR SOUTH WHERE A SUBTLE WIND SHIFT IS OCCURRING WITH A WEAK UPPER WAVE. TEMPS ARE GENERALLY IN THE TEENS...SAVE FOR THE FAR NW WHERE LOW 20S ARE PRESENT WITH LAKE MODIFIED AIR IN PLACE. THE OVERALL SYNOPTIC PICTURE CONTINUES TO DISPLAY A BLOCKING TYPE PATTERN WITH A LONG WAVE RIDGE PRESENT OVER THE EASTERN PACIFIC...WITH EASTERN CONUS TROUGHING ONGOING...BEING REINFORCED BY SEVERAL FAST MOVING NORTHWEST FLOW DISTURBANCES .THE NEXT RATHER POTENT UPPER LEVEL SHORTWAVE TAKING AIM ON THE REGION...IS EVIDENT IN WATER VAPOR AND 00Z UPPER AIR ANALYSIS OVER NORTHERN BC AND ALBERTA...AS 150 KNOTS PLUS OF FLOW IS PRESENT IN THE UPPER JET CORE ASSOCIATED WITH THIS SYSTEM. TODAY...LAKE EFFECT SNOW SHOWERS WILL CONTINUE THEIR SLOW DEMISE AS INVERSION HEIGHTS FALL INTO THE DGZ/FLOW TURNS MORE SOUTHWESTERLY/AND DRY AIR CONTINUES TO INFILTRATE THE REGION UPWIND OF THE LAKE. WILL LET THE ADV RIDE...AS CONDITIONS WILL REMAIN FAVORABLE FOR ANOTHER INCH OR TWO THIS MORNING...AND GIVEN THE MORNING COMMUTE JUST AHEAD. OTHERWISE...NAM12/RUC 13 BOTH INDICATE VERY LITTLE QPF BEYOND 15Z. HAVE OPTED FOR DIMINISHING POPS IN THE AFTERNOON. LINGERING LL MOISTURE IN THE H9-H85 LAYER WILL ALLOW CU DEVELOPMENT ONCE INSOLATION OCCUR THIS MORNING...CLOUDS SHOULD MIX OUT INTO THE AFTERNOON WITH A PT SUNNY CONDITIONS POSSIBLE BY THEN. TONIGHT THROUGH SATURDAY...POTENT CLIPPER SYSTEM WILL TAKE AIM ON THE REGION. MOISTURE LOOKS TO BE LIMITED WITH THIS SYSTEM AS GULF INFLUENCES WILL BE NONEXISTENT. HOWEVER...THE BIGGEST IMPACT MAY BE THE COMBINATION OF THE 1 TO 2 INCH SNOWFALL AND GUSTY WINDS...CREATING POSSIBLE NEAR ZERO VISIBILITY CONDITIONS...ESPECIALLY SAT NIGHT WHEN CAA AND DOWNWARD MOMENTUM TRANSPORT WILL MAXIMIZED. FORECAST MODELS HAVE PUSHED UP THE ARRIVAL TIME OF THIS SYSTEM COMPARED WOT PREVIOUS RUNS...OPTING FOR A SNOW ARRIVAL BEFORE 12Z SAT. THIS IS CONFIRMED BY THE GEFS/SREF/AND NAEFS ENSEMBLE RUNS WHICH ALSO PREFER THE EARLIER TREND. POTENT ISENTROPIC LIFT NOTED ON THE 285K SFC WITH 50 KNOTS CROSS ISOBARIC FLOW UNDER TROPOPAUSE PRESSURE RISES AND RATHER STEEP MD LEVEL LAPSE RATES CONFIRM THE SETUP FOR A PERIOD OF DECENT SNOW GIVEN OMEGA MAXIMIZED IN THE DGZ. HAVE BLENDED FORECAST POPS UP IN LINE WITH MOS NUMBERS. THINGS CERTAINLY GET INTERESTING IN THE NW FA AS LAKE ENHANCEMENT OF THE SYNOPTIC SNOW WILL BE LIKELY. FORECAST MODELS PROG THE GREATEST IMPACTS FROM LAKE ENHANCEMENT OVER PORTIONS OF WEST CENTRAL MI WHERE SNOWFALL RATES COULD BE DOUBLED. NAM H925 OMEGA PLOTS DO CONFIRM THAT AS CAA ENSUES AND THE LL FLOW VEERS NW...LAKE EFFECT ENHANCEMENT COULD AFFECT PORTIONS OF THE NW FA...WITH PURE LAKE EFFECT SHOWERS/BANDING LIKELY BY EVENING...LASTING INTO THE OVERNIGHT. THIS AREA WILL NEED TO BE WATCH FOR A POTENTIAL ADV OR WATCH/WARNING WITH HEAVY SNOW AND BLOWING SNOW THE BIGGEST CONCERNS. A PERIOD OF DECENT LAKE EFFECT SNOW MAY AFFECT THE REMAINDER OF THE LAKE BELT REGION INTO SUNDAY GIVEN NNW FLOW TENDING TO FAVOR LAKE SUPERIOR AGGREGATE EFFECTS. OTHERWISE...EXPECT BELOW TEMPS THROUGHOUT THE PERIOD WITH HIGHS IN THE 20S AND LOWS IN THE TEENS TO POSSIBLE SINGLE DIGITS BY SUN MORNING. LONG TERM... ..SUNDAY THROUGH THURSDAY... THE LONG TERM PICTURE CONTINUES TO BE FRAMED IN A BELOW NORMAL TEMPERATURE PORTRAIT. NUMEROUS SHORT WAVES WILL IMPACT THE AREA OVER THE LONG TERM PERIOD AND KEEP COLDER AIR IN PLACE ALONG WITH SEVERAL CHANCES FOR SNOWFALL. SUNDAY WILL SEE NORTHWEST FLOW AND DELTA T VALUES IN LOWER 20S WHICH WILL AID IN LAKE EFFECT SNOW SHOWERS THROUGH MID AFTERNOON BEFORE HIGH PRESSURE FINALLY MOVES IN AND ENDS LAKE EFFECT. SIMILAR TO CURRENT EVENT...COULD SEE SEVERAL INCHES OF ACCUMULATION STRUNG OUT OVER SEVERAL HOURS FROM SATURDAY NIGHT INTO SUNDAY AFTERNOON. THIS WILL BE DEPENDENT ON ORIENTATION AND MOVEMENT OF BANDS. NO HEADLINES PLANNED AT THIS TIME. NEXT SYSTEM BEGINS TO TAKE SHAPE TO OUR WEST SUNDAY NIGHT AND APPROACHES MONDAY NIGHT INTO TUESDAY. WARM AIR ADVECTION BEGINS AHEAD OF THIS WAVE SUNDAY NIGHT WITH INCREASING MOISTURE AND WEAK LIFT. MAYBE SOME LIGHT SNOW OR FLURRIES INTO WESTERN AREAS LATE SUNDAY NIGHT BUT STAYED WITH WELL COLLABORATED MONDAY POPS FOR NOW. THIS APPROACHING SHORT WAVE STILL HAS MUCH UNCERTAINTY WITH EVOLUTION AND MOVEMENT. THIS WAVE APPEARS TO DEVELOP OFF THE CA COAST TODAY AND EVENTUALLY MOVES INTO PLAINS ON MONDAY. QUESTION REMAINS ON DEGREE OF PHASING WITH NORTHERN STREAM AND STRENGTH OF DEVELOPMENT. MEDIUM RANGE MODELS COMING INTO AGREEMENT ON A WEAKER SYSTEM MOVING THROUGH OUR AREA BUT THERE HAVE BEEN SOME EARLIER SOLUTIONS SHOWING A STRONGER SYSTEM. SIMILAR PATTERN LAST YEAR SAW A TROPICAL MOISTURE PLUME ASSOCIATED WITH THESE WAVES AND MODELS WERE SLOW TO CATCH ON. CURRENT WATER VAPOR SHOWS AN ESTABLISHED TROPICAL PACIFIC PLUME INTO THE BAJA AREA...SOUTH OF WHERE THIS WAVE IS EXPECTED TO DEVELOP TODAY. THIS WILL BE WATCHED CLOSELY BUT CURRENT GRIDS HAVE RAIN OR SNOW FOR TUESDAY WITH BAROCLINIC ZONE IN VICINITY OF FA. PLAN TO KEEP THIS FOR NOW AND INCREASED POPS INTO MID CHANCE CATEGORY. BELOW NORMAL CONFIDENCE EXISTS FOR TUE THROUGH THURSDAY TIME FRAME WITH EVOLUTION OF THIS WAVE AND STRONGER ENERGY DIGGING INTO PLAINS TOWARD END OF PERIOD. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 11 PM EST THIS EVENING FOR LMZ043-046. GALE WARNING FROM 11 PM THIS EVENING TO 3 AM EST SUNDAY FOR LMZ043-046. && $$ SHORT TERM...JC LONG TERM...LASHLEY AVIATION...TAYLOR in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 419 AM EST FRI DEC 5 2008 .SHORT TERM... ODAY THROUGH SATURDAY LAKE EFFECT SNOW SHOWERS CONTINUE TO IMPACT SW MI THIS MORNING...WITH DOPPLER RADAR ESTIMATIONS OF 2 TO 4 INCHES ACROSS A NARROW SWATH OF BERRIEN AND CASS COUNTIES. OTHERWISE...GENERALLY CLEAR SKIES RE PREVAILING ACROSS THE REGION WITH JUST A FEW CLOUDS AND FLURRIES ARE IN PLACE ACROSS THE FAR SOUTH WHERE A SUBTLE WIND SHIFT IS OCCURRING WITH A WEAK UPPER WAVE. TEMPS ARE GENERALLY IN THE TEENS...SAVE FOR THE FAR NW WHERE LOW 20S ARE PRESENT WITH LAKE MODIFIED AIR IN PLACE. THE OVERALL SYNOPTIC PICTURE CONTINUES TO DISPLAY A BLOCKING TYPE PATTERN WITH A LONG WAVE RIDGE PRESENT OVER THE EASTERN PACIFIC...WITH EASTERN CONUS TROUGHING ONGOING...BEING REINFORCED BY SEVERAL FAST MOVING NORTHWEST FLOW DISTURBANCES .THE NEXT RATHER POTENT UPPER LEVEL SHORTWAVE TAKING AIM ON THE REGION...IS EVIDENT IN WATER VAPOR AND 00Z UPPER AIR ANALYSIS OVER NORTHERN BC AND ALBERTA...AS 150 KNOTS PLUS OF FLOW IS PRESENT IN THE UPPER JET CORE ASSOCIATED WITH THIS SYSTEM. TODAY...LAKE EFFECT SNOW SHOWERS WILL CONTINUE THEIR SLOW DEMISE AS INVERSION HEIGHTS FALL INTO THE DGZ/FLOW TURNS MORE SOUTHWESTERLY/AND DRY AIR CONTINUES TO INFILTRATE THE REGION UPWIND OF THE LAKE. WILL LET THE ADV RIDE...AS CONDITIONS WILL REMAIN FAVORABLE FOR ANOTHER INCH OR TWO THIS MORNING...AND GIVEN THE MORNING COMMUTE JUST AHEAD. OTHERWISE...NAM12/RUC 13 BOTH INDICATE VERY LITTLE QPF BEYOND 15Z. HAVE OPTED FOR DIMINISHING POPS IN THE AFTERNOON. LINGERING LL MOISTURE IN THE H9-H85 LAYER WILL ALLOW CU DEVELOPMENT ONCE INSOLATION OCCUR THIS MORNING...CLOUDS SHOULD MIX OUT INTO THE AFTERNOON WITH A PT SUNNY CONDITIONS POSSIBLE BY THEN. TONIGHT THROUGH SATURDAY...POTENT CLIPPER SYSTEM WILL TAKE AIM ON THE REGION. MOISTURE LOOKS TO BE LIMITED WITH THIS SYSTEM AS GULF INFLUENCES WILL BE NONEXISTENT. HOWEVER...THE BIGGEST IMPACT MAY BE THE COMBINATION OF THE 1 TO 2 INCH SNOWFALL AND GUSTY WINDS...CREATING POSSIBLE NEAR ZERO VISIBILITY CONDITIONS...ESPECIALLY SAT NIGHT WHEN CAA AND DOWNWARD MOMENTUM TRANSPORT WILL MAXIMIZED. FORECAST MODELS HAVE PUSHED UP THE ARRIVAL TIME OF THIS SYSTEM COMPARED WOT PREVIOUS RUNS...OPTING FOR A SNOW ARRIVAL BEFORE 12Z SAT. THIS IS CONFIRMED BY THE GEFS/SREF/AND NAEFS ENSEMBLE RUNS WHICH ALSO PREFER THE EARLIER TREND. POTENT ISENTROPIC LIFT NOTED ON THE 285K SFC WITH 50 KNOTS CROSS ISOBARIC FLOW UNDER TROPOPAUSE PRESSURE RISES AND RATHER STEEP MD LEVEL LAPSE RATES CONFIRM THE SETUP FOR A PERIOD OF DECENT SNOW GIVEN OMEGA MAXIMIZED IN THE DGZ. HAVE BLENDED FORECAST POPS UP IN LINE WITH MOS NUMBERS. THINGS CERTAINLY GET INTERESTING IN THE NW FA AS LAKE ENHANCEMENT OF THE SYNOPTIC SNOW WILL BE LIKELY. FORECAST MODELS PROG THE GREATEST IMPACTS FROM LAKE ENHANCEMENT OVER PORTIONS OF WEST CENTRAL MI WHERE SNOWFALL RATES COULD BE DOUBLED. NAM H925 OMEGA PLOTS DO CONFIRM THAT AS CAA ENSUES AND THE LL FLOW VEERS NW...LAKE EFFECT ENHANCEMENT COULD AFFECT PORTIONS OF THE NW FA...WITH PURE LAKE EFFECT SHOWERS/BANDING LIKELY BY EVENING...LASTING INTO THE OVERNIGHT. THIS AREA WILL NEED TO BE WATCH FOR A POTENTIAL ADV OR WATCH/WARNING WITH HEAVY SNOW AND BLOWING SNOW THE BIGGEST CONCERNS. A PERIOD OF DECENT LAKE EFFECT SNOW MAY AFFECT THE REMAINDER OF THE LAKE BELT REGION INTO SUNDAY GIVEN NNW FLOW TENDING TO FAVOR LAKE SUPERIOR AGGREGATE EFFECTS. OTHERWISE...EXPECT BELOW TEMPS THROUGHOUT THE PERIOD WITH HIGHS IN THE 20S AND LOWS IN THE TEENS TO POSSIBLE SINGLE DIGITS BY SUN MORNING. && .LONG TERM... ...SUNDAY THROUGH THURSDAY... THE LONG TERM PICTURE CONTINUES TO BE FRAMED IN A BELOW NORMAL TEMPERATURE PORTRAIT. NUMEROUS SHORT WAVES WILL IMPACT THE AREA OVER THE LONG TERM PERIOD AND KEEP COLDER AIR IN PLACE ALONG WITH SEVERAL CHANCES FOR SNOWFALL. SUNDAY WILL SEE NORTHWEST FLOW AND DELTA T VALUES IN LOWER 20S WHICH WILL AID IN LAKE EFFECT SNOW SHOWERS THROUGH MID AFTERNOON BEFORE HIGH PRESSURE FINALLY MOVES IN AND ENDS LAKE EFFECT. SIMILAR TO CURRENT EVENT...COULD SEE SEVERAL INCHES OF ACCUMULATION STRUNG OUT OVER SEVERAL HOURS FROM SATURDAY NIGHT INTO SUNDAY AFTERNOON. THIS WILL BE DEPENDENT ON ORIENTATION AND MOVEMENT OF BANDS. NO HEADLINES PLANNED AT THIS TIME. NEXT SYSTEM BEGINS TO TAKE SHAPE TO OUR WEST SUNDAY NIGHT AND APPROACHES MONDAY NIGHT INTO TUESDAY. WARM AIR ADVECTION BEGINS AHEAD OF THIS WAVE SUNDAY NIGHT WITH INCREASING MOISTURE AND WEAK LIFT. MAYBE SOME LIGHT SNOW OR FLURRIES INTO WESTERN AREAS LATE SUNDAY NIGHT BUT STAYED WITH WELL COLLABORATED MONDAY POPS FOR NOW. THIS APPROACHING SHORT WAVE STILL HAS MUCH UNCERTAINTY WITH EVOLUTION AND MOVEMENT. THIS WAVE APPEARS TO DEVELOP OFF THE CA COAST TODAY AND EVENTUALLY MOVES INTO PLAINS ON MONDAY. QUESTION REMAINS ON DEGREE OF PHASING WITH NORTHERN STREAM AND STRENGTH OF DEVELOPMENT. MEDIUM RANGE MODELS COMING INTO AGREEMENT ON A WEAKER SYSTEM MOVING THROUGH OUR AREA BUT THERE HAVE BEEN SOME EARLIER SOLUTIONS SHOWING A STRONGER SYSTEM. SIMILAR PATTERN LAST YEAR SAW A TROPICAL MOISTURE PLUME ASSOCIATED WITH THESE WAVES AND MODELS WERE SLOW TO CATCH ON. CURRENT WATER VAPOR SHOWS AN ESTABLISHED TROPICAL PACIFIC PLUME INTO THE BAJA AREA...SOUTH OF WHERE THIS WAVE IS EXPECTED TO DEVELOP TODAY. THIS WILL BE WATCHED CLOSELY BUT CURRENT GRIDS HAVE RAIN OR SNOW FOR TUESDAY WITH BAROCLINIC ZONE IN VICINITY OF FA. PLAN TO KEEP THIS FOR NOW AND INCREASED POPS INTO MID CHANCE CATEGORY. BELOW NORMAL CONFIDENCE EXISTS FOR TUE THROUGH THURSDAY TIME FRAME WITH EVOLUTION OF THIS WAVE AND STRONGER ENERGY DIGGING INTO PLAINS TOWARD END OF PERIOD. && .AVIATION.../06Z TAFS/ FLIGHT RESTRICTIONS WILL BE LIMITED TO LAKE EFFECT SNOW SHOWERS ACROSS THE FAR NORTH. VARYING CIGS DOWN TO 1.5KFT AND VISBYS DOWN TO 1/2 MILE ARE POSSIBLE IN THE HEAVIER BANDS...WHICH WILL BE CONFINED TO SOUTHERN MI. SBN WILL BE ON THE EDGE OF THE ACTIVITY WITH A PERIOD OF MVFR CIGS AND VISBYS POSSIBLE EARLY THIS MORNING. OTHERWISE...SCT MVFR CIGS WILL BE POSSIBLE ACROSS THE SOUTH AND WEST...WITH A WEAK UPPER WAVE PASSING THROUGH THE REGION. WINDS WILL BACK SOUTHERLY THROUGH THE PERIOD...IN RESPONSE TO THE NEXT LOW PRESSURE SYSTEM APPROACHING THE REGION. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...LAKE EFFECT SNOW ADVISORY UNTIL NOON EST TODAY FOR MIZ077>079. OH...NONE. LM...GALE WATCH FROM SATURDAY AFTERNOON THROUGH LATE SATURDAY NIGHT FOR LMZ043-046. SMALL CRAFT ADVISORY UNTIL 1 PM EST SATURDAY FOR LMZ043-046. && $$ SHORT TERM...JC LONG TERM...LASHLEY AVIATION...JC in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1229 AM EST FRI DEC 5 2008 .AVIATION.../06Z TAFS/ FLIGHT RESTRICTIONS WILL BE LIMITED TO LAKE EFFECT SNOW SHOWERS ACROSS THE FAR NORTH. VARYING CIGS DOWN TO 1.5KFT AND VISBYS DOWN TO 1/2 MILE ARE POSSIBLE IN THE HEAVIER BANDS...WHICH WILL BE CONFINED TO SOUTHERN MI. SBN WILL BE ON THE EDGE OF THE ACTIVITY WITH A PERIOD OF MVFR CIGS AND VISBYS POSSIBLE EARLY THIS MORNING. OTHERWISE...SCT MVFR CIGS WILL BE POSSIBLE ACROSS THE SOUTH AND WEST...WITH A WEAK UPPER WAVE PASSING THROUGH THE REGION. WINDS WILL BACK SOUTHERLY THROUGH THE PERIOD...IN RESPONSE TO THE NEXT LOW PRESSURE SYSTEM APPROACHING THE REGION. && .PREV DISCUSSION... /ISSUED 1141 PM EST THU DEC 4 2008/ UPDATE... LAKE EFFECT SNOW SHOWERS ARE ONGOING ACROSS SW LOWER MI...WITH SOME INTENSE SQUALLS PRODUCING ONE INCH PER HOUR SNOW RATES PER SPOTTER REPORTS. SNOW SHOWERS HAVE INCREASED IN COVERAGE AND INTENSITY PER COOLING ALOFT PER AN ADVANCING UPPER WAVE...ALLOWING LAKE INDUCED CAPES TO RISE TO NEARLY 600 J/KG...WITH MAX UPWARD OMEGA IN THE DGZ. WITH BUFR PROGS SUPPORTING CAPES AROUND 400-600 J/KG THROUGH ABOUT NOON WITH FAVORABLE FETCH AND LL UPWIND RH OF AT LEAST 60 PERCENT...HAVE ISSUED A LAKE SNOW ADV FOR ACCUMS OF 2-4 INCHES WITH IMPACTS TO TRAVEL. INVERSION HEIGHTS WILL FALL FRIDAY MORNING...TRENDING SHOWER ACTIVITY TO JUST FLURRIES BY AFTERNOON. HAVE OPTED FOR A BLEND OF THE RUC13 AND NAM12 QPF...WHICH PLACES MAXIMUM VALUES IN CASS AND WESTERN SAINT JOSEPH /MI/...WHERE 5 INCHES MAY BE POSSIBLE BASED ON A 23:1 RATIO. OTHERWISE...JUST SOME TWEAKS TO SKY GRIDS...ALL ELSE IN GOOD SHAPE. PREV DISCUSSION... /ISSUED 343 PM EST THU DEC 4 2008/ SHORT TERM... CAA/LAKE EFFECT CLOUDINESS CONTS OVER THE GRTLKS REGION...INCLUDING NE 1/2 OF OUR CWA THIS AFTN. SOME LAKE EFFECT SNOW HAS OCCURRED MUCH OF THE DAY ACROSS MUCH OF SRN MI AND ADJACENT NRN INDIANA COUNTIES...HWVR INVERSION WHICH TAMDAR SOUNDINGS INDICATE IS BASED AROUND 3-5KFT...ALONG WITH SHORT WNW FETCH HAS LIMITED INTENSITY OF SNOW SHOWERS IN OUR AREA. COLDER AIR WILL CONTINUE TO ADVECT INTO THE REGION TONIGHT. SHRTWV SEEN ON WATER VAPOR OVER THE UPR MS VALLEY WITH A SFC REFLECTION SEEN IN SFC OBS MOVG INTO NW IL ACCOMPANIED BY A FEW FLURRIES IS EXPECTED TO MOVE EAST ACROSS OUR CWA TONIGHT PSBLY CAUSING SOME FLURRIES OUTSIDE OF LAKE EFFECT AREAS. ALSO INVERSION WILL RISE OVERNIGHT AS THE TROF MOVES THROUGH WHICH SHOULD INCREASE INTENSITY OF LAKE EFFECT SNOW SHOWERS... THOUGH CONTD SHORT FETCH WILL STILL BE LIMITING FACTOR TO SGFNT ACCUMS...WENT WITH 1-2" OVER SRN MI WITH <1" IN ADJACENT IN/OH COUNTIES. H85 TEMPS EXPECTED TO FALL TO AROUND -15C IN OUR CWA OVERNIGHT. UPSTREAM TEMPS THIS MORNING IN THIS AIRMASS IN SINGLE DIGITS/TEENS. WITH LESS SNOW COVER IN OUR AREA THAN IA/NRN IL AND PARTLY TO MOSTLY CLOUDY SKIES EXPECTED OVERNIGHT...KEPT LOWS IN THE TEENS. WITH THERMAL TROF MOVG ACROSS THE AREA ON FRIDAY...TEMPS ONLY EXPECTED TO RISE INTO THE L-M20S. SFC RIDGE WILL MOVE ACROSS THE AREA DURING THE DAY CAUSING WINDS TO BACK TO SW BRINGING LAKE EFFECT TO AN END ACROSS OUR CWA BY EVE WITH THE PSBL EXCEPTION OF NRN BERRIEN COUNTY. AMOUNT OF CLOUDS QUESTIONABLE. BOTH NAM AND GFS INDICATE H925 WILL BE SATURATED...BUT THIS LAYER WAS TOO MOIST IN MODELS TODAY...SO OPTIMISTICALLY WENT WITH PARTLY SUNNY SKIES AGAIN ACROSS SRN PORTION OF THE CWA. ANOTHER STRONG CDFNT WILL DROP SE INTO THE WRN GRTLKS FRI NIGHT. ANY REMAINING LOW CLOUDS EXPECTED TO ADVECT NE OUT OF THE AREA IN THE EVE AS SWLY LOW LEVEL FLOW INCREASES. HIGH CLOUDS WILL BE SPREADING INTO THE AREA AHD OF THE UPR TROF SO EXPECTING MOSTLY CLOUDY SKIES WITH LITTLE TEMP DROP. CONTD WITH SMALL CHC OF SNOW FOR LATE FRI NIGHT AS FRONT APPROACHES...BUT STILL APPEARS BEST CHC OF SNOW WITH THE FRONT WILL BE SATURDAY. LONG TERM...(SATURDAY THROUGH THURSDAY)... CONTINUED COLD AND ACTIVE PATTERN THROUGH THE EXTENDED PERIOD WITH QUICK CLIPPER AND LAKE EFFECT SAT NITE/SUN FOLLOWED BY ANOTHER POTENTIAL STRONG SYSTEM MOVING THROUGH THE EASTERN US MIDWEEK. EXTENDED BEGINS WITH CLIPPER SYSTEM IMPACTING NW CWA AS SFC LOW MOVES THROUGH THE UPPER GREAT LAKES. SIGNIFICANT TIMING DIFFERENCES BETWEEN SLOWER NAM/FASTER GFS BRINGING PRECIP INTO THE CWA ON SATURDAY AND HAVE SIDED WITH THE TIMING OF 09Z SREF AS A COMPROMISE. HWVR AS AN ADDNL NOD TO MODEL PERFORMANCE WITH THE PREV SYSTEM HAVE MAINTAINED EARLIER POPS INDICATED BY THE GFS AND UNDERCUT THE MODEL CONSENSUS QPF BY A MARGINAL AMOUNT AS THE 12Z GFS DECREASED QPF FROM 00Z/06Z RUNS POSSIBLY FORESHADOWING SIMILAR OUTCOME OF REALIZING LESSER AMOUNTS. NET RESULT IS LIGHT/MOD SNOW SETTLING IN SATURDAY MORNING AND EXPANDING ACROSS THE CWA WITH RELATIVELY MINOR SYNOPTIC QPF AMOUNTS. ZONE-OMEGA TECHNIQUE INDICATES SNOW RATIOS ON THE ORDER OF 15:1 TRANSLATING TO 2-3 INCH SNOW TOTALS TAPERING OFF FROM NW TOWARDS THE SE. AS SYNOPTIC FORCING WANES IN WAKE OF SFC LOW WINDS TURNING NW PRODUCE LAKE EFFECT SETUP BEGINNING AROUND 00Z SAT AND CONTINUING INTO SUNDAY. BUFR SOUNDINGS SHOW DELTA-T`S PEAKING AT 20 DEG WITH INVERSION LOCATED IN LOW END OF GROWTH ZONE AND UNIDIRECTIONAL 20KT WINDS THROUGH THE LAYER. HAVE REMAINED CONSERVATIVE WITH SNOW AMOUNTS GIVEN LOCATION OF EQL LEVELS HWVR POTENTIAL EXITS FOR MORE SIGNIFICANT SNOW WITH SMALL CHANGE IN THERMAL PROFILE FAVORING BETTER SNOW GROWTH. UPR TROF SHIFTS EASTWARD WITH FLOW RETURNING TO SOUTHERLY BY MONDAY SHUTTING DOWN ANY LEFTOVER LAKE EFFECT MECHANISM AND WARMING TEMPS BACK TO UPPER 20S AND INTO LOW 30S FOR TUESDAY. RELIEF IS POTENTIALLY SHORT LIVED HOWEVER AS MODELS CONTINUE TO SHOW STRONG MID WEEK STORM TAKING SHAPE AS SFC LOW EJECTS NE THROUGH THE EASTERN US WHILE SECOND DEEPER LOW WRAPS UP NEAR BASE OF MID LEVEL TROF ALONG GOMEX WHILE A PUSH OF ARCTIC AIR INTO THE US FOLLOWS. CONSIDERABLE SPREAD AMONG OPERATIONAL MODELS AND ENSEMBLES AS ONE WOULD EXPECT THIS FAR OUT SO HAVE NOT ATTEMPTED TO GO BEYOND THE BIG PICTURE WHICH PAINTS POPS MON-WED AND COLDER TEMPS BEHIND FRONT ON WEDNESDAY. HAVE KEPT LATE WEEK TEMPS ABOVE GUIDANCE AS GFS TENDS TO CONSISTENTLY OVERDO COLD AIR INTRUSIONS SEVERAL DAYS OUT AND ECMWF IS NOT AS AGGRESSIVE WITH ADVANCEMENT OF COLD AIR INTO THE UPPER MISSISSIPPI VALLEY. STAY TUNED. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...LAKE EFFECT SNOW ADVISORY UNTIL NOON EST TODAY FOR MIZ077>079. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST SATURDAY FOR LMZ043-046. && $$ SHORT TERM...TAYLOR LONG TERM...LUDINGTON AVIATION...JC UPDATE...JC in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 950 PM CST FRI DEC 5 2008 .UPDATE... ANOTHER ROUND OF UPDATES WERE SENT OUT AROUND 9 PM. THE MAIN CHANGES WERE TO REDUCE SNOWFALL AMOUNTS OVER SOUTHEAST IOWA AND WEST CENTRAL ILLINOIS AND TO TWEAK HOURLY TEMP TRENDS AND INCREASE WINDS TONIGHT. 00Z ANALYSIS SHOWED A SURFACE WARM FROM EXTENDING SOUTH THROUGH CENTRAL IOWA WITH THE H8 FRONT OVER EASTERN IA AND THE ARCTIC SURFACE FRONT JUST CROSSING INTO NORTH DAKOTA. SNOW RAPIDLY DEVELOPED FROM MN SE INTO NORTHEAST IA THIS EVENING IN ISENTROPIC LIFT ACROSS THE WARM FRONT. ONE BAND OF SNOW WAS MOVING THROUGH THE NORTHERN CWA AND HAS PRODUCED VSBYS AROUND 1 MILE FOR A BRIEF TIME. REGIONAL RADAR COMPOSITE WAS SHOWING ANOTHER BAND OF SNOW MOVING THROUGH NORTH CENTRAL IOWA WHICH SHOULD SPREAD OVER THE NRN CWA AROUND MIDNIGHT. CURRENT PCPN TRENDS COMBINED WITH RUC/NAM ISENTROPIC PROGS SUGGEST MOST OF THE SNOW TONIGHT WILL BE NORTH OF I80. SO AMOUNTS AND POPS WERE TRIMMED BACK SOME OVER THE SOUTHERN CWA WITH LITTLE CHANGE MADE TO PREVIOUS SNOWFALL AMOUNTS IN THE NORTH. CWA WILL ALSO BE IN THE WARM SECTOR MOST OF THE NIGHT WITH STRONG SOUTHWEST WINDS AND CLOUDS HELPING TEMPS RISE SLOWLY MOST OF THE NIGHT. ...DLF... && .AVIATION... SNOW MOVING THROUGH NRN CWFA CURRENTLY WILL PRODUCE OCCASIONAL MVFR CIGS/VSBYS WITH BRIEF IFR CONDITIONS AT KCID/KDBQ/KMLI THROUGH EARLY SATURDAY MORNING. MAINLY VFR CONDITIONS ARE EXPECTED AT KBRL OVERNIGHT. SOUTH TO SOUTHWEST WINDS WILL BE SUSTAINED AT 15 TO 20KTS WITH GUSTS IN THE 25KTS TO 30KTS RANGE MOST OF THE NIGHT. ARCTIC FRONT WILL MOVE SOUTH THROUGH ALL TAF SITES BETWEEN 12Z AND 18Z SATURDAY EXPECT STRONG NW WINDS BEHIND THE FRONT...WHICH MAY CAUSE SOME REDUCED VSBYS IN BLOWING SNOW. ALSO EXPECTING MVFR CIGS MOST OF THE DAY. ...DLF... && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ HAASE/NICHOLS ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 330 AM CST THU DEC 4 2008 .SYNOPSIS... SKIES CLEAR ATTIM WITH WEAK SFC RIDGING /SUBSIDENCE/ IN THE WAKE OF STORM. THIS ALONG WITH FRESH SNOW COVER RESULTING IN VERY COLD CONDITIONS WITH TEMPS IN THE SINGLE DIGITS AND TEENS. WEST TO SOUTHWEST WINDS 3-8 KTS COMBINED WITH TEMPS PRODUCING WIND CHILLS IN RANGE OF AROUND ZERO TO 8 BELOW. CLOUDS ARE ON THE WAY AS SATELLITE SHOWS BAND OF LOW CLOUDS PROGRESSING EASTWARD THROUGH WESTERN IA IN ADVANCE OF COLD FRONT... WHICH DENOTES LEADING EDGE OF MAIN ARCTIC SURGE WHERE H85 TEMPS DROP IN RANGE OF -13 TO -17C AND H7 TEMPS IN RANGE OF -19 TO -24C. REGIONAL RADAR SHOWS SOME FLURRIES WITH CLOUDS WITH MORE CONCENTRATED AREA OF -SN ACROSS PORTIONS OF SOUTHERN MN AHEAD OF VORT MAX IN REGION OF H85-H7 QG CONVERGENCE. ..05.. && .SHORT TERM...TODAY AND TONIGHT... ARCTIC FRONT TO ARRIVE BY AFTN WITH GUSTY/BRISK NORTHWEST WINDS. BAND OF LOW CLOUDS IN ADVANCE TO PUSH ACROSS AREA THIS MORNING WITH STRATOCU DEVELOPING WITH ANY BREAKS AS COLD POOL MOVES IN... RESULTING IN SKIES GENERALLY BECOMING PTCLDY/MOCLDY... WITH SOME FLURRIES. WATCHING AREA OF -SN OVER SOUTHERN MN WITH VORT MAX AND LOW/MID LEVEL QG CONVERGENCE. LATEST RUC EXPANDS QG CONVERGENCE IN H85-H7 LAYER SOUTHEAST ACROSS NORTHERN SECTIONS THIS MORNING THEN SHUNTS IT TO THE EAST AS AFTN PROGRESSES WITH VORT MAX PASSING TO THE NORTH. HAVE OPTED TO ADD SLIGHT CHC POPS NORTH OF I 80 TO ACCOUNT FOR POTENTIAL FOR FEW POCKETS OF -SN/SHSN WITH ASCENT AND COMBINATION OF HEATING AND STEEPENING LOW/MID LEVEL LAPSE RATES. TEMPS SHOULD UNDERACHIEVE TODAY WITH ARRIVAL OF MAIN ARCTIC SURGE...FRESH SNOW COVER AND CLOUDS... THUS PREVIOUS FCST LOOKS ON TRACK WITH GENERAL RANGE OF 20-25 DEGS ON MAXES. WOULDN/T BE AT ALL SURPRISED TO SEE TEMPS SLIP BACK A FEW DEGS BY AFTN NORTHWEST SECTIONS. TONIGHT...CYCLONIC FLOW SHOULD KEEP CLOUDS AROUND THROUGH THE EVE WITH PTCLDY TO AREAS OF MOCLDY. THEN AT LEAST PARTIAL CLEARING EXPECTED OVRNGT AS BROAD/WEAK SFC RIDGING BUILDS IN. SETUP LOOKS SIMILAR TO THIS MORNING THUS BANKING ON ENOUGH WIND OF 3-7 KTS TO PREVENT SUB ZERO READINGS... BUT ONCE AGAIN WIDESPREAD SINGLE DIGITS WITH FEW TEENS AND SIDED CLOSE TO LOW SIDE OF GUIDANCE. ..05.. .LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY... MEDIUM RANGE MODELS...PARTICULARLY THE 00Z RUN ECMWF...DGEX AND GFS AGREE ON NORTHWEST FLOW TO LEE OF WEST COAST REX TYPE BLOCK TO EVENTUALLY DUMP A RIDGE-RIDING WAVE CLIPPER-STYLE DOWN ACRS THE WESTERN GRT LKS LATE FRI NIGHT INTO SAT...WITH STILL SOME VARIATION IN EXTENT OF SOUTHWARD DIGGING AND STRENGTH. WAA AHEAD OF THIS FEATURE TO BE REALIZED MAINLY ALOFT...WITH SFC TEMPS ON FRI ONLY RECOVERING INTO THE LOW TO MID 20S FOR HIGHS. IMPRESSIVE NOCTURNAL LLJ OF 50 KTS REALLY WAA/S FRI NIGHT AHEAD OF INCOMING CLIPPER... WITH SFC TEMPS PROBABLY SHOWING A STEADY OR SLOW RISE PHENOMENA EVEN OVER A SNOW PACK AND INCOMING SWATH OF SNOW. TAKING A BLEND OF THE FORCING AND 1000-H5 MB SATURATION OF THE 00Z GFS AND NEW ECMWF...AS WELL AS THERMAL PROFILES AND EXPECTED LSR/S...IT STILL APPEARS/CURRENT INDICATIONS SUGGEST THAT AT LEAST THE NORTHEAST HALF OF THE DVN CWA TO RECEIVE FROM 1 TO 3 INCHES ON SNOW MAINLY FROM 06Z-15Z SAT. CONTINUED WAA INTO EARLY SAT MAY HELP HIGHS REACH NEAR FREEZING BY LATE MORNING...BEFORE THE BOTTOM DROPS OUT AGAIN POST-FRONTALLY SAT AFTERNOON AND NIGHT. IN-BUILDING RIDGE WITH FRESH SNOW COVER MAY ALLOW SFC TEMPS TO DIP TO THE LOW SINGLE DIGITS BY SUNDAY MORNING. NEXT WEEK...MEDIUM RANGE MODELS AND ENSEMBLES CONTINUE TO ADVERTISE AN ACTIVE PATTERN WITH WAVE ENERGY PROPAGATING INLAND POSSIBLY IN A EVOLVING SPLIT FLOW REGIME...AND THEN PHASE INTO ANOTHER BROAD SCALE L/W TROF ACRS THE MID CONUS AND GRT LKS BY NEXT WED. THE ECMWF MAY BE IMPACTED BY SMALLER SCALE NUISANCE TYPE SYSTEMS...WITH THE MORE ORGANIZED LARGE SCALE STORM SYSTEMS LIFTING OUT TO THE SOUTH AND SOUTHEAST OF THE LOCAL FCST AREA/DEPENDING OF COURSE ON THE EXTENT OF PHASING/ AND EVENTUALLY TURNING INTO A NORTHEASTER. INTERESTING THE EXTENT OF COLD THAT THE NEW 00Z GFS ADVERTISES DUMPING DOWN ACRS THE CWA BY NEXT WED TO WEST OF A SOUTHERLY ORIENTED POLAR VORTEX OVER LK MICHIGAN...A -30 C H85 MB POOL. IF THIS WHERE TO OCCUR IT WOULD SUPPORT RECORD OR NEAR RECORD TEMPERATURES. BUT THIS DIFFERS GREATLY FROM THE 00Z ECMWF WHICH IS ACTUALLY IN A WAA REGIME ACRS THE LOCAL AREA ON WED AHEAD OF A STRONG NORTHERN STREAM WAVE DIGGING ACRS THE NORTHERN PLAINS/UPPER MIDWEST. SO NEEDLESS TO SAY THERE IS GREAT UNCERTAINTY IN THE LONG RANGE FOR NEXT WEEK AND WILL NOT MAKE ANY CHANGES FOR MONDAY ON. ..12.. && .AVIATION... SFC COLD FRONT DENOTING MAIN SURGE OF ARCTIC AIR TO SWEEP ACROSS THE REGION LATER THIS MORNING INTO EARLY AFTN WITH WINDS BECOMING NORTHWEST WITH SOME GUSTS OF 18-22 KTS AS LOW/MID LEVEL LAPSE RATES STEEPEN. BAND OF CLOUDS IN HIGH MVFR TO LOW VFR RANGE IN ADVANCE OF SFC FRONT TO MOVE ACROSS TERMINALS BETWEEN 09Z-13Z. ANY BREAKS OR CLEARING TO FILL IN WITH COLD AIR STRATOCU WITH CIGS MVFR TO VFR RANGE THROUGH AFTN WITH SOME FLURRIES. UPPER LEVEL DISTURBANCE OVER THE UPPER MIDWEST WILL DIVE E/SE WITH LOW POTENTIAL FOR BRIEF PERIOD OF -SN WITH 3-5 MI VSBYS IMPACTING KDBQ TERMINAL 14Z-18Z TIMEFRAME. VFR CIGS WITH AT LEAST PARTIAL CLEARING EXPECTED TNGT AS WEAK SFC RIDGE BUILDS IN. WINDS TO BACK TO THE WEST AND SOUTHWEST AT 3-7 KTS. ..05.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ 05/12 ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 132 PM EST THU DEC 4 2008 .SHORT TERM.../THE REST OF TODAY/ REMOVED MORNING AND AFTERNOON WORDING FROM ZONE FORECAST TEXT PRODUCT. HOURLY OBS INDICATE THAT TEMPERATURES ACROSS THE AREA ARE FALLING A BIT MORE SLOWLY THAN PREVIOUSLY FORECAST...BUT OVERALL THINGS ARE STILL ON TRACK FOR TEMPS TO FALL INTO AND REMAIN IN THE LOWER AND MID 30S THIS AFTERNOON. A PRETTY GOOD SNOW SHOWER WAS ONGOING AT AFD ISSUANCE AT JKL...WITH HIGHER REFLECTIVITIES SHOWING UP ON RADAR SOUTH OF THE WEATHER OFFICE. THESE HIGHER REFLECTIVITIES ARE LIKELY LARGE WET SNOW FLAKES. CONTINUED WITH MENTION OF RAIN AND SNOW MIX IN THE FORECAST FOR THE REST OF TODAY...WITH A GENERAL 30-50 PERCENT CHANCE OF PRECIPITATION ACROSS THE BOARD. LATEST RADAR LOOP INDICATES THAT NEW PRECIPITATION AREAS ARE FORMING BEHIND THE DEPARTING COLD FRONT...BUT THIS NEW ACTIVITY IS NOT AS WIDESPREAD AS THE PREVIOUS FORECAST HAD INDICATED. MADE ADJUSTMENTS TO HOURLY TEMP AND DEWPOINT GRIDS BASED ON TRENDS OBSERVED IN THIS MORNINGS SURFACE OBS. THE REST OF THE FORECAST IS IN GOOD SHAPE. UPDATE ZONES HAVE ALREADY BEEN ISSUED. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TONIGHT THROUGH SATURDAY/ TEMPERATURES ARE EXPECTED TO FALL AFTER FROPA...DROPPING INTO THE LOWER TO MID 30S DURING THE AFTERNOON. THE PRECIP MAY MIX WITH OR CHANGE OVER TO SNOW BRIEFLY BEFORE ENDING. THE RAIN/SNOW CHANGEOVER LINE SEEMS TO BE LINING UP WELL WITH THE 1304 H10-H8 THICKNESS LINE ON THE RUC. IN THE PAST FEW HOURS...THE POST FRONTAL PRECIP HAS BEEN DIMINISHING...WITH NOT MANY STATIONS TO OUR WEST REPORTING SNOW ATTM. NO SNOW ACCUMULATION IS EXPECTED...ALTHOUGH AN ISOLATED SPOT ABOVE 2500 FEET NEAT THE VIRGINIA BORDER MAY SEE UP TO A HALF INCH OR SO. PRECIP SHOULD TAPER OFF FROM WEST TO EAST DURING THE DAY. THERE WILL BE SOME UPSLOPE FLOW BY AFTERNOON...WHICH COULD HELP A FEW MORE AREAS OF LIGHT RAIN AND SNOW TO LINGER IN THE SOUTHEASTERN CWA INTO LATE AFTERNOON. DRY AIR RAPIDLY MOVES IN BY EVENING...AND THIS SHOULD HELP CUT OFF ANY PRECIP. HIGH PRESSURE ALSO BUILDS IN TONIGHT. WITH PARTLY CLOUDY SKIES...OVERNIGHT LOWS SHOULD GENERALLY DROP INTO THE LOWER 20S. THE SURFACE HIGH REMAINS IN CONTROL ON FRIDAY...ALTHOUGH SOME MID AND HIGH CLOUDS SHOULD PASS OVER THE REGION AS A WEAK H5 TROF SWINGS THROUGH. CAN/T RULE OUT A FLURRY...BUT WILL NOT INCLUDE IN THE FORECAST ATTM. SHOULD BE RATHER COLD WITH HIGHS IN THE LOWER 30S IN THE NORTH TO THE UPPER 30S IN THE SOUTH. MANY VALLEY AREAS WILL LIKELY SEE TEMPS DROP INTO THE TEENS FRIDAY NIGHT. ON SATURDAY THE NEXT CLIPPER SYSTEM APPROACHES IN THE AFTERNOON. WILL KEEP SLIGHT CHANCE TO CHANCE POPS ACROSS THE AREA FOR SNOW SHOWERS. ANY SNOW COULD BE MIXED WITH SOME RAIN IF THE BOUNDARY LAYER WARMS ENOUGH. DID UNDERCUT GUIDANCE SOME FOR SATURDAY...CONSIDERING A COLD START AND INCREASING CLOUD COVER. .LONG TERM.../SATURDAY NIGHT THROUGH WEDNESDAY/ A STRONG SHORT WAVE WILL DROP SOUTHEAST ACROSS THE AREA SATURDAY NIGHT...WITH UPSLOPE FLOW DEVELOPING OVERNIGHT. THIS SHOULD RESULT IN AN INCREASE IN SNOW SHOWERS THROUGH THE NIGHT. COLUMN WILL COOL QUICKLY SUPPORTING ALL SNOW OVERNIGHT WITH SOME LIGHT ACCUMULATIONS POSSIBLE IN THE FAVORED HIGHER TERRAIN OF SOUTHEAST KENTUCKY. ANY SNOW SHOWER ACTIVITY SHOULD TAPER OFF QUICKLY SUNDAY MORNING AS THE UPPER TROUGH SHIFTS EAST AWAY FROM THE REGION AND HIGH PRESSURE BUILDS IN AT THE SURFACE. DROPPED TEMPS A FEW DEGREES ON SUNDAY WITH PROGGED 850 MB AIRMASS OVERHEAD LIKELY ONLY SUPPORTING MID 30S AT BEST. HIGH PRESSURE WITH RISING HEIGHTS ALOFT SHOULD SUPPORT A MODEST WARM UP ON MONDAY WITH TEMPS WARMING INTO THE LOW TO MID 40S. MODELS THEN INDICATE A SHORTWAVE WILL DIVE SOUTHEAST THROUGH THE PLAINS SUPPORTING CYCLOGENESIS TO OUR WEST MONDAY NIGHT. IT APPEARS LIKE THE BEST TIME FRAME FOR PRECIP ACROSS THE AREA IS ON TUESDAY INTO TUESDAY NIGHT BASED LARGELY ON THE 03/12Z GFS AND NCEP ENSEMBLE. 03/12Z ECMWF IS MUCH QUICKER WITH THE SYSTEM MOVING ANY PRECIP OUT QUICKLY TUESDAY NIGHT. WILL CONTINUE WITH CHANCE POPS ONLY TUESDAY THROUGH WEDNESDAY DUE TO THE UNCERTAINTY AND MENTION ONLY RAIN UNTIL TUESDAY NIGHT WHEN THERE IS SUPPORT FOR A POSSIBLE RAIN/SNOW CHANGEOVER WITH RAIN AND SNOW MIX POSSIBLE THROUGH THE DAY ON WEDNESDAY. && .AVIATION.../18Z TO 18Z/...UPDATED A COLD FRONT HAS PUSHED SE OF THE AREA...WITH LIGHT TO MODERATE SNOW AND RAIN SHOWERS BEHIND THE FRONT AS AN UPPER LEVEL DISTURBANCE PASSES BY. CLOUDS ARE IN THE IFR TO MVFR RANGE BEHIND THE BOUNDARY...AND EXPECT THE LOW CLOUDS TO GRADUALLY CLEAR OUT FROM WEST TO EAST BETWEEN 19Z AND 2Z...WITH CONDITIONS BECOMING VFR ONCE THE LOW CLOUDS CLEAR OUT. VFR SHOULD THEN REMAIN THROUGH THE END OF THE PERIOD AS HIGH PRESSURE BUILDS INTO THE AREA. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...WJM/AR LONG TERM....ABE AVIATION...JP ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1107 AM EST THU DEC 4 2008 .SHORT TERM.../THE REST OF TODAY/...UPDATED REMOVED MORNING AND AFTERNOON WORDING FROM ZONE FORECAST TEXT PRODUCT. HOURLY OBS INDICATE THAT TEMPERATURES ACROSS THE AREA ARE FALLING A BIT MORE SLOWLY THAN PREVIOUSLY FORECAST...BUT OVERALL THINGS ARE STILL ON TRACK FOR TEMPS TO FALL INTO AND REMAIN IN THE LOWER AND MID 30S THIS AFTERNOON. A PRETTY GOOD SNOW SHOWER WAS ONGOING AT AFD ISSUANCE AT JKL...WITH HIGHER REFLECTIVITIES SHOWING UP ON RADAR SOUTH OF THE WEATHER OFFICE. THESE HIGHER REFLECTIVITIES ARE LIKELY LARGE WET SNOW FLAKES. CONTINUED WITH MENTION OF RAIN AND SNOW MIX IN THE FORECAST FOR THE REST OF TODAY...WITH A GENERAL 30-50 PERCENT CHANCE OF PRECIPITATION ACROSS THE BOARD. LATEST RADAR LOOP INDICATES THAT NEW PRECIPITATION AREAS ARE FORMING BEHIND THE DEPARTING COLD FRONT...BUT THIS NEW ACTIVITY IS NOT AS WIDESPREAD AS THE PREVIOUS FORECAST HAD INDICATED. MADE ADJUSTMENTS TO HOURLY TEMP AND DEWPOINT GRIDS BASED ON TRENDS OBSERVED IN THIS MORNINGS SURFACE OBS. THE REST OF THE FORECAST IS IN GOOD SHAPE. UPDATE ZONES HAVE ALREADY BEEN ISSUED. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TONIGHT THROUGH SATURDAY/ TEMPERATURES ARE EXPECTED TO FALL AFTER FROPA...DROPPING INTO THE LOWER TO MID 30S DURING THE AFTERNOON. THE PRECIP MAY MIX WITH OR CHANGE OVER TO SNOW BRIEFLY BEFORE ENDING. THE RAIN/SNOW CHANGEOVER LINE SEEMS TO BE LINING UP WELL WITH THE 1304 H10-H8 THICKNESS LINE ON THE RUC. IN THE PAST FEW HOURS...THE POST FRONTAL PRECIP HAS BEEN DIMINISHING...WITH NOT MANY STATIONS TO OUR WEST REPORTING SNOW ATTM. NO SNOW ACCUMULATION IS EXPECTED...ALTHOUGH AN ISOLATED SPOT ABOVE 2500 FEET NEAT THE VIRGINIA BORDER MAY SEE UP TO A HALF INCH OR SO. PRECIP SHOULD TAPER OFF FROM WEST TO EAST DURING THE DAY. THERE WILL BE SOME UPSLOPE FLOW BY AFTERNOON...WHICH COULD HELP A FEW MORE AREAS OF LIGHT RAIN AND SNOW TO LINGER IN THE SOUTHEASTERN CWA INTO LATE AFTERNOON. DRY AIR RAPIDLY MOVES IN BY EVENING...AND THIS SHOULD HELP CUT OFF ANY PRECIP. HIGH PRESSURE ALSO BUILDS IN TONIGHT. WITH PARTLY CLOUDY SKIES...OVERNIGHT LOWS SHOULD GENERALLY DROP INTO THE LOWER 20S. THE SURFACE HIGH REMAINS IN CONTROL ON FRIDAY...ALTHOUGH SOME MID AND HIGH CLOUDS SHOULD PASS OVER THE REGION AS A WEAK H5 TROF SWINGS THROUGH. CAN/T RULE OUT A FLURRY...BUT WILL NOT INCLUDE IN THE FORECAST ATTM. SHOULD BE RATHER COLD WITH HIGHS IN THE LOWER 30S IN THE NORTH TO THE UPPER 30S IN THE SOUTH. MANY VALLEY AREAS WILL LIKELY SEE TEMPS DROP INTO THE TEENS FRIDAY NIGHT. ON SATURDAY THE NEXT CLIPPER SYSTEM APPROACHES IN THE AFTERNOON. WILL KEEP SLIGHT CHANCE TO CHANCE POPS ACROSS THE AREA FOR SNOW SHOWERS. ANY SNOW COULD BE MIXED WITH SOME RAIN IF THE BOUNDARY LAYER WARMS ENOUGH. DID UNDERCUT GUIDANCE SOME FOR SATURDAY...CONSIDERING A COLD START AND INCREASING CLOUD COVER. .LONG TERM.../SATURDAY NIGHT THROUGH WEDNESDAY/ A STRONG SHORT WAVE WILL DROP SOUTHEAST ACROSS THE AREA SATURDAY NIGHT...WITH UPSLOPE FLOW DEVELOPING OVERNIGHT. THIS SHOULD RESULT IN AN INCREASE IN SNOW SHOWERS THROUGH THE NIGHT. COLUMN WILL COOL QUICKLY SUPPORTING ALL SNOW OVERNIGHT WITH SOME LIGHT ACCUMULATIONS POSSIBLE IN THE FAVORED HIGHER TERRAIN OF SOUTHEAST KENTUCKY. ANY SNOW SHOWER ACTIVITY SHOULD TAPER OFF QUICKLY SUNDAY MORNING AS THE UPPER TROUGH SHIFTS EAST AWAY FROM THE REGION AND HIGH PRESSURE BUILDS IN AT THE SURFACE. DROPPED TEMPS A FEW DEGREES ON SUNDAY WITH PROGGED 850 MB AIRMASS OVERHEAD LIKELY ONLY SUPPORTING MID 30S AT BEST. HIGH PRESSURE WITH RISING HEIGHTS ALOFT SHOULD SUPPORT A MODEST WARM UP ON MONDAY WITH TEMPS WARMING INTO THE LOW TO MID 40S. MODELS THEN INDICATE A SHORTWAVE WILL DIVE SOUTHEAST THROUGH THE PLAINS SUPPORTING CYCLOGENESIS TO OUR WEST MONDAY NIGHT. IT APPEARS LIKE THE BEST TIME FRAME FOR PRECIP ACROSS THE AREA IS ON TUESDAY INTO TUESDAY NIGHT BASED LARGELY ON THE 03/12Z GFS AND NCEP ENSEMBLE. 03/12Z ECMWF IS MUCH QUICKER WITH THE SYSTEM MOVING ANY PRECIP OUT QUICKLY TUESDAY NIGHT. WILL CONTINUE WITH CHANCE POPS ONLY TUESDAY THROUGH WEDNESDAY DUE TO THE UNCERTAINTY AND MENTION ONLY RAIN UNTIL TUESDAY NIGHT WHEN THERE IS SUPPORT FOR A POSSIBLE RAIN/SNOW CHANGEOVER WITH RAIN AND SNOW MIX POSSIBLE THROUGH THE DAY ON WEDNESDAY. && .AVIATION.../12Z TO 12Z/ A COLD FRONT WILL MOVE THROUGH THE FORECAST AREA FROM NW TO SE BY 14Z. RAIN AND MVFR CONDITIONS WILL OCCUR ALONG AND BEHIND THE FRONT. PRECIPITATION WILL END FROM NW TO SE BETWEEN 14Z AND 19Z. BEFORE PRECIPITATION ENDS...RAIN MAY BRIEFLY MIX WITH OR CHANGE TO SNOW. CONDITIONS WILL IMPROVE TO VFR SHORTLY AFTER PRECIPITATION ENDS. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...WJM/AR LONG TERM....ABE AVIATION...HAL ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 658 AM EST THU DEC 4 2008 .SHORT TERM.../TODAY THROUGH SATURDAY/ AT 3 AM A COLD FRONT STRETCHED FROM SOUTHERN ONTARIO THROUGH OHIO TO WEST OF LEX...TO BNA. THIS FRONT WILL CONTINUE EAST THIS MORNING...SPREADING RAIN OVER THE AREA. GOOD LOW LEVEL JET AND UPPER DYNAMICS IN PLACE AS WELL. BY THE START OF THIS FORECAST PERIOD...12Z...THE FRONT SHOULD BE ROUGHLY FROM NEAR MOREHEAD TO LONDON. WILL MENTION 100 POPS FROM THE FRONT AND POINTS EAST...BUT WILL KEEP LIKELY TO CATEGORICAL WEST OF THE FRONT EARLY THIS MORNING FOR POST FRONTAL PRECIP. HIGH TEMPERATURES WILL BE TOUGH WITH FRONT CROSSING THROUGH THE AREA AT 12Z. WILL GENERALLY HAVE UPPER 30S TO MID 40S FROM WEST TO EAST. TEMPERATURES ARE EXPECTED TO FALL AFTER FROPA...DROPPING INTO THE LOWER TO MID 30S DURING THE AFTERNOON. THE PRECIP MAY MIX WITH OR CHANGE OVER TO SNOW BRIEFLY BEFORE ENDING. THE RAIN/SNOW CHANGEOVER LINE SEEMS TO BE LINING UP WELL WITH THE 1304 H10-H8 THICKNESS LINE ON THE RUC. IN THE PAST FEW HOURS...THE POST FRONTAL PRECIP HAS BEEN DIMINISHING...WITH NOT MANY STATIONS TO OUR WEST REPORTING SNOW ATTM. NO SNOW ACCUMULATION IS EXPECTED...ALTHOUGH AN ISOLATED SPOT ABOVE 2500 FEET NEAT THE VIRGINIA BORDER MAY SEE UP TO A HALF INCH OR SO. PRECIP SHOULD TAPER OFF FROM WEST TO EAST DURING THE DAY. THERE WILL BE SOME UPSLOPE FLOW BY AFTERNOON...WHICH COULD HELP A FEW MORE AREAS OF LIGHT RAIN AND SNOW TO LINGER IN THE SOUTHEASTERN CWA INTO LATE AFTERNOON. DRY AIR RAPIDLY MOVES IN BY EVENING...AND THIS SHOULD HELP CUT OFF ANY PRECIP. HIGH PRESSURE ALSO BUILDS IN TONIGHT. WITH PARTLY CLOUDY SKIES...OVERNIGHT LOWS SHOULD GENERALLY DROP INTO THE LOWER 20S. THE SURFACE HIGH REMAINS IN CONTROL ON FRIDAY...ALTHOUGH SOME MID AND HIGH CLOUDS SHOULD PASS OVER THE REGION AS A WEAK H5 TROF SWINGS THROUGH. CAN/T RULE OUT A FLURRY...BUT WILL NOT INCLUDE IN THE FORECAST ATTM. SHOULD BE RATHER COLD WITH HIGHS IN THE LOWER 30S IN THE NORTH TO THE UPPER 30S IN THE SOUTH. MANY VALLEY AREAS WILL LIKELY SEE TEMPS DROP INTO THE TEENS FRIDAY NIGHT. ON SATURDAY THE NEXT CLIPPER SYSTEM APPROACHES IN THE AFTERNOON. WILL KEEP SLIGHT CHANCE TO CHANCE POPS ACROSS THE AREA FOR SNOW SHOWERS. ANY SNOW COULD BE MIXED WITH SOME RAIN IF THE BOUNDARY LAYER WARMS ENOUGH. DID UNDERCUT GUIDANCE SOME FOR SATURDAY...CONSIDERING A COLD START AND INCREASING CLOUD COVER. .LONG TERM.../SATURDAY NIGHT THROUGH WEDNESDAY/ A STRONG SHORT WAVE WILL DROP SOUTHEAST ACROSS THE AREA SATURDAY NIGHT...WITH UPSLOPE FLOW DEVELOPING OVERNIGHT. THIS SHOULD RESULT IN AN INCREASE IN SNOW SHOWERS THROUGH THE NIGHT. COLUMN WILL COOL QUICKLY SUPPORTING ALL SNOW OVERNIGHT WITH SOME LIGHT ACCUMULATIONS POSSIBLE IN THE FAVORED HIGHER TERRAIN OF SOUTHEAST KENTUCKY. ANY SNOW SHOWER ACTIVITY SHOULD TAPER OFF QUICKLY SUNDAY MORNING AS THE UPPER TROUGH SHIFTS EAST AWAY FROM THE REGION AND HIGH PRESSURE BUILDS IN AT THE SURFACE. DROPPED TEMPS A FEW DEGREES ON SUNDAY WITH PROGGED 850 MB AIRMASS OVERHEAD LIKELY ONLY SUPPORTING MID 30S AT BEST. HIGH PRESSURE WITH RISING HEIGHTS ALOFT SHOULD SUPPORT A MODEST WARM UP ON MONDAY WITH TEMPS WARMING INTO THE LOW TO MID 40S. MODELS THEN INDICATE A SHORTWAVE WILL DIVE SOUTHEAST THROUGH THE PLAINS SUPPORTING CYCLOGENESIS TO OUR WEST MONDAY NIGHT. IT APPEARS LIKE THE BEST TIME FRAME FOR PRECIP ACROSS THE AREA IS ON TUESDAY INTO TUESDAY NIGHT BASED LARGELY ON THE 03/12Z GFS AND NCEP ENSEMBLE. 03/12Z ECMWF IS MUCH QUICKER WITH THE SYSTEM MOVING ANY PRECIP OUT QUICKLY TUESDAY NIGHT. WILL CONTINUE WITH CHANCE POPS ONLY TUESDAY THROUGH WEDNESDAY DUE TO THE UNCERTAINTY AND MENTION ONLY RAIN UNTIL TUESDAY NIGHT WHEN THERE IS SUPPORT FOR A POSSIBLE RAIN/SNOW CHANGEOVER WITH RAIN AND SNOW MIX POSSIBLE THROUGH THE DAY ON WEDNESDAY. && .AVIATION.../12Z TO 12Z/...UPDATED A COLD FRONT WILL MOVE THROUGH THE FORECAST AREA FROM NW TO SE BY 14Z. RAIN AND MVFR CONDITIONS WILL OCCUR ALONG AND BEHIND THE FRONT. PRECIPITATION WILL END FROM NW TO SE BETWEEN 14Z AND 19Z. BEFORE PRECIPITATION ENDS...RAIN MAY BRIEFLY MIX WITH OR CHANGE TO SNOW. CONDITIONS WILL IMPROVE TO VFR SHORTLY AFTER PRECIPITATION ENDS. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...WJM LONG TERM....ABE AVIATION...HAL ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 324 AM EST THU DEC 4 2008 .SHORT TERM.../TODAY THROUGH SATURDAY/...UPDATED AT 3 AM A COLD FRONT STRETCHED FROM SOUTHERN ONTARIO THROUGH OHIO TO WEST OF LEX...TO BNA. THIS FRONT WILL CONTINUE EAST THIS MORNING...SPREADING RAIN OVER THE AREA. GOOD LOW LEVEL JET AND UPPER DYNAMICS IN PLACE AS WELL. BY THE START OF THIS FORECAST PERIOD...12Z...THE FRONT SHOULD BE ROUGHLY FROM NEAR MOREHEAD TO LONDON. WILL MENTION 100 POPS FROM THE FRONT AND POINTS EAST...BUT WILL KEEP LIKELY TO CATEGORICAL WEST OF THE FRONT EARLY THIS MORNING FOR POST FRONTAL PRECIP. HIGH TEMPERATURES WILL BE TOUGH WITH FRONT CROSSING THROUGH THE AREA AT 12Z. WILL GENERALLY HAVE UPPER 30S TO MID 40S FROM WEST TO EAST. TEMPERATURES ARE EXPECTED TO FALL AFTER FROPA...DROPPING INTO THE LOWER TO MID 30S DURING THE AFTERNOON. THE PRECIP MAY MIX WITH OR CHANGE OVER TO SNOW BRIEFLY BEFORE ENDING. THE RAIN/SNOW CHANGEOVER LINE SEEMS TO BE LINING UP WELL WITH THE 1304 H10-H8 THICKNESS LINE ON THE RUC. IN THE PAST FEW HOURS...THE POST FRONTAL PRECIP HAS BEEN DIMINISHING...WITH NOT MANY STATIONS TO OUR WEST REPORTING SNOW ATTM. NO SNOW ACCUMULATION IS EXPECTED...ALTHOUGH AN ISOLATED SPOT ABOVE 2500 FEET NEAT THE VIRGINIA BORDER MAY SEE UP TO A HALF INCH OR SO. PRECIP SHOULD TAPER OFF FROM WEST TO EAST DURING THE DAY. THERE WILL BE SOME UPSLOPE FLOW BY AFTERNOON...WHICH COULD HELP A FEW MORE AREAS OF LIGHT RAIN AND SNOW TO LINGER IN THE SOUTHEASTERN CWA INTO LATE AFTERNOON. DRY AIR RAPIDLY MOVES IN BY EVENING...AND THIS SHOULD HELP CUT OFF ANY PRECIP. HIGH PRESSURE ALSO BUILDS IN TONIGHT. WITH PARTLY CLOUDY SKIES...OVERNIGHT LOWS SHOULD GENERALLY DROP INTO THE LOWER 20S. THE SURFACE HIGH REMAINS IN CONTROL ON FRIDAY...ALTHOUGH SOME MID AND HIGH CLOUDS SHOULD PASS OVER THE REGION AS A WEAK H5 TROF SWINGS THROUGH. CAN/T RULE OUT A FLURRY...BUT WILL NOT INCLUDE IN THE FORECAST ATTM. SHOULD BE RATHER COLD WITH HIGHS IN THE LOWER 30S IN THE NORTH TO THE UPPER 30S IN THE SOUTH. MANY VALLEY AREAS WILL LIKELY SEE TEMPS DROP INTO THE TEENS FRIDAY NIGHT. ON SATURDAY THE NEXT CLIPPER SYSTEM APPROACHES IN THE AFTERNOON. WILL KEEP SLIGHT CHANCE TO CHANCE POPS ACROSS THE AREA FOR SNOW SHOWERS. ANY SNOW COULD BE MIXED WITH SOME RAIN IF THE BOUNDARY LAYER WARMS ENOUGH. DID UNDERCUT GUIDANCE SOME FOR SATURDAY...CONSIDERING A COLD START AND INCREASING CLOUD COVER. .LONG TERM.../SATURDAY NIGHT THROUGH WEDNESDAY/ A STRONG SHORT WAVE WILL DROP SOUTHEAST ACROSS THE AREA SATURDAY NIGHT...WITH UPSLOPE FLOW DEVELOPING OVERNIGHT. THIS SHOULD RESULT IN AN INCREASE IN SNOW SHOWERS THROUGH THE NIGHT. COLUMN WILL COOL QUICKLY SUPPORTING ALL SNOW OVERNIGHT WITH SOME LIGHT ACCUMULATIONS POSSIBLE IN THE FAVORED HIGHER TERRAIN OF SOUTHEAST KENTUCKY. ANY SNOW SHOWER ACTIVITY SHOULD TAPER OFF QUICKLY SUNDAY MORNING AS THE UPPER TROUGH SHIFTS EAST AWAY FROM THE REGION AND HIGH PRESSURE BUILDS IN AT THE SURFACE. DROPPED TEMPS A FEW DEGREES ON SUNDAY WITH PROGGED 850 MB AIRMASS OVERHEAD LIKELY ONLY SUPPORTING MID 30S AT BEST. HIGH PRESSURE WITH RISING HEIGHTS ALOFT SHOULD SUPPORT A MODEST WARM UP ON MONDAY WITH TEMPS WARMING INTO THE LOW TO MID 40S. MODELS THEN INDICATE A SHORTWAVE WILL DIVE SOUTHEAST THROUGH THE PLAINS SUPPORTING CYCLOGENESIS TO OUR WEST MONDAY NIGHT. IT APPEARS LIKE THE BEST TIME FRAME FOR PRECIP ACROSS THE AREA IS ON TUESDAY INTO TUESDAY NIGHT BASED LARGELY ON THE 03/12Z GFS AND NCEP ENSEMBLE. 03/12Z ECMWF IS MUCH QUICKER WITH THE SYSTEM MOVING ANY PRECIP OUT QUICKLY TUESDAY NIGHT. WILL CONTINUE WITH CHANCE POPS ONLY TUESDAY THROUGH WEDNESDAY DUE TO THE UNCERTAINTY AND MENTION ONLY RAIN UNTIL TUESDAY NIGHT WHEN THERE IS SUPPORT FOR A POSSIBLE RAIN/SNOW CHANGEOVER WITH RAIN AND SNOW MIX POSSIBLE THROUGH THE DAY ON WEDNESDAY. && .AVIATION.../06Z TO 06Z/ A COLD FRONT WILL MOVE THROUGH THE FORECAST AREA FROM NW TO SE BETWEEN 08Z AND 14Z. A LOW LEVEL JET WILL BRING STRONG WINDS JUST OFF THE SURFACE AHEAD OF THE FRONT...WITH A THREAT OF LOW LEVEL WIND SHEAR UNTIL FRONTAL PASSAGE. THERE WILL ALSO BE A PERIOD OF RAIN WITH A LIKELIHOOD OF MVFR CONDITIONS ALONG AND BEHIND THE FRONT. ABOVE 2500 FEET NEAR THE VIRGINIA BORDER THE RAIN MAY MIX WITH OR CHANGE TO SNOW BEFORE ENDING EARLY THIS AFTERNOON. CONDITIONS SHOULD IMPROVE TO VFR AGAIN DURING THE LATE MORNING AND AFTERNOON...WITH THE IMPROVEMENT OCCURRING FIRST IN THE NORTHWEST PART OF THE FORECAST AREA AROUND 15Z AND REACHING THE VIRGINIA BORDER AREAS AROUND 21Z. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...WJM LONG TERM...ABE AVIATION...HAL ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 1204 PM CST THU DEC 4 2008 .AVIATION... CLOUD COVER CONTINUES TO HOLD FIRM OVER AREA AIRPORTS THIS MORNING BUT IS BEGINNING TO ERODE ACROSS CENTRAL LOUISIANA AS DRIER AIR FILTERS IN FROM THE NORTH. GUIDANCE INDICATES IFR/MVFR CEILINGS WILL CONTINUE THROUGH THE AFTERNOON AT KBPT/KLCH/KLFT/KARA BUT SLOWLY RISE BEFORE RAPIDLY DISSIPATING TO SKC. KAEX WILL SEE MORE RAPID DISSIPATION OF OVC WITH SKC POSSIBLE MUCH SOONER THAN CURRENTLY FORECAST. COULD ALSO SEE SOME VERY LIGHT DRIZZLE AT KLCH/KLFT/KARA THIS AFTERNOON BUT WILL NOT MENTION IN TAFS. WINDS WILL REMAIN NNE 10-15 KNOTS THROUGH THE AFTERNOON WITH A SLIGHT DECREASE OVERNIGHT. SHAMBURGER && .PREV DISCUSSION... /ISSUED 1025 AM CST THU DEC 4 2008/ DISCUSSION...SFC ANALYSIS INDICATES THE COLD FRONT WHICH PASSED OVERNIGHT IS NOW LOCATED OVER SERN MS/SERN LA. REGIONAL 88DS SHOW ALL BUT A FEW VERY LIGHT SHOWERS HAVE ALSO MOVED EAST OF THE AREA...THE FEW LIGHT SHOWERS ARE LOCATED OFF ATCHAFALAYA BAY. THEREFORE HAVE DROPPED POPS FROM THE GRIDS/ZONES FOR THE REST OF THE DAY. MAIN HEADACHE FOR THE REST OF THE DAY WILL BE THE LINGERING CLOUD COVER AND ITS EFFECTS ON AFTERNOON TEMPS. VIS IMAGERY INDICATES CLOUDS ARE BEGINNING TO BREAK UP OVER THE EXTREME NRN ZONES AND THIS TREND SHOULD CONTINUE THROUGH SUNSET OVER THE REMAINDER OF THE FORECAST AREA. TWEAKED TEMP GRIDS BASED ON LATEST TRENDS BUT WITH MINIMAL CHANGES...BIGGEST CHANGE WAS OVER THE SERN ZONES WHERE TEMPS WERE DROPPED A CAT OR TWO. UPDATE OUT SHORTLY. PREV DISCUSSION... /ISSUED 520 AM CST THU DEC 4 2008/ AVIATION... A COLD DOME OF HIGH PRESSURE ACROSS EASTERN MONTANA WILL TRAVEL SOUTHEAST INTO KANSAS THIS EVENING. INTRUDING DRY AIR...ASSOCIATED WITH THE MONTANA HIGH...WILL SLOWLY WEAR AWAY THE POST-FRONTAL STRATUS. SKIES WILL CLEAR OUT BY LATE MORNING ACROSS THE LAKES REGION OF SOUTHEAST TEXAS...AND ACROSS THE BEAUMONT-LAKE CHARLES-ALEXANDRIA AIRWAY BY MIDAFTERNOON. STRATUS WILL LINGER AROUND THE LAFAYETTE-MORGAN CITY AIRWAY UNTIL EARLY THIS EVENING. COLD-ADVECTIONAL NORTHERLY WINDS WILL BEGIN BLOWING OUT OF THE NORTHEAST BY THIS EVENING. TRARES PREV DISCUSSION... /ISSUED 448 AM CST THU DEC 4 2008/ SYNOPSIS...THE COLD FRONT IS MOVING QUICKLY THROUGH SOUTH CENTRAL LOUISIANA...SOUTHEAST AT 30 MPH. TEMPERATURES ARE NOT FAR FROM EXPECTED MAXIMUMS AND SHOULD FALL INTO THE 50S FOR MOST LOCATIONS DURING THE DAY. WINDS SHOULD REMAIN QUITE BREEZY IN THE WAKE OF THE FRONT WHILE SHOWERS SHOULD BE ENDING OVER ACADIANA DURING THE MORNING. THERES A CHANCE THAT TEMPERATURES AROUND THE LAKES AREA OF SOUTHEAST TEXAS COULD DIP INTO THE MID 20S SATURDAY MORNING AS THE COLD HIGH PRESSURE RIDGE MOVES OVER THAT AREA. ANOTHER LIGHT FREEZE FOR THE REMAINDER OF THE AREA NORTH OF I-10 AS WINDS FINALLY DECOUPLE. SUNDAY SHOULD SEE A RESURGENT POLAR HIGH NOSE INTO THE AREA FROM CANADA, REINFORCING OUR NORTHERLY WINDS AND COOL TEMPS. SHORT TERM...LIKE SHOOTING FISH IN A BARREL ON EXPECTED DAY TIME MAX TEMPS AS STRONG COLD AIR ADVECTION AND MOISTURE IN THE BOUNDARY LAYER ABOVE THE SHALLOW COLD AIRMASS CHILLS TEMPS INTO THE 50S DURING THE DAY. THAT SAME STRATCU DECK AND BRISK WINDS SHOULD HELP KEEP TEMPS FROM PLUNGING TOO LOW TNITE. CLEARING SKIES AND DIMINISHING WINDS SHOULD ALLOW TEMPS TO FALL FRIDAY NIGHT. NAM GUIDANCE LOOKS TO HAVE A GOOD HANDLE ON THIS. LONG TERM...GFS AND EURO HINTING AT A STORM SYSTEM OVER THE SOUTHERN PLAINS ON TUESDAY. THIS WILL BE OUR NEXT SHOT AT RAIN AND POSSIBLY STRONG TO SEVERE THUNDERSTORMS COURTESY OF A GOOD WARM SECTOR AND A STRONG SOUTHERN JET. MARINE...COULD NOT RULE OUT GUSTS ABOVE 20 KNOTS FOR THE NEAR SHORE WATERS WHEN TAKING THE STRONG COLD ADVECTION INTO CONSIDERATION ALONG WITH RUC/NAM/GFS 20 KNOTTERS SO HOISTED THE SCA FOR THAT AREA AND EXTENDED THE SCAS TIL MID-MORNING FRIDAY. && .PRELIMINARY POINT TEMPS/POPS... KLCH 57 39 50 34 58 / 10 0 0 10 10 KBPT 55 37 50 34 59 / 10 0 0 10 10 KAEX 53 33 47 29 53 / 10 0 0 10 10 KLFT 58 43 49 34 56 / 20 0 0 10 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 9 AM CST FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM CAMERON, LA TO HIGH ISLAND, TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON, LA OUT 20 NM...COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA OUT 20 NM... WATERS FROM CAMERON, LA TO HIGH ISLAND, TX EXTENDING FROM 20 NM TO 60 NM...WATERS FROM INTRACOASTAL CITY, LA TO CAMERON, LA EXTENDING FROM 20 NM TO 60 NM...WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA EXTENDING FROM 20 NM TO 60 NM. && $$ la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 1025 AM CST THU DEC 4 2008 .DISCUSSION...SFC ANALYSIS INDICATES THE COLD FRONT WHICH PASSED OVERNIGHT IS NOW LOCATED OVER SERN MS/SERN LA. REGIONAL 88DS SHOW ALL BUT A FEW VERY LIGHT SHOWERS HAVE ALSO MOVED EAST OF THE AREA...THE FEW LIGHT SHOWERS ARE LOCATED OFF ATCHAFALAYA BAY. THEREFORE HAVE DROPPED POPS FROM THE GRIDS/ZONES FOR THE REST OF THE DAY. MAIN HEADACHE FOR THE REST OF THE DAY WILL BE THE LINGERING CLOUD COVER AND ITS EFFECTS ON AFTERNOON TEMPS. VIS IMAGERY INDICATES CLOUDS ARE BEGINNING TO BREAK UP OVER THE EXTREME NRN ZONES AND THIS TREND SHOULD CONTINUE THROUGH SUNSET OVER THE REMAINDER OF THE FORECAST AREA. TWEAKED TEMP GRIDS BASED ON LATEST TRENDS BUT WITH MINIMAL CHANGES...BIGGEST CHANGE WAS OVER THE SERN ZONES WHERE TEMPS WERE DROPPED A CAT OR TWO. UPDATE OUT SHORTLY. && .PREV DISCUSSION... /ISSUED 520 AM CST THU DEC 4 2008/ AVIATION... A COLD DOME OF HIGH PRESSURE ACROSS EASTERN MONTANA WILL TRAVEL SOUTHEAST INTO KANSAS THIS EVENING. INTRUDING DRY AIR...ASSOCIATED WITH THE MONTANA HIGH...WILL SLOWLY WEAR AWAY THE POST-FRONTAL STRATUS. SKIES WILL CLEAR OUT BY LATE MORNING ACROSS THE LAKES REGION OF SOUTHEAST TEXAS...AND ACROSS THE BEAUMONT-LAKE CHARLES-ALEXANDRIA AIRWAY BY MIDAFTERNOON. STRATUS WILL LINGER AROUND THE LAFAYETTE-MORGAN CITY AIRWAY UNTIL EARLY THIS EVENING. COLD-ADVECTIONAL NORTHERLY WINDS WILL BEGIN BLOWING OUT OF THE NORTHEAST BY THIS EVENING. TRARES PREV DISCUSSION... /ISSUED 448 AM CST THU DEC 4 2008/ SYNOPSIS...THE COLD FRONT IS MOVING QUICKLY THROUGH SOUTH CENTRAL LOUISIANA...SOUTHEAST AT 30 MPH. TEMPERATURES ARE NOT FAR FROM EXPECTED MAXIMUMS AND SHOULD FALL INTO THE 50S FOR MOST LOCATIONS DURING THE DAY. WINDS SHOULD REMAIN QUITE BREEZY IN THE WAKE OF THE FRONT WHILE SHOWERS SHOULD BE ENDING OVER ACADIANA DURING THE MORNING. THERES A CHANCE THAT TEMPERATURES AROUND THE LAKES AREA OF SOUTHEAST TEXAS COULD DIP INTO THE MID 20S SATURDAY MORNING AS THE COLD HIGH PRESSURE RIDGE MOVES OVER THAT AREA. ANOTHER LIGHT FREEZE FOR THE REMAINDER OF THE AREA NORTH OF I-10 AS WINDS FINALLY DECOUPLE. SUNDAY SHOULD SEE A RESURGENT POLAR HIGH NOSE INTO THE AREA FROM CANADA, REINFORCING OUR NORTHERLY WINDS AND COOL TEMPS. SHORT TERM...LIKE SHOOTING FISH IN A BARREL ON EXPECTED DAY TIME MAX TEMPS AS STRONG COLD AIR ADVECTION AND MOISTURE IN THE BOUNDARY LAYER ABOVE THE SHALLOW COLD AIRMASS CHILLS TEMPS INTO THE 50S DURING THE DAY. THAT SAME STRATCU DECK AND BRISK WINDS SHOULD HELP KEEP TEMPS FROM PLUNGING TOO LOW TNITE. CLEARING SKIES AND DIMINISHING WINDS SHOULD ALLOW TEMPS TO FALL FRIDAY NIGHT. NAM GUIDANCE LOOKS TO HAVE A GOOD HANDLE ON THIS. LONG TERM...GFS AND EURO HINTING AT A STORM SYSTEM OVER THE SOUTHERN PLAINS ON TUESDAY. THIS WILL BE OUR NEXT SHOT AT RAIN AND POSSIBLY STRONG TO SEVERE THUNDERSTORMS COURTESY OF A GOOD WARM SECTOR AND A STRONG SOUTHERN JET. MARINE...COULD NOT RULE OUT GUSTS ABOVE 20 KNOTS FOR THE NEAR SHORE WATERS WHEN TAKING THE STRONG COLD ADVECTION INTO CONSIDERATION ALONG WITH RUC/NAM/GFS 20 KNOTTERS SO HOISTED THE SCA FOR THAT AREA AND EXTENDED THE SCAS TIL MID-MORNING FRIDAY. && .PRELIMINARY POINT TEMPS/POPS... KLCH 57 39 50 34 58 / 10 0 0 10 10 KBPT 55 37 50 34 59 / 10 0 0 10 10 KAEX 53 33 47 29 53 / 10 0 0 10 10 KLFT 58 43 49 34 56 / 20 0 0 10 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 9 AM CST FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM CAMERON, LA TO HIGH ISLAND, TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON, LA OUT 20 NM...COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA OUT 20 NM... WATERS FROM CAMERON, LA TO HIGH ISLAND, TX EXTENDING FROM 20 NM TO 60 NM...WATERS FROM INTRACOASTAL CITY, LA TO CAMERON, LA EXTENDING FROM 20 NM TO 60 NM...WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA EXTENDING FROM 20 NM TO 60 NM. && $$ 25 la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 520 AM CST THU DEC 4 2008 .AVIATION... A COLD DOME OF HIGH PRESSURE ACROSS EASTERN MONTANA WILL TRAVEL SOUTHEAST INTO KANSAS THIS EVENING. INTRUDING DRY AIR...ASSOCIATED WITH THE MONTANA HIGH...WILL SLOWLY WEAR AWAY THE POST-FRONTAL STRATUS. SKIES WILL CLEAR OUT BY LATE MORNING ACROSS THE LAKES REGION OF SOUTHEAST TEXAS...AND ACROSS THE BEAUMONT-LAKE CHARLES-ALEXANDRIA AIRWAY BY MIDAFTERNOON. STRATUS WILL LINGER AROUND THE LAFAYETTE-MORGAN CITY AIRWAY UNTIL EARLY THIS EVENING. COLD-ADVECTIONAL NORTHERLY WINDS WILL BEGIN BLOWING OUT OF THE NORTHEAST BY THIS EVENING. TRARES && .PREV DISCUSSION... /ISSUED 448 AM CST THU DEC 4 2008/ SYNOPSIS...THE COLD FRONT IS MOVING QUICKLY THROUGH SOUTH CENTRAL LOUISIANA...SOUTHEAST AT 30 MPH. TEMPERATURES ARE NOT FAR FROM EXPECTED MAXIMUMS AND SHOULD FALL INTO THE 50S FOR MOST LOCATIONS DURING THE DAY. WINDS SHOULD REMAIN QUITE BREEZY IN THE WAKE OF THE FRONT WHILE SHOWERS SHOULD BE ENDING OVER ACADIANA DURING THE MORNING. THERES A CHANCE THAT TEMPERATURES AROUND THE LAKES AREA OF SOUTHEAST TEXAS COULD DIP INTO THE MID 20S SATURDAY MORNING AS THE COLD HIGH PRESSURE RIDGE MOVES OVER THAT AREA. ANOTHER LIGHT FREEZE FOR THE REMAINDER OF THE AREA NORTH OF I-10 AS WINDS FINALLY DECOUPLE. SUNDAY SHOULD SEE A RESURGENT POLAR HIGH NOSE INTO THE AREA FROM CANADA, REINFORCING OUR NORTHERLY WINDS AND COOL TEMPS. SHORT TERM...LIKE SHOOTING FISH IN A BARREL ON EXPECTED DAY TIME MAX TEMPS AS STRONG COLD AIR ADVECTION AND MOISTURE IN THE BOUNDARY LAYER ABOVE THE SHALLOW COLD AIRMASS CHILLS TEMPS INTO THE 50S DURING THE DAY. THAT SAME STRATCU DECK AND BRISK WINDS SHOULD HELP KEEP TEMPS FROM PLUNGING TOO LOW TNITE. CLEARING SKIES AND DIMINISHING WINDS SHOULD ALLOW TEMPS TO FALL FRIDAY NIGHT. NAM GUIDANCE LOOKS TO HAVE A GOOD HANDLE ON THIS. LONG TERM...GFS AND EURO HINTING AT A STORM SYSTEM OVER THE SOUTHERN PLAINS ON TUESDAY. THIS WILL BE OUR NEXT SHOT AT RAIN AND POSSIBLY STRONG TO SEVERE THUNDERSTORMS COURTESY OF A GOOD WARM SECTOR AND A STRONG SOUTHERN JET. MARINE...COULD NOT RULE OUT GUSTS ABOVE 20 KNOTS FOR THE NEAR SHORE WATERS WHEN TAKING THE STRONG COLD ADVECTION INTO CONSIDERATION ALONG WITH RUC/NAM/GFS 20 KNOTTERS SO HOISTED THE SCA FOR THAT AREA AND EXTENDED THE SCAS TIL MID-MORNING FRIDAY. && .PRELIMINARY POINT TEMPS/POPS... KLCH 54 39 50 34 58 / 10 0 0 10 10 KBPT 52 37 50 34 59 / 10 0 0 10 10 KAEX 51 33 47 29 53 / 10 0 0 10 10 KLFT 64 43 49 34 56 / 20 0 0 10 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 9 AM CST FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM CAMERON, LA TO HIGH ISLAND, TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON, LA OUT 20 NM...COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA OUT 20 NM... WATERS FROM CAMERON, LA TO HIGH ISLAND, TX EXTENDING FROM 20 NM TO 60 NM...WATERS FROM INTRACOASTAL CITY, LA TO CAMERON, LA EXTENDING FROM 20 NM TO 60 NM...WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA EXTENDING FROM 20 NM TO 60 NM. && $$ la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 448 AM CST THU DEC 4 2008 .SYNOPSIS...THE COLD FRONT IS MOVING QUICKLY THROUGH SOUTH CENTRAL LOUISIANA...SOUTHEAST AT 30 MPH. TEMPERATURES ARE NOT FAR FROM EXPECTED MAXIMUMS AND SHOULD FALL INTO THE 50S FOR MOST LOCATIONS DURING THE DAY. WINDS SHOULD REMAIN QUITE BREEZY IN THE WAKE OF THE FRONT WHILE SHOWERS SHOULD BE ENDING OVER ACADIANA DURING THE MORNING. THERES A CHANCE THAT TEMPERATURES AROUND THE LAKES AREA OF SOUTHEAST TEXAS COULD DIP INTO THE MID 20S SATURDAY MORNING AS THE COLD HIGH PRESSURE RIDGE MOVES OVER THAT AREA. ANOTHER LIGHT FREEZE FOR THE REMAINDER OF THE AREA NORTH OF I-10 AS WINDS FINALLY DECOUPLE. SUNDAY SHOULD SEE A RESURGENT POLAR HIGH NOSE INTO THE AREA FROM CANADA, REINFORCING OUR NORTHERLY WINDS AND COOL TEMPS. && .SHORT TERM...LIKE SHOOTING FISH IN A BARREL ON EXPECTED DAY TIME MAX TEMPS AS STRONG COLD AIR ADVECTION AND MOISTURE IN THE BOUNDARY LAYER ABOVE THE SHALLOW COLD AIRMASS CHILLS TEMPS INTO THE 50S DURING THE DAY. THAT SAME STRATCU DECK AND BRISK WINDS SHOULD HELP KEEP TEMPS FROM PLUNGING TOO LOW TNITE. CLEARING SKIES AND DIMINISHING WINDS SHOULD ALLOW TEMPS TO FALL FRIDAY NIGHT. NAM GUIDANCE LOOKS TO HAVE A GOOD HANDLE ON THIS. && .LONG TERM...GFS AND EURO HINTING AT A STORM SYSTEM OVER THE SOUTHERN PLAINS ON TUESDAY. THIS WILL BE OUR NEXT SHOT AT RAIN AND POSSIBLY STRONG TO SEVERE THUNDERSTORMS COURTESY OF A GOOD WARM SECTOR AND A STRONG SOUTHERN JET. && .MARINE...COULD NOT RULE OUT GUSTS ABOVE 20 KNOTS FOR THE NEAR SHORE WATERS WHEN TAKING THE STRONG COLD ADVECTION INTO CONSIDERATION ALONG WITH RUC/NAM/GFS 20 KNOTTERS SO HOISTED THE SCA FOR THAT AREA AND EXTENDED THE SCAS TIL MID-MORNING FRIDAY. && .PRELIMINARY POINT TEMPS/POPS... KLCH 54 39 50 34 58 / 10 0 0 10 5 KBPT 52 37 50 34 59 / 10 0 0 10 5 KAEX 51 33 47 29 53 / 10 0 0 10 5 KLFT 64 43 49 34 56 / 20 0 0 10 5 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 9 AM CST FRIDAY FOR THE FOLLOWING ZONES: WATERS FROM CAMERON, LA TO HIGH ISLAND, TX EXTENDING FROM 20 NM TO 60 NM...WATERS FROM INTRACOASTAL CITY, LA TO CAMERON, LA EXTENDING FROM 20 NM TO 60 NM...WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA EXTENDING FROM 20 NM TO 60 NM. SMALL CRAFT ADVISORY UNTIL 9 AM CST FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM CAMERON, LA TO HIGH ISLAND, TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON, LA OUT 20 NM...COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA OUT 20 NM. && $$ SWEENEY la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 535 AM EST FRI DEC 5 2008 .SYNOPSIS... HIGH PRESSURE WILL BUILD IN FROM THE WEST THIS AFTERNOON AND CREST OVER THE AREA TONIGHT. A TROUGH OF LOW PRESSURE WILL APPROACH FROM THE WEST SATURDAY INTO SATURDAY NIGHT. THE TROUGH WILL DEVELOP ONE LOW CENTER NEAR THE GULF OF MAINE AND ANOTHER OVER EASTERN NOVA SCOTIA ON SUNDAY. THE TWO LOWS WILL CONSOLIDATE OVER THE MARITIMES SUNDAY NIGHT AND LIFT NORTH ACROSS LABRADOR ON MONDAY. && .NEAR TERM /THROUGH TONIGHT/... MAIN CONCERNS WILL BE CLOUDS AND THE SCA FOR THE MARINE SECTION. A QUICK UPDATE TO ADD SOME ACCUMULATION ACROSS THE FAR N (MEZ002,005-006) DUE TO A BAND OF SNOW IN ASSOCN W/SOME PVA FROM THAT UPPER LEVEL FEATURE MOVING IN FROM QUEBEC. LESS THAN AN INCH OF SNOW IS EXPECTED. SNOW RATIO AROUND 20:1. BOOSTED POPS A BIT TO ACCOUNT FOR WHAT THE LATEST RADAR WAS SHOWING. SOME TWEAKS WERE MADE TO THE TEMPS. THE CARWRF AND RUC CONTINUE TO HANDLE THE LATEST CONDITIONS QUITE WELL AND THEREFORE FOLLOWED THIS BLEND THROUGH TODAY. KEPT MORE CLOUDS ACROSS THE NORTHERN 1/2 OF THE CWA TODAY. MDL SOUNDINGS SHOW DEEP MOISTURE FROM 925-850MBS IN THE AFOREMENTIONED REGION. DECIDED ON GOINGS CLOUDY ACROSS THE NORTH AND WEST AND PARTLY CLOUDY CONDITIONS FOR THE INTERIOR DOWNEAST AND COASTAL REGIONS. A VORT MAX MOVING ACROSS SOUTHERN QUEBEC THIS MORNING IS FCST TO MOVE ACROSS THE NORTHERN PORTION OF THE CWA TODAY AIDING IN SOME FLURRY OR SNOW SHOWER ACTIVITY. KEPT 20-30% POPS ACROSS THE NORTH AND WEST THROUGH THE AFTERNOON. MADE ADJUSTMENTS TO THE HRLY TEMPS/DWPTS USING THE RTMA AND GMOS BC. GMOS AND NAM12 TEMPS NOT CATCHING TO COOLER TEMPS ACROSS THE NORTH AND WEST. TWEAKED MAX TEMPS TODAY AS WELL KNOCKING THEM DOWN BY 3 DEGS WHICH PUTS LOW TO MID 20S ACROSS THE NORTH AND WEST. MID/UPPER 30S EXPECTED FOR THE DOWNEAST AND COAST. CLOUDS ARE EXPECTED TO DISSIPATE TONIGHT AS THE MDL SOUNDINGS DRYING THROUGH 850 MBS WHICH SHOULD LEAD TO SOME CLEARING. THE EXCEPTION TO THIS WILL BE THE WESTERN AREAS AS UPSLOPE EFFECTS COULD KEEP MORE CLOUDS AROUND LONGER. TIRED TO ACCOUNT FOR THIS IN THE GRIDS USING THE BTV_SKY TOOL WHICH GAVE PARTLY SKIES. TEMPERATURES WILL BE SOME 5 TO 10 DEGS COLDER THAN THEY WERE SOME 24 HRS AGO AT THIS TIME SATURDAY MORNING. OVERNIGHT MINS ARE EXPECTED TO DROP BACK INTO THE MID TEENS ACROSS THE NORTH AND UPPER TEENS AND LOWER 20S FOR THE DOWNEAST AND THE COAST. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... A LARGE TROUGH WILL BE DIGGING INTO THE MIDWEST ON SATURDAY. ONE BUNDLE OF ENERGY WILL BE ROUNDING THE BOTTOM OF THE TROUGH THROUGH THE SOUTHERN BRANCH AND OFF THE SOUTHEAST COAST LATE SATURDAY AS ANOTHER BUNDLE OF ENERGY ACROSS THE NORTHERN BRANCH WILL BE DIGGING INTO THE GREAT LAKES. THE SOUTHERN BRANCH ENERGY WILL BE FORMING A LOW SOUTH OF NOVA SCOTIA LATER SUNDAY NIGHT INTO MONDAY WHILE THE NORTHERN BRANCH FORMS A LOW IN THE GULF OF MAINE. THIS BRINGS A CHALLENGING FORECAST. THE INTERIOR LOW CARRIES LOTS OF UPPER LEVEL ENERGY BUT MOISTURE MAY BE LIMITED IF THE OUTER LOW WELL TO THE EAST OBSTRUCTS SIGNIFICANT INFLOW OF ATLANTIC MOISTURE. THIS WOULD BRING A LIGHT SNOWFALL OF 2 TO 3 INCHES ACROSS THE AREA. HOWEVER...THE CANADIAN...ECMWF AND SREF CONSOLIDATE THE TWO LOWS INTO ONE OVER THE MARITIMES MORE RAPIDLY THAN EITHER THE NAM OR THE GFS. A QUICKER CONSOLIDATION WOULD ALLOW A MORE ORGANIZED AREA OF SNOW TO BACK IN FROM THE EAST BRINGING HEAVIER SNOW TO THE REGION...ESPECIALLY OVER THE EAST. FOR NOW VERY CONFIDENT WE`LL SEE SNOW SO WILL GO CAT POPS SUNDAY AFTERNOON...WITH AMOUNTS STILL HAVING TO BE RESOLVED. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... SNOW ACROSS THE AREA WILL LIFT OUT TO THE NORTHEAST SUNDAY NIGHT AS THE LOW LIFTS AWAY INTO EASTERN CANADA. THE LOW WILL LIKELY INTENSIFY AS IT CONSOLIDATES TO OUR NORTHEAST. NORTHWEST WINDS BEHIND THE LOW WILL LIKELY RESULT IN BLOWING AND DRIFTING. HIGH PRESSURE WILL BUILD IN ON MONDAY AND CREST OVER THE AREA MONDAY NIGHT. A MOIST BUT SOMEWHAT DISORGANIZED SYSTEM WILL APPROACH TUESDAY BRINGING A CHANCE FOR SNOW NORTH AND SNOW OR RAIN CENTRAL AND DOWNEAST TUESDAY INTO TUESDAY NIGHT. SOME COLD ARCTIC AIR MAY THEN APPROACH FOR MID WEEK. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... NEAR TERM: MVFR CIGS ACROSS THE NORTHERN TAF SITES INTO EARLY AFTERNOON AND THEN CONDITIONS LOOK TO IMPROVE TO VFR THROUGH TONIGHT. KBGR AND KBHB WILL STAY VFR. SHORT TERM: VFR TO MVFR CONDITIONS SATURDAY WILL LOWER TO IFR SATURDAY NIGHT INTO SUNDAY EVENING AS SNOW MOVES ACROSS THE AREA. CONDITIONS WILL IMPROVE TO VFR DOWNEAST EARLY MONDAY MORNING AND ACROSS THE NORTH LATER MONDAY. VFR CONDITIONS ARE THEN EXPECTED INTO MONDAY NIGHT BEFORE LOWERING TO IFR IN LOW CLOUDS AND PRECIPITATION ON TUESDAY. && .MARINE... NEAR TERM: THE SCA WAS EXTENDED THROUGH LATE MORNING AS WINDS/SEAS STILL W/IN SCA RANGE ESP THE SEAS. USED A BLEND OF THE NAM12/GFS FOR THE WINDS WHICH GIVES 15-20 KT INTO THE AFTERNOON. GUSTS UP TO 25 KT WERE ADDED. THE SWANNAM WAVE HEIGHTS MATCHING VERY WELL THIS MORNING AND DECIDED TO USE IT TO INITIALIZE THE GRIDS AND THEN BLENDED THE WNAWAVE4 FOR THIS AFTERNOON INTO TONIGHT. THIS SHOWS CONDITIONS GOING BELOW SCA AFT 18Z OR SO. SHORT TERM: WINDS WILL BE LIGHT AS THE LOW APPROACHES THROUGH SUNDAY. STRONG WINDS POSSIBLY REQUIRING A GALE ARE THEN LIKELY BEHIND THE LOW SUNDAY EVENING INTO MONDAY AS THE LOW INTENSIFIES TO OUR NORTHEAST. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR ANZ050>052. && $$ NEAR TERM...HEWITT SHORT TERM...BLOOMER LONG TERM...BLOOMER AVIATION...HEWITT MARINE...HEWITT/BLOOMER me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 315 AM EST THU DEC 4 2008 .SYNOPSIS... A STRONG COLD FRONT WILL APPROACH FROM THE WEST TODAY AND THEN MOVE ACROSS THE REGION LATE THIS AFTERNOON INTO THIS EVENING. MUCH COLDER AIR WILL POUR INTO THE AREA TONIGHT BEHIND THE COLD FRONT. AN UPPER LEVEL DISTURBANCE IS EXPECTED TO CROSS THE REGION FRIDAY REINFORCING THE COLD AIR ACROSS THE AREA. HIGH PRESSURE WILL THEN REMAIN ACROSS THE REGION THROUGH SATURDAY. LOW PRESSURE MAY BRING SOME SNOW TO THE AREA LATER SUNDAY AND SUNDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... MAIN CHALLENGE WILL BE THE TIMING OF THE COLD FRONT AND QPF AMOUNTS. DECIDED ON USING THE CARWRF INTO THIS AFTERNOON W/THE RUC13 TO START OUT THIS MORNING. THE SREF AND GFS40 WERE USED FOR THE GRIDS TONIGHT. LAST SATL IMAGERY SHOWED BATCH OF MID-LVL CLOUDS MOVING NE ACROSS ACROSS THE NORTHERN AND EASTERN PORTION OF THE CWA. LARGE AREA OF CLEARING MOVING IN BEHIND THESE CLOUDS. LARGE BATCH OF SCU AND AC MOVING ACROSS ONTARIO AND QUEBEC IN ASSOCN W/THE COLD FRONT. CARWRF SHOWED THIS NICELY AND DECIDED TO BRING CLOUDS THICKENING BY LATE MORNING AND OVERSPREADING THE CWA BY THE AFTERNOON. TEMPS ARE EXPECTED TO WARM AHEAD THE FRONT INTO THE AFTERNOON. 00Z UA ANAL SHOWED THIS WARMING MOVING INTO NYS AND SOUTHERN NEW ENG. WE ARE LOOKING FOR TEMPS TO SHOOT INTO THE UPPER 30S ACROSS THE NORTH AND LOWER 40S FOR THE CENTRAL HIGHLANDS AND DOWNEAST THIS AFTERNOON. PRECIP SHIELD WILL MOVE IN LATER THIS MORNING AND THEN MIGRATE E ACROSS THE CWA THIS AFTERNOON. USING THE TEMPERATURE PROFILES IN THE GRIDS...IT LOOKS LIKE PRECIP WILL BE IN THE FORM OF RAIN SHOWERS TO START ACROSS THE NORTH AND WEST W/SOME SNOW MIXED IN TO START AND THEN THINGS GRADUALLY GO TO SNOW SHOWERS THIS AFTERNOON AS COLDER AIR FILTERS DOWN THROUGH THE COLUMN. DECIDED TO BACK DOWN ON COOLING THINGS OFF TOO QUICK AS INDICATED BY THE CARWRF TEMPS. RAIN SHOWERS FOR THE CENTRAL HIGHLANDS AND DOWNEAST. SOME DECENT FRONTOGENETICAL FORCING IS THERE FROM 850-700 MBS SUPPORTED BY THE CARWRF AND THE GFS. A NARROW BAND OF PRECIP EXPECTED W/THIS SETUP. THEREFORE...CARRIED CATEGORICAL POPS FOR A WHILE THIS AFTERNOON ACROSS THE NORTH AND WEST AS THE FRONT SLIDES THROUGH. CHC POPS FOR THE DOWNEAST AREAS W/LESS FORCING. MDL SOUNDINGS AND BUFKIT PROFILES INDICATE SOME SLEET THIS AFTERNOON AS THE FRONT ARRIVES W/THAT COLDER DESCENDING DOWN THROUGH THE COLUMN. ATTM...JUST HAVE SNOW SHOWERS. COULD BE MORE OF A GRAUPEL PRECIP. QPF AMOUNTS ON THE AVERAGE OF .05-.10" AND THIS MAINLY FOR THE NORTHERN 1/2 OF THE CWA. FAR NORTHERN AREAS AND HIGHER ELEVATIONS COULD GET CLOSE TO AN INCH OF SNOW BY THE EVENING. SNOW GRIDS ARE A REFLECTION OF THE CARWRF AND GFS MDL. THE FRONT IS EXPECTED TO BE AT THE COAST BY THE EVENING. MUCH COLDER AIR SEEPING IN AS 850MB FRONT MOVES ACROSS THE REGION. KEPT CHC POPS IN ACROSS THE NORTH AND WEST THIS EVENING TO ACCOUNT FOR THIS FEATURE. CLOUDS WILL BEGIN TO BREAK UP BY DAYBREAK FRIDAY AS DRIER AIR WORKS IN. GMOS TEMPS FOR TONIGHT LOOKED DECENT AND WERE ACCEPTED. SOME ADJUSTMENTS WERE MADE DOWNWARD FOR THE LOW LYING AREAS. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... FRI AND SAT APPEAR TO BE MSLY DRY AND SEASONABLY COLD WITH TYPICAL SC CLD CVR AND FLURRIES MSLY FOR NRN/WRN PTNS OF THE FA. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AFTWRDS...MODELS CONT TO INDICATE A STRONG DIGGING S/WV COMPLEX ADVANCING SE FROM CNTRL CAN INTO THE LOWER GREAT LKS AND OH VLY. THE 00Z ECMWF CONTS TO BE THE MOST AGRESSIVE WITH THIS SYSTEM...FORMING A SECONDARY SFC LOW SOMEWHERE OFF THE MID ATLC COAST SAT NGT AND TRACKING IT NE TOWARD WRN NOVA SCOTIA ON SUN AND INTO THE GULF OF SAINT LAWRENCE SUN NGT. THIS SCENARIO WOULD RESULT CLDS TO INCREASE OVR THE FA SAT NGT AND ALLOW THIS SYSTEM TO FORM AN ORGANIZE PRECIP SHIELD TO RESULT IN POTENTIALLY SIGNIFICANT AMOUNTS OF SNFL DUE TO ATLC MOISTURE INFLOW...ESPECIALLY INLAND FROM THE IMMEDIATE COAST OVR ERN PTNS OF THE FA. COASTAL AREAS MAY EXPERIENCE ENOUGH LLVL WARMING FROM THE ATLC FOR SN TO MIX OR EVEN CHG OVR TO RN SUN AFT/ERLY EVE. IN ANY EVENT...THE TREND ADVERTISED BY THE ECMW IS BACKED UP ENOUGH BY THE 00Z GFS AND GFS ENS MEMBERS TO INCREASE POPS TO THE LIKELY CATEGORY SUN INTO SUN EVE FOR THE FA. SN SHOULD TAPER TO SN SHWRS ACROSS THE FA BY MON MORN...CONTG THRU THE AFT BEFORE ENDING MON NGT AS A NARROW RIDGE OF HI PRES APCHS AND CROSSES THE FA. BOTH THE GFS AND ECMWF INCREASE CLDS QUICKLY OVR THE FA ON TUE AS MID/UPPER WARM ADVCN BEGINS IN EARNEST. SNFL SHOULD AGAIN OVERSPREAD THE AF BY TUE AFT AND CONT TUE NGT. THE 00Z GFS OPNL MODEL RUN INDICATES THAT ENOUGH MID/LLVL WARM AIR SHOULD ARRIVE TO TRANSITION SNFL TO RN OR MIXED RN/SN OVR SPCLY ERN PTNS OF THE FA LATE TUE NGT INTO WED BEFORE COLDER AIR MOVES BACK INTO THE FA BEHIND A FIRST WV OF LOW PRES PROGGED TO DEPART THE FA BY WED NGT. THERE THE MODELS DVRG...WITH OPNL RUNS AND SOME OF THE GFS ENS MEMBERS INDICATING A POTENTIALLY STRONGER SECONDARY TO IMPACT THE FA ON THU. FOR NOW GVN MODEL LOW PRES TEMPORAL/SPATIAL UNCERTAINTIES WITH THIS SYSTEM...WE HAVE OPTED TO KEEP POPS IN THE CHC CATEGORY FOR NOW WITH THIS EVENT. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... NEAR TERM: VFR THIS MORNING DROPPING BACK TO MVFR THIS AFTERNOON INTO THE EVENING FOR THE NORTHERN TAF SITES. KBGR AND KBHB SHOULD SEE VFR THROUGH TONIGHT. SHORT TERM: HI MVFR CLGS TO VFR CONDITIONS WILL PREVAIL ACROSS THE FA FRI INTO SAT NGT...WITH THE BEST CHC OF MVFR CLGS ACROSS NRN TAF SITES. ALL SITES WILL LOWER TO MVFR/IFR IN CLGS AND SNFL SUN INTO SUN NGT. DOWNEAST SITES SHOULD RECOVER TO VFR ON MON WHILE NRN TAF SITES REMAIN MVFR IN OCNL SN SHWRS. && .MARINE... NEAR TERM: EXTENDED THE SCA INTO EARLY FRIDAY MORNING. WINDS/SEAS ON THE RISE ATTM. EXPECTING SCA CONDITIONS BY LATE MORNING THESE CONDITIONS ARE EXPECTED INTO TONIGHT. PREV WIND AND WAVE HEIGHT GRIDS IN GREAT SHAPE PER LATEST OBS. ONLY SLIGHT ADJUSTMENTS NEEDED AND THIS WAS FOR THE GUSTS INTO THE EVENING. SHORT TERM: STRONG SCA TO POSSIBLY GALES CAN BE XPCTD ON THE BACK SIDE OF THE DEPARTING LATE WEEKEND LOW INTO MON ACROSS OUR WATERS. WE USED THE WNA WW3 DATA FO WV HTS AND A BLEND OF GFS...NAM AND GFS MOS FOR WINDS. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST FRIDAY FOR ANZ050>052. && $$ NEAR TERM...HEWITT SHORT TERM...VJN LONG TERM...VJN AVIATION...HEWITT MARINE...HEWITT/VJN me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 357 AM EST THU DEC 4 2008 .SYNOPSIS... A COLD FRONT WILL MOVE ACROSS THE MID ATLANTIC LATER TODAY AND TONIGHT. CANADIAN HIGH PRESSURE BEHIND THE FRONT WILL BRING COLDER CONDITIONS FRIDAY AND SATURDAY. A DISTURBANCE WILL MOVE THROUGH SATURDAY NIGHT INTO EARLY SUNDAY WITH A CHANCE OF SNOW SHOWERS. HIGH PRESSURE RETURNS MONDAY BEFORE A STORM SYSTEM APPROACHES ON TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... RAIN SHOWERS ALREADY BREAKING UP EARLY THIS MORNING ACROSS THE NRN SHEN VALLEY AND NCNTRL MD. THESE SEEM TO BE ASSOCIATED WITH WEAK WARM ADVECTION AND SOME ELEVATED INSTABILITY AS NOTED ON RUC40 FCST SOUNDINGS. THESE WILL LIKELY DISSIPATE AROUND MID MORNING AS LOW-LVL JET WEAKENS. ANOTHER AREA OF RAIN/SHOWERS WEST OF THE APPALACHIANS WILL WORK GRADUALLY EAST THROUGH THE DAY AHEAD OF A COLD FRONT. ALTHOUGH UPPER LEVEL SUPPORT IS FCST TO WEAKEN BELIEVE THERE WILL BE ENOUGH CVRG TO JUSTIFY LIKELY POPS BUT AMTS WILL BE RATHER LIGHT IN THE ORDER OF A FEW HUNDREDTHS. PRECIP WILL TURN TO SNOW OVER THE HIGHER ELEVS OF THE WEST BUT ONLY LOOKING FOR MINUSCULE AMTS. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... PRECIP WILL SHIFT SOUTHEAST OF THE AREA BY 03-04Z BEFORE THE DEEP COLD AIR ARRIVES. SO ALL LIQUID. /LFR CANADIAN HIGH PRESSURE BUILDS INTO THE MID ATLANTIC FRIDAY AND FRIDAY NIGHT. HIGH PRESSURE WILL INFUSE A COLDER AIR MASS ACROSS THE AREA. SAVE FOR A FEW UPSLOPE SNOW SHOWERS ACROSS THE HIGHLANDS FRIDAY MORNING...DRIER AIR WILL MEAN A PRECIPITATION FREE FORECAST THROUGH FRIDAY NIGHT. HOWEVER...A REINFORCING SHORTWAVE /VORT MAX/ IS PROGGED BY THE MODELS TO SHEAR ACROSS THE AREA LATER FRIDAY INTO FRIDAY NIGHT SO SOME CLOUD COVER WILL REMAIN. GRIDS REFLECT 40-60 PCT SKY COVER. MAX T FRIDAY AND MIN T FRIDAY NIGHT WILL BE BELOW NORMAL BY SEVERAL DEGREES. UNDERCUT GFS MOS ESPECIALLY FRIDAY NIGHT WITH HIGH PRESSURE OVERHEAD PROMOTING OPTIMAL RADIATIONAL COOLING CONDITIONS. /PELOQUIN && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... HIGH PRESSURE SCOOTS OFF THE EASTERN SEABOARD ON SATURDAY...ALLOWING A RETURN FLOW TO SET UP DURING THE AFTERNOON. WARM ADVECTION WILL DEVELOP AHEAD OF A SHORTWAVE OVER THE GREAT LAKES/UPPER MID WEST BY AFTERNOON. GFS INDICATES LIFT ON ISENTROPIC SURFACES MOST PRONOUNCED ACROSS THE WESTERN CWA DURING THE AFTERNOON...AND THIS IS WHERE LOW POPS WILL RESIDE. EAST OF THE MTNS SHOULD REMAIN DRY DURING THE DAYLIGHT HOURS SATURDAY...BUT WARM ADVECTION WILL DENOTE AN INCREASE AND THICKENING OF CLOUDS DURING THE AFTERNOON. SHORTWAVE MOVES ACROSS THE MID ATLANTIC SATURDAY NIGHT INTO EARLY SUNDAY. LIFT SPREADS FURTHER EAST ACROSS THE CWA. MOISTURE IS NOT ABUNDANT BUT IS SUFFICIENT FOR AT LEAST SCATTERED PRECIPITATION SATURDAY NIGHT. HAVE THE HIGHEST POPS /LIKELY/ ACROSS THE HIGHLANDS WHERE AN UPSLOPE COMPONENT WILL ENHANCE PRECIPITATION. WE MAY NEED TO CONSIDER INCREASING POPS TO LIKELY FURTHER EAST IF THE MODELS CONTINUE TO INDICATE A STRONGER SHORTWAVE. TEMPERATURE PROFILES SUGGEST THAT PRECIPITATION WILL FALL IN THE FORM OF SNOW...EXCEPT PERHAPS RAIN INITIALLY ACROSS LOWER SOUTHERN MARYLAND. BEST CHANCE OF ACCUMULATIONS WILL BE ACROSS THE HIGHLANDS...WHERE WINTER WEATHER ADVISORY CRITERIA MAY BE ACHIEVED. HOWEVER...THERE IS A CHANCE FOR LIGHT ACCUMULATIONS OF SNOW TO EXTEND FURTHER EAST ACROSS THE REST OF THE CWA ALL THE WAY TO THE CHESAPEAKE BAY. PRECIPITATION EXITS EARLY SUNDAY AS THE SHORTWAVE AXIS MOVES EAST...EXCEPT FOR SNOW SHOWERS IN FAVORED UPSLOPE PARTS OF THE HIGHLANDS. CYCLONIC FLOW WILL KEEP PLENTY OF CLOUDS AROUND SUNDAY...THEN HIGH PRESSURE BUILDS IN SUNDAY NIGHT INTO MONDAY. THIS WILL MEAN AN END TO UPSLOPE SNOW SHOWERS AND LESS CLOUDS FOR MONDAY. TUESDAY INTO WEDNESDAY...OPERATIONAL MODELS AND MEDIUM RANGE ENSEMBLES CONTINUE TO INDICATE A STORM SYSTEM AFFECTING THE CWA. HOWEVER...THERE REMAINS DISAGREEMENT AS TO DETAILS /LIKE TIMING AND STRENGTH/ OF THE STORM SYSTEM. ONE THING WHICH HAS BEEN RELATIVELY CONSISTENT IS THAT THIS APPEARS TO BE PRIMARILY A RAIN EVENT. HOWEVER...IF PRECIPITATION MOVES IN EARLY ENOUGH /TUESDAY MORNING/...THEN SOME WINTRY PRECIPITATION IS POSSIBLE AT THE ONSET. SPECIFICS WILL BECOME MORE CLEAR AND WE MOVE CLOSER IN TIME TO NEXT WEEK. && .AVIATION /09Z THURSDAY THROUGH MONDAY/... VFR CONDITIONS EXPECTED THRU THURSDAY MORNING. MIDLEVEL CLOUDS WILL MOVE INTO THE TERMINALS AROUND DAYBREAK AS A CDFNT APPROACHES. CIGS WILL LOWER DURING THE DAY BEHIND THE FRONT AND DROP TO MVFR LEVELS AT TIMES THURSDAY AFTERNOON/EVENING ESPECIALLY DURING HEAVIER RAIN SHOWERS...EXCEPT AT FAR S TERMINALS WHERE LIMITED LOW LVL MOISTURE SHOULD ALLOW CIGS TO STAY AT VFR LVLS. S FLOW OVERNIGHT WILL VEER THROUGHOUT THE DAY...BECOMING NW LATE THURSDAY AS THE CDFNT PUSHES E OF THE REGION. CLRING CONDITIONS ARE EXPECTED THURSDAY NIGHT. /JRK HIGH PRESSURE BUILDS IN FRIDAY AND FRIDAY NIGHT AND THEN MOVES OFF THE COAST ON SATURDAY. A SHORTWAVE WILL MOVE THROUGH SATURDAY NIGHT INTO EARLY SUNDAY WITH A CHANCE OF SNOW SHOWERS. ANOTHER GUSTY NORTHWEST WIND IS EXPECTED ON SUNDAY. HIGH PRESSURE RETURNS MONDAY. /PELOQUIN && .MARINE... SCA CONDITIONS EXPECTED TODAY AND TONIGHT WITH GUSTS UP TO 20 KT. /LFR A SHORTWAVE MOVING THROUGH SATURDAY NIGHT WILL BRING SMALL CRAFT ADVISORY WINDS IN ITS WAKE SUNDAY AND SUNDAY NIGHT. HIGH PRESSURE BUILDS IN MONDAY...BUT A STORM SYSTEM MAY IMPACT THE WATERS TUESDAY INTO WEDNESDAY WITH AT LEAST SMALL CRAFT ADVISORY CONDITIONS. /PELOQUIN && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST FRIDAY FOR ANZ530>537. && $$ SYNOPSIS...PELOQUIN NEAR TERM...LFR SHORT TERM...LFR/PELOQUIN LONG TERM...PELOQUIN AVIATION...JRK/PELOQUIN MARINE...LFR/PELOQUIN md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1247 PM EST FRI DEC 5 2008 LATEST UPDATE...AVIATION... .SYNOPSIS...(459 AM EST FRI DEC 5 2008) LAKE EFFECT SNOW SHOWERS WILL GRADUALLY DIMINISH ACROSS THE AREA DURING THE DAY TODAY AS A PORTION OF A RIDGE OF HIGH PRESSURE MOVES ACROSS THE AREA TODAY. SNOW IS EXPECTED TO INTENSIFY ACROSS THE AREA THEN OVERNIGHT TONIGHT AS AN AREA OF LOW PRESSURE OVER ALBERTA THIS MORNING APPROACHES THE AREA. MOST AREAS WILL SEE AT LEAST A COUPLE OF INCHES OF SNOW FROM TONIGHT THROUGH SATURDAY NIGHT. HEAVIER AMOUNTS OF SNOW ARE LIKELY NORTHWEST OF A LINE FROM HOLLAND TO BALDWIN AS SOUTHWEST WINDS WILL ALLOW LAKE MICHIGAN TO ENHANCE SNOWFALL. && .SHORT TERM...(1015 AM EST FRI DEC 5 2008) (REST OF TODAY THROUGH SUNDAY) I HAVE UPGRADED THE LAKE EFFECT SNOW ADVISORY TO A LAKE EFFECT SNOW WARNING SINCE WE HAVE HAD SEVERAL REPORTS OF BETWEEN 8 TO 10 INCHES IN EXTREME SOUTHWESTERN KENT...EASTERN OTTAWA AND NORTHEAST ALLEGAN COUNTIES IN THE PAST THREE HOURS. ALSO...SINCE THE LATEST RUC SHOWS THE LOW LEVEL WIND CONVERGENCE CONTINUES THROUGH MID AFTERNOON AND SHIFTS NORTH ONLY SLIGHTLY... I EXPECTED THE TIME OF THE HEADLINES UNTIL 5 PM FOR BOTH THE WARNING AND ADVISORY COUNTIES. OUR 88D RADAR CONTINUES TO SHOW ECHO INTENSITIES OVER 30 DBZ CONTINUING TO DEVELOP OVER THE LAKE SHORE AREAS OF OTTAWA AND ALLEGAN COUNTIES THAT THEN MOVE INLAND. GIVEN THE RUC KEEPS THE LIFT AND CONVERGENCE GOING INTO MID AFTERNOON OVER THE HEADLINE COUNTIES I THROUGH IT BEST TO KEEP THE HEADLINES GOING THROUGH 5 PM. I DO EXPECT THE SUNSHINE TO TURN THIS INTO A MORE CELLULAR EVENT BY LATE THIS MORNING. THAT WILL ONLY HELP BRING THE CONVECTION FARTHER EAST ACROSS THE CWA. ONE WAY OR THE OTHER ONLY OUR EXTREME NORTHEAST AND SOUTHERN COUNTIES WILL HAVE NEGLIGIBLE SNOWFALL THROUGH THE AFTERNOON. PREVIOUS DISCUSSION....THERE WILL BE A BREAK IN THE ACCUMULATION POTENTIAL LATE THIS AFTERNOON AND EARLY THIS EVENING AS THE INVERSION HEIGHTS DROP WITH SHORT WAVE RIDGING ALOFT AND SFC RIDGING MOVING OVERHEAD. THIS WILL BE SHORT LIVED AS A SHORT WAVE OVER NRN ALBERTA THIS MORNING...WILL RACE SE TO ERN WI BY 12Z SAT. MID AND HIGH CLOUDS WILL MOVE IN AHEAD OF THE WAVE...ALLOWING FOR A DEEP LAYER OF MOISTURE OVERHEAD. SNOW IS EXPECTED TO DEVELOP ACROSS THE AREA FROM THE WNW AFTER MIDNIGHT. SW FLOW AHEAD OF THE SYSTEM WILL TRY TO ADVECT SOME WARMER AIR IN...HOWEVER H850 TEMPS ARE EXPECTED TO WARM ONLY TO AROUND -9 TO -10C. PLENTY OF OVER-LAKE INSTABILITY WILL REMAIN AND WILL COMBINE WITH THE SYNOPTIC FORCING TO ENHANCE SNOWFALL ACROSS THE NW CORNER OF THE CWFA. PAST CASES OF A SW FLOW SUCH AS THIS AND A GOOD DEAL OF LOW LEVEL CONVERGENCE...BOTH SUPPORT HEAVIER SNOW ALONG AND NW OF A LINE FROM HOLLAND TO BALDWIN. MODELS SUPPORT A GENERAL 1-3/2-4 INCH TYPE OF EVENT ACROSS MOST OF THE CWFA. WITH THE DEEP MOISTURE... MODERATE OVER-LAKE INSTABILITY...AND THE BEST FORCING CLOSE TO THE DGZ...WARNING CRITERIA SNOWS ARE VERY POSSIBLE OVER THE NW. WE EXPECT THAT AN ADVISORY WILL EVENTUALLY BE NEEDED SURROUNDING THE WATCH AREA. THE WINDOW OF BEST SNOW OVER THE NW LOOKS TO BE AFTER 06Z TONIGHT AND THROUGH 18Z TOMORROW. AFTER 18Z SAT...THE FLOW BECOMES NW BEHIND THE FRONT. ADDITIONAL SNOWS WILL REMAIN POSSIBLE AFTER 18Z AS THE SNOW TRANSITIONS TO LAKE EFFECT. ENOUGH MOISTURE AND A FAVORABLE FLOW WILL KEEP THE POTENTIAL OF ACCUMULATING SNOW IN THROUGH THE EVENING SAT EVENING. AS THE FLOW BECOMES NW...THE SW COUNTIES WILL BEGIN TO SEE LAKE EFFECT TAKE CHARGE. H850 TEMPS WILL FALL BACK DOWN TO AROUND -17C OR SO BY 12Z SUN. INVERSION HEIGHTS ARE EXPECTED TO REMAIN UP THROUGH 10K FEET THROUGH A GOOD PORTION OF SAT NIGHT. THIS COMBINATION WILL BRING POTENTIAL FOR SOME HEAVIER LAKE EFFECT SNOW ACCUMULATIONS SOUTHWEST OF A LINE FROM HOLLAND TO KALAMAZOO. WE CONTEMPLATED ISSUING A WATCH FOR THIS AREA. HOWEVER WITH THE POTENTIAL OF SIGNIFICANT ACCUMS HOLDING OFF UNTIL MAINLY SAT NIGHT...WE FELT IT WAS BEST TO HOLD OFF FOR NOW WITH EVERYTHING ELSE GOING ON. LAKE EFFECT WILL THEN DIMINISH THROUGH THE DAY ON SUNDAY AS THE UPPER TROUGH PULLS AWAY AND SFC RIDGING MOVES IN. && .LONG TERM...(459 AM EST FRI DEC 5 2008) (SUNDAY NIGHT THROUGH THURSDAY) LONG TERM BEGINS WITH HIGH PRESSURE IN PLACE FOR SUNDAY NIGHT. MODELS HAVE SHIFTED SOMEWHAT FOR NEXT WEEK...YIELDING A LESS CONFIDENT FORECAST. FOR THAT REASON DID NOT MAKE MANY CHANGES TO THE GOING FORECAST. MODELS WERE BRINGING A HEALTHY CLIPPER THROUGH THE REGION ON MONDAY...NOW IT IS MORE OF AN INVERTED TROUGH. IN ADDITION...THE STRONG LOW THAT THE GFS WAS ROLLING UP INTO EASTERN CANADA MID WEEK (WHICH WAS TUGGING VERY COLD AIR SOUTH OUT OF CANADA INTO THE GREAT LAKES) IS NO LONGER THERE. TO ADD FURTHER COMPLEXITY...ON THURSDAY MORNING...THE GFS HAS A 1004MB LOW DROPPING OUT OF THE NORTHERN PLAINS...WHEREAS THE EURO HAS A SPRAWLING HIGH BUILDING IN. SUFFICE IT TO SAY CONFIDENCE IS LOW. IT DOES STILL LOOK TO BE A COLDER THAN NORMAL PERIOD...WITH CHANCES AT LAKE EFFECT SNOW. HOPING FOR MORE IN THE WAY OF MODEL CONSISTENCY OFF THE 12Z MODEL RUNS. && .MARINE...(459 AM EST FRI DEC 5 2008) HAVE GONE AHEAD AND HOISTED A GALE WARNING FOR THE PERIOD FROM OVERNIGHT TONIGHT THROUGH MOST OF SATURDAY NIGHT. WINDS REMAIN IN THE 15 TO 25 KNOT RANGE THIS MORNING AT THE OBSERVATION SITES AT BIG SABLE AND THE MUSKEGON GLERL. WINDS WILL PICK UP THIS EVENING AHEAD OF THE INCOMING SYSTEM THAT WILL MOVE THROUGH ON SATURDAY. MODELS INDICATE THAT WE WILL BE ABLE TO MIX A PORTION OF THE 40+ KNOT SOUTHWEST WIND CORE AROUND 2K FEET BEGINNING AFTER 00Z THIS EVENING. THERE MAY BE A BRIEF LULL WHERE WINDS DROP DOWN TO AROUND 25 KNOTS FOR A FEW HOURS ON SAT WHEN THE FRONT COMES THROUGH. HOWEVER NORTHWEST WINDS WILL KICK UP TO GALES ONCE AGAIN AS THE FRONT PASSES AND COLDER AIR ADVECTS IN. FREEZING SPRAY WILL BE POSSIBLE ON SATURDAY NIGHT...HOWEVER WATER TEMPS MAY BE A TAD TOO WARM PER LOCAL STUDIES. THIS CAN BE ADDRESSED MORE BY LATER SHIFTS. && .AVIATION...(1247 PM EST FRI DEC 5 2008) THE LAKE EFFECT SNOW SHOWERS ARE EXPECTED TO VERY SLOWLY DIMINISH TOWARD EVENING AS INVERSION HEIGHTS LOWER AND LIFT WITHIN THE SNOW GROWTH REGION WEAKENS. HOWEVER...IFR OR EVEN PATCHY LIFR WILL PERSIST IN THIS ACTIVITY UNTIL AROUND 02Z. ALSO OF NOTE WILL BE THE BACKING WINDS...FROM WESTERLY TO SOUTHWEST BY EVENING. THIS WILL HELP TAKE THE HEAVIER SNOW SHOWERS AWAY FROM ALL THE TAF SITES EXCEPT MKG BY SUNSET. THERE SHOULD BE A LULL IN THE SNOWFALL FROM MID EVENING UNTIL THE WEE HOURS OF SATURDAY MORNING. HOWEVER BY 08-10Z MORE SNOW WILL MOVE BACK IN AS A CLIPPER SYSTEM MOVES TOWARD THE GREAT LAKES. THIS WILL BRING A BURST OF SNOW TO ALL TAF SITES THROUGH MUCH OF SATURDAY MORNING. THE SNOWFALL WILL PERSIST INTO THE AFTERNOON ALONG THE LAKESHORE AS ANOTHER OF ROUND OF LAKE EFFECT IS GENERATED. && .HYDROLOGY...(459 AM EST FRI DEC 5 2008) NO SIGNIFICANT HYDRO ISSUES IN THE NEXT FEW DAYS AS TEMPERATURES EXPECTED TO GENERALLY BE BELOW FREEZING THROUGH THE NEXT WEEK. LITTLE TO NO RUNOFF CAN BE EXPECTED INTO AREA STREAMS AND RIVERS. IT DOES APPEAR THAT WE WILL BUILD A SNOWPACK WITH LAKE EFFECT SNOW SHOWERS EXPECTED MOST DAYS AND A FEW SYSTEMS MOVING THROUGH. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW WARNING THROUGH 5 PM FOR KENT...OTTAWA AND ALLEGAN COUNTIES. LAKE EFFECT SNOW ADVISORY THROUGH 5 PM FOR BARRY...VAN BUREN AND KALAMAZOO COUNTIES. WINTER STORM WATCH FOR OTTAWA...MUSKEGON...OCEANA...MASON... LAKE...AND NEWAYGO COUNTIES FROM 06Z SAT THROUGH 06Z SUN. LM...SMALL CRAFT ADVISORY IN EFFECT THROUGH 00Z SATURDAY. GALE WARNING IN EFFECT 00Z SATURDAY THROUGH 09Z SUNDAY. && $$ SYNOPSIS: NJJ SHORT TERM: NJJ WDM LONG TERM: DUKE MARINE: NJJ AVIATION: JK HYDROLOGY: NJJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1207 PM EST FRI DEC 5 2008 UPDATED AVIATION DISCUSSION FOR 18Z TAFS .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF CENTERED OVER ERN NAMERICA DOWNWIND OF RDG ALG THE W COAST. CORE OF ARCTIC COLD UNDER THE TROF AT 00Z WAS CENTERED NEAR THE CWA...WITH 00Z H85 TEMP -22C AT INL AND H7 TEMP -25C AT GRB/APX. AT YQD...THE 00Z H8/H7 TEMPS WERE -16C/-19C. OBVIOUSLY WITH THE LARGE AIR/LK SUP WATER TEMP DIFFERENTIAL...QUITE A BIT OF LES HAS BEEN FALLING IN THE FVRD SN BELTS IN THE LLVL WNW FLOW BTWN HI PRES OVER THE CNTRL PLAINS AND LO PRES OVER NRN QUEBEC. MORE WSW LAND BREEZE WIND COMPONENT WITHIN THE RELATIVELY UNMODIFIED ARCTIR AIRMASS OVER LAND APPEARS TO BE INTENSIFYING THE LLVL CNVGC WITH THE MORE NW FLOW OVER THE OPEN WATERS OF LK SUP AND INTENSIFIED THE SRN MOST BANDS STREAMING INTO THE CWA NEAR THE PORCUPINE MTNS AND ALONG THE LK SUP SHORE E OF GRAND MARAIS. PRESENCE OF SOME MID LVL MSTR NOTED BY MID CLD/H85-75 MSTR SHOWN ON THE 00Z INL RAOB ASSOCIATED WITH A PAIR OF SHRTWVS DROPPING SEWD THRU ONTARIO MAY ALSO BE ENHANCING THE BANDS. ANOTHER SHRTWV APPEARS TO BE RIDING OVER THE WRN RDG WITH QUITE A BIT OF MSTR SHOWN ON WV IMAGERY IN ADVANCE OF THIS SYS SPILLING INTO THE NRN PLAINS/MN. MAIN FCST CONCERNS THIS PACKAGE INCLUDE LES TRENDS/COVG/AMTS/GOING HEADLINES THRU TDAY. FOCUS FOR TNGT INTO THE WEEKEND CONCERNS TIMING/IMPACT OF SHRTWV NOW MOVING OVER WRN RDG AND ANOTHER DIGGING SEWD FM NRN CAN. FOR TDAY...HGTS ARE FCST TO RISE SLOWLY OVER THE UPR LKS WITH WARMER AIR TO THE NW GRDLY INFILTRATING THE AREA. IN TANDEM WITH FALLING MSLP OVER SCNTRL CAN AHEAD OF SHRTWV RIDING OVER THE WRN RDG...THE LLVL FLOW IS FCST TO BACK MORE SW. SO LES BANDS WL BEGIN TO DRIFT MORE TO THE N...EXITING ALL BUT THE KEWEENAW BY THE AFTN. MAY BE ABLE TO CANX GOING WRNGS FOR ALGER/LUCE COUNTIES EARLY IF THE BANDS SHIFT N INTO THE LK...WL CHECK RADAR TRENDS AT FCST ISSUANCE. GFS/NAM/LOCAL WRF-ARW RUNS ALSO SUG FLOW WL BACK ENUF TO END HEADLINES FOR THE KEWEENAW EARLY AS WELL. THE FLOW DOES NOT APPEAR TO BACK ENUF TO RAISE CONCERNS ABOUT AN LES BAND OFF LK IMPACTING LUCE/SRN SCHOOLCRAFT COUNTIES. OTRW...LOOKS LIKE ANOTHER DRY COLD DAY OVER THE INTERIOR. BUT HI CLDS NOW SPILLING INTO THE PLAINS/MN WL ARRIVE IN THE AFTN. CONSIDERING THE FRIGID HI TEMPS OBSVD IN THE NRN PLAINS YDAY AND THE LACK OF LK MODERATION WITH BACKING LLVL FLOW...WL TEND TOWARD THE LO END OF MOS GUIANCE FOR HI TEMPS AS SUGD BY GFS FCST SDNGS. TNGT...SW FLOW AHEAD OF SHRTWV NOW TOPPING WRN RDG AND DIGGING SHARPLY SEWD TO IA BY 12Z SAT IS FCST TO DOMINATE. MEANWHILE... ANOTHER SHRTWV MOVING QUICKLY SEWD THRU NW ONTARIO/ASSOCIATED SFC LO AND ARCTIC COLD FNT WL APRCH FM THE NW LATE. EXPECT SOME -SN ASSOCIATED WITH ISENTROPIC LIFT ON THE 275K-285K SFC (H8-65) TO BREAK OUT NW-SE IN ADVANCE OF THESE FEATURES. WITH ABOUT 1.0-1.5 G/KG SPECIFIC HUMIDITY IN THE H7-75 LYR...EXPECT 1 TO 3 INCHES OF -SN TO FALL ACRS THE FA THRU THE NGT. A LAKE ENHANCED SN BAND OFF LK MI IS LIKELY TO DVLP...BUT THE FLOW APPEARS TO HAVE ENUF OF A WLY COMPONENT TO FOCUS THE HEAVIER SN INTO MACKINAC COUNTY SE OF ERY. FAIRLY SHARP DPVA/H85-5 QVECTOR CNVGC IS ALSO FCST TO ARRIVE AFT 06Z AHEAD OF THE NRN SHRTWV. SOME HEAVIER SN MAY DVLP LATE OVER THE W TOWARD 12Z WITH ARRIVAL OF ACCOMPANYING ARCTIC COLD FNT. ALTHOUGH THE TOTAL PCPN APPEARS WL BE RELATIVELY LGT...THE DEEP SATURATION SHOWN ON THE FCST SDNGS SUGS BUMPING UP POPS CLOSER TO THE HIER GFS MOS NUMBERS. SAT LOOKS TO BE A WINTRY DAY WITH BLIZZARD CONDITIONS PSBL FOR AT LEAST A TIME IN THE STRONG NLY FLOW FOLLOWING THE PASSAGE OF CLIPPER LO/ACCOMPANYING COLD FNT. LOCAL WRF-ARW RUN SUGS AN INTENSE SN BAND WL ACCOMPANY THE COLD FROPA...ESPECIALLY OVER THE NRN TIER WHERE THERE WL BE ENHANCEMENT OFF LK SUP/UPSLOPE COMPONENT TO THE NNW FLOW...WITH H925 WINDS PROGGED TO PEAK AT 40 KTS IN THE WAKE OF THE FNT. STRONG WINDS WL LIKELY FRAGMENT THE SN FLAKES THAT WL BECOME INCRSGLY POWDERY WITH ARRIVAL OF COLDER/DRIER AIR IN THE AFTN. THE RESULT WL BE A MORE EFFICIENT REDUCTION IN VSBY. SUSPECT A BLIZZARD WRNG MIGHT BE NECESSARY FOR ALGER COUNTY...WHICH WL BE MOST EXPOSED TO FCST NNW FLOW FOR THE LONGEST PD OF TIME. OTRW...HOISTED WATCH FOR GOGEBIC AND MQT COUNTIES WHILE CONTINUING OTHER GOING WATCHES. ADVYS WL LIKELY BE NECESSARY FOR DELTA/SRN SCHOOLCRAFT ZNS WITH STRG NNW FLOW BLOWING THE LES WELL INLAND.EXPECT MAX TEMPS ON SAT OVER THE W HALF IN THE MRNG...WITH SLOWLY FALLING TEMPS IN THE AFTN. SAT NGT WL FEATURE PURE LES WITH RISING HGTS/DNVA/H85-5 QVECTOR DVGC IN WAKE OF DEPARTING SHRTWV/SFC LO. INTENSITY OF THE LES OVER THE FAR W SHOULD DIMINISH OVERNGT WITH APRCH OF HI PRES RDG/FCST INVRN BASE PROGGED TO SUBSIDE TO ARND H9 BY 12Z SUN AT IWD...BUT EXPECT HI SN/WATER RATIOS UNTIL THE END WITH TEMPS WITHIN THE INCRSGLY SHALLOW MOIST LYR ARND -15C. GOING EXPIRATION OF WATCH FOR THE WRN ZNS SEEMS APPROPRIATE. MAGNITUDE OF THE BLSN SHOULD ALSO DIMINISH W TO E WITH GRDL WEAKENING OF THE PRES GRADIENT W TO E. BUT EXPECTED BLIZZARD CONDITIONS OVER ALGER COUNTY SHOULD LIKELY PERSIST INTO THE EVNG WITH H925 WINDS IN THE 35-40KT RANGE UNTIL ABOUT 03Z. LES WL DIMINISH OVER THE E HALF ON SUN WITH ARRIVAL OF HI PRES RDG. SUN WL BE ANOTHER VERY COLD DAY UNDER ARRIVING RDG AXIS WITH H85 TEMPS IN THE -15C TO -18C RANGE. END OF WATCH LATE ON SUN APPEARS CONSISTENT WITH RECENT GUIDANCE. HI CLDS AHEAD OF YET ANOTHER CLIPPER LO WL INVADE DURING THE DAY. ADDED LO CHC POPS ON SUN NGT TO REFLECT DVLPG ISENTROPIC LIFT/MODEL QPF IN ADVANCE OF THIS CLIPPER. HIEST CHC POPS DOWNWIND OF LK MI WITH SOME MOISTENING/DESTABILATION PSBL OFF THE WATER. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... AT KCMX...LK EFFECT WILL CONTINUE TO LIFT NORTH AND CONDITIONS IMPROVE TO VFR FOR A TIME. NEXT LOW PRES SYSTEM DROPPING INTO THE UPPER LAKES REGION BRINGS MORE SNOW INTO THE REGION BY THIS EVENING. UPSTREAM OBS SUGGEST IFR VSBY WITH THE SNOW...THEN AS ARCTIC FRONT NEARS AND WINDS SHIFT TO NW...HEAVY LK EFFECT MAY RETURN YET AGAIN LATE TONIGHT. CONDITIONS DETERIORATE RAPIDLY TO VLIFR SAT MORNING WITH BLOWING SNOW/SNOW WITH WIND SHIFT AND STRONG WINDS BEHIND THE ARCTIC FRONT AND WILL LOOK TO STAY DOWN ALL DAY. AT KSAW...EXPECT VFR CONDITIONS TO PREVAIL THRU THIS AFTN. MVFR/IFR CONDITIONS DEVELOP IN THE EVENING AS -SN SPREADS INTO THE AREA IN ASSOCIATION WITH APPROACHING LOW PRES SYSTEM. SNOW/WINDS DIMINISH ONLY VERY LATE TONIGHT. CONDITIONS WILL DETERIORATE FROM MVFR LATE SAT MORNING TO VLIFR WITH BLOWING SNOW AND STRONG WINDS BEHIND THE ARCTIC FRONT THAT COME THROUGH SAT MORNING AND WILL LOOK TO STAY LOW FOR A WHILE. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... SW WINDS TODAY MAY REACH GALES BUT SHOULD ONLY BE A FEW GUSTS. ON SATURDAY...STRONG COLD FRONT PLOWING THROUGH WITH DEEPENING SFC LOW LEADS TO HIGH POTENTIAL OF GALES. WENT AHEAD WITH GALE WARNINGS AS CONFIDENCE IS HIGH FOR AT LEAST MARGINAL GALES. STRONG GALES TO 45 KNOTS COULD OCCUR. IF TEMPS GET COLD ENOUGH...COULD SEE NEED FOR FREEZING SPRAY AS WELL. WINDS DIMINISH BY SUNDAY AS HIGH PRESSURE MOVES ACROSS THE GREAT LAKES. SRLY WINDS ON MONDAY NOW LOOK TO STAY BLO GALES. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MIZ003. LAKE EFFECT SNOW ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MIZ001. WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY MORNING FOR MIZ001>003-005-009. WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON FOR MIZ006-007-085. LAKE SUPERIOR... GALE WARNING FROM 10 AM SATURDAY TO 7 AM EST SUNDAY FOR LSZ265>267. GALE WARNING FROM 7 AM TO 10 PM EST SATURDAY FOR LSZ263-264. GALE WARNING FROM 10 AM SATURDAY TO 6 AM EST SUNDAY FOR LSZ248>251. LAKE MICHIGAN... GALE WARNING FROM 7 PM THIS EVENING TO 4 AM EST SUNDAY FOR LMZ248-250. GALE WATCH FROM SATURDAY AFTERNOON THROUGH LATE SATURDAY NIGHT FOR LMZ221. && $$ DISCUSSION...KC AVIATION...GM MARINE...JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1015 AM EST FRI DEC 5 2008 LATEST UPDATE...SHORT TERM AND HEADLINE SECTION... .SYNOPSIS...(459 AM EST FRI DEC 5 2008) LAKE EFFECT SNOW SHOWERS WILL GRADUALLY DIMINISH ACROSS THE AREA DURING THE DAY TODAY AS A PORTION OF A RIDGE OF HIGH PRESSURE MOVES ACROSS THE AREA TODAY. SNOW IS EXPECTED TO INTENSIFY ACROSS THE AREA THEN OVERNIGHT TONIGHT AS AN AREA OF LOW PRESSURE OVER ALBERTA THIS MORNING APPROACHES THE AREA. MOST AREAS WILL SEE AT LEAST A COUPLE OF INCHES OF SNOW FROM TONIGHT THROUGH SATURDAY NIGHT. HEAVIER AMOUNTS OF SNOW ARE LIKELY NORTHWEST OF A LINE FROM HOLLAND TO BALDWIN AS SOUTHWEST WINDS WILL ALLOW LAKE MICHIGAN TO ENHANCE SNOWFALL. && .SHORT TERM...(1015 AM EST FRI DEC 5 2008) (REST OF TODAY THROUGH SUNDAY) I HAVE UPGRADED THE LAKE EFFECT SNOW ADVISORY TO A LAKE EFFECT SNOW WARNING SINCE WE HAVE HAD SEVERAL REPORTS OF BETWEEN 8 TO 10 INCHES IN EXTREME SOUTHWESTERN KENT...EASTERN OTTAWA AND NORTHEAST ALLEGAN COUNTIES IN THE PAST THREE HOURS. ALSO...SINCE THE LATEST RUC SHOWS THE LOW LEVEL WIND CONVERGENCE CONTINUES THROUGH MID AFTERNOON AND SHIFTS NORTH ONLY SLIGHTLY... I EXPECTED THE TIME OF THE HEADLINES UNTIL 5 PM FOR BOTH THE WARNING AND ADVISORY COUNTIES. OUR 88D RADAR CONTINUES TO SHOW ECHO INTENSITIES OVER 30 DBZ CONTINUING TO DEVELOP OVER THE LAKE SHORE AREAS OF OTTAWA AND ALLEGAN COUNTIES THAT THEN MOVE INLAND. GIVEN THE RUC KEEPS THE LIFT AND CONVERGENCE GOING INTO MID AFTERNOON OVER THE HEADLINE COUNTIES I THROUGH IT BEST TO KEEP THE HEADLINES GOING THROUGH 5 PM. I DO EXPECT THE SUNSHINE TO TURN THIS INTO A MORE CELLULAR EVENT BY LATE THIS MORNING. THAT WILL ONLY HELP BRING THE CONVECTION FARTHER EAST ACROSS THE CWA. ONE WAY OR THE OTHER ONLY OUR EXTREME NORTHEAST AND SOUTHERN COUNTIES WILL HAVE NEGLIGIBLE SNOWFALL THROUGH THE AFTERNOON. PREVIOUS DISCUSSION....THERE WILL BE A BREAK IN THE ACCUMULATION POTENTIAL LATE THIS AFTERNOON AND EARLY THIS EVENING AS THE INVERSION HEIGHTS DROP WITH SHORT WAVE RIDGING ALOFT AND SFC RIDGING MOVING OVERHEAD. THIS WILL BE SHORT LIVED AS A SHORT WAVE OVER NRN ALBERTA THIS MORNING...WILL RACE SE TO ERN WI BY 12Z SAT. MID AND HIGH CLOUDS WILL MOVE IN AHEAD OF THE WAVE...ALLOWING FOR A DEEP LAYER OF MOISTURE OVERHEAD. SNOW IS EXPECTED TO DEVELOP ACROSS THE AREA FROM THE WNW AFTER MIDNIGHT. SW FLOW AHEAD OF THE SYSTEM WILL TRY TO ADVECT SOME WARMER AIR IN...HOWEVER H850 TEMPS ARE EXPECTED TO WARM ONLY TO AROUND -9 TO -10C. PLENTY OF OVER-LAKE INSTABILITY WILL REMAIN AND WILL COMBINE WITH THE SYNOPTIC FORCING TO ENHANCE SNOWFALL ACROSS THE NW CORNER OF THE CWFA. PAST CASES OF A SW FLOW SUCH AS THIS AND A GOOD DEAL OF LOW LEVEL CONVERGENCE...BOTH SUPPORT HEAVIER SNOW ALONG AND NW OF A LINE FROM HOLLAND TO BALDWIN. MODELS SUPPORT A GENERAL 1-3/2-4 INCH TYPE OF EVENT ACROSS MOST OF THE CWFA. WITH THE DEEP MOISTURE... MODERATE OVER-LAKE INSTABILITY...AND THE BEST FORCING CLOSE TO THE DGZ...WARNING CRITERIA SNOWS ARE VERY POSSIBLE OVER THE NW. WE EXPECT THAT AN ADVISORY WILL EVENTUALLY BE NEEDED SURROUNDING THE WATCH AREA. THE WINDOW OF BEST SNOW OVER THE NW LOOKS TO BE AFTER 06Z TONIGHT AND THROUGH 18Z TOMORROW. AFTER 18Z SAT...THE FLOW BECOMES NW BEHIND THE FRONT. ADDITIONAL SNOWS WILL REMAIN POSSIBLE AFTER 18Z AS THE SNOW TRANSITIONS TO LAKE EFFECT. ENOUGH MOISTURE AND A FAVORABLE FLOW WILL KEEP THE POTENTIAL OF ACCUMULATING SNOW IN THROUGH THE EVENING SAT EVENING. AS THE FLOW BECOMES NW...THE SW COUNTIES WILL BEGIN TO SEE LAKE EFFECT TAKE CHARGE. H850 TEMPS WILL FALL BACK DOWN TO AROUND -17C OR SO BY 12Z SUN. INVERSION HEIGHTS ARE EXPECTED TO REMAIN UP THROUGH 10K FEET THROUGH A GOOD PORTION OF SAT NIGHT. THIS COMBINATION WILL BRING POTENTIAL FOR SOME HEAVIER LAKE EFFECT SNOW ACCUMULATIONS SOUTHWEST OF A LINE FROM HOLLAND TO KALAMAZOO. WE CONTEMPLATED ISSUING A WATCH FOR THIS AREA. HOWEVER WITH THE POTENTIAL OF SIGNIFICANT ACCUMS HOLDING OFF UNTIL MAINLY SAT NIGHT...WE FELT IT WAS BEST TO HOLD OFF FOR NOW WITH EVERYTHING ELSE GOING ON. LAKE EFFECT WILL THEN DIMINISH THROUGH THE DAY ON SUNDAY AS THE UPPER TROUGH PULLS AWAY AND SFC RIDGING MOVES IN. && .LONG TERM...(459 AM EST FRI DEC 5 2008) (SUNDAY NIGHT THROUGH THURSDAY) LONG TERM BEGINS WITH HIGH PRESSURE IN PLACE FOR SUNDAY NIGHT. MODELS HAVE SHIFTED SOMEWHAT FOR NEXT WEEK...YIELDING A LESS CONFIDENT FORECAST. FOR THAT REASON DID NOT MAKE MANY CHANGES TO THE GOING FORECAST. MODELS WERE BRINGING A HEALTHY CLIPPER THROUGH THE REGION ON MONDAY...NOW IT IS MORE OF AN INVERTED TROUGH. IN ADDITION...THE STRONG LOW THAT THE GFS WAS ROLLING UP INTO EASTERN CANADA MID WEEK (WHICH WAS TUGGING VERY COLD AIR SOUTH OUT OF CANADA INTO THE GREAT LAKES) IS NO LONGER THERE. TO ADD FURTHER COMPLEXITY...ON THURSDAY MORNING...THE GFS HAS A 1004MB LOW DROPPING OUT OF THE NORTHERN PLAINS...WHEREAS THE EURO HAS A SPRAWLING HIGH BUILDING IN. SUFFICE IT TO SAY CONFIDENCE IS LOW. IT DOES STILL LOOK TO BE A COLDER THAN NORMAL PERIOD...WITH CHANCES AT LAKE EFFECT SNOW. HOPING FOR MORE IN THE WAY OF MODEL CONSISTENCY OFF THE 12Z MODEL RUNS. && .MARINE...(459 AM EST FRI DEC 5 2008) HAVE GONE AHEAD AND HOISTED A GALE WARNING FOR THE PERIOD FROM OVERNIGHT TONIGHT THROUGH MOST OF SATURDAY NIGHT. WINDS REMAIN IN THE 15 TO 25 KNOT RANGE THIS MORNING AT THE OBSERVATION SITES AT BIG SABLE AND THE MUSKEGON GLERL. WINDS WILL PICK UP THIS EVENING AHEAD OF THE INCOMING SYSTEM THAT WILL MOVE THROUGH ON SATURDAY. MODELS INDICATE THAT WE WILL BE ABLE TO MIX A PORTION OF THE 40+ KNOT SOUTHWEST WIND CORE AROUND 2K FEET BEGINNING AFTER 00Z THIS EVENING. THERE MAY BE A BRIEF LULL WHERE WINDS DROP DOWN TO AROUND 25 KNOTS FOR A FEW HOURS ON SAT WHEN THE FRONT COMES THROUGH. HOWEVER NORTHWEST WINDS WILL KICK UP TO GALES ONCE AGAIN AS THE FRONT PASSES AND COLDER AIR ADVECTS IN. FREEZING SPRAY WILL BE POSSIBLE ON SATURDAY NIGHT...HOWEVER WATER TEMPS MAY BE A TAD TOO WARM PER LOCAL STUDIES. THIS CAN BE ADDRESSED MORE BY LATER SHIFTS. && .AVIATION...(650 AM EST FRI DEC 5 2008) LAKE EFFECT SNOW SHOWERS CONTINUE THIS MORNING...WITH CONDITIONS VARYING BETWEEN VFR (FLURRIES AND CEILINGS ABOVE 3000FT) AND MVFR (3-5SM -SHSN AND CEILINGS BETWEEN 1000 AND 3000FT). BRIEFLY IN THE HEAVIER SNOW SHOWERS VISIBILITIES WILL DIP BELOW 3SM. EXPECT A GRADUAL DOWNTURN IN SNOW INTENSITY TODAY WITH TAFS SITES MAINLY SEEING VFR CONDITIONS THIS AFTERNOON. THE SNOW SHOWERS SHOULD LOSE BOTH COVERAGE AND INTENSITY THIS AFTERNOON. FOCUS WILL THEN SHIFT TO A CLIPPER SYSTEM DROPPING TOWARD THE GREAT LAKES FROM THE NORTHWEST TONIGHT. A WIDESPREAD LIGHT SNOW WILL MOVE ACROSS THE AREA BETWEEN 06Z AND 12Z. A LAKE ENHANCEMENT IS EXPECTED AT KMKG THOUGH LATE TONIGHT...WHICH WILL DIP VISIBILITIES BELOW A MILE. SIGNIFICANT BLOWING SNOW MAY DEVELOP THERE AS WELL WITH VERY GUSTY SOUTHWEST WINDS. && .HYDROLOGY...(459 AM EST FRI DEC 5 2008) NO SIGNIFICANT HYDRO ISSUES IN THE NEXT FEW DAYS AS TEMPERATURES EXPECTED TO GENERALLY BE BELOW FREEZING THROUGH THE NEXT WEEK. LITTLE TO NO RUNOFF CAN BE EXPECTED INTO AREA STREAMS AND RIVERS. IT DOES APPEAR THAT WE WILL BUILD A SNOWPACK WITH LAKE EFFECT SNOW SHOWERS EXPECTED MOST DAYS AND A FEW SYSTEMS MOVING THROUGH. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW WARNING THROUGH 5 PM FOR KENT...OTTAWA AND ALLEGAN COUNTIES. LAKE EFFECT SNOW ADVISORY THROUGH 5 PM FOR BARRY...VAN BUREN AND KALAMAZOO COUNTIES. WINTER STORM WATCH FOR OTTAWA...MUSKEGON...OCEANA...MASON... LAKE...AND NEWAYGO COUNTIES FROM 06Z SAT THROUGH 06Z SUN. LM...SMALL CRAFT ADVISORY IN EFFECT THROUGH 00Z SATURDAY. GALE WARNING IN EFFECT 00Z SATURDAY THROUGH 09Z SUNDAY. && $$ SYNOPSIS: NJJ SHORT TERM: NJJ WDM LONG TERM: DUKE MARINE: NJJ AVIATION: DUKE HYDROLOGY: NJJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 705 AM EST FRI DEC 5 2008 UPDATED AVIATION DISCUSSION FOR 12Z TAFS .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF CENTERED OVER ERN NAMERICA DOWNWIND OF RDG ALG THE W COAST. CORE OF ARCTIC COLD UNDER THE TROF AT 00Z WAS CENTERED NEAR THE CWA...WITH 00Z H85 TEMP -22C AT INL AND H7 TEMP -25C AT GRB/APX. AT YQD...THE 00Z H8/H7 TEMPS WERE -16C/-19C. OBVIOUSLY WITH THE LARGE AIR/LK SUP WATER TEMP DIFFERENTIAL...QUITE A BIT OF LES HAS BEEN FALLING IN THE FVRD SN BELTS IN THE LLVL WNW FLOW BTWN HI PRES OVER THE CNTRL PLAINS AND LO PRES OVER NRN QUEBEC. MORE WSW LAND BREEZE WIND COMPONENT WITHIN THE RELATIVELY UNMODIFIED ARCTIR AIRMASS OVER LAND APPEARS TO BE INTENSIFYING THE LLVL CNVGC WITH THE MORE NW FLOW OVER THE OPEN WATERS OF LK SUP AND INTENSIFIED THE SRN MOST BANDS STREAMING INTO THE CWA NEAR THE PORCUPINE MTNS AND ALONG THE LK SUP SHORE E OF GRAND MARAIS. PRESENCE OF SOME MID LVL MSTR NOTED BY MID CLD/H85-75 MSTR SHOWN ON THE 00Z INL RAOB ASSOCIATED WITH A PAIR OF SHRTWVS DROPPING SEWD THRU ONTARIO MAY ALSO BE ENHANCING THE BANDS. ANOTHER SHRTWV APPEARS TO BE RIDING OVER THE WRN RDG WITH QUITE A BIT OF MSTR SHOWN ON WV IMAGERY IN ADVANCE OF THIS SYS SPILLING INTO THE NRN PLAINS/MN. MAIN FCST CONCERNS THIS PACKAGE INCLUDE LES TRENDS/COVG/AMTS/GOING HEADLINES THRU TDAY. FOCUS FOR TNGT INTO THE WEEKEND CONCERNS TIMING/IMPACT OF SHRTWV NOW MOVING OVER WRN RDG AND ANOTHER DIGGING SEWD FM NRN CAN. FOR TDAY...HGTS ARE FCST TO RISE SLOWLY OVER THE UPR LKS WITH WARMER AIR TO THE NW GRDLY INFILTRATING THE AREA. IN TANDEM WITH FALLING MSLP OVER SCNTRL CAN AHEAD OF SHRTWV RIDING OVER THE WRN RDG...THE LLVL FLOW IS FCST TO BACK MORE SW. SO LES BANDS WL BEGIN TO DRIFT MORE TO THE N...EXITING ALL BUT THE KEWEENAW BY THE AFTN. MAY BE ABLE TO CANX GOING WRNGS FOR ALGER/LUCE COUNTIES EARLY IF THE BANDS SHIFT N INTO THE LK...WL CHECK RADAR TRENDS AT FCST ISSUANCE. GFS/NAM/LOCAL WRF-ARW RUNS ALSO SUG FLOW WL BACK ENUF TO END HEADLINES FOR THE KEWEENAW EARLY AS WELL. THE FLOW DOES NOT APPEAR TO BACK ENUF TO RAISE CONCERNS ABOUT AN LES BAND OFF LK IMPACTING LUCE/SRN SCHOOLCRAFT COUNTIES. OTRW...LOOKS LIKE ANOTHER DRY COLD DAY OVER THE INTERIOR. BUT HI CLDS NOW SPILLING INTO THE PLAINS/MN WL ARRIVE IN THE AFTN. CONSIDERING THE FRIGID HI TEMPS OBSVD IN THE NRN PLAINS YDAY AND THE LACK OF LK MODERATION WITH BACKING LLVL FLOW...WL TEND TOWARD THE LO END OF MOS GUIANCE FOR HI TEMPS AS SUGD BY GFS FCST SDNGS. TNGT...SW FLOW AHEAD OF SHRTWV NOW TOPPING WRN RDG AND DIGGING SHARPLY SEWD TO IA BY 12Z SAT IS FCST TO DOMINATE. MEANWHILE... ANOTHER SHRTWV MOVING QUICKLY SEWD THRU NW ONTARIO/ASSOCIATED SFC LO AND ARCTIC COLD FNT WL APRCH FM THE NW LATE. EXPECT SOME -SN ASSOCIATED WITH ISENTROPIC LIFT ON THE 275K-285K SFC (H8-65) TO BREAK OUT NW-SE IN ADVANCE OF THESE FEATURES. WITH ABOUT 1.0-1.5 G/KG SPECIFIC HUMIDITY IN THE H7-75 LYR...EXPECT 1 TO 3 INCHES OF -SN TO FALL ACRS THE FA THRU THE NGT. A LAKE ENHANCED SN BAND OFF LK MI IS LIKELY TO DVLP...BUT THE FLOW APPEARS TO HAVE ENUF OF A WLY COMPONENT TO FOCUS THE HEAVIER SN INTO MACKINAC COUNTY SE OF ERY. FAIRLY SHARP DPVA/H85-5 QVECTOR CNVGC IS ALSO FCST TO ARRIVE AFT 06Z AHEAD OF THE NRN SHRTWV. SOME HEAVIER SN MAY DVLP LATE OVER THE W TOWARD 12Z WITH ARRIVAL OF ACCOMPANYING ARCTIC COLD FNT. ALTHOUGH THE TOTAL PCPN APPEARS WL BE RELATIVELY LGT...THE DEEP SATURATION SHOWN ON THE FCST SDNGS SUGS BUMPING UP POPS CLOSER TO THE HIER GFS MOS NUMBERS. SAT LOOKS TO BE A WINTRY DAY WITH BLIZZARD CONDITIONS PSBL FOR AT LEAST A TIME IN THE STRONG NLY FLOW FOLLOWING THE PASSAGE OF CLIPPER LO/ACCOMPANYING COLD FNT. LOCAL WRF-ARW RUN SUGS AN INTENSE SN BAND WL ACCOMPANY THE COLD FROPA...ESPECIALLY OVER THE NRN TIER WHERE THERE WL BE ENHANCEMENT OFF LK SUP/UPSLOPE COMPONENT TO THE NNW FLOW...WITH H925 WINDS PROGGED TO PEAK AT 40 KTS IN THE WAKE OF THE FNT. STRONG WINDS WL LIKELY FRAGMENT THE SN FLAKES THAT WL BECOME INCRSGLY POWDERY WITH ARRIVAL OF COLDER/DRIER AIR IN THE AFTN. THE RESULT WL BE A MORE EFFICIENT REDUCTION IN VSBY. SUSPECT A BLIZZARD WRNG MIGHT BE NECESSARY FOR ALGER COUNTY...WHICH WL BE MOST EXPOSED TO FCST NNW FLOW FOR THE LONGEST PD OF TIME. OTRW...HOISTED WATCH FOR GOGEBIC AND MQT COUNTIES WHILE CONTINUING OTHER GOING WATCHES. ADVYS WL LIKELY BE NECESSARY FOR DELTA/SRN SCHOOLCRAFT ZNS WITH STRG NNW FLOW BLOWING THE LES WELL INLAND.EXPECT MAX TEMPS ON SAT OVER THE W HALF IN THE MRNG...WITH SLOWLY FALLING TEMPS IN THE AFTN. SAT NGT WL FEATURE PURE LES WITH RISING HGTS/DNVA/H85-5 QVECTOR DVGC IN WAKE OF DEPARTING SHRTWV/SFC LO. INTENSITY OF THE LES OVER THE FAR W SHOULD DIMINISH OVERNGT WITH APRCH OF HI PRES RDG/FCST INVRN BASE PROGGED TO SUBSIDE TO ARND H9 BY 12Z SUN AT IWD...BUT EXPECT HI SN/WATER RATIOS UNTIL THE END WITH TEMPS WITHIN THE INCRSGLY SHALLOW MOIST LYR ARND -15C. GOING EXPIRATION OF WATCH FOR THE WRN ZNS SEEMS APPROPRIATE. MAGNITUDE OF THE BLSN SHOULD ALSO DIMINISH W TO E WITH GRDL WEAKENING OF THE PRES GRADIENT W TO E. BUT EXPECTED BLIZZARD CONDITIONS OVER ALGER COUNTY SHOULD LIKELY PERSIST INTO THE EVNG WITH H925 WINDS IN THE 35-40KT RANGE UNTIL ABOUT 03Z. LES WL DIMINISH OVER THE E HALF ON SUN WITH ARRIVAL OF HI PRES RDG. SUN WL BE ANOTHER VERY COLD DAY UNDER ARRIVING RDG AXIS WITH H85 TEMPS IN THE -15C TO -18C RANGE. END OF WATCH LATE ON SUN APPEARS CONSISTENT WITH RECENT GUIDANCE. HI CLDS AHEAD OF YET ANOTHER CLIPPER LO WL INVADE DURING THE DAY. ADDED LO CHC POPS ON SUN NGT TO REFLECT DVLPG ISENTROPIC LIFT/MODEL QPF IN ADVANCE OF THIS CLIPPER. HIEST CHC POPS DOWNWIND OF LK MI WITH SOME MOISTENING/DESTABILATION PSBL OFF THE WATER. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... AT KCMX...LK EFFECT -SHSN WILL CONTINUE THROUGH THE MORNING. WINDS BACKING SW ENHANCE LOW-LEVEL CONVERGENCE THROUGH MID MORNING AND EXPECT CONDITIONS TO FLUCTUATE BTWN LIFR AND VLIFR IN THE HEAVIER SHSN. BY AFTN...LK EFFECT LIFTS NORTH OF CMX AND CONDITIONS IMPROVE TO VFR FOR A TIME. NEXT LOW PRES SYSTEM DROPPING INTO THE UPPER LAKES REGION BRINGS MORE SNOW INTO THE REGION BY THIS EVENING. UPSTREAM OBS SUGGEST IFR VSBY WITH THE SNOW...THEN AS ARCTIC FRONT NEARS AND WINDS SHIFT TO NW...HEAVY LK EFFECT MAY RETURN YET AGAIN LATE TONIGHT. AT KSAW...EXPECT VFR CONDITIONS TO PREVAIL THRU THIS AFTN. WINDS WILL BEGIN TO GUST ABOVE 20 KT BY LATE AFTN. MVFR/IFR CONDITIONS DEVELOP IN THE EVENING AS -SN SPREADS INTO THE AREA IN ASSOCIATION WITH APPROACHING LOW PRES SYSTEM. SNOW/WINDS DIMINISH ONLY VERY LATE TONIGHT. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... SW WINDS TODAY MAY REACH GALES BUT SHOULD ONLY BE A FEW GUSTS. ON SATURDAY...STRONG COLD FRONT PLOWING THROUGH WITH DEEPENING SFC LOW LEADS TO HIGH POTENTIAL OF GALES. WENT AHEAD WITH GALE WARNINGS AS CONFIDENCE IS HIGH FOR AT LEAST MARGINAL GALES. STRONG GALES TO 45 KNOTS COULD OCCUR. IF TEMPS GET COLD ENOUGH...COULD SEE NEED FOR FREEZING SPRAY AS WELL. WINDS DIMINISH BY SUNDAY AS HIGH PRESSURE MOVES ACROSS THE GREAT LAKES. SRLY WINDS ON MONDAY NOW LOOK TO STAY BLO GALES. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW WARNING UNTIL 7 AM EST THIS MORNING FOR MIZ002. LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MIZ003. LAKE EFFECT SNOW ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MIZ001. WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY MORNING FOR MIZ001>003-005-009. WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON FOR MIZ006-007-085. LAKE SUPERIOR... GALE WARNING FROM 10 AM SATURDAY TO 7 AM EST SUNDAY FOR LSZ265>267. GALE WARNING FROM 7 AM TO 10 PM EST SATURDAY FOR LSZ263-264. GALE WARNING FROM 10 AM SATURDAY TO 6 AM EST SUNDAY FOR LSZ248>251. LAKE MICHIGAN... GALE WARNING FROM 7 PM THIS EVENING TO 4 AM EST SUNDAY FOR LMZ248-250. GALE WATCH FROM SATURDAY AFTERNOON THROUGH LATE SATURDAY NIGHT FOR LMZ221. && $$ DISCUSSION...KC AVIATION...JLA MARINE...JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 455 AM EST FRI DEC 5 2008 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF CENTERED OVER ERN NAMERICA DOWNWIND OF RDG ALG THE W COAST. CORE OF ARCTIC COLD UNDER THE TROF AT 00Z WAS CENTERED NEAR THE CWA...WITH 00Z H85 TEMP -22C AT INL AND H7 TEMP -25C AT GRB/APX. AT YQD...THE 00Z H8/H7 TEMPS WERE -16C/-19C. OBVIOUSLY WITH THE LARGE AIR/LK SUP WATER TEMP DIFFERENTIAL...QUITE A BIT OF LES HAS BEEN FALLING IN THE FVRD SN BELTS IN THE LLVL WNW FLOW BTWN HI PRES OVER THE CNTRL PLAINS AND LO PRES OVER NRN QUEBEC. MORE WSW LAND BREEZE WIND COMPONENT WITHIN THE RELATIVELY UNMODIFIED ARCTIR AIRMASS OVER LAND APPEARS TO BE INTENSIFYING THE LLVL CNVGC WITH THE MORE NW FLOW OVER THE OPEN WATERS OF LK SUP AND INTENSIFIED THE SRN MOST BANDS STREAMING INTO THE CWA NEAR THE PORCUPINE MTNS AND ALONG THE LK SUP SHORE E OF GRAND MARAIS. PRESENCE OF SOME MID LVL MSTR NOTED BY MID CLD/H85-75 MSTR SHOWN ON THE 00Z INL RAOB ASSOCIATED WITH A PAIR OF SHRTWVS DROPPING SEWD THRU ONTARIO MAY ALSO BE ENHANCING THE BANDS. ANOTHER SHRTWV APPEARS TO BE RIDING OVER THE WRN RDG WITH QUITE A BIT OF MSTR SHOWN ON WV IMAGERY IN ADVANCE OF THIS SYS SPILLING INTO THE NRN PLAINS/MN. MAIN FCST CONCERNS THIS PACKAGE INCLUDE LES TRENDS/COVG/AMTS/GOING HEADLINES THRU TDAY. FOCUS FOR TNGT INTO THE WEEKEND CONCERNS TIMING/IMPACT OF SHRTWV NOW MOVING OVER WRN RDG AND ANOTHER DIGGING SEWD FM NRN CAN. FOR TDAY...HGTS ARE FCST TO RISE SLOWLY OVER THE UPR LKS WITH WARMER AIR TO THE NW GRDLY INFILTRATING THE AREA. IN TANDEM WITH FALLING MSLP OVER SCNTRL CAN AHEAD OF SHRTWV RIDING OVER THE WRN RDG...THE LLVL FLOW IS FCST TO BACK MORE SW. SO LES BANDS WL BEGIN TO DRIFT MORE TO THE N...EXITING ALL BUT THE KEWEENAW BY THE AFTN. MAY BE ABLE TO CANX GOING WRNGS FOR ALGER/LUCE COUNTIES EARLY IF THE BANDS SHIFT N INTO THE LK...WL CHECK RADAR TRENDS AT FCST ISSUANCE. GFS/NAM/LOCAL WRF-ARW RUNS ALSO SUG FLOW WL BACK ENUF TO END HEADLINES FOR THE KEWEENAW EARLY AS WELL. THE FLOW DOES NOT APPEAR TO BACK ENUF TO RAISE CONCERNS ABOUT AN LES BAND OFF LK IMPACTING LUCE/SRN SCHOOLCRAFT COUNTIES. OTRW...LOOKS LIKE ANOTHER DRY COLD DAY OVER THE INTERIOR. BUT HI CLDS NOW SPILLING INTO THE PLAINS/MN WL ARRIVE IN THE AFTN. CONSIDERING THE FRIGID HI TEMPS OBSVD IN THE NRN PLAINS YDAY AND THE LACK OF LK MODERATION WITH BACKING LLVL FLOW...WL TEND TOWARD THE LO END OF MOS GUIANCE FOR HI TEMPS AS SUGD BY GFS FCST SDNGS. TNGT...SW FLOW AHEAD OF SHRTWV NOW TOPPING WRN RDG AND DIGGING SHARPLY SEWD TO IA BY 12Z SAT IS FCST TO DOMINATE. MEANWHILE... ANOTHER SHRTWV MOVING QUICKLY SEWD THRU NW ONTARIO/ASSOCIATED SFC LO AND ARCTIC COLD FNT WL APRCH FM THE NW LATE. EXPECT SOME -SN ASSOCIATED WITH ISENTROPIC LIFT ON THE 275K-285K SFC (H8-65) TO BREAK OUT NW-SE IN ADVANCE OF THESE FEATURES. WITH ABOUT 1.0-1.5 G/KG SPECIFIC HUMIDITY IN THE H7-75 LYR...EXPECT 1 TO 3 INCHES OF -SN TO FALL ACRS THE FA THRU THE NGT. A LAKE ENHANCED SN BAND OFF LK MI IS LIKELY TO DVLP...BUT THE FLOW APPEARS TO HAVE ENUF OF A WLY COMPONENT TO FOCUS THE HEAVIER SN INTO MACKINAC COUNTY SE OF ERY. FAIRLY SHARP DPVA/H85-5 QVECTOR CNVGC IS ALSO FCST TO ARRIVE AFT 06Z AHEAD OF THE NRN SHRTWV. SOME HEAVIER SN MAY DVLP LATE OVER THE W TOWARD 12Z WITH ARRIVAL OF ACCOMPANYING ARCTIC COLD FNT. ALTHOUGH THE TOTAL PCPN APPEARS WL BE RELATIVELY LGT...THE DEEP SATURATION SHOWN ON THE FCST SDNGS SUGS BUMPING UP POPS CLOSER TO THE HIER GFS MOS NUMBERS. SAT LOOKS TO BE A WINTRY DAY WITH BLIZZARD CONDITIONS PSBL FOR AT LEAST A TIME IN THE STRONG NLY FLOW FOLLOWING THE PASSAGE OF CLIPPER LO/ACCOMPANYING COLD FNT. LOCAL WRF-ARW RUN SUGS AN INTENSE SN BAND WL ACCOMPANY THE COLD FROPA...ESPECIALLY OVER THE NRN TIER WHERE THERE WL BE ENHANCEMENT OFF LK SUP/UPSLOPE COMPONENT TO THE NNW FLOW...WITH H925 WINDS PROGGED TO PEAK AT 40 KTS IN THE WAKE OF THE FNT. STRONG WINDS WL LIKELY FRAGMENT THE SN FLAKES THAT WL BECOME INCRSGLY POWDERY WITH ARRIVAL OF COLDER/DRIER AIR IN THE AFTN. THE RESULT WL BE A MORE EFFICIENT REDUCTION IN VSBY. SUSPECT A BLIZZARD WRNG MIGHT BE NECESSARY FOR ALGER COUNTY...WHICH WL BE MOST EXPOSED TO FCST NNW FLOW FOR THE LONGEST PD OF TIME. OTRW...HOISTED WATCH FOR GOGEBIC AND MQT COUNTIES WHILE CONTINUING OTHER GOING WATCHES. ADVYS WL LIKELY BE NECESSARY FOR DELTA/SRN SCHOOLCRAFT ZNS WITH STRG NNW FLOW BLOWING THE LES WELL INLAND.EXPECT MAX TEMPS ON SAT OVER THE W HALF IN THE MRNG...WITH SLOWLY FALLING TEMPS IN THE AFTN. SAT NGT WL FEATURE PURE LES WITH RISING HGTS/DNVA/H85-5 QVECTOR DVGC IN WAKE OF DEPARTING SHRTWV/SFC LO. INTENSITY OF THE LES OVER THE FAR W SHOULD DIMINISH OVERNGT WITH APRCH OF HI PRES RDG/FCST INVRN BASE PROGGED TO SUBSIDE TO ARND H9 BY 12Z SUN AT IWD...BUT EXPECT HI SN/WATER RATIOS UNTIL THE END WITH TEMPS WITHIN THE INCRSGLY SHALLOW MOIST LYR ARND -15C. GOING EXPIRATION OF WATCH FOR THE WRN ZNS SEEMS APPROPRIATE. MAGNITUDE OF THE BLSN SHOULD ALSO DIMINISH W TO E WITH GRDL WEAKENING OF THE PRES GRADIENT W TO E. BUT EXPECTED BLIZZARD CONDITIONS OVER ALGER COUNTY SHOULD LIKELY PERSIST INTO THE EVNG WITH H925 WINDS IN THE 35-40KT RANGE UNTIL ABOUT 03Z. LES WL DIMINISH OVER THE E HALF ON SUN WITH ARRIVAL OF HI PRES RDG. SUN WL BE ANOTHER VERY COLD DAY UNDER ARRIVING RDG AXIS WITH H85 TEMPS IN THE -15C TO -18C RANGE. END OF WATCH LATE ON SUN APPEARS CONSISTENT WITH RECENT GUIDANCE. HI CLDS AHEAD OF YET ANOTHER CLIPPER LO WL INVADE DURING THE DAY. ADDED LO CHC POPS ON SUN NGT TO REFLECT DVLPG ISENTROPIC LIFT/MODEL QPF IN ADVANCE OF THIS CLIPPER. HIEST CHC POPS DOWNWIND OF LK MI WITH SOME MOISTENING/DESTABILATION PSBL OFF THE WATER. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... WITH LAKE EFFECT -SHSN CONTINUING AT KCMX...EXPECT CONDITIONS TO VARY BTWN IFR AND LIFR THRU THE MORNING. THERE MAY BE SOME BRIEF PERIODS OF MVFR AND PERHAPS VFR...BUT THOSE PERIODS WILL BE VERY INFREQUENT. AS WINDS BACK MORE TO THE SW VERY LATE IN THE NIGHT INTO THE MORNING...ENHANCING LOW-LEVEL CONVERGENCE...EXPECT A PREVAILING PERIOD OF VLIFR CONDITIONS IN HEAVIER SHSN. AS WINDS CONTINUE TO BACK...EXPECT CONDITIONS TO IMPROVE TO MVFR LATE MORNING AND TO VFR IN THE AFTN. NEXT LOW PRES SYSTEM DROPPING INTO THE UPPER LAKES REGION WILL BRING A RETURN TO MVFR CONDITIONS WITH -SN DURING THE EVENING. AT KSAW...WITH LOW-LEVEL W TO SW WINDS...LAKE EFFECT -SHSN WILL NOT BE AN ISSUE. EXPECT VFR CONDITIONS TO PREVAIL OVERNIGHT THRU THE AFTN. MVFR CONDITIONS SHOULD DEVELOP IN THE EVENING AS -SN SPREADS INTO THE AREA IN ASSOCIATION WITH APPROACHING LOW PRES SYSTEM. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... SW WINDS TODAY MAY REACH GALES BUT SHOULD ONLY BE A FEW GUSTS. ON SATURDAY...STRONG COLD FRONT PLOWING THROUGH WITH DEEPENING SFC LOW LEADS TO HIGH POTENTIAL OF GALES. WENT AHEAD WITH GALE WARNINGS AS CONFIDENCE IS HIGH FOR AT LEAST MARGINAL GALES. STRONG GALES TO 45 KNOTS COULD OCCUR. IF TEMPS GET COLD ENOUGH...COULD SEE NEED FOR FREEZING SPRAY AS WELL. WINDS DIMINISH BY SUNDAY AS HIGH PRESSURE MOVES ACROSS THE GREAT LAKES. SRLY WINDS ON MONDAY NOW LOOK TO STAY BLO GALES. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW WARNING UNTIL 7 AM EST THIS MORNING FOR MIZ002. LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MIZ003. LAKE EFFECT SNOW ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MIZ001. WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY MORNING FOR MIZ001>003-005-009. WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON FOR MIZ006-007-085. LAKE SUPERIOR... GALE WARNING FROM 10 AM SATURDAY TO 7 AM EST SUNDAY FOR LSZ265>267. GALE WARNING FROM 7 AM TO 10 PM EST SATURDAY FOR LSZ263-264. GALE WARNING FROM 10 AM SATURDAY TO 6 AM EST SUNDAY FOR LSZ248>251. LAKE MICHIGAN... GALE WARNING FROM 7 PM THIS EVENING TO 4 AM EST SUNDAY FOR LMZ248-250. GALE WATCH FROM SATURDAY AFTERNOON THROUGH LATE SATURDAY NIGHT FOR LMZ221. && $$ DISCUSSION...KC AVIATION...JLA MARINE...JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1243 PM EST THU DEC 4 2008 LATEST UPDATE...AVIATION... .SYNOPSIS...(412 AM EST THU DEC 4 2008) COLDER AIR WILL CONTINUE MOVING IN OVER THE GREAT LAKES INTO THE DAY ON FRIDAY. THIS WILL ALLOW FOR LAKE EFFECT SNOW SHOWERS TO BE EXPECTED RIGHT ON THROUGH THE REMAINDER OF THE WEEK. SIGNIFICANT AMOUNTS OF LAKE EFFECT ARE NOT EXPECTED...HOWEVER SOME AREAS WILL SEE THE SNOWPACK GRADUALLY BUILD. AN AREA OF LOW PRESSURE WILL MOVE IN ACROSS THE REGION LATE FRIDAY NIGHT AND DURING THE DAY ON SATURDAY. THIS SYSTEM WILL BRING SOME SNOW TO MOST OF THE AREA...WITH LAKE ENHANCEMENT INCREASING AMOUNTS A BIT ALONG MOST OF THE LAKESHORE. && .SHORT TERM...(1040 AM EST THU DEC 4 2008) (REST OF TODAY THROUGH SATURDAY) I HAVE UPDATED THE FORECAST TO INCREASE THE AREA OF CONDITIONAL POP THROUGH THIS AFTERNOON. I ALSO INCREASED THE FORECAST SNOWFALL AMOUNTS FOR TODAY TO 1 TO 2 INCHES CENTERED ON US-131. THAT WAS BASED ON RADAR TRENDS AND THE IR AND WATER VAPOR IMAGES CONFIRMING WHAT THE 12Z RUC SUGGESTS.... THAT IS CORE OF THE POLAR JET HAS PASSED EAST OF THE SOUTHWEST MICHIGAN. WITH THE VAD WIND SUGGESTS THE INVERSION HEIGHT HAS INCREASED ABOUT 1000 FT FROM 5000 FT PRIOR TO 14Z TO ABOUT 6000 FT AT 15Z. TAMDAR SOUNDINGS SHOWS SIMILAR TRENDS. 850 MB TEMP CONTINUES TO FALL FROM AROUND -13C AT 12Z OVER LAKE MICHIGAN TO NEAR -15C BY 18Z. SFC OBS SHOW 1TO MILE VIS AT GRR LAN AZO RQB AT 15Z. ALSO THE RUC SHOWS THE DGZ HAS BECOME SATURATED AND WILL REMAIN SO THE REST OF THE DAY. THE BEST LIFT IS BETWEEN NOW AND 20Z. THE MEAN BOUNDARY LAYER WIND IS 270 DEGREES AROUND 25 KNOTS. THUS I BELIEVE WE WILL SEE SNOW ALL DAY OVER MOST OF THE CWA DOWN WIND OF LAKE MICHIGAN BETWEEN ROUTE 10 AND I-94. SOUTH OF I-94 WINDS ARE NOT OVER THE LAKE LONG ENOUGH TO REALLY DO MUCH IN TERMS OF SNOWFALL. NEXT SPEED MAX/SHORT WAVE TROUGH IS NOW DIVING SOUTHEAST OVER THE DAKOTAS AND MN. THIS SYSTEM WILL BE ENOUGH TO SEND THE POLAR JET SOUTH OF THE AREA TONIGHT. WITH THE APPROACH OF THE UPPER SYSTEMS....INVERSION HTS ARE EXPECTED TO INCREASE TO AROUND 8-9K FT. LOW LEVEL FLOW IS EXPECTED TO REMAIN MAINLY WNW THROUGH THE NIGHT. THE SYNOPTIC FORCING IN ADDITION TO THE FAVORABLE OVER-LAKE INSTABILITY WILL INCREASE THE INTENSITY OF THE SNOW SHOWERS. MODELS ARE INDICATING THAT A GOOD DEAL OF LOW LEVEL CONVERGENCE WILL DEVELOP LATE THIS EVENING AND LAST INTO THE OVERNIGHT HOURS. THE FAVORED AREAS WILL BE ROUGHLY SOUTH OF A LINE FROM GRAND HAVEN TO CHARLOTTE. THE LIMITED INVERSION HTS SHOULD KEEP THIS PICKUP IN LAKE EFFECT FROM GETTING TOO OUT OF HAND. WE DO NOT HAVE THE CONFIDENCE ANY LOCATION WILL SEE WARNING CRITERIA ACCUMS...HOWEVER WE DO BELIEVE THERE IS A GOOD CHANCE THAT AN ADVISORY MAY BE NEEDED. WE HAVE TRENDED AMOUNTS UP...AND ENOUGH TIME EXISTS THAT THE DAY SHIFT CAN TAKE ANOTHER LOOK AT POSSIBLE HEADLINES. INVERSION HTS WILL FALL A BIT AS THE SHORT WAVE MOVES AWAY FROM THE AREA ON FRI MORNING. WINDS ARE EXPECTED TO SHIFT FROM THE WNW TO MORE SW BY LATE FRI AFTERNOON. THIS WILL HELP TO KEEP ANY ONE AREA FROM SEEING MUCH SNOW. THE FOCUS OF BETTER SNOW ACCUMS WILL TRANSITION FROM THE SW CORNER OF THE CWFA TO THE NW CORNER. THE NEXT COUPLE OF SHORT WAVES WILL THEN DIVE SE TOWARD THE AREA LATE FRI NIGHT AND DURING THE DAY ON SAT. IT WILL BE THE SECOND SHORT WAVE THAT WILL BRING A CLIPPER TYPE SFC LOW ACROSS THE NRN PORTION OF THE STATE. THE SYSTEM ITSELF WILL BE POTENT...AND WOULD BRING A COUPLE OF INCHES OF SNOW BY ITSELF. H850 TEMPS DO NOT WARM ALL THAT MUCH AHEAD OF IT...LEAVING DELTA T/S AT LEAST IN THE MID TEENS ACROSS THE AREA. THE SW FLOW COMBINED WITH ALMOST A NON-EXISTENT INVERSION AND THE OVER-LAKE INSTABILITY WILL SET UP WHAT LOOKS TO BE A POTENTIALLY SIGNIFICANT LAKE ENHANCEMENT EVENT FOR THE NW PORTION OF THE CWFA. SOME DETAILS WILL NEED TO BE WORKED OUT...BUT THERE IS POTENTIAL FOR SOME WARNING CRITERIA SNOWS. THIS WILL BE LATE 4TH PERIOD/5TH PERIOD...SO WE WILL HOLD OFF ON ANY WATCH FOR NOW. && .LONG TERM...(412 AM EST THU DEC 4 2008) (SATURDAY NIGHT THROUGH WEDNESDAY) MAIN STORY IN THE LONG TERM WILL BE SNOW AND COLD. SURGES OF COLD AIR WILL PUSH INTO SOUTHWEST LOWER MICHIGAN DURING WEEKEND AND INTO THE MIDDLE OF NEXT WEEK. THE FIRST SURGE WILL RUSH IN SATURDAY NIGHT IN THE WAKE OF A CLIPPER SYSTEM MOVING OFF TO THE EAST. 850MB TEMPS ARE FORECAST TO PLUNGE INTO THE MIDDLE TEENS C BELOW ZERO. LAKE EFFECT WILL CONTINUE INTO SUNDAY...BEFORE RIDGING ENDS MUCH OF THE ACTIVITY INTO SUNDAY NIGHT. ANOTHER CLIPPER WILL MOVE THROUGH THE REGION MONDAY AND MONDAY NIGHT. THE ASSOCIATED COLD FRONT PUSHES THROUGH THE AREA TUESDAY MORNING. ARCTIC AIR POURS INTO THE GREAT LAKES REGION INTO MID WEEK...WITH 850MB TEMPS PLUNGING WELL INTO THE 20S BELOW ZERO C. SOME SYNOPTIC SCALE SNOW CAN BE EXPECTED MONDAY AND MONDAY NIGHT AS THE SYSTEM MOVES THROUGH...FOLLOWED BY GOOD CHANCES FOR LAKE EFFECT TUESDAY INTO WEDNESDAY. TRIED TO NUDGE DOWN TEMPS IN THE EXTENDED...GIVEN WHAT HAS BEEN A PERSISTENT SIGNAL BY THE GFS TO FORECAST A COLD PERIOD. TEMPERATURES FOR THE MIDDLE OF NEXT WEEK MAY VERY WELL BE DEEP WINTER TYPE NUMBERS WITH HIGHS IN THE TEENS AND LOWS DIPPING TOWARD ZERO. DID NOT GO THAT COLD YET...BUT HAVE BEGUN THE TREND IN THAT DIRECTION. && .MARINE...(1040 AM EST THU DEC 4 2008) I EXTENDED THE SCA UNTIL 00Z SATURDAY SINCE THE WINDS AND WAVES ARE MORE THAN STRONG AND OR LARGE ENOUGH. WE MAY END UP WITH A GALE WARNING FOR LATE FRIDAY NIGHT ON LATER FORECASTS DUE THE STRONG SYSTEM COMING IN FROM THE NORTHWEST FOR SATURDAY. FREEZING SPRAY POTENTIAL WILL INCREASE AT THAT TIME WITH COLDER AIR MOVING IN. && .AVIATION...(1243 PM EST THU DEC 4 2008) LAKE EFFECT SNOW SHOWERS PERSIST EARLY THIS AFTERNOON. TEMPERATURE INVERSION HEIGHTS CLIMB TOWARD EVENING AND LIFT INCREASES AS AN UPPER LEVEL DISTURBANCE WILL FURTHER ENHANCE THE SNOW SHOWERS. IT APPEARS THE LAKE EFFECT SHOULD GET FAIRLY INTENSE BETWEEN 22Z AND 06Z WITH LIFR LIKELY WITHIN THE HEAVIER SNOW SHOWERS. BEYOND 06Z THE SHORT WAVE WILL BE THROUGH AND THE LAKE EFFECT IS EXPECTED TO DIMINISH SLIGHTLY. THERE COULD BE A DIURNAL COMPONENT TO THIS ACTIVITY ALSO WITH SOME INTENSIFICATION POSSIBLE TOWARD SUNRISE ON FRIDAY. AT THIS POINT IT APPEARS THE SNOW SHOWERS SHOULD DIMINISH THEN BY MID/LATE FRIDAY MORNING. WIND FLOW THROUGH THE NEXT 24 HOURS WILL BE WNW WHICH WILL FAVOR AZO AND GRR GETTING MORE FREQUENT SNOW SHOWERS...HOWEVER THE REMAINING TAF SITES WILL ALSO SEE OCCASIONAL SNOW SHOWERS WITH IFR CONDITIONS. && .HYDROLOGY...(412 AM EST THU DEC 4 2008) WITH TEMPERATURES EXPECTED TO GENERALLY BE BELOW FREEZING THROUGH THE NEXT WEEK...LITTLE TO NO RUNOFF CAN BE EXPECTED INTO AREA STREAMS AND RIVERS. IT DOES APPEAR THAT WE WILL BUILD A SNOWPACK WITH LAKE EFFECT SNOW SHOWERS EXPECTED MOST DAYS AND A FEW SYSTEMS MOVING THROUGH. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY IN EFFECT THROUGH 00Z SATURDAY. && $$ SYNOPSIS: NJJ SHORT TERM: NJJ / WDM LONG TERM: DUKE MARINE: NJJ / WDM AVIATION: JK HYDROLOGY: NJJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1040 AM EST THU DEC 4 2008 LATEST UPDATE...SHORT TERM AND MARINE... .SYNOPSIS...(412 AM EST THU DEC 4 2008) COLDER AIR WILL CONTINUE MOVING IN OVER THE GREAT LAKES INTO THE DAY ON FRIDAY. THIS WILL ALLOW FOR LAKE EFFECT SNOW SHOWERS TO BE EXPECTED RIGHT ON THROUGH THE REMAINDER OF THE WEEK. SIGNIFICANT AMOUNTS OF LAKE EFFECT ARE NOT EXPECTED...HOWEVER SOME AREAS WILL SEE THE SNOWPACK GRADUALLY BUILD. AN AREA OF LOW PRESSURE WILL MOVE IN ACROSS THE REGION LATE FRIDAY NIGHT AND DURING THE DAY ON SATURDAY. THIS SYSTEM WILL BRING SOME SNOW TO MOST OF THE AREA...WITH LAKE ENHANCEMENT INCREASING AMOUNTS A BIT ALONG MOST OF THE LAKESHORE. && .SHORT TERM...(1040 AM EST THU DEC 4 2008) (REST OF TODAY THROUGH SATURDAY) I HAVE UPDATED THE FORECAST TO INCREASE THE AREA OF CONDITIONAL POP THROUGH THIS AFTERNOON. I ALSO INCREASED THE FORECAST SNOWFALL AMOUNTS FOR TODAY TO 1 TO 2 INCHES CENTERED ON US-131. THAT WAS BASED ON RADAR TRENDS AND THE IR AND WATER VAPOR IMAGES CONFERMING WHAT THE 12Z RUC SUGGESTS.... THAT IS CORE OF THE POLAR JET HAS PASSED EAST OF THE SOUTWEST MICHIGAN. WITH THE VAD WIND SUGGESTS THE INVERSION HEIGHT HAS INCREASED ABOUT 1000 FT FROM 5000 FT PRIOR TO 14Z TO ABOUT 6000 FT AT 15Z. TAMDAR SOUNDINGS SHOWS SIMILAR TRENDS. 850 MB TEMP CONTINUES TO FALL FROM AROUND -13C AT 12Z OVER LAKE MICHIGAN TO NEAR -15C BY 18Z. SFC OBS SHOW 1TO MILE VIS AT GRR LAN AZO RQB AT 15Z. ALSO THE RUC SHOWS THE DGZ HAS BECOME SATURATED AND WILL REMAIN SO THE REST OF THE DAY. THE BEST LIFT IS BETWEEN NOW AND 20Z. THE MEAN BOUNDARY LAYER WIND IS 270 DEGREES AROUND 25 KNOTS. THUS I BELIEVE WE WILL SEE SNOW ALL DAY OVER MOST OF THE CWA DOWN WIND OF LAKE MICHIGAN BETWEEN ROUTE 10 AND I-94. SOUTH OF I-94 WINDS ARE NOT OVER THE LAKE LONG ENOUGH TO REALLY DO MUCH IN TERMS OF SNOWFALL. NEXT SPEED MAX/SHORT WAVE TROUGH IS NOW DIVING SOUTHEAST OVER THE DAKOTAS AND MN. THIS SYSTEM WILL BE ENOUGH TO SEND THE POLAR JET SOUTH OF THE AREA TONIGHT. WITH THE APPROACH OF THE UPPER SYSTEMS....INVERSION HTS ARE EXPECTED TO INCREASE TO AROUND 8-9K FT. LOW LEVEL FLOW IS EXPECTED TO REMAIN MAINLY WNW THROUGH THE NIGHT. THE SYNOPTIC FORCING IN ADDITION TO THE FAVORABLE OVER-LAKE INSTABILITY WILL INCREASE THE INTENSITY OF THE SNOW SHOWERS. MODELS ARE INDICATING THAT A GOOD DEAL OF LOW LEVEL CONVERGENCE WILL DEVELOP LATE THIS EVENING AND LAST INTO THE OVERNIGHT HOURS. THE FAVORED AREAS WILL BE ROUGHLY SOUTH OF A LINE FROM GRAND HAVEN TO CHARLOTTE. THE LIMITED INVERSION HTS SHOULD KEEP THIS PICKUP IN LAKE EFFECT FROM GETTING TOO OUT OF HAND. WE DO NOT HAVE THE CONFIDENCE ANY LOCATION WILL SEE WARNING CRITERIA ACCUMS...HOWEVER WE DO BELIEVE THERE IS A GOOD CHANCE THAT AN ADVISORY MAY BE NEEDED. WE HAVE TRENDED AMOUNTS UP...AND ENOUGH TIME EXISTS THAT THE DAY SHIFT CAN TAKE ANOTHER LOOK AT POSSIBLE HEADLINES. INVERSION HTS WILL FALL A BIT AS THE SHORT WAVE MOVES AWAY FROM THE AREA ON FRI MORNING. WINDS ARE EXPECTED TO SHIFT FROM THE WNW TO MORE SW BY LATE FRI AFTERNOON. THIS WILL HELP TO KEEP ANY ONE AREA FROM SEEING MUCH SNOW. THE FOCUS OF BETTER SNOW ACCUMS WILL TRANSITION FROM THE SW CORNER OF THE CWFA TO THE NW CORNER. THE NEXT COUPLE OF SHORT WAVES WILL THEN DIVE SE TOWARD THE AREA LATE FRI NIGHT AND DURING THE DAY ON SAT. IT WILL BE THE SECOND SHORT WAVE THAT WILL BRING A CLIPPER TYPE SFC LOW ACROSS THE NRN PORTION OF THE STATE. THE SYSTEM ITSELF WILL BE POTENT...AND WOULD BRING A COUPLE OF INCHES OF SNOW BY ITSELF. H850 TEMPS DO NOT WARM ALL THAT MUCH AHEAD OF IT...LEAVING DELTA T/S AT LEAST IN THE MID TEENS ACROSS THE AREA. THE SW FLOW COMBINED WITH ALMOST A NON-EXISTENT INVERSION AND THE OVER-LAKE INSTABILITY WILL SET UP WHAT LOOKS TO BE A POTENTIALLY SIGNIFICANT LAKE ENHANCEMENT EVENT FOR THE NW PORTION OF THE CWFA. SOME DETAILS WILL NEED TO BE WORKED OUT...BUT THERE IS POTENTIAL FOR SOME WARNING CRITERIA SNOWS. THIS WILL BE LATE 4TH PERIOD/5TH PERIOD...SO WE WILL HOLD OFF ON ANY WATCH FOR NOW. && .LONG TERM...(412 AM EST THU DEC 4 2008) (SATURDAY NIGHT THROUGH WEDNESDAY) MAIN STORY IN THE LONG TERM WILL BE SNOW AND COLD. SURGES OF COLD AIR WILL PUSH INTO SOUTHWEST LOWER MICHIGAN DURING WEEKEND AND INTO THE MIDDLE OF NEXT WEEK. THE FIRST SURGE WILL RUSH IN SATURDAY NIGHT IN THE WAKE OF A CLIPPER SYSTEM MOVING OFF TO THE EAST. 850MB TEMPS ARE FORECAST TO PLUNGE INTO THE MIDDLE TEENS C BELOW ZERO. LAKE EFFECT WILL CONTINUE INTO SUNDAY...BEFORE RIDGING ENDS MUCH OF THE ACTIVITY INTO SUNDAY NIGHT. ANOTHER CLIPPER WILL MOVE THROUGH THE REGION MONDAY AND MONDAY NIGHT. THE ASSOCIATED COLD FRONT PUSHES THROUGH THE AREA TUESDAY MORNING. ARCTIC AIR POURS INTO THE GREAT LAKES REGION INTO MID WEEK...WITH 850MB TEMPS PLUNGING WELL INTO THE 20S BELOW ZERO C. SOME SYNOPTIC SCALE SNOW CAN BE EXPECTED MONDAY AND MONDAY NIGHT AS THE SYSTEM MOVES THROUGH...FOLLOWED BY GOOD CHANCES FOR LAKE EFFECT TUESDAY INTO WEDNESDAY. TRIED TO NUDGE DOWN TEMPS IN THE EXTENDED...GIVEN WHAT HAS BEEN A PERSISTENT SIGNAL BY THE GFS TO FORECAST A COLD PERIOD. TEMPERATURES FOR THE MIDDLE OF NEXT WEEK MAY VERY WELL BE DEEP WINTER TYPE NUMBERS WITH HIGHS IN THE TEENS AND LOWS DIPPING TOWARD ZERO. DID NOT GO THAT COLD YET...BUT HAVE BEGUN THE TREND IN THAT DIRECTION. && .MARINE...(1040 AM EST THU DEC 4 2008) I EXTENED THE SCA UNTIL 00Z SATURDAY SINCE THE WINDS AND WAVES ARE MORE THAN STRONG AND OR LARGE ENOUGH. WE MAY END UP WITH A GALE WARNING FOR LATE FRIDAY NIGHT ON LATER FORECASTS DUE THE STRONG SYSTEM COMING IN FROM THE NORTHWEST FOR SATURDAY. FREEZING SPRAY POTENTIAL WILL INCREASE AT THAT TIME WITH COLDER AIR MOVING IN. && .AVIATION...(655 AM EST THU DEC 4 2008) MAIN BATCH OF SNOW THAT MOVED THROUGH THE TAF SITES OVERNIGHT IS SLIDING EAST/DECREASING IN INTENSITY THIS MORNING. NOT EXPECTING MUCH IN THE WAY OF SNOW THROUGH THE DAY TODAY. LAKE EFFECT CLOUDS WILL CONTINUE TO BE IN PLACE ABOVE ALL THE TAF SITES HOWEVER. A GRADUAL LIFTING OF THE CEILING HEIGHTS IS EXPECTED...RISING FROM AROUND 2500FT THIS MORNING TO 3500FT THIS AFTERNOON. LAKE EFFECT SNOW IS EXPECTED TO INCREASE IN COVERAGE AND INTENSITY AS WE HEAD INTO THE EVENING HOURS. KMKG...KGRR AND KAZO SHOULD ALL SEE MVFR VISIBILITIES DEVELOP ONCE AGAIN AS SNOW SHOWERS MOVE THROUGH THOSE LOCATIONS. INLAND...TOWARD KLAN AND KJXN...IT SHOULD MAINLY BE FLURRIES. CEILINGS AREA WIDE SHOULD DIP BACK INTO THE MVFR CATEGORY ONCE AGAIN TONIGHT. && .HYDROLOGY...(412 AM EST THU DEC 4 2008) WITH TEMPERATURES EXPECTED TO GENERALLY BE BELOW FREEZING THROUGH THE NEXT WEEK...LITTLE TO NO RUNOFF CAN BE EXPECTED INTO AREA STREAMS AND RIVERS. IT DOES APPEAR THAT WE WILL BUILD A SNOWPACK WITH LAKE EFFECT SNOW SHOWERS EXPECTED MOST DAYS AND A FEW SYSTEMS MOVING THROUGH. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY IN EFFECT THROUGH 00Z SATURDAY. && $$ SYNOPSIS: NJJ SHORT TERM: NJJ / WDM LONG TERM: DUKE MARINE: NJJ / WDM AVIATION: DUKE HYDROLOGY: NJJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1155 AM CST FRI DEC 5 2008 .UPDATE...FOR 18Z AVIATION DISCUSSION BELOW && .DISCUSSION.../ISSUED 234 AM CST FRI DEC 5 2008/ MAIN FORECAST CONCERN THIS MORNING IS THE ALBERTA CLIPPER WHICH WILL MOVE THROUGH THE AREA TONIGHT AND ITS ASSOCIATED SNOWFALL AND GUSTY WINDS. THE GOING FORECAST HAD A GOOD HANDLE ON THE SITUATION... WITH THE MAIN ADJUSTMENT BEING A BIT QUICKER TIMING OF THINGS. LATEST WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSES SHOW THE DEPARTING UPPER TROUGH AND SHORTWAVE TO OUR EAST WITH A PROMINENT UPPER RIDGE OFF THE WEST COAST. A SHORTWAVE FEATURE IS EVIDENT ON THE DOWNSTREAM SIDE OF THE RIDGE MOVING INTO CENTRAL SASKATCHEWAN. THIS SHORTWAVE WILL DIVE SOUTHEAST OVER THE UPCOMING 24 HOURS... WORKING TO PUSH A SURFACE LOW ACROSS CENTRAL AND SOUTHERN CANADA WHILE DRIVING A COLD FRONT THROUGH OUR AREA. THE GFS AND NAM ARE REASONABLY SIMILAR ON THE OVERALL MASS FIELDS... BUT PREFERRED THE GFS MOISTURE FIELDS... PARTICULARLY ITS DEPICTION OF SATURATION ON THE ISENTROPIC SURFACES. ESSENTIALLY USED A BLEND OF THE GFS AND SREF GUIDANCE FOR THE FORECAST OVER THE NEXT FEW DAYS. ONCE TONIGHT/S SYSTEM MOVES BY... THE NEXT FEATURE OF INTEREST WILL BE ANOTHER SHORTWAVE MOVING IN ON NORTHWEST UPPER FLOW AND ITS ASSOCIATED ALBERTA CLIPPER SURFACE FEATURE... WHICH WILL SWING THROUGH THE AREA DURING THE LATE SUNDAY THROUGH MONDAY TIME FRAME. THE GOING FORECAST HAD A GOOD HANDLE ON THE EXPECTATIONS FOR THAT SYSTEM IN COMPARISON TO THE LATEST GUIDANCE... WITH ONCE AGAIN JUST SOME MINOR TWEAKS TO SPEED THE TIMING OF THINGS. SCT-BKN LOW CLOUDS WERE PRESENT OVER MUCH OF THE AREA THIS MORNING... LINGERING ON THE BACKSIDE OF THE LOW LEVEL THERMAL TROUGH. AS WARM ADVECTION CONTINUES TO INCREASE THESE LOW CLOUDS WILL MOVE EAST AND/OR SCOUR OUT. HOWEVER... THEY WILL BE QUICKLY REPLACED BY RAPIDLY INCREASING MID AND HIGH CLOUDS THIS MORNING DUE TO THE WARM ADVECTION AHEAD OF THE NEXT SHORTWAVE. THIS SYSTEM WILL BE A QUICK HITTER... IMPACTING THE CWFA FROM NORTHWEST TO SOUTHEAST... PRIMARILY BETWEEN 21Z AND 06Z. DEEP LAYER SATURATION COMES INTO BETTER ALIGNMENT AS THE SYSTEM MOVES THROUGH THE AREA... SO THE BETTER CHANCES FOR PCPN AND HIGHER SNOWFALL TOTALS WILL BE OVER THE NORTHEAST AND EASTERN PORTION OF THE AREA. THE BULK OF THE FORCING WILL BE DUE TO ISENTROPIC ASCENT OWING TO PRESSURE ADVECTION... ALONG AND AHEAD OF THE 925-500MB TROUGH AXIS. USED THE 285K ISENTROPIC SURFACE AS A PROXY FOR THE ARRIVAL OF PCPN AND THE LOCATION OF HIGHEST POPS AND GREATEST PCPN. MIXING RATIOS ON THIS SURFACE NEAR 700MB LOOK TO BE ON THE ORDER OF 1-2 G/KG... WHICH WOULD SUGGEST 2-4 INCHES FOR A 12-HOUR EVENT... BUT THE WINDOW OF OPPORTUNITY FOR THIS SYSTEM IS AROUND 4 OR 5 HOURS WHICH SUGGESTS MORE OF A 1-2 INCH EVENT FOR MOST LOCATIONS. QPF FROM THE GFS IS GENERALLY BETWEEN ONE AND TWO TENTHS OF AN INCH... WHICH WOULD ALSO FALL INTO THAT BALLPARK. A LOOK AT FORECAST SOUNDINGS AND LAPSE RATES... AS WELL AS EPV... DOES NOT SUGGEST A GREAT DEAL OF POTENTIAL ENHANCEMENT FROM STABILITY ARGUMENTS... WITH THE BETTER INSTABILITY LOCATED AOA 15K FEET... WHICH IS WELL ABOVE THE DENDRITIC GROWTH LAYER WHICH IS AROUND 10K FT. LAPSE RATES ARE ACTUALLY FAIRLY POOR IN THAT LAYER... WHICH DOES RESULT IN A DEEPER DENDRITIC GROWTH LAYER BUT ONE WHICH MAY NOT HAVE AUGMENTED UPWARD MOTION DUE TO INSTABILITY. SO... IN TERMS OF SNOWFALL RATIOS... WOULD BE TOUGH TO STRAY TO FAR FROM A CLIMATOLOGICAL OR EXPECTED VALUE FOR THE GIVEN AIRMASS... WHICH IS PROBABLY CLOSER TO 14 TO 1. SO... WILL GENERALLY PAINT 1 TO 2 INCHES OF SNOWFALL... WITH SOME MAXES BETWEEN 2 AND 3 OVER THE EASTERN PORTION OF THE FORECAST AREA WHERE THE WINDOW OF OPPORTUNITY WILL BE SLIGHTLY LONGER GIVEN A BETTER PERIOD OF DEEP LAYER SATURATION. SOUTHWEST WINDS WILL INCREASE THROUGH THE DAY TODAY AS THE GRADIENT STRENGTHENS... ALTHOUGH THE STRONGEST WINDS WILL BE WITH THE POST-FRONTAL COLD ADVECTION LATER TONIGHT AND SATURDAY MORNING WHEN NORTHWEST WINDS WILL GUST NEAR 30 MPH WORKING TO BLOW AROUND THE NEW FALLEN SNOW. AT THIS POINT SNOWFALL TOTALS AND EXPECTED WINDS DURING THE TIME OF FALLING SNOW LOOK LIKE THEY WILL NOT NECESSITATE AN ADVISORY... ALTHOUGH THIS WILL NEED TO BE MONITORED BY LATER SHIFTS. RIDGING AND ANTICYCLONIC FLOW LOOK TO BUILD IN QUICKLY BEHIND THE SYSTEM ON SATURDAY... WITH JUST SOME MORNING FLURRIES OVER THE EAST AND OTHERWISE DECREASING CLOUDS THROUGH THE DAY. HOWEVER... IT WON/T TAKE LONG FOR RETURN FLOW TO SET BACK UP... WITH WARM ADVECTION WORKING BACK IN BY SUNDAY AFTERNOON AND INCREASING MARKEDLY SUNDAY NIGHT AS THINGS SATURATE THROUGH THE COLUMN. WILL MAINTAIN THE IDEA OF INCREASING POPS FROM WEST TO EAST SUNDAY AFTERNOON AND SUNDAY NIGHT WITH HIGH CHANCE POPS. LATER FORECASTS WILL PROBABLY BE ABLE TO BUMP THE POPS UP FURTHER ONCE THE TIMING IS NAILED DOWN A BIT BETTER. THIS SHORTWAVE WILL SWING THROUGH ON MONDAY... DRIVING THE COLD FRONT THROUGH THE CWFA MONDAY AFTERNOON AND EVENING... WITH THE BOUNDARY LAYER FLOW QUICKLY BECOMING ANTICYCLONIC ONCE AGAIN WHICH SHOULD BRING A QUICK END TO PCPN MONDAY NIGHT. MADE NO ADJUSTMENTS TO THE GOING FORECAST BEYOND MONDAY. && .AVIATION.../18Z TAF ISSUANCE/ VIGOROUS SHORT WAVE RACING SOUTHEAST ACROSS NORTH DAKOTA THIS AFTERNOON...SHOULD AFFECT MUCH OF MN FA BY 00Z SAT. CIGS ALREADY BEGINNING TO LOWER WESTERN AREAS. PREVIOUS FCST LOOKED GOOD FOR TIMING...COMING IN THIS AFTERNOON KAXN-KRWF-KSTC AREAS AND MAINLY AFTER 00Z TO THE EAST. WILL SEE 1-3 INCH SNOW ACROSS THE AREA DURING THE LATE AFTERNOON/OVERNIGHT...WITH OCNL LIFR DURING THE HEAVIER SNOW PERIODS OVER EASTERN AREAS. WIND TO INCREASE WITH FROPA FIRST AT KAXN...LAST AT KEAU. SOME GUSTS TO 28-30KT PSBL WITH FROPA KAXN-KRWF AND WITH FRESH SNOW BLSN COULD BECOME A PROBLEM. SNOW SHOULD END IN THOSE AREAS WITH SOME MVFR VSBYS PSBL FOR A TIME. LOW CLOUDS TO REMAIN THROUGH 18Z ACROSS THE REGION...POSSIBLY BREAKING OUT OVER THE WEST INTO CENTRAL FA DURING THE AFTERNOON SAT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ DWE/TRH mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 602 AM CST FRI DEC 5 2008 .UPDATE...FOR 12Z AVIATION DISCUSSION BELOW && .DISCUSSION.../ISSUED 234 AM CST FRI DEC 5 2008/ MAIN FORECAST CONCERN THIS MORNING IS THE ALBERTA CLIPPER WHICH WILL MOVE THROUGH THE AREA TONIGHT AND ITS ASSOCIATED SNOWFALL AND GUSTY WINDS. THE GOING FORECAST HAD A GOOD HANDLE ON THE SITUATION... WITH THE MAIN ADJUSTMENT BEING A BIT QUICKER TIMING OF THINGS. LATEST WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSES SHOW THE DEPARTING UPPER TROUGH AND SHORTWAVE TO OUR EAST WITH A PROMINENT UPPER RIDGE OFF THE WEST COAST. A SHORTWAVE FEATURE IS EVIDENT ON THE DOWNSTREAM SIDE OF THE RIDGE MOVING INTO CENTRAL SASKATCHEWAN. THIS SHORTWAVE WILL DIVE SOUTHEAST OVER THE UPCOMING 24 HOURS... WORKING TO PUSH A SURFACE LOW ACROSS CENTRAL AND SOUTHERN CANADA WHILE DRIVING A COLD FRONT THROUGH OUR AREA. THE GFS AND NAM ARE REASONABLY SIMILAR ON THE OVERALL MASS FIELDS... BUT PREFERRED THE GFS MOISTURE FIELDS... PARTICULARLY ITS DEPICTION OF SATURATION ON THE ISENTROPIC SURFACES. ESSENTIALLY USED A BLEND OF THE GFS AND SREF GUIDANCE FOR THE FORECAST OVER THE NEXT FEW DAYS. ONCE TONIGHT/S SYSTEM MOVES BY... THE NEXT FEATURE OF INTEREST WILL BE ANOTHER SHORTWAVE MOVING IN ON NORTHWEST UPPER FLOW AND ITS ASSOCIATED ALBERTA CLIPPER SURFACE FEATURE... WHICH WILL SWING THROUGH THE AREA DURING THE LATE SUNDAY THROUGH MONDAY TIME FRAME. THE GOING FORECAST HAD A GOOD HANDLE ON THE EXPECTATIONS FOR THAT SYSTEM IN COMPARISON TO THE LATEST GUIDANCE... WITH ONCE AGAIN JUST SOME MINOR TWEAKS TO SPEED THE TIMING OF THINGS. SCT-BKN LOW CLOUDS WERE PRESENT OVER MUCH OF THE AREA THIS MORNING... LINGERING ON THE BACKSIDE OF THE LOW LEVEL THERMAL TROUGH. AS WARM ADVECTION CONTINUES TO INCREASE THESE LOW CLOUDS WILL MOVE EAST AND/OR SCOUR OUT. HOWEVER... THEY WILL BE QUICKLY REPLACED BY RAPIDLY INCREASING MID AND HIGH CLOUDS THIS MORNING DUE TO THE WARM ADVECTION AHEAD OF THE NEXT SHORTWAVE. THIS SYSTEM WILL BE A QUICK HITTER... IMPACTING THE CWFA FROM NORTHWEST TO SOUTHEAST... PRIMARILY BETWEEN 21Z AND 06Z. DEEP LAYER SATURATION COMES INTO BETTER ALIGNMENT AS THE SYSTEM MOVES THROUGH THE AREA... SO THE BETTER CHANCES FOR PCPN AND HIGHER SNOWFALL TOTALS WILL BE OVER THE NORTHEAST AND EASTERN PORTION OF THE AREA. THE BULK OF THE FORCING WILL BE DUE TO ISENTROPIC ASCENT OWING TO PRESSURE ADVECTION... ALONG AND AHEAD OF THE 925-500MB TROUGH AXIS. USED THE 285K ISENTROPIC SURFACE AS A PROXY FOR THE ARRIVAL OF PCPN AND THE LOCATION OF HIGHEST POPS AND GREATEST PCPN. MIXING RATIOS ON THIS SURFACE NEAR 700MB LOOK TO BE ON THE ORDER OF 1-2 G/KG... WHICH WOULD SUGGEST 2-4 INCHES FOR A 12-HOUR EVENT... BUT THE WINDOW OF OPPORTUNITY FOR THIS SYSTEM IS AROUND 4 OR 5 HOURS WHICH SUGGESTS MORE OF A 1-2 INCH EVENT FOR MOST LOCATIONS. QPF FROM THE GFS IS GENERALLY BETWEEN ONE AND TWO TENTHS OF AN INCH... WHICH WOULD ALSO FALL INTO THAT BALLPARK. A LOOK AT FORECAST SOUNDINGS AND LAPSE RATES... AS WELL AS EPV... DOES NOT SUGGEST A GREAT DEAL OF POTENTIAL ENHANCEMENT FROM STABILITY ARGUMENTS... WITH THE BETTER INSTABILITY LOCATED AOA 15K FEET... WHICH IS WELL ABOVE THE DENDRITIC GROWTH LAYER WHICH IS AROUND 10K FT. LAPSE RATES ARE ACTUALLY FAIRLY POOR IN THAT LAYER... WHICH DOES RESULT IN A DEEPER DENDRITIC GROWTH LAYER BUT ONE WHICH MAY NOT HAVE AUGMENTED UPWARD MOTION DUE TO INSTABILITY. SO... IN TERMS OF SNOWFALL RATIOS... WOULD BE TOUGH TO STRAY TO FAR FROM A CLIMATOLOGICAL OR EXPECTED VALUE FOR THE GIVEN AIRMASS... WHICH IS PROBABLY CLOSER TO 14 TO 1. SO... WILL GENERALLY PAINT 1 TO 2 INCHES OF SNOWFALL... WITH SOME MAXES BETWEEN 2 AND 3 OVER THE EASTERN PORTION OF THE FORECAST AREA WHERE THE WINDOW OF OPPORTUNITY WILL BE SLIGHTLY LONGER GIVEN A BETTER PERIOD OF DEEP LAYER SATURATION. SOUTHWEST WINDS WILL INCREASE THROUGH THE DAY TODAY AS THE GRADIENT STRENGTHENS... ALTHOUGH THE STRONGEST WINDS WILL BE WITH THE POST-FRONTAL COLD ADVECTION LATER TONIGHT AND SATURDAY MORNING WHEN NORTHWEST WINDS WILL GUST NEAR 30 MPH WORKING TO BLOW AROUND THE NEW FALLEN SNOW. AT THIS POINT SNOWFALL TOTALS AND EXPECTED WINDS DURING THE TIME OF FALLING SNOW LOOK LIKE THEY WILL NOT NECESSITATE AN ADVISORY... ALTHOUGH THIS WILL NEED TO BE MONITORED BY LATER SHIFTS. RIDGING AND ANTICYCLONIC FLOW LOOK TO BUILD IN QUICKLY BEHIND THE SYSTEM ON SATURDAY... WITH JUST SOME MORNING FLURRIES OVER THE EAST AND OTHERWISE DECREASING CLOUDS THROUGH THE DAY. HOWEVER... IT WON/T TAKE LONG FOR RETURN FLOW TO SET BACK UP... WITH WARM ADVECTION WORKING BACK IN BY SUNDAY AFTERNOON AND INCREASING MARKEDLY SUNDAY NIGHT AS THINGS SATURATE THROUGH THE COLUMN. WILL MAINTAIN THE IDEA OF INCREASING POPS FROM WEST TO EAST SUNDAY AFTERNOON AND SUNDAY NIGHT WITH HIGH CHANCE POPS. LATER FORECASTS WILL PROBABLY BE ABLE TO BUMP THE POPS UP FURTHER ONCE THE TIMING IS NAILED DOWN A BIT BETTER. THIS SHORTWAVE WILL SWING THROUGH ON MONDAY... DRIVING THE COLD FRONT THROUGH THE CWFA MONDAY AFTERNOON AND EVENING... WITH THE BOUNDARY LAYER FLOW QUICKLY BECOMING ANTICYCLONIC ONCE AGAIN WHICH SHOULD BRING A QUICK END TO PCPN MONDAY NIGHT. MADE NO ADJUSTMENTS TO THE GOING FORECAST BEYOND MONDAY. && .AVIATION.../12Z TAF ISSUANCE/ LOW-END VFR CIGS WILL SHIFT EAST OF THE TAF SITES THIS MORNING...BUT BE REPLACED BY MID/HIGH CLOUDS SHORTLY AFTERWARD...AS THE NEXT CLIPPER SYSTEM DRAWS NEAR. HAVE SPED UP THE ARRIVAL OF THE ASSOCIATED SNOWFALL WITH THIS SYSTEM...CONSISTENT WITH MODEL TRENDS. EXPECT SNOW TO REACH KAXN/KSTC AROUND 20Z...KRWF/KSMP AROUND 22Z...AND KRNH/KEAU BY 00Z. EXPECT IFR VSBYS WITH THE SNOWFALL...WITH OCCASIONAL DIPS TO THE LIFR CATEGORY THIS EVENING. EXPECT MAINLY MVFR CIGS WITH THE SNOWFALL. GUSTY NORTHWEST WINDS BEHIND THE FROPA WILL LIKELY RESULT IN SOME BLOWING SNOW TONIGHT AS WELL. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ LS/TRH mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 234 AM CST FRI DEC 5 2008 .DISCUSSION... MAIN FORECAST CONCERN THIS MORNING IS THE ALBERTA CLIPPER WHICH WILL MOVE THROUGH THE AREA TONIGHT AND ITS ASSOCIATED SNOWFALL AND GUSTY WINDS. THE GOING FORECAST HAD A GOOD HANDLE ON THE SITUATION... WITH THE MAIN ADJUSTMENT BEING A BIT QUICKER TIMING OF THINGS. LATEST WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSES SHOW THE DEPARTING UPPER TROUGH AND SHORTWAVE TO OUR EAST WITH A PROMINENT UPPER RIDGE OFF THE WEST COAST. A SHORTWAVE FEATURE IS EVIDENT ON THE DOWNSTREAM SIDE OF THE RIDGE MOVING INTO CENTRAL SASKATCHEWAN. THIS SHORTWAVE WILL DIVE SOUTHEAST OVER THE UPCOMING 24 HOURS... WORKING TO PUSH A SURFACE LOW ACROSS CENTRAL AND SOUTHERN CANADA WHILE DRIVING A COLD FRONT THROUGH OUR AREA. THE GFS AND NAM ARE REASONABLY SIMILAR ON THE OVERALL MASS FIELDS... BUT PREFERRED THE GFS MOISTURE FIELDS... PARTICULARLY ITS DEPICTION OF SATURATION ON THE ISENTROPIC SURFACES. ESSENTIALLY USED A BLEND OF THE GFS AND SREF GUIDANCE FOR THE FORECAST OVER THE NEXT FEW DAYS. ONCE TONIGHT/S SYSTEM MOVES BY... THE NEXT FEATURE OF INTEREST WILL BE ANOTHER SHORTWAVE MOVING IN ON NORTHWEST UPPER FLOW AND ITS ASSOCIATED ALBERTA CLIPPER SURFACE FEATURE... WHICH WILL SWING THROUGH THE AREA DURING THE LATE SUNDAY THROUGH MONDAY TIME FRAME. THE GOING FORECAST HAD A GOOD HANDLE ON THE EXPECTATIONS FOR THAT SYSTEM IN COMPARISON TO THE LATEST GUIDANCE... WITH ONCE AGAIN JUST SOME MINOR TWEAKS TO SPEED THE TIMING OF THINGS. SCT-BKN LOW CLOUDS WERE PRESENT OVER MUCH OF THE AREA THIS MORNING... LINGERING ON THE BACKSIDE OF THE LOW LEVEL THERMAL TROUGH. AS WARM ADVECTION CONTINUES TO INCREASE THESE LOW CLOUDS WILL MOVE EAST AND/OR SCOUR OUT. HOWEVER... THEY WILL BE QUICKLY REPLACED BY RAPIDLY INCREASING MID AND HIGH CLOUDS THIS MORNING DUE TO THE WARM ADVECTION AHEAD OF THE NEXT SHORTWAVE. THIS SYSTEM WILL BE A QUICK HITTER... IMPACTING THE CWFA FROM NORTHWEST TO SOUTHEAST... PRIMARILY BETWEEN 21Z AND 06Z. DEEP LAYER SATURATION COMES INTO BETTER ALIGNMENT AS THE SYSTEM MOVES THROUGH THE AREA... SO THE BETTER CHANCES FOR PCPN AND HIGHER SNOWFALL TOTALS WILL BE OVER THE NORTHEAST AND EASTERN PORTION OF THE AREA. THE BULK OF THE FORCING WILL BE DUE TO ISENTROPIC ASCENT OWING TO PRESSURE ADVECTION... ALONG AND AHEAD OF THE 925-500MB TROUGH AXIS. USED THE 285K ISENTROPIC SURFACE AS A PROXY FOR THE ARRIVAL OF PCPN AND THE LOCATION OF HIGHEST POPS AND GREATEST PCPN. MIXING RATIOS ON THIS SURFACE NEAR 700MB LOOK TO BE ON THE ORDER OF 1-2 G/KG... WHICH WOULD SUGGEST 2-4 INCHES FOR A 12-HOUR EVENT... BUT THE WINDOW OF OPPORTUNITY FOR THIS SYSTEM IS AROUND 4 OR 5 HOURS WHICH SUGGESTS MORE OF A 1-2 INCH EVENT FOR MOST LOCATIONS. QPF FROM THE GFS IS GENERALLY BETWEEN ONE AND TWO TENTHS OF AN INCH... WHICH WOULD ALSO FALL INTO THAT BALLPARK. A LOOK AT FORECAST SOUNDINGS AND LAPSE RATES... AS WELL AS EPV... DOES NOT SUGGEST A GREAT DEAL OF POTENTIAL ENHANCEMENT FROM STABILITY ARGUMENTS... WITH THE BETTER INSTABILITY LOCATED AOA 15K FEET... WHICH IS WELL ABOVE THE DENDRITIC GROWTH LAYER WHICH IS AROUND 10K FT. LAPSE RATES ARE ACTUALLY FAIRLY POOR IN THAT LAYER... WHICH DOES RESULT IN A DEEPER DENDRITIC GROWTH LAYER BUT ONE WHICH MAY NOT HAVE AUGMENTED UPWARD MOTION DUE TO INSTABILITY. SO... IN TERMS OF SNOWFALL RATIOS... WOULD BE TOUGH TO STRAY TO FAR FROM A CLIMATOLOGICAL OR EXPECTED VALUE FOR THE GIVEN AIRMASS... WHICH IS PROBABLY CLOSER TO 14 TO 1. SO... WILL GENERALLY PAINT 1 TO 2 INCHES OF SNOWFALL... WITH SOME MAXES BETWEEN 2 AND 3 OVER THE EASTERN PORTION OF THE FORECAST AREA WHERE THE WINDOW OF OPPORTUNITY WILL BE SLIGHTLY LONGER GIVEN A BETTER PERIOD OF DEEP LAYER SATURATION. SOUTHWEST WINDS WILL INCREASE THROUGH THE DAY TODAY AS THE GRADIENT STRENGTHENS... ALTHOUGH THE STRONGEST WINDS WILL BE WITH THE POST-FRONTAL COLD ADVECTION LATER TONIGHT AND SATURDAY MORNING WHEN NORTHWEST WINDS WILL GUST NEAR 30 MPH WORKING TO BLOW AROUND THE NEW FALLEN SNOW. AT THIS POINT SNOWFALL TOTALS AND EXPECTED WINDS DURING THE TIME OF FALLING SNOW LOOK LIKE THEY WILL NOT NECESSITATE AN ADVISORY... ALTHOUGH THIS WILL NEED TO BE MONITORED BY LATER SHIFTS. RIDGING AND ANTICYCLONIC FLOW LOOK TO BUILD IN QUICKLY BEHIND THE SYSTEM ON SATURDAY... WITH JUST SOME MORNING FLURRIES OVER THE EAST AND OTHERWISE DECREASING CLOUDS THROUGH THE DAY. HOWEVER... IT WON/T TAKE LONG FOR RETURN FLOW TO SET BACK UP... WITH WARM ADVECTION WORKING BACK IN BY SUNDAY AFTERNOON AND INCREASING MARKEDLY SUNDAY NIGHT AS THINGS SATURATE THROUGH THE COLUMN. WILL MAINTAIN THE IDEA OF INCREASING POPS FROM WEST TO EAST SUNDAY AFTERNOON AND SUNDAY NIGHT WITH HIGH CHANCE POPS. LATER FORECASTS WILL PROBABLY BE ABLE TO BUMP THE POPS UP FURTHER ONCE THE TIMING IS NAILED DOWN A BIT BETTER. THIS SHORTWAVE WILL SWING THROUGH ON MONDAY... DRIVING THE COLD FRONT THROUGH THE CWFA MONDAY AFTERNOON AND EVENING... WITH THE BOUNDARY LAYER FLOW QUICKLY BECOMING ANTICYCLONIC ONCE AGAIN WHICH SHOULD BRING A QUICK END TO PCPN MONDAY NIGHT. MADE NO ADJUSTMENTS TO THE GOING FORECAST BEYOND MONDAY. && .AVIATION.../06Z TAF ISSUANCE/ ...ACCUMULATING SNOW/IFR CONDS EXPECTED LATE AFTERNOON/EARLY EVENING FRIDAY... FAIRLY QUIET WEATHER IN THE NEAR TERM WITH HIGH PRESSURE SETTLING TO THE SOUTHWEST OF THE REGION. 2500 TO 4000FT CLOUDS CONTINUE TO FILL THE SKIES TONIGHT. LARGE BREAK IN THE CLOUDS NOW PASSING OVER CENTRAL MN AND WESTERN WI BUT SATELLITE IMAGERY SHOWS MORE 3000 TO 4000 FT CLOUDS UPSTREAM HEADED THIS WAY. OPTED FOR MOSTLY BROKEN SKIES INTO THE MORNING HOURS. WEST-NORTHWEST WINDS WILL BECOME SOUTHWESTERLY LATE TONIGHT AND THROUGH THE MORNING AHEAD OF AN ADVANCING ALBERTA CLIPPER. EXCEPT FOR A FEW BOUTS OF 2500 TO 3000 FT CIGS TONIGHT VFR CONDITIONS WILL PREVAIL INTO THE EARLY/MID AFTERNOON AT ALL SITES. MID CLOUDS WILL RAPIDLY INCREASE FROM MORNING ONWARD AHEAD OF THE CLIPPER. THIS CLIPPER LOOKS TO BE BETTER ORGANIZED/STRONGER THAN RECENT SYSTEMS THUS WIDESPREAD SNOWFALL LOOKS MORE LIKELY. EXPECT A 3 TO 5 HOUR WINDOW OF LOW CONDITIONS UNDER INTENSE SNOWFALL...ESPECIALLY AS THE SYSTEM ENTERS EAST CENTRAL MN AND WEST CENTRAL WI FRIDAY EVENING...WITH LARGER WINDOW OF MVFR CONDS WITH LIGHTER SNOW. CEILINGS WILL QUICKLY FALL AS THE SYSTEM APPROACHES WITH SNOW STARTING SOON AFTER. SNOW SHOULD BEGIN AT KAXN BY LATE AFTERNOON AND MOVE QUICKLY SOUTHEAST STARTING AT KSTC AND KRWF AFTER 23Z OR SO. KMSP AND KRNH WILL QUICKLY SEE DETERIORATING CONDITIONS AROUND/JUST AFTER 00-01Z WITH KEAU STARTING AROUND 02-03Z. WILL NEED TO WATCH THIS TIMING AS IT MAY NEED TO BE ADJUSTED AN HOUR OR SO IN EITHER DIRECTION. SNOW SHOULD ACCUMULATE QUICKLY WITH AN INCH OR 2 AT KAXN AND KRWF WITH 2 TO 3 AT KSTC/KRNH/KEAU. VISIBILITY IS EXPECTED TO DROP TO 1 TO 2 SM AT KAXN/KSTC/KRWF AND TO LESS THAN 1 SM AT KMSP/KRNH/KEAU. CIGS OF 500 TO 800 FEET ARE ALSO POSSIBLE AT THESE THREE SITES UNDER THE HEAVIEST SNOWFALL WITH CIGS PREDOMINATELY BETWEEN 1000 AND 2000 FT OUTSIDE OF THE HEAVIEST SNOW. WINDS WILL QUICKLY TURN WESTERLY TO NORTHWESTERLY AS THE SNOW WINDS DOWN AND BECOME GUSTY IN THE WEST CREATING SOME BLOWING SNOW CONCERNS. HAVE INDICATED MVFR VIS IN THE BLSN AT KAXN/KRWF/KSTC BUT WILL HAVE TO CONTINUE TO WATCH THIS THREAT. LIGHT SNOW/FLURRIES ALSO EXPECTED THROUGH MUCH OF THE NIGHT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ TRH/MDB mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 318 PM CST THU DEC 4 2008 .DISCUSSION...MAIN FORECAST CHALLENGES ARE ENDING LES EVENT AND CLIPPER SYSTEM FOR FRIDAY NIGHT. AFTERNOON WATER VAPOR LOOP SHOWS DEEP COLD CORE TROUGH CONTINUING TO SINK SOUTHEAST OVER THE UPPER MIDWEST/WESTERN GREAT LAKES. SURFACE WINDS HAVE BACKED WESTERLY...AND WILL CONTINUE TO DO SO THIS EVENING AS THE UPPER TROUGH PUSHES EASTWARD. AS A RESULT...LAKE EFFECT SNOW BANDS SHOULD CONTINUE TO MIGRATE EASTWARD...OUT OF THE FA...DESPITE CONTINUED COLD AIRMASS IN PLACE OVER WESTERN LAKE SUPERIOR /H85 TEMPS AROUND -20C ATTM/. LET WARNING EXPIRE AS SCHEDULED ACCORDINGLY. OTHERWISE...CONVECTIVE CLOUD STREETS ALONG WITH SCT FLURRIES/SHSN WILL DIMINISH THIS EVENING AND OVERNIGHT...SETTING UP A COLD NIGHT FOR THE NORTHLAND. WINDS OF 5 TO 10 MPH ALONG WITH SFC LOWS REACHING THE SINGLE DIGITS ABOVE AND BELOW ZERO WILL RESULT IN WIND CHILLS IN THE 10 TO 20 BELOW ZERO RANGE FOR LATE TONIGHT AND FRIDAY MORNING. SHOULD SEE A FAIRLY GOOD RECOVERY OF TEMPS FRIDAY AHEAD OF NEXT APPROACHING ALBERTA CLIPPER SYSTEM. FORECAST ATTENTION THEN TURNS POSITIVELY TILTED TROUGH DIVING SOUTHEAST FRIDAY EVENING THROUGH THE OVERNIGHT ACROSS THE DLH FA. THIS SYSTEM LOOKS TO BRING GENERALLY 1 TO 3 INCHES TO THE NORTHLAND...WITH THE HIGHEST AMOUNTS INTO NORTHWEST WISCONSIN WHERE STRONGEST 2-D FGEN OCCURS LATE FRIDAY NIGHT PER NAM. GUSTY WINDS ALONG WITH THIS EVENT BEING THE FIRST WIDESPREAD ACCUMULATING SNOW WILL MAKE FOR SOME TRAVEL PROBLEMS INTO SATURDAY MORNING. A LES EVENT LOOKS LIKELY ONCE AGAIN FOR THE SOUTH SHORE WITH A GUSTY NORTHWEST WINDS...AND H85 TEMPS DROPPING TO NEAR -20C SATURDAY THROUGH SATURDAY NIGHT. .EXTENDED...SUNDAY THROUGH THURSDAY EXTENDED PERIOD WILL BEGIN WITH BRIEF RIDGING ON SUNDAY...WITH LAKE EFFECT SNOWS DIMINISHING OVER NW WISCONSIN...AND DRY WEATHER ELSEWHERE. WAA AND ISENTROPIC LIFT WILL BRING INCREASING CLOUDS AND SNOW CHANCES BY SUNDAY NIGHT INTO MONDAY...GENERALLY FROM WEST TO EAST. WHILE DEEP MOISTURE WILL BE LIMITED...SOME LIGHT TO MODERATE SNOW ACCUMULATIONS CERTAINLY APPEAR POSSIBLE. WEAK HIGH PRESSURE WILL THEN RETURN LATE MONDAY INTO EARLY TUESDAY...EXCEPT FOR SOME LINGERING LIGHT SNOW OVER OUR EASTERN ZONES. ANOTHER CLIPPER SYSTEM WILL BRING A ROUND OF LIGHT SNOW TO MUCH OF THE REGION ON WEDNESDAY...BEFORE A MORE POTENT SYSTEM APPROACHES FROM THE SOUTHWEST LATE WEDNESDAY INTO THURSDAY. MODELS ARE IN A BIT OF DISAGREEMENT...BUT GENERALLY PREFER THE GFS AND GFS ENSEMBLES...WHICH DO NOT SUPPORT SIGNIFICANT PHASING OF THE NORTHERN AND SOUTHERN BRANCHES OF THE JET OVER THE PLAINS. THIS WOULD EFFECTIVELY KEEP THE LOW WEAKER AND A TAD FURTHER SOUTH. OTHERWISE...COLD AND BELOW NORMAL TEMPERATURES WILL PREVAIL THROUGH THE PERIOD WITH A DEEP H5 TROUGH CENTERED NEAR HUDSON BAY. THE COLDEST TEMPERATURES ARE LIKELY WEDNESDAY INTO THURSDAY...WITH H85 TEMPS OF -20C TO -24C. HOWEVER....THE GFS SUGGESTS TEMPERATURES WILL BEGIN TO WARM SLIGHTLY BY LATE THURSDAY AND BEYOND AS THE THE TROUGH SLOWLY PUSHES OFF TO THE NORTH AND EAST. WE BELIEVE THIS MAY BE A BIT FAST...ESPECIALLY WHEN CONSIDERING OTHER MODEL GUIDANCE...AND ONLY WARMED TEMPERATURES SLIGHTLY. && .AVIATION...LOW VFR AND MVFR CEILINGS WILL PREVAIL THROUGH 18Z FRIDAY. SCATTERED SNOW SHOWERS WILL ALSO PERSIST THROUGH 00Z THIS EVENING...AND MAY ALSO BRING VSBYS AS LOW AS 2SM. THE RUC13 AND NAM12 SUGGEST A TEMPORARY RISE IN CEILING HEIGHTS AND MAINLY SCATTERED CLOUDS FOR SOUTHERN AREAS INCLUDING KBRD DURING THE EVENING HOURS...FROM 00Z TO 06Z...BEFORE MVFR AGAIN BECOMES MORE PREVALENT AFTER 06Z. WARM AIR ADVECTION WILL SPREAD MID LEVEL CLOUDS INTO THE REGION ON FRIDAY MORNING...AHEAD OF AN APPROACHING SHORTWAVE...BUT CEILINGS WILL REMAIN MOSTLY LOW VFR THROUGH 18Z...BEFORE DETERIORATING TO MVFR FROM NORTHWEST TO SOUTHEAST IN LOW CLOUDS AND LIGHT SNOW FRIDAY AFTERNOON. && POINT TEMPS/POPS... DLH 0 18 11 16 / 20 20 80 30 INL -4 15 1 8 / 20 40 80 20 BRD 0 21 14 17 / 10 20 80 20 HYR -2 19 13 20 / 20 10 80 40 ASX 5 18 11 19 / 50 20 80 50 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 4 PM CST FRIDAY FOR LSZ121-LSZ146- LSZ147-LSZ148. $$ LILES/BETTWY mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 508 AM CST THU DEC 4 2008 .AVIATION.../12Z TAF ISSUANCE/ LATEST RADAR IMAGERY SHOWS PATCH OF LIGHT SNOW MOVING THROUGH THE CENTRAL PORTION OF THE AREA AT THE CURRENT TIME... IN ASSOCIATION WITH AN UPPER LEVEL SHORTWAVE AND WEAK SURFACE TROUGH. THIS FEATURE WILL SWING EAST THIS MORNING... AND THE WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSES SHOW SOME DECENT SHORTWAVE RIDGING MOVING SOUTH THROUGH SASKATCHEWAN AND MANITOBA WHICH WILL WORK SOUTHEAST THROUGH THE DAY AND INTO THIS EVENING. CLOUD COVER ACROSS THE AREA AT THIS TIME IS NOT PARTICULARLY HOMOGENEOUS... WITH SOME THICKER CLOUDS ASSOCIATED WITH THE AFOREMENTIONED FEATURES AND PCPN. IN THEIR WAKE... AREAS OF BKN MAINLY VFR AND MARGINAL MVFR CEILINGS COULD BE FOUND. BOUNDARY LAYER MOISTURE... AS SHOWN BY THE NAM... GFS... AND RUC... ARE SUFFICIENT FOR SOME STRATOCU THROUGH THE DAY... BUT CYCLONIC FLOW IS MINIMAL LIKELY KEEPING THINGS IN CHECK. HOWEVER... WITH THE THERMAL TROUGH IN THE VICINITY TODAY AND AT LEAST NEUTRAL IF NOT SLIGHTLY CYCLONIC FLOW... WE SHOULD SEE MORE IN THE WAY OF STRATOCU THAN YESTERDAY... BUT FORECAST PROFILES SUGGEST IT SHOULD GENERALLY STAY AOA 3K FT EXCEPT FOR PERHAPS IN SOME OF THE SCATTERED SNOW SHOWERS WHICH COULD DEVELOP GIVEN THE GOOD LOW LEVEL LAPSE RATES WHICH WILL LINGER THROUGH THE DAY. TONIGHT... THE GENERAL TREND SHOULD BE FOR IMPROVEMENT IN CONDITIONS AS WINDS BACK AND WARM ADVECTION STARTS TO WORK ITS WAY DOWN FROM THE MID LEVELS AND DEWPOINT DEPRESSIONS INCREASE. HOWEVER... THERE COULD BE SOME LOWERING IN CEILINGS AS THE SUBSIDENCE INVERSION LOWERS BEFORE THE CLOUDS ARE SCOURED OUT. WILL INCLUDE SOME HINT OF THIS TREND... BUT OTHERWISE ANTICIPATE A SCATTERING OUT OF ANY BKN LOWER CLOUDS FROM WEST TO EAST THROUGH THE NIGHT. && .PREV DISCUSSION... /ISSUED 426 AM CST THU DEC 4 2008/ AN AREA OF LIGHT SNOW CONTINUES TO TRAIPSE ACROSS THE FORECAST AREA EARLY THIS MORNING...INDUCED BY FAINT SHORTWAVE ENERGY IN THE BASE OF THE TROUGH CENTERED OVER HUDSON BAY. THE ASSOCIATED AREA OF 850-500MB Q VECTOR CONVERGENCE SHIFTS EAST OF THE CWA THIS MORNING...WITH MEASURABLE SNOWFALL EXPECTED TO END AROUND DAYBREAK. HOWEVER...SCATTERED FLURRIES WILL BE POSSIBLE FOR A GOOD PORTION OF THE DAY UNDER THE INFLUENCE OF THE DEPARTING UPPER TROUGH. COLD AIR ADVECTION AND AN 850MB TEMPERATURE DECLINE TO AROUND -20C WILL CONTRIBUTE TO MAX TEMPS AROUND 10 TO 15 DEGREES BELOW CLIMATOLOGICAL NORMALS...AS READINGS TOP OUT IN THE MID/UPPER TEENS AND LOW 20S. AFTER TODAY...ATTENTION SHIFTS TO A CLIPPER SYSTEM PROGGED TO DIP ACROSS THE NORTH CENTRAL CONUS ON FRIDAY. THERE WAS GOOD AGREEMENT BETWEEN THE LATEST RUNS OF THE GFS/NAM/ECMWF IN BRINGING MEASURABLE SNOWFALL TO THE CWA BETWEEN 00Z AND 12Z SATURDAY. SNOWFALL AMOUNTS BETWEEN ONE AND TWO INCHES APPEAR LIKELY...ESPECIALLY ACROSS NORTH/EAST CENTRAL MN AND WEST CENTRAL WI...WHERE SNOW GROWTH SHOULD BE DECENT PER PROGS OF 4-5 -UBAR/S OF OMEGA AT THE -15C TEMPERATURE LEVEL. CHILLY TEMPERATURES PREVAIL OVER THE WEEKEND...WITH A LOW LEVEL HIGH PRESSURE RIDGE IN CONTROL. THE NEXT SHORTWAVE TROUGH IN THE PARADE IS FORECAST TO ARRIVE LATE SUNDAY AND MONDAY. ALTHOUGH THERE ARE STILL NOTABLE DIFFERENCE IN THE MODEL SOLUTIONS WITH RESPECT TO TIMING/PLACEMENT ASPECTS OF THIS FEATURE...AGREEMENT IS DECENT ENOUGH TO WARRANT HIGH CHANCE POPS BETWEEN 00Z MONDAY AND 00Z TUESDAY. HIGH PRESSURE WILL MAKE A FLEETING APPEARANCE LATE MONDAY INTO TUESDAY...WITH YET ANOTHER WEAK SYSTEM EXPECTED BY MIDWEEK. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ TRH/LS mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTH PLATTE NE 1019 PM CST FRI DEC 5 2008 .UPDATE... CLOUD COVER AND MIXED BOUNDARY LAYER WILL KEEP LOW TEMPERATURES UP TONIGHT. VORT MAX HAS MOVED THROUGH WITH MID LEVEL FORCING AND MIXED LIGHT PRECIPITATION ENDING. HAVE REMOVED PRECIPITATION FOR THE REMAINDER OF THE NIGHT. && .PREV DISCUSSION... /ISSUED 256 PM CST FRI DEC 5 2008/ DISCUSSION... MID LEVEL COLD FRONT WILL DRAPE THROUGH NCNTL NEB THIS EVENING ACTING AS A FOCUS FOR VERY LIGHT SNOW...POSSIBLY MIXED WITH RAIN BEFORE NIGHTFALL. THIS FRONT WILL DRAPE ACROSS THE NERN PORTION OF THE FCST AREA SATURDAY PRODUCING WIDESPREAD CLOUDINESS AND PERHAPS SOME LIGHT SNOW. THE FRONT AND WARM AIR ADVECTION BEGIN OPERATING SATURDAY NIGHT AS BOTH THE NAM AND GFS INDICATE LIGHT SNOW DEVELOPING SATURDAY NIGHT FOR A TIME. LESS THAN AN INCH OF SNOW IS EXPECTED. FOR SUNDAY...THE WARM AIR WINS OUT AS THE WARM FRONT PUSHES EAST. ALL AREAS SHOULD CLEAR OUT AT THE LOWER LEVELS BUT PERSISTENT MID AND UPPER LEVEL MOISTURE WILL REMAIN ACROSS THE CENTRAL PLAINS. THE WARM AIR SHOULD BE SUFFICIENT FOR TEMPERATURES TO RISE INTO THE 40S ACROSS MOST OF THE AREA WITH 30S IN THE FAR ERN PTN OF THE FCST AREA. MONDAY...A COLD FRONT WILL DROP THROUGH THE FCST AREA. THE ECMWF IS VERY ACTIVE SUGGESTING A FAIRLY WIDESPREAD RAIN-SNOW EVENT MONDAY AND MONDAY NIGHT. THE GFS...NAM12...NOGAPS AND GEM INDICATE THE BEST FORCING WILL BE ACROSS WRN KS AND ERN COLO. THE ECMWF HAS NOT BEEN FULLY DISCOUNTED SO 20 TO 30 POPS BLANKET THE FCST AREA MONDAY AND MONDAY NIGHT. LATER FCSTS CAN RAISE OF LOWER THE POP AS THE MODELS COME INTO BETTER AGREEMENT. THE PROBLEM IS SOME FISHY UPPER LEVEL ENERGY ACROSS THE ERN PAC WHICH SOME MODELS PHASE FARTHER SOUTH VS THE ECMWF WHICH OPERATES FARTHER NORTH. IF THE ECMWF IS WRONG THEN ONLY SWRN NEB WILL GET PCPN FROM THIS SYSTEM. TUESDAY AND WEDNESDAY...TEMPERATURES MODERATE TO SEASONABLE LEVELS AS A WARM FRONT DEVELOPS AND PUSHES EAST ACROSS NEB. THE FCST IS DRY DURING THIS TIME. THURSDAY AND FRIDAY...A WEAK COLD FRONT WOBBLES THROUGH THE FCST AREA...PRESUMABLY ACTING AS A FOCUS FOR SNOW SHOWERS. OUR BEST GUESS IS 20S NORTH AND 30S SOUTH FOR HIGHS BUT THIS MAY BE TOO COLD. HPC SET TEMPERATURES IN THE 40S AND 50S THURSDAY WITH A COOL DOWN INTO THE 20S AND 30S FRIDAY. THESE GRIDS WERE DISCARDED FOR SOMETHING CLOSER TO CLIMO...ATLEAST ON THURSDAY WHEN IT WAS OBVIOUS A COLD FRONT WOULD DROP THROUGH. CLEARLY THE ECMWF AND GFS ARE WOBBLING THIS FAR OUT IN THE FCST. HOWEVER THE GFS ENSEMBLE SUPPORTS THE COOLER ECMWF. AVIATION... MID CLOUDS CONTINUING TO INCREASE ACROSS ESPECIALLY IN THE KVTN VCNTY THIS AFTERNOON...WITH CEILING HEIGHTS LOWERING WITH TIME. SOUNDING PROFILES INDICATE A SUBSTANTIAL DRY LAYER BELOW 6K FT OR SO THAT WILL NEED TO COOL/MOISTEN BEFORE PRECIP WILL BE REALIZED AT THE SFC. WOULD EXPECT THAT ANY SN WILL BE VERY LIGHT AT BEST AT KVTN...THEREFORE MAIN CONCERN WILL BE POTENTIAL FOR IFR CONDITIONS DUE TO CEILINGS. WITH BETTER FORCING INDICATED AT KVTN THAN KLBF...WET BULB EFFECT SHOULD ALLOW FOR A LOW CLOUD FORMATION BY LATE EVENING THROUGH THE OVERNIGHT HOURS. IN FACT RH TIME HEIGHTS AND SOUNDING PROFILES FROM RUC/NAM/LOCAL WRF ARW SHOULD THE LOWEST LAYER CONTINUING TO BE SATURATED THRU 18Z FOR KVTN. NO PRECIP MENTIONED FOR KVTN SINCE ANY SN WOULD BE VERY LIGHT...BETTER CHANCES FOR MORE FLURRIES FURTHER E. AS FOR KLBF...THOUGH CLOUD HEIGHTS WILL BE LOWERING...MOST SOUNDING PROFILES SHOW CLOUDS REMAINING ABOVE MVFR SO HAVE TRENDED TWD LOWER RANGE OF IFR FOR NOW. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ POWER ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTH PLATTE NE 256 PM CST FRI DEC 5 2008 .DISCUSSION... MID LEVEL COLD FRONT WILL DRAPE THROUGH NCNTL NEB THIS EVENING ACTING AS A FOCUS FOR VERY LIGHT SNOW...POSSIBLY MIXED WITH RAIN BEFORE NIGHTFALL. THIS FRONT WILL DRAPE ACROSS THE NERN PORTION OF THE FCST AREA SATURDAY PRODUCING WIDESPREAD CLOUDINESS AND PERHAPS SOME LIGHT SNOW. THE FRONT AND WARM AIR ADVECTION BEGIN OPERATING SATURDAY NIGHT AS BOTH THE NAM AND GFS INDICATE LIGHT SNOW DEVELOPING SATURDAY NIGHT FOR A TIME. LESS THAN AN INCH OF SNOW IS EXPECTED. FOR SUNDAY...THE WARM AIR WINS OUT AS THE WARM FRONT PUSHES EAST. ALL AREAS SHOULD CLEAR OUT AT THE LOWER LEVELS BUT PERSISTENT MID AND UPPER LEVEL MOISTURE WILL REMAIN ACROSS THE CENTRAL PLAINS. THE WARM AIR SHOULD BE SUFFICIENT FOR TEMPERATURES TO RISE INTO THE 40S ACROSS MOST OF THE AREA WITH 30S IN THE FAR ERN PTN OF THE FCST AREA. MONDAY...A COLD FRONT WILL DROP THROUGH THE FCST AREA. THE ECMWF IS VERY ACTIVE SUGGESTING A FAIRLY WIDESPREAD RAIN-SNOW EVENT MONDAY AND MONDAY NIGHT. THE GFS...NAM12...NOGAPS AND GEM INDICATE THE BEST FORCING WILL BE ACROSS WRN KS AND ERN COLO. THE ECMWF HAS NOT BEEN FULLY DISCOUNTED SO 20 TO 30 POPS BLANKET THE FCST AREA MONDAY AND MONDAY NIGHT. LATER FCSTS CAN RAISE OF LOWER THE POP AS THE MODELS COME INTO BETTER AGREEMENT. THE PROBLEM IS SOME FISHY UPPER LEVEL ENERGY ACROSS THE ERN PAC WHICH SOME MODELS PHASE FARTHER SOUTH VS THE ECMWF WHICH OPERATES FARTHER NORTH. IF THE ECMWF IS WRONG THEN ONLY SWRN NEB WILL GET PCPN FROM THIS SYSTEM. TUESDAY AND WEDNESDAY...TEMPERATURES MODERATE TO SEASONABLE LEVELS AS A WARM FRONT DEVELOPS AND PUSHES EAST ACROSS NEB. THE FCST IS DRY DURING THIS TIME. THURSDAY AND FRIDAY...A WEAK COLD FRONT WOBBLES THROUGH THE FCST AREA...PRESUMABLY ACTING AS A FOCUS FOR SNOW SHOWERS. OUR BEST GUESS IS 20S NORTH AND 30S SOUTH FOR HIGHS BUT THIS MAY BE TOO COLD. HPC SET TEMPERATURES IN THE 40S AND 50S THURSDAY WITH A COOL DOWN INTO THE 20S AND 30S FRIDAY. THESE GRIDS WERE DISCARDED FOR SOMETHING CLOSER TO CLIMO...ATLEAST ON THURSDAY WHEN IT WAS OBVIOUS A COLD FRONT WOULD DROP THROUGH. CLEARLY THE ECMWF AND GFS ARE WOBBLING THIS FAR OUT IN THE FCST. HOWEVER THE GFS ENSEMBLE SUPPORTS THE COOLER ECMWF. && .AVIATION... MID CLOUDS CONTINUING TO INCREASE ACROSS ESPECIALLY IN THE KVTN VCNTY THIS AFTERNOON...WITH CEILING HEIGHTS LOWERING WITH TIME. SOUNDING PROFILES INDICATE A SUBSTANTIAL DRY LAYER BELOW 6K FT OR SO THAT WILL NEED TO COOL/MOISTEN BEFORE PRECIP WILL BE REALIZED AT THE SFC. WOULD EXPECT THAT ANY SN WILL BE VERY LIGHT AT BEST AT KVTN...THEREFORE MAIN CONCERN WILL BE POTENTIAL FOR IFR CONDITIONS DUE TO CEILINGS. WITH BETTER FORCING INDICATED AT KVTN THAN KLBF...WET BULB EFFECT SHOULD ALLOW FOR A LOW CLOUD FORMATION BY LATE EVENING THROUGH THE OVERNIGHT HOURS. IN FACT RH TIME HEIGHTS AND SOUNDING PROFILES FROM RUC/NAM/LOCAL WRF ARW SHOULD THE LOWEST LAYER CONTINUING TO BE SATURATED THRU 18Z FOR KVTN. NO PRECIP MENTIONED FOR KVTN SINCE ANY SN WOULD BE VERY LIGHT...BETTER CHANCES FOR MORE FLURRIES FURTHER E. AS FOR KLBF...THOUGH CLOUD HEIGHTS WILL BE LOWERING...MOST SOUNDING PROFILES SHOW CLOUDS REMAINING ABOVE MVFR SO HAVE TRENDED TWD LOWER RANGE OF IFR FOR NOW. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ CDC/JWS ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 1253 AM EST THU DEC 4 2008 .SYNOPSIS... RAIN ARRIVES TONIGHT AND THURSDAY MORNING WITH A STRONG COLD FRONT. HIGH PRESSURE WITH DRY WEATHER FRIDAY AND FRIDAY NIGHT. CLIPPER SYSTEM WITH MEASURABLE SNOW POSSIBLE THIS WEEKEND. && .NEAR TERM /THROUGH TODAY/... UPDATE...SCATTERED SHOWERS AHEAD OF A COLD FRONT ARE MOVING ALONG THE OHIO RIVER...BUT ARE STRUGGLING TO REACH THE GROUND AS THE ATMOSPHERE IS NOT YET PRIMED WITH CLOUD BASES STILL ABOVE 6000FT. WILL EXPECT RAINFALL COVERAGE TO INCREASE STEADILY OVERNIGHT ACROSS THE WEST AS THE MAIN BAND OF SHOWERS MOVES CLOSER. EXAMINED THE POTENTIAL FOR FREEZING RAIN IN THE VALLEYS OF THE HIGHER ELEVATIONS...BUT SOUNDINGS STILL DO NOT INDICATE A WARM LAYER ALOFT AS THE FORCING ARRIVES...AND FREEZING TEMPERATURES AT THE SURFACE FOR ANY PERIOD OF TIME ARE IFFY RIGHT NOW. PREVIOUS DISCUSSION...CLOUDS ARE MOVING IN FAIRLY QUICKLY AHEAD OF THE APPROACHING COLD FRONT WITH THE RUC13 DOING A GOOD JOB OF PICKING UP ON THE CLOUDS. PRECIPITATION WITH THIS FRONT WILL BE HOLDING CLOSER TO THE FRONTAL SYSTEM. WITH THE CLOUDS COMING IN WELL AHEAD THE TEMPERATURES WILL KEEP ABOVE FREEZING AHEAD OF THE FRONT SO THE SHOWERS WILL BE RAIN RATHER THEN SNOW. THOUGHT ABOUT THE POSSIBILITY OF SOME FREEZING RAIN IN THE MOUNTAINS AS THE RAIN MOVES IN DURING THE MORNING BUT KEPT THE TEMPERATURES ABOVE FREEZING WITH THE INCREASED SOUTHERLY FLOW AND CLOUDS COMING IN. AS A RESULT HAVE KEPT THE PRECIPITATION FORECAST WITH RAIN CHANGING OVER TO SNOW SHOWERS. BACK END OF PRECIPITATION SHUTS OFF FAST AS MOISTURE IS RIGHT WITH THE FRONT SO THE ONLY PLACE ACCUMULATION IS EXPECTED WILL BE IN THE MOUNTAINS WITH AN INCH OR TWO COULD RESULT THURSDAY. TEMPERATURE TRACE FOR THURSDAY WILL BE NONE DIURNAL AS COLD AIR COMES IN DURING THE DAY. LOOKING FOR COLD FRONTAL PASSAGE 13 TO 15Z OHIO RIVER AND AROUND 18Z CRW. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... POPS SHOULD BE DECREASING OVERNIGHT THURSDAY NIGHT...BUT HELD ONTO SOME LIKELY POPS IN THE MOUNTAINOUS COUNTIES EARLY THURSDAY EVENING. WITH 850 THERMAL TROF AROUND MINUS 10C ON FRIDAY AND UPPER AIR DISTURBANCES PASSING DURING THE AFTERNOON AND EVENING...THINKING THEIR COULD BE A MIX OF CLOUDS AT VARIOUS LEVELS BUT NO SIGNIFICANT PRECIPITATION. COULD NOT RULE OUT SOME FLURRIES OR LIGHT SNOW SHOWERS. SOME 20 POPS OVER THE MOUNTAINOUS COUNTIES FOR NOW...BUT EVEN THOSE MINIMUM POPS DROP EVEN LOWER FRIDAY NIGHT INTO EARLY SATURDAY. NO BIG CHANGES ON THE TIMING ON THE LOW PRESSURE MOVING ACROSS THE GREAT LAKES ON SATURDAY AND SATURDAY EVENING...BEFORE CONSOLIDATING AND DEEPENING QUICKLY OFF NEW ENGLAND SUNDAY. WENT LIKELY POP AFTER THE MID LEVEL MOISTURE LOWERS SATURDAY AFTERNOON INTO SATURDAY EVENING. OF COURSE...DURATION OF MID LEVEL MOISTURE SHORTER ACROSS SOUTHERN COUNTIES. EVENT TRANSITIONS INTO WIND BLOWN SNOW SHOWERS AND LOW LEVEL MOISTURE BY DAWN SUNDAY. COULD NOT RULE OUT RAIN OR SNOW SHOWERS IF PCPN REACHES THE GROUND IN THE SOUTHERN LOWLANDS LATE SATURDAY AFTERNOON...OTHERWISE SNOW. HAVE THIS EVENT...LATE SATURDAY AFTERNOON INTO SUNDAY....IN THE HAZARDOUS WEATHER OUTLOOK. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... SURFACE LOW PRESSURE WILL MOVE AWAY ON SUNDAY...ALLOWING HIGH PRESSURE TO BUILD IN FROM THE WEST. GFS BUFKIT SOUNDING FOR KEKN INDICATES SOMEWHAT IDEA CONDITIONS FOR UPSLOPE FLOW AS AIRMASS WILL PLENTY COLD...-12 TO-20 DEGC...AND WINDS WILL BE NORTHWESTERLY. ONLY NEGATIVE THING IS IT APPEARS MOISTURE MAY ALREADY BE DRYING OUT AT THE BEGINNING OF THE PERIOD. HOWEVER...STILL FEEL LIKELY POPS WILL BE WARRANTED...ESPECIALLY ACROSS THE HIGHER TERRAIN OF THE NORTHERN MOUNTAINS. ACROSS THE CENTRAL MOUNTAINS...HAVE 50 POPS WITH LESSOR VALUES ACROSS THE SOUTH. SNOW SHOWERS SHOULD SHUT-OFF LATE SUNDAY AFTERNOON AS HIGH PRESSURE BUILDS IN. MAY BE A FEW HOURS OF SNOW FLURRIES IN THE MOUNTAINS BEFORE IT ENDS. BUT WILL NOT ADD THIS DETAIL AT THIS TIME. THE HIGH WILL SLIDE SOUTHEAST SUNDAY NIGHT...RESULTING IN DRY WEATHER AND SOUTHERLY WINDS. HOWEVER...IT WILL STILL BE BELOW NORMAL TEMPERATURES. ANOTHER SYSTEM WILL PUSH THROUGH ON TUESDAY...DRAGGING A FRONT INTO THE REGION. EXPECT PRECIPITATION ASSOCIATED WITH THIS SYSTEM WILL PUSH IN MONDAY NIGHT. HAVE FOLLOWED HPC THOUGHTS FOR TUESDAY AND WEDNESDAY AS THEY INDICATE THE FRONT WILL BECOME STATIONARY IN OUR VICINITY. AN AREA OF LOW PRESSURE IS FORECAST TO MOVE NORTHEAST ALONG THE FRONT. THE SECOND LOW WILL PULL EAST LATE IN THE PERIOD. HAVE TWEAKED MAXT/MINT GRIDS TO REFLECT LATEST THINKING WITH HPC AND 12 UTC MEX NUMBERS. HAVE ALSO USED MEX COOP MOS TO TWEAK TEMPS AT SNOWSHOE DOWN A FEW DEGREES...ESPECIALLY ON SUNDAY AND SUNDAY NIGHT. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... 06Z THURSDAY THRU 06Z FRIDAY... STRONG COLD FRONT MOVES RAPIDLY EASTWARD ACROSS OUR AREA THIS MORNING. FRONT REACHES OHIO RIVER AROUND 13Z...CKB-CRW LINE AROUND 15Z...AND EKN-BKW LINE AROUND 17Z. AHEAD OF THE FRONT...VFR CEILINGS BECOMING MVFR IN RAIN SHOWERS. BEHIND THE FRONT FOR 3-4 HOURS...MVFR WITH RAIN SHOWERS...MIXING WITH SNOW SHOWERS LOWLANDS...AND CHANGING TO SNOW SHOWERS MOUNTAINS. BY 00Z VFR LOWLANDS...CONTINUED MVFR WITH SCATTERED SNOW SHOWERS/FLURRIES MOUNTAINS. AVIATION OUTLOOK /BEYOND 06Z FRIDAY/...CLIPPER SYSTEM WITH POSSIBLE IFR SNOW SHOWERS SATURDAY NIGHT AND SUNDAY. && .EQUIPMENT... HARDWARE / PART/ FAILURE AT CKB ASOS. CKB WILL HAVE INCOMPLETE OR MISSING SURFACE OBSERVATIONS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KTB/JSH/AAR NEAR TERM...26/AAR SHORT TERM...KTB LONG TERM...JSH AVIATION...JMV EQUIPMENT...KTB oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1254 PM EST THU DEC 4 2008 .SYNOPSIS... A COLD FRONT WILL CONTINUE TO MOVE INTO THE FORECAST AREA FROM THE WEST THROUGH THIS EVENING...BEFORE PUSHING EAST OF THE REGION BY FRIDAY MORNING. ANOTHER FAST MOVING COLD FRONT WILL CROSS THE WESTERN CAROLINAS SUNDAY MORNING...WITH HIGH PRESSURE BUILDING IN BEHIND THE FRONT THROUGH MONDAY. && .NEAR TERM /THROUGH TONIGHT/... IN SPITE OF THE CLOSE PROXIMITY OF THE LEADING EDGE OF THE PRECIP TO THE NC BORDER...NEITHER THE LATEST NAM OR RUC ARE VERY SUPPORTIVE OF BRINGING MUCH RAIN ACROSS THE FORECAST AREA. IT COULD BE THAT BOTH CANNOT SPIN UP PRECIP FAST ENOUGH AS THE UPPER FORCING MOVES ACROSS THE AREA LATER TODAY AND THIS EVENING. WATER VAPOR IMAGERY AND UPSTREAM RADARS SHOW CLEAR EVIDENCE OF THE SHORT WAVE WHICH IS EXPECTED TO MOVE THROUGH LATER IN THE DAY. EVEN THOUGH THIS FEATURE SHOULD WEAKEN THERE SHOULD STILL BE ENOUGH FORCING AND MOISTURE TO BRING SCATTERED TO NUMEROUS SHOWERS. ALTHOUGH SOME TWEAKING HAS BEEN DONE TO THE POP INITIALLY...WILL NOT BE TEMPTED TO LOWER IT BASED ON THE NEW GUIDANCE AND WILL HOLD OUT HOPE FOR THIS WAVE TO BRING THE SHOWERS UP FROM THE SOUTHWEST. INCREASING CLOUDS SHOULD PUT A LID ON THE WARMUP THIS AFTERNOON ESPECIALLY OUT WEST. HIGH TEMPS WERE KNOCKED DOWN A FEW DEGREES BASED ON OBS TRENDS AND NEW GUIDANCE. BEST UPPER FORCING MOVES E WITH WEAK SHORTWAVE AFTER 00Z BUT BROAD UPPER TROF STILL LIES OVER AREA WITH TROF AXIS TO THE W. A WEAK WAVE DEVELOPS ALONG SFC BOUNDARY WHICH KEEPS MOISTURE OVER AREA SO CHANCE POPS LINGER AFTER SUNSET...TAPERING OFF TO FAR SE CWA BY DAYBREAK. IN ANY CASE THIS IS NOT A VERY WET SYSTEM. USED HPC QPF AND EVEN WHERE RAIN DOES FALL... LESS THAN 1/2 INCH EXPECTED W MTNS...LESS THAN 1/4 INCH SE OF MTNS BY EARLY FRI MRNG. LOWS TONIGHT M-U30S IN THE PIEDMONT...20S MTNS. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... AS OF 215 AM THURSDAY...A WK WV OF LOW PRES IS XPCTD TO DEVELOP INVOF THE FL PANHANDLE ALONG A STALLING CDFNT BY FRI MORNING. ALOFT...AN H8 FNT WL BE ORIENTED NE-SW INVOF THE CWA THRU FRI AFTN. THE NAM AND GFS DIFFER ON PLACEMENT AND AVAILABLE MOISTURE W/ THE FNT. THE NAM IS SLOWER...KEEPING AREA IN W/SWLY FLOW...W/ SOME LGT RA ACRS AT LEAST THE SRN 1/3RD OF THE CWA. THE 21Z/03 SREF MEAN IS SIMILAR TO THE NAM. HWVR...EVEN H8 WNDS VEERING TO 270 (A LA 00Z GFS) WOULD COMMENCE DOWNSLOPE DRYING AND CAA. SO I KEPT JUST A SLGT CHC POP FOR THE SRN 1/3RD OF CWA FOR FRIDAY. THERE WILL BE A FAIR AMT OF CLD CVR...SO MAX TEMPS WILL BE GENERALLY IN THE 40S TO LWR 50S. FRI NGT THRU SATURDAY...UPR TROF ACRS THE ERN CONUS AMPLIFIES...AS REINFORCING S/W DIVES SE FM THE UPR MIDWEST TO THE EAST COAST. MODEL SNDGS INDICATING VARYING LAYERS OF MOISTURE IN FAST WLY FLOW. SO PCLOUDY CONDS W/ BLO NORMAL TEMPS CONT (MIN TEMPS IN THE 20S TO LWR 30S AND MAX TEMPS MAINLY IN THE 40S TO LWR 50S). SATURDAY EVE THRU SUNDAY...A POTENT S/W TROF QUICKLY DIVES SE AND CROSSES THE APPALACHIANS OVRNGT SATURDAY. NWLY WNDS INCR AND GUIDANCE GENERALLY AGREES ON THERE BEING A LTL LLVL MOISTURE BRIEFLY W/ PASSAGE OF LLVL TROF. INHERITED POPS/TEMPS LUK GOOD...SO FEW CHANGES WERE MADE. BASICALLY...A LOW-END CHC OF SNOW SHWRS ALONG THE TN/NC BORDER SATURDAY NGT...TAPERING OFF BY MIDDAY SUNDAY. TEMPS BLO NORMAL. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... AS OF 215 AM THURSDAY...THE FIRST PORTION OF THE MEDIUM RANGE WILL BE QUIET WITH HIGH PRESSURE BUILDING INTO THE SOUTHERN APPS FROM THE NORTHWEST MONDAY NIGHT...THEN GRADUALLY TRANSLATING OFF THE EAST COAST BY TUESDAY MORNING. THE MAIN FOCUS OF THE PERIOD WILL BE THE DEVELOPING LOW PRESSURE SYSTEM THAT MOVES ACROSS THE SOUTHERN MS VALLEY ON TUESDAY. A SHARP AND VIGOROUS UPPER TROF SWINGS SOUTHEASTWARD OUT OF THE NORTHERN ROCKIES AND TAKES ON A NEAR NEUTRAL TO NEGATIVE TILT ACROSS THE DEEP SOUTH TUESDAY NIGHT ACCORDING TO THE 00Z GFS. OVERALL THE GFS SEEMS TO HAVE SHOWN CONSIDERABLE RUN TO RUN INCONSISTENCY CONCERNING THE AMPLITUDE AND TRACK OF THE UPPER WAVE...AND SUBSEQUENTLY THE STRENGTH AND TRACK OF THE SURFACE LOW. FURTHERMORE...THE GFS AND ECMWF ARE STILL AT ODDS WITH THE EVOLUTION OF THIS SYSTEM AS THE 00Z ECMWF IS ABOUT A FULL 24 HOURS SLOWER THAN THE GFS CONCERNING THE POSITION OF THE SURFACE LOW AT 12Z WEDNESDAY. THE CURRENT RUN OF THE GFS APPEARS TO FAVOR A POTENTIAL QLCS SEVERE WX THREAT ACROSS THE FA AS IT PUSHES A STRONG COLD FRONT ACROSS THE AREA TUESDAY EVENING. WITH PLAN VIEW CAPE VALUES OF 100-200 J/KG AND 0-3 KM SHEAR OF 40-50 KTS ALONG AND NEAR THE I-77 CORRIDOR...THE NEAR STORM ENVIRONMENT WOULD CERTAINLY SUPPORT QLCS DEVELOPMENT. HOWEVER...THIS SHOULD PERHAPS BE TAKEN WITH A GRAIN OF SALT THIS FAR OUT AS THE GFS HAS SHOWN RUN TO RUN INCONSISTENCY WITH A POTENTIAL WINTER STORM IN THE PREVIOUS RUN AND NOW A SEVERE WX THREAT. IN SUMMARY...GIVEN THE SIGNIFICANT DIFFERENCES IN THE AVAILABLE MODEL GUIDANCE...THERE IS VERY LOW CONFIDENCE IN THE FORECAST AT THIS TIME. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... MAIN ISSUE FOR THE TAFS WILL BE THE LOW CLOUD COVER OVER THE NEXT 12 TO 18 HOURS. SATELLITE IMAGERY AND OBS SHOW MVFR CEILINGS ACRS N GA AND ERN TN BUT THERE IS SOME UNCERTAINTY AS TO HOW FAR E THE MVFR WILL GET THIS AFTERNOON AND EVENING. KAVL SHOULD BE IN AND OUT OF THE MVFR THROUGH THE EVENING...BUT OTHER TAF SITES WILL ONLY FLIRT WITH IT. DEEPER AND DRIER BOUNDARY LAYER EAST ACROSS UPSTATE SC AND THE NC PIEDMONT WILL PROBABLY KEEP THE CLOUD BASE IN THE LOW END OF THE VFR CATEGORY...BUT LOW ENOUGH TO IMPACT OPERATIONS...IN THE 3500 TO 4500 FOOT RANGE. THE PROBLEM IS WITH THE SW TO W FLOW ALOFT THERE IS NO MECHANISM LIKE UPSLOPE OR UPGLIDE TO DEVELOP OR MAINTAIN THE CLOUD DECK OVER THE PIEDMONT. FOR THAT REASON...THINK THE MOST LIKELY CEILING AT KCLT WILL BE JUST ABOVE 3000 FEET SO THAT WILL BE CARRIED IN THE TAF. MVFR IS CERTAINLY POSSIBLE...BUT MY CONFIDENCE IS NOT HIGH ENOUGH TO PUT IT IN A TEMPO. IF IT DOES HAPPEN...THE MOST LIKELY TIME WOULD BE 22Z-04Z. THE FRONT SHOULD MOVE OVER KCLT IN THE EARLY EVENING AS WELL. GLAD TO SEE NEW LAMP GUIDANCE COMING AROUND TO A LATER WIND SHIFT...MOST LIKELY AFTER 01Z. SUBSEQUENT AMENDMENTS TO KCLT WILL SUPPORT THE TREND TO A LATER SHIFT TO NW WIND IF IT CONTINUES...AND WILL RE-ADDRESS THE MVFR CEILING POTENTIAL. LOW CLOUDS WILL BE OVER ALL TAF SITES FOR THE BETTER PART OF THE NIGHT AND SHOULD BREAK UP FROM WEST TO EAST DURING MID MORNING FRIDAY. ALL SITES SHOULD BE VFR FROM 16Z ONWARD WITH A NORTH OR NORTHEAST WIND. OUTLOOK...HIGH PRESSURE WILL BUILD OVER THE AREA FRI. A COLD FRONT WILL CROSS THE REGION SAT WITH A FEW SHOWERS AND CIG/VSBY RESTRICTIONS PSBL INTO SUN MRNG. HI PRES REBUILDS SUN NIGHT-MON. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...SBK NEAR TERM...PM/RB SHORT TERM...ARK LONG TERM...BSH AVIATION...PM sc AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 855 PM CST FRI DEC 5 2008 .DISCUSSION... MIXING BEHIND SURFACE WARM FRONT/SWITCH TO MORE WESTERLY WINDS HAS ALLOWED TEMPERATURES OVER MUCH OF THE CWA TO CONTINUE RISING THIS EVENING...WITH MUCH OF THE WESTERN AND SOUTHERN CWA ABOVE FREEZING AS OF 02Z. COLDER AIR STILL POISED TO OUR NORTH...AND IS EXPECTED TO MAKE THE SOUTHWARD PUSH LATER TONIGHT SURFACE LOW IN NORTHERN MN MOVES INTO THE WESTERN GREAT LAKES...AND COLD FRONT IN FAR SOUTHEAST ND MOVES SOUTH THROUGH THE AREA. HAVE MADE QUITE A FEW ADJUSTMENTS TO HOURLY TEMPS TO SHOW NEARLY STEADY OR EVEN SLIGHTLY RISING TEMPS YET THROUGH THE BALANCE OF THE EVENING...WITH SHARPER DECLINE LATER IN THE NIGHT AS THE COLD FRONT PUSHES SOUTH. BUMPED UP OVERNIGHT LOWS 2-4 DEGREES OVERALL...WITH LOWS EXPECTED NEAR THE END OF THE VERIFICATION PERIOD TOWARD 14Z...THOUGH READINGS WILL LIKELY STILL FALL A LITTLE MORE THROUGH THE MIDDLE OF THE MORNING HOURS BEFORE A SUBTLE REBOUND IN THE AFTERNOON. AS FOR PRECIP...BATCH OF LIGHT SNOW WHICH PASSED THROUGH MAINLY THE NORTHEAST CWA WITH THE UPPER WAVE IS PUSHING OUT OF THE AREA...WITH BOTH THE 00Z NAM AND RUC MAINTAINING PUSH OF DRIER MID LEVEL AIR ACROSS THE CENTRAL AND NORTHEAST CWA THROUGH THE REMAINDER OF THE NIGHT. HAVE CUT BACK POPS AS A RESULT...HANGING ONTO A SLIGHT CHANCE IN THE FAR SOUTHWEST AFTER 06Z WHERE DEEPER MOISTURE PERSISTS SOUTHWEST OF THE COLD FRONT. UPDATED GRIDS/PFM/ZFP HAVE BEEN SENT. && .AVIATION... LIGHT SNOW IS LOOKING LESS LIKELY TONIGHT ACROSS THE AREA AS RADAR IMAGES SHOWING DRIER AIR WORKING INTO THE REGION. NORTHWESTERLY WINDS WILL INCREASE THROUGH THE NIGHT AS A COLD FRONT SLIDES THROUGH THE NORTHERN PLAINS. CEILINGS WILL VARY FROM VFR TO MVFR THROUGH THE LATE EVENING...THEN TREND TOWARD A MORE WIDESPREAD MVFR DECK AFTER 06Z AS MOISTURE POISED TO THE NORTH COMES SOUTHWARD. SOME DISCREPANCY AMONG MODEL GUIDANCE WITH RESPECT TO HOW QUICKLY MVFR CIGS BREAK UP ON SATURDAY MORNING...WITH SOME SUGGESTING THE LOW LEVEL MOISTURE HOLDING THROUGH 18Z. WITH THE UNCERTAINTY...PUT SCATTERED 2500 FT AT TAF SITES AFTER 15Z ON SATURDAY. && .PREV DISCUSSION... TEMPERATURES HAVE CLIMBED NICELY THIS AFTERNOON ON A MODERATELY STRONG SOUTHWEST WIND...WITH MOST LOCATIONS WELL INTO THE MID AND UPPER 20S...EVEN SOME LOW TO MID 30S FROM NORTHWEST IOWA WEST THROUGH THE MISSOURI VALLEY. THIS IS IN RESPONSE TO THE WAVE DIVING SOUTH INTO THE REGION TONIGHT. INITIALLY...THIS ENERGY WILL NEED TO OVERCOME A VERY DRY LAYER OF AIR FROM ABOUT 925-800MB. LOOKS LIKE WE WILL OVERCOME THIS FOR A BRIEF PERIOD...WITH THE BEST CHANCES FOR SNOW AROUND HON FROM ABOUT 22Z THROUGH 1Z...FSD FROM ABOUT 0Z-3Z AND SUX...WHICH SHOULD BE ON THE SOUTHERN EDGE...FROM ABOUT 2Z-5Z. WENT WITH SOME NON-DIURNAL FALLS FOR TEMPERATURES TONIGHT AS WINDS AND CLOUD COVER WILL LIKELY KEEP TEMPERATURES UP THROUGH THE EVENING AND EARLY OVERNIGHT HOURS...THEN MUCH COLDER AIR WILL START TO WORK INTO NORTHERN PARTS OF THE CWA BY ABOUT 10Z...WITH FALLING TEMPERATURES FOR MOST LOCATIONS THROUGH TOMORROW MORNING. LOWS THROUGH EARLY TOMORROW MORNING WILL LIKELY RANGE FROM NEAR 10 NORTH TO THE UPPER TEENS SOUTH. CLEARING MAY BE PRETTY STG ERN PART OF FCST AREA SAT DESPITE NAM TYPICALLY WANTING TO LINGER LO LV MOISTR OVER AREA. AS HIGH APPROACHES AND RIDGES INTO AREA SUBSDNCE SHOULD TAKE OVER. SOME CLOUDS SHOULD LINGER ERN PART OF FCST AREA ESPLY IN THE SW. MEANWHILE...TEMPERATURES WHICH WILL STILL BE FALLING IN ERY MRNG WILL NOT DO TOO MUCH RECOVERING AND HIGHS SOME AREAS MAY ACTUALLY BE IN ERY MRNG PREDAWN TIME WITH DAYTIME WARMING ONLY ALMOST COMPENSATING FOR CONTD MORNING FALL. WITH WINDS DROPPING OFF QUICKLY TEMPS WILL DROP WELL ERN FCST AREA SUN EVE AND EVEN A LTL THERE AFTER MIDNIGHT...AS TEMPS IN THE W LVL OFF SAT EVE AND BEGIN TO WARM SLWLY AFTER MIDNIGHT. STG LO LVL WARM ADVECTN PATTRN EXPECTED TO RESULT IN A BROAD BAND OF LGT SNOW WHICH SHOULD MOVE EWD/NEWD ACRS AREA LATE SAT NGT AND SUN MRNG. SOME OF THIS WILL STILL BE LEFT IN THE NORTHEAST FOR SUN AFTN BUT SHUD BE MOSTLY OUT BY LATE IN THE DAY. IN FACT...HAVE KEPT THE PCPN AS SNOW AS THINKING IS THAT PCPN WILL BE MOVING OUT BEFORE IT GETS WARM ENUF FOR FREEZING RAIN. NOT TOO EXCITED ABOUT ANY AMOUNTS AT THIS TIME WITH THERMAL SUPPORT AND LIFT NOT EXPECTED TO BE VERY DEEP...THAT IS WONT GO TOO FAR UP INTO MID LEVELS. SFC TEMPS WILL WARM INTO THE 20S MOST OF FCST AREA SUN AND IN THE LOW TO MID 30S SW. SUN NGT THRU TUE PERIOD PRESENTS INCRG PROBLEMS WITH DIFFERENCES IN MODEL SOLUTIONS. FOR NOW FAVOR GFS SOLUTION OF A GENERALLY DRY PD. ECMWF HINTS AT SIGNFCNT SNOW EVENT PSBL FOR SERN FCST AREA BY SOMEHOW BRINGING THE UPPER LOW COMING ACRS CA/BAJA BORDER AREA SUN NEWD FAR ENUF TO AFFECT FCST AREA. FOR NOW FAVOR GFS/NAM/CANADIAN SOLUTION OF THE DRY FCST BUT WILL HAVE IN A SLGT CHC FOR MON IN DEFERENCE TO THE ECMWF. NOGAPS MODEL IN A LTL DIFFERENT WAY TRIES TO BRING AN AREA OF LGT SNOW UP TO FCST AREA AS WELL. MON SHUD BE RELTVLY MILD ON TEMPS THEN COOLING FOR TUE. WED THRU FRI PERIOD PRESENTS EVEN MORE WIDELY DIFFERENT MODEL SOLUTIONS AND WILL CONT TO LEAN TO THE COLDER GFS WHICH IS IN LINE WITH WHAT WE HAVE BEEN GOING FOR ON TEMPS. AS FOR PCPN...MENTION OF LGT SNOW WITH LOW POPS AS PER HPC GUIDNCE SEEMS IN ORDER BOTH WITH MIDWEEK CDFNT AND IN COLD AIR BEHIND IT...AT LEAST FOR NOW AND TILL WE GET INDICATIONS OF DECENT SFC RIDGING IN COLD AIR WHICH WE DONT HAVE NOW. 00Z CANADIAN HAD A MOST INTERESTING SOLUTION OF WARMING IT UP ALREADY ON FRI THEN HITTING THE AREA WITH A PSBLY MAJOR SNOWSTORM FOR THAT FOLLOWING WEEKEND. THAT SEEMS A LTL GUNG HO BUT AT LEAST THE MODELS ARE STARTING TO SHOW A PATTERN STARTING ABOUT THEN WHICH WILL BE MUCH MORE ACTIVE THAN WE HAVE HAD SO FAR THIS COLD SEASON. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ JH/JM sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 1031 AM CST FRI DEC 5 2008 .UPDATE... MSAS SHOWS SFC TROF IS PROGRESSING SOUTHWARD AS FORECASTED...WITH NW WINDS PICKING UP BEHIND SYSTEM. RUC IS SHOWING FAIRLY IMPRESSIVE 85H THETA-E FORCING ASSOC WITH SFC TROF...COUPLED WITH INCREASE OMEGA IN THE 85H-7H AND 7H-5H LAYERS. LIGHT SNOW LOOKS TO BE A FAIRLY GOOD BET...AND HAVE UPPED POPS FOR MUCH OF THE NORTH AND EAST FOR THIS AFTERNOON. DOESN`T LOOK TO BE MUCH FOR ACCUMS AS DRY AS THE SYSTEM IS...BUT SHOULD BE EFFECIENT AT MAKING SNOW. CURRENT FCSTD HIGHS SEEM REASONABLE GIVEN STRENGTH OF LOW LEVEL WAA QUICKLY MOVING IN. UPDATED WORDED ZONES HAVE BEEN SENT. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH SUNDAY PRECIPITATION CHANCES LATER THIS AFTERNOON IS THE MAIN FORECAST CHALLENGE IN THE SHORT TERM. CURRENTLY THERE IS A BAND OF HIGH CLOUDS MOVING ACROSS CENTRAL ND...AND INTO WESTERN SOUTH DAKOTA. THESE HIGHS CLOUDS ARE ERODING THE LOW CLOUDS WITH KABR REPORTING CLEAR SKIES AS OF 8Z. KATY HOWEVER IS STILL REPORTING OVERCAST SKIES. THE AREA OF LOW PRESSURE THAT WILL BRING SNOW BACK INTO THE CWA THIS AFTERNOON IS CURRENTLY SITUATED ALONG THE MONTANA...CANADIAN BORDER. MODELS AGREE WELL WITH BRINGING THIS LOW PRESSURE ACROSS NORTHERN NORTH DAKOTA THIS AFTERNOON...AND THEN OVER LAKE SUPERIOR TONIGHT. NOW COMES THE FORECAST CHALLENGE AS TO WHEN WILL IT SNOW TODAY? AS THE LOW TRACKS OVER NORTHERN NORTH DAKOTA TODAY...WINDS AT 850 MBS SHIFT TO THE WEST WITH MID LEVEL RH VALUES FALLING BELOW 30 PERCENT. MODEL SOUNDINGS OVER KMBG IS MOIST ENOUGH TO SEE SNOW BEGINNING AROUND 18Z. BUFKIT SHOWS THE BEST TIMING FOR SNOW TO BEGIN AROUND 21Z IN KABR AND KPIR. KATY IS MOIST ENOUGH FOR SNOW CLOSER TO 0Z. THIS WILL LIKELY BE ONE OF THOSE EVENTS WHERE WE HIGH POPS WITH LOW QPF AS THERE IS NOT MUCH IN THE WAY OF MID LEVEL FORCING. THERE IS SOME JET SUPPORT AT 300 MBS TONIGHT IN THE FORM OF 130 KT JET STREAK. SNOWFALL AMOUNTS FROM THIS SYSTEM WILL GENERALLY RANGE FROM AN INCH OR LESS...PER THE CARIBOU SNOWFALL AMOUNT TOOL. HIGH PRESSURE NOSES INTO THE NORTHERN PLAINS ON SATURDAY WITH DRIER AIR PUSHING IN AT THE MID LEVELS. UNFORTUNATELY THERE LOOKS TO BE MOISTURE TRAPPED IN THE LOWER LEVEL LEAVING ME TO BELIEVE WE WILL SEE AT LEAST PARTLY CLOUDY SKIES ACROSS THE CWA. WARM AIR IN THE MID LEVELS BEGIN TO PUSH INTO WESTERN SOUTH DAKOTA SATURDAY NIGHT WITH AN OVERRUNNING PRECIPITATION EVENT TAKING PLACE. MODELS HAVE BEEN CONSISTENT IN SHOWING THIS EVENT TAKING PLACE ON SATURDAY NIGHT AND INTO SUNDAY MORNING...FOR THE PAST FIVE MODEL RUNS. THE WARM AIR AT THE MID LEVELS BEGINS TO MIX DOWN TO THE SURFACE ON SUNDAY WITH TEMPS REACHING THE MID TO UPPER 30S IN WEST CENTRAL SOUTH DAKOTA. .LONG TERM...SUNDAY NIGHT THROUGH THURSDAY THE LONG RANGE MODELS...PARTICULARLY THE GFS AND ECMWF REMAIN QUITE SIMILAR IN THEIR DEPICTIONS OF THE LONG WAVE PATTERN THROUGH 180 HOURS. THAT PATTERN BASICALLY COMPRISED OF A MID LEVEL WEST COAST RIDGE AND DOWNSTREAM CENTRAL/EASTERN CONUS TROF. THIS OF COURSE PLACES THE ABR CWA IN A PESKY NORTHWEST FLOW SITUATION WITH A MEAN BAROCLINIC ZONE HANGING AROUND THE AREA. SO...NEEDLESS TO SAY TIMING OF PCPN AND COLD AIR INTRUSIONS ARE SOMEWHAT CHALLENGING. KEPT PCPN CHANCES FOR SUNDAY NIGHT INTO MONDAY WITH BOTH THE GFS AND ECMWF INDICATING SOME POTENTIAL FOR SNOW. THEN WENT DRY UNTIL LATER IN THE WEEK. AT THAT TIME ANOTHER STRONGISH LOOKING CLIPPER IS EXPECTED TO TRACK ACROSS THE NORTHERN PLAINS. AS FOR TEMPERATURES...NEAR TO SLIGHTLY BELOW NORMAL SHOULD SUFFICE FOR THE FIRST PART OF THE EXTENDED. BUT BY THURSDAY A MORE ROBUST CHUNK OF ARCTIC AIR SHOULD SLIDE DOWN INTO THE REGION...ESPECIALLY THE EASTERN CWA. LOOKING A BIT FURTHER OUT...BOTH THE ECMWF/GFS SHOW A PRETTY BIG CHANGE IN THE PATTERN...WITH A WEALTH OF COLD AIR BEGINNING TO WELL UP OVER WESTERN CANADA AS THE MID LEVEL PATTERN GOES THROUGH A RETROGRESSIVE PHASE. COULD THE MIDDLE OF THE MONTH BE COLD AND STORMY? && .AVIATION... A FEW LINGERING MVFR CIGS OVER EASTERN SOUTH DAKOTA SHOULD GRADUALLY BREAK UP THIS MORNING WITH THE REST OF THE MORNING AND EARLY AFTERNOON FEATURING CLOUDS MOSTLY AOA 10K FEET. HOWEVER...BY LATE AFTERNOON AND EARLY EVENING MVFR CIGS ARE EXPECTED TO ROLE SOUTH OVER THE REGION...AND SNOW SHOWERS COULD OCCASIONALLY CAUSE IFR/MVFR VSBYS AT ALL TERMINAL SITES. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...HINTZ SHORT TERM...SD LONG TERM...TDK AVIATION...TDK WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 221 PM CST FRI DEC 5 2008 .DISCUSSION...THE LATEST KBRO RADAR REFLECTIVITY SHOWS THE PATCHY LIGHT DRIZZLE CONTINUING OVER THE EASTERN PORTIONS OF THE BRO CWA AND OFFSHORE OVER THE GULF WATERS. THIS PESKY ACTIVITY WILL PERSIST ALONG THE COASTAL AREAS INTO THIS EVENING AS THE CURRENT RUC GUIDANCE SHOWS WEAK SURFACE TROFFING CONTINUING INTO THE EARLY EVENING EVENTUALLY DISSIPATING LATE TONIGHT DIMINISHING THE LOW LEVEL CONVERGENCE. OVER THE NEXT SEVERAL DAYS...THE BROAD 500 MB TROFFING OVER THE EASTERN U.S. WILL WEAKEN ALLOWING A MORE ZONAL PATTERN TO RE-ESTABLISH OVER THE LOWER 48 STATES. THIS WILL ALLOW THE WAA TO STRENGTHEN AND THE DAYTIME HEATING TO INCREASE OVER THE REGION RESULTING IN WARMING TEMPS THROUGH MON. THE MAV AND MET FORECAST TEMPS AND POPS THROUGH MON MORNING ARE IN PRETTY GOOD AGREEMENT AND WILL NOT DEVIATE FROM THIS TREND TOO MUCH IN THE SHORT TERM. EARLY NEXT WEEK...A 500 MB CLOSED LOW CURRENTLY OVER THE SOUTHERN CA COASTLINE WILL OPEN UP AND PHASE WITH A SHORT WAVE DIGGING SOUTHEAST ACROSS THE PACIFIC NORTHWEST. THIS WILL RESULT IN INCREASED 500 MB TROFFING OVER THE SOUTH CENTRAL PLAINS STATES NEXT MON AND TUES AND THIS WILL PUSH THROUGH ANOTHER STRONG COLD FRONT THROUGH THE REGION NEXT TUES. SO FAR...BOTH THE ECMWF AND THE GFS SHOW DECENT AGREEMENT IN THE HANDLING OF THIS FEATURE WITH THE GFS SHOWING A LITTLE FASTER EASTWARD PROGRESSION OF THE 500 MB LOW/TROUGH VERSUS THE ECMWF. RUN TO RUN CONSISTENCY WITH THE GFS IS OK FOR TEMPS AND WORSE FOR POPS WITH THE LATEST GFS MEX TRYING TO HOLD ONTO THE SLGT CHC/CHC POPS INTO WED. DUE TO THE DECENT AGREEMENT SHOWN IN THE LONGER RANGE PERIOD...WILL STICK FAIRLY CLOSE TO THE CURRENT GFS MEX NUMBERS WITH THE EXCEPTION OF THE POPS FOR MON. THE INCREASE SHOWN IN THE POPS ON WED IN THE LATEST MEX RUN MAY LOWER IN THE NEXT RUN...SO MY CONFIDENCE IN POPS FOR NEXT WED IS PRETTY LOW. && .AVIATION...NORTHERLY WINDS AT THE SURFACE...AND SOUTHWESTERLY WINDS IN THE MIDDLE LAYERS OF THE ATMOSPHERE...WILL PRODUCE VFR/MVFR SKIES AND LIGHT TO MODERATE WINDS THROUGH TONIGHT. SKIES WILL THEN RAPIDLY CLEAR AROUND SUNRISE SATURDAY MORNING AS THE MID-LEVEL FLOW SHIFTS TO THE NORTHWEST. && .MARINE...BUOY 42020 REPORTED NORTHEAST WINDS AROUND 19 KNOTS GUSTING TO AROUND 23 KNOTS WITH SEAS SLIGHTLY UNDER 8 FEET WITH A 7 SECOND PERIOD AT 11 CST/17 UTC. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE GULF OF MEXICO WATERS EAST OF PADRE ISLAND UNTIL 6 PM CST THIS AFTERNOON DUE TO STRONG WINDS AND ROUGH SEAS OFFSHORE. HIGH PRESSURE BUILDING SOUTH INTO TEXAS WILL PRODUCE MODERATE WINDS AND SEAS ALONG THE LOWER TEXAS COAST TONIGHT THROUGH SATURDAY. MARINE CONDITIONS WILL BRIEFLY IMPROVE SATURDAY NIGHT AS HIGH PRESSURE MOVES OVER DEEP SOUTH TEXAS AND THEN FARTHER EAST...WITH WINDS AND SEAS INCREASING SUNDAY AND MONDAY AS IT INTERACTS WITH LOW PRESSURE OVER TEXAS. WINDS AND SEAS WILL CONTINUE TO INCREASE TUESDAY AS A COLD FRONT SWEEPS THROUGH. A SMALL CRAFT ADVISORY MAY BE NEEDED MONDAY THROUGH WEDNESDAY DUE TO STRONG WINDS AND ROUGH SEAS AHEAD OF...AND BEHIND...THE COLD FRONT. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 52 71 55 75 / 20 10 0 0 BROWNSVILLE 49 70 54 78 / 20 10 0 0 HARLINGEN 47 70 52 77 / 10 10 0 0 MCALLEN 48 73 53 77 / 10 10 0 0 RIO GRANDE CITY 48 71 53 76 / 10 10 0 0 SOUTH PADRE ISLAND 56 69 57 71 / 20 10 0 0 && .BRO WATCHES/WARNINGS/ADVISORIES...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR GMZ150-155-170-175. && $$ THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT: HTTP://WWW.WEATHER.GOV/BROWNSVILLE SYNOPTIC/GRIDS...60 MARINE/AVIATION...66 MESO/NOWCASTING...MARTINEZ tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 1126 AM CST FRI DEC 5 2008 .DISCUSSION... SEE AVIATION DISCUSSION BELOW. && .AVIATION... LIGHT SOUTHEAST WINDS ARE SWINGING AROUND TO THE SOUTH AND SOUTHWEST AT THE MOMENT...AND WILL CONTINUE TO VEER AROUND OVERNIGHT EVENTUALLY BECOMING NORTHWESTERLY TOMORROW AS A WEAK COLD FRONT MOVES THROUGH THE AREA. NO RAIN AND FEW CLOUDS ARE EXPECTED WITH THE FRONT AS ITS MAIN IMPACT WILL BE ON THE WIND DIRECTION. HENNIG && .PREV DISCUSSION... /ISSUED 938 AM CST FRI DEC 5 2008/ UPDATE... UPDATED THE FORECAST FOR THE EXPIRATION OF THE HIGH WIND WARNING. DISCUSSION... THE PRESSURE GRADIENT HAS BEEN DIMINISHING AND IT IS SHOWING IN THE GDP OBS. HAVE ALLOWED THE HIGH WIND WARNING TO EXPIRE...AND HAVE UPDATED ALL RELEVANT PRODUCTS. OTHERWISE THE ONGOING FORECAST LOOKS GOOD FOR NOW. HENNIG PREV DISCUSSION... /ISSUED 500 AM CST FRI DEC 5 2008/ DISCUSSION... EARLY MORNING SURFACE ANALYSIS CONTINUING TO DEPICT A WELL DEVELOPED SURFACE RIDGE EXTENDING INTO WEST TEXAS AND SOUTHEAST NM FROM A PARENT HIGH LOCATED ACROSS NORTH-CENTRAL OK. PRESSURE GRADIENT IN ASSOCIATION WITH FEATURE HAS KEPT A STEADY NORTHEASTERLY WIND THIS MORNING...ULTIMATELY CREATING HIGH WIND WARNING CONDITIONS ACROSS GUADALUPE PASS. LATEST OBS FROM KGDP INDICATE WINDS BLOWING JUST ABOVE WARNING CRITERIA AND BASED ON WIND FORECASTS FROM BOTH THE WRF AND RUC...FAVORABLE NORTHEASTERLY TRAJECTORY WILL CONTINUE THROUGH THE MID MORNING. BASED ON THIS...HAVE DECIDED TO EXTEND THE WARNING THROUGH 15Z...AFTER WHICH WINDS WILL QUICKLY DECEASE AS THE SURFACE FLOW BEGINS TO VEER MORE SOUTHEASTERLY. AFOREMENTIONED RIDGE AXIS REMAINING IN PLACE ACROSS THE REGION TODAY ENSURING ANOTHER DAY OF WELL BELOW NORMAL TEMPS. CURRENT CONDITIONS UPSTREAM SHOW LOW TO MID TEEMS ACROSS NORTHEASTERN KS THIS MORNING...AN INDICATION OF JUST HOW COOL THE AIRMASS IS. WITH THIS IN MIND...HAVE DECIDED TO KEEP TEMPS IN THE LOW TO MID 40S ACROSS MUCH OF THE PERMIAN BASIN TODAY...AS REINFORCED COLD AIR WILL CONTINUE TO SETTLE INTO THE AREA AS SIGNALED BY COOLER H85 TEMPS ALOFT. WITH HIGHS YESTERDAY ONLY CLIMBING INTO THE MID TO UPPER 40S ACROSS MUCH OF THE REGION...FEEL BASING THE CURRENT FORECAST ON PERSISTENCE IS THE WAY TO GO. ALOFT...A HIGHLY SHEARED POSITIVELY TILTED TROUGH WILL PASS OVERHEAD TODAY...YIELDING NOTHING MORE THAN ENHANCED CLOUDINESS ALOFT BEFORE GRADUALLY CLEARING LATE THIS AFTERNOON AND EVENING FROM NORTHWEST TO SOUTHEAST. OVERNIGHT TONIGHT...A SURFACE PRESSURE TROUGH ORIGINATING FROM THE SOUTHERN ROCKIES WILL BEGIN TO WORK ITS WAY EASTWARD...WITH CONTINUATION ACROSS THE REGION THROUGH TOMORROW AFTERNOON. BEHIND THE FEATURE...LOW-LEVEL FLOW WILL BECOME MORE NORTHWESTERLY AS THE AFTERNOON PROGRESSES...SUGGESTING SOME DOWNSLOPE COMPRESSIONAL WARMING POTENTIAL ACROSS PORTIONS OF THE AREA. THIS IN COMBINATION WITH WARMING TEMPS ALOFT WILL SUPPORT NEAR NORMAL TEMPS ACROSS MUCH OF THE REGION TOMORROW...WITH LOW TO MID 60S LIKELY RETURNING. PERIOD OF TRANSITION EXPECTED BY SUNDAY AS A STUBBORN UPPER LOW OFF THE CA COAST BEGINS TO WORK EAST INTO THE DESERT SW/NORTHERN MEX. NORTHWESTERLY MID-LEVEL FLOW WILL GRADUALLY BECOME MORE ZONAL WITH TIME IN ADVANCE OF THIS FEATURE...WITH EMBEDDED SHORTWAVES EXPECTED TO APPROACH WEST TX/SE NM BEGINNING SUN AFTERNOON. INCREASING WESTERLY FLOW ALOFT WILL LEAD TO ENHANCED LEESIDE TROUGHING...WITH TROUGH AXIS EXPECTED TO EXTEND SOUTHWARD ACROSS THE SOUTHEAST NM PLAINS AND WEST TX MOUNTAINS. STRONG WARM AIR ADVECTION EXPECTED ACROSS THE REGION WITH RISING H85 TEMPS THROUGH THE AFTERNOON. FAVORABLE MIXING ALSO ANTICIPATED AS LOW-LEVEL LAPSE RATES BECOME NEARLY DRY ADIABATIC. ONLY CAVEAT WITH INCREASING TEMPS SIGNIFICANTLY WITH THIS MORNING/S UPDATE IS THE EXPECTATIONS OF INCREASING MID AND HIGH LEVEL CLOUDS. IN ANY EVENT...FORECASTED H85 TEMPS SUPPORT LOW TO MID 70S ACROSS MUCH OF THE REGION...HOWEVER WITH CONCERNS REGARDING CLOUDS...HAVE ATTEMPTED TO PLAY IT SAFE AND ONLY RAISE TEMPS A FEW DEGREES FOR NOW PENDING LATER MODEL RUNS. UNSETTLED WEATHER CONTINUING INTO THE EARLY WORK WEEK AS LEESIDE TROUGH/SFC LOW EXITS THE SOUTHERN ROCKIES AND SETTLES INTO THE CENTRAL TX PANHANDLE BY 00Z TUE. ACROSS THE MID-LEVELS...AN UPPER TROUGH IS EXPECTED TO SWING INTO THE REGION AS WELL...WITH THE ECMWF BEING THE MOST BULLISH OF MID-RANGE GUIDANCE. MODELS IN RELATIVELY GOOD AGREEMENT THAT A WELL DEFINED DRYLINE WILL SUPERSEDE THE LOW...HOWEVER FEATURE IS EXPECTED TO GRADUALLY MOVE EASTWARD THROUGHOUT THE DAY AS THE LOW SINKS SOUTHWARD TRAPPING THE BEST RETURN FLOW MOISTURE WELL OFF TO THE EAST OF THE CWA. DESPITE THIS...MODELS DO DEVELOP PRECIP ACROSS THE REGION AS AN UPPER SPEED MAX MOVES ACROSS THE REGION ALONG WITH APPRECIABLE SHORTWAVE ENERGY. HAVE RAISED POPS TO JUST UNDER MENTIONABLE LIMITS FOR NOW BASED ON COLLABORATION WITH ADJACENT OFFICES WHILE AWAITING FOR RUN TO RUN MODEL MODEL CONTINUITY. STRONG COLD FRONT EXPECTED ACROSS THE AREA EARLY TUESDAY MORNING WITH CONTINUED ACCELERATION TO THE SOUTH THROUGH THE DAY. COLD HIGH PRESSURE BUILDING IN BEHIND THE FRONT WILL LEAD TO COOLER TEMPS HOWEVER TEMPS WILL LIKELY REBOUND ON WED BEFORE ANOTHER REINFORCING SHOT OF COLD AIR ARRIVES ON THU. GENERALLY USED A GFS/ECMWF BLEND FOR THE EXTENDED AS MINOR DIFFERENCES AT THE START OF THE PERIOD IRONED THEMSELVES OUT AS THE FORECAST PERIOD ADVANCED. && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...NONE. && $$ 10 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 938 AM CST FRI DEC 5 2008 .UPDATE... UPDATED THE FORECAST FOR THE EXPIRATION OF THE HIGH WIND WARNING. && .DISCUSSION... THE PRESSURE GRADIENT HAS BEEN DIMINISHING AND IT IS SHOWING IN THE GDP OBS. HAVE ALLOWED THE HIGH WIND WARNING TO EXPIRE...AND HAVE UPDATED ALL RELEVANT PRODUCTS. OTHERWISE THE ONGOING FORECAST LOOKS GOOD FOR NOW. HENNIG && .PREV DISCUSSION... /ISSUED 550 AM CST FRI DEC 5 2008/ DISCUSSION... SEE 12Z AVIATION DISCUSSION BELOW. AVIATION... SURFACE HIGH PRESSURE IS WELL ESTABLISHED ACROSS ALL TERMINALS THIS MORNING. NORTHEAST WINDS WILL CONTINUE THROUGH THE MORNING HOURS WITH HIGH PRESSURE CENTERED EAST OF THE REGION. A TRANSITION TO SOUTH AND SOUTHWEST WINDS WILL TAKE PLACE THIS AFTERNOON AS A SURFACE TROUGH BECOMES ESTABLISHED OVER THE PLAINS OF EASTERN NEW MEXICO AND WEST TEXAS. MID AND HIGH LEVEL CLOUDS WILL ALSO CONTINUE THROUGH THE CURRENT TAF FORECAST PERIOD. PREV DISCUSSION... /ISSUED 500 AM CST FRI DEC 5 2008/ DISCUSSION... EARLY MORNING SURFACE ANALYSIS CONTINUING TO DEPICT A WELL DEVELOPED SURFACE RIDGE EXTENDING INTO WEST TEXAS AND SOUTHEAST NM FROM A PARENT HIGH LOCATED ACROSS NORTH-CENTRAL OK. PRESSURE GRADIENT IN ASSOCIATION WITH FEATURE HAS KEPT A STEADY NORTHEASTERLY WIND THIS MORNING...ULTIMATELY CREATING HIGH WIND WARNING CONDITIONS ACROSS GUADALUPE PASS. LATEST OBS FROM KGDP INDICATE WINDS BLOWING JUST ABOVE WARNING CRITERIA AND BASED ON WIND FORECASTS FROM BOTH THE WRF AND RUC...FAVORABLE NORTHEASTERLY TRAJECTORY WILL CONTINUE THROUGH THE MID MORNING. BASED ON THIS...HAVE DECIDED TO EXTEND THE WARNING THROUGH 15Z...AFTER WHICH WINDS WILL QUICKLY DECEASE AS THE SURFACE FLOW BEGINS TO VEER MORE SOUTHEASTERLY. AFOREMENTIONED RIDGE AXIS REMAINING IN PLACE ACROSS THE REGION TODAY ENSURING ANOTHER DAY OF WELL BELOW NORMAL TEMPS. CURRENT CONDITIONS UPSTREAM SHOW LOW TO MID TEEMS ACROSS NORTHEASTERN KS THIS MORNING...AN INDICATION OF JUST HOW COOL THE AIRMASS IS. WITH THIS IN MIND...HAVE DECIDED TO KEEP TEMPS IN THE LOW TO MID 40S ACROSS MUCH OF THE PERMIAN BASIN TODAY...AS REINFORCED COLD AIR WILL CONTINUE TO SETTLE INTO THE AREA AS SIGNALED BY COOLER H85 TEMPS ALOFT. WITH HIGHS YESTERDAY ONLY CLIMBING INTO THE MID TO UPPER 40S ACROSS MUCH OF THE REGION...FEEL BASING THE CURRENT FORECAST ON PERSISTENCE IS THE WAY TO GO. ALOFT...A HIGHLY SHEARED POSITIVELY TILTED TROUGH WILL PASS OVERHEAD TODAY...YIELDING NOTHING MORE THAN ENHANCED CLOUDINESS ALOFT BEFORE GRADUALLY CLEARING LATE THIS AFTERNOON AND EVENING FROM NORTHWEST TO SOUTHEAST. OVERNIGHT TONIGHT...A SURFACE PRESSURE TROUGH ORIGINATING FROM THE SOUTHERN ROCKIES WILL BEGIN TO WORK ITS WAY EASTWARD...WITH CONTINUATION ACROSS THE REGION THROUGH TOMORROW AFTERNOON. BEHIND THE FEATURE...LOW-LEVEL FLOW WILL BECOME MORE NORTHWESTERLY AS THE AFTERNOON PROGRESSES...SUGGESTING SOME DOWNSLOPE COMPRESSIONAL WARMING POTENTIAL ACROSS PORTIONS OF THE AREA. THIS IN COMBINATION WITH WARMING TEMPS ALOFT WILL SUPPORT NEAR NORMAL TEMPS ACROSS MUCH OF THE REGION TOMORROW...WITH LOW TO MID 60S LIKELY RETURNING. PERIOD OF TRANSITION EXPECTED BY SUNDAY AS A STUBBORN UPPER LOW OFF THE CA COAST BEGINS TO WORK EAST INTO THE DESERT SW/NORTHERN MEX. NORTHWESTERLY MID-LEVEL FLOW WILL GRADUALLY BECOME MORE ZONAL WITH TIME IN ADVANCE OF THIS FEATURE...WITH EMBEDDED SHORTWAVES EXPECTED TO APPROACH WEST TX/SE NM BEGINNING SUN AFTERNOON. INCREASING WESTERLY FLOW ALOFT WILL LEAD TO ENHANCED LEESIDE TROUGHING...WITH TROUGH AXIS EXPECTED TO EXTEND SOUTHWARD ACROSS THE SOUTHEAST NM PLAINS AND WEST TX MOUNTAINS. STRONG WARM AIR ADVECTION EXPECTED ACROSS THE REGION WITH RISING H85 TEMPS THROUGH THE AFTERNOON. FAVORABLE MIXING ALSO ANTICIPATED AS LOW-LEVEL LAPSE RATES BECOME NEARLY DRY ADIABATIC. ONLY CAVEAT WITH INCREASING TEMPS SIGNIFICANTLY WITH THIS MORNING/S UPDATE IS THE EXPECTATIONS OF INCREASING MID AND HIGH LEVEL CLOUDS. IN ANY EVENT...FORECASTED H85 TEMPS SUPPORT LOW TO MID 70S ACROSS MUCH OF THE REGION...HOWEVER WITH CONCERNS REGARDING CLOUDS...HAVE ATTEMPTED TO PLAY IT SAFE AND ONLY RAISE TEMPS A FEW DEGREES FOR NOW PENDING LATER MODEL RUNS. UNSETTLED WEATHER CONTINUING INTO THE EARLY WORK WEEK AS LEESIDE TROUGH/SFC LOW EXITS THE SOUTHERN ROCKIES AND SETTLES INTO THE CENTRAL TX PANHANDLE BY 00Z TUE. ACROSS THE MID-LEVELS...AN UPPER TROUGH IS EXPECTED TO SWING INTO THE REGION AS WELL...WITH THE ECMWF BEING THE MOST BULLISH OF MID-RANGE GUIDANCE. MODELS IN RELATIVELY GOOD AGREEMENT THAT A WELL DEFINED DRYLINE WILL SUPERSEDE THE LOW...HOWEVER FEATURE IS EXPECTED TO GRADUALLY MOVE EASTWARD THROUGHOUT THE DAY AS THE LOW SINKS SOUTHWARD TRAPPING THE BEST RETURN FLOW MOISTURE WELL OFF TO THE EAST OF THE CWA. DESPITE THIS...MODELS DO DEVELOP PRECIP ACROSS THE REGION AS AN UPPER SPEED MAX MOVES ACROSS THE REGION ALONG WITH APPRECIABLE SHORTWAVE ENERGY. HAVE RAISED POPS TO JUST UNDER MENTIONABLE LIMITS FOR NOW BASED ON COLLABORATION WITH ADJACENT OFFICES WHILE AWAITING FOR RUN TO RUN MODEL MODEL CONTINUITY. STRONG COLD FRONT EXPECTED ACROSS THE AREA EARLY TUESDAY MORNING WITH CONTINUED ACCELERATION TO THE SOUTH THROUGH THE DAY. COLD HIGH PRESSURE BUILDING IN BEHIND THE FRONT WILL LEAD TO COOLER TEMPS HOWEVER TEMPS WILL LIKELY REBOUND ON WED BEFORE ANOTHER REINFORCING SHOT OF COLD AIR ARRIVES ON THU. GENERALLY USED A GFS/ECMWF BLEND FOR THE EXTENDED AS MINOR DIFFERENCES AT THE START OF THE PERIOD IRONED THEMSELVES OUT AS THE FORECAST PERIOD ADVANCED. && .PRELIMINARY POINT TEMPS/POPS... BIG SPRING TX 44 29 61 34 / 0 0 0 0 CARLSBAD NM 49 31 67 33 / 0 0 0 0 DRYDEN TX 49 35 67 41 / 0 0 0 0 FORT STOCKTON TX 50 35 70 41 / 0 0 0 0 GUADALUPE PASS TX 47 34 60 39 / 0 0 0 0 HOBBS NM 47 30 65 33 / 0 0 0 0 MARFA TX 51 24 65 28 / 0 0 0 0 MIDLAND INTL AIRPORT TX 45 30 63 35 / 0 0 0 0 ODESSA TX 45 30 63 35 / 0 0 0 0 WINK TX 49 31 70 34 / 0 0 0 0 && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...NONE. && $$ 10/99 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 550 AM CST FRI DEC 5 2008 .DISCUSSION... SEE 12Z AVIATION DISCUSSION BELOW. && .AVIATION... SURFACE HIGH PRESSURE IS WELL ESTABLISHED ACROSS ALL TERMINALS THIS MORNING. NORTHEAST WINDS WILL CONTINUE THROUGH THE MORNING HOURS WITH HIGH PRESSURE CENTERED EAST OF THE REGION. A TRANSITION TO SOUTH AND SOUTHWEST WINDS WILL TAKE PLACE THIS AFTERNOON AS A SURFACE TROUGH BECOMES ESTABLISHED OVER THE PLAINS OF EASTERN NEW MEXICO AND WEST TEXAS. MID AND HIGH LEVEL CLOUDS WILL ALSO CONTINUE THROUGH THE CURRENT TAF FORECAST PERIOD. && .PREV DISCUSSION... /ISSUED 500 AM CST FRI DEC 5 2008/ DISCUSSION... EARLY MORNING SURFACE ANALYSIS CONTINUING TO DEPICT A WELL DEVELOPED SURFACE RIDGE EXTENDING INTO WEST TEXAS AND SOUTHEAST NM FROM A PARENT HIGH LOCATED ACROSS NORTH-CENTRAL OK. PRESSURE GRADIENT IN ASSOCIATION WITH FEATURE HAS KEPT A STEADY NORTHEASTERLY WIND THIS MORNING...ULTIMATELY CREATING HIGH WIND WARNING CONDITIONS ACROSS GUADALUPE PASS. LATEST OBS FROM KGDP INDICATE WINDS BLOWING JUST ABOVE WARNING CRITERIA AND BASED ON WIND FORECASTS FROM BOTH THE WRF AND RUC...FAVORABLE NORTHEASTERLY TRAJECTORY WILL CONTINUE THROUGH THE MID MORNING. BASED ON THIS...HAVE DECIDED TO EXTEND THE WARNING THROUGH 15Z...AFTER WHICH WINDS WILL QUICKLY DECEASE AS THE SURFACE FLOW BEGINS TO VEER MORE SOUTHEASTERLY. AFOREMENTIONED RIDGE AXIS REMAINING IN PLACE ACROSS THE REGION TODAY ENSURING ANOTHER DAY OF WELL BELOW NORMAL TEMPS. CURRENT CONDITIONS UPSTREAM SHOW LOW TO MID TEEMS ACROSS NORTHEASTERN KS THIS MORNING...AN INDICATION OF JUST HOW COOL THE AIRMASS IS. WITH THIS IN MIND...HAVE DECIDED TO KEEP TEMPS IN THE LOW TO MID 40S ACROSS MUCH OF THE PERMIAN BASIN TODAY...AS REINFORCED COLD AIR WILL CONTINUE TO SETTLE INTO THE AREA AS SIGNALED BY COOLER H85 TEMPS ALOFT. WITH HIGHS YESTERDAY ONLY CLIMBING INTO THE MID TO UPPER 40S ACROSS MUCH OF THE REGION...FEEL BASING THE CURRENT FORECAST ON PERSISTENCE IS THE WAY TO GO. ALOFT...A HIGHLY SHEARED POSITIVELY TILTED TROUGH WILL PASS OVERHEAD TODAY...YIELDING NOTHING MORE THAN ENHANCED CLOUDINESS ALOFT BEFORE GRADUALLY CLEARING LATE THIS AFTERNOON AND EVENING FROM NORTHWEST TO SOUTHEAST. OVERNIGHT TONIGHT...A SURFACE PRESSURE TROUGH ORIGINATING FROM THE SOUTHERN ROCKIES WILL BEGIN TO WORK ITS WAY EASTWARD...WITH CONTINUATION ACROSS THE REGION THROUGH TOMORROW AFTERNOON. BEHIND THE FEATURE...LOW-LEVEL FLOW WILL BECOME MORE NORTHWESTERLY AS THE AFTERNOON PROGRESSES...SUGGESTING SOME DOWNSLOPE COMPRESSIONAL WARMING POTENTIAL ACROSS PORTIONS OF THE AREA. THIS IN COMBINATION WITH WARMING TEMPS ALOFT WILL SUPPORT NEAR NORMAL TEMPS ACROSS MUCH OF THE REGION TOMORROW...WITH LOW TO MID 60S LIKELY RETURNING. PERIOD OF TRANSITION EXPECTED BY SUNDAY AS A STUBBORN UPPER LOW OFF THE CA COAST BEGINS TO WORK EAST INTO THE DESERT SW/NORTHERN MEX. NORTHWESTERLY MID-LEVEL FLOW WILL GRADUALLY BECOME MORE ZONAL WITH TIME IN ADVANCE OF THIS FEATURE...WITH EMBEDDED SHORTWAVES EXPECTED TO APPROACH WEST TX/SE NM BEGINNING SUN AFTERNOON. INCREASING WESTERLY FLOW ALOFT WILL LEAD TO ENHANCED LEESIDE TROUGHING...WITH TROUGH AXIS EXPECTED TO EXTEND SOUTHWARD ACROSS THE SOUTHEAST NM PLAINS AND WEST TX MOUNTAINS. STRONG WARM AIR ADVECTION EXPECTED ACROSS THE REGION WITH RISING H85 TEMPS THROUGH THE AFTERNOON. FAVORABLE MIXING ALSO ANTICIPATED AS LOW-LEVEL LAPSE RATES BECOME NEARLY DRY ADIABATIC. ONLY CAVEAT WITH INCREASING TEMPS SIGNIFICANTLY WITH THIS MORNING/S UPDATE IS THE EXPECTATIONS OF INCREASING MID AND HIGH LEVEL CLOUDS. IN ANY EVENT...FORECASTED H85 TEMPS SUPPORT LOW TO MID 70S ACROSS MUCH OF THE REGION...HOWEVER WITH CONCERNS REGARDING CLOUDS...HAVE ATTEMPTED TO PLAY IT SAFE AND ONLY RAISE TEMPS A FEW DEGREES FOR NOW PENDING LATER MODEL RUNS. UNSETTLED WEATHER CONTINUING INTO THE EARLY WORK WEEK AS LEESIDE TROUGH/SFC LOW EXITS THE SOUTHERN ROCKIES AND SETTLES INTO THE CENTRAL TX PANHANDLE BY 00Z TUE. ACROSS THE MID-LEVELS...AN UPPER TROUGH IS EXPECTED TO SWING INTO THE REGION AS WELL...WITH THE ECMWF BEING THE MOST BULLISH OF MID-RANGE GUIDANCE. MODELS IN RELATIVELY GOOD AGREEMENT THAT A WELL DEFINED DRYLINE WILL SUPERSEDE THE LOW...HOWEVER FEATURE IS EXPECTED TO GRADUALLY MOVE EASTWARD THROUGHOUT THE DAY AS THE LOW SINKS SOUTHWARD TRAPPING THE BEST RETURN FLOW MOISTURE WELL OFF TO THE EAST OF THE CWA. DESPITE THIS...MODELS DO DEVELOP PRECIP ACROSS THE REGION AS AN UPPER SPEED MAX MOVES ACROSS THE REGION ALONG WITH APPRECIABLE SHORTWAVE ENERGY. HAVE RAISED POPS TO JUST UNDER MENTIONABLE LIMITS FOR NOW BASED ON COLLABORATION WITH ADJACENT OFFICES WHILE AWAITING FOR RUN TO RUN MODEL MODEL CONTINUITY. STRONG COLD FRONT EXPECTED ACROSS THE AREA EARLY TUESDAY MORNING WITH CONTINUED ACCELERATION TO THE SOUTH THROUGH THE DAY. COLD HIGH PRESSURE BUILDING IN BEHIND THE FRONT WILL LEAD TO COOLER TEMPS HOWEVER TEMPS WILL LIKELY REBOUND ON WED BEFORE ANOTHER REINFORCING SHOT OF COLD AIR ARRIVES ON THU. GENERALLY USED A GFS/ECMWF BLEND FOR THE EXTENDED AS MINOR DIFFERENCES AT THE START OF THE PERIOD IRONED THEMSELVES OUT AS THE FORECAST PERIOD ADVANCED. && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...HIGH WIND WARNING UNTIL 8 AM MST THIS MORNING FOR THE FOLLOWING ZONES... GUADALUPE MOUNTAINS. && $$ 06 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 500 AM CST FRI DEC 5 2008 .DISCUSSION... EARLY MORNING SURFACE ANALYSIS CONTINUING TO DEPICT A WELL DEVELOPED SURFACE RIDGE EXTENDING INTO WEST TEXAS AND SOUTHEAST NM FROM A PARENT HIGH LOCATED ACROSS NORTH-CENTRAL OK. PRESSURE GRADIENT IN ASSOCIATION WITH FEATURE HAS KEPT A STEADY NORTHEASTERLY WIND THIS MORNING...ULTIMATELY CREATING HIGH WIND WARNING CONDITIONS ACROSS GUADALUPE PASS. LATEST OBS FROM KGDP INDICATE WINDS BLOWING JUST ABOVE WARNING CRITERIA AND BASED ON WIND FORECASTS FROM BOTH THE WRF AND RUC...FAVORABLE NORTHEASTERLY TRAJECTORY WILL CONTINUE THROUGH THE MID MORNING. BASED ON THIS...HAVE DECIDED TO EXTEND THE WARNING THROUGH 15Z...AFTER WHICH WINDS WILL QUICKLY DECEASE AS THE SURFACE FLOW BEGINS TO VEER MORE SOUTHEASTERLY. AFOREMENTIONED RIDGE AXIS REMAINING IN PLACE ACROSS THE REGION TODAY ENSURING ANOTHER DAY OF WELL BELOW NORMAL TEMPS. CURRENT CONDITIONS UPSTREAM SHOW LOW TO MID TEEMS ACROSS NORTHEASTERN KS THIS MORNING...AN INDICATION OF JUST HOW COOL THE AIRMASS IS. WITH THIS IN MIND...HAVE DECIDED TO KEEP TEMPS IN THE LOW TO MID 40S ACROSS MUCH OF THE PERMIAN BASIN TODAY...AS REINFORCED COLD AIR WILL CONTINUE TO SETTLE INTO THE AREA AS SIGNALED BY COOLER H85 TEMPS ALOFT. WITH HIGHS YESTERDAY ONLY CLIMBING INTO THE MID TO UPPER 40S ACROSS MUCH OF THE REGION...FEEL BASING THE CURRENT FORECAST ON PERSISTENCE IS THE WAY TO GO. ALOFT...A HIGHLY SHEARED POSITIVELY TILTED TROUGH WILL PASS OVERHEAD TODAY...YIELDING NOTHING MORE THAN ENHANCED CLOUDINESS ALOFT BEFORE GRADUALLY CLEARING LATE THIS AFTERNOON AND EVENING FROM NORTHWEST TO SOUTHEAST. OVERNIGHT TONIGHT...A SURFACE PRESSURE TROUGH ORIGINATING FROM THE SOUTHERN ROCKIES WILL BEGIN TO WORK ITS WAY EASTWARD...WITH CONTINUATION ACROSS THE REGION THROUGH TOMORROW AFTERNOON. BEHIND THE FEATURE...LOW-LEVEL FLOW WILL BECOME MORE NORTHWESTERLY AS THE AFTERNOON PROGRESSES...SUGGESTING SOME DOWNSLOPE COMPRESSIONAL WARMING POTENTIAL ACROSS PORTIONS OF THE AREA. THIS IN COMBINATION WITH WARMING TEMPS ALOFT WILL SUPPORT NEAR NORMAL TEMPS ACROSS MUCH OF THE REGION TOMORROW...WITH LOW TO MID 60S LIKELY RETURNING. PERIOD OF TRANSITION EXPECTED BY SUNDAY AS A STUBBORN UPPER LOW OFF THE CA COAST BEGINS TO WORK EAST INTO THE DESERT SW/NORTHERN MEX. NORTHWESTERLY MID-LEVEL FLOW WILL GRADUALLY BECOME MORE ZONAL WITH TIME IN ADVANCE OF THIS FEATURE...WITH EMBEDDED SHORTWAVES EXPECTED TO APPROACH WEST TX/SE NM BEGINNING SUN AFTERNOON. INCREASING WESTERLY FLOW ALOFT WILL LEAD TO ENHANCED LEESIDE TROUGHING...WITH TROUGH AXIS EXPECTED TO EXTEND SOUTHWARD ACROSS THE SOUTHEAST NM PLAINS AND WEST TX MOUNTAINS. STRONG WARM AIR ADVECTION EXPECTED ACROSS THE REGION WITH RISING H85 TEMPS THROUGH THE AFTERNOON. FAVORABLE MIXING ALSO ANTICIPATED AS LOW-LEVEL LAPSE RATES BECOME NEARLY DRY ADIABATIC. ONLY CAVEAT WITH INCREASING TEMPS SIGNIFICANTLY WITH THIS MORNING/S UDPATE IS THE EXPECTATIONS OF INCREASING MID AND HIGH LEVEL CLOUDS. IN ANY EVENT...FORECASTED H85 TEMPS SUPPORT LOW TO MID 70S ACROSS MUCH OF THE REGION...HOWEVER WITH CONCERNS REGARDING CLOUDS...HAVE ATTEMPTED TO PLAY IT SAFE AND ONLY RAISE TEMPS A FEW DEGREES FOR NOW PENDING LATER MODEL RUNS. UNSETTLED WEATHER CONTINUING INTO THE EARLY WORK WEEK AS LEESIDE TROUGH/SFC LOW EXITS THE SOUTHERN ROCKIES AND SETTLES INTO THE CENTRAL TX PANHANDLE BY 00Z TUE. ACROSS THE MID-LEVELS...AN UPPER TROUGH IS EXPECTED TO SWING INTO THE REGION AS WELL...WITH THE ECMWF BEING THE MOST BULLISH OF MID-RANGE GUIDANCE. MODELS IN RELATIVELY GOOD AGREEMENT THAT A WELL DEFINED DRYLINE WILL SUPERSEDE THE LOW...HOWEVER FEATURE IS EXPECTED TO GRADUALLY MOVE EASTWARD THROUGHOUT THE DAY AS THE LOW SINKS SOUTHWARD TRAPPING THE BEST RETURN FLOW MOISTURE WELL OFF TO THE EAST OF THE CWA. DESPITE THIS...MODELS DO DEVELOP PRECIP ACROSS THE REGION AS AN UPPER SPEED MAX MOVES ACROSS THE REGION ALONG WITH APPRECIABLE SHORTWAVE ENERGY. HAVE RAISED POPS TO JUST UNDER MENTIONABLE LIMITS FOR NOW BASED ON COLLABORATION WITH ADJACENT OFFICES WHILE AWAITING FOR RUN TO RUN MODEL MODEL CONTINUITY. STRONG COLD FRONT EXPECTED ACROSS THE AREA EARLY TUESDAY MORNING WITH CONTINUED ACCELERATION TO THE SOUTH THROUGH THE DAY. COLD HIGH PRESSURE BUILDING IN BEHIND THE FRONT WILL LEAD TO COOLER TEMPS HOWEVER TEMPS WILL LIKELY REBOUND ON WED BEFORE ANOTHER REINFORCING SHOT OF COLD AIR ARRIVES ON THU. GENERALLY USED A GFS/ECMWF BLEND FOR THE EXTENDED AS MINOR DIFFERENCES AT THE START OF THE PERIOD IRONED THEMSELVES OUT AS THE FORECAST PERIOD ADVANCED. && .PRELIMINARY POINT TEMPS/POPS... BIG SPRING TX 44 29 61 34 / 0 0 0 0 CARLSBAD NM 49 31 67 33 / 0 0 0 0 DRYDEN TX 49 35 67 41 / 0 0 0 0 FORT STOCKTON TX 50 35 70 41 / 0 0 0 0 GUADALUPE PASS TX 47 34 60 39 / 0 0 0 0 HOBBS NM 47 30 65 33 / 0 0 0 0 MARFA TX 51 24 65 28 / 0 0 0 0 MIDLAND INTL AIRPORT TX 45 30 63 35 / 0 0 0 0 ODESSA TX 45 30 63 35 / 0 0 0 0 WINK TX 49 31 70 34 / 0 0 0 0 && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...HIGH WIND WARNING UNTIL 8 AM MST THIS MORNING FOR THE FOLLOWING ZONES... GUADALUPE MOUNTAINS. && $$ 32 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1011 PM EST FRI DEC 5 2008 .SYNOPSIS... COLD HIGH PRESSURE WILL BE CENTERED OVER THE MID ATLANTIC STATES TONIGHT. A FAST MOVING ALBERTA CLIPPER WILL MOVE ACROSS THE OHIO VALLEY SATURDAY PASSING NORTH OF THE AREA SATURDAY NIGHT. MOUNTAIN SNOW SHOWERS AND FLURRIES ARE LIKELY SATURDAY NIGHT INTO SUNDAY ALONG WITH BLUSTERY NORTHWEST WINDS. && .NEAR TERM /THROUGH SATURDAY/... THE LATEST 12KM NAM...AND TO AN EXTENT THE RUC13 IS DOING A GOOD JOB SHOWING THE CLOUDINESS OVER THE NC FOOTHILLS. NAM MODEL SOUNDINGS SUGGEST A SHALLOW LAYER OF THIS CLOUD DECK TO SHIFT NORTH AND EAST INTO THE OUR SRN CWA THROUGH DAWN. HAVE MADE ADJUSTMENTS TO THE GRIDS TO ACCOUNT FOR THIS. OTHERWISE...LOOKING AT EXCELLENT RADIATIONAL COOLING CONDITIONS TONIGHT AS HIGH PRESSURE SETTLES OVER THE AREA. MODELS DO SHOW SOME WARM AIR ADVECTING IN ALOFT AFTER MIDNIGHT. THIS MAY KEEP SOUTHWESTERN VIRGINIA RIDGES (BLF) WARMER THAN THE REST OF THE AREA OVERNIGHT. DESPITE CALLING THE RIDGES WARMER...STILL LOOKING AT A COLD NIGHT WITH TEMPERATURES 10-20F ACROSS THE MOUNTAINS TO LOWER 20S EAST AND ALONG SW VA WESTERN RIDGES. THE 12KM NAM IS DEPICTING WARM AIR ADVECTION CONTINUES INTO THE DAY SATURDAY...AHEAD OF A CLIPPER CROSSING OVER THE GREAT LAKES. MOISTURE TRANSPORT INCREASING THROUGH THE DAY ON SOUTHWESTERLY FLOW. THIS WILL BRING AN INCREASE IN CLOUDS ACROSS THE AREA THROUGH THE DAY. ATMOSPHERE REMAINING COLD WITH 850 MB TEMPERATURES -4C TO -7C. IF PRECIP DOES FALL SATURDAY AFTERNOON...IT WILL REMAIN AS SNOW...ALONG AND WEST OF THE BLUE RIDGE AS RELATIVELY WARM SURFACE LAYER WILL BE SHALLOW.. IF CLOUDS INCREASE DURING THE MORNING...INSOLATION WILL BE LIMITED AND A FEW FLAKES COULD BE OBSERVED IN THE PIEDMONT. OF COURSE...THAT IS IF PRECIP FALLS. 12Z NAM BEING ONE OF THE DRIEST MODELS TODAY ONLY HAS GREENBIER AND BATH COUNTY WITH MEASURABLE PRECIP. ON THE OTHER HAND...12Z GFS/CANADIAN/EUROPEAN HAS PRECIP AS FAR EAST AS THE FOOTHILLS. I DO HAVE SOME CONCERNS ABOUT THE START TIME AND MEASURABLE AMOUNTS WITH PARENT LOW SO FAR NORTH AND OVER THE GREAT LAKES. WILL SLOW DOWN POPS JUST A TAD UNTIL THE MID TO LATE AFTERNOON WITH THESE CONCERNS AND THAT THE ATMOSPHERE WILL NEED TIME TO SATURATE AGAIN. WILL MAINTAIN CHANCE POPS ACROSS THE WEST WITH SLIGHT CHANCE IN THE EAST. NEVERTHELESS...ACCUMULATIONS WILL BE LIGHT DURING THE DAY. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... PASSAGE OF ALBERTA CLIPPER WILL BRING PERIOD OF BLUSTERY NORTHWEST WINDS TO THE AREA SATURDAY NIGHT AND SUNDAY WITH A REINFORCING SHOT OF ARCTIC AIR...850 TEMPS DIPPING TO M12-M15 DEG C RANGE SUNDAY MORNING. DYNAMIC LIFT ASSOCIATED WITH THE SYSTEM SUGGESTS ENTIRE CWA COULD SEE A -SHSN WITH ITS PASSAGE SATURDAY NIGHT...A DUSTING EVEN POSSIBLE EAST OF THE MTNS IF FORCING CAN GENERATE SUSTAINABLE PERIOD OF CRYSTAL GROWTH THERE. OF COURSE THE HIGHEST POPS WILL AGAIN BE MAINLY CONFINED TO THE MOUNTAINS WHERE UPSLOPE MTN PEAKS TO RECEIVE AN INCH OR TWO. TRAJECTORY FORECAST FOR EARLY SUNDAY MORNING SUGGEST FETCH OFF OF LAKE MICHIGAN TO INTERSECT MOUNTAINS OVER CENTRAL WVA. THIS IS NOT A GREAT FETCH FOR OUR FORECAST AREA...SUGGESTING THE DEEPER MOISTURE WILL REMAIN NORTH OF THE CWA. NEVER THE LESS...IN SPITE OF THE SHALLOWNESS OF THE MOISTURE...LESS THAN 5KFT IN DEPTH...ARCTIC AIRMASS WITH CLOUD TOP TEMPS NEAR M15 DEG C WILL PROVIDE SUFFICIENT CRYSTAL GROWTH FOR PERSISTENT SNOW SHOWERS AND FLURRIES LATE SATURDAY NIGHT INTO SUNDAY FOR THE MOUNTAINS. ATTM...LOOKS LIKE AN ADVISORY LEVEL EVENT FOR HIGHER SPOTS OF GREENBRIER/MERCER...WITH MUCH OF THE SNOW FALLING IN A SMALL TIME PERIOD WHEN THE MOST FAVORABLE CONDITIONS COMBINE FROM 6Z-15Z SUN. FIVE TO SIX INCHES OF SNOW COULD FALL IN WESTERN GREENBRIER BY NOON SUNDAY...AS SNW SHWS SHOULD PERSIST UNTIL LATER SUNDAY. AS USUAL THE LWR ELEVATIONS OF GREENBRIER...LEWISBURG PROPER...WILL GET MUCH LESS. UPSLOPE SNOW DOESNT GET GOING UNTIL CLOSER TO SUNDAY 12Z NW NC...WHERE 1-3" COULD FALL...MOST OF COURSE ALONG THE SKI RESORTS. COLD HIGH PRESSURE WILL SETTLE OVER THE AREA SUNDAY NIGHT...1030 MB...PASSING OVERHEAD AROUND 06 UTC...THEN TO ALONG THE MID ATLANTIC COAST BY 18 UTC. CLEAR SKIES AND DIMINISHING WINDS SHOULD PROMOTE COLD SURFACE TEMPS SUNDAY NIGHT. WARM AIR ADVECTION ON THE BACK SIDE OF THE HIGH WILL USHER IN INCREASING CLOUDS MONDAY AHEAD OF THE NEXT SYSTEM THAT WILL IMPACT THE REGION. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... GUIDANCE HAS COME INTO BETTER AGREEMENT ON MAINTAINING TWO SEPARATE SHORTWAVE TROUGHS AS A MEAN LONGWAVE TROUGH DEVELOPS OVER THE PLAINS AND SOUTHERN ROCKIES ON DAY 3...BEFORE PROGRESSING THROUGH THE REMAINDER OF THE CONUS BY DAYS 6/7. HIGH PRESSURE WILL BE OFFSHORE BY MONDAY NIGHT WITH STRONG WARM AIR ADVECTION DEVELOPING. BY TUESDAY NIGHT THE FORECAST AREA WILL BE WELL INTO THE WARM SECTOR SO THERE MAY NOT BE MUCH OF A DROP IN OVERNIGHT TEMPERATURES. HAVE SLOWED DOWN THE TIMING OF THE FRONT...BUT EVEN WITH FRONT NOT COMING THROUGH UNTIL LATER ON WEDNESDAY...TEMPERATURES MAY ONLY RISE A FEW DEGREES WITH ALL THE PRECIPITATION AND CLOUD COVER. NOT MUCH CHANGE TO HPC GUIDANCE FOR DAYS 6 AND 7 EXCEPT TO CONFINE SHOWERS TO THE MOUNTAINS. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... HIGH PRESSURE WILL SLOWLY MOVE OVER THE AREA THROUGH THE PERIOD...KEEPING VFR CONDITIONS IN PLACE. LIGHT WINDS ARE EXPECTED OVERNIGHT AS THE HIGH PRESSURE BUILDS IN. SATURDAY...THERE WILL BE INCREASING HIGH CLOUDINESS IN THE MORNING...AND THEN LOWERING CIGS HEADING INTO THE AFTERNOON AS A CLIPPER MOVES RAPIDLY SEWD INTO THE TN VALLEY BY 00Z SUNDAY. THIS WILL LIKELY SPREAD SNOW INTO THE BLF AND LWB AREAS MAINLY AFTER THIS TAF PERIOD. CIGS/VSBYS SHOULD REMAIN VFR UNTIL THEN...WITH CIGS DROPPING TO LOW END VFR. AFTER 00Z SUNDAY...SNOW MAY BRING MVFR TO OCNL IFR CONDITIONS TO BLF AND LWB...AND THESE FLIGHT CONDITIONS WILL CONTINUE THROUGH SUNDAY MORNING WITH UPSLOPE SNOW SHOWERS AFTER THE CLIPPER PASSES BY. ROA...LYH AND DAN WILL BE VFR INTO SUNDAY...BUT WITH GUSTY NORTHWEST WINDS...ARRIVING LATE SAT NIGHT. VFR WEATHER IS EXPECTED SUNDAY NIGHT THROUGH MONDAY NIGHT AS ANOTHER COLD HIGH PRESSURE BUILDS INTO THE AREA. ANOTHER COLD FRONT WILL APPROACH THE REGION TUESDAY...BRINGING DETERIORATING CONDITIONS IN RAIN AND A GOOD CHC OF MVFR...POSSIBLY IFR CIGS AND VSBYS BY THE END OF THE DAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PM NEAR TERM...RCS/WP SHORT TERM...PM LONG TERM...AMS AVIATION...RCS/WP va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 357 AM CST FRI DEC 5 2008 .DISCUSSION...FORECAST FOCUS IS ON SNOW FOR TONIGHT INTO SATURDAY MORNING...THEN SYSTEM FOR SUNDAY NIGHT THROUGH MONDAY NIGHT. TODAY- COLD 850 MILLIBAR POCKET WILL GET WHISKED EAST AS WARM AIR ADVECTION GETS GOING. QUITE A BIT OF STRATOCU AROUND FROM WESTERN WI EXTENDING INTO IA AND MN WITH THE CIRRUS SHIELD SPREADING SEWD FROM CANADA. 925 MB TEMPERATURES SUPPORT THE LOWER 20S WE HAVE GOING IN THE GRIDS SO WONT CHANGE TOO MUCH THERE. SO EVEN THOUGH WAA KICKING IN...INCREASE IN CLOUDS...WINDS AND THE COLD START WILL PRETTY MUCH KEEP THE CHILL GOING ALL DAY. TONIGHT- RAPID ISENTROPIC MOISTENING ON THE 280-285K ISENTROPIC PLOTS THIS EVENING AS DECENT UPGLIDE LEADS TO SATURATION WITHIN THE WAA REGIME AHEAD OF APPROACHING TROUGH. THIS LOOKS TO BE A QUICK HITTER WITH 700-300MB Q VECTOR CONVERGENCE SHOWING A PEAK IN THE L-M20S AROUND 6Z WITH MUCH OF THE LIFT AND ISENTROPIC ADIABATIC OMEGA EXITING SHORTLY AFTER 12Z SATURDAY. NOT A REAL STRONG CROSS HAIRS SIGNATURE. MIXING RATIOS ARE AROUND 1.5 G/KG IN THE 700-725MB LAYER. RATIOS EXPECTED TO BE 15:1. GIVEN QPF AMOUNTS AROUND 0.15 THE GOING 2-3 INCH FORECAST LOOKS LIKE A TOUGH TWEEK. WILL MENTION SOME BLOWING SNOW IN THE HWO AS BUFKIT WINDS/PROGGD SFC GRADIENT SHOW PRETTY BRISK CONDITIONS DURING TIME OF PEAK SNOWFALL AND COMBINED WITH HIGHER RATIOS/LOWER WATER CONTENT SNOW...COULD BE SOME ISSUES WITH THAT. SATURDAY- SURFACE-850 FRONT WILL BE EXITING EARLY WITH MID LEVEL TROUGH AXIS ROTATING ACROSS MIDDAY. WILL HAVE HIGHEST POPS IN THE EAST. RETURN TO COLD AIR ADVECTION DURING THE DAY WITH 700 MILLIBAR DRYING AND SUBSIDENCE ESPECIALLY AFTER PASSAGE OF MID LEVEL TROUGH AXIS. FAIRLY STEEP LOW LEVEL LAPSE RATES MAY BE CONDUCIVE TO A FEW SNOW SHOWERS DURING THE AFTERNOON WITH WINDS CRANKING UP AS WELL. GFS/NAM AND CRAS SUGGESTING LIGHT QPF TIED TO THE MID LEVEL VORT. SUNDAY- QUIET AND CHILLY AS HIGH PRESSURE RIDGE SLIDES ACROSS THE STATE. SUNDAY NIGHT INTO MONDAY- SNOW EXPECTED TO REDEVELOP SUNDAY EVENING AS RENEWED ISENTROPIC FORCING INTERACTS WITH RIGHT REAR QUADRANT OF UPPER LEVEL JET STREAM. RAPID SATURATION AGAIN NOTED ON THE ISENTROPIC SURFACES WITH CRASHING CONDENSATION PRESSURE DEFICITS. 12Z AND 00Z ECMWF HAD QPF MAX TO OUR NORTH HOWEVER THEY HAVE TRENDED A BIT SOUTH MORE INTO THE OUR CWA. MEANWHILE GFS AND NAM HAVE A MORE SOUTHERN PLACEMENT OF QPF ACORSS NORTHERN ILLINOIS. BEST ROUTE FOR NOW IS TO GO WITH CHANCE POPS FOR THIS LEAD WAA EVENT. MONDAY NIGHT AND TUESDAY- 00Z ECMWF DEFINITELY PAINTING A GLOOMIER SCENARIO WITH A STRONGER SOUTHERN WAVE SCOOTING NEWD TOWARDS OHIO VALLEY WHILE GFS HAS MUCH MORE INFLUENCE OF THE NORTHERN STREAM AND A QUICKER MORE PROGRESSIVE LOOK TO THINGS. ECMWF CERTAINLY TAPS MORE MOISTURE AND BRINGS ALMOST 0.50 INCH LIQUID WITH IT/S ASSOCIATED ENERGY. && .AVIATION...LATEST IR IMAGES SHOWING WIDE SWATH OF LOW CLOUDS UPSTREAM OVER MN/IA CAUGHT UNDERNEATH SUBSIDENCE INVERSION. WITH THERMAL TROUGH LINGERING OVER WI THROUGH THE MORNING AND INCREASING WSW LOW LEVEL FLOW...WOULD EXPECT A PERIOD OF BKN-OVC CLOUDS THIS MORNING WITH CEILING HEIGHTS AROUND 3K FEET. LATEST RUC ALSO SHOWING SOME INCREASE IN LOW LEVEL RH THIS MORNING. WOULD EXPC CEILINGS TO INCREASE TO VFR THIS AFTN IN INCREASING LOW LEVEL FLOW AHEAD OF APPROACHING CLIPPER SYSTEM. PERIOD OF SNOW FROM 05Z THROUGH 14Z WILL RESULT IN IFR VSBYS AND MVFR CIGS TONIGHT. && .MARINE...WILL CONTINUE BORDERLINE SMALL CRAFT ADVISORY THIS MORNING AS RELATIVELY WARMER WATERS OF LAKE MICHIGAN WITH SURFACE TEMPS AROUND 4 DEGREES C ALLOWING WINDS TO GUST INTO THE LOWER TO MIDDLE 20S TOWARDS THE OPEN WATERS...AS VERIFIED BY HARRISON CRIB LAST FEW HOURS. TIGHTENING PRESSURE GRADIENT AHEAD OF CANADIAN CLIPPER WILL RESULT IN STRONG LOW LEVEL SOUTHWEST WINDS DEVELOPING OVER THE NEARSHORE WATERS THIS AFTERNOON AND EVENING. STEEP LOW LEVEL LAPSE RATES COULD RESULT IN A BRIEF PERIOD OF GALE FORCE GUSTS MIXING DOWN TO SURFACE THIS EVENING BUT ATTM THINKING THIS WILL BE BRIEF...SO WL CONTINUE SMALL CRAFT ADVISORY THROUGH TONIGHT AND SATURDAY MORNING LEADING UP TO WIND SHIFT ASSOCIATED WITH PASSING SYSTEM. STRONG LOW LEVEL COLD AIR ADVECTION DEVELOPS SATURDAY AFTERNOON WITH A BETTER CHANCE FOR A MORE PROLONGED PERIOD OF GALE FORCE WINDS AND/OR GUSTS DUE TO VERY STEEP LOW LEVEL LAPSE RATES. HENCE CONVERTED SMALL CRAFT ADVISORY THAT WAS IN EFFECT SAT AFTN TO GALE WATCH AND EXTENDED HEADLINE TO 06Z/SUN. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...GALE WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY EVENING FOR LMZ643>646. SMALL CRAFT ADVISORY UNTIL 12 PM CST SATURDAY FOR LMZ643>646. && $$ SHORT/LONG TERM...PAC AVIATION/MARINE...MBK wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 400 AM EST SAT DEC 6 2008 .SHORT TERM... ...WINTER WEATHER TO IMPACT THE REGION TODAY AND TONIGHT... TODAY THROUGH SUNDAY NIGHT RATHER POTENT SHORTWAVE TROUGH AND ASSOCIATED SFC CYCLONE IS PUSHING INTO THE GREAT LAKES REGION. AN AREA ON LIGHT TO MODERATE SNOW IS ONGOING OVER PORTIONS OF IL/IN/WI IN THE WARM CONVEYOR BELT PORTION OF THE SYSTEM...WHERE A 50 KNOT LL JET IS AIDING IN WEAK MOISTURE ADVECTION AND CROSS ISOBARIC FLOW...LENDING TO UPGLIDE. VERY DRY COLUMN AS INDICATED BY ILX AND DVN SOUNDINGS IS ACTING TO LIMIT SNOWFALL SOMEWHAT...SUPPORTING WIDESPREAD VIRGA UNTIL SATURATION IS REACHED. THIS IS EVIDENT IN THE DONUT HOLE SIGNATURES THAT WERE OBSERVED AT DVN/ILX/AND LOT. REGARDLESS...ONCE SATURATION IS REACHED...EXPECTING A PERIOD OF LIGHT TO MODERATE SNOW TO OVERSPREAD THE REGION...SUPPORTING A QUICK BURST OF 1 TO 2 INCHES OF SNOW...WITH 1 INCH AMOUNTS MORE THE NORM. RATHER ROBUST TROPOPAUSE PRESSURE RISES COUPLED WITH STEEP MID LEVEL LAPSE RATES AND DECENT MOISTURE CONVERGENCE WILL CONTINUE TO SO SUPPORT BROAD LIFT THROUGH MUCH OF THE MORNING AND ACROSS THE FA. HAVE FAVORED THE SREF AND GFS WRT QPF GUIDANCE WITH THE CLIPPER SYSTEM...BUT OPTED FOR THE SUPPORT OF THE NAM12 FOR LAKE EFFECT PROCESSES. ALSO UTILIZED THE RUC13 FOR ADDED GUIDANCE. TODAY...CLIPPER SYSTEM WILL QUICKLY LEAVE GENERALLY 1 INCH OF SNOWFALL ACROSS THE MAJORITY OF THE FA. IN ADDITION STAUNCH FLOW/A RATHER TIGHT PRESSURE GRADIENT/STRONG FLOW ALOFT...45 TO 50 KNOTS OF H95 GEOSTROPHIC FLOW/AND LINKED MOMENTUM UNDER CAA WILL SUPPORT GUSTY WESTERLY WINDS. SUSTAINED WINDS OF 15 TO 25 MPH WITH HIGHER GUSTS ARE EXPECTED THROUGH THE EVENING. THIS WILL ALLOW FOR AREAS OF BLOWING AND DRIFTING SNOW...MAKING TRAVEL DIFFICULT IN SOME AREAS. ROBUST CAA WITH H85 T/S DROPPING 5 TO 6C WILL HELP SUPPORT INCREASED INSTABILITY OVER LK MI THIS AFTERNOON. WESTERLY FLOW AT FIRST WILL LIMIT LK SNOW SHOWERS TO MAINLY MI THIS AFTERNOON. LL FLOW WILL CONTINUE TO VEER BEHIND THE COLD FRONT...INCREASING THE FLOW FETCH OVER LK MI...WITH PRECONDITIONED FLOW FROM LAKE SUPERIOR DEVELOPING. A SECONDARY UPPER IMPULSE WILL ACT TO FURTHER INCREASE INVERSION HEIGHTS ALREADY MODIFIED BY LAKE AGGREGATE EFFECTS FROM LK SUPERIOR. THE NET EFFECT WILL BE LAKE INDUCED CAPES OF 500 TO 700 J/KG WITH MAX UPWARD OMEGA IN THE DGZ. THIS WILL FAVOR THE DEVELOPMENT OF SEVERAL INTENSE BANDS OF LK EFFECT SNOW...CONGEALING INTO ONE DOMINATE BAND AS CONVECTIVE INFLUENCES EVENTUALLY OUTWEIGH WIND SHEAR EFFECTS. NAM12 AND RUC 13 PROGS HAVE CONSISTENTLY BEEN SUPPORTING THE PLACEMENT OF THIS BAND OVER EASTERN BERRIEN AND CASS COUNTIES. HIRES WRF SIMULATIONS FURTHER SUPPORT THIS IDEA. SNOWFALL RATES OF 2 TO 4 INCHES PER HOUR ARE WILL BE POSSIBLE WITH AN INTENSE DOMINATE BAND...ESPECIALLY IF THE LL MASS FIELD READJUSTS TO THE MESOSCALE PROCESS...ENHANCING LL CONVERGENCE. HAVE ISSUED A WINTER STORM WARNING FOR BERRIEN AND CASS COUNTIES...WITH 1 TO 2 INCHES OF SNOWFALL THIS MORNING/PERIODS OF LAKE EFFECT SNOW THIS AFTERNOON WITH AND ADDITIONAL 2 TO 3 INCHES POSSIBLE/BLOWING SNOW THROUGH THE DAY AND NIGHT SIGNIFICANTLY REDUCING VISIBILITIES/AND ADDITIONAL HEAVY LAKE EFFECT SNOW WITH AN ADDITIONAL 4 TO 8 INCHES POSSIBLE. OPTED FOR A WINTER WEATHER ADV FOR ST. JOE IN/MI AND ELKHART FOR COMBINATION OF LAKE EFFECT SNOW AND BLOWING SNOW WITH 3 TO 6 INCHES POSSIBLE BY SUNDAY MORNING. IT IS QUITE POSSIBLE THAT LAGRANGE AND MAYBE NOBLE COUNTIES MAY HAVE TO BE ADDED TO THE ADV AS CURRENT MODEL GUIDANCE CERTAINLY HINTS AT A PERIOD OF INTENSE LL OMEGA CENTERED OVER THESE COUNTIES. HEAVIEST LAKE SNOWS WILL OCCUR SAT EVENING AND BEGIN TO DIMINISH SUN MORNING WITH FALLING INVERSION HEIGHTS AND SFC RIDGING SHIFTING WINDS TO THE SW. TEMPS WILL REMAIN COLD THROUGH THE PERIOD WITH HIGHS RAGING 10 TO 15 DEGREES BELOW NORMAL. HAVE OPTED TO UNDERCUT GUIDANCE TEMPS GIVEN ANOMALOUSLY COLD CONDITIONS PRESENT. && .LONG TERM... ...MONDAY THROUGH FRIDAY... COMPLICATED AND LOW CONFIDENCE LONG TERM FORECAST DUE TO HIGHLY ENERGETIC AND COMPLICATED MID AND UPPER LEVEL FLOW OVER PACIFIC AND WESTERN NORTH AMERICA. STILL EXPECT BELOW NORMAL TEMPERATURES FOR A LARGE PART OF THE PERIOD AND POTENTIAL FOR A MODERATE TO HEAVY PRECIPITATION EVENT MID WEEK. WATER VAPOR THIS MORNING SHOWS A VERY ENERGETIC PATTERN...SIMILAR TO LAST YEAR ABOUT THIS TIME. AS DISCUSSED LAST NIGHT...MODELS LIKELY NOT RESOLVING FEATURES OVER THE PACIFIC WELL GIVEN LIMITED SAMPLING MEASURES. FIRST AREA OF CONCERN IS WITH IMPRESSIVE LOOKING SUB-TROPICAL MOISTURE PLUME DEVELOPING NEAR 15N AND 120W. MODELS TRYING TO PICK UP ON THIS BUT CONCERNED THEY ARE NOT NEAR STRONG ENOUGH GIVEN DEPICTION IN WATER VAPOR. THIS AREA EXPECTED TO CONTINUE SPREADING NORTHEAST AND WILL FEED INTO DEVELOPING MID LEVEL LOW OFF OF CA COAST THAT WILL BECOME OUR WEATHER MAKER FOR MID WEEK. SECONDARY AREA OF CONCERN IS WITH STRONG JET CORE NEAR 40N AND 150W. MODELS DO SEEM TO HAVE A HANDLE ON THIS FEATURE...BUT GIVEN ITS STRENGTH THERE IS SOME CONCERN WITH HOW IT WILL EVOLVE OVER WESTERN CONUS. THIS IS A LARGE PART OF THE DIFFERENCES IN MODEL SOLUTIONS FOR MID WEEK. IT WILL BE THE INTERACTION OF THESE TWO PACIFIC FEATURES WITH THE MID LEVEL LOW ACROSS THE SOUTHWEST CONUS THAT DETERMINES ITS EVOLUTION AND IMPACT ON OUR AREA. AS MENTIONED LAST NIGHT...WE FELT MODELS WERE NOT HANDLING THIS ENERGY WELL AND A STRONGER SYSTEM WAS EXPECTED. LATEST MEDIUM RANGE SOLUTIONS ARE INDEED STRONGER...WITH GFS BEING THE STRONGEST. COMPLICATIONS FOR OUR FORECAST AREA WILL BE WITH AMOUNT OF WARM AIR ADVECTION AHEAD OF SYSTEM AND ITS ACTUAL TRACK. ECMWF WHILE WEAKER IS FURTHER NORTH WITH STRONG WAA AND MOISTURE INFLUX INTO THE AREA LATE MONDAY NIGHT AND TUESDAY...INDICATING A POSSIBLE HEAVY RAIN EVENT. GFS IS STRONGER AND FURTHER SOUTH WITH COLDER AIR OVER NORTHERN HALF OF FORECAST AREA...YIELDING A POSSIBLE RAIN EVENT SOUTH AND SNOW NORTH. BOTH SOLUTIONS PLAUSIBLE AND AGAIN WILL LIKELY NOT BE RESOLVED UNTIL SYSTEM GETS WITHIN RADIOSONDE NETWORK. AGREEMENT LIES WITH SOME TYPE OF PRECIPITATION EVENT WITH POTENTIAL FOR HEAVY PCPN SOMEWHERE IN THE WESTERN LAKES OR OHIO VALLEY REGION FROM LATE MONDAY NIGHT INTO EARLY WEDNESDAY. HAVE INCREASED POPS DURING THIS WINDOW WITH LIKELY POPS CENTERED ON TUESDAY. STAYED WITH ALL SNOW MONDAY NIGHT WITH INITIAL COLDER AIR IN PLACE AND LOWER WET BULB TEMPERATURES. ALSO STAYED WITH RAIN OR SNOW MENTION TUESDAY GIVEN UNCERTAINTY IN TRACK AND THERMAL FIELDS. BEYOND WEDNESDAY FEW CHANGES WERE MADE. MODELS CONTINUE TO INDICATE SOME TYPE OF COLDER AIR INTRUSION BUT NOT NEAR AS STRONG AS 48 HOURS AGO. THUS KEPT IDEA OF SLIGHTLY BELOW NORMAL TEMPERATURES. CLIPPER SYSTEM POSSIBLE BY END OF WEEK BUT AGAIN QUITE A BIT OF DISAGREEMENT IN MODELS SO NO CHANGES MADE. SOME SIGNALS TO A PATTERN CHANGE WELL BEYOND DAY 7...TOWARD MID MONTH. ENSEMBLES SHOWING WESTERN CONUS RIDGE BEING REPLACED BY DEEP TROUGH WITH FLOW OVER OUR AREA BECOMING MORE SOUTHWEST AND POSSIBLY ACTIVE. && AVIATION.../06Z TAFS/ CLIPPER SYSTEM WILL MOVE THROUGH THE REGION DURING THE PERIOD...BRINGING DETERIORATING FLIGHT CONDITIONS TO THE REGION. EXPECTING A PERIOD OF MVFR CIGS/VISBY WITH THE SYNOPTIC SYSTEM AT SBN AND FWA. THIS LINES UP WELL WITH MOS AND UPSTREAM OBS. STRONG GUSTY SOUTHERLY WINDS WILL BE EXPECTED GIVEN VERY STRONG FLOW OFF THE SFC AND A TIGHT PRESSURE GRADIENT IN PLACE. COLD FRONT WILL PUSH THROUGH THE REGION LATE MORNING AND EARLY AFTERNOON...ALLOWING WINDS TO VEER WESTERLY. GUSTS OF 25 TO 30 KNOTS WILL SUPPORT AREAS OF BLOWING SNOW...WHICH COULD ALLOW FOR BRIEF VISBY REDUCTIONS ACROSS THE FA. LAKE EFFECT SNOWS WILL DEVELOP AND SHIFT SOUTH INTO THE NORTHWEST FA...WITH IFR/LIFR CONDITIONS LIKELY THERE BY EVENING IN A COMBINATION OF BLOWING SNOW AND HEAVY LAKE SNOWS. HAVE TRENDED SBN IN THIS DIRECTION. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 7 AM EST SUNDAY FOR INZ004-005. MI...WINTER STORM WARNING UNTIL 7 AM EST SUNDAY FOR MIZ077-078. WINTER WEATHER ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ079. OH...NONE. LM...GALE WARNING UNTIL 3 AM EST SUNDAY FOR LMZ043-046. && $$ SHORT TERM...JC LONG TERM...LASHLEY AVIATION...JC in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mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 402 AM EST SAT DEC 6 2008 .SYNOPSIS...CHILLY HIGH PRESSURE WILL BUILD INTO NORTH CAROLINA FROM THE WEST OVERNIGHT...QUICKLY MOVING OFFSHORE DURING THE DAY ON SATURDAY. A STRONG UPPER LEVEL DISTURBANCE AND SURFACE COLD FRONT WILL SWING EAST THROUGH THE AREA SATURDAY EVENING...BRINGING A REINFORCING SHOT OF COLDER AND DRIER INTO THE REGION THROUGH MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM SATURDAY... HIGH PRESSURE BUILDING OVER THE AREA WILL RESULT IN SOME SUN THROUGH THE LATE MORNING. CLOUDINESS WILL INCREASE FROM THE NORTHWEST... AS A LOW PRESSURE CENTER OVER THE GREAT LAKES WITH ITS ASSOCIATED COLD FRONT APPROACHES THE REGION FROM THE NORTH THIS AFTERNOON AND SWEEPS ACROSS THE AREA TONIGHT. THERE ARE SOME DIFFERENCES IN THE MODELS... SOUNDING DATA DOES SHOW THE GFS HAS SOME LOW LEVEL MOISTURE DURING THE AFTERNOON AROUND 5 THOUSAND FEET... WHILE THE NAM IS SOMEWHAT DRY THROUGH THE COLUMN. THE CHANCE OF PRECIPITATION WILL REMAIN IN THE SLIGHT CHANCE CATEGORY... AND WILL KEEP THE SLIGHT CHANCE OF RAIN OR SNOW ACROSS THE NORTHERN PORTION SINCE PASSING THROUGH VERY DRY...COLD AIR AT THE SURFACE A FEW FLAKES MAY MAKE TO THE SURFACE. HIGHS WILL RANGE FROM THE MID 40S IN THE NORTHWEST TO THE LOWER 50S IN THE SOUTHEAST. LOWS TONIGHT WILL RANGE FROM THE MID 20S ACROSS THE NORTHWEST TO THE MID 30S OVER THE SOUTHEAST. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 310 AM SATURDAY... POLAR HIGH PRESSURE WILL BUILD OVER THE REGION FROM THE NORTHWEST ON SUNDAY. THIS SYSTEM COMBINED WITH STRONG UPPER LEVEL TROUGH TO THE NORTH/NORTHEAST WILL RESULT IN STRONG GUSTY WINDS. SUSTAINED SURFACE WINDS WILL BE AROUND 15 MPH WITH POSSIBLE GUSTS TO AT LEAST 25 MPH. WITH THE STRONG COLD AIR ADVECTION PREFER THE MET GUIDANCE... WITH HIGHS IN THE LOWER 40S NORTHWEST TO AROUND 50 IN THE SOUTHEAST. HIGH PRESSURE WILL SETTLE OVER THE AREA TONIGHT. LOWS WILL BE IN THE 20S. AS THE SURFACE FEATURE MOVES EAST AND WINDS SHIFT TO THE SOUTH... WE CAN EXPECT AN INCREASE IN TEMPERATURES. THERE WILL ALSO BE AN INCREASE IN MOISTURE AND CLOUDS DUE TO THE SOUTHERLY FLOW AT THE SURFACE... AND ALOFT AS WESTERLY FLOW ADVECTS MOISTURE EASTWARD FROM A DEVELOPING SYSTEM OVER TEXAS. HIGHS WILL RANGE FROM THE MID 40S TO LOWER 50S. CLOUDS COVER MONDAY NIGHT WILL HOLD TEMPERATURES IN THE 30S. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 400 AM... WHEELS QUICKLY FALL OFF THE WAGON AS SIGNIFICANT MODEL DIFFERENCES BEGIN TO APPEAR BEYOND 48 HOURS (MONDAY MORNING) AT 500 MILLIBARS. PLACEMENT AND STRENGTH OF SHORT WAVE ENERGY PROFOUNDLY AFFECT THE FORECAST AND CONFIDENCE PRETTY MUCH APPROACHES ZERO REGARDING THE LATER PERIODS (THURSDAY NIGHT AND FRIDAY). SURFACE HIGH PRESSURE WELL OFFSHORE TUESDAY MORNING WITH PRESSURE GRADIENTS TIGHTENING SURFACE AND ALOFT THROUGHOUT THE DAY. WITH TEMPERATURES WARMING ALOFT AND SOUTHWEST FLOW INCREASING... ISENTROPIC LIFT OVER THE SURFACE COOL POOL COULD PRODUCE RAIN. LIMITED MOISTURE SEEMS TO BE THE LIMITING FACTOR PREVENTING RAIN CHANCES FROM GOING TO LIKELY OR HIGHER IN THIS FORECAST FOR TUESDAY. COLD FRONT APPROACHES THE MOUNTAINS TUESDAY NIGHT. WINDS INCREASE TO 45 KNOTS OR HIGHER JUST OFF THE SURFACE WEDNESDAY AND GFS MODEL HELICITY QUITE LARGE AT 12Z WEDNESDAY (GREATER THAN 350). LCL LESS THAN 2500 FEET. THE HOPE IS THAT AN EARLY RAIN AND LOW CLOUDINESS PROVIDE ENOUGH SURFACE STABILITY TO MAKE THIS A NON SEVERE EVENT. THIS IS THE CURRENT THINKING BUT THE MARGIN FOR ERROR IS SLIM. THIS EVENT WILL HAVE TO BE CLOSELY WATCHED. TIMING WOULD BE FOR A DAYTIME EVENT WEDNESDAY. HAVE RAISED RAIN CHANCES TO HIGH LIKELY WEDNESDAY WITH THE THOUGHT CHANCES WILL GO CATEGORICAL IN FUTURE FORECASTS. RAINFALL AMOUNTS IN EXCESS OF ONE HALF INCH EXPECTED AT THIS TIME. ECMWF FORECASTS ANOTHER GULF LOW TO LIFT NORTHEAST FRIDAY PRODUCING ANOTHER RAIN EVENT THURSDAY NIGHT AND FRIDAY. ITS TRACK HAS THE LOW SOUTHEAST OF CENTRAL NORTH CAROLINA WHICH COULD BE PROBLEMATIC FOR THE END OF THE EVENT REGARDING PRECIPITATION TYPE. AS STATED EARLIER... CONFIDENCE IS LESS THAN LOW... AND WILL LEAVE SMALL RAIN CHANCES CURRENTLY FORECAST ALONE AT THIS TIME AS HAVE NO CONFIDENCE IN WHICH WAY TO SHIFT THEM. EXPECTING TEMPERATURES TO RISE OVERNIGHT TUESDAY NIGHT AHEAD OF THE FRONT WITH LOW TEMPERATURES OCCURRING WELL BEFORE MIDNIGHT. GFS IS TOO DEEP WITH THE APPROACHING LOW AND THEREFORE ADVECTS TOO MUCH WARMTH INTO NORTH CAROLINA. HOWEVER TEMPERATURES IN THE 50S SUNRISE WEDNESDAY LIKELY FOR MOST OF CENTRAL NORTH CAROLINA. AS FRONT SWEEPS THROUGH THE REGION... TEMPERATURES NOT LIKELY TO RISE MUCH AND THEN FALL DURING THE AFTERNOON... IF THE CURRENT TIMING HOLDS TRUE. WEDNESDAY HIGHS IN THE FIFTIES. MORNING LOWS FALL INTO THE MID TO UPPER 30S THURSDAY MORNING BEFORE DROPPING SIX TO EIGHT DEGREES FRIDAY MORNING. THURSDAY HIGHS IN THE 40S WITH LOW 50S FRIDAY. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... AS OF 130 AM... CIRRUS LEVEL MOISTURE EARLY THIS MORNING SHOULD PUSH EAST BY MID MORNING. LARGE PATCH OF STRATUS NEAR 6000 FEET OVER THE NORTHERN FOOTHILLS AND NORTHWEST PIEDMONT WITH ISOLATED CEILINGS AT THIS LEVEL AT TIMES WEST OF THE COASTAL PLAIN. ROCKY MOUNT WITH LOCALIZED LIFR CEILING AT TIMES UNTIL SHORTLY AFTER SUNRISE. RUC MODEL IS SHOWING STRATUS DISSIPATING TOWARD SUNRISE AS MID LEVEL WINDS BECOME PARALLEL TO THE MOUNTAINS AND THIS IS ACCEPTED. MODELS MOSTLY IN AGREEMENT IN DEVELOPING A LOW OFF THE CAROLINA COAST AS MOISTURE INCREASES ON SOUTHWEST WINDS ALOFT. FREEZING LEVELS DROPPING BELOW 10000 FEET IN THE NORTH TONIGHT WITH TINY PRECIPITATION CHANCES AFTER SUNSET... MAINLY NORTH OF HIGHWAY 64. VFR CONDITIONS EXPECTED SATURDAY NIGHT INTO MONDAY NIGHT. COMPUTER MODELS CONTINUE TO SHOW A DEVELOPING STORM SYSTEM WELL TO OUR SOUTHWEST TOWARD MID WEEK THAT MAY PRODUCE VARIOUS ADVERSE AVIATION CONDITIONS FROM TUESDAY THROUGH WEDNESDAY AND POSSIBLY BEYOND... SO AVIATION INTERESTS SHOULD STAY TUNED FOR LATER FORECASTS. && .FIRE WEATHER... MARGINALLY ADVERSE FIRE WEATHER CONDITIONS ARE POSSIBLE ON SUNDAY. THE COMBINATION OF DEEPENING LOW PRESSURE AND STRONG HIGH PRESSURE BUILDING IN FROM THE WEST WILL PRODUCE SUSTAINED WINDS AROUND 15 MPH AND GUSTS TO AROUND 25 MPH ON SUNDAY. IN ADDITION... AS VERY DRY LOW LEVEL AIR SPILLS INTO THE AREA... RELATIVE HUMIDITIES WILL BOTTOM OUT AT 21-26 PERCENT IN THE EARLY TO MID AFTERNOON. THOSE WITH FIRE WEATHER INTERESTS SHOULD KEEP A CLOSE EYE ON THE LATEST FORECASTS AND CONDITIONS THROUGH THE WEEKEND. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RHJ NEAR TERM...RHJ SHORT TERM...RHJ nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 310 AM EST SAT DEC 6 2008 .SYNOPSIS... CHILLY HIGH PRESSURE WILL BUILD OVER THE REGION FROM THE WEST... CONTINUE TO THE EAST TODAY... THEN MOVE OFFSHORE THIS EVENING. AN ALBERTA CLIPPER WITH ITS ASSOCIATED COLD FRONT WILL MOVE THROUGH THE REGION THIS EVENING. COLD HIGH PRESSURE WILL ONCE AGAIN TAKE ITS GRIP ON CENTRAL NORTH CAROLINA ON SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM SATURDAY... HIGH PRESSURE BUILDING OVER THE AREA WILL RESULT IN SOME SUN THROUGH THE LATE MORNING. CLOUDINESS WILL INCREASE FROM THE NORTHWEST... AS A LOW PRESSURE CENTER OVER THE GREAT LAKES WITH ITS ASSOCIATED COLD FRONT APPROACHES THE REGION FROM THE NORTH THIS AFTERNOON AND SWEEPS ACROSS THE AREA TONIGHT. THERE ARE SOME DIFFERENCES IN THE MODELS... SOUNDING DATA DOES SHOW THE GFS HAS SOME LOW LEVEL MOISTURE DURING THE AFTERNOON AROUND 5 THOUSAND FEET... WHILE THE NAM IS SOMEWHAT DRY THROUGH THE COLUMN. THE CHANCE OF PRECIPITATION WILL REMAIN IN THE SLIGHT CHANCE CATEGORY... AND WILL KEEP THE SLIGHT CHANCE OF RAIN OR SNOW ACROSS THE NORTHERN PORTION SINCE PASSING THROUGH VERY DRY...COLD AIR AT THE SURFACE A FEW FLAKES MAY MAKE TO THE SURFACE. HIGHS WILL RANGE FROM THE MID 40S IN THE NORTHWEST TO THE LOWER 50S IN THE SOUTHEAST. LOWS TONIGHT WILL RANGE FROM THE MID 20S ACROSS THE NORTHWEST TO THE MID 30S OVER THE SOUTHEAST. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 310 AM SATURDAY... POLAR HIGH PRESSURE WILL BUILD OVER THE REGION FROM THE NORTHWEST ON SUNDAY. THIS SYSTEM COMBINED WITH STRONG UPPER LEVEL TROUGH TO THE NORTH/NORTHEAST WILL RESULT IN STRONG GUSTY WINDS. SUSTAINED SURFACE WINDS WILL BE AROUND 15 MPH WITH POSSIBLE GUSTS TO AT LEAST 25 MPH. WITH THE STRONG COLD AIR ADVECTION PREFER THE MET GUIDANCE... WITH HIGHS IN THE LOWER 40S NORTHWEST TO AROUND 50 IN THE SOUTHEAST. HIGH PRESSURE WILL SETTLE OVER THE AREA TONIGHT. LOWS WILL BE IN THE 20S. AS THE SURFACE FEATURE MOVES EAST AND WINDS SHIFT TO THE SOUTH... WE CAN EXPECT AN INCREASE IN TEMPERATURES. THERE WILL ALSO BE AN INCREASE IN MOISTURE AND CLOUDS DUE TO THE SOUTHERLY FLOW AT THE SURFACE... AND ALOFT AS WESTERLY FLOW ADVECTS MOISTURE EASTWARD FROM A DEVELOPING SYSTEM OVER TEXAS. HIGHS WILL RANGE FROM THE MID 40S TO LOWER 50S. CLOUDS COVER MONDAY NIGHT WILL HOLD TEMPERATURES IN THE 30S. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 300 PM FRIDAY... AN UNSETTLED WEATHER PATTERN IS STILL EXPECTED DURING THIS PORTION OF THE FORECAST. HOWEVER...SPECIFICS REMAIN DIFFICULT TO PIN DOWN DUE TO CONTINUED DIFFERENCES IN HOW THE LONG RANGE MODELS HANDLE NORTHERN/SOUTHERN STREAM PHASING. ON TUESDAY AN UPPER LEVEL WAVE IS EXPECTED TO DIG SOUTH THROUGH THE INTERMOUNTAIN WEST...INTO THE FAR WESTERN GOMEX BY WED. THIS WILL HELP PUSH A FRONTAL ZONE TOWARD THE AREA FROM THE WEST...IN ADDITION TO ALLOWING A MOIST SOUTHWEST FLOW ALOFT (FROM THE GOMEX) TO SETUP OVER THE SOUTHEAST STATES. AS OF THE LATEST 12Z MODEL RUNS...WED LOOKS LIKE A BETTER CHANCE FOR PRECIP THAN TUE...ALTHOUGH QUITE A BIT OF UNCERTAINTY REMAINS THROUGH MID/LATE WEEK. BOTH THE GFS/ECMWF SHOW THE UPPER LEVEL WAVE THAT DIGS INTO THE WESTERN GOMEX CLOSING OFF INTO AN UPPER LOW THURSDAY...WHICH SUBSEQUENTLY MOVES EAST ACROSS THE NORTHERN GOMEX AND THEN NORTHEAST THROUGH THE SOUTHEAST STATES...WITH A SFC LOW DEVELOPING IN THE GULF AND MOVING NORTHEAST ALONG THE SOUTHEAST COAST ON THU/FRI. ALTHOUGH THE GFS/ECMWF ARE NOW SHOWING A MORE SIMILAR PATTERN THROUGH MID/LATE NEXT WEEK...THERE ARE STILL TIMING DIFFERENCES...AND THERE IS ENOUGH UNCERTAINTY TO LEAVE THE EXTENDED FORECAST MORE OR LESS AS IS...WITH THE EXCEPTION OF SOME MINOR TWEAKING TO POPS AND TEMPS. WILL BASICALLY SHOW CHANCE POPS FROM TUE THROUGH FRI...WITH MOSTLY CLOUDY OR OVERCAST SKIES DURING THE ENTIRE PERIOD. TEMPERATURES REMAIN DIFFICULT TO FCST IN THIS PERIOD SINCE THEY WILL HIGHLY DEPEND ON THE TIMING OF FRONTAL PASSAGES... ONSET/DURATION OF PRECIP...AND THE TRACK OF ANY SFC LOW THAT MAY DEVELOP BY MID/LATE WEEK. AT THIS TIME WILL SHOW NEAR NORMAL TEMPS ON TUE/WED...WITH BELOW NORMAL TEMPS ON THU/FRI. -VINCENT && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 130 AM... CIRRUS LEVEL MOISTURE EARLY THIS MORNING SHOULD PUSH EAST BY MID MORNING. LARGE PATCH OF STRATUS NEAR 6000 FEET OVER THE NORTHERN FOOTHILLS AND NORTHWEST PIEDMONT WITH ISOLATED CEILINGS AT THIS LEVEL AT TIMES WEST OF THE COASTAL PLAIN. ROCKY MOUNT WITH LOCALIZED LIFR CEILING AT TIMES UNTIL SHORTLY AFTER SUNRISE. RUC MODEL IS SHOWING STRATUS DISSIPATING TOWARD SUNRISE AS MID LEVEL WINDS BECOME PARALLEL TO THE MOUNTAINS AND THIS IS ACCEPTED. MODELS MOSTLY IN AGREEMENT IN DEVELOPING A LOW OFF THE CAROLINA COAST AS MOISTURE INCREASES ON SOUTHWEST WINDS ALOFT. FREEZING LEVELS DROPPING BELOW 10000 FEET IN THE NORTH TONIGHT WITH TINY PRECIPITATION CHANCES AFTER SUNSET... MAINLY NORTH OF HIGHWAY 64. VFR CONDITIONS EXPECTED SATURDAY NIGHT INTO MONDAY NIGHT. COMPUTER MODELS CONTINUE TO SHOW A DEVELOPING STORM SYSTEM WELL TO OUR SOUTHWEST TOWARD MID WEEK THAT MAY PRODUCE VARIOUS ADVERSE AVIATION CONDITIONS FROM TUESDAY THROUGH WEDNESDAY AND POSSIBLY BEYOND... SO AVIATION INTERESTS SHOULD STAY TUNED FOR LATER FORECASTS. && .FIRE WEATHER... MARGINALLY ADVERSE FIRE WEATHER CONDITIONS ARE POSSIBLE ON SUNDAY. THE COMBINATION OF DEEPENING LOW PRESSURE AND STRONG HIGH PRESSURE BUILDING IN FROM THE WEST WILL PRODUCE SUSTAINED WINDS AROUND 15 MPH AND GUSTS TO AROUND 25 MPH ON SUNDAY. IN ADDITION... AS VERY DRY LOW LEVEL AIR SPILLS INTO THE AREA... RELATIVE HUMIDITIES WILL BOTTOM OUT AT 21-26 PERCENT IN THE EARLY TO MID AFTERNOON. THOSE WITH FIRE WEATHER INTERESTS SHOULD KEEP A CLOSE EYE ON THE LATEST FORECASTS AND CONDITIONS THROUGH THE WEEKEND. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RHJ NEAR TERM...RHJ SHORT TERM...RHJ LONG TERM...VINCENT FIRE WEATHER...BADGETT nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 130 AM EST SAT DEC 6 2008 .SYNOPSIS... CHILLY HIGH PRESSURE WILL CONTINUE TO BUILD IN FROM THE WEST. THIS HIGH WILL QUICKLY MOVE EAST AND OFFSHORE BY LATE SATURDAY... AND THEN AN ALBERTA CLIPPER AND ATTENDANT SURFACE COLD FRONT SWINGS THROUGH THE MID ATLANTIC REGION SATURDAY EVENING. COLD HIGH PRESSURE WILL AGAIN BUILD INTO THE AREA ON SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 915 PM FRIDAY... ONLY MINOR CHANGES TO GRIDDED DATABASE. OCCASIONAL SCATTERED HIGH CLOUDINESS...ASSOCIATED WITH THE RIGHT ENTRANCE DIVERGENCE REGION OF THE POLAR JET...WILL PRODUCE MOSTLY CLEAR TO FAIR SKIES OVERNIGHT. MANUAL SURFACE ANALYSIS COLD FRONT HAS PUSHED OFFSHORE...WITH A WEAKENING 1027 MB SURFACE HIGH BUILDING IN FROM THE TENNESSEE VALLEY. THERE REMAINS A PROMINENT DEWPOINT DISCONTINUITY ACROSS THE FORECAST AREA...WITH DEWPOINTS IN THE MID TO UPPER TEENS IN THE NW PIEDMONT...WITH DEWPOINT ACROSS THE CENTRAL PIEDMONT AND COASTAL PLAINS STAYING UP IN THE UPPER 20S TO LOWER 30S. WINDS ARE LIGHT OR CALM ACROSS CENTRAL NC....AND THIS WILL SET THE STAGE FOR GOOD RADIATIONAL COOLING...WITH A RATHER LARGE SPREAD DUE TO THE LARGE DEWPOINT GRADIENT. EXPECT LOWS OF IN THE MID 20S NW PIEDMONT...TO NEAR FREEZING SOUTHEAST. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... AS OF 235 PM FRIDAY... FOR SATURDAY/SATURDAY NIGHT: SATURDAY SHOULD BEGIN WITH A GOOD BIT OF SUNSHINE BUT WITH INCREASING HIGH CLOUDS TOWARD MIDDAY. A CLIPPER SYSTEM IS STILL EXPECTED TO DROP THROUGH THE MIDWEST LATE FRIDAY NIGHT INTO SATURDAY MORNING... THEN PASS THROUGH NC AND OFF COAST SATURDAY NIGHT. THE NAM REMAINS MORE SUBDUED WITH THIS VORTICITY MAXIMUM AS COMPARED TO THE GFS... WEAKENING IT IN FAVOR OF A STRONGER MAXIMUM TO ITS NW... HOWEVER THERE HAS BEEN A GENERAL MODEL TREND TOWARD A STRONGER WAVE WITH MORE DYNAMIC LIFT AS IT APPROACHES. THE 12Z WRF-ARW IS GENERATING LIGHT PRECIP AMOUNTS ACROSS NORTH CENTRAL NC VERY LATE SATURDAY AFTERNOON THROUGH THE EVENING... AND THE 12Z GFS HAS TRENDED TOWARD GREATER QPF AS WELL... GENERATING SEVERAL HUNDREDTHS LIQUID ACROSS THE ENTIRE PIEDMONT. GIVEN THIS TREND... WILL SLIGHTLY EXPAND AREALLY THE SLIGHT CHANCE POPS SATURDAY AFTERNOON... SWEEPING THEM EAST AND RAISING THEM TO 20-30% SATURDAY EVENING. FORECAST WET BULB PROFILES ARE PRIMARILY BELOW FREEZING EXCEPT FOR THE LOWEST COUPLE THOUSAND FEET WHERE THE AIR IS ALSO MARKEDLY DRIER. BUT GFS FORECAST SOUNDINGS SHOW NEAR SATURATION UP TO -20C... SO A PRECIP TYPE OF LIGHT RAIN AT ONSET AND A MIXTURE OF LIGHT RAIN AND LIGHT SNOW IN THE EVENING NORTH OF HIGHWAY 64 WILL BE RETAINED. THE LOW LEVEL DRY AIR AND APPARENT LACK OF CONCENTRATED STRONG FORCING FOR ASCENT SHOULD LIMIT AMOUNTS SO AS TO BE INSIGNIFICANT... HOWEVER IF IT APPEARS THAT LIFT WILL BE BRIEFLY ENHANCED... WE MAY SEE A SHORT PERIOD OF MOSTLY SNOW MAINLY NEAR THE VA BORDER... BUT AGAIN THE BREVITY OF ANY SUCH OCCURRENCE SHOULD RENDER IT INSIGNIFICANT FOR TRAVELERS. THICKNESSES AND STATISTICAL GUIDANCE AGREE ON HIGHS OF 45-52. LOWS SATURDAY NIGHT 26-34 WITH INCREASING COLD ADVECTION BEHIND THE EXITING WAVE. FOR SUNDAY: THE MID LEVEL LONGWAVE TROUGH AXIS SHIFTS TO OUR NE SUNDAY MORNING AS THE POLAR HIGH BUILDS IN FROM THE NW... AND CONSIDERABLE SUNSHINE IS EXPECTED. WITH RAPIDLY DEEPENING SURFACE PRESSURES OVER THE NORTHEAST STATES... THE RESULTING TIGHTENING MSLP GRADIENT WILL PRODUCE BLUSTERY SURFACE WINDS AROUND 15 MPH WITH GUSTS TO AROUND 25 MPH POSSIBLE (SEE FIRE WEATHER DISCUSSION BELOW). WITH STRONG COLD ADVECTION AND CONSIDERING THE POLAR SOURCE OF THE INCOMING SURFACE HIGH... HAVE LOWERED HIGHS A BIT TO 41-48. -GIH && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... AS OF 300 PM FRIDAY... MONDAY: THE LATEST 12Z MODEL RUNS CONTINUE TO SHOW SFC HIGH PRESSURE BUILDING ACROSS THE AREA FROM THE WEST ON SUNDAY NIGHT AND MONDAY...WITH UNIDIRECTIONAL FLOW ALOFT. CLEAR SKIES AND NEAR CALM WINDS WILL ALLOW EXCELLENT RADIATIONAL COOLING MON MORNING...AND EXPECT VERY CHILLY LOW TEMP READINGS IN THE LOWER/MID 20S. CLEAR SKIES WILL EVENTUALLY GIVE WAY TO INCREASING MID/UPPER LEVEL CLOUDS BY THE AFT/EVE AS UPPER LEVEL MOISTURE ADVECTS DOWNSTREAM OF AN AREA OF LOW PRESSURE EXPECTED TO DEVELOP ACROSS THE LOWER MIDWEST. FOR TEMPS...WENT WITH A BLEND OF MOS GUIDANCE AND THICKNESSES (1285- 1295M AT 12Z MON UP TO 1310-1325M BY 00Z TUE)...WHICH SUGGEST HIGHS RANGING FROM THE MID 40S TO LOWER 50S. TUESDAY THROUGH FRIDAY: AN UNSETTLED WEATHER PATTERN IS STILL EXPECTED DURING THIS PORTION OF THE FORECAST. HOWEVER...SPECIFICS REMAIN DIFFICULT TO PIN DOWN DUE TO CONTINUED DIFFERENCES IN HOW THE LONG RANGE MODELS HANDLE NORTHERN/SOUTHERN STREAM PHASING. ON TUESDAY AN UPPER LEVEL WAVE IS EXPECTED TO DIG SOUTH THROUGH THE INTERMOUNTAIN WEST...INTO THE FAR WESTERN GOMEX BY WED. THIS WILL HELP PUSH A FRONTAL ZONE TOWARD THE AREA FROM THE WEST...IN ADDITION TO ALLOWING A MOIST SOUTHWEST FLOW ALOFT (FROM THE GOMEX) TO SETUP OVER THE SOUTHEAST STATES. AS OF THE LATEST 12Z MODEL RUNS...WED LOOKS LIKE A BETTER CHANCE FOR PRECIP THAN TUE...ALTHOUGH QUITE A BIT OF UNCERTAINTY REMAINS THROUGH MID/LATE WEEK. BOTH THE GFS/ECMWF SHOW THE UPPER LEVEL WAVE THAT DIGS INTO THE WESTERN GOMEX CLOSING OFF INTO AN UPPER LOW THURSDAY...WHICH SUBSEQUENTLY MOVES EAST ACROSS THE NORTHERN GOMEX AND THEN NORTHEAST THROUGH THE SOUTHEAST STATES...WITH A SFC LOW DEVELOPING IN THE GULF AND MOVING NORTHEAST ALONG THE SOUTHEAST COAST ON THU/FRI. ALTHOUGH THE GFS/ECMWF ARE NOW SHOWING A MORE SIMILAR PATTERN THROUGH MID/LATE NEXT WEEK...THERE ARE STILL TIMING DIFFERENCES...AND THERE IS ENOUGH UNCERTAINTY TO LEAVE THE EXTENDED FORECAST MORE OR LESS AS IS...WITH THE EXCEPTION OF SOME MINOR TWEAKING TO POPS AND TEMPS. WILL BASICALLY SHOW CHANCE POPS FROM TUE THROUGH FRI...WITH MOSTLY CLOUDY OR OVERCAST SKIES DURING THE ENTIRE PERIOD. TEMPERATURES REMAIN DIFFICULT TO FCST IN THIS PERIOD SINCE THEY WILL HIGHLY DEPEND ON THE TIMING OF FRONTAL PASSAGES... ONSET/DURATION OF PRECIP...AND THE TRACK OF ANY SFC LOW THAT MAY DEVELOP BY MID/LATE WEEK. AT THIS TIME WILL SHOW NEAR NORMAL TEMPS ON TUE/WED...WITH BELOW NORMAL TEMPS ON THU/FRI. -VINCENT && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... AS OF 130 AM... CIRRUS LEVEL MOISTURE EARLY THIS MORNING SHOULD PUSH EAST BY MID MORNING. LARGE PATCH OF STRATUS NEAR 6000 FEET OVER THE NORTHERN FOOTHILLS AND NORTHWEST PIEDMONT WITH ISOLATED CEILINGS AT THIS LEVEL AT TIMES WEST OF THE COASTAL PLAIN. ROCKY MOUNT WITH LOCALIZED LIFR CEILING AT TIMES UNTIL SHORTLY AFTER SUNRISE. RUC MODEL IS SHOWING STRATUS DISSIPATING TOWARD SUNRISE AS MID LEVEL WINDS BECOME PARALLEL TO THE MOUNTAINS AND THIS IS ACCEPTED. MODELS MOSTLY IN AGREEMENT IN DEVELOPING A LOW OFF THE CAROLINA COAST AS MOISTURE INCREASES ON SOUTHWEST WINDS ALOFT. FREEZING LEVELS DROPPING BELOW 10000 FEET IN THE NORTH TONIGHT WITH TINY PRECIPITATION CHANCES AFTER SUNSET... MAINLY NORTH OF HIGHWAY 64. VFR CONDITIONS EXPECTED SATURDAY NIGHT INTO MONDAY NIGHT. COMPUTER MODELS CONTINUE TO SHOW A DEVELOPING STORM SYSTEM WELL TO OUR SOUTHWEST TOWARD MID WEEK THAT MAY PRODUCE VARIOUS ADVERSE AVIATION CONDITIONS FROM TUESDAY THROUGH WEDNESDAY AND POSSIBLY BEYOND... SO AVIATION INTERESTS SHOULD STAY TUNED FOR LATER FORECASTS. && .FIRE WEATHER... MARGINALLY ADVERSE FIRE WEATHER CONDITIONS ARE POSSIBLE ON SUNDAY. THE COMBINATION OF DEEPENING LOW PRESSURE AND STRONG HIGH PRESSURE BUILDING IN FROM THE WEST WILL PRODUCE SUSTAINED WINDS AROUND 15 MPH AND GUSTS TO AROUND 25 MPH ON SUNDAY. IN ADDITION... AS VERY DRY LOW LEVEL AIR SPILLS INTO THE AREA... RELATIVE HUMIDITIES WILL BOTTOM OUT AT 21-26 PERCENT IN THE EARLY TO MID AFTERNOON. THOSE WITH FIRE WEATHER INTERESTS SHOULD KEEP A CLOSE EYE ON THE LATEST FORECASTS AND CONDITIONS HEADING THROUGH THE WEEKEND. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL NEAR TERM...CBL SHORT TERM...HARTFIELD LONG TERM...VINCENT FIRE WEATHER...BADGETT nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 311 AM CST SAT DEC 6 2008 .SHORT TERM...THROUGH MONDAY MUCH OF THE CONCERN IN THE SHORT TERM LIES IN TWO AREAS....TODAY/S WINDS AND COLD WITH FLURRIES AND BLOWING SNOW...AND SUNDAY AFTN/NIGHT SNOW AMOUNTS. FORECAST CONFIDENCE THROUGH THE SHORT TERM REMAINS RELATIVELY HIGH THANKS TO SOLID SHORT TERM MODEL AGREEMENT BEFORE THINGS RAPIDLY DETERIORATE INTO MONDAY/MONDAY NIGHT. CURRENTLY...POTENT FAMILY OF SHORTWAVES MOVING THROUGH WI/MN IN LEFT EXIT REGION OF 160KT JETLET DIGGING DOWN THE BACKSIDE OF IMPRESSIVE WRN CONUS RIDGING. THIS HAS DRIVEN A LARGE AREA OF LGT/MOD SNOWS ACROSS THE AREA OVERNIGHT WITH WIDESPREAD 1-2 INCH AMOUNTS AND POSSIBLY A LITTLE MORE ALONG/EAST OF MS RIVER. IN WAKE OF DEEP LIFT/STEADY SNOW...SOME -FZDZ/SNOW GRAIN MIXTURE HAS DEVELOPED BETWEEN TC METRO AND KLSE WITH MANY OBS HAVING UNKNOWN PRECIP AND LOOK OUTSIDE THE OFFICE CONFIRMS A SKOSH OF FZDZ IN THE NARROW WARM SECTOR SOUTH/WEST OF THE LOW AS IT MOVES THROUGH WITH RUC SOUNDINGS SUGGESTING TOP OF LOW CLOUD DECK RIGHT AT -8C TO -10C...WHICH SUPPORTS THE MIX OF FZDZ/SNOW GRAINS. 1002MB SFC LOW NEAR KEAU ALSO HELPING TO FOCUS CONVERGENCE ACROSS THE MS RIVER INTO CNTL WISCONSIN. COLD TEMPS /AND GUARANTEED ICE ACTIVATION/ NOT TOO FAR ENOUGH WITH TEMPS PLUMMETING INTO THE LOW TEENS NOW IN CNTL MN WITH STRONG WINDS /25-30KTS/. NEXT SHORTWAVE OF CONCERN SEEN IN GOES WV LOOPS CRESTING WRN CONUS RIDGE OFF BC COAST. TODAY...COLD FRONT SWINGS THROUGH THE AREA AROUND SUNRISE OR A LITTLE EARLIER WHICH STARTS A TEMP FREEFALL AS 850MB TEMPS START DAY AT -10C AND END THE DAY AT -20C. SFC TEMPS WILL BE IN A STEADY FALL ALL DAY FROM THE MID/UPPER 20S AT DAYBREAK INTO THE LOW/MIDDLE TEENS BY SUNSET. WINDS A BIG CONCERN TODAY...AS LAPSE RATES REALLY STEEPEN IN THE STRONG COLD ADVECTION...SUPPORTING TRANSFER OF 30KT GUSTS TO THE SFC IN THE STRONG SUBSIDENCE/PRESSURE RISE BUBBLE ESPECIALLY THIS MORNING. WITH THE NEW 1-3 INCHES OF SNOW AREA-WIDE...AND THEN THE PERIOD OF TEMPS NEAR 30 AND FZDZ OVERNIGHT...THERE IS UNCERTAINTY HOW THE SNOW WILL BLOW AROUND TODAY. THINK WINDS WILL BE STRONG ENOUGH TO REALLY DRIFT IN OPEN AREAS...SO EXPANDED BLSN ACROSS ENTIRE AREA THROUGH EARLY AFTN WHEN WINDS BEGIN TO FALL BACK SOME. DON/T SEE VIS RESTRICTIONS FROM BLSN UPSTREAM...BUT ROADS MAY GET DICEY IN A FEW OPEN AREAS. PLENTY OF FLURRIES UPSTREAM IN THE THIN BKN-OVC STRATOCUMULUS FIELD...SO KEPT FLURRIES IN THE FORECAST...ALL AREAS SHOULD SEE FLAKES FLYING FROM TIME TO TIME. A LITTLE CONCERN GIVEN THE LAPSE RATES THAT A FEW MORE VIGOROUS SHSN MAY DEVELOP...AND THIS WILL NEED TO BE WATCHED. WIND CHILLS BY LATE AFTERNOON DIP BELOW ZERO...WILL BE QUITE UNCOMFORTABLE OUTDOORS TODAY. TONIGHT...RIDGING/HIGH PRESSURE BRINGS CLEARING SKIES FOR A BRIEF PERIOD BEFORE MID/HIGH CLOUDS AHEAD OF NEXT WAVE SPREAD IN FROM WEST TO EAST LATE IN THE NIGHT. SHOULD BE ENOUGH TIME GIVEN FRESH SNOW AND CLEAR SKIES AND RAPIDLY DECOUPLING BOUNDARY LAYER TO DROP TEMPS NEAR/BELOW ZERO MOST AREAS...AND KEPT PREVIOUS TEMPS INTACT. SUNDAY/SUNDAY NIGHT...STILL FEEL GOOD ABOUT LIGHT SNOW ACCUMULATION EVENT SPREADING IN FROM WEST TO EAST DURING SUN AFTN INTO SUN NIGHT. DRIVEN LARGELY BY DEEP LAYER ISENTROPIC ASCENT /WARM ADVECTION/ AND STRONG LOW/MID LEVEL QG WITH AN OVERALL WEAK PV STRUCTURE. WIND VECTORS ON THE THETA SFCS ALMOST PERFECTLY ORTHOGONAL TO THE PRESSURE SFCS SUGGESTING OPTIMUM UPGLIDE AND GOOD OMEGA..CONFIRMED IN CROSS SECTIONS AND BUFR SOUNDINGS THROUGH THE EVENT. WHILE OVERALL SYSTEM MUCH WEAKER THAN CURRENT...WILL MAKE UP FOR IT IN GOOD SNOWFALL RATIOS /AT START OF EVENT/ AND BETTER MOISTURE ON 280-290K LAYER /SPEC HUMIDITY/. ANOTHER 1-2 INCHES LOOKS LIKELY...WITH 3 INCHES PROBABLY AN OUTLIER BUT POSSIBLE ESPECIALLY WEST OF RIVER WITH LIFT WEAKENING AS IT MOVES EAST/SOUTHEAST ACROSS THE AREA. A MORE RECENT DEVELOPMENT HERE ON SUNDAY NIGHT AS RAPID EROSION OF ICE-BEARING CLOUD IN LATE EVENING/OVERNIGHT WITH BOTH DETERMINISTIC RUNS OF GFS/NAM BUFR SOUNDINGS SHOWING A VERY DEEP LOW LEVEL /SFC-2.5KM/ SATURATED LAYER UNDERNEATH THE DRY AIR ALOFT. STRONG WARM ADVECTION STILL OCCURRING IN THIS LAYER BUT OMEGA IS WEAK. HINTS OF CONVERGENCE AXIS /WARM FRONT/ MOVING THROUGH AT THIS TIME SO SNOW COULD DEFINITELY END AS A PERIOD OF FREEZING DRIZZLE SUNDAY NIGHT SO ADDED THIS POTENTIAL TO FORECAST. BOTH MODELS ALSO PAINTING TELL- TALE SPECKLES OF VERY LIGHT QPF /DRIZZLE SIGNAL/ ON THE FORECAST AREA AFTER MIDNIGHT SO THIS TOO NEEDS TO BE WATCHED. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY CONFIDENCE STILL WELL BELOW AVG IN THIS TIME PERIOD. STILL SEEING HUGE DISCREPANCIES IN NUMEROUS AREAS...FIRST WITH HOW MON NIGHT/TUES WAVES PHASE /OR NOT PHASE/ AND THEN HOW MUCH ARCTIC AIR IS AROUND FOR WED/THUR/FRI. STILL SEEING VERY LARGE SPREAD IN BOTH LOW RESOLUTION ENSEMBLE MEMBERS...AND HIGHER RESOLUTION DETERMINISTIC RUNS WITH 850MB TEMPS ABOUT 15C TO 20C DIFFERENT FOR WED/THUR BETWEEN GFS AND ECMWF. NO WONDER CONFIDENCE PLOTS BASICALLY SUGGESTING ENSEMBLE DATA USELESS IN THIS DEGREE OF SPREAD/UNCERTAINTY. THE BIG FOCUS WILL BE ON MON NIGHT/TUES CNTL CONUS STORM WHICH HAS SHOWN A TREND IN ALL DETERMINISTIC RUNS TO SHIFT NORTHWARD GIVEN VARYING DEGREES OF PHASING OF THE NRN/SRN STREAMS ACROSS THE CNTL CONUS. THE NEW 06.00Z ECMWF /PROVEN SUPERIOR IN THIS TIME FRAME TO NCEP MODELS/ HAS TRENDED TOWARD A BONAFIDE HEAVY SNOW EVENT FOR MUCH OF IOWA INTO SRN WISCONSIN. THERE IS LESSER SUPPORT...BUT SUPPORT NONETHELESS FROM THE 06.00Z NAM-WRF AND CAN GEM...BUT 06.00Z GFS AND GEFS PROBABILITIES ARE WELL SOUTH. GIVEN THE UNCERTAINTY...TOOK BABY STEPS FOR THE TIME BEING AND BUMPED UP SNOW CHANCES ALL AREAS...ESP SOUTH TO 50S/60S WITH NOTION THESE MAY NEED TO GO SIGNIFICANTLY HIGHER WITH ONE MORE BATCH OF SUPPORTING RUNS FROM ECMWF/GEM/WRF. THERE/S EVEN A HINT AT A START OF RAIN/FZRA IN THE SOUTH MONDAY NIGHT...BUT NEED TO SEE MORE SUPPORT FOR THIS BEFORE PUTTING IN FORECAST. BOTTOM LINE...IF ECMWF TRENDS PROVE CORRECT...THIS STORM HAS CAPABILITY FOR SIGNIFICANT ACCUMULATIONS...AND WILL BEAR CLOSE WATCHING. FURTHER UNCERTAINTIES WITH THE SHORTWAVE /NRN STREAM/ SET TO RUN ACROSS THE NRN CONUS WED/WED NIGHT. MADE NO CHANGES HERE...AND THIS WAVE HAS HUGE IMPLICATIONS FOR TEMPERATURES /THUS THE HUGE SPREAD CURRENTLY SEEN IN ENSEMBLE/DETERMINISTIC RUNS/. PLENTY MORE ENERGY TO BE HAD IN THIS PATTERN TOWARD END OF WEEK INTO THE WEEKEND...CERTAINLY WILL BE ACTIVE/INTERESTING WITH BOATLOADS OF ARCTIC AIR CONTINUING TO BUILD IN CANADA AS LONGWAVE TROUGH SHIFTS TO WEST CONUS BY NEXT WEEKEND. && .AVIATION...TODAY INTO SUNDAY SHORTWAVE RESPONSIBLE FOR THE -SN AND PATCHY -FZDZ WILL EXIT QUICKLY EARLY THIS MORNING WITH THE PRECIP COMING TO AN END BEFORE 12Z. HOWEVER...AN EXPANSIVE MVFR STRATO-CU DECK EXTENDS UPSTREAM ACROSS MN/EASTERN DAKOTAS BEHIND IT. BRISK NORTHWEST WINDS BEHIND THIS SYSTEM WILL SPREAD ACROSS THE AREA FOR MUCH OF THE DAY...CREATING SOME BLOWING/DRIFTING OF THE NEW SNOW THRU THIS MORNING. THESE WINDS AND STRONG SUBSIDENCE IN THE WAKE OF THE LOW/FRONT AND SHORTWAVE CREATING SOME BREAKS IN THE MVFR CLOUD DECK ACROSS WESTERN MN. THESE BREAKS RATHER PATCHY AND TRANSITORY AND BKN/OVC MVFR CLOUDS EXPECTED TO DOMINATE THRU THE DAY. SFC TO 850MB RIDGE AXIS SLIDES ACROSS THE REGION FOR TONIGHT. LOWER LEVEL DIVERGENCE IN THE RIDGE AXIS AND SHALLOWER MOISTURE/DRIER AIR MOVING IN SHOULD ALLOW THE LOWER CLOUD DECK TO BREAK UP/SCATTER OUT FOR TONIGHT. VFR CONDITIONS EXPECTED THRU SUN MORNING WITH CLOUDS INCREASING AND -SN MOVING BACK INTO THE TAF SITES BY LATER SUN AFTERNOON. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM...BINAU AVIATION...RRS wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1015 AM EST SAT DEC 6 2008 .SYNOPSIS... HIGH PRESSURE WILL DRIFT ACROSS THE AREA TODAY, THEN RECEDE EAST AND WEAKEN. PRIMARY LOW PRESSURE WILL MOVE ACROSS THE GREAT LAKES REGION TONIGHT AND THEN BEGIN TO WEAKEN, WHILE SECONDARY LOW PRESSURE DEVELOPS OFF THE CAROLINA COAST, LIFTS NORTHEAST TOWARD THE CANADIAN MARITIMES AND DEEPENS SHARPLY. BY LATE SUNDAY, DEEP LOW PRESSURE OVER THE CANADIAN MARITIMES WILL PULL A RUSH OF ARCTIC AIR INTO OUR REGION. HIGH PRESSURE WILL BUILD OVER THE REGION MONDAY. A COLD FRONT IS EXPECTED TO CROSS THE REGION WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... HAVE MADE A FEW ADJUSTMENTS TO THE MORNING FCST PACKAGE. FIRST, HAVE INCREASED POPS A BIT OVER THE WHOLE AREA. THE LATEST RUC HAS SOME PRECIP REACHING THE ERN SHORE OF MD AND DELMARVA BY 00Z. THERE IS ALSO SOME WEAK ISENTROPIC LIFT. HOWEVER, THE NAM/WRF AND THE STAT GUIDANCE IS STILL VERY DRY. LATEST OBS HAVE DEW POINTS STILL IN THE TEENS, SO THE AMS REMAINS VERY DRY. SO, A SLIGHT INCREASE SEEMS REASONABLE FOR LATE AFTERNOON AND EARLY EVENING, WANTED TO TAKE THE PRUDENT COURSE AND NOT INCREASE THINGS TOO MUCH. OTHERWISE, HAVE ALSO INCREASED CLOUDS A BIT OVER THE AREA BASED ON LATEST SATELLITE TRENDS. MOST OF THE CURRENT CLOUDINESS IS CIRRUS, BUT CLOUDS SHOULD BEGIN TO LOWER AND THICKEN WITH TIME. WINDS SHOULD BE PRETTY LIGHT FOR MUCH OF THE DAY AS SURFACE HIGH PRESSURE MOVES BY US, BUT EVENTUALLY THEY SHOULD DEVELOP A SOUTHERLY COMPONENT WITH THE WEAKENING HIGH TO OUR EAST AND THE LOW TO OUR WEST. FORECAST TEMPERATURES ARE A BLEND OF CONTINUITY AND GUIDANCE. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... TONIGHT, THE APPROACHING MID LEVEL TROUGH WILL SHARPEN AS A JET STREAK, WHICH WAS DROPPING OUT OF CANADA EARLY THIS MORNING, DIGS AROUND THE TROUGH`S WESTERN SIDE, BOTTOMS OUT AND BEGINS TO LIFT AROUND THE EASTERN SIDE. THE SURFACE LOW MOVING THROUGH THE GREAT LAKES WILL NOT BENEFIT FROM THIS, BUT THE SECONDARY LOW OFF THE EASTERN SEABOARD WILL BEGIN TO DEEPEN. MODELS ARE IN FAIR AGREEMENT THROUGH 12Z SUNDAY WITH SOME PIVA, ALTHOUGH THE BRUNT OF THAT SEEMS FOCUSED FURTHER SOUTH. THEY ALSO AGREE ON THE BEGINNINGS OF SOME MID TO UPPER LEVEL Q-VECTOR CONVERGENCE AND SOME APPROACHING LOWER LEVEL FRONTOGENESIS, BUT THAT SEEMS TO COME TOGETHER AROUND 12Z. THEY DO PAINT SOME ISENTROPIC LIFT AT THE AFOREMENTIONED LEVEL LIFTING THROUGH OVERNIGHT. MODEL QPF EXISTS, BUT IS UNDER ONE-TENTH OF AN INCH AS THE BULK OF THE ACTION IS FORECAST WITH THE SECONDARY LOW. THIS DOESN`T SEEM LIKE A SCENARIO IN WHICH STAT GUIDANCE WOULD BE WOEFULLY UNDERDONE, AND WE CANNOT FIND ANY POPS FROM ANY PACKAGE IN OUR FORECAST AREA THAT EXCEEDS THE CHANCE LEVEL. WE WERE CARRYING HIGH LIKELY TO CATEGORICAL POPS, AND WE`VE BACKED OFF TO LOW LIKELY. OUR TEMPERATURES MAINTAIN CONTINUITY, AND BETWEEN THEM AND MODEL SOUNDINGS WE CARRY PRECIPITATION TYPES OF SNOW IN THE NORTHWEST AND A CHANGING MIXED BAG FURTHER SOUTH. ACCUMULATIONS IN THE NORTHWEST ARE NOT, AT PRESENT, THOUGHT TO AMOUNT TO MUCH. AFTER THAT, THINGS MAY GET INTERESTING. THE DEEPENING SECONDARY LOW COULD BECOME A BOMB AS IT LIFTS TOWARD THE CANADIAN MARITIMES DURING THE DAY ON SUNDAY. THE WARMTH AND MOISTURE THAT IT THROWS INTO THE EASTERN SIDE OF THE MID LEVEL TROUGH AND THE DECENT JET LIFTING UP SAME SIDE OF SAID TROUGH HAVE CONSISTENTLY BEEN FORECAST BY THE ECMWF, GFS AND NAM TO CAUSE IT TO DEVELOP A NEGATIVE TILT AS IT SWEEPS ACROSS US. ALL THREE MODELS HAVE A VERY NICE VORTICITY MAX MOVING ACROSS US WITH THE TROUGH AXIS. GFS H925 AND H8 WINDS ARE IN THE 40 TO 50 KT RANGE BY LATE SUNDAY, AND THE ECMWF WINDS ARE AT LEAST AS STRONG. THEIR TRAJECTORY IS OFF THE EASTERN GREAT LAKES, AND THE H8 TEMPERATURES OVER US BY 00Z MONDAY ARE EASILY BELOW -10 DEG C. THEY`RE EASILY BELOW -15 DEG C OVER THE EASTERN LAKES. MODEL SOUNDINGS IN THE WAKE OF THE SURFACE FRONTAL PASSAGE, WHICH HAPPENS AROUND OR A BIT BEFORE DAYBREAK, ARE DRY ADIABATIC THROUGH H8, AND THE SUBSIDENCE CAP IN THE COLD AIR IS UP AT AROUND 9K FT FOR THE FIRST HALF OF THE DAY. THE SURFACE FLOW IS CYCLONIC. THE WINDEX SCHEME THAT WE USE OFF THE OLD NGM FOUS DATA SUGGESTS THAT SNOW SQUALLS ARE A POSSIBILITY AT PHL. MEANWHILE, STAT GUIDANCE POPS ARE SLIGHT CHANCE AT BEST, AND THE HIGHEST ONES ARE FROM THE FWC GUIDANCE. REGARDING POPS, WE`VE DECIDED THAT THE PIVA, THE TRAJECTORY OF THE LOWER LEVEL WINDS, THE MORNING FRONTOGENESIS AND Q-VECTOR CONVERGENCE, THE CYCLONIC SURFACE FLOW, THE INITIALLY HIGH SUBSIDENCE CAPS AND THE INDICATIONS OF THE WINDEX TECHNIQUE ARE WORTH UPPING POPS TO HIGH CHANCE OVER THE NORTHWEST, MODERATE CHANCE AROUND THE I-95 CORRIDOR AND LOW END OF CHANCE SOUTHEAST OF THERE. WE ARE GOING FOR SNOW SHOWERS OVER LAND AND MUCH OF THE WATER, AND WE`RE GOING TO MENTION THE CHANCE OF SOME SNOW SQUALLS FROM THE FALL LINE NORTHWEST. WE CARRY A SLIGHT CHANCE OF THEM AROUND THE I-95 CORRIDOR. WE WILL MENTION THE POSSIBILITY OF THESE IN THE HWO. IF THE MODELS ARE CORRECT, ANY SNOW SHOULD BE ON THE DECLINE SUNDAY AFTERNOON. REGARDING WINDS, WE ARE FORECASTING WIND ADVISORY CRITERION WINDS TO DEVELOP DURING THE DAY ON SUNDAY AND DIMINISH SLOWLY SUNDAY NIGHT INTO MONDAY. WE WILL NOT PUT UP AN ADVISORY AT THIS POINT, BUT AGAIN WILL MENTION THIS IN THE HWO. FOR SUNDAY NIGHT INTO THE FIRST PART OF MONDAY, THE TRAJECTORIES ABOVE THE SURFACE MADE US KEEP LINGERING FLURRIES IN THE FAR NORTHWESTERN ZONES FOR A TIME. OTHERWISE, WE ARE PRECIPITATION FREE. WINDS, AS NOTED ABOVE, WILL DIMINISH GRADUALLY. REGARDING TEMPERATURES ON SUNDAY, WE STAYED CLOSER TO CONTINUITY THAN TO GUIDANCE ON THE COLD AIR ADVECTION AND EXPECTED CLOUDS, AND WE HAVE TEMPERATURES FALLING IN THE AFTERNOON. SUNDAY NIGHT AND MONDAY ARE A COLD BLEND OF GUIDANCE AND CONTINUITY. WIND CHILLS ON SUNDAY NIGHT LOOK TO TANK, AND THEY WILL BE MENTIONED IN THE HWO. FOR NOW, THEY DO NOT SHOW IN THE TEXT PRODUCT BUT ARE IN THE MATRICES. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... FOR MONDAY NIGHT AND TUESDAY...THE COLD HIGH MOVES OFF THE COAST AND A RETURN FLOW OF WARM ADVECTION DEVELOPS WITH THE UPPER TROUGH REFORMING AND DIGGING TO OUR WEST. THIS MEANS THE THREAT OF MORE PCPN. FOLLOWING HPC PROGS, IT LOOKS LIKE IT WILL WARM UP ENOUGH SO THAT MOST ANY PCPN SHOULD FALL AS RAIN. WEDNESDAY...A COLD FRONT COMES THROUGH FROM THE WEST ALLOWING ANY PCPN TO BECOME SHOWERY. HOWEVER, WITH MORE COLD AIR, ANY PCPN SHOULD CHANGE TO SNOW SHOWERS. THURSDAY AND FRIDAY...THIS IS THE PERIOD WITH THE LEAST AMOUNT OF CONFIDENCE. ANOTHER FRONT SHOULD CROSS THE REGION, BUT THERE IS THE POSSIBILITY OF LOW PRESSURE FORMING ON THE FRONT AND MOVING ACROSS OR EAST OF THE REGION. IF THIS IS TRUE, THE TIMING AND TRACK OF THE LOW WILL DETERMINE IF WE GET AN EAST COAST STORM WITH SNOW IN PARTS OF THE AREA OR NOT. && .AVIATION /10Z SATURDAY THROUGH WEDNESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS WILL REMAIN THROUGH ALL, IF NOT MOST OF THE DAYLIGHT HOURS, COURTESY OF SURFACE HIGH PRESSURE AND A WEST-SOUTHWEST FLOW ALOFT. SOME CIRRUS HAS ALREADY BEGUN TO FORM AND CLOUDS WILL GRADUALLY THICKEN AND LOWER. DECENT ISENTROPIC LIFT WILL OCCUR AS THE LOW IN THE EASTERN GREAT LAKES INTERACTS WITH THE LOW DEVELOPING OFF THE EAST COAST. A QUASI-WARM FRONT IS CONTINUED ON THE MODELS TO LIFT SLOWLY THROUGH THE AREA TONIGHT. ALTHOUGH THE MOS STATISTICAL GUIDANCE CAPS PROBABILITIES IN THE CHANCE CATEGORY, THERE SHOULD BE MORE SUBSTANTIAL, ALBEIT LIGHT, PRECIPITATION AS THIS FEATURE LIFTS THROUGH THE AREA IN VIEW OF THE MODERATE UPWARD VERTICAL MOTION AND "JUST ENOUGH" MOISTURE. SO, CEILINGS AND VISIBILITIES ARE FORECAST TO DROP TO MARGINAL VFR TONIGHT. FOR THE PHILADELPHIA 30 HOUR TAF, CONDITIONS WERE IMPROVED TOWARD MORNING AS THE PRECIPITATION DIMINISHES TO PERHAPS SCATTERED SNOW SHOWERS. REGARDING PRECIPITATION TYPE, NORTHERN TAF SITES LOOK TO BE ALL SNOW. SOUTHERN TAF SITES, ON THE SOUTHERN SIDE OF THE 1300 METER 1000-850 HPA THICKNESS DEMARCATION, SHOULD BE WEIGHTED TOWARD RAIN. THE CENTRAL TAF SITES WILL LIKELY START OFF AS RAIN, OR A MIX OF RAIN AND SNOW, BEFORE CHANGING TO SNOW AS THE COLUMN COOLS FROM EVAPORATIVE EFFECTS AND DIURNAL TRENDS WHICH CAUSE SURFACE COOLING. LIGHT WINDS THIS MORNING UNDER THE HIGH WILL SHIFT AROUND TO SOUTH AT 5 TO 10 KNOTS BY LATE MORNING OR MIDDAY AS THE HIGH SHIFTS OFFSHORE. THEN, WINDS WILL SWITCH AROUND TO WEST-SOUTHWEST TOWARD SUNDAY MORNING IN THE WAKE OF THE FRONT. OUTLOOK... THE GREAT LAKES LOW AND THE COASTAL LOW WILL MERGE WELL OFF THE NEW ENGLAND COASTAL WATERS SUNDAY MORNING, AND THE RESULTANT INTENSIFICATION WILL CAUSE GUSTY WEST-NORTHWEST WINDS AND AN UNSTABLE FLOW REGIME OVER OUR AREA. THIS MAY CAUSE SCATTERED SNOW SHOWERS SUNDAY AFTERNOON, ALONG WITH STRONG AND VERY GUSTY WINDS, WHICH ARE VERY LIKELY TO NEGATIVELY IMPACT AIR TRAVEL SUNDAY AFTERNOON AND EVENING. HIGH PRESSURE WILL BUILD MONDAY BUT MOVE OFFSHORE MONDAY NIGHT. ANOTHER FRONT WILL HEAD IN FOR WEDNESDAY. && .MARINE... CONDITIONS WILL REMAIN BELOW ADVISORY OR WARNING CONDITIONS TODAY AND TONIGHT, BUT THEN LOOK ALIVE MATEY AS HIGH-END GALE CONDITIONS ARE EXPECTED BY SUNDAY AFTERNOON, CONTINUING INTO SUNDAY NIGHT. HIGH PRESSURE OVER THE AREA THIS MORNING WILL MOVE OFFSHORE THIS AFTERNOON. MARINE CONDITIONS SHOULD BE FINE, BUT COLD. RAIN AND SOME SNOW MOVING IN FOR TONIGHT WILL LOWER VISIBILITIES, BUT WINDS AND SEAS WILL REMAIN UNDER ADVISORY CRITERIA. LOW PRESSURE OVER THE EASTERN GREAT LAKES WILL MOVE EASTWARD TONIGHT AND MERGE WITH A LOW HEADING NORTHEASTWARD OFF THE EAST COAST. AS THEY MERGE SUNDAY, RAPID INTENSIFICATION WILL CAUSE A STRONG CIRCULATION OVER OUR AREA SUNDAY AFTERNOON AND NIGHT. WEST-NORTHWEST 925 HPA WINDS ARE FORECAST TO REACH 45 KNOTS, AND WITH MUCH COLDER AIR OVER RELATIVELY WARM WATER, DOWNWARD MOMENTUM TRANSFER SHOULD BE EXCELLENT. SO, THE INHERITED GALE WATCH WILL BE CHANGED TO A GALE WARNING, AND THE TIMES WILL BE ADJUSTED...BACKED UP TO 16Z SUNDAY FOR A START TIME, AND RUN THROUGH 11Z MONDAY. THE STRONG WEST-NORTHWEST FLOW WILL ALSO RESULT IN BELOW NORMAL TIDES. HOWEVER, AT THIS TIME IT DOES NOT APPEAR AS IF THEY WILL REACH THE BLOWOUT TIDE THRESHOLD, ACCORDING TO NGM AND AVIATION STORM SURGE GUIDANCE WHEN COUPLED WITH THE ASTRONOMICAL TIDES. HIGH PRESSURE WILL DOMINATE FOR MONDAY BUT MOVE OFFSHORE BY TUESDAY. THEN, ANOTHER FRONT IS FORECAST TO APPROACH TUESDAY NIGHT AND WEDNESDAY, PRECEDED BY STRONG SOUTHERLY WINDS. THIS WOULD BE A CASE OF WARMER AIR OVER COLDER WATER, SO THERE WOULD BE LESS MIXING OF MOMENTUM DOWN TO THE SURFACE. HOWEVER, SMALL CRAFT ADVISORY CONDITIONS ARE POSSIBLE WITH THIS SYSTEM AROUND THE MIDDLE OF NEXT WEEK. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...GALE WARNING FROM 9 AM SUNDAY TO 6 AM EST MONDAY FOR ANZ430- 431-450>455. && $$ SYNOPSIS...DELISI NEAR TERM...NIERENBERG/DELISI SHORT TERM...DELISI LONG TERM...STAUBER AVIATION...NIERENBERG MARINE... de AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 1049 AM EST SAT DEC 6 2008 .SYNOPSIS... A WAVE OF LOW PRESSURE WILL MOVE UP THE COAST TODAY THEN A REINFORCING COLD FRONT WILL CROSS THE REGION TONIGHT. DRY HIGH PRESSURE WILL BUILD IN SUNDAY THROUGH MONDAY. A COASTAL TROUGH WILL DEVELOP MONDAY NIGHT AND TUESDAY...THEN A COMPLEX STORM SYSTEM WILL AFFECT THE SOUTHEAST REGION DURING THE LATTER HALF OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THERE HAS DEFINITELY BEEN A PRONOUNCED WESTWARD SHIFT IN MOST MODELS WITH THE UPPER SHORTWAVE AND SURFACE TROUGH EXPECTED TO MOVE THROUGH THE COASTAL WATERS LATE THIS AFTERNOON. LOW-LEVEL MOISTURE HAS ALREADY BEGUN TO POOL AHEAD OF THE SHORTWAVE NOW LOCATED ALONG THE GULF COAST STATES WITH SFC DEWPOINTS INCREASING INTO THE MID 40S ALONG THE COAST. LIGHT RAIN WILL LIKELY BEGIN TO DEVELOP BY EARLY AFTERNOON ACROSS SOUTHEAST GEORGIA AND THE COASTAL WATERS. CONFIDENCE QUICKLY DECREASES WHEN ASSESSING POTENTIAL FOR RAIN ACROSS SOUTHEAST SOUTH CAROLINA. IF ANY RAIN OCCURS...IT WILL LIKELY BE AFTER 3 PM AND ACROSS COASTAL COUNTIES. THE 4 KM WRF SHOWS A FEW HOURS OF LIGHT RAIN LATE THIS AFTERNOON THROUGH THE EVENING IN COASTAL SC ALTHOUGH THE 12Z NAM-12 KEEPS ALL RAIN JUST OFFSHORE. THE GFS BRINGS RAIN TO COASTAL LAND AREAS...AS WELL AS THE 00Z ECMWF...ALTHOUGH THE RUC-13 IS DRIER. BASED ON THE CURRENT POSITION OF THE SHORTWAVE AND A BAROCLINIC LEAF APPEARING OFF THE GA COAST ON VIS SATELLITE...A FEW HOURS OF SCATTERED LIGHT RAIN SHOWERS WILL BE POSSIBLE ACROSS ABOUT TWO TIERS OF GA COASTAL COUNTIES AND MAYBE ONE LAYER OF COUNTIES ALONG THE SC COAST. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... THE LAST OF THE MAINLY LIGHT STRATIFORM RNFL WILL EXIT THE CENTRAL SOUTH CAROLINA COAST PRIOR TO MIDNIGHT WITH SKIES CLEARING AND WINDS STIRRING FROM THE NW TO W WITH THE ARRIVAL OF A MODIFIED CONTINENTAL POLAR AIR AIR MASS. SKIES WILL CLEAR ALL AREAS BEFORE DAWN ON SUNDAY AS THE UPPER TROF AXIS PASSES. WE HAVE CONTINUED TO FAVOR THE COOLER GFS MOS LOW TEMPERATURE SCHEME WHICH FITS IN REAL NICE WITH OUR FORECAST PERSISTENCE. && .LONG TERM /SUNDAY THROUGH FRIDAY/... MUCH UNCERTAINTY CONTINUES TO PLAGUE THE EXTENDED PERIODS THIS MORNING...BUT OVERALL THE MODELS AGREE THAT A FAIRLY UNSETTLED PERIOD CAN BE EXPECTED FROM MID TO LATE WEEK. GUIDANCE IS IN GOOD AGREEMENT THAT HIGH PRESSURE WILL BUILD NORTH OF THE REGION SUNDAY THROUGH MONDAY...AND WILL KEEP THE FORECAST RAIN FREE. THE RIDGE OF HIGH PRESSURE IS EXPECTED TO SLIDE EASTWARD AND INTO THE ATLANTIC MONDAY NIGHT THROUGH TUESDAY NIGHT. AS HIGH PRESSURE SHIFTS OFFSHORE...A COASTAL TROUGH WILL DEVELOP OFF THE SOUTH CAROLINA AND GEORGIA COAST MONDAY NIGHT AS SUGGESTED BY MOST OPERATIONAL GUIDANCE...WITH THE TROUGH SHIFTING NORTH OF THE AREA BY LATE IN THE DAY TUESDAY. WILL CONTINUE TO CARRY SLIGHT CHANCE/CHANCE POPS MONDAY NIGHT AND TUESDAY FOR PRIMARILY COASTAL ZONES...WITH A BIT FURTHER WESTWARD EXTENT INTO INTERIOR SOUTH CAROLINA ZONES GIVEN SOUTH-SOUTHEASTERLY LOW LEVEL STEERING FLOW OFF THE ATLANTIC. MAIN FORECAST CONCERN IN THE EXTENDED PERIODS REVOLVES AROUND THE HANDLING OF THE MID TO LATE WEEK STORM SYSTEM EXPECTED TO IMPACT THE FORECAST AREA. BOTH THE GFS AND ECMWF HAVE REMAINED FAIRLY CONSISTENT FROM ONE RUN TO THE NEXT. IT DOES APPEAR HOWEVER THAT THEY ARE BOTH BEGINNING TO CONVERGE ON A COMMON SOLUTION...BUT THIS WILL LIKELY TAKE SEVERAL MORE RUNS BEFORE A COMMON SOLUTION BECOMES CLEARLY APPARENT. THE GFS PUSHES A FRONT THROUGH THE AREA WEDNESDAY...THEN DEVELOPS A WAVE ALONG THE FRONT WEDNESDAY NIGHT AND LIFTS IT NORTHEASTWARD OFF THE SOUTH CAROLINA AND GEORGIA COAST ON THURSDAY. THE ECMWF ON THE OTHER HAND PUSHES A COLD FRONT THROUGH THE AREA ON THURSDAY...THEN LIFTS THE FRONT BACK NORTHWARD LATE THURSDAY NIGHT AS A WAVE OF LOW PRESSURE MOVES NORTHWARD OUT OF THE GULF OF MEXICO AND ACROSS THE FORECAST AREA ON FRIDAY. THE CANADIAN IS MORE SIMILAR TO THE GFS AND THE UKMET MORE SIMILAR TO THE ECMWF. GFS ENSEMBLE MEMBERS CONTINUE TO FAVOR A FASTER AND MORE PROGRESSIVE SOLUTION...WHICH AIDS IN FORECAST UNCERTAINTY CONSIDERING MOST OF THE OPERATIONAL GUIDANCE IS SLOWING THE SYSTEMS PROGRESSION DOWN. EXPECT THAT THE MOST PROBABLE SOLUTION LIES SOMEWHERE IN BETWEEN THE GFS AND ECMWF SOLUTIONS SO WILL TRY TO INCORPORATE IDEAS FROM EACH WITH THE MORNING PACKAGE TO REDUCE POTENTIAL FORECASTS BUSTS IN THE LATTER PERIODS AS THEY COULD BE QUITE LARGE. TO MAKE A LONG STORY SHORT...IT LOOKS LIKE A FAIRLY UNSETTLED PERIOD WEDNESDAY THROUGH FRIDAY...AND WILL CARRY CHANCE POPS THROUGHOUT. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... AT KCHS...SKIES HAVE RECENTLY CLEARED OUT AND FOG WAS ATTEMPTING TO DEVELOP ONCE AGAIN. HIGHER LEVEL CLOUDS WERE SLOWING DOWN THE PROCESS. WE START THE MORNING OFF WITH MVFR VSBYS AND SCATTERED STRATUS AND STRATOCUMULUS. KSAV APPEARS TO HAVE THICKER HIGH LEVEL CLOUDS STREAMING OVHD AND WE HAVE ONLY HAVE A TEMPO FOR MVFR VSBYS TO INITIALIZE THE 12Z CYCLE. ANOTHER UPPER LEVEL DISTURBANCE CROSSES FLORIDA THIS MORNING AND MOVES OFF THE CAROLINA COAST BY THIS EVENING. WILL NEED TO WATCH FOR MVFR CIGS AND VSBYS FOR A WHILE MID TO LATE AFTERNOON WHILE SOME LIGHT RAIN PASSES ALONG THE COAST. THERE MAY BE A VERY BRIEF WINDOW FOR FOG OR IFR CIGS AGAIN THIS EVENING BEFORE CONDITIONS IMPROVE QUICKLY TO VFR AT BOTH TERMINALS TOWARD 070300-070600. EXTENDED AVIATION OUTLOOK...VFR CONDITIONS ARE EXPECTED SUNDAY THROUGH MONDAY. MVFR OR LOWER CONDITIONS ARE POSSIBLE AT THE TERMINALS MONDAY NIGHT THROUGH WEDNESDAY AS A COMPLEX STORM SYSTEM IMPACTS THE AREA. && .MARINE... A FAIRLY WEAK PRES PATTERN WILL KEEP RELATIVELY TRANQUIL MARINE CONDITIONS GOING FOR MOST OF TODAY. A COLD FRONT WILL MOVE THROUGH THE WATERS LATE THIS AFTERNOON...FOLLOWED BY A COOLER AND DRIER AIR AIR MASS PUNCHING IN TONIGHT. INCREASING W FLOW SHOULD JET OFF THE COAST AND WE HAVE ISSUED A SECOND PERIOD SMALL CRAFT ADVISORY FOR OUR 20-60 NM GEORGIA WATERS. AS USUAL...WE WILL NEED TO WATCH CONDITIONS AT GRAYS REEF FOR A PERIOD OF WINDS TOUCHING ADVISORY CRITERIA. OFFSHORE FLOW TONIGHT WILL BUILD SEAS TO 2-4 FT WITHING 20 NM...BUT HIGHER 4-6 FT SEAS ARE LIKELY AFTER MIDNIGHT BEYOND 30 NM E OF THE GEORGIA COAST. HIGH PRESSURE WILL BUILD NORTH OF THE REGION SUNDAY THROUGH MONDAY...THEN SHIFT OFFSHORE AND INTO THE ATLANTIC TUESDAY AND TUESDAY NIGHT. A COLD FRONT WILL APPROACH FROM THE WEST ON WEDNESDAY. SMALL CRAFT CONDITIONS ARE EXPECTED TO CONTINUE ACROSS THE OUTER GEORGIA WATERS SUNDAY MORNING. OTHERWISE WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT THRESHOLDS SUNDAY THROUGH MONDAY. THE COMBINATION OF PERSISTENT EASTERLY FLOW AND BUILDING SWELL MAY RESULT IN A NEED FOR SMALL CRAFT ADVISORIES ACROSS PORTIONS OF THE WATERS ONCE AGAIN MONDAY NIGHT THROUGH WEDNESDAY. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 12 PM EST SUNDAY FOR AMZ374. && $$ JRL ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 932 AM EST SAT DEC 6 2008 .UPDATE... AREA OF SNOW MOVG ACROSS CWA ATTM. SNOW FALLING IN WAA REGIME AHEAD OF LOW MOVG SE ACROSS NRN LM. WRN EDGE OF AREA OF PRECIP JUST AHEAD OF THE SYSTEMS COLD FRONT... LOOSES MID LEVEL MOISTURE RESULTING IN SOME FREEZING DRIZZLE...HAVE ADDED MENTION OF PATCHY FREEZING DRIZZLE TO SE 2/3 OF CWA AS FRONT MOVES THROUGH TODAY. UPSTREAM TEMPS AND CONTD WAA AHEAD OF FRONT SUGGEST GOING HIGHS FOR TODAY ARE A BIT ON THE COLD SIDE AND GENERALLY RAISED ABOUT 3F. OTRWS NO SGFNT CHANGES MADE ATTM. && .PREV DISCUSSION... /ISSUED 620 AM EST SAT DEC 6 2008/ AVIATION... SNOW WILL BE OVER THE AREA THIS MORNING AND DIMINISH BY AFTERNOON. VIS RESTRICTIONS AND LOWER CIGS EXPECTED. LAKE EFFECT SNOW SHOWERS WILL DEVELOP THIS AFTERNOON AND CONTINUE INTO SUNDAY. THIS WILL AFFECT MAINLY KSBN BUT TRAJECTORIES SUGGEST SOME SNOW SHOWERS COULD MAKE IT INTO KFWA. SHORT TERM... ..WINTER WEATHER TO IMPACT THE REGION TODAY AND TONIGHT... TODAY THROUGH SUNDAY NIGHT RATHER POTENT SHORTWAVE TROUGH AND ASSOCIATED SFC CYCLONE IS PUSHING INTO THE GREAT LAKES REGION. AN AREA ON LIGHT TO MODERATE SNOW IS ONGOING OVER PORTIONS OF IL/IN/WI IN THE WARM CONVEYOR BELT PORTION OF THE SYSTEM...WHERE A 50 KNOT LL JET IS AIDING IN WEAK MOISTURE ADVECTION AND CROSS ISOBARIC FLOW...LENDING TO UPGLIDE. VERY DRY COLUMN AS INDICATED BY ILX AND DVN SOUNDINGS IS ACTING TO LIMIT SNOWFALL SOMEWHAT...SUPPORTING WIDESPREAD VIRGA UNTIL SATURATION IS REACHED. THIS IS EVIDENT IN THE DONUT HOLE SIGNATURES THAT WERE OBSERVED AT DVN/ILX/AND LOT. REGARDLESS...ONCE SATURATION IS REACHED...EXPECTING A PERIOD OF LIGHT TO MODERATE SNOW TO OVERSPREAD THE REGION...SUPPORTING A QUICK BURST OF 1 TO 2 INCHES OF SNOW...WITH 1 INCH AMOUNTS MORE THE NORM. RATHER ROBUST TROPOPAUSE PRESSURE RISES COUPLED WITH STEEP MID LEVEL LAPSE RATES AND DECENT MOISTURE CONVERGENCE WILL CONTINUE TO SO SUPPORT BROAD LIFT THROUGH MUCH OF THE MORNING AND ACROSS THE FA. HAVE FAVORED THE SREF AND GFS WRT QPF GUIDANCE WITH THE CLIPPER SYSTEM...BUT OPTED FOR THE SUPPORT OF THE NAM12 FOR LAKE EFFECT PROCESSES. ALSO UTILIZED THE RUC13 FOR ADDED GUIDANCE. TODAY...CLIPPER SYSTEM WILL QUICKLY LEAVE GENERALLY 1 INCH OF SNOWFALL ACROSS THE MAJORITY OF THE FA. IN ADDITION STAUNCH FLOW/A RATHER TIGHT PRESSURE GRADIENT/STRONG FLOW ALOFT...45 TO 50 KNOTS OF H95 GEOSTROPHIC FLOW/AND LINKED MOMENTUM UNDER CAA WILL SUPPORT GUSTY WESTERLY WINDS. SUSTAINED WINDS OF 15 TO 25 MPH WITH HIGHER GUSTS ARE EXPECTED THROUGH THE EVENING. THIS WILL ALLOW FOR AREAS OF BLOWING AND DRIFTING SNOW...MAKING TRAVEL DIFFICULT IN SOME AREAS. ROBUST CAA WITH H85 T/S DROPPING 5 TO 6C WILL HELP SUPPORT INCREASED INSTABILITY OVER LK MI THIS AFTERNOON. WESTERLY FLOW AT FIRST WILL LIMIT LK SNOW SHOWERS TO MAINLY MI THIS AFTERNOON. LL FLOW WILL CONTINUE TO VEER BEHIND THE COLD FRONT...INCREASING THE FLOW FETCH OVER LK MI...WITH PRECONDITIONED FLOW FROM LAKE SUPERIOR DEVELOPING. A SECONDARY UPPER IMPULSE WILL ACT TO FURTHER INCREASE INVERSION HEIGHTS ALREADY MODIFIED BY LAKE AGGREGATE EFFECTS FROM LK SUPERIOR. THE NET EFFECT WILL BE LAKE INDUCED CAPES OF 500 TO 700 J/KG WITH MAX UPWARD OMEGA IN THE DGZ. THIS WILL FAVOR THE DEVELOPMENT OF SEVERAL INTENSE BANDS OF LK EFFECT SNOW...CONGEALING INTO ONE DOMINATE BAND AS CONVECTIVE INFLUENCES EVENTUALLY OUTWEIGH WIND SHEAR EFFECTS. NAM12 AND RUC 13 PROGS HAVE CONSISTENTLY BEEN SUPPORTING THE PLACEMENT OF THIS BAND OVER EASTERN BERRIEN AND CASS COUNTIES. HIRES WRF SIMULATIONS FURTHER SUPPORT THIS IDEA. SNOWFALL RATES OF 2 TO 4 INCHES PER HOUR ARE WILL BE POSSIBLE WITH AN INTENSE DOMINATE BAND...ESPECIALLY IF THE LL MASS FIELD READJUSTS TO THE MESOSCALE PROCESS...ENHANCING LL CONVERGENCE. HAVE ISSUED A WINTER STORM WARNING FOR BERRIEN AND CASS COUNTIES...WITH 1 TO 2 INCHES OF SNOWFALL THIS MORNING/PERIODS OF LAKE EFFECT SNOW THIS AFTERNOON WITH AND ADDITIONAL 2 TO 3 INCHES POSSIBLE/BLOWING SNOW THROUGH THE DAY AND NIGHT SIGNIFICANTLY REDUCING VISIBILITIES/AND ADDITIONAL HEAVY LAKE EFFECT SNOW WITH AN ADDITIONAL 4 TO 8 INCHES POSSIBLE. OPTED FOR A WINTER WEATHER ADV FOR ST. JOE IN/MI AND ELKHART FOR COMBINATION OF LAKE EFFECT SNOW AND BLOWING SNOW WITH 3 TO 6 INCHES POSSIBLE BY SUNDAY MORNING. IT IS QUITE POSSIBLE THAT LAGRANGE AND MAYBE NOBLE COUNTIES MAY HAVE TO BE ADDED TO THE ADV AS CURRENT MODEL GUIDANCE CERTAINLY HINTS AT A PERIOD OF INTENSE LL OMEGA CENTERED OVER THESE COUNTIES. HEAVIEST LAKE SNOWS WILL OCCUR SAT EVENING AND BEGIN TO DIMINISH SUN MORNING WITH FALLING INVERSION HEIGHTS AND SFC RIDGING SHIFTING WINDS TO THE SW. TEMPS WILL REMAIN COLD THROUGH THE PERIOD WITH HIGHS RAGING 10 TO 15 DEGREES BELOW NORMAL. HAVE OPTED TO UNDERCUT GUIDANCE TEMPS GIVEN ANOMALOUSLY COLD CONDITIONS PRESENT. LONG TERM... ..MONDAY THROUGH FRIDAY... COMPLICATED AND LOW CONFIDENCE LONG TERM FORECAST DUE TO HIGHLY ENERGETIC AND COMPLICATED MID AND UPPER LEVEL FLOW OVER PACIFIC AND WESTERN NORTH AMERICA. STILL EXPECT BELOW NORMAL TEMPERATURES FOR A LARGE PART OF THE PERIOD AND POTENTIAL FOR A MODERATE TO HEAVY PRECIPITATION EVENT MID WEEK. WATER VAPOR THIS MORNING SHOWS A VERY ENERGETIC PATTERN...SIMILAR TO LAST YEAR ABOUT THIS TIME. AS DISCUSSED LAST NIGHT...MODELS LIKELY NOT RESOLVING FEATURES OVER THE PACIFIC WELL GIVEN LIMITED SAMPLING MEASURES. FIRST AREA OF CONCERN IS WITH IMPRESSIVE LOOKING SUB-TROPICAL MOISTURE PLUME DEVELOPING NEAR 15N AND 120W. MODELS TRYING TO PICK UP ON THIS BUT CONCERNED THEY ARE NOT NEAR STRONG ENOUGH GIVEN DEPICTION IN WATER VAPOR. THIS AREA EXPECTED TO CONTINUE SPREADING NORTHEAST AND WILL FEED INTO DEVELOPING MID LEVEL LOW OFF OF CA COAST THAT WILL BECOME OUR WEATHER MAKER FOR MID WEEK. SECONDARY AREA OF CONCERN IS WITH STRONG JET CORE NEAR 40N AND 150W. MODELS DO SEEM TO HAVE A HANDLE ON THIS FEATURE...BUT GIVEN ITS STRENGTH THERE IS SOME CONCERN WITH HOW IT WILL EVOLVE OVER WESTERN CONUS. THIS IS A LARGE PART OF THE DIFFERENCES IN MODEL SOLUTIONS FOR MID WEEK. IT WILL BE THE INTERACTION OF THESE TWO PACIFIC FEATURES WITH THE MID LEVEL LOW ACROSS THE SOUTHWEST CONUS THAT DETERMINES ITS EVOLUTION AND IMPACT ON OUR AREA. AS MENTIONED LAST NIGHT...WE FELT MODELS WERE NOT HANDLING THIS ENERGY WELL AND A STRONGER SYSTEM WAS EXPECTED. LATEST MEDIUM RANGE SOLUTIONS ARE INDEED STRONGER...WITH GFS BEING THE STRONGEST. COMPLICATIONS FOR OUR FORECAST AREA WILL BE WITH AMOUNT OF WARM AIR ADVECTION AHEAD OF SYSTEM AND ITS ACTUAL TRACK. ECMWF WHILE WEAKER IS FURTHER NORTH WITH STRONG WAA AND MOISTURE INFLUX INTO THE AREA LATE MONDAY NIGHT AND TUESDAY...INDICATING A POSSIBLE HEAVY RAIN EVENT. GFS IS STRONGER AND FURTHER SOUTH WITH COLDER AIR OVER NORTHERN HALF OF FORECAST AREA...YIELDING A POSSIBLE RAIN EVENT SOUTH AND SNOW NORTH. BOTH SOLUTIONS PLAUSIBLE AND AGAIN WILL LIKELY NOT BE RESOLVED UNTIL SYSTEM GETS WITHIN RADIOSONDE NETWORK. AGREEMENT LIES WITH SOME TYPE OF PRECIPITATION EVENT WITH POTENTIAL FOR HEAVY PCPN SOMEWHERE IN THE WESTERN LAKES OR OHIO VALLEY REGION FROM LATE MONDAY NIGHT INTO EARLY WEDNESDAY. HAVE INCREASED POPS DURING THIS WINDOW WITH LIKELY POPS CENTERED ON TUESDAY. STAYED WITH ALL SNOW MONDAY NIGHT WITH INITIAL COLDER AIR IN PLACE AND LOWER WET BULB TEMPERATURES. ALSO STAYED WITH RAIN OR SNOW MENTION TUESDAY GIVEN UNCERTAINTY IN TRACK AND THERMAL FIELDS. BEYOND WEDNESDAY FEW CHANGES WERE MADE. MODELS CONTINUE TO INDICATE SOME TYPE OF COLDER AIR INTRUSION BUT NOT NEAR AS STRONG AS 48 HOURS AGO. THUS KEPT IDEA OF SLIGHTLY BELOW NORMAL TEMPERATURES. CLIPPER SYSTEM POSSIBLE BY END OF WEEK BUT AGAIN QUITE A BIT OF DISAGREEMENT IN MODELS SO NO CHANGES MADE. SOME SIGNALS TO A PATTERN CHANGE WELL BEYOND DAY 7...TOWARD MID MONTH. ENSEMBLES SHOWING WESTERN CONUS RIDGE BEING REPLACED BY DEEP TROUGH WITH FLOW OVER OUR AREA BECOMING MORE SOUTHWEST AND POSSIBLY ACTIVE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 7 AM EST SUNDAY FOR INZ004-005. MI...WINTER STORM WARNING UNTIL 7 AM EST SUNDAY FOR MIZ077-078. WINTER WEATHER ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ079. OH...NONE. LM...GALE WARNING UNTIL 3 AM EST SUNDAY FOR LMZ043-046. && $$ SHORT TERM...JC LONG TERM...LASHLEY AVIATION...JC UPDATE...TAYLOR in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 620 AM EST SAT DEC 6 2008 .AVIATION... SNOW WILL BE OVER THE AREA THIS MORNING AND DIMINISH BY AFTERNOON. VIS RESTRICTIONS AND LOWER CIGS EXPECTED. LAKE EFFECT SNOW SHOWERS WILL DEVELOP THIS AFTERNOON AND CONTINUE INTO SUNDAY. THIS WILL AFFECT MAINLY KSBN BUT TRAJECTORIES SUGGEST SOME SNOW SHOWERS COULD MAKE IT INTO KFWA. && .SHORT TERM... ...WINTER WEATHER TO IMPACT THE REGION TODAY AND TONIGHT... TODAY THROUGH SUNDAY NIGHT RATHER POTENT SHORTWAVE TROUGH AND ASSOCIATED SFC CYCLONE IS PUSHING INTO THE GREAT LAKES REGION. AN AREA ON LIGHT TO MODERATE SNOW IS ONGOING OVER PORTIONS OF IL/IN/WI IN THE WARM CONVEYOR BELT PORTION OF THE SYSTEM...WHERE A 50 KNOT LL JET IS AIDING IN WEAK MOISTURE ADVECTION AND CROSS ISOBARIC FLOW...LENDING TO UPGLIDE. VERY DRY COLUMN AS INDICATED BY ILX AND DVN SOUNDINGS IS ACTING TO LIMIT SNOWFALL SOMEWHAT...SUPPORTING WIDESPREAD VIRGA UNTIL SATURATION IS REACHED. THIS IS EVIDENT IN THE DONUT HOLE SIGNATURES THAT WERE OBSERVED AT DVN/ILX/AND LOT. REGARDLESS...ONCE SATURATION IS REACHED...EXPECTING A PERIOD OF LIGHT TO MODERATE SNOW TO OVERSPREAD THE REGION...SUPPORTING A QUICK BURST OF 1 TO 2 INCHES OF SNOW...WITH 1 INCH AMOUNTS MORE THE NORM. RATHER ROBUST TROPOPAUSE PRESSURE RISES COUPLED WITH STEEP MID LEVEL LAPSE RATES AND DECENT MOISTURE CONVERGENCE WILL CONTINUE TO SO SUPPORT BROAD LIFT THROUGH MUCH OF THE MORNING AND ACROSS THE FA. HAVE FAVORED THE SREF AND GFS WRT QPF GUIDANCE WITH THE CLIPPER SYSTEM...BUT OPTED FOR THE SUPPORT OF THE NAM12 FOR LAKE EFFECT PROCESSES. ALSO UTILIZED THE RUC13 FOR ADDED GUIDANCE. TODAY...CLIPPER SYSTEM WILL QUICKLY LEAVE GENERALLY 1 INCH OF SNOWFALL ACROSS THE MAJORITY OF THE FA. IN ADDITION STAUNCH FLOW/A RATHER TIGHT PRESSURE GRADIENT/STRONG FLOW ALOFT...45 TO 50 KNOTS OF H95 GEOSTROPHIC FLOW/AND LINKED MOMENTUM UNDER CAA WILL SUPPORT GUSTY WESTERLY WINDS. SUSTAINED WINDS OF 15 TO 25 MPH WITH HIGHER GUSTS ARE EXPECTED THROUGH THE EVENING. THIS WILL ALLOW FOR AREAS OF BLOWING AND DRIFTING SNOW...MAKING TRAVEL DIFFICULT IN SOME AREAS. ROBUST CAA WITH H85 T/S DROPPING 5 TO 6C WILL HELP SUPPORT INCREASED INSTABILITY OVER LK MI THIS AFTERNOON. WESTERLY FLOW AT FIRST WILL LIMIT LK SNOW SHOWERS TO MAINLY MI THIS AFTERNOON. LL FLOW WILL CONTINUE TO VEER BEHIND THE COLD FRONT...INCREASING THE FLOW FETCH OVER LK MI...WITH PRECONDITIONED FLOW FROM LAKE SUPERIOR DEVELOPING. A SECONDARY UPPER IMPULSE WILL ACT TO FURTHER INCREASE INVERSION HEIGHTS ALREADY MODIFIED BY LAKE AGGREGATE EFFECTS FROM LK SUPERIOR. THE NET EFFECT WILL BE LAKE INDUCED CAPES OF 500 TO 700 J/KG WITH MAX UPWARD OMEGA IN THE DGZ. THIS WILL FAVOR THE DEVELOPMENT OF SEVERAL INTENSE BANDS OF LK EFFECT SNOW...CONGEALING INTO ONE DOMINATE BAND AS CONVECTIVE INFLUENCES EVENTUALLY OUTWEIGH WIND SHEAR EFFECTS. NAM12 AND RUC 13 PROGS HAVE CONSISTENTLY BEEN SUPPORTING THE PLACEMENT OF THIS BAND OVER EASTERN BERRIEN AND CASS COUNTIES. HIRES WRF SIMULATIONS FURTHER SUPPORT THIS IDEA. SNOWFALL RATES OF 2 TO 4 INCHES PER HOUR ARE WILL BE POSSIBLE WITH AN INTENSE DOMINATE BAND...ESPECIALLY IF THE LL MASS FIELD READJUSTS TO THE MESOSCALE PROCESS...ENHANCING LL CONVERGENCE. HAVE ISSUED A WINTER STORM WARNING FOR BERRIEN AND CASS COUNTIES...WITH 1 TO 2 INCHES OF SNOWFALL THIS MORNING/PERIODS OF LAKE EFFECT SNOW THIS AFTERNOON WITH AND ADDITIONAL 2 TO 3 INCHES POSSIBLE/BLOWING SNOW THROUGH THE DAY AND NIGHT SIGNIFICANTLY REDUCING VISIBILITIES/AND ADDITIONAL HEAVY LAKE EFFECT SNOW WITH AN ADDITIONAL 4 TO 8 INCHES POSSIBLE. OPTED FOR A WINTER WEATHER ADV FOR ST. JOE IN/MI AND ELKHART FOR COMBINATION OF LAKE EFFECT SNOW AND BLOWING SNOW WITH 3 TO 6 INCHES POSSIBLE BY SUNDAY MORNING. IT IS QUITE POSSIBLE THAT LAGRANGE AND MAYBE NOBLE COUNTIES MAY HAVE TO BE ADDED TO THE ADV AS CURRENT MODEL GUIDANCE CERTAINLY HINTS AT A PERIOD OF INTENSE LL OMEGA CENTERED OVER THESE COUNTIES. HEAVIEST LAKE SNOWS WILL OCCUR SAT EVENING AND BEGIN TO DIMINISH SUN MORNING WITH FALLING INVERSION HEIGHTS AND SFC RIDGING SHIFTING WINDS TO THE SW. TEMPS WILL REMAIN COLD THROUGH THE PERIOD WITH HIGHS RAGING 10 TO 15 DEGREES BELOW NORMAL. HAVE OPTED TO UNDERCUT GUIDANCE TEMPS GIVEN ANOMALOUSLY COLD CONDITIONS PRESENT. && .LONG TERM... ...MONDAY THROUGH FRIDAY... COMPLICATED AND LOW CONFIDENCE LONG TERM FORECAST DUE TO HIGHLY ENERGETIC AND COMPLICATED MID AND UPPER LEVEL FLOW OVER PACIFIC AND WESTERN NORTH AMERICA. STILL EXPECT BELOW NORMAL TEMPERATURES FOR A LARGE PART OF THE PERIOD AND POTENTIAL FOR A MODERATE TO HEAVY PRECIPITATION EVENT MID WEEK. WATER VAPOR THIS MORNING SHOWS A VERY ENERGETIC PATTERN...SIMILAR TO LAST YEAR ABOUT THIS TIME. AS DISCUSSED LAST NIGHT...MODELS LIKELY NOT RESOLVING FEATURES OVER THE PACIFIC WELL GIVEN LIMITED SAMPLING MEASURES. FIRST AREA OF CONCERN IS WITH IMPRESSIVE LOOKING SUB-TROPICAL MOISTURE PLUME DEVELOPING NEAR 15N AND 120W. MODELS TRYING TO PICK UP ON THIS BUT CONCERNED THEY ARE NOT NEAR STRONG ENOUGH GIVEN DEPICTION IN WATER VAPOR. THIS AREA EXPECTED TO CONTINUE SPREADING NORTHEAST AND WILL FEED INTO DEVELOPING MID LEVEL LOW OFF OF CA COAST THAT WILL BECOME OUR WEATHER MAKER FOR MID WEEK. SECONDARY AREA OF CONCERN IS WITH STRONG JET CORE NEAR 40N AND 150W. MODELS DO SEEM TO HAVE A HANDLE ON THIS FEATURE...BUT GIVEN ITS STRENGTH THERE IS SOME CONCERN WITH HOW IT WILL EVOLVE OVER WESTERN CONUS. THIS IS A LARGE PART OF THE DIFFERENCES IN MODEL SOLUTIONS FOR MID WEEK. IT WILL BE THE INTERACTION OF THESE TWO PACIFIC FEATURES WITH THE MID LEVEL LOW ACROSS THE SOUTHWEST CONUS THAT DETERMINES ITS EVOLUTION AND IMPACT ON OUR AREA. AS MENTIONED LAST NIGHT...WE FELT MODELS WERE NOT HANDLING THIS ENERGY WELL AND A STRONGER SYSTEM WAS EXPECTED. LATEST MEDIUM RANGE SOLUTIONS ARE INDEED STRONGER...WITH GFS BEING THE STRONGEST. COMPLICATIONS FOR OUR FORECAST AREA WILL BE WITH AMOUNT OF WARM AIR ADVECTION AHEAD OF SYSTEM AND ITS ACTUAL TRACK. ECMWF WHILE WEAKER IS FURTHER NORTH WITH STRONG WAA AND MOISTURE INFLUX INTO THE AREA LATE MONDAY NIGHT AND TUESDAY...INDICATING A POSSIBLE HEAVY RAIN EVENT. GFS IS STRONGER AND FURTHER SOUTH WITH COLDER AIR OVER NORTHERN HALF OF FORECAST AREA...YIELDING A POSSIBLE RAIN EVENT SOUTH AND SNOW NORTH. BOTH SOLUTIONS PLAUSIBLE AND AGAIN WILL LIKELY NOT BE RESOLVED UNTIL SYSTEM GETS WITHIN RADIOSONDE NETWORK. AGREEMENT LIES WITH SOME TYPE OF PRECIPITATION EVENT WITH POTENTIAL FOR HEAVY PCPN SOMEWHERE IN THE WESTERN LAKES OR OHIO VALLEY REGION FROM LATE MONDAY NIGHT INTO EARLY WEDNESDAY. HAVE INCREASED POPS DURING THIS WINDOW WITH LIKELY POPS CENTERED ON TUESDAY. STAYED WITH ALL SNOW MONDAY NIGHT WITH INITIAL COLDER AIR IN PLACE AND LOWER WET BULB TEMPERATURES. ALSO STAYED WITH RAIN OR SNOW MENTION TUESDAY GIVEN UNCERTAINTY IN TRACK AND THERMAL FIELDS. BEYOND WEDNESDAY FEW CHANGES WERE MADE. MODELS CONTINUE TO INDICATE SOME TYPE OF COLDER AIR INTRUSION BUT NOT NEAR AS STRONG AS 48 HOURS AGO. THUS KEPT IDEA OF SLIGHTLY BELOW NORMAL TEMPERATURES. CLIPPER SYSTEM POSSIBLE BY END OF WEEK BUT AGAIN QUITE A BIT OF DISAGREEMENT IN MODELS SO NO CHANGES MADE. SOME SIGNALS TO A PATTERN CHANGE WELL BEYOND DAY 7...TOWARD MID MONTH. ENSEMBLES SHOWING WESTERN CONUS RIDGE BEING REPLACED BY DEEP TROUGH WITH FLOW OVER OUR AREA BECOMING MORE SOUTHWEST AND POSSIBLY ACTIVE. && AVIATION.../06Z TAFS/ CLIPPER SYSTEM WILL MOVE THROUGH THE REGION DURING THE PERIOD...BRINGING DETERIORATING FLIGHT CONDITIONS TO THE REGION. EXPECTING A PERIOD OF MVFR CIGS/VISBY WITH THE SYNOPTIC SYSTEM AT SBN AND FWA. THIS LINES UP WELL WITH MOS AND UPSTREAM OBS. STRONG GUSTY SOUTHERLY WINDS WILL BE EXPECTED GIVEN VERY STRONG FLOW OFF THE SFC AND A TIGHT PRESSURE GRADIENT IN PLACE. COLD FRONT WILL PUSH THROUGH THE REGION LATE MORNING AND EARLY AFTERNOON...ALLOWING WINDS TO VEER WESTERLY. GUSTS OF 25 TO 30 KNOTS WILL SUPPORT AREAS OF BLOWING SNOW...WHICH COULD ALLOW FOR BRIEF VISBY REDUCTIONS ACROSS THE FA. LAKE EFFECT SNOWS WILL DEVELOP AND SHIFT SOUTH INTO THE NORTHWEST FA...WITH IFR/LIFR CONDITIONS LIKELY THERE BY EVENING IN A COMBINATION OF BLOWING SNOW AND HEAVY LAKE SNOWS. HAVE TRENDED SBN IN THIS DIRECTION. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 7 AM EST SUNDAY FOR INZ004-005. MI...WINTER STORM WARNING UNTIL 7 AM EST SUNDAY FOR MIZ077-078. WINTER WEATHER ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ079. OH...NONE. LM...GALE WARNING UNTIL 3 AM EST SUNDAY FOR LMZ043-046. && $$ SHORT TERM...JC LONG TERM...LASHLEY AVIATION...JC in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1233 PM EST SAT DEC 6 2008 .AVIATION... SYNOPTIC SCALE SNOW WITH ACCOMPANYING IFR VSBYS WILL BE MOVG OUT OF NRN INDIANA EARLY THIS AFTN AS CDFNT MOVES THROUGH THE AREA. WINDS WILL SHIFT TO NW BEHIND THE FRONT CAUSING LAKE EFFECT SNOW SHOWERS TO SPREAD INTO NRN INDIANA BY THIS EVE AND CONTINUING THROUGH SUNDAY MORNING. EXPECTING PREDOMINANTLY IFR CONDITIONS AT SBN DURING THE LAKE EFFECT EPISODE AND MVFR AT FWA. && .PREV DISCUSSION... /ISSUED 932 AM EST SAT DEC 6 2008/ UPDATE... AREA OF SNOW MOVG ACROSS CWA ATTM. SNOW FALLING IN WAA REGIME AHEAD OF LOW MOVG SE ACROSS NRN LM. WRN EDGE OF AREA OF PRECIP JUST AHEAD OF THE SYSTEMS COLD FRONT... LOOSES MID LEVEL MOISTURE RESULTING IN SOME FREEZING DRIZZLE...HAVE ADDED MENTION OF PATCHY FREEZING DRIZZLE TO SE 2/3 OF CWA AS FRONT MOVES THROUGH TODAY. UPSTREAM TEMPS AND CONTD WAA AHEAD OF FRONT SUGGEST GOING HIGHS FOR TODAY ARE A BIT ON THE COLD SIDE AND GENERALLY RAISED ABOUT 3F. OTRWS NO SGFNT CHANGES MADE ATTM. && SHORT TERM... .WINTER WEATHER TO IMPACT THE REGION TODAY AND TONIGHT... TODAY THROUGH SUNDAY NIGHT RATHER POTENT SHORTWAVE TROUGH AND ASSOCIATED SFC CYCLONE IS PUSHING INTO THE GREAT LAKES REGION. AN AREA ON LIGHT TO MODERATE SNOW IS ONGOING OVER PORTIONS OF IL/IN/WI IN THE WARM CONVEYOR BELT PORTION OF THE SYSTEM...WHERE A 50 KNOT LL JET IS AIDING IN WEAK MOISTURE ADVECTION AND CROSS ISOBARIC FLOW...LENDING TO UPGLIDE. VERY DRY COLUMN AS INDICATED BY ILX AND DVN SOUNDINGS IS ACTING TO LIMIT SNOWFALL SOMEWHAT...SUPPORTING WIDESPREAD VIRGA UNTIL SATURATION IS REACHED. THIS IS EVIDENT IN THE DONUT HOLE SIGNATURES THAT WERE OBSERVED AT DVN/ILX/AND LOT. REGARDLESS...ONCE SATURATION IS REACHED...EXPECTING A PERIOD OF LIGHT TO MODERATE SNOW TO OVERSPREAD THE REGION...SUPPORTING A QUICK BURST OF 1 TO 2 INCHES OF SNOW...WITH 1 INCH AMOUNTS MORE THE NORM. RATHER ROBUST TROPOPAUSE PRESSURE RISES COUPLED WITH STEEP MID LEVEL LAPSE RATES AND DECENT MOISTURE CONVERGENCE WILL CONTINUE TO SO SUPPORT BROAD LIFT THROUGH MUCH OF THE MORNING AND ACROSS THE FA. HAVE FAVORED THE SREF AND GFS WRT QPF GUIDANCE WITH THE CLIPPER SYSTEM...BUT OPTED FOR THE SUPPORT OF THE NAM12 FOR LAKE EFFECT PROCESSES. ALSO UTILIZED THE RUC13 FOR ADDED GUIDANCE. TODAY...CLIPPER SYSTEM WILL QUICKLY LEAVE GENERALLY 1 INCH OF SNOWFALL ACROSS THE MAJORITY OF THE FA. IN ADDITION STAUNCH FLOW/A RATHER TIGHT PRESSURE GRADIENT/STRONG FLOW ALOFT...45 TO 50 KNOTS OF H95 GEOSTROPHIC FLOW/AND LINKED MOMENTUM UNDER CAA WILL SUPPORT GUSTY WESTERLY WINDS. SUSTAINED WINDS OF 15 TO 25 MPH WITH HIGHER GUSTS ARE EXPECTED THROUGH THE EVENING. THIS WILL ALLOW FOR AREAS OF BLOWING AND DRIFTING SNOW...MAKING TRAVEL DIFFICULT IN SOME AREAS. ROBUST CAA WITH H85 T/S DROPPING 5 TO 6C WILL HELP SUPPORT INCREASED INSTABILITY OVER LK MI THIS AFTERNOON. WESTERLY FLOW AT FIRST WILL LIMIT LK SNOW SHOWERS TO MAINLY MI THIS AFTERNOON. LL FLOW WILL CONTINUE TO VEER BEHIND THE COLD FRONT...INCREASING THE FLOW FETCH OVER LK MI...WITH PRECONDITIONED FLOW FROM LAKE SUPERIOR DEVELOPING. A SECONDARY UPPER IMPULSE WILL ACT TO FURTHER INCREASE INVERSION HEIGHTS ALREADY MODIFIED BY LAKE AGGREGATE EFFECTS FROM LK SUPERIOR. THE NET EFFECT WILL BE LAKE INDUCED CAPES OF 500 TO 700 J/KG WITH MAX UPWARD OMEGA IN THE DGZ. THIS WILL FAVOR THE DEVELOPMENT OF SEVERAL INTENSE BANDS OF LK EFFECT SNOW...CONGEALING INTO ONE DOMINATE BAND AS CONVECTIVE INFLUENCES EVENTUALLY OUTWEIGH WIND SHEAR EFFECTS. NAM12 AND RUC 13 PROGS HAVE CONSISTENTLY BEEN SUPPORTING THE PLACEMENT OF THIS BAND OVER EASTERN BERRIEN AND CASS COUNTIES. HIRES WRF SIMULATIONS FURTHER SUPPORT THIS IDEA. SNOWFALL RATES OF 2 TO 4 INCHES PER HOUR ARE WILL BE POSSIBLE WITH AN INTENSE DOMINATE BAND...ESPECIALLY IF THE LL MASS FIELD READJUSTS TO THE MESOSCALE PROCESS...ENHANCING LL CONVERGENCE. HAVE ISSUED A WINTER STORM WARNING FOR BERRIEN AND CASS COUNTIES...WITH 1 TO 2 INCHES OF SNOWFALL THIS MORNING/PERIODS OF LAKE EFFECT SNOW THIS AFTERNOON WITH AND ADDITIONAL 2 TO 3 INCHES POSSIBLE/BLOWING SNOW THROUGH THE DAY AND NIGHT SIGNIFICANTLY REDUCING VISIBILITIES/AND ADDITIONAL HEAVY LAKE EFFECT SNOW WITH AN ADDITIONAL 4 TO 8 INCHES POSSIBLE. OPTED FOR A WINTER WEATHER ADV FOR ST. JOE IN/MI AND ELKHART FOR COMBINATION OF LAKE EFFECT SNOW AND BLOWING SNOW WITH 3 TO 6 INCHES POSSIBLE BY SUNDAY MORNING. IT IS QUITE POSSIBLE THAT LAGRANGE AND MAYBE NOBLE COUNTIES MAY HAVE TO BE ADDED TO THE ADV AS CURRENT MODEL GUIDANCE CERTAINLY HINTS AT A PERIOD OF INTENSE LL OMEGA CENTERED OVER THESE COUNTIES. HEAVIEST LAKE SNOWS WILL OCCUR SAT EVENING AND BEGIN TO DIMINISH SUN MORNING WITH FALLING INVERSION HEIGHTS AND SFC RIDGING SHIFTING WINDS TO THE SW. TEMPS WILL REMAIN COLD THROUGH THE PERIOD WITH HIGHS RAGING 10 TO 15 DEGREES BELOW NORMAL. HAVE OPTED TO UNDERCUT GUIDANCE TEMPS GIVEN ANOMALOUSLY COLD CONDITIONS PRESENT. LONG TERM... .MONDAY THROUGH FRIDAY... COMPLICATED AND LOW CONFIDENCE LONG TERM FORECAST DUE TO HIGHLY ENERGETIC AND COMPLICATED MID AND UPPER LEVEL FLOW OVER PACIFIC AND WESTERN NORTH AMERICA. STILL EXPECT BELOW NORMAL TEMPERATURES FOR A LARGE PART OF THE PERIOD AND POTENTIAL FOR A MODERATE TO HEAVY PRECIPITATION EVENT MID WEEK. WATER VAPOR THIS MORNING SHOWS A VERY ENERGETIC PATTERN...SIMILAR TO LAST YEAR ABOUT THIS TIME. AS DISCUSSED LAST NIGHT...MODELS LIKELY NOT RESOLVING FEATURES OVER THE PACIFIC WELL GIVEN LIMITED SAMPLING MEASURES. FIRST AREA OF CONCERN IS WITH IMPRESSIVE LOOKING SUB-TROPICAL MOISTURE PLUME DEVELOPING NEAR 15N AND 120W. MODELS TRYING TO PICK UP ON THIS BUT CONCERNED THEY ARE NOT NEAR STRONG ENOUGH GIVEN DEPICTION IN WATER VAPOR. THIS AREA EXPECTED TO CONTINUE SPREADING NORTHEAST AND WILL FEED INTO DEVELOPING MID LEVEL LOW OFF OF CA COAST THAT WILL BECOME OUR WEATHER MAKER FOR MID WEEK. SECONDARY AREA OF CONCERN IS WITH STRONG JET CORE NEAR 40N AND 150W. MODELS DO SEEM TO HAVE A HANDLE ON THIS FEATURE...BUT GIVEN ITS STRENGTH THERE IS SOME CONCERN WITH HOW IT WILL EVOLVE OVER WESTERN CONUS. THIS IS A LARGE PART OF THE DIFFERENCES IN MODEL SOLUTIONS FOR MID WEEK. IT WILL BE THE INTERACTION OF THESE TWO PACIFIC FEATURES WITH THE MID LEVEL LOW ACROSS THE SOUTHWEST CONUS THAT DETERMINES ITS EVOLUTION AND IMPACT ON OUR AREA. AS MENTIONED LAST NIGHT...WE FELT MODELS WERE NOT HANDLING THIS ENERGY WELL AND A STRONGER SYSTEM WAS EXPECTED. LATEST MEDIUM RANGE SOLUTIONS ARE INDEED STRONGER...WITH GFS BEING THE STRONGEST. COMPLICATIONS FOR OUR FORECAST AREA WILL BE WITH AMOUNT OF WARM AIR ADVECTION AHEAD OF SYSTEM AND ITS ACTUAL TRACK. ECMWF WHILE WEAKER IS FURTHER NORTH WITH STRONG WAA AND MOISTURE INFLUX INTO THE AREA LATE MONDAY NIGHT AND TUESDAY...INDICATING A POSSIBLE HEAVY RAIN EVENT. GFS IS STRONGER AND FURTHER SOUTH WITH COLDER AIR OVER NORTHERN HALF OF FORECAST AREA...YIELDING A POSSIBLE RAIN EVENT SOUTH AND SNOW NORTH. BOTH SOLUTIONS PLAUSIBLE AND AGAIN WILL LIKELY NOT BE RESOLVED UNTIL SYSTEM GETS WITHIN RADIOSONDE NETWORK. AGREEMENT LIES WITH SOME TYPE OF PRECIPITATION EVENT WITH POTENTIAL FOR HEAVY PCPN SOMEWHERE IN THE WESTERN LAKES OR OHIO VALLEY REGION FROM LATE MONDAY NIGHT INTO EARLY WEDNESDAY. HAVE INCREASED POPS DURING THIS WINDOW WITH LIKELY POPS CENTERED ON TUESDAY. STAYED WITH ALL SNOW MONDAY NIGHT WITH INITIAL COLDER AIR IN PLACE AND LOWER WET BULB TEMPERATURES. ALSO STAYED WITH RAIN OR SNOW MENTION TUESDAY GIVEN UNCERTAINTY IN TRACK AND THERMAL FIELDS. BEYOND WEDNESDAY FEW CHANGES WERE MADE. MODELS CONTINUE TO INDICATE SOME TYPE OF COLDER AIR INTRUSION BUT NOT NEAR AS STRONG AS 48 HOURS AGO. THUS KEPT IDEA OF SLIGHTLY BELOW NORMAL TEMPERATURES. CLIPPER SYSTEM POSSIBLE BY END OF WEEK BUT AGAIN QUITE A BIT OF DISAGREEMENT IN MODELS SO NO CHANGES MADE. SOME SIGNALS TO A PATTERN CHANGE WELL BEYOND DAY 7...TOWARD MID MONTH. ENSEMBLES SHOWING WESTERN CONUS RIDGE BEING REPLACED BY DEEP TROUGH WITH FLOW OVER OUR AREA BECOMING MORE SOUTHWEST AND POSSIBLY ACTIVE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY UNTIL 5 PM EST /4 PM CST/ THIS AFTERNOON FOR INZ003-006>009-012>018-020-022>027-032>034. WINTER WEATHER ADVISORY UNTIL 7 AM EST SUNDAY FOR INZ004-005. MI...WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ080- 081. WINTER WEATHER ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ079. WINTER STORM WARNING UNTIL 7 AM EST SUNDAY FOR MIZ077-078. OH...WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR OHZ001- 002-004-005-015-016-024-025. LM...GALE WARNING UNTIL 3 AM EST SUNDAY FOR LMZ043-046. && $$ SHORT TERM...JC LONG TERM...LASHLEY AVIATION...TAYLOR UPDATE...TAYLOR in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 442 PM EST SAT DEC 6 2008 .SYNOPSIS... 20Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING OVER THE WESTERN U.S. AND A TROUGH EXTENDING FROM HUDSON BAY SOUTHWARD INTO THE TENNESSEE VALLEY. UPPER MI SITS IN THE MIDDLE OF THE TROUGH AXIS...AND RIGHT UNDERNEATH A SHRTWV AT 500MB. DPVA FORCING WITH THE SHRTWV COMBINED WITH LAKE EFFECT AND A COLD FRONT TO GENERATE A BAND OF HEAVY SNOWFALL THAT MOVED THROUGH UPPER MI EARLY THIS AFTN. THE COLD FRONT IS ASSOCIATED WITH A 1001 MB LOW...LOCATED NOW NEAR DRUMMOND ISLAND. WITH THE SHRTWV OVER UPPER MI...THE CWA IS BEGINNING TO SEE DNVA AND LOWERING INVERSIONS...AS NOTED BY 12Z SOUNDINGS FROM INL AND CWPL. NUMEROUS LAKE EFFECT MULTI-PARALLEL BANDS HAVE DEVELOPED WITH COLD AIR FLOWING IN UNDERNEATH THE INVERSION...MOST INTENSE OVER THE NORTH CENTRAL AND EAST WITH THE LONGER FETCH OF NW WINDS. 850MB TEMPS PER RUC ANALYSIS RANGED FROM -20C WEST TO -15C EAST. DESPITE THE COLD AIRMASS...LAKE EFFECT IS DIMINISHING OVER WESTERN LAKE SUPERIOR THANKS TO DRIER AIR ADVECTING IN OUT OF MN. THIS DRIER AIR IS NOTED BY THE 12Z INL AND CWPL SOUNDINGS HAVING PRECIPITABLE WATER VALUES LESS THAN 0.10 OF AN INCH AND SFC DEWPOINTS BELOW ZERO F. THE DRIER AIR IS ALSO ASSOCIATED WITH A HIGH PRESSURE RIDGE THAT COVERS MANITOBA AND NORTH DAKOTA. FARTHER TO THE WEST...MID AND HIGH CLOUDS ARE MOVING ACROSS THE WESTERN DAKOTAS AND EASTERN MONTANA...ASSOCIATED WITH WARM ADVECTION AHEAD OF A SHRTWV MOVING THROUGH CENTRAL BRITISH COLUMBIA AND ALBERTA. FOR LATEST SNOWFALL REPORTS AND BLOWING SNOW IMPACTS...SEE ARBLSRMQT. && .SHORT TERM (TONIGHT AND SUN)... UPPER LEVEL HEIGHTS ARE PROGGED TO RISE DURING THE NEXT 24 HOURS AS THE TROUGH AXIS PUSHES OFF TO THE EAST. THEREFORE...INVERSIONS WILL CONTINUE TO LOWER ACROSS THE CWA WHILE DRIER AIR ADVECTS IN FROM THE WEST. THE COMBINATION OF BOTH FACTORS SHOULD ALLOW SNOW SHOWERS TO BECOME SCATTERED OVER WESTERN UPPER MI TONIGHT WITH MUCH LESS ACCUMULATION. GOING END TIMES FOR THE WARNINGS FOR WESTERN UPPER MICHIGAN AT 7 PM EST THIS EVENING LOOK GOOD. FOR NORTH CENTRAL AND EASTERN UPPER MICHIGAN...THE LONGER FETCH OF NW WINDS COMBINED WITH LAND BREEZES COMING OUT OF WESTERN UPPER MI SHOULD KEEP THE LAKE EFFECT GOING LONGER. IN ADDITION...UPSTREAM MOISTENING OFF LAKE NIPIGON IS EXPECTED...AS IS OCCURRING ATTM. IN FACT...LAST FEW RUC RUNS AND OUR LOCAL WRF-ARW RUNS SUGGEST A SINGLE BAND FROM LAKE NIPIGON...OFF THE TIP OF THE KEWEENAW AND INTO THE ALGER/DELTA/MARQUETTE COUNTY LINES. THIS SEEMS REASONABLE AS THE LAND BREEZE DEVELOPS AND CONVERGES ON THE GENERAL NNW TO NW FLOW BEHIND THE DEPARTING SFC LOW. SHOULD THE BAND STAY IN PLACE... SOUNDINGS AND MODEL DERIVED QPF AMOUNTS SUGGEST THAT 1 INCH PER HOUR RATES ARE REASONABLE. THEREFORE...WILL CONTINUE WARNINGS FOR ALGER...DELTA AND MARQUETTE COUNTIES. SCHOOLCRAFT AND LUCE COUNTIES ARE A LITTLE MORE TROUBLESOME...AND WAS TEMPTED TO DROP THE WARNINGS AS ONLY THE MULTI-PARALLEL BANDS ARE EXPECTED THERE. HOWEVER...WITH THE WIND BLOWING THE SNOW THIS EVENING AND THE WARNING ONLY BEING UP FOR ABOUT 3 TO 4 HOURS SO FAR...HAVE DECIDED TO LEAVE IT UP FOR NOW. LAKE EFFECT OVER THE NORTH CENTRAL AND EAST SHOULD GRADUALLY DIMINISH ON SUNDAY AS THE DRIER AIR OVER WESTERN UPPER MI BUILDS IN THERE. STILL MAINTAINED LIKELY POPS SUNDAY AFTN FOR NORTHERN SCHOOLCRAFT/LUCE AS IT LOOKS LIKE THE LAKE NIPIGON ENHANCED BAND WILL SHIFT IN THERE. BESIDES THE LAKE EFFECT...ANOTHER POSSIBLE PCPN IMPACT IS SOME WARM ADVECTION -SN MOVING IN SUNDAY AFTN. THIS WARM ADVECTION PCPN IS ASSOCIATED WITH THE MID/HIGH CLOUD IN THE WESTERN DAKOTAS AND EASTERN MONTANA. THE CANADIAN MODEL WAS VERY AGGRESSIVE BRINGING THIS PCPN INTO UPPER MI...MAKING ITS WAY INTO THE CENTRAL U.P.. HOWEVER...IT IS AN OUTLIER AND PROBABLY TOO FAST GIVEN THAT SOUNDINGS SHOW PLENTY OF DRY AIR. INSTEAD...FOLLOWED THE GFS/LOCAL WRF-ARW RUNS WHICH ONLY BRING A HUNDREDTH OF QPF INTO FAR WESTERN UPPER MI. ANOTHER ISSUE FOR THE FORECAST IS TEMPS TONIGHT. IT APPEARS SOME OF THE WI BORDER AREAS COULD CLEAR OUT. GIVEN FRESH SNOW AND THE DRY AIRMASS MOVING IN...TEMPS WOULD PLUMMET ASSUMING WINDS BECOME CALM. LOWERED MINS ALONG THE WI BORDER OF GOGEBIC AND IRON COUNTIES TO 0 TO 5 BELOW ZERO...BUT MAY NOT BE LOW ENOUGH IF CLOUDS CLEAR SOONER. FOR SUNDAY...WITH THE HIGH CLOUDS MOVING IN DURING THE AFTERNOON AND A COLD AIRMASS IN PLACE (850MB TEMPS ONLY REACHING -16C AT 18Z)...FOLLOWED SIMILARLY TO THE MIDNIGHT SHIFT OF STAYING WITH THE COLDER MAV GUIDANCE READINGS FOR HIGHS. .LONG TERM (SUN NIGHT THROUGH NEXT SATURDAY)... UPPER FLOW CONTINUES TO BE FROM THE NW THROUGH THE PERIOD WITH TROUGHING IN THE AREA WITH MORE TROUGHING DIGGING TOWARDS THE AREA FOR TUE. NAM SHOWING 850-500 MB Q-VECTOR CONVERGENCE AND MOISTURE MOVING THROUGH THE AREA SUN NIGHT INTO MON MORNING BEFORE BOTH MOVE OUT BY MON AFTERNOON. NAM SHOWING ISENTROPIC LIFT ON I280K-I295K SURFACES WITH SOME MOISTURE MOVING ACROSS THE CWA SUN NIGHT WITH THE MOISTURE MOVING OUT MON MORNING EXCEPT IN THE LOWEST LEVELS ON I280K SURFACE WHICH LINGERS. GFS SHOWS SOME ISENTROPIC LIFT ON I280K SURFACE WITH MOISTURE AS WELL SUN NIGHT AND THE MOISTURE MOVES OUT ON MON. BASICALLY...LOOKS LIKE RIGHT NOW...THIS SYSTEM FOR SUN NIGHT GOES MOSTLY TO THE SOUTH OF CWA AND DOES NOT LOOK LIKE HEADLINES WILL BE NEEDED. ONLY EXCEPTION AND WILL NEED TO BE WATCHED IS LUCE AND SCHOOLCRAFT COUNTIES WHERE THERE COULD BE A LAKE MICHIGAN BAND THAT FORMS FROM THE SOUTH WINDS THAT OCCUR AND THIS COULD POSSIBLY BE ACROSS THE EASTERN PORTIONS OF THOSE TWO COUNTIES. IT IS COLD ENOUGH FOR LAKE EFFECT TO FORM AND WITH WINDS CONVERGING ACROSS EASTERN LAKE MICHIGAN...A LONG FETCH WOULD FORM. ONLY THING IS THERE COULD BE ENOUGH OF A LAND BREEZE TO PUSH THIS BAND A BIT FURTHER EAST AND KEEP OUT OF THOSE TWO COUNTIES AS WELL. THE LAND BREEZE COULD ALSO DISRUPT THE BAND AS WELL. WILL MENTION THIS IN THE HWO PRODUCT FOR NOW AND NOT HIGHLIGHT...BUT THIS POSSIBILITY OF A HEAVY LAKE EFFECT BAND WILL HAVE TO BE WATCHED. CHANGE FOR THIS FORECAST WAS ALSO TO GO LIKELY POPS LATE SUNDAY NIGHT FOR ALL OF CWA WITH DEEP MOISTURE. FOR TUESDAY...SIGNIFICANT TROUGH DIGGING CAUSES A SYSTEM TO COME UP FROM THE SW. SOUTHERN CWA IS ON THE NORTHERN END OF THIS SYSTEM WITH LAKE EFFECT ACROSS THE REST OF THE CWA. SIGNIFICANT SYSTEM SNOW WOULD BE ACROSS THE SOUTHERN CWA AND BUMPED POPS UP TO LIKELY FOR THIS AREA. IF THIS SYSTEM COMES A BIT FURTHER NORTH...THEN WILL HAVE TO BE WATCHED AS WELL. SUBSEQUENT MODEL RUNS WILL HELP TO DETERMINE IF THIS SYSTEM WILL AFFECT US MORE WITH HEAVIER SNOW OR NOT. IN THE EXTENDED...GFS...ECMWF AND CANADIAN ALL SHOW A 500 MB TROUGH ACROSS THE CENTRAL U.S. WITH RIDGING IN THE WESTERN U.S. 00Z WED. MORE TROUGHING COMES IN FOR 00Z THU AND REMAINS THROUGH 00Z SUN. LOOKS PRETTY ACTIVE IN THE EXTENDED AND LOOKS LIKE REPEAT LAKE EFFECT EVENT EPISODES WITH ALBERTA CLIPPER TYPE SYSTEMS MOVING THROUGH EVERY SO OFTEN. BROADBRUSHED THE EXTENDED AND KEPT SOME POPS IN NEAR LAKE SUPERIOR EVERY DAY WITH COLD ENOUGH AIR AROUND AND SOME SHORTWAVES NEAR THE AREA AS WELL. TEMPERATURES LOOK TO STAY BELOW NORMAL.USED THE ECMWF AS GUIDANCE FOR THIS EXTENDED FORECAST AND DID NOT STRAY TOO MUCH FROM IT. CLIPPER SYSTEM MOVES THROUGH WED NIGHT AND THIS LOOKS TO BE THE BEST CHANCE FOR WIDEPSREAD SNOW THEN. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... ARCTIC FRONT HAS PUSHED THROUGH BOTH TAF SITES...WITH BLUSTERY MULTI-PARALLEL BAND LAKE EFFECT SNOW SET UP IN ITS WAKE. WOULD EXPECT CONDITIONS TO BOUNCE BACK AND FORTH BTWN IFR AND LIFR AND BOTH TAF SITES THROUGH THE REST OF THE AFTN AS BANDS MOVE THROUGH. THERE IS A CHANCE VSBYS COULD DROP TO VLIFR BUT NOT HIGH ENOUGH TO INCLUDE EVEN IN A TEMPO GROUP ATTM. TONIGHT...A SINGLE BAND OF SNOW FROM LAKE NIPIGON ACROSS CENTRAL LAKE SUPERIOR MAY BECOME STATIONARY FOR A FEW HOURS AT SAW...WITH ENOUGH CONFIDENCE TO AT LEAST INCLUDE LIFR CONDITIONS. OTHERWISE...IMPROVEMENT IS EXPECTED THROUGH THE NIGHT AS WINDS DIMINISH AND DRIER AIR WORKS IN FROM MN...WITH VSBYS REACHING VFR BY SUNRISE. CIGS WILL REACH VFR LATE SUNDAY MORNING AS THE DRIER AIR AND WINDS BACKING TOWARDS THE WEST AND EVENTUALLY SW HELP TO BREAK UP THE CLOUDS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... NORTH GALES OF UP TO 45 KNOTS...STRONGEST ON EASTERN SUPERIOR...WILL DIMINISH BELOW 30 KT AFTER MIDNIGHT AS A RIDGE OF HIGH PRESSURE BUILDS IN FROM THE DAKOTAS. EXPECT WINDS TO GENERALLY REMAIN AT OR BELOW 30 KNOTS THEN THROUGH MONDAY NIGHT. ON TUESDAY...AN AREA OF LOW PRESSURE DEVELOPING OVER THE SOUTHERN PLAINS IS EXPECTED TO MOVE NORTHEAST...REACHING THE EASTERN GREAT LAKES ON WEDNESDAY. A PERIOD OF NORTH GALES TO 35 KNOTS ARE POSSIBLE BEHIND THE LOW OVER EASTERN LAKE SUPERIOR TUESDAY NIGHT...THEN WINDS WILL DROP BACK DOWN BELOW 30 KNOTS FOR WEDNESDAY AND THURSDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... BLIZZARD WARNING UNTIL 10 AM EST SUNDAY FOR MIZ006-085. BLIZZARD WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ001-003. WINTER STORM WARNING UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR MIZ002-009. WINTER STORM WARNING UNTIL 10 AM EST SUNDAY FOR MIZ007. WINTER STORM WARNING UNTIL 7 AM EST SUNDAY FOR MIZ005-013-014. LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ084. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ004. LAKE SUPERIOR... GALE WARNING UNTIL 3 AM EST SUNDAY FOR LSZ248>251-265>267. GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LSZ263-264. GALE WARNING UNTIL MIDNIGHT EST TONIGHT FOR LSZ242>245. LAKE MICHIGAN... GALE WARNING UNTIL 3 AM EST SUNDAY FOR LMZ221-250. && $$ SYNOPSIS/SHORT TERM...AJ LONG TERM...GJM AVIATION...AJ MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1242 PM EST SAT DEC 6 2008 UPDATED AVIATION DISCUSSION FOR 18Z TAF ISSUANCE .UPDATE... GOING FORECAST LOOKS IN PRETTY GOOD SHAPE BASED ON THE LAST FEW HOURS OF RADAR IMAGERY. ARCTIC/POLAR FRONT MOVING SE THROUGH UPPER MI ABOUT AN HOUR TO TWO FASTER COMPARED TO PREVIOUS RUNS...BUT IT WORKS OUT ALRIGHT AS THE STRONGER WINDS SEEM TO BE LAGGING THE ARCTIC FRONT BY AN HOUR. WHITEOUT CONDITIONS HAVE BEEN OBSERVED HERE AT OUR OFFICE...IN THE CITY OF MARQUETTE AND ELSEWHERE THAT HAVE BEEN IMPACTED BY THE CONVERGENT BAND OF LAKE EFFECT SNOW ALONG THE FRONT. A FEW VEHICLE ACCIDENTS HAVE ALSO OCCURRED DUE TO THE WHITEOUT CONDITIONS. HAVE BEEN ISSUING SPECIAL WEATHER STATEMENTS TO EMPHASIZE THE HEAVY SNOW BURST ACCOMPANYING THE FRONT. IN THE WAKE OF THE FRONT...LAKE EFFECT BANDS ARE SETTING UP...BUT ARE NOT ALL THAT IMPRESSIVE. HOWEVER...STRONG NORTHERLY FLOW IS HELPING TO INCREASE UPSLOPE...AND THEREFORE A LOT OF THE HEAVIER SNOW SHOWERS ARE BEING OBSERVED OVER THE HIGHER TERRAIN. RECENTLY RECEIVED A REPORT OF 8 INCHES SO FAR IN IRONWOOD AND STILL SNOWING HEAVILY. WINDS SHOULD REMAIN CONVERGENT IN THE IRONWOOD AREA THROUGH THE AFTERNOON...SO THE WARNING FOR THE FAR WEST LOOKS GOOD. ONLY AREA OF CONCERN THAT IS NOT PANNING OUT TOO WELL IS THE BLIZZARD WARNING OF THE KEWEENAW PENINSULA. WINDS HAVE BEEN GUSTING TO BLIZZARD CRITERIA...ESPECIALLY AT P59...BUT THE SNOWFALL HAS BEEN FAIRLY BENIGN OUTSIDE OF THE INITIAL CONVERGENT BAND THAT MOVED THROUGH EARLY THIS MORNING. THIS IS PROBABLY DUE TO THE FACT THAT WINDS ARE NOT CONVERGENT AT ALL...AND LIKELY THE ONLY AREA SEEING HEAVIER SNOW IS THE HIGHEST TERRAIN OF KEWEENAW COUNTY (I.E. DELAWARE AND PHOENIX). WEBCAMS SEEM TO CONFIRM THIS AS WELL. WILL KEEP THE BLIZZARD WARNING GOING...IN CASE SNOW TRIES TO PICK UP A BIT THIS AFTERNOON AS COLDER AIR FILTERS IN. HOWEVER...THIS COLDER AIR WILL ALSO BE DRIER...AS EVIDENCED BY PRECIPITABLE WATER VALUES OF LESS THAN 0.10 OF AN INCH ON THE 12Z SOUNDINGS FROM CWPL AND KINL. UPDATED GRID FORECAST AND WINTER STORM STATEMENT HAVE BEEN ISSUED. NO CHANGES NEEDED TO THE ZFP. && .DISCUSSION... (ISSUED AT 355 AM EST) 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW ERN TROF/WRN RDG CONFIGURATION OVER NAMERICA. A PAIR OF STRONG SHRTWVS NOTED DIGGING SEWD INTO THE TROF IN THE NW FLOW ALF BTWN THESE TWO LARGER SCALE FEATURES. THE FIRST SHRTWV IS SLIDING INTO IA...AND THE SECOND IS MOVING THRU NW ONTARIO. STRONG NW WINDS ALF WITH 00Z H3/H5/H7 WINDS AS HI AS 150KT/90KT/60KT NOTED ON ACYC SIDE OF FIRST SHRTWV. GENERAL LLVL SW FLOW AHEAD OF ACCOMPANYING SFC-H85 TROF IN MN AND ARCTIC COLD FNT MOVING THRU NW MN/ADJOINING ONTARIO HAS CAUSED AREAS OF -SN ACRS NE MN/UPR MI AS ISENTROPIC LIFT/DPVA/H85-5 QVECTOR CNVGC HAS GRDLY SATURATED INITIALLY DRY AIRMASS OVER THE UPR GRT LK AS SHOWN ON THE 00Z GRB RAOB. 00Z INL SDNG SHOWS DEEP SATURATION THRU H3. THE HEAVIEST SN APPEARS TO BE JUST S OF UPR MI IN WI...WHERE DPVA/UPR DVGC AHEAD OF SRN SHRTWV/IN LEFT EXIT OF SUPPORTING JET MAX APPEAR TO BE SHARPEST. THERE IS EVIDENCE AN LES BAND IS FORMING OVER LK MI IN THE SW FLOW AHEAD OF THE SHRTWV COMPLEX. WINDS APPEAR TO HAVE ENUF OF A WLY COMPONENT TO FORCE THIS SN BAND INTO CHIP/MACK COUNTIES OF FAR ERN UPR MI...BUT WL HAVE TO MONITOR IN CASE THE BAND DRIFTS MORE TO THE W. FARTHER UPSTREAM...00Z H85 TEMPS AS LO AS -21C AT YQD BEHIND ARCTIC COLD FNT. THE AIRMASS ALSO DRIEST OUT QUITE A BIT AS WELL WITH SFC DWPTS NEAR -10F/CLRG OF LINGERING LO CLD BEHIND FNT PUSHING SWD NEAR LK WINNIPEG IN NLY FLOW AHEAD OF ARCTIC HI PRES BLDG INTO SASKATCHEWAN. 00Z PWAT WAS 0.07 INCH AT YQD. MAIN FCST CONCERNS THIS PACKAGE ARE GOING HEADLINES/EXPECTED LES AND BLSN INTO SUN. FOR TDAY...THE SECOND SHRTWV IN ONTARIO/ACCOMPANYING ARCTIC COLD FNT WL BE THE MAIN INFLUENCE ON WX ACRS CWA AS FIRST SHRTWV/ACCOMPANYING DYNAMICS WL BE PASSING TO THE S INTO THE LOWER LKS BY 12Z. IN ITS WAKE...THE ONTARIO SHRTWV WL DIG ACRS THE FA WITH ARCTIC COLD FROPA SOON AFT 12Z OVER THE NW AND ARND 18Z OVER THE SE. STILL EXPECTING A PD OF LK ENHANCED HEAVIER SHSN TO ACCOMPANY THE ARRIVAL OF THIS FEATURE OVER AT LEAST THE ZNS NEAR LK SUP AS GUIDANCE SHOWS DPVA/ H85-5 QVECTOR CNVGC/UPR DVGC/DEEP MSTR LINGERING UNTIL DYNAMICS/DEEP MSTR PASS TO THE E AFT 18Z. THE PRESENCE OF SHARP UVV WITHIN THE PRIME SN GROWTH LYR ALSO SUGS A PD OF HEAVY SN. CYC NLY FLOW PROGGED TO INCREASE IN THE WAKE OF THE FNT...WITH H925 WINDS RISING TO 35-40KT PRODUCING STRONG CAD/LLVL DESTABILIZATION. THESE STRONG WINDS WILL FRAGMENT THE SNOW FLAKES INTO A MORE POWDERY SN WITH ARRIVAL OF COLDER/DRIER AIR IN THE AFTN. THE RESULT WILL BE A MORE EFFICIENT REDUCTION IN VSBY...WITH WDSPRD BLSN EVEN AFT THE SN INTENSITY BEGINS TO DIMINISH. LK ENHANCED SN WL EVOLVE TO PURE LES BY LATER IN THE DAY AS H85 TEMPS BOTTOM OUT ARND -18C OVER LK SUP BY 00Z SUN. THE STRONG NNW WINDS...STRONGEST OVER THE CNTRL ZNS...WL PUSH THE SHSN FARTHER INLAND INTO DELTA/SRN SCHOOLCRAFT COUNTIES. OTRW...EXPECT HI TEMPS IN THE MRNG OVER THE W HALF...WITH THE MERCURY FALLING OFF IN THE AFTN WITH ARRIVAL OF COLDER AIR. LOOK FOR PURE LES TNGT WITH RISING HGTS/DNVA/H85-5 QVECTOR DVGC IN WAKE OF DEPARTING SHRTWV/SFC LO. THE INTENSITY OF THE LES/BLSN OVER THE W SHOULD DIMINISH THRU THE NGT WITH THE ARRIVAL OF MUCH DRIER AIR FM THE NW AND APPROACH OF HI PRES RDG AS INVERSION HGTS FCST TO LOWER TO 3K FT DURING THE NGT FM IWD-CMX. BUT STILL EXPECT HI SN/WATER RATIOS THROUGH THE END OF THE EVENT OVER THE W WITH TEMPS WITHIN THE INCRSGLY SHALLOW MOIST LYR ARND A FAVORABLE TEMP OF -15C...ESPECIALLY WITH DIMINISHING WINDS/SN FLAKE FRAGMENTATION. BLIZZARD CONDITIONS OVER ALGER/NRN SCHOOLRAFT COUNTY SHOULD EASE AFT THE EVNG WITH H925 WINDS FCST TO DIMINISH TO ARND 25 KT BY 12Z SUN. LES BANDS SHOULD CONTINUE TO DRIFT FAR INTO DELTA/SRN SCHOOLCRAFT ZNS. OTRW...LONGER FETCH LENGTH ACRS ERN LK SUP WL MITIGATE IMPACT OF DRYING SOMEWHAT. LES CHART WOULD SUG 3-6 INCHES OF SN THRU THE NGT OVER THE E...WITH THE HEAVIER AMTS MOST LIKELY OVER ALGER/NRN SCHOOLCRAFT IN MOST PERSISTENT...FOCUSED LLVL CNVGC SHOWN BY NAM12/LOCAL HI RES WRF-ARW ON E EDGE OF LAND BREEZE OFF THE INTERIOR W HALF. WL TEND TOWARD THE LO END OF MOS GUIDANCE FOR MIN TEMPS FCST CONSIDERING INTENSITY OF THIS SHRTWV/DRYNESS OF AIR UPSTREAM. GOING HEADLINES SEEM TO HAVE THE SITUATION IN HAND FOR TDAY...BUT OPTED TO END THE WRNGS BY 00Z SUN OVER THE W ONCE STRONGEST WINDS (H925 WINDS ABV 25 KTS) ARE FCST TO DIMINISH FOLLOWING PASSAGE OF PRES RISE MAX TO THE SE. WL MAINTAIN GOING HEADLINES AS IS FOR THE E HALF. LES WL DIMINISH W-E ON SUN WITH ARRIVAL OF HI PRES RDG UNDER CONTINUED RISING HGTS. AS LLVL FLOW BACKS AHEAD OF THIS FEATURE... THE LES OVER THE E WL TEND TO SHIFT TO THE E BUT END COMPLETELY FM MQT AND W. HOWEVER...LARGER SCALE NAM/GFS MIGHT BE TOO AGGRESSIVE WITH THIS SHIFT OVER THE E CONSIDERING STRONGER LLVL CNVGC SHOWN BY HIER RES CNDN/WRF-ARW RUNS TO BE MORE PERSISTENT OVER ALGER/NRN SCHOOLCRAFT WITH LAND BREEZE OFF ONTARIO HOLDING UP THE PROGRESS. BUT SINCE WINDS/BLSN WL NO LONGER BE AN ISSUE...WL NOT EXTEND GOING HEADLINE EXPIRATION OF 15Z FOR THESE ZNS. OTRW...SUN WL BE ANOTHER VERY COLD DAY UNDER ARRIVING RDG AXIS AND 850 MB THERMAL TROF WITH H85 TEMPS RANGING FM ABOUT -15C OVER THE W TO -18C OVER THE E BY 00Z MON. MAX TEMPS SHOULD REMAIN IN THE TEENS AT MOST SPOTS EVEN THOUGH THERE WL BE SOME SUNSHINE OVER THE W AND CNTRL BEFORE MORE HI CLDS AHEAD OF NEXT SHRTWV APRCHG FM THE W INVADE LATER IN THE DAY. AS FLOW BACKS TO MORE SSW ON SUN NGT AHEAD OF INCOMING SHRTWV FM THE PLAINS...LINGERING LES OFF LK SUP WL DIMINISH AND END OVER THE E WHILE MID CLD THICKENS WITH DVLPG ISENTROPIC LIFT SHOWN ON THE 275K-285K SFCS (H8 THRU H7). GFS AND ESPECIALLY THE NAM SHOW SHARPER ISENTROPIC LIFT/H85-5 QVECTOR CNVGC PASSING TO THE S OF THE FA. WITH SUPPORT FM THE CNDN MODEL AND NCEP PREFERENCE...WL FOLLOW THE GFS/CNDN SOLN MOST CLOSELY. THESE MODELS SUG A SOMEWHAT HIER POP OVER THE SRN TIER...WITH BOTH ACTUALLY SHOWING SOME UPR DVGC IN LEFT EXIT OF SUPPORTING UPR JET STREAK. LOOKS LIKE MUCH OF THESE DYNAMICS WL BE NECESSARY TO SATURATE INITIALLY DRY AIRMASS...SO WL KEEP POPS IN THE CHC RANGE (20 OVER THE N TO 50 ACRS THE S) EXCEPT OVER SRN MNM COUNTY (60 THERE). ONE OTHER INTERESTING ASPECT OF THE FCST IS THE POTENTIAL FOR AN LES BAND TO DVLP OVER LK MI AND PUSH INTO THE ERN ZNS ON THE HEELS OF A SSW WIND AND H85 TEMPS ARND -13C OVER NRN LK MI AT 12Z MON. WL MAINTAIN GOING HIER POPS TO REFLECT THIS POTENTIAL DOWNWIND OF LK MI. DIMINISHED POPS A BIT ON MON AFTN AS GFS/CNDN SHOW BETTER DYNAMICS SHIFTING TO THE E AND SOME DRYING ALF. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... ARCTIC FRONT HAS PUSHED THROUGH BOTH TAF SITES...WITH BLUSTERY MULTI-PARALLEL BAND LAKE EFFECT SNOW SET UP IN ITS WAKE. WOULD EXPECT CONDITIONS TO BOUNCE BACK AND FORTH BTWN IFR AND LIFR AND BOTH TAF SITES THROUGH THE REST OF THE AFTN AS BANDS MOVE THROUGH. THERE IS A CHANCE VSBYS COULD DROP TO VLIFR BUT NOT HIGH ENOUGH TO INCLUDE EVEN IN A TEMPO GROUP ATTM. TONIGHT...A SINGLE BAND OF SNOW FROM LAKE NIPIGON ACROSS CENTRAL LAKE SUPERIOR MAY BECOME STATIONARY FOR A FEW HOURS AT SAW...WITH ENOUGH CONFIDENCE TO AT LEAST INCLUDE LIFR CONDITIONS. OTHERWISE...IMPROVEMENT IS EXPECTED THROUGH THE NIGHT AS WINDS DIMINISH AND DRIER AIR WORKS IN FROM MN...WITH VSBYS REACHING VFR BY SUNRISE. CIGS WILL REACH VFR LATE SUNDAY MORNING AS THE DRIER AIR AND WINDS BACKING TOWARDS THE WEST AND EVENTUALLY SW HELP TO BREAK UP THE CLOUDS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... STRONG COLD FRONT PLOWING THROUGH ALONG WITH SFC LOW DEEPENING JUST EAST OF LK SUPERIOR RESULTS IN GALES 40-45 KNOTS FOR THE E 2/3 OF LAKE SUPERIOR THROUGH TONIGHT. WINDS DIMINISH BY SUNDAY AS HIGH PRESSURE MOVES ACROSS THE GREAT LAKES. SRLY WINDS ON MONDAY AHEAD OF LOW PRESSURE TROUGH SHOULD REACH 30 KNOTS...MAINLY OVER E 1/2 OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ084. BLIZZARD WARNING FROM 1 PM THIS AFTERNOON TO 10 AM EST SUNDAY FOR MIZ006-085. BLIZZARD WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ001-003. WINTER STORM WARNING UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR MIZ002-009. WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 10 AM EST SUNDAY FOR MIZ007. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ004. WINTER STORM WARNING UNTIL 7 AM EST SUNDAY FOR MIZ005. WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST SUNDAY FOR MIZ013-014. LAKE SUPERIOR... GALE WARNING UNTIL 7 AM EST SUNDAY FOR LSZ248>251-265>267. GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LSZ263-264. GALE WARNING UNTIL 1 AM EST SUNDAY FOR LSZ242>245. GALE WARNING UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR LSZ241. LAKE MICHIGAN... GALE WARNING FROM 4 PM THIS AFTERNOON TO 1 AM EST SUNDAY FOR LMZ221-250. && $$ UPDATE...AJ DISCUSSION...KC AVIATION...AJ MARINE...JLA mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1133 AM EST SAT DEC 6 2008 .UPDATE... GOING FORECAST LOOKS IN PRETTY GOOD SHAPE BASED ON THE LAST FEW HOURS OF RADAR IMAGERY. ARCTIC/POLAR FRONT MOVING SE THROUGH UPPER MI ABOUT AN HOUR TO TWO FASTER COMPARED TO PREVIOUS RUNS...BUT IT WORKS OUT ALRIGHT AS THE STRONGER WINDS SEEM TO BE LAGGING THE ARCTIC FRONT BY AN HOUR. WHITEOUT CONDITIONS HAVE BEEN OBSERVED HERE AT OUR OFFICE...IN THE CITY OF MARQUETTE AND ELSEWHERE THAT HAVE BEEN IMPACTED BY THE CONVERGENT BAND OF LAKE EFFECT SNOW ALONG THE FRONT. A FEW VEHICLE ACCIDENTS HAVE ALSO OCCURRED DUE TO THE WHITEOUT CONDITIONS. HAVE BEEN ISSUING SPECIAL WEATHER STATEMENTS TO EMPHASIZE THE HEAVY SNOW BURST ACCOMPANYING THE FRONT. IN THE WAKE OF THE FRONT...LAKE EFFECT BANDS ARE SETTING UP...BUT ARE NOT ALL THAT IMPRESSIVE. HOWEVER...STRONG NORTHERLY FLOW IS HELPING TO INCREASE UPSLOPE...AND THEREFORE A LOT OF THE HEAVIER SNOW SHOWERS ARE BEING OBSERVED OVER THE HIGHER TERRAIN. RECENTLY RECEIVED A REPORT OF 8 INCHES SO FAR IN IRONWOOD AND STILL SNOWING HEAVILY. WINDS SHOULD REMAIN CONVERGENT IN THE IRONWOOD AREA THROUGH THE AFTERNOON...SO THE WARNING FOR THE FAR WEST LOOKS GOOD. ONLY AREA OF CONCERN THAT IS NOT PANNING OUT TOO WELL IS THE BLIZZARD WARNING OF THE KEWEENAW PENINSULA. WINDS HAVE BEEN GUSTING TO BLIZZARD CRITERIA...ESPECIALLY AT P59...BUT THE SNOWFALL HAS BEEN FAIRLY BENIGN OUTSIDE OF THE INITIAL CONVERGENT BAND THAT MOVED THROUGH EARLY THIS MORNING. THIS IS PROBABLY DUE TO THE FACT THAT WINDS ARE NOT CONVERGENT AT ALL...AND LIKELY THE ONLY AREA SEEING HEAVIER SNOW IS THE HIGHEST TERRAIN OF KEWEENAW COUNTY (I.E. DELAWARE AND PHOENIX). WEBCAMS SEEM TO CONFIRM THIS AS WELL. WILL KEEP THE BLIZZARD WARNING GOING...IN CASE SNOW TRIES TO PICK UP A BIT THIS AFTERNOON AS COLDER AIR FILTERS IN. HOWEVER...THIS COLDER AIR WILL ALSO BE DRIER...AS EVIDENCED BY PRECIPITABLE WATER VALUES OF LESS THAN 0.10 OF AN INCH ON THE 12Z SOUNDINGS FROM CWPL AND KINL. UPDATED GRID FORECAST AND WINTER STORM STATEMENT HAVE BEEN ISSUED. NO CHANGES NEEDED TO THE ZFP. && .DISCUSSION... (ISSUED AT 355 AM EST) 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW ERN TROF/WRN RDG CONFIGURATION OVER NAMERICA. A PAIR OF STRONG SHRTWVS NOTED DIGGING SEWD INTO THE TROF IN THE NW FLOW ALF BTWN THESE TWO LARGER SCALE FEATURES. THE FIRST SHRTWV IS SLIDING INTO IA...AND THE SECOND IS MOVING THRU NW ONTARIO. STRONG NW WINDS ALF WITH 00Z H3/H5/H7 WINDS AS HI AS 150KT/90KT/60KT NOTED ON ACYC SIDE OF FIRST SHRTWV. GENERAL LLVL SW FLOW AHEAD OF ACCOMPANYING SFC-H85 TROF IN MN AND ARCTIC COLD FNT MOVING THRU NW MN/ADJOINING ONTARIO HAS CAUSED AREAS OF -SN ACRS NE MN/UPR MI AS ISENTROPIC LIFT/DPVA/H85-5 QVECTOR CNVGC HAS GRDLY SATURATED INITIALLY DRY AIRMASS OVER THE UPR GRT LK AS SHOWN ON THE 00Z GRB RAOB. 00Z INL SDNG SHOWS DEEP SATURATION THRU H3. THE HEAVIEST SN APPEARS TO BE JUST S OF UPR MI IN WI...WHERE DPVA/UPR DVGC AHEAD OF SRN SHRTWV/IN LEFT EXIT OF SUPPORTING JET MAX APPEAR TO BE SHARPEST. THERE IS EVIDENCE AN LES BAND IS FORMING OVER LK MI IN THE SW FLOW AHEAD OF THE SHRTWV COMPLEX. WINDS APPEAR TO HAVE ENUF OF A WLY COMPONENT TO FORCE THIS SN BAND INTO CHIP/MACK COUNTIES OF FAR ERN UPR MI...BUT WL HAVE TO MONITOR IN CASE THE BAND DRIFTS MORE TO THE W. FARTHER UPSTREAM...00Z H85 TEMPS AS LO AS -21C AT YQD BEHIND ARCTIC COLD FNT. THE AIRMASS ALSO DRIEST OUT QUITE A BIT AS WELL WITH SFC DWPTS NEAR -10F/CLRG OF LINGERING LO CLD BEHIND FNT PUSHING SWD NEAR LK WINNIPEG IN NLY FLOW AHEAD OF ARCTIC HI PRES BLDG INTO SASKATCHEWAN. 00Z PWAT WAS 0.07 INCH AT YQD. MAIN FCST CONCERNS THIS PACKAGE ARE GOING HEADLINES/EXPECTED LES AND BLSN INTO SUN. FOR TDAY...THE SECOND SHRTWV IN ONTARIO/ACCOMPANYING ARCTIC COLD FNT WL BE THE MAIN INFLUENCE ON WX ACRS CWA AS FIRST SHRTWV/ACCOMPANYING DYNAMICS WL BE PASSING TO THE S INTO THE LOWER LKS BY 12Z. IN ITS WAKE...THE ONTARIO SHRTWV WL DIG ACRS THE FA WITH ARCTIC COLD FROPA SOON AFT 12Z OVER THE NW AND ARND 18Z OVER THE SE. STILL EXPECTING A PD OF LK ENHANCED HEAVIER SHSN TO ACCOMPANY THE ARRIVAL OF THIS FEATURE OVER AT LEAST THE ZNS NEAR LK SUP AS GUIDANCE SHOWS DPVA/ H85-5 QVECTOR CNVGC/UPR DVGC/DEEP MSTR LINGERING UNTIL DYNAMICS/DEEP MSTR PASS TO THE E AFT 18Z. THE PRESENCE OF SHARP UVV WITHIN THE PRIME SN GROWTH LYR ALSO SUGS A PD OF HEAVY SN. CYC NLY FLOW PROGGED TO INCREASE IN THE WAKE OF THE FNT...WITH H925 WINDS RISING TO 35-40KT PRODUCING STRONG CAD/LLVL DESTABILIZATION. THESE STRONG WINDS WILL FRAGMENT THE SNOW FLAKES INTO A MORE POWDERY SN WITH ARRIVAL OF COLDER/DRIER AIR IN THE AFTN. THE RESULT WILL BE A MORE EFFICIENT REDUCTION IN VSBY...WITH WDSPRD BLSN EVEN AFT THE SN INTENSITY BEGINS TO DIMINISH. LK ENHANCED SN WL EVOLVE TO PURE LES BY LATER IN THE DAY AS H85 TEMPS BOTTOM OUT ARND -18C OVER LK SUP BY 00Z SUN. THE STRONG NNW WINDS...STRONGEST OVER THE CNTRL ZNS...WL PUSH THE SHSN FARTHER INLAND INTO DELTA/SRN SCHOOLCRAFT COUNTIES. OTRW...EXPECT HI TEMPS IN THE MRNG OVER THE W HALF...WITH THE MERCURY FALLING OFF IN THE AFTN WITH ARRIVAL OF COLDER AIR. LOOK FOR PURE LES TNGT WITH RISING HGTS/DNVA/H85-5 QVECTOR DVGC IN WAKE OF DEPARTING SHRTWV/SFC LO. THE INTENSITY OF THE LES/BLSN OVER THE W SHOULD DIMINISH THRU THE NGT WITH THE ARRIVAL OF MUCH DRIER AIR FM THE NW AND APPROACH OF HI PRES RDG AS INVERSION HGTS FCST TO LOWER TO 3K FT DURING THE NGT FM IWD-CMX. BUT STILL EXPECT HI SN/WATER RATIOS THROUGH THE END OF THE EVENT OVER THE W WITH TEMPS WITHIN THE INCRSGLY SHALLOW MOIST LYR ARND A FAVORABLE TEMP OF -15C...ESPECIALLY WITH DIMINISHING WINDS/SN FLAKE FRAGMENTATION. BLIZZARD CONDITIONS OVER ALGER/NRN SCHOOLRAFT COUNTY SHOULD EASE AFT THE EVNG WITH H925 WINDS FCST TO DIMINISH TO ARND 25 KT BY 12Z SUN. LES BANDS SHOULD CONTINUE TO DRIFT FAR INTO DELTA/SRN SCHOOLCRAFT ZNS. OTRW...LONGER FETCH LENGTH ACRS ERN LK SUP WL MITIGATE IMPACT OF DRYING SOMEWHAT. LES CHART WOULD SUG 3-6 INCHES OF SN THRU THE NGT OVER THE E...WITH THE HEAVIER AMTS MOST LIKELY OVER ALGER/NRN SCHOOLCRAFT IN MOST PERSISTENT...FOCUSED LLVL CNVGC SHOWN BY NAM12/LOCAL HI RES WRF-ARW ON E EDGE OF LAND BREEZE OFF THE INTERIOR W HALF. WL TEND TOWARD THE LO END OF MOS GUIDANCE FOR MIN TEMPS FCST CONSIDERING INTENSITY OF THIS SHRTWV/DRYNESS OF AIR UPSTREAM. GOING HEADLINES SEEM TO HAVE THE SITUATION IN HAND FOR TDAY...BUT OPTED TO END THE WRNGS BY 00Z SUN OVER THE W ONCE STRONGEST WINDS (H925 WINDS ABV 25 KTS) ARE FCST TO DIMINISH FOLLOWING PASSAGE OF PRES RISE MAX TO THE SE. WL MAINTAIN GOING HEADLINES AS IS FOR THE E HALF. LES WL DIMINISH W-E ON SUN WITH ARRIVAL OF HI PRES RDG UNDER CONTINUED RISING HGTS. AS LLVL FLOW BACKS AHEAD OF THIS FEATURE... THE LES OVER THE E WL TEND TO SHIFT TO THE E BUT END COMPLETELY FM MQT AND W. HOWEVER...LARGER SCALE NAM/GFS MIGHT BE TOO AGGRESSIVE WITH THIS SHIFT OVER THE E CONSIDERING STRONGER LLVL CNVGC SHOWN BY HIER RES CNDN/WRF-ARW RUNS TO BE MORE PERSISTENT OVER ALGER/NRN SCHOOLCRAFT WITH LAND BREEZE OFF ONTARIO HOLDING UP THE PROGRESS. BUT SINCE WINDS/BLSN WL NO LONGER BE AN ISSUE...WL NOT EXTEND GOING HEADLINE EXPIRATION OF 15Z FOR THESE ZNS. OTRW...SUN WL BE ANOTHER VERY COLD DAY UNDER ARRIVING RDG AXIS AND 850 MB THERMAL TROF WITH H85 TEMPS RANGING FM ABOUT -15C OVER THE W TO -18C OVER THE E BY 00Z MON. MAX TEMPS SHOULD REMAIN IN THE TEENS AT MOST SPOTS EVEN THOUGH THERE WL BE SOME SUNSHINE OVER THE W AND CNTRL BEFORE MORE HI CLDS AHEAD OF NEXT SHRTWV APRCHG FM THE W INVADE LATER IN THE DAY. AS FLOW BACKS TO MORE SSW ON SUN NGT AHEAD OF INCOMING SHRTWV FM THE PLAINS...LINGERING LES OFF LK SUP WL DIMINISH AND END OVER THE E WHILE MID CLD THICKENS WITH DVLPG ISENTROPIC LIFT SHOWN ON THE 275K-285K SFCS (H8 THRU H7). GFS AND ESPECIALLY THE NAM SHOW SHARPER ISENTROPIC LIFT/H85-5 QVECTOR CNVGC PASSING TO THE S OF THE FA. WITH SUPPORT FM THE CNDN MODEL AND NCEP PREFERENCE...WL FOLLOW THE GFS/CNDN SOLN MOST CLOSELY. THESE MODELS SUG A SOMEWHAT HIER POP OVER THE SRN TIER...WITH BOTH ACTUALLY SHOWING SOME UPR DVGC IN LEFT EXIT OF SUPPORTING UPR JET STREAK. LOOKS LIKE MUCH OF THESE DYNAMICS WL BE NECESSARY TO SATURATE INITIALLY DRY AIRMASS...SO WL KEEP POPS IN THE CHC RANGE (20 OVER THE N TO 50 ACRS THE S) EXCEPT OVER SRN MNM COUNTY (60 THERE). ONE OTHER INTERESTING ASPECT OF THE FCST IS THE POTENTIAL FOR AN LES BAND TO DVLP OVER LK MI AND PUSH INTO THE ERN ZNS ON THE HEELS OF A SSW WIND AND H85 TEMPS ARND -13C OVER NRN LK MI AT 12Z MON. WL MAINTAIN GOING HIER POPS TO REFLECT THIS POTENTIAL DOWNWIND OF LK MI. DIMINISHED POPS A BIT ON MON AFTN AS GFS/CNDN SHOW BETTER DYNAMICS SHIFTING TO THE E AND SOME DRYING ALF. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... ARCTIC FRONT ON VERGE OF PUSHING THROUGH KEWEENAW. AS THE FRONT SWEEPS THROUGH THE REST OF UPPER MICHIGAN THROUGH EARLY AFTN...EXPECT PERIOD OF HVY LAKE ENHANCED SHSN AND BLSN AS WINDS SHIFT SHARPLY TO STRONG NRLY. VLIFR CONDITIONS IN SHSN/BLSN WILL OCCUR AT BOTH SITES...ALREADY HAPPENING AT CMX...AND DUE INTO SAW EARLY THIS AFTN. EVENTUALLY...IMPROVEMENT TO LIFR EXPECTED...BUT THIS MAY TAKE A WHILE AS STRONG WINDS/BLSN HANG ON INTO THE EARLY EVENING. FURTHER IMPROVEMENT TO IFR AT KCMX AND TO MVFR AT KSAW SHOULD OCCUR LATER TONIGHT AS AIRMASS BECOMES DRIER...CAUSING SHSN TO DIMINISH...AND WINDS DECREASE...RESULTING IN LESS BLSN. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... STRONG COLD FRONT PLOWING THROUGH ALONG WITH SFC LOW DEEPENING JUST EAST OF LK SUPERIOR RESULTS IN GALES 40-45 KNOTS FOR THE E 2/3 OF LAKE SUPERIOR THROUGH TONIGHT. WINDS DIMINISH BY SUNDAY AS HIGH PRESSURE MOVES ACROSS THE GREAT LAKES. SRLY WINDS ON MONDAY AHEAD OF LOW PRESSURE TROUGH SHOULD REACH 30 KNOTS...MAINLY OVER E 1/2 OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ084. BLIZZARD WARNING FROM 1 PM THIS AFTERNOON TO 10 AM EST SUNDAY FOR MIZ006-085. BLIZZARD WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ001-003. WINTER STORM WARNING UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR MIZ002-009. WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 10 AM EST SUNDAY FOR MIZ007. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ004. WINTER STORM WARNING UNTIL 7 AM EST SUNDAY FOR MIZ005. WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST SUNDAY FOR MIZ013-014. LAKE SUPERIOR... GALE WARNING UNTIL 7 AM EST SUNDAY FOR LSZ248>251-265>267. GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LSZ263-264. GALE WARNING UNTIL 1 AM EST SUNDAY FOR LSZ242>245. GALE WARNING UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR LSZ241. LAKE MICHIGAN... GALE WARNING FROM 4 PM THIS AFTERNOON TO 1 AM EST SUNDAY FOR LMZ221-250. && $$ UPDATE...AJ DISCUSSION...KC AVIATION...JLA MARINE...JLA mi