AREA FORECAST DISCUSSION..CORRECTED TIME NATIONAL WEATHER SERVICE TALLAHASSEE FL 210 PM EST MON DEC 4 2006 ...FIRST SIGNIFICANT FREEZE OF THE SEASON LATE TONIGHT AND EARLY TUESDAY MORNING... .SYNOPSIS... WATER VAPOR/RUC H5 COMPOSITE ANIMATION SHOWS THE SHORT WAVE TROUGH EXITING THE EAST COAST...WITH THE MEAN LONG WAVE TROUGH IN PLACE OVER THE ERN 2/3 OF THE CONUS. MORE SHORT WAVE ENERGY IS POISED TO MOVE FROM THE PACIFIC NW INTO THE NRN ROCKIES. CLOSER TO HOME... SURFACE RIDGE AXIS EXTENDS FROM THE OH VALLEY TO TX. REINFORCEMENT OF CANADIAN AIRMASS IS MOVING INTO FAR SOUTH FL. VERY DRY AIR (DEW POINTS IN THE TEENS) CONTINUES TO SPREAD SEWD THROUGH AL...SW GA AND THE FL PANHANDLE. TEMPS RANGE FROM 48 AT DOTHAN AL TO 62 AT CROSS CITY FL. PRESSURE GRADIENT REMAINS RATHER TIGHT WITH NORTHERLY WINDS SUSTAINED NEAR 15 MPH. GUSTS RANGED FROM 16 TO 25 MPH ACROSS MUCH OF THE REGION THIS AFTN. OVER THE MARINE AREA...WINDS HAVE DIMINISHED SLIGHTLY...19-22 KTS WITH GUSTS TO 25 KTS. SEAS RANGE FROM 7-9 FT OFFSHORE TO 3-6 FT NEAR SHORE. && .SHORT TERM (TONIGHT THROUGH WEDNESDAY NIGHT)... MEAN MID/UPPER TROUGH OVER THE ERN HALF OF THE CONUS WILL BE REINFORCED BY A SERIES OF SHORT WAVE TROUGHS PLOWING SEWD FROM CANADA DURING THE PERIOD. AT THE SURFACE...THE STRONG RIDGE WILL GRADUALLY WEAKEN AS IT SLIDES EWD ACROSS THE DEEP SOUTH...RESULTING IN AN NORTH-NORTHEAST FLOW THROUGH TUESDAY...THEN BECOME MORE EASTERLY ON WEDNESDAY. TONIGHT...FIRST WIDESPREAD FREEZE OF THE SEASON IS STILL EXPECTED ACROSS THE REGION. THE PAST TWO MOS CYCLES HAS SHOWN SLIGHTLY WARMER LOWS FOR TONIGHT. THUS HAVE SCALED BACK THE HARD FREEZE WARNING AREA TO INCLUDE A SMALL PORTION OF SERN AL AND THE INLAND FL PANHANDLE WHERE MIN TEMPS OF 25 DEGREES OR LOWER FOR AT LEAST TWO HOURS ARE EXPECTED. A GENERAL FREEZE WARNING IS PREDICTED FOR THE REMAINDER OF THE CWFA WITH MIN TEMPS FROM 26 TO 32 BY SUNRISE TUESDAY. WITH THE DRY AIR IN PLACE...THERE WILL BE NO FROST CONCERNS. TUESDAY/TUESDAY NIGHT...THE RIDGE SLIDES THROUGH AL/GA DURING THE DAY WITH DIMINISHING WINDS. WITH WEAKER COLD AIR ADVECTION AND FULL INSOLATION...EXPECT HIGH TEMPS TO BE ABOUT 5 DEGREES WARMER THAN TODAY...WHICH IS STILL BELOW NORMAL FOR EARLY DECEMBER. THE RIDGE MOVES JUST EAST OF THE AREA TUESDAY NIGHT...BUT IT SHOULD STILL BE IN CLOSE PROXIMITY TO PROVIDE ENOUGH RADIATIONAL COOLING FOR LOWS TO FALL BELOW FREEZING (A LIGHT FREEZE) EARLY WEDNESDAY MORNING FOR MOST INLAND AREAS. IT WILL BE ABOVE FREEZING NEAR THE COAST. SMALLER TEMP/DEW POINT SPREADS SUGGEST THE POSSIBILITY OF PATCHY FROST IN THE NORMALLY COLDER INLAND AREAS. WEDNESDAY/WEDNESDAY NIGHT...WITH THE RIDGE EAST OF THE REGION...WARM AIR ADVECTION RETURNS AND HIGHS WILL MODERATE TO NORMAL VALUES. A WEAK SURFACE FRONT MOVES ACROSS THE ERN STATES WEDNESDAY NIGHT/EARLY THURSDAY MORNING. MIN TEMPS WILL AVERAGE ABOUT 10 DEGREES WARMER THAN TUESDAY NIGHT. && .LONG TERM (THURSDAY THROUGH SUNDAY)... GLOBAL MODELS IN BETTER AGREEMENT WITH STRONG RIDGE ACROSS ROCKIES AND TROUGH OVER ERN TWO-THIRDS OF CONUS DOWN INTO THE SE STATES. ONE SHORTWAVE AFFECTS THE GULF OF MEXICO AND SRN U.S. WITH ANOTHER ONE DIVING SEWD OVER THE E CENTRAL U.S. ON THURSDAY. AT SURFACE... HIGH PRESSURE SPREADS DOWN GREAT PLAINS. WAVE OF LOW PRESSURE DEVELOPS IN THE WESTERN GULF THURSDAY NIGHT AND THEN SLOWLY MOVING EAST. HOWEVER...A STRONG HIGH AND ASSOCD RIDGE BEGIN TO DROP RAPIDLY SEWD PROVIDING A REINFORCEMENT OF COOLER/DRIER AIR LATE THURSDAY THROUGH EARLY FRIDAY INTO NE GULF LIKELY KEEPING ANY MOISTURE CONFINED OVER THE WESTERN AND CENTRAL GULF. THIS LEAVES MUCH COLDER THAN NORMAL AIR OVER NE GULF INTO SATURDAY AND WOULD NOT BE SURPRISED TO SEE FREEZING TEMPS SAT MORNING. BY SATURDAY AFTERNOON...AT UPPER LEVELS...TROUGH EXITS EAST INTO ATLC REPLACED BY BUILDING RIDGE. LOW LEVEL NORTHERLY FLOW VEERS TO EASTERLY AND TEMPERATURES BEGIN TO MODERATE TO AOA NORMAL BY SUNDAY. THE GFS HAS TRENDED STRONGER WITH THE RIDGE RESULTING IN COOLER TEMPS. && .MARINE... A TIGHT PRESSURE GRADIENT WILL KEEP WINDS AND SEAS AT SMALL CRAFT ADVISORY CRITERIA TONIGHT...ESPECIALLY OVER THE OFFSHORE WATERS. AS THE RIDGE OF HIGH PRESSURE MOVES CLOSER...WINDS AND SEAS WILL BEGIN TO DIMINISH OVERNIGHT AND INTO TUESDAY. HIGH PRESSURE WILL DOMINATE THE WATERS THROUGH MID WEEK. A DRY COLD FRONT WILL MOVE THROUGH THE WATERS THURSDAY NIGHT AND FRIDAY REINFORCING THE COLD AIRMASS. IN ITS WAKE...STRONG HIGH PRESSURE BUILDS INTO THE SOUTHEAST WITH WINDS AND SEAS INCREASING ONCE AGAIN. && .AVIATION... BASICALLY A WIND FORECAST. SKIES WILL BE CLEAR...WITH LITTLE CHANCE FOR ANY REDUCED VSBYS TOMORROW MORNING. WINDS THIS AFTN WILL BE NORTH TO NORTH NORTHWEST WITH POSSIBLE GUSTS NEAR 20 KTS. WINDS WILL BECOME NEAR CALM AT MOST TERMINALS TONIGHT. TOMORROW...EXPECT NORTHERLY WINDS LESS THAN 10 KTS. && .FIRE WEATHER... RED FLAG WARNINGS WILL VERIFY THIS AFTN FOR OUR FL AND GA ZONES DUE TO LONG DURATIONS OF LOW RH AND SUSTAINED WINDS NEAR 15 MPH. THE EXCEPTION WOULD BE SERN AL WHERE THE KBDI VALUES REMAIN BELOW 500. FOR TUESDAY...WITH THE RIDGE CLOSER TO THE REGION...WINDS WILL BE LIGHTER THAN TODAY. WE STILL EXPECT LONG DURATIONS OF LOW RH FOR THE FL AND GA ZONES AND HAVE UPGRADED THE WATCHES TO RED FLAG WARNINGS. FOR SERN AL...WILL KEEP THE WATCH IN EFFECT AND LET THE MID SHIFT EVALUATE THE SITUATION. NO CONCERNS FOR WEDNESDAY. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 27 63 31 68/ 00 00 05 10 PANAMA CITY 31 63 40 67/ 00 00 05 10 DOTHAN 26 59 33 65/ 00 00 05 10 ALBANY 27 60 31 67/ 00 00 05 10 VALDOSTA 28 62 33 69/ 00 00 05 10 CROSS CITY 31 66 37 71/ 00 00 05 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...HARD FREEZE WARNING IN EFFECT FROM LATE TONIGHT THROUGH EARLY TUESDAY MORNING FOR COFFEE...DALE AND GENEVA COUNTIES. FREEZE WARNING IN EFFECT FROM LATE TONIGHT THROUGH EARLY TUESDAY MORNING FOR HENRY AND HOUSTON COUNTIES. RED FLAG WARNING FOR THE REMAINDER OF THIS AFTN. FIRE WEATHER WATCH FROM LATE TUESDAY MORNING THROUGH TUESDAY AFTN. GA...FREEZE WARNING IN EFFECT FROM LATE TONIGHT THROUGH EARLY TUESDAY MORNING. RED FLAG WARNING THROUGH EARLY THIS EVENING. RED FLAG WARNING TUESDAY AFTN. FL...HARD FREEZE WARNING IN EFFECT FROM LATE TONIGHT THROUGH EARLY TUESDAY MORNING FOR INLAND WALTON AND HOLMES COUNTIES. FREEZE WARNING IN EFFECT FROM LATE TONIGHT THROUGH EARLY TUESDAY MORNING FOR THE REMAINING COUNTIES. RED FLAG WARNING THROUGH EARLY THIS EVENING. RED FLAG WARNING FROM LATE TUESDAY MORNING THROUGH EARLY TUESDAY EVENING. GM...SMALL CRAFT ADVISORY THROUGH LATE TONIGHT OFFSHORE LEGS. && $$ AVIATION...WATSON SHORT TERM/MARINE/FIRE WEATHER...JAMSKI LONG TERM...BLOCK fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1030 AM CST MON DEC 4 2006 .DISCUSSION... UPDATED THE FORECAST MORE MORE CLOUD COVER AND STRONGER WINDS TODAY. KEPT HIGHS IN THE MID TO UPPER 20S OVER THE SNOW PACK AND LOWER 30S ACROSS SE IL. 16Z/10 AM SURFACE ANALYSIS SHOWS STRONG 1041 MB POLAR HIGH PRESSURE OVER EAST TEXAS AND RIDGING NE ACROSS KY/OHIO VALLEY. WEAK 1017 MB LOW PRESSURE OVER WESTERN LAKE SUPERIOR WITH ITS ASSOCIATED FRONT EXTENDING SW ACROSS CENTRAL IA. ALOFT A BROAD UPPER LEVEL TROF WAS ACROS THE EASTERN 2/3RDS OF THE U.S. WITH A DECENT SHORT WAVE NEAR THE MN/WI/IA BORDER. OVERCAST MID LEVEL CLOUDS OF 6 TO 8 KFT SINKING QUICKLY SOUTHWARD TOWARD I-70 LATE THIS MORNING WITH AREAS ALONG AND SOUTH OF I-70 ENJOYING SUNNY SKIES. FLURRIES OCCURRING IN EAST/WEST BAND FROM LACON TO PONTIAC TO NW INDIANA. SW WINDS PICKED UP TO BREEZY LEVELS BY MID MORNING AT 15 TO 25 MPH AND GUSTS TO 32 MPH IN EAST CENTRAL IL AT CHAMPAIGN AND DANVILLE. TEMPS WERE IN THE UPPER TEENS AND LOWER 20S EXCEPT 24 TO 28F FROM MATTOON SOUTH. BREEZY WINDS GIVING WIND CHILLS AS COLD AS THE SINGLE DIGITS OVER THE SNOW PACK NW OF MATTOON. RUC AND NAM/WRF TAKE SHORT WAVE SE ACROSS WI/LOWER MI THIS AFTERNOON AND EVENING KEEPING BEST CHANCES OF LIGHT SNOW AND FLURRIES IN THE GREAT LAKES REGION NE OF CENTRAL IL. LOW LEVELS BELOW 700 MB VERY DRY PER ILX/DVN 12Z SOUNDINGS SO TOUGH TO GET EVEN FLURRIES IN NE AREAS. THIS FEATURE THOUGH WILL BRING ABOUT A 6 HOUR PERIOD OF MID LEVEL CLOUDS TODAY...WHICH MOVE SPREAD INTO SE IL DURING MIDDAY WHILE DECREASING FROM THE IL RIVER VALLEY NW BY MID AFTERNOON. BREEZY SW WINDS TO SETTLE DOWN TOWARD EVENING AS HIGH PRESSURE OVER EAST TX/LA NOSES RIDGES BACK NORTH INTO IL TONIGHT. TEMPS MAY CLIMB ANOTHER 3 TO 5 DEGREES WITH ALL THE MID LEVEL CLOUDS AND WIDESPREAD SNOW PACK WITH STILL 6 TO 12 INCH SNOW DEPTH FROM SPRINGFIELD TO ROANOKE NW. && .PREV DISCUSSION... NOT MANY CONCERNS WITH THIS FORECAST PACKAGE...AS MIDWEST CONTINUES TO BE UNDER THE INFLUENCE OF NORTHWESTERLY UPPER FLOW PATTERN. BOTTOM LINE WILL BE COLDER AND DRIER THAN NORMAL CONDITIONS FOR MUCH OF THE WEEK. SHORT TERM...TODAY THROUGH WEDNESDAY... NEXT CLIPPER SYSTEM OF INTEREST CLEARLY EVIDENT IN WATER VAPOR IMAGERY ACROSS NORTHERN MINNESOTA. MODELS INITIALIZED THIS FEATURE QUITE WELL...WITH BOTH THE NAM-WRF AND GFS TRACKING IT INTO THE GREAT LAKES TODAY. PLENTY OF MID AND HIGH-LEVEL CLOUDS IN ADVANCE OF THE SYSTEM WILL ADVECT INTO CENTRAL ILLINOIS...RESULTING IN PARTLY TO MOSTLY CLOUDY SKIES FOR MUCH OF THE DAY. AREA FORECAST SOUNDINGS REMAIN QUITE DRY...SO THINK ANY SNOW FLURRIES WILL REMAIN FURTHER NORTH. WAA AHEAD OF THE SYSTEM WILL BOOST 850MB TEMPS INTO THE -4 TO -7C RANGE...HOWEVER INCREASED CLOUD COVER WILL HOLD TEMPS BACK. GIVEN THE TREND OF THE PAST FEW DAYS...WILL ONCE AGAIN UNDERCUT THE COLDEST NUMERIC GUIDANCE BY A COUPLE OF DEGREES...WITH HIGHS RANGING FROM THE MIDDLE 20S ACROSS THE SNOW-PACK...TO THE LOWER 30S SOUTH OF I-70. SKIES SHOULD RAPIDLY CLEAR FROM WEST TO EAST THIS EVENING...AS SUBSIDENCE IN THE WAKE OF THE WAVE LEADS TO MARKED MID-LEVEL DRYING. WITH CLEAR SKIES AND LIGHT WINDS...ANOTHER COLD NIGHT IS IN STORE WITH TEMPS DIPPING BACK INTO THE SINGLE DIGITS ALONG AND WEST OF I-55. WAA INCREASES ON TUESDAY...AS NEXT CLIPPER SYSTEM BEGINS TO APPROACH FROM THE NORTHWEST. WITH 850MB TEMPS PROGGED TO CLIMB ABOVE 0C...HIGH TEMPS SHOULD TOP OUT IN THE MIDDLE TO UPPER 30S ACROSS SNOW-FREE AREAS. HOWEVER...TEMPS WILL LIKELY HOVER IN THE UPPER 20S AND LOWER 30S ACROSS THE SNOW-COVERED ILLINOIS RIVER VALLEY. NEXT CLIPPER STILL ON TRACK TO SWING THROUGH THE REGION LATE TUESDAY NIGHT INTO WEDNESDAY MORNING. 00Z 4 DEC MODELS A BIT MORE ROBUST WITH MOISTURE PROFILES THAN IN PREVIOUS RUNS...WITH THE GFS SUGGESTING SOME LIGHT QPF. WILL THEREFORE MAINTAIN THE CURRENT CHANCE FOR FLURRIES...BEGINNING ACROSS THE NW CWA AFTER MIDNIGHT TUESDAY...SPREADING EVERYWHERE WEDNESDAY. LONG TERM...THURSDAY THROUGH SUNDAY... MEDIUM RANGE MODELS CONTINUE TO ADVERTISE A SIGNIFICANT PATTERN CHANGE BEGINNING BY THE END OF THE WEEK. BOTH ECMWF/GFS SHOW RISING HEIGHTS ACROSS THE MIDWEST...AS UPPER RIDGING BUILDS ACROSS THE PLAINS. WITH RUN-TO-RUN CONSISTENCY...CONFIDENCE IS NOW GROWING THAT TEMPS WILL RETURN TO NEAR NORMAL BY NEXT WEEKEND. THIS WILL MEAN HIGHS AROUND 40 DEGREES...WITH COOLER READINGS OVER THE PERSISTENT SNOW-COVER ACROSS THE ILLINOIS RIVER VALLEY. MODELS ARE ALSO SHOWING A WEAK SYSTEM APPROACHING FROM THE SOUTHWEST BY NEXT SUNDAY...AS UPPER FLOW TRIES TO TRANSITION TO SOUTHWESTERLY. GFS IS BRINGING LIGHT PRECIP INTO THE AREA SUNDAY...HOWEVER AM NOT BUYING INTO THIS JUST YET...OPTING INSTEAD TO MAINTAIN DRY FORECAST WITH AN INCREASE IN CLOUD COVER. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ HUETTL/BARNES il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 649 PM EST MON DEC 4 2006 .DISCUSSION... AVIATION...7PM MON-7PM TUE A BAND OF AC AT AROUND 10000 FEET WAS SHOWN ON SATELLITE PICTURES AND SURFACE OBSERVATIONS FROM SOUTHERN OHIO...SOUTHERN INDIANA...AND INTO NORTHERN KENTUCKY. THIS BAND SHOULD MOVE SOUTHEAST...AND REACH ALL THREE TAF SITES BY AROUND 3Z. WENT WITH FEW100 AS THE CLOUDS MOVE IN...THEN BKN AS THE BAND OF CLOUDS MOVES OVER THE AREA. MODEL SOUNDINGS AND RH PROFILES INDICATE SOME SC BETWEEN 2 AND 3 THOUSAND FEET FORMING TOWARD MORNING. THIS SHOULD BE SCT AT JKL...AND FEW IN COVERAGE AT LOZ AND SME. THESE SHOULD WORK THEIR WAY OUT OF THE AREA BY AROUND 12Z. AFTER 12Z TUESDAY...EXPECT VFR CONDITIONS WITH A FEW CI MOVING ACROSS THE AREA. && .PREV DISCUSSION... 400 PM EST MON DEC 4 2006 DISCUSSION... SHORT TERM...TUESDAY THROUGH WEDNESDAY... MODELS IN PRETTY GOOD AGREEMENT...SO WENT WITH GFS FOR CONSISTENCY. FOR TONIGHTS TEMPERATURES...BASED ON LAST NIGHTS LOW TEMPERATURES AND RATE OF DECREASE...ANALYSIS OF -8 TO -11 DEGREE C AIR MASS AT 850 HPA...AND LATEST MOS NUMBERS...WENT A DEGREE COOLER THAN COOLEST MOS TEMPS FOR TONIGHTS LOWS ACROSS THE BOARD. INSPITE OF INCREASING CLOUD COVER LAST NIGHT...TEMPS WERE STILL ABLE TO DROP FAIRLY STEADILY...AS MOST OF THE CLOUD COVER WAS MID TO HIGH LEVEL STUFF. ANTICIPATE THE SAME SCENARIO TONIGHT...SO WENT A BIT COOLER WITH TEMPS. WITH LIGHT WINDS AND INCREASING CLOUDS...NOT ANTICIPATING MUCH IN THE WAY OF A RIDGE VALLEY SPLIT TONIGHT. WENT WITH A COMPROMISE BETWEEN MAV/MET MOS FOR TUESDAYS HIGHS. TWO THINGS WILL BE AT WORK TOMORROW FOR TEMPS. FIRST WILL BE DECENT SOUTHWESTERLY FLOW AND THE SECOND BEING HIGH CLOUDS MOVING IN FROM THE WEST. A SERIES OF CLIPPER SYSTEMS WILL TRAVERSE THE AREA THIS WEEK...BRINGING WITH THEM MID AND HIGH LEVEL CLOUDS. THE CLOUDS SHOULD ACT TO KEEP TEMPS FROM GETTING AS WARM AS THE WARMEST MOS...WHICH IS THE MET...BUT THE SOUTHWESTERLY FLOW SHOULD ALLOW TEMPS TO STAY UP JUST A BIT MORE THAN THE COOLER MAV MOS. OVERALL TUESDAY NIGHTS LOWS ARE A BLEND OF MAV AND MET MOS AT LONDON...A DEGREE WARMER THAN WARMEST MOS AT JACKSON DUE TO CLOUD COVER AND WINDS...AND A BIT COOLER THAN THE LOWEST MOS AT SME DUE TO ITS VALLEY LOCATION AND WIND FETCH ACROSS LAKE CUMBERLAND. IT DOESNT LOOK LIKE THERE WILL BE MUCH IN THE WAY OF CLOUD COVER SOUTH OF THE HAL ROGERS PARKWAY TOMORROW NIGHT...SO FELT A BIT COOLER TEMPS WERE WARRANTED DOWN THERE. WITH AN INCREASE IN BOTH CLOUD COVER AND SOUTHWESTERLY FLOW WEDNESDAY...LOOKING FOR MODERATED TEMPERATURES AND A SMALLER DIURNAL INCREASE IN TEMPS THAN NORMAL. WITH MAV A BIT TOO COOL AT JACKSON...WENT WITH A BLEND OF THE MAV/MOS...WITH A BIAS TOWARD THE MAV. WENT A BIT COOLER THAN LOWEST MOS FOR WED HIGHS AT LOZ AND SME. WENT PRETTY CLOSE TO MAV MOS FOR WEDNESDAY NIGHT LOWS...GOING AT OR JUST ABOVE MAV MOS...TAKING INTO CONSIDERATION THE MOSTLY CLOUDY SKIES THAT WILL ACCOMPANY A CLIPPER SYSTEM AS IT MOVES OFF TO THE EAST. WEDNESDAY NIGHTS CLIPPER WILL HAVE A BIT MORE MOISTURE WITH IT THAN THE ONES THAT HAVE TRAVERSED THE AREA OVER THE WEEKEND. HOWEVER...THIS SYSTEM STILL ISNT ALL THAT IMPRESSIVE AND IT WILL BE MOVING BY RATHER QUICKLY. MODEL CROSS SECTIONS SHOWING ABOUT A 12 HOUR PERIOD WITH GOOD MOISTURE. INITIALLY THROUGH THE DEPTH OF THE ATMOSPHERE...FROM 0Z THU UNTIL 8Z OR SO...WITH MUCH SHALLOWER BUT PERSISTENT LOW LEVEL MOISTURE IN PLACE AFTER 8Z. SHOULD NOT SEE MUCH MORE THAN SCATTERED LIGHT SNOW SHOWERS...ESPECIALLY CONSIDERING THE SPEED OF THE SYSTEM...THESE WILL GRADUALLY TAPER TO FLURRIES ASSOCIATED WITH THE CLOUDS TRAILING THE CLIPPER AS IT MOVES OFF TO THE NORTHEAST. MADE A FEW SLIGHT ADJUSTMENTS TO THE WINDS...GOING WITH A SLIGHT INCREASE IN SPEED AND VEERING TO THE WEST AS THE CLIPPER MOVES BY WEDNESDAY THURSDAY NIGHT. DEWPOINTS WERE IN GOOD SHAPE FOR THE MOST PART SO ONLY A FEW SLIGHT CHANGES WERE MADE THERE. MADE ADJUSTMENTS TO THE WEATHER AND QPF GRIDS TO ACCOUNT FOR CHANGES MADE TO POPS AND SKY COVER. FORECAST WILL BE OUT SHORTLY. EXTENDED...THURSDAY THROUGH MONDAY... ONLY A FEW MINOR CHANGES MADE IN THIS PORTION OF THE FORECAST. GFS AND ECMWF BOTH HANDLING LONG TERM SYNOPTIC PATTERNS PRETTY WELL. WITH SUPPORT FROM THE ECMWF...THE GFS SOLUTION LOOKED GOOD. YET ANOTHER CLIPPER SYSTEM WILL TRAVERSE THE REGION THURSDAY AFTERNOON INTO FRIDAY MORNING. BROKEN TO OVERCAST MIDDLE LEVEL CLOUD COVER AND A FEW SNOW SHOWERS WILL ACCOMPANY THIS FEATURE AS IT RACES OF TO THE EAST. THIS DISTURBANCE WILL GRADUALLY GIVE WAY TO CANADIAN HIGH PRESSURE FRIDAY...SATURDAY...AND MOST OF SUNDAY. ANOTHER UPPER LEVEL DISTURBANCE WILL MOVE BY THE AREA SUNDAY NIGHT INTO MONDAY. A CORRESPONDING INCREASE IN CLOUDINESS IS ANTICIPATED SUNDAY EVENING AS THIS FEATURE APPROACHES. DAYTIME HIGH TEMPERATURES SEEMED A BIT COOL...SO THESE WERE INCREASED SLIGHTLY BASED UPON SKY COVER FORECAST AND 12Z MEXMOS DATA. WITH PLENTY OF COLD DRY AIR IN PLACE...ANTICIPATE TEMPERATURES WILL WARM A BIT FASTER THAN PREVIOUSLY FORECAST DURING THE WEEKEND. WENT A BIT WARMER WITH SUNDAY HIGH TEMPS AS WELL...BUT STILL BELOW MOS NUMBERS DUE TO INCREASE IN CLOUD COVER ANTICIPATED. OVERNIGHT LOWS WERE INCREASED A BIT AS WELL FOR SATURDAY NIGHT AND SUNDAY...ACCOUNTING FOR INCREASED SOUTHERLY FLOW AND CLOUD COVER. REST OF FORECAST WAS IN GOOD SHAPE. WINDS HAVE SHIFTED TO THE SW AND TEMPS HAVE WARMED TO THE POINT THAT THE FLURRIES HAVE ENDED. RADAR STILL SHOWING RETURNS FROM OUR ERN COUNTIES BUT CALLS CONFIRM THAT THIS IS A DISSIPATING...UPSLOPE CLOUD DECK AT ABOUT 2K. COLD START TO DAY AND PREVAILING CLOUDS THIS MORNING SHOULD KEEP TEMPS SOMEWHAT SUPPRESSED GIVEN LOW ANGLE OF SUN. 450 AM EST MON DEC 4 2006 A SHORT WAVE IS CURRENTLY PASSING ACROSS THE COMMONWEALTH AND IS STRONG ENOUGH TO GENERATE A BAND OF LOW CLOUDS AND FLURRIES ACROSS PORTIONS OF THE OHIO VALLEY THIS MORNING. MOST IF NOT ALL OF THIS ACTIVITY WILL HAVE PUSHED EAST OUT OF EASTERN KENTUCKY BY MID DAY. HENCE... HAVE INCLUDED FLURRIES IN THE FCST PACKAGE FOR THIS MORNING. OTHERWISE...NO MAJOR CHANGES TO THE FCST PACKAGE. THURSDAYS SHORTWAVE...AND CLIPPER SYSTEM HAS COME IN A BIT STRONGER WITH THE 0Z RUN. FCST SOUNDINGS AND TIME HEIGHT SECTIONS ARE SHOWING MORE MOISTURE AND A MORE FAVORABLE ENVIRONMENT FOR DENDRITIC GROWTH AS WELL. THEREFORE KEPT THE SLIGHT POP IN THE FORECAST FOR WEDNESDAY NIGHT AND EARLY THURSDAY. MADE SOME MINOR TWEAKS TO THE TEMPS FOR CCF PURPOSES. MOST SIGNIFICANT CHANGE WAS TO DROP TODAYS HIGH TEMPS A COUPLE OF DEGREES. WILL HAVE EXTRA CLOUD COVER TO DEAL WITH THROUGH THE MORNING AND COLD AIR ADVECTION THROUGH MOST OF THE DAY LIGHT HOURS. MODELS...MOS GUIDANCE DO HAVE WINDS SHIFTING QUICKLY TO THE SOUTHWEST LATE THIS AFTERNOON...INTO THE EVENING AHEAD OF THE NEXT WEAK CLIPPER SYSTEM. HOWEVER...THIS TAKES PLACE AFTER PEAK HEATING OF THE DAY. ALL THINGS CONSIDERED...FELT LOWER WAS THE WAY TO GO. 1059 PM EST SUN DEC 3 2006 SHORT TERM...REST OF TONIGHT... RADAR TRENDS IN INDIANA AND SOUTHWEST OHIO SHOW SOME FLURRIES ALONG THE H5 TROUGH AXIS/VORT MAX MOVING THROUGH. MODELS SHOW A LITTLE LESS MOISTURE AT 925 AND 900 MB IN OUR CWA WHICH WOULD INDICATE A LITTLE LESS CHANCE FOR FLURRIES...BUT I BELIEVE THERE COULD BE A FEW SNOWFLAKES WITH THE SC LAYER MOVING IN. ISSUED ANOTHER UPDATE TO ADD THESE TO THE FORECAST. KEPT THE FLURRIES OUT OF THE SOUTHERN COUNTIES OF THE CWA. SATELLITE ALSO SHOWS THE SC LAYER BECOMING MORE DEVELOPED TO OUR NORTHWEST. UPDATED TEXT FORECAST IS ALREADY ISSUED. 915 PM EST SUN DEC 3 2006 SHORT TERM...THE REST OF TONIGHT... AREA OF CI WITH SOME AC CONTINUES TO MOVE ACROSS THE AREA. ANOTHER NARROW BAND OF LOWER AC WAS MOVING IN FROM THE NORTHWEST AHEAD OF AN H5 TROUGH. THIS TROUGH WILL SWING THROUGH EASTERN KENTUCKY BETWEEN 6Z AND 10Z OVERNIGHT. LOOKING AT SATELLITE PICTURES AND SURFACE OBS...AN AREA OF SC WAS MOVING SOUTHEAST THROUGH INDIANA. THERE WERE EVEN A FEW FLURRIES REPORTED IN THE SURFACE OB...AND DEPICTED ON WEATHER SERVICE RADAR...NEAR IND. THE GFS IS SHOWING LOWER RH IN THE LOWER LEVELS AS COMPARED TO THE RUC AND THE WRF. ATTM...I BELIEVE THE HIGHER LOWER LEVEL RH/S SHOWN IN THE RUC AND WRF ARE MORE REASONABLE. HAVE DECIDED TO GO WITH PARTLY CLOUDY SKIES FOR THE ENTIRE NIGHT FOR EASTERN KENTUCKY. SOME OF THE SC OVER INDIANA SHOULD WORK ITS WAY INTO OUR CWA. THESE CLOUDS SHOULD BE MAINLY SCATTERED IN NATURE MOST OF THE NIGHT. ALSO OPENED UP A TEMPERATURE RANGE IN SOME AREAS OVERNIGHT. SHOULD BE A COLD NIGHT WITH LOWS 15 TO 20 WITH GOOD CAA AT 850 MB. 850 MB TEMPS SHOULD BE DROPPING FROM CURRENT VALUES OF AROUND -3 DEG C...TO AROUND -12 DEG C BY 7 AM MONDAY MORNING. UPDATED FORECAST PRODUCTS WILL BE OUT SOON. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WJM ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 400 PM EST MON DEC 4 2006 .DISCUSSION... SHORT TERM...TUESDAY THROUGH WEDNESDAY... MODELS IN PRETTY GOOD AGREEMENT...SO WENT WITH GFS FOR CONSISTENCY. FOR TONIGHTS TEMPERATURES...BASED ON LAST NIGHTS LOW TEMPERATURES AND RATE OF DECREASE...ANALYSIS OF -8 TO -11 DEGREE C AIR MASS AT 850 HPA...AND LATEST MOS NUMBERS...WENT A DEGREE COOLER THAN COOLEST MOS TEMPS FOR TONIGHTS LOWS ACROSS THE BOARD. INSPITE OF INCREASING CLOUD COVER LAST NIGHT...TEMPS WERE STILL ABLE TO DROP FAIRLY STEADILY...AS MOST OF THE CLOUD COVER WAS MID TO HIGH LEVEL STUFF. ANTICIPATE THE SAME SCENARIO TONIGHT...SO WENT A BIT COOLER WITH TEMPS. WITH LIGHT WINDS AND INCREASING CLOUDS...NOT ANTICIPATING MUCH IN THE WAY OF A RIDGE VALLEY SPLIT TONIGHT. WENT WITH A COMPROMISE BETWEEN MAV/MET MOS FOR TUESDAYS HIGHS. TWO THINGS WILL BE AT WORK TOMORROW FOR TEMPS. FIRST WILL BE DECENT SOUTHWESTERLY FLOW AND THE SECOND BEING HIGH CLOUDS MOVING IN FROM THE WEST. A SERIES OF CLIPPER SYSTEMS WILL TRAVERSE THE AREA THIS WEEK...BRINGING WITH THEM MID AND HIGH LEVEL CLOUDS. THE CLOUDS SHOULD ACT TO KEEP TEMPS FROM GETTING AS WARM AS THE WARMEST MOS...WHICH IS THE MET...BUT THE SOUTHWESTERLY FLOW SHOULD ALLOW TEMPS TO STAY UP JUST A BIT MORE THAN THE COOLER MAV MOS. OVERALL TUESDAY NIGHTS LOWS ARE A BLEND OF MAV AND MET MOS AT LONDON...A DEGREE WARMER THAN WARMEST MOS AT JACKSON DUE TO CLOUD COVER AND WINDS...AND A BIT COOLER THAN THE LOWEST MOS AT SME DUE TO ITS VALLEY LOCATION AND WIND FETCH ACROSS LAKE CUMBERLAND. IT DOESNT LOOK LIKE THERE WILL BE MUCH IN THE WAY OF CLOUD COVER SOUTH OF THE HAL ROGERS PARKWAY TOMORROW NIGHT...SO FELT A BIT COOLER TEMPS WERE WARRANTED DOWN THERE. WITH AN INCREASE IN BOTH CLOUD COVER AND SOUTHWESTERLY FLOW WEDNESDAY...LOOKING FOR MODERATED TEMPERATURES AND A SMALLER DIURNAL INCREASE IN TEMPS THAN NORMAL. WITH MAV A BIT TOO COOL AT JACKSON...WENT WITH A BLEND OF THE MAV/MOS...WITH A BIAS TOWARD THE MAV. WENT A BIT COOLER THAN LOWEST MOS FOR WED HIGHS AT LOZ AND SME. WENT PRETTY CLOSE TO MAV MOS FOR WEDNESDAY NIGHT LOWS...GOING AT OR JUST ABOVE MAV MOS...TAKING INTO CONSIDERATION THE MOSTLY CLOUDY SKIES THAT WILL ACCOMPANY A CLIPPER SYSTEM AS IT MOVES OFF TO THE EAST. WEDNESDAY NIGHTS CLIPPER WILL HAVE A BIT MORE MOISTURE WITH IT THAN THE ONES THAT HAVE TRAVERSED THE AREA OVER THE WEEKEND. HOWEVER...THIS SYSTEM STILL ISNT ALL THAT IMPRESSIVE AND IT WILL BE MOVING BY RATHER QUICKLY. MODEL CROSS SECTIONS SHOWING ABOUT A 12 HOUR PERIOD WITH GOOD MOISTURE. INITIALLY THROUGH THE DEPTH OF THE ATMOSPHERE...FROM 0Z THU UNTIL 8Z OR SO...WITH MUCH SHALLOWER BUT PERSISTENT LOW LEVEL MOISTURE IN PLACE AFTER 8Z. SHOULD NOT SEE MUCH MORE THAN SCATTERED LIGHT SNOW SHOWERS...ESPECIALLY CONSIDERING THE SPEED OF THE SYSTEM...THESE WILL GRADUALLY TAPER TO FLURRIES ASSOCIATED WITH THE CLOUDS TRAILING THE CLIPPER AS IT MOVES OFF TO THE NORTHEAST. MADE A FEW SLIGHT ADJUSTMENTS TO THE WINDS...GOING WITH A SLIGHT INCREASE IN SPEED AND VEERING TO THE WEST AS THE CLIPPER MOVES BY WEDNESDAY THURSDAY NIGHT. DEWPOINTS WERE IN GOOD SHAPE FOR THE MOST PART SO ONLY A FEW SLIGHT CHANGES WERE MADE THERE. MADE ADJUSTMENTS TO THE WEATHER AND QPF GRIDS TO ACCOUNT FOR CHANGES MADE TO POPS AND SKY COVER. FORECAST WILL BE OUT SHORTLY. EXTENDED...THURSDAY THROUGH MONDAY... ONLY A FEW MINOR CHANGES MADE IN THIS PORTION OF THE FORECAST. GFS AND ECMWF BOTH HANDLING LONG TERM SYNOPTIC PATTERNS PRETTY WELL. WITH SUPPORT FROM THE ECMWF...THE GFS SOLUTION LOOKED GOOD. YET ANOTHER CLIPPER SYSTEM WILL TRAVERSE THE REGION THURSDAY AFTERNOON INTO FRIDAY MORNING. BROKEN TO OVERCAST MIDDLE LEVEL CLOUD COVER AND A FEW SNOW SHOWERS WILL ACCOMPANY THIS FEATURE AS IT RACES OF TO THE EAST. THIS DISTURBANCE WILL GRADUALLY GIVE WAY TO CANADIAN HIGH PRESSURE FRIDAY...SATURDAY...AND MOST OF SUNDAY. ANOTHER UPPER LEVEL DISTURBANCE WILL MOVE BY THE AREA SUNDAY NIGHT INTO MONDAY. A CORRESPONDING INCREASE IN CLOUDINESS IS ANTICIPATED SUNDAY EVENING AS THIS FEATURE APPROACHES. DAYTIME HIGH TEMPERATURES SEEMED A BIT COOL...SO THESE WERE INCREASED SLIGHTLY BASED UPON SKY COVER FORECAST AND 12Z MEXMOS DATA. WITH PLENTY OF COLD DRY AIR IN PLACE...ANTICIPATE TEMPERATURES WILL WARM A BIT FASTER THAN PREVIOUSLY FORECAST DURING THE WEEKEND. WENT A BIT WARMER WITH SUNDAY HIGH TEMPS AS WELL...BUT STILL BELOW MOS NUMBERS DUE TO INCREASE IN CLOUD COVER ANTICIPATED. OVERNIGHT LOWS WERE INCREASED A BIT AS WELL FOR SATURDAY NIGHT AND SUNDAY...ACCOUNTING FOR INCREASED SOUTHERLY FLOW AND CLOUD COVER. REST OF FORECAST WAS IN GOOD SHAPE. && .PREV DISCUSSION... WINDS HAVE SHIFTED TO THE SW AND TEMPS HAVE WARMED TO THE POINT THAT THE FLURRIES HAVE ENDED. RADAR STILL SHOWING RETURNS FROM OUR ERN COUNTIES BUT CALLS CONFIRM THAT THIS IS A DISSIPATING...UPSLOPE CLOUD DECK AT ABOUT 2K. COLD START TO DAY AND PREVAILING CLOUDS THIS MORNING SHOULD KEEP TEMPS SOMEWHAT SUPPRESSED GIVEN LOW ANGLE OF SUN. 450 AM EST MON DEC 4 2006 A SHORT WAVE IS CURRENTLY PASSING ACROSS THE COMMONWEALTH AND IS STRONG ENOUGH TO GENERATE A BAND OF LOW CLOUDS AND FLURRIES ACROSS PORTIONS OF THE OHIO VALLEY THIS MORNING. MOST IF NOT ALL OF THIS ACTIVITY WILL HAVE PUSHED EAST OUT OF EASTERN KENTUCKY BY MID DAY. HENCE... HAVE INCLUDED FLURRIES IN THE FCST PACKAGE FOR THIS MORNING. OTHERWISE...NO MAJOR CHANGES TO THE FCST PACKAGE. THURSDAYS SHORTWAVE...AND CLIPPER SYSTEM HAS COME IN A BIT STRONGER WITH THE 0Z RUN. FCST SOUNDINGS AND TIME HEIGHT SECTIONS ARE SHOWING MORE MOISTURE AND A MORE FAVORABLE ENVIRONMENT FOR DENDRITIC GROWTH AS WELL. THEREFORE KEPT THE SLIGHT POP IN THE FORECAST FOR WEDNESDAY NIGHT AND EARLY THURSDAY. MADE SOME MINOR TWEAKS TO THE TEMPS FOR CCF PURPOSES. MOST SIGNIFICANT CHANGE WAS TO DROP TODAYS HIGH TEMPS A COUPLE OF DEGREES. WILL HAVE EXTRA CLOUD COVER TO DEAL WITH THROUGH THE MORNING AND COLD AIR ADVECTION THROUGH MOST OF THE DAY LIGHT HOURS. MODELS...MOS GUIDANCE DO HAVE WINDS SHIFTING QUICKLY TO THE SOUTHWEST LATE THIS AFTERNOON...INTO THE EVENING AHEAD OF THE NEXT WEAK CLIPPER SYSTEM. HOWEVER...THIS TAKES PLACE AFTER PEAK HEATING OF THE DAY. ALL THINGS CONSIDERED...FELT LOWER WAS THE WAY TO GO. 1059 PM EST SUN DEC 3 2006 SHORT TERM...REST OF TONIGHT... RADAR TRENDS IN INDIANA AND SOUTHWEST OHIO SHOW SOME FLURRIES ALONG THE H5 TROUGH AXIS/VORT MAX MOVING THROUGH. MODELS SHOW A LITTLE LESS MOISTURE AT 925 AND 900 MB IN OUR CWA WHICH WOULD INDICATE A LITTLE LESS CHANCE FOR FLURRIES...BUT I BELIEVE THERE COULD BE A FEW SNOWFLAKES WITH THE SC LAYER MOVING IN. ISSUED ANOTHER UPDATE TO ADD THESE TO THE FORECAST. KEPT THE FLURRIES OUT OF THE SOUTHERN COUNTIES OF THE CWA. SATELLITE ALSO SHOWS THE SC LAYER BECOMING MORE DEVELOPED TO OUR NORTHWEST. UPDATED TEXT FORECAST IS ALREADY ISSUED. 915 PM EST SUN DEC 3 2006 SHORT TERM...THE REST OF TONIGHT... AREA OF CI WITH SOME AC CONTINUES TO MOVE ACROSS THE AREA. ANOTHER NARROW BAND OF LOWER AC WAS MOVING IN FROM THE NORTHWEST AHEAD OF AN H5 TROUGH. THIS TROUGH WILL SWING THROUGH EASTERN KENTUCKY BETWEEN 6Z AND 10Z OVERNIGHT. LOOKING AT SATELLITE PICTURES AND SURFACE OBS...AN AREA OF SC WAS MOVING SOUTHEAST THROUGH INDIANA. THERE WERE EVEN A FEW FLURRIES REPORTED IN THE SURFACE OB...AND DEPICTED ON WEATHER SERVICE RADAR...NEAR IND. THE GFS IS SHOWING LOWER RH IN THE LOWER LEVELS AS COMPARED TO THE RUC AND THE WRF. ATTM...I BELIEVE THE HIGHER LOWER LEVEL RH/S SHOWN IN THE RUC AND WRF ARE MORE REASONABLE. HAVE DECIDED TO GO WITH PARTLY CLOUDY SKIES FOR THE ENTIRE NIGHT FOR EASTERN KENTUCKY. SOME OF THE SC OVER INDIANA SHOULD WORK ITS WAY INTO OUR CWA. THESE CLOUDS SHOULD BE MAINLY SCATTERED IN NATURE MOST OF THE NIGHT. ALSO OPENED UP A TEMPERATURE RANGE IN SOME AREAS OVERNIGHT. SHOULD BE A COLD NIGHT WITH LOWS 15 TO 20 WITH GOOD CAA AT 850 MB. 850 MB TEMPS SHOULD BE DROPPING FROM CURRENT VALUES OF AROUND -3 DEG C...TO AROUND -12 DEG C BY 7 AM MONDAY MORNING. UPDATED FORECAST PRODUCTS WILL BE OUT SOON. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AR ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1103 AM EST MON DEC 4 2006 .DISCUSSION... WINDS HAVE SHIFTED TO THE SW AND TEMPS HAVE WARMED TO THE POINT THAT THE FLURRIES HAVE ENDED. RADAR STILL SHOWING RETURNS FROM OUR ERN COUNTIES BUT CALLS CONFIRM THAT THIS IS A DISSIPATING...UPSLOPE CLOUD DECK AT ABOUT 2K. COLD START TO DAY AND PREVAILING CLOUDS THIS MORNING SHOULD KEEP TEMPS SOMEWHAT SUPPRESSED GIVEN LOW ANGLE OF SUN. && .PREV DISCUSSION... 450 AM EST MON DEC 4 2006 A SHORT WAVE IS CURRENTLY PASSING ACROSS THE COMMONWEALTH AND IS STRONG ENOUGH TO GENERATE A BAND OF LOW CLOUDS AND FLURRIES ACROSS PORTIONS OF THE OHIO VALLEY THIS MORNING. MOST IF NOT ALL OF THIS ACTIVITY WILL HAVE PUSHED EAST OUT OF EASTERN KENTUCKY BY MID DAY. HENCE... HAVE INCLUDED FLURRIES IN THE FCST PACKAGE FOR THIS MORNING. OTHERWISE...NO MAJOR CHANGES TO THE FCST PACKAGE. THURSDAYS SHORTWAVE...AND CLIPPER SYSTEM HAS COME IN A BIT STRONGER WITH THE 0Z RUN. FCST SOUNDINGS AND TIME HEIGHT SECTIONS ARE SHOWING MORE MOISTURE AND A MORE FAVORABLE ENVIRONMENT FOR DENDRITIC GROWTH AS WELL. THEREFORE KEPT THE SLIGHT POP IN THE FORECAST FOR WEDNESDAY NIGHT AND EARLY THURSDAY. MADE SOME MINOR TWEAKS TO THE TEMPS FOR CCF PURPOSES. MOST SIGNIFICANT CHANGE WAS TO DROP TODAYS HIGH TEMPS A COUPLE OF DEGREES. WILL HAVE EXTRA CLOUD COVER TO DEAL WITH THROUGH THE MORNING AND COLD AIR ADVECTION THROUGH MOST OF THE DAY LIGHT HOURS. MODELS...MOS GUIDANCE DO HAVE WINDS SHIFTING QUICKLY TO THE SOUTHWEST LATE THIS AFTERNOON...INTO THE EVENING AHEAD OF THE NEXT WEAK CLIPPER SYSTEM. HOWEVER...THIS TAKES PLACE AFTER PEAK HEATING OF THE DAY. ALL THINGS CONSIDERED...FELT LOWER WAS THE WAY TO GO. 1059 PM EST SUN DEC 3 2006 SHORT TERM...REST OF TONIGHT... RADAR TRENDS IN INDIANA AND SOUTHWEST OHIO SHOW SOME FLURRIES ALONG THE H5 TROUGH AXIS/VORT MAX MOVING THROUGH. MODELS SHOW A LITTLE LESS MOISTURE AT 925 AND 900 MB IN OUR CWA WHICH WOULD INDICATE A LITTLE LESS CHANCE FOR FLURRIES...BUT I BELIEVE THERE COULD BE A FEW SNOWFLAKES WITH THE SC LAYER MOVING IN. ISSUED ANOTHER UPDATE TO ADD THESE TO THE FORECAST. KEPT THE FLURRIES OUT OF THE SOUTHERN COUNTIES OF THE CWA. SATELLITE ALSO SHOWS THE SC LAYER BECOMING MORE DEVELOPED TO OUR NORTHWEST. UPDATED TEXT FORECAST IS ALREADY ISSUED. 915 PM EST SUN DEC 3 2006 SHORT TERM...THE REST OF TONIGHT... AREA OF CI WITH SOME AC CONTINUES TO MOVE ACROSS THE AREA. ANOTHER NARROW BAND OF LOWER AC WAS MOVING IN FROM THE NORTHWEST AHEAD OF AN H5 TROUGH. THIS TROUGH WILL SWING THROUGH EASTERN KENTUCKY BETWEEN 6Z AND 10Z OVERNIGHT. LOOKING AT SATELLITE PICTURES AND SURFACE OBS...AN AREA OF SC WAS MOVING SOUTHEAST THROUGH INDIANA. THERE WERE EVEN A FEW FLURRIES REPORTED IN THE SURFACE OB...AND DEPICTED ON WEATHER SERVICE RADAR...NEAR IND. THE GFS IS SHOWING LOWER RH IN THE LOWER LEVELS AS COMPARED TO THE RUC AND THE WRF. ATTM...I BELIEVE THE HIGHER LOWER LEVEL RH/S SHOWN IN THE RUC AND WRF ARE MORE REASONABLE. HAVE DECIDED TO GO WITH PARTLY CLOUDY SKIES FOR THE ENTIRE NIGHT FOR EASTERN KENTUCKY. SOME OF THE SC OVER INDIANA SHOULD WORK ITS WAY INTO OUR CWA. THESE CLOUDS SHOULD BE MAINLY SCATTERED IN NATURE MOST OF THE NIGHT. ALSO OPENED UP A TEMPERATURE RANGE IN SOME AREAS OVERNIGHT. SHOULD BE A COLD NIGHT WITH LOWS 15 TO 20 WITH GOOD CAA AT 850 MB. 850 MB TEMPS SHOULD BE DROPPING FROM CURRENT VALUES OF AROUND -3 DEG C...TO AROUND -12 DEG C BY 7 AM MONDAY MORNING. UPDATED FORECAST PRODUCTS WILL BE OUT SOON. 632 PM EST SUN DEC 3 2006 AVIATION...8PM TONIGHT-8PM MONDAY EVENING... H5 TROUGH WILL BE MOVING ACROSS THE AREA THIS EVENING. PLENTY OF CI SHOWN ON SATELLITE AND OBSERVATIONS ACROSS THE REGION. A BAND OF AC WILL BE MOVING IN FROM THE WEST THROUGH THE EVENING. WE SHOULD BE ON THE SOUTHERN FRINGE OF THE AC. WENT WITH SCT100 BKN230 IN THE TAFS TO COVER THE ABOVE CONDITIONS. MODELS...ESPECIALLY THE WRF AND THE RUC...ARE HINTING AT SOME SC MOVING IN BEHIND THE TROUGH. LATEST SATELLITE AND SURFACE OBS DO SHOW SOME SC FORMING OVER INDIANA. PUT SCT028 IN ALL THE TAF SITES FOR THIS FEATURE. THE SC SHOULD HANG ON LONGEST AT JKL...BUT ATTM COVERAGE SHOULD ONLY BE SCT. MORE SCT CI SHOULD MOVE OVER THE AREA MONDAY AFTERNOON. 213 PM EST SUN DEC 3 2006 WITH HIGH PRESSURE STILL IN CONTROL...THIS FCST IS MAINLY FOR TEMPS. TONIGHT SHOULD BE THE COLDEST OF THE WEEK AND WITH CONTINUED ADVECTION OF SINGLE DIGIT DWPTS...THIN CI...AND LIGHT WINDS...SEE NO REASON WHY MIN TEMPS SHOULD NOT GO A TAD LOWER THAN THE UPPER TEENS WE SAW LAST NIGHT. NORTH WINDS ON MON SHOULD KEEP HIGHS DOWN BUT STILL THINK WE WILL BREAK THE FREEZING MARK AND MAY EVEN SEE A COUPLE OF SITES NEAR 40. A TAD MORE CLOUD COVER MON NIGHT WILL HELP KEEP MINS TO ONLY THE LOWER 20S AND THEN A RETURN TO A MORE SWRLY FLOW WILL HELP TUE WARM INTO THE LOWER TO MID 40S. WEAK S/WV TO TRANSGRESS THE GT LKS WED NITE INTO THU BUT WITH SO LITTLE MOISTURE AND S/WV ENERGY WILL ONLY FCST LOW SLGHT CHC POP. QPF SHOULD BE NEARLY NON-EXISTENT...WITH BEST CHC IN THE SERN MTNS WITH UPSLOPE AS THE SYSTEM DEPARTS. COULD EVEN BE A FLURRY OR TWO FROM THIS SYSTEM BUT AM NOT EXPECTING ENUF TO MEASURE OTHER THAN THE TOPS OF PINE AND BLACK MTNS. WITH THE DEPARTING S/WV AND CAA THU NITE...AM EXPECTING ANOTHER COLD NIGHT AND WILL FCST BELOW MOS. OTHERWISE... NEXT 7 DAYS SHOULD BE DRY WITH TEMPS SLIGHTLY BELOW SEASONAL AVERAGES. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DUSTY ky AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TAUNTON MA 1027 AM EST MON DEC 4 2006 .SHORT TERM /REST OF TODAY/... SNOW IS DEPARTING THE FORECAST AREA LATE THIS MORNING. RADAR IS CURRENTLY DETECTING LIGHTER SNOW SHOWERS AND FLURRIES FORMING WITH LEFTOVER MOISTURE AND DEVELOPING COLD AIR ADVECTION PATTERN. SKIES EXPECTED TO BECOME MOSTLY SUNNY THIS AFTERNOON AS COLD AIR ADVECTION EASES EXCEPT PARTLY SUNNY ACROSS THE EAST SLOPES OF THE BERKS. TEMPERATURE FORECAST LOOKS ON TARGET. CLEANED UP WORDING ON THE LATEST ZFP TO INCORPORATE TRENDS. MARINE: GALES REMAIN IN EFFECT ACROSS THE OUTER WATERS AS WELL AS CAPE COD BAY AND NANTUCKET SOUND...WITH A SMALL CRAFT ADVISORY ELSEWHERE. AVIATION: IFR CEILINGS WILL INCREASE TO VFR BY 16Z. A PUBLIC INFORMATION STATEMENT WILL BE SENT SHORTLY WITH LATEST SNOWFALL TOTALS...WITH THE FIRST MEASURABLE SNOW OF THE SEASON AT MANY LOCATIONS. .PREVIOUS DISCUSSION... /ISSUED 615 AM EST MON DEC 4 2006/ ..RAIN CHANGING TO A BRIEF PERIOD OF WET SNOW ACROSS EASTERN MA AND RHODE ISLAND EARLY THIS MORNING MAY LEAVE A SMALL SLUSHY ACCUMULATION BUT ROADWAYS WILL REMAIN WET... MESOSCALE UPDATE... CURRENT FORECAST IS IN GOOD SHAPE AND NO BIG CHANGES PLANNED. RAIN IS QUICKLY CHANGING TO WET SNOW ACROSS EASTERN MA AND RHODE ISLAND. SURFACE WINDS HAVE SHIFTED TO THE NORTHWEST AT 10 TO 15 MPH ACROSS THE REGION. THIS IS ALLOWING SURFACE DEWPOINTS IN THE UPPER 20S TO NEAR 30 TO ADVECT INTO THE REGION. THIS IS RESULTING IN TEMPERATURES BEGINNING TO WET BULB ALLOWING RAIN TO QUICKLY CHANGE TO WET SNOW FROM NORTHWEST TO SOUTHEAST. THE MAIN THING IS THAT THIS SNOW IS NOT EXPECTED TO HAVE AN IMPACT ON THE MAIN ROADWAYS SINCE TEMPERATURES SHOULD REMAIN JUST ABOVE FREEZING. A SMALL SLUSHY ACCUMULATION IS POSSIBLE ON CAR TOPS AND AND GRASSY SURFACES...PARTICULARLY IN THE HILLS OF NORTHWEST RHODE ISLAND AS WELL AS WESTERN NORFOLK AND WESTERN NORFOLK COUNTY. OTHERWISE...DRIER AIR RAPIDLY MOVING IN FROM THE WEST WILL CAUSE ALL THE PRECIPITATION TO EXIT THE REGION BY MID TO LATE MORNING. WILL GO AHEAD AND REFRESH THE SPECIAL WEATHER STATEMENT. ALL IN ALL...A TASTE OF WINTER EARLY THIS MORNING BUT WITH NO ACCUMULATIONS EXPECTED ON THE MAIN ROADWAYS. FRANK PREVIOUS DISCUSSION FROM 354 AM... SHORT TERM /REST OF TODAY/... JUST A QUICK UPDATE TO DESCRIBE WHAT IS HAPPENING RIGHT NOW... FORECAST REMAINS VALID. COASTAL FRONT HAS SET UP ALONG S COAST AND STEADIEST RAINS ARE FALLING IN MILDER AIR OVER CAPE COD AND ISLANDS...BUT HAS EDGED ONTO MUCH OF S COAST AND WAS AS FAR INLAND AS KPYM. THIS IS A WELL DEFINED BAND OF PRECIPITATION THAT EXTENDS ALL WAY BACK TO MID ATLANTIC COAST...AND IS EXPECTED TO BEGIN A PIVOT BACK TO I-95 /PVD TO BOS/ IN NEXT 3 HOURS AS SURFACE LOW EMERGES FROM OFF NC COAST. 06Z NAM SUGGESTS 12Z-15Z AS TO MAIN TIMEFRAME FOR THIS EVENT IN SOUTHERN NEW ENGLAND. AT SAME TIME...YOU CAN SEE ANOTHER AREA OF RETURNS COMING UP FROM NYC INTO CT...ALL OF WHICH IS BASED AT MID LEVELS AND NOT REACHING GROUND PER SURFACE OBSERVATIONS. THIS IS ASSOCIATED WITH SMALL PACKET OF MID LEVEL FRONTOGENESIS WHICH WAS FORECAST BY PAST SEVERAL RUNS OF NAM/GFS...BUT PROBLEM IS WE HAVE A PRONOUNCED DRY LAYER BETWEEN 950 AND 750 MB WHICH IS PREVENTING ANYTHING FROM REACHING GROUND. SO UNLESS WE ARE ABLE TO OVERCOME THIS DRY LAYER IN NEXT 3 HOURS...WE MAY NOT SEE ANY PRECIPITATION NW OF I-95 THIS MORNING. PREVIOUS DISCUSSION... /ISSUED 322 AM EST MON DEC 4 2006/ .STILL LOOKING AT MINOR ACCUMULATIONS OF AN INCH OR TWO THIS MORNING IN RI AND INTERIOR E MA... SHORT TERM /TODAY THROUGH TUESDAY/... EVEN THOUGH MODELS ARE IN GOOD AGREEMENT WITH RESPECT TO TRACK OF SURFACE LOW OUTSIDE 40/70 BENCHMARK...THERE ARE SOME DIFFERENCES WITH RESPECT TO HOW FAR INLAND PRECIPITATION WILL GET THIS MORNING. 00Z NAM IS MUCH DRIER THAN 00Z GFS...CANADIAN AND RUC. BASED UPON RADAR TRENDS WE ARE MORE INCLINED TO FOLLOW GFS CAMP WHICH BRINGS AROUND 0.10 INCH INTO KSFZ-KBOS...0.25 INCH KPVD-KTAN AND 0.50-0.75 INCH ONTO CAPE COD AND ISLANDS. PRECIPITATION SHIELD IS BLOSSOMING ONTO CAPE COD AND ISLANDS AT THIS TIME AND WE EXPECT IT TO BEGIN A GRADUAL WESTWARD SHIFT AS WE HEAD TOWARD DAYBREAK. CROSS SECTIONS AND TEMPERATURE PROFILES SHOW ALL RAIN FROM ISLANDS ONTO S COAST WHERE TEMPERATURES HAVE WARMED WELL INTO 40S...BUT IT IS A DIFFERENT STORY IN RI AND ESPECIALLY INTERIOR SE MA WHERE READINGS HAVE NOT YET BEGUN TO RECOVER FROM LAST NIGHTS RADIATIONAL COOLING. IN FACT WINDS HAVE GONE LIGHT AND VARIABLE WHICH HAS ALLOWED COLDER AIR TO REMAIN LOCKED IN. MAIN QUESTION TO BE ANSWERED IN NEXT FEW HOURS IS...DOES THIS COLDER AIR GET SCOURED OUT? WE THINK IT WILL SINCE COLD LAYER IS FAIRLY SHALLOW...AND ONCE GRADIENT FORCES SW WINDS TO PICK UP...MILDER AIR SHOULD WIN OUT. THAT SAID...WE DO EXPECT TO SEE A RAIN/SNOW MIX ALONG KPVD/KBOS CORRIDOR BUT IT IS POSSIBLE SOME PLACES WILL SEE ALL SNOW AT START. FOLLOWING 00Z GFS WE THINK PRECIPITATION WILL GET AS FAR INLAND AS NE CT... NW RI AND EASTERN MA...ROUGHLY FROM KIJD-KBED-KLWM. THAT CERTAINLY SEEMS TO BE TREND SETTING UP ON RADAR AS WELL...IF ANYTHING WE ARE BEING A BIT GENEROUS! HEIGHT OF THIS EVENT WILL OCCUR RIGHT AROUND 7 AM...WHEN MODELS SHOW BEST UPWARD MOTION MOVING OVER SE NEW ENGLAND FROM MID LEVEL DEFORMATION ZONE COUPLED WITH BAND OF STRONG LOW AND MID LEVEL FRONTOGENESIS. 03Z RUC DEPICTS THIS NICELY AS WELL. AT SAME TIME LOWER LEVELS WILL COOL OFF AS WINDS SHIFT TO N...IN RESPONSE TO SYSTEM PASSING SE OF REGION. 925MB TEMPERATURES SUGGEST A CHANGE TO SNOW AS FAR SE AS KPVD-KTAN-KPYM...AND THAT IS CORRIDOR WHERE BURST OF SNOW IS FAVORED. THIS WILL BE A SHORT LIVED EVENT AND ACCUMULATIONS OF AN INCH OR TWO STILL SEEM MOST LIKELY FROM NORTHERN RI INTO INTERIOR SE MA...WITH ABOUT AN INCH KIJD-KLWM...AND LITTLE ACCUMULATION ALONG BOTH E MA COAST AND S COAST. THIS DOES NOT WARRANT ADVISORIES DESPITE BEING FIRST EXPECTED SNOWFALL OF SEASON...BUT SINCE IT WILL COINCIDE WITH MORNING COMMUTE WE WILL UPDATE SPECIAL WEATHER STATEMENT. WE THINK MOST OF ACCUMULATION WILL OCCUR ON GRASS WITH HIGHWAYS AND MAIN ROADS STAYING WET...THOUGH CERTAINLY IF IT COMES DOWN HARD ENOUGH FOR A SHORT TIME WE COULD HAVE A LAYER OF SLUSH FORM. ONCE SYSTEM DEPARTS MID TO LATE MORNING...RAPID CLEARING WILL TAKE PLACE FROM W TO E AND NW WINDS WILL BECOME GUSTY. NOT MUCH EXPECTED TONIGHT INTO TUE OTHER THAN SOME MID AND HIGH CLOUDS. MODELS BRING A WEAK FRONT THROUGH REGION TUE BUT MOISTURE APPEARS LIMITED SO NO MENTION OF FLURRIES. LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... WITH MOSTLY CLEAR SKIES AND LIGHT WIND TUESDAY NIGHT...EXPECT A GOOD RADIATIONAL COOLING ACROSS THE REGION. LOWS SHOULD RANGE FROM THE MID TEENS TO LOWER 20S ACROSS MOST LOCATIONS...WITH UPPER 20S EXPECTED IN THE URBAN HEAT ISLAND OF BOSTON. LOW PRESSURE DEVELOPING OVER THE GREAT LAKES ON WEDNESDAY WILL RESULT IN SOUTHWEST FLOW AND MILDER TEMPERATURES. HIGHS SHOULD MAINLY BE IN THE 40S AND IT SHOULD BE COME BREEZY WITH GUSTS TO 35 MPH EXPECTED AS THE LOW LEVEL JET INCREASES. THE NAM BUFKIT IS A BIT STRONGER THAN THE OTHER MODELS AND SUGGESTS THAT WE COULD BE DEALING WITH MARGINAL WIND ADVISORY CRITERIA AT SOME LOCATIONS. ALTHOUGH THINGS COULD CHANGE...RIGHT NOW THIS IS JUST A LOW PROBABILITY AS WE FEEL THE NAM IS A BIT OVERDONE. HOWEVER...FEEL WE STILL MAY HIT WIND ADVISORY THRESHOLDS IN THE BLUE HILLS BECAUSE OF ITS ADDED ELEVATION. WARM AIR ADVECTION WEDNESDAY NIGHT SHOULD KEEP THE ATMOSPHERE FROM DECOUPLING. NOT A LOT OF LOW LEVEL MOISTURE AVAILABLE AHEAD OF THE COLD FRONT...SO WILL JUST GO WITH A SLIGHT CHANCE POP. WARM AIR ADVECTION MAY ALLOW FOR AN ISOLATED RAIN OR SNOW SHOWER TO POP UP BUT NOT MUCH MORE THAN THAT. LOW TEMPERATURES SHOULD REMAIN ABOVE FREEZING ALONG THE COAST WITH SOUTHWEST WINDS AHEAD OF THE FRONT. COLD FRONT LOOKS TO MOVE THROUGH THE REGION ON THURSDAY. NAM SEEMS WAY TO FAST WITH THE FRONT COMPARED TO THE GFS/ECMWF. THEREFORE...EXPECT MUCH OF THE REGION TO RECOVER WELL INTO THE 40S. NOT MUCH MOISTURE AVAILABLE WITH THE APPROACHING COLD FRONT. WILL GO WITH A SLIGHT CHANCE POP FOR AN ISOLATED RAIN OR SNOW SHOWER. MUCH COLDER AIR WILL MOVE IN BEHIND THE FRONT THURSDAY NIGHT. LOWS SHOULD FALL INTO THE TEENS ACROSS THE INTERIOR...WITH 20S ALONG THE COASTAL PLAIN. HIGHS ON FRIDAY SHOULD BE JUST IN THE 30S AND PORTIONS OF THE HIGHER TERRAIN MAY SEE HIGHS ONLY IN THE UPPER 20S. MOST OF THE MODELS AGREE ON A SECONDARY STORM DEVELOPING ALONG THE DEPARTING COLD FRONT THURSDAY NIGHT AND FRIDAY. HOWEVER...THE CANADIAN/GFS/ECMWF AND THE GFS ENSEMBLES HAVE THIS OCCURRING WELL EAST OF OUR REGION. THEREFORE...WE ARE EXPECTING FRIDAY AND SATURDAY TO BE DRY. HOWEVER...THE UKMET IS A BIT CLOSER AND INDICATES WE MIGHT BE BRUSHED BY THE STORM. THE UKMET HAS SHOWN THIS FOR SEVERAL RUNS IN A ROW...BUT THIS LATEST 00Z RUN HAS TRENDED FURTHER EAST AND MORE PROGRESSIVE. THINGS CAN CHANGE THIS FAR OUT...BUT THE MOSTLY LIKELY SCENARIO IS THAT WE WILL BE DRY AND NOT IMPACTED BY THE COASTAL STORM LATE IN THE WEEK. OTHERWISE...LOOKS LIKE TEMPERATURES WILL BEGIN TO MODERATE EARLY NEXT WEEK AS THE NORTHEAST TROUGH IS REPLACED BY ZONAL FLOW. HIGH TEMPERATURES SHOULD RECOVER WELL INTO THE 40S ON SUNDAY. AVIATION... CONDITIONS WILL LOWER TO MVFR AS FAR INLAND AS KPVD AND KBOS TERMINAL AREAS...WITH A PERIOD OF IFR CONDITIONS PROBABLE NEAR S COAST THIS MORNING. PRECIPITATION TYPE WILL BE ALL RAIN FROM ISLANDS ONTO S COAST...AND INITIALLY A RAIN/SNOW MIX FOR KBOS/KPVD WHICH WILL CHANGE TO ALL SNOW AROUND 12Z. HEIGHT OF THIS EVENT WILL BE IN 11Z- 15Z TIMEFRAME FOR COASTAL TERMINALS. IT WILL REMAIN VFR FARTHER INLAND WHERE CEILINGS SHOULD ONLY LOWER TO 4KFT THIS MORNING. RAPID CLEARING WILL TAKE PLACE BEHIND SYSTEM STARTING IN CT VALLEY 14-15Z AND ON COASTAL PLAIN 16-17Z. NW WINDS WILL GUST TO 25-30KT FROM LATER THIS MORNING INTO EARLY THIS EVENING AS LOW DEEPENS OFFSHORE. MARINE... GALE WARNINGS REMAIN POSTED FOR NANTUCKET SOUND AND FOR OUTER WATERS... WHERE NW WINDS WILL RAPIDLY INCREASE AROUND MID MORNING AS LOW PASSES E OF NEW ENGLAND AND DEEPENS. ELSEWHERE WE HAVE SMALL CRAFT ADVISORIES ISSUED FOR 25 TO 30KT GUSTS. WINDS WILL CONTINUE TO GUST TO AROUND 25 KT THROUGH TONIGHT...THOUGH THEY WILL SUBSIDE LATE TONIGHT NEAR COAST. WINDS AND SEAS WILL DIMINISH TUE. LOW LEVEL JET OF 45 TO 55 KNOTS WILL DEVELOP WEDNESDAY AFTERNOON AND EVENING. EVEN THOUGH ITS WARM ADVECTION ON SOUTHWEST WINDS...THE AIR WILL BE COLDER THAN OUR CURRENT OCEAN WATER TEMPERATURES. THEREFORE...WE EXPECT STRONG SCA OR MARGINAL GALE FORCE WIND GUSTS WEDNESDAY AFTERNOON AND NIGHT. STRONG SCA WILL ALSO PROBABLY NEEDED THURSDAY AND FRIDAY...WITH COLD ADVECTION BEHIND THE COLD FRONT. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...GALE WARNING FOR ANZ231-232-250-254-255 UNTIL 7 PM MONDAY. ...SMALL CRAFT ADVISORY FOR ANZ230-233>237 UNTIL 6 AM TUESDAY. && $$ SHORT TERM...STRAUSS/KAB ma AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TAUNTON MA 615 AM EST MON DEC 4 2006 ...RAIN CHANGING TO A BRIEF PERIOD OF WET SNOW ACROSS EASTERN MA AND RHODE ISLAND EARLY THIS MORNING MAY LEAVE A SMALL SLUSHY ACCUMULATION BUT ROADWAYS WILL REMAIN WET... .MESOSCALE UPDATE... CURRENT FORECAST IS IN GOOD SHAPE AND NO BIG CHANGES PLANNED. RAIN IS QUICKLY CHANGING TO WET SNOW ACROSS EASTERN MA AND RHODE ISLAND. SURFACE WINDS HAVE SHIFTED TO THE NORTHWEST AT 10 TO 15 MPH ACROSS THE REGION. THIS IS ALLOWING SURFACE DEWPOINTS IN THE UPPER 20S TO NEAR 30 TO ADVECT INTO THE REGION. THIS IS RESULTING IN TEMPERATURES BEGINNING TO WET BULB ALLOWING RAIN TO QUICKLY CHANGE TO WET SNOW FROM NORTHWEST TO SOUTHEAST. THE MAIN THING IS THAT THIS SNOW IS NOT EXPECTED TO HAVE AN IMPACT ON THE MAIN ROADWAYS SINCE TEMPERATURES SHOULD REMAIN JUST ABOVE FREEZING. A SMALL SLUSHY ACCUMULATION IS POSSIBLE ON CAR TOPS AND AND GRASSY SURFACES...PARTICULARLY IN THE HILLS OF NORTHWEST RHODE ISLAND AS WELL AS WESTERN NORFOLK AND WESTERN NORFOLK COUNTY. OTHERWISE...DRIER AIR RAPIDLY MOVING IN FROM THE WEST WILL CAUSE ALL THE PRECIPITATION TO EXIT THE REGION BY MID TO LATE MORNING. WILL GO AHEAD AND REFRESH THE SPECIAL WEATHER STATEMENT. ALL IN ALL...A TASTE OF WINTER EARLY THIS MORNING BUT WITH NO ACCUMULATIONS EXPECTED ON THE MAIN ROADWAYS. FRANK && .PREVIOUS DISCUSSION FROM 354 AM... .SHORT TERM /REST OF TODAY/... JUST A QUICK UPDATE TO DESCRIBE WHAT IS HAPPENING RIGHT NOW... FORECAST REMAINS VALID. COASTAL FRONT HAS SET UP ALONG S COAST AND STEADIEST RAINS ARE FALLING IN MILDER AIR OVER CAPE COD AND ISLANDS...BUT HAS EDGED ONTO MUCH OF S COAST AND WAS AS FAR INLAND AS KPYM. THIS IS A WELL DEFINED BAND OF PRECIPITATION THAT EXTENDS ALL WAY BACK TO MID ATLANTIC COAST...AND IS EXPECTED TO BEGIN A PIVOT BACK TO I-95 /PVD TO BOS/ IN NEXT 3 HOURS AS SURFACE LOW EMERGES FROM OFF NC COAST. 06Z NAM SUGGESTS 12Z-15Z AS TO MAIN TIMEFRAME FOR THIS EVENT IN SOUTHERN NEW ENGLAND. AT SAME TIME...YOU CAN SEE ANOTHER AREA OF RETURNS COMING UP FROM NYC INTO CT...ALL OF WHICH IS BASED AT MID LEVELS AND NOT REACHING GROUND PER SURFACE OBSERVATIONS. THIS IS ASSOCIATED WITH SMALL PACKET OF MID LEVEL FRONTOGENESIS WHICH WAS FORECAST BY PAST SEVERAL RUNS OF NAM/GFS...BUT PROBLEM IS WE HAVE A PRONOUNCED DRY LAYER BETWEEN 950 AND 750 MB WHICH IS PREVENTING ANYTHING FROM REACHING GROUND. SO UNLESS WE ARE ABLE TO OVERCOME THIS DRY LAYER IN NEXT 3 HOURS...WE MAY NOT SEE ANY PRECIPITATION NW OF I-95 THIS MORNING. && .PREVIOUS DISCUSSION... /ISSUED 322 AM EST MON DEC 4 2006/ ..STILL LOOKING AT MINOR ACCUMULATIONS OF AN INCH OR TWO THIS MORNING IN RI AND INTERIOR E MA... SHORT TERM /TODAY THROUGH TUESDAY/... EVEN THOUGH MODELS ARE IN GOOD AGREEMENT WITH RESPECT TO TRACK OF SURFACE LOW OUTSIDE 40/70 BENCHMARK...THERE ARE SOME DIFFERENCES WITH RESPECT TO HOW FAR INLAND PRECIPITATION WILL GET THIS MORNING. 00Z NAM IS MUCH DRIER THAN 00Z GFS...CANADIAN AND RUC. BASED UPON RADAR TRENDS WE ARE MORE INCLINED TO FOLLOW GFS CAMP WHICH BRINGS AROUND 0.10 INCH INTO KSFZ-KBOS...0.25 INCH KPVD-KTAN AND 0.50-0.75 INCH ONTO CAPE COD AND ISLANDS. PRECIPITATION SHIELD IS BLOSSOMING ONTO CAPE COD AND ISLANDS AT THIS TIME AND WE EXPECT IT TO BEGIN A GRADUAL WESTWARD SHIFT AS WE HEAD TOWARD DAYBREAK. CROSS SECTIONS AND TEMPERATURE PROFILES SHOW ALL RAIN FROM ISLANDS ONTO S COAST WHERE TEMPERATURES HAVE WARMED WELL INTO 40S...BUT IT IS A DIFFERENT STORY IN RI AND ESPECIALLY INTERIOR SE MA WHERE READINGS HAVE NOT YET BEGUN TO RECOVER FROM LAST NIGHTS RADIATIONAL COOLING. IN FACT WINDS HAVE GONE LIGHT AND VARIABLE WHICH HAS ALLOWED COLDER AIR TO REMAIN LOCKED IN. MAIN QUESTION TO BE ANSWERED IN NEXT FEW HOURS IS...DOES THIS COLDER AIR GET SCOURED OUT? WE THINK IT WILL SINCE COLD LAYER IS FAIRLY SHALLOW...AND ONCE GRADIENT FORCES SW WINDS TO PICK UP...MILDER AIR SHOULD WIN OUT. THAT SAID...WE DO EXPECT TO SEE A RAIN/SNOW MIX ALONG KPVD/KBOS CORRIDOR BUT IT IS POSSIBLE SOME PLACES WILL SEE ALL SNOW AT START. FOLLOWING 00Z GFS WE THINK PRECIPITATION WILL GET AS FAR INLAND AS NE CT... NW RI AND EASTERN MA...ROUGHLY FROM KIJD-KBED-KLWM. THAT CERTAINLY SEEMS TO BE TREND SETTING UP ON RADAR AS WELL...IF ANYTHING WE ARE BEING A BIT GENEROUS! HEIGHT OF THIS EVENT WILL OCCUR RIGHT AROUND 7 AM...WHEN MODELS SHOW BEST UPWARD MOTION MOVING OVER SE NEW ENGLAND FROM MID LEVEL DEFORMATION ZONE COUPLED WITH BAND OF STRONG LOW AND MID LEVEL FRONTOGENESIS. 03Z RUC DEPICTS THIS NICELY AS WELL. AT SAME TIME LOWER LEVELS WILL COOL OFF AS WINDS SHIFT TO N...IN RESPONSE TO SYSTEM PASSING SE OF REGION. 925MB TEMPERATURES SUGGEST A CHANGE TO SNOW AS FAR SE AS KPVD-KTAN-KPYM...AND THAT IS CORRIDOR WHERE BURST OF SNOW IS FAVORED. THIS WILL BE A SHORT LIVED EVENT AND ACCUMULATIONS OF AN INCH OR TWO STILL SEEM MOST LIKELY FROM NORTHERN RI INTO INTERIOR SE MA...WITH ABOUT AN INCH KIJD-KLWM...AND LITTLE ACCUMULATION ALONG BOTH E MA COAST AND S COAST. THIS DOES NOT WARRANT ADVISORIES DESPITE BEING FIRST EXPECTED SNOWFALL OF SEASON...BUT SINCE IT WILL COINCIDE WITH MORNING COMMUTE WE WILL UPDATE SPECIAL WEATHER STATEMENT. WE THINK MOST OF ACCUMULATION WILL OCCUR ON GRASS WITH HIGHWAYS AND MAIN ROADS STAYING WET...THOUGH CERTAINLY IF IT COMES DOWN HARD ENOUGH FOR A SHORT TIME WE COULD HAVE A LAYER OF SLUSH FORM. ONCE SYSTEM DEPARTS MID TO LATE MORNING...RAPID CLEARING WILL TAKE PLACE FROM W TO E AND NW WINDS WILL BECOME GUSTY. NOT MUCH EXPECTED TONIGHT INTO TUE OTHER THAN SOME MID AND HIGH CLOUDS. MODELS BRING A WEAK FRONT THROUGH REGION TUE BUT MOISTURE APPEARS LIMITED SO NO MENTION OF FLURRIES. LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... WITH MOSTLY CLEAR SKIES AND LIGHT WIND TUESDAY NIGHT...EXPECT A GOOD RADIATIONAL COOLING ACROSS THE REGION. LOWS SHOULD RANGE FROM THE MID TEENS TO LOWER 20S ACROSS MOST LOCATIONS...WITH UPPER 20S EXPECTED IN THE URBAN HEAT ISLAND OF BOSTON. LOW PRESSURE DEVELOPING OVER THE GREAT LAKES ON WEDNESDAY WILL RESULT IN SOUTHWEST FLOW AND MILDER TEMPERATURES. HIGHS SHOULD MAINLY BE IN THE 40S AND IT SHOULD BE COME BREEZY WITH GUSTS TO 35 MPH EXPECTED AS THE LOW LEVEL JET INCREASES. THE NAM BUFKIT IS A BIT STRONGER THAN THE OTHER MODELS AND SUGGESTS THAT WE COULD BE DEALING WITH MARGINAL WIND ADVISORY CRITERIA AT SOME LOCATIONS. ALTHOUGH THINGS COULD CHANGE...RIGHT NOW THIS IS JUST A LOW PROBABILITY AS WE FEEL THE NAM IS A BIT OVERDONE. HOWEVER...FEEL WE STILL MAY HIT WIND ADVISORY THRESHOLDS IN THE BLUE HILLS BECAUSE OF ITS ADDED ELEVATION. WARM AIR ADVECTION WEDNESDAY NIGHT SHOULD KEEP THE ATMOSPHERE FROM DECOUPLING. NOT A LOT OF LOW LEVEL MOISTURE AVAILABLE AHEAD OF THE COLD FRONT...SO WILL JUST GO WITH A SLIGHT CHANCE POP. WARM AIR ADVECTION MAY ALLOW FOR AN ISOLATED RAIN OR SNOW SHOWER TO POP UP BUT NOT MUCH MORE THAN THAT. LOW TEMPERATURES SHOULD REMAIN ABOVE FREEZING ALONG THE COAST WITH SOUTHWEST WINDS AHEAD OF THE FRONT. COLD FRONT LOOKS TO MOVE THROUGH THE REGION ON THURSDAY. NAM SEEMS WAY TO FAST WITH THE FRONT COMPARED TO THE GFS/ECMWF. THEREFORE...EXPECT MUCH OF THE REGION TO RECOVER WELL INTO THE 40S. NOT MUCH MOISTURE AVAILABLE WITH THE APPROACHING COLD FRONT. WILL GO WITH A SLIGHT CHANCE POP FOR AN ISOLATED RAIN OR SNOW SHOWER. MUCH COLDER AIR WILL MOVE IN BEHIND THE FRONT THURSDAY NIGHT. LOWS SHOULD FALL INTO THE TEENS ACROSS THE INTERIOR...WITH 20S ALONG THE COASTAL PLAIN. HIGHS ON FRIDAY SHOULD BE JUST IN THE 30S AND PORTIONS OF THE HIGHER TERRAIN MAY SEE HIGHS ONLY IN THE UPPER 20S. MOST OF THE MODELS AGREE ON A SECONDARY STORM DEVELOPING ALONG THE DEPARTING COLD FRONT THURSDAY NIGHT AND FRIDAY. HOWEVER...THE CANADIAN/GFS/ECMWF AND THE GFS ENSEMBLES HAVE THIS OCCURRING WELL EAST OF OUR REGION. THEREFORE...WE ARE EXPECTING FRIDAY AND SATURDAY TO BE DRY. HOWEVER...THE UKMET IS A BIT CLOSER AND INDICATES WE MIGHT BE BRUSHED BY THE STORM. THE UKMET HAS SHOWN THIS FOR SEVERAL RUNS IN A ROW...BUT THIS LATEST 00Z RUN HAS TRENDED FURTHER EAST AND MORE PROGRESSIVE. THINGS CAN CHANGE THIS FAR OUT...BUT THE MOSTLY LIKELY SCENARIO IS THAT WE WILL BE DRY AND NOT IMPACTED BY THE COASTAL STORM LATE IN THE WEEK. OTHERWISE...LOOKS LIKE TEMPERATURES WILL BEGIN TO MODERATE EARLY NEXT WEEK AS THE NORTHEAST TROUGH IS REPLACED BY ZONAL FLOW. HIGH TEMPERATURES SHOULD RECOVER WELL INTO THE 40S ON SUNDAY. AVIATION... CONDITIONS WILL LOWER TO MVFR AS FAR INLAND AS KPVD AND KBOS TERMINAL AREAS...WITH A PERIOD OF IFR CONDITIONS PROBABLE NEAR S COAST THIS MORNING. PRECIPITATION TYPE WILL BE ALL RAIN FROM ISLANDS ONTO S COAST...AND INITIALLY A RAIN/SNOW MIX FOR KBOS/KPVD WHICH WILL CHANGE TO ALL SNOW AROUND 12Z. HEIGHT OF THIS EVENT WILL BE IN 11Z- 15Z TIMEFRAME FOR COASTAL TERMINALS. IT WILL REMAIN VFR FARTHER INLAND WHERE CEILINGS SHOULD ONLY LOWER TO 4KFT THIS MORNING. RAPID CLEARING WILL TAKE PLACE BEHIND SYSTEM STARTING IN CT VALLEY 14-15Z AND ON COASTAL PLAIN 16-17Z. NW WINDS WILL GUST TO 25-30KT FROM LATER THIS MORNING INTO EARLY THIS EVENING AS LOW DEEPENS OFFSHORE. MARINE... GALE WARNINGS REMAIN POSTED FOR NANTUCKET SOUND AND FOR OUTER WATERS... WHERE NW WINDS WILL RAPIDLY INCREASE AROUND MID MORNING AS LOW PASSES E OF NEW ENGLAND AND DEEPENS. ELSEWHERE WE HAVE SMALL CRAFT ADVISORIES ISSUED FOR 25 TO 30KT GUSTS. WINDS WILL CONTINUE TO GUST TO AROUND 25 KT THROUGH TONIGHT...THOUGH THEY WILL SUBSIDE LATE TONIGHT NEAR COAST. WINDS AND SEAS WILL DIMINISH TUE. LOW LEVEL JET OF 45 TO 55 KNOTS WILL DEVELOP WEDNESDAY AFTERNOON AND EVENING. EVEN THOUGH ITS WARM ADVECTION ON SOUTHWEST WINDS...THE AIR WILL BE COLDER THAN OUR CURRENT OCEAN WATER TEMPERATURES. THEREFORE...WE EXPECT STRONG SCA OR MARGINAL GALE FORCE WIND GUSTS WEDNESDAY AFTERNOON AND NIGHT. STRONG SCA WILL ALSO PROBABLY NEEDED THURSDAY AND FRIDAY...WITH COLD ADVECTION BEHIND THE COLD FRONT. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...GALE WARNING FOR ANZ231-232-250-254-255 FROM 1 PM MONDAY TO 7 PM MONDAY. ...SMALL CRAFT ADVISORY FOR ANZ230-233>237 FROM 10 AM MONDAY TO 6 AM TUESDAY. && $$ MESOSCALE UPDATE...FRANK SHORT TERM...JWD LONG TERM...FRANK ma AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1104 PM EST MON DEC 4 2006 .UPDATE... HEAVY LES IS THE MAIN CONCERN TONIGHT FOR PORTIONS OF WEST AND NORTH CENTRAL UPPER MICHIGAN. NUMEROUS MESOLOWS OVER LAKE SUPERIOR THIS EVENING AS NOTED ON IR SATELLITE IMAGERY AND THE KMQT RADAR HAVE MOVED ONSHORE INTO ONTONAGON...HOUGHTON AND ALGER COUNTIES. SPOTTER REPORTS OF 5" OR MORE FROM PAINESDALE TO TWIN LAKES AND FROM GREENLAND TO ONTONAGON HAS PROMPTED THE ISSUANCE OF A LES ADVISORY THROUGH TONIGHT AS MESOSCALE MODELS INDICATE LES BANDS COULD LINGER OVER THESE LOCATION INTO THE EARLY OVERNIGHT HOURS. ANOTHER MESOLOW MOVING ONSHORE INTO ALGER COUNTY SHOULD ADD A FEW MORE INCHES TO EVENING SNOWFALL TOTALS THERE AND RESULT IN ADVISORY CRITERIA SNOWS OF 3 TO 6 INCHES. THEREFORE...HOISTED AN LES ADVISORY THERE AS WELL. THOUGHT ABOUT ISSUING AN ADVISORY FOR MQT COUNTY BUT AFTER CALLING AROUND THE AREA...MOST LOCATIONS HAD PICKED UP NO MORE THAN AN INCH OR TWO. IT LOOKS LIKE SNOW SHOULD BE WINDING DOWN TOO OVER MQT COUNTY AS ONSHORE NRLY FLOW HAS DEVELOPED OVER ERN LAKE SUPERIOR. THIS WILL ELIMINATE ENVIRONMENT FOR MID-LAKE CONVERGENCE BANDS/MESOLOWS AND EXPECT JUST GENERAL LES BANDS OVERNIGHT WITH NAM BUFR SNDGS INDICATING INVERSION HGTS LOWERING TO AROUND 4KFT. MENTIONED LOCAL SNOWFALL AMOUNTS OF UP TO 4 INCHES OVER ERN MQT COUNTY. ELSEWHERE...NO CHANGES MADE TO GOING FCST. && .PREV DISCUSSION... .SHORT TERM... IN THE SHORT TERM (TONIGHT)...MAIN FCST ISSUE IS LES OFF LAKE SUPERIOR. LES TONIGHT WILL REVOLVE AROUND EVOLUTION OF CONVERGENCE ZONES/MESOLOWS EVIDENT ON VIS SATELLITE IMAGERY. MAIN CONVERGENCE ZONE RUNS FROM JUST NORTH OF DEVILS ISLAND TO NEAR THE TIP OF THE KEWEENAW THEN ALMOST DUE E ACROSS THE LAKE. IT IS CLEARLY MARKED BY LES ON VIS SATELLITE IMAGERY AND IS BEGINNING TO ACCELERATE S. SMALL KINKS/POSSIBLE MESOLOWS ARE EMBEDDED IN THE BAND. LES HAS RECENTLY REACHED COPPER HARBOR...AND WEB CAM SHOWS HVY SNOW FALLING THERE. TO THE SE...BROADER LOW PRESSURE APPEARS TO BE ORGANIZING OVER SE LAKE SUPERIOR PER GENERAL CYCLONIC ROTATION OF ECHOES ON 0.5 DEGREE REFLECTIVITY IMAGERY FROM KMQT RADAR. ONCE AGAIN...THE REGIONAL CANADIAN MODEL APPEARS TO HAVE THE BEST HANDLE ON THE WIND FIELDS OVER LAKE SUPERIOR THIS AFTN. 18Z RUC13 SUPPORTS ITS SOLUTION...BUT WHAT EVENTUALLY TRANSPIRES OVER SE LAKE SUPERIOR WILL BE A PROBLEM. 18Z RUC13 INDICATES MESOLOW BECOMING NEARLY STATIONARY JUST OFF PICTURED ROCKS BEFORE DRIFTING BACK TO THE N LATE TONIGHT. HOWEVER...WILL FOLLOW BULK OF OTHER GUIDANCE WHICH SHOWS CONVERGENCE ZONE SWEEPING S TO THE SHORELINE. GENERAL SUBSIDENCE IN THE WAKE OF SHORTWAVE AND SHIFTING WINDS WHICH WILL KEEP LES BANDS ON THE MOVE SHOULD KEEP THIS FROM BECOMING A WIDESPREAD ADVY TYPE EVENT. NONETHELESS...BRIEF HVY SNOW WILL OCCUR AS FOCUSED CONVERGENCE ZONES PASS. LES INTENSITY WILL BE AIDED BY HIGH INVERSIONS AROUND 7KFT...AND ZONE OF FAVORABLE DENDRITIC SNOW GROWTH TEMPS COINCIDENT WITH LOW-LEVEL UPWARD MOTION MAX. AREAS FROM NEAR KIWD THRU THE KEWEENAW...AND ALGER/PORTIONS OF LUCE COUNTY WILL SEE THE HEAVIEST SNOW AND HAVE GONE WITH GENERAL 2-4 INCH ACCUMULATIONS IN THOSE AREAS. IF A MESOLOW DOES MEANDER NEAR THE ALGER COUNTY SHORELINE...HEADLINES WILL BE NEEDED AS FOCUSED CONVERGENCE WILL YIELD PERSISTENT MDT/HVY SNOW. WILL ALSO NEED TO WATCH THE AREA AROUND HOUGHTON COUNTY AND ONTONAGON COUNTY FOR CONVERGENCE WHICH MAY BECOME FOCUSED LATER TONIGHT AS LAND BREEZES STRENGTHEN. AT THIS TIME...THERE DOESN'T APPEAR TO BE A SUFFICIENT NRLY PUSH TO BRING MAIN BAND OF SNOW COMPLETELY INTO MARQUETTE COUNTY. AREAS FROM BIG BAY TO MARQUETTE AND E TOWARD SHOT POINT SHOULD GET GRAZED THOUGH AND WILL INCLUDE LOCAL 1-2 INCH ACCUMULATIONS THERE. .LONG TERM... THE MAIN FORECAST CONCERN IS THE POTENTIAL FOR SNOW OVER THE NEXT FEW DAYS. TONIGHT...LOW PRESSURE CIRCULATING OVER THE U.P. THIS AFTERNOON WILL MOVE EASTWARD OVER LAKE HURON TONIGHT. NW WINDS WILL PICK UP BEHIND THE LOW...AND WITH SUBSTANTIAL MOISTURE UP TO 800MB...GOING WITH DEFINITE POPS ALONG THE LAKE EFFECT FAVORED AREAS...ESPECIALLY OVER THE KEWEENAW AND NORTHERN ALGER COUNTY. TUE-THU... WINDS EXPECTED TO BACK WEST BY 12Z TUE AND SW BY 18Z...CUTTING OFF THE BEST CHANCE OF LES IN THE NORTH AND EAST...AND TAPERING OFF THE LES OVER THE KEWEENAW EARLY IN THE MORNING. KEEPING LIKELY POPS OVER LAKE SUPERIOR FOR LINGERING LES THROUGH TUE AFTERNOON. SSW WINDS OVER LAKE MI MAY BRING LES TO PARTS OF SOUTHERN SCHOOLCRAFT CO...SO UPPED SNOW AMT TO AROUND 3 INCHES TO BLEND WITH APX. IF THE WINDS BECOME TOO WESTERLY...WILL NEED TO DECREASE THIS EXPECTED SNOW AMT FOR OUR CWA. MEANWHILE AROUND 18Z...280-300K ISENTROPIC ASCENT WILL OCCUR OVER THE WESTERN U.P. AS A WARM FRONT EXTENDING FROM THE SFC LOW PRES NEAR THE MN/ND BORDER APPROACHES OUR CWA FROM THE CENTRAL MIDWEST. WITH THIS ASCENT...MOISTURE WILL SLOWLY ADVECT INTO THE CWA AND EAT AWAY AT THE DRY AIR IN PLACE. WITH SUFFICIENT MOISTURE AND FRONTOGENESIS FROM A PASSING COLD FRONT...PUT LIKELY POPS OVER WESTERN 1/4 CWA BY 18Z TUE AND PROGRESSED THE LIKELY AREA EASTWARD THROUGH TUE NIGHT. HPC FAVORS A BLEND OF THE 00Z GFS AND ECMWF AND MANY OF THE OTHER MODELS ARE IN LINE WITH EACH OTHER...WITH THE EXCEPTION OF THE 00Z UKMET. THE GFS HAS TRENDED SLOWER WITH THE PROGRESSION OF THIS FRONTAL BOUNDARY ACROSS OUR CWA...BUT SPED UP A LITTLE WITH THE 12Z RUN. TRENDED THE LIKELY POPS SLOWER THAN WHAT WAS ORIGINALLY IN GRIDS...BUT MAY HAVE GONE A LITTLE TOO SLOW. WILL NEED TO KEEP AN EYE ON THE PROJECTED SPEED OF THIS SYSTEM. WITH STRONG NW WINDS BEHIND THE COLD FRONT...EXPECTING LIKELY SNOW ALONG THE WESTERN CWA LAKESHORE AND UPPER MI EAST OF MQT. 850MB TEMPS AROUND -18C OR LESS BETWEEN 18Z WED AND 18Z THU. LOOKING FOR LES CONDITIONS TO LINGER THROUGH THU AND TAPER OFF BY THU NIGHT. EXTENDED DISCUSSION (FRI-MON)... NO MAJOR CHANGES TO TEMPS DAYS 4-7. HIGH PRESSURE WILL BE IN CONTROL OVER THE CENTRAL U.S. THROUGH THE WEEKEND. A SERIES OF SHORTWAVES WILL CROSS LAKE SUPERIOR DURING THIS PERIOD...BRINGING A CHANCE OF PCPN TO THE FAR NORTHERN PART OF OUR CWA. HOWEVER FOR NOW...KEEPING SLIGHT CHANCE POPS MAINLY NORTH OF THE LAND...CLOSELY FOLLOWING HPC AND THE GFS. BY SUN AFTERNOON AND MON...BROUGHT SLIGHT CHANCE INTO WESTERN CWA AND KEWEENAW COUNTY TO ACCOUNT FOR BETTER ISENTROPIC LIFT AHEAD OF A COLD FRONT. THE WEAK FRONT IS EXPECTED TO PASS THROUGH THE CWA MON 00Z-06Z ACCORDING TO THE GFS. EXTREME ARCTIC TEMPS BEHIND THE FRONT DO NOT LOOK PROMISING ATTM. && .MQT WATCHES/WARNINGS/ADVISORIES...LAKE EFFECT SNOW ADVISORY FOR MIZ002-003-006 UNTIL 10Z TUE. && $$ VOSS (UPDATE) ROLFSON (SHORT TERM) MRC (LONG TERM) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 950 PM EST MON DEC 04 2006 .UPDATE...WATER VAPOR IMAGERY REVEALING MID LEVEL SHORT WAVE SLIDING THROUGH THE STATE TO THE SOUTH WHILE MAIN SYNOPTIC FORCING/MOISTURE PUSHING OFF ACROSS LAKE HURON. ASSOCIATED SFC LOW PRESSURE SLIDING ACROSS THE NRN LAKE HURON THIS EVENING AS OF 02Z. SHARP LOW LEVEL CYCLONIC FLOW WITH THIS SYSTEM PRODUCED SOME INTERESTING MESOSCALE CIRCULATIONS ON LAKES MICHIGAN AND SUPERIOR DURING THE EVENING ALONG WITH INTENSE POCKETS OF SNOW. MOST NOTABLE CIRCULATION DEVELOPED SOUTH OF BEAVER ISLAND AND PUSHED ONSHORE NEAR PETOSKEY. VERY HEAVY BANDING OF SNOW WITH THIS FEATURE SET UP ACROSS LITTLE TRAVERSE BAY INTO PETOSKEY AND BAY VIEW AREA AND PRODUCED WHITE OUT CONDITIONS FOR A TIME (PER LOCAL WEBCAMS). NOW TRACKING THIS MESOSCALE CIRCULATION THROUGH NORTH CENTRAL LOWER MICHIGAN PUSHED ALONG BY LOW LEVEL WINDS VEERING INTO THE NW BEHIND THE DEPARTING LOW. FOR THE REST OF TONIGHT...MESOSCALE CIRCULATION OVER NW LOWER MICHIGAN WILL CONTINUE DOWN THROUGH GRAYLING AND MIO AREAS...BUT SHOULD WEAKEN SUBSTANTIALLY HAVING MOVED WELL AWAY FROM LAKE MICHIGAN. THEN...NAM/RUC BOTH FORECAST PRIMARILY NW FLOW FOR A GOOD PORTION OF THE NIGHT BEFORE BACKING WEST TOWARD MORNING. HOWEVER LOOKING UPSTREAM AT MQT RADAR...A COUPLE MORE MESO CIRCULATIONS DROPPING SOUTH OFF SOUTHERN LAKE SUPERIOR AND NOT ENTIRELY SURE JUST WHERE THESE CIRCULATIONS WILL END UP. IF THESE FEATURES EVENTUALLY SWING DOWN INTO NRN LAKE MICHIGAN THEY WOULD CERTAINLY DISRUPT THE FORECAST FLOW REGIME AS WELL AS PRODUCE ADDITIONAL POCKETS OF HEAVY SNOW SHOWERS ALONG THE LAKE MICHIGAN SHORELINE COUNTIES. THESE CIRCULATIONS MAY SIMPLY WEAKEN HAVING MOVED OFF LAKE SUPERIOR AND AWAY FROM THE SHARP TROUGH AXIS ANALYZED BACK ACROSS LAKE SUPERIOR THIS EVENING. TIME WILL TELL. AT ANY RATE...FROM A LAKE EFFECT STANDPOINT...FORECAST SOUNDINGS OVER LAKE MICHIGAN NOT TOO SHABBY AS LAKE-850 MB DELTA T/S HOLD AROUND 20C THROUGH THE NIGHT WITH INVERSIONS 5K FEET MSL OR GREATER. BUT MEANWHILE UNDER INCREASING SUBSIDENCE...INVERSION HEIGHTS STRENGTHEN AND LOWER LATER ON TONIGHT WHILE LOW-MID LEVELS ABOVE THE INVERSION DRY OUT (MEAN 850-700 MB RH DECREASING TO 50 PERCENT OR LESS). COMBINED WITH EVENTUAL BACKING FLOW SHOULD RESULT IN A DOWN TICK IN OVERALL SNOW SHOWER INTENSITY ESPECIALLY AFTER 4 AM OR SO. ASSUMING FLOW REGIME REMAINS MORE OR LESS NW...WILL LIKELY TRIM OUT HEADLINES FROM TIP OF THE MITT COUNTIES (EMMET AND CHEBOYGAN) AS WELL AS MACKINAC COUNTY WITH THE EVENING FORECAST UPDATE. FOR EVERYONE ELSE...GIVEN SNOW ACCUMULATIONS ALREADY REPORTED TODAY AND WITH ANOTHER 6 HOURS OF LIGHT TO MODERATE SNOW SHOWERS ANTICIPATED...WILL KEEP WARNINGS AND ADVISORIES GOING FOR NOW. CONSIDERED ADDING KALKASKA AND CRAWFORD COUNTIES INTO THE ADVISORY MIX GIVEN HEAVIER SNOWFALL THAT WILL MOVE THROUGH WITH THE MESOSCALE CIRCULATION OVER THE NEXT FEW HOURS PLUS SOME ADDITIONAL NW FLOW LAKE EFFECT. BUT THINK THAT ACCUMULATIONS AND CONDITIONS WILL REMAIN SUB ADVISORY. ADAM && .PREV DISCUSSION...ISSUED AT 400 PM EST MON DEC 04 2006 DISCUSSION...ON THE CURRENT SURFACE WEATHER MAP...1015 MB LOW PRESSURE WAS CENTERED ACROSS NORTHERN MICHIGAN WITH 1028 MB HIGH PRESSURE RIDGED ACROSS THE CENTRAL AND NORTHERN PLAINS REGION. CURRENT APX RADAR SHOWED INTENSE SOUTHWEST FLOW LAKE EFFECT BAND HAD MOVED INLAND INTO NORTHWEST LOWER WHILE ADDITIONAL WESTERLY FLOW BANDS WERE FORMING OVER LAKE MICHIGAN. THE MAIN SHORT TERM FORECAST CONCERNS FOR TONIGHT WILL REVOLVE AROUND ONGOING HEADLINES AND ADDITIONAL SNOWFALL ACCUMULATIONS. TONIGHT...SYNOPTIC LIFT/MOISTURE MOVES TO THE EAST OF THE REGION EARLY TONIGHT. THIS WILL LEAVE PURE LAKE EFFECT CONDITIONS. WINDS CONTINUE TO VEER FROM THE WEST TO THE WEST NORTHWEST THIS EVENING TO NORTHWEST BY MIDNIGHT BEFORE BACKING BACK INTO THE WEST NORTHWEST TOWARD MORNING. DELTA TS REMAIN IN THE VERY FAVORABLE RANGE (ABOUT 20) AND 900-700 MB RH (MOISTURE) STARTS OFF BETWEEN 90 AND 95 PERCENT THIS EVENING BEFORE DROPPING DOWN TO BETWEEN 60 AND 65 PERCENT AFTER MIDNIGHT. INVERSION HEIGHTS ARE DECENT AT BETWEEN 4000 AND 5000 FEET. THE ONE NEGATIVE IS THAT WINDS ARE SHIFTING AROUND TONIGHT WHICH MAY LIMIT BANDS FROM FOCUSING IN ON ONE AREA FOR TO LONG (UNLIKE TODAY). OVERALL 2 TO 4 INCHES OF ADDITIONAL SNOW IS EXPECTED IN WNW AND NW FLOW FAVORED LOCALS AND LESS THAN AN INCH ELSEWHERE. CURRENT HEADLINES WILL CONTINUE OVERNIGHT BUT WILL ADD OTSEGO COUNTY INTO THE ADVISORY. MACKINAC COUNTY MAY BE ABLE TO BE CANCELLED EARLY (OVER A FOOT OF SNOW FELL DURING A FEW HOUR PERIOD FROM ST. IGNACE TO MORAN EARLIER TODAY). LOWS TONIGHT WILL BE MAINLY IN THE TEENS. SULLIVAN LONGER TERM ISSUES (TUESDAY THROUGH MONDAY)...COLD PATTERN TO REMAIN IN PLACE FOR MUCH OF THE COMING WEEK WITH MEAN LONG WAVE TROUGHING ANCHORED OVER EASTERN NORTH AMERICA. THIS QUICK TRANSITION TOWARD A +PNA PATTERN EXPECTED TO BREAK DOWN THIS WEEKEND AS WESTERN RIDGE FLATTENS OUT AND HEIGHTS RISE ACROSS THE GREAT LAKES. A COUPLE OF CLIPPER SYSTEMS REINFORCING THE MEAN EASTERN TROUGH WILL PROVIDE THE PRIMARY FORECAST PROBLEMS FOR A BUSY MIDWEEK PERIOD...AS THEY USHER IN THE COLDEST AIR OF THE SEASON THUS FAR WITH ASSOCIATED LAKE EFFECT/ LAKE ENHANCED SNOWFALL POTENTIAL. TUESDAY...AT THE ONSET TUESDAY WILL BE ONGOING LES IN THE WAKE OF TODAY'S CLIPPER...WHILE WAITING FOR THE NEXT ONE IN THE SERIES WHICH WILL BE SPREADING SNOWFALL ACROSS THE UPPER MIDWEST DURING THE DAY. THE MAIN BRUNT OF THIS NEXT SYSTEM SHOULD BEGIN TO IMPACT THE AREA DURING THE MID/LATE AFTERNOON HOURS...WITH THE MAIN SHOW OCCURRING TUESDAY NIGHT. LOW LEVEL WINDS FORECAST TO BACK SHARPLY SOUTHWEST DURING THE MORNING HOURS AHEAD OF APPROACHING SHORT WAVE TROUGH. SO LINGERING WEST-NORTHWEST ORIENTED SNOWBANDS SHOULD ROTATE SOUTHWEST AND IMPACT PRIMARILY FAR NORTHWEST LOWER AND THE SOUTHERN SHORE OF THE UPPER PENINSULA BY LATE MORNING AND AFTERNOON. WARMING 850MB TEMPERATURES (ABOVE -8C BY AFTERNOON)/LOWERING INVERSION HEIGHTS (BELOW 850MB) AND DRYING ABOVE THE INVERSION EXPECTED TO LIMIT INTENSITY OF LES...HARD TO SEE MORE THAN AN INCH OR TWO IN FAVORED SOUTHWEST FLOW AREAS. SYNOPTIC CONTRIBUTION THEN ARRIVES LATE IN THE AFTERNOON AND DURING THE EVENING HOURS. SOME DIFFERENCES IN THE GUIDANCE REGARDING ENDING TIME OF BEST SYNOPTIC SUPPORT...WILL LEAN SLIGHTLY TOWARD THE QUICKER NAM AS THE GFS IS TRENDING IN THAT DIRECTION...BUT WON'T ADD TIMING SPECIFICS TO THE FORECAST AT THIS POINT (MORE OF A MIDDLE OF THE ROAD APPROACH). NICE SHOT OF DEEP LAYER QG FORCING AND ISENTROPIC ASCENT SPREAD ACROSS THE FORECAST AREA...LOOKS LIKE ALL AREAS WILL GET IN ON SOME MEASURABLE SNOWFALL AND CAN ENVISION A SWATH OF 2-4 INCH SNOWFALL ACROSS MOST OF NORTHERN MI. BUT SOUTHWEST FLOW LAKE ENHANCEMENT WILL AGAIN BE A PLAYER ADJACENT TO LAKE MICHIGAN/FAR NORTHERN LAKE HURON. NOT EXPECTED TO SEE INSTABILITY TO THE EXTENT SEEN THIS AFTERNOON (INVERSION HEIGHTS ABOUT 100MB LOWER OR SO)...BUT SHOULD BE ENOUGH TO PUSH ACCUMULATIONS INTO WARNING CRITERIA (6-8 INCHES) WEST OF US-131 OVER NORTHWEST LOWER AS WELL AS ACROSS FAR SOUTHEAST UPPER MI. BRISK SOUTH/SOUTHWEST WINDS LIKELY GUSTING IN THE 20-30 MPH RANGE WILL ALSO BE AN ISSUE REGARDING BLOWING/DRIFTING SNOW. GIVEN THE PLETHORA OF HEADLINES ALREADY IN EFFECT FOR THESE SAME AREAS... WILL REFRAIN FROM ISSUING A WINTER STORM WATCH AT THIS POINT TO MINIMIZE THE CHAOS. GALE WARNINGS WILL BE HOISTED FOR LAKE MICHIGAN NEARSHORE ZONES FOR TUESDAY NIGHT. WEDNESDAY...LOOKING AT WEDNESDAY TO BE A TRANSITION BACK TOWARD NORTHWEST FLOW LES...TIMING OF WHICH IS SOMEWHAT UNCERTAIN GIVEN VARIATIONS IN FORECAST TIMING OF COLD FRONTAL PASSAGE. WOULD EXPECT A BAND OF SNOW ALIGNED ALONG THE COLD FRONT TO PASS ACROSS THE AREA DURING THE EARLY/MID MORNING HOURS...AND WITH 850MB TEMPERATURES DROPPING BACK BELOW -15C DURING THE DAY EXPECTING MORE PERSISTENT NORTHWEST FLOW TO SET UP BY AFTERNOON. BEST ACCUMULATIONS DURING THE DAY LOOK TO BE ACROSS CHIPPEWA COUNTY WHERE FETCH WILL BE MOST PERSISTENT ALONG WITH THE BEST INSTABILITY. INVERSION HEIGHTS WILL CONTINUE TO RISE OVERNIGHT AS LAST WAVE IN THE SERIES DROPS IN FROM THE NORTH ALONG WITH THE POOL OF COLDEST AIR (850MB TEMPERATURES HEADING TOWARD -20C). SO LOOKING FOR LES TO CONTINUE...WITH BANDS VEERING MORE NORTH-NORTHWEST AS THE NIGHT WEARS ON. SEVERAL MORE INCHES LIKELY IN THIS REGIME. EXTENDED PERIODS (THURSDAY THROUGH MONDAY)...EXTENDED FORECAST PERIOD WILL START WITH THE CORE OF THE COLDEST AIR CROSSING THE WESTERN LAKES THURSDAY...850MB TEMPERATURES BELOW -16C WILL ENSURE CONTINUED SNOW SHOWER ACTIVITY ESPECIALLY IN LOCATIONS FAVORED BY NORTHWEST FLOW. AS HEIGHTS BEGIN TO RISE WARM ADVECTION SETS UP IN EARNEST FRIDAY...MAY BE ENOUGH PACIFIC MOISTURE LEFT OVER TO WRING OUT SOME LIGHT PRECIP THOUGH LOW LEVEL RETURN FLOW SHOULD BE DRY. CURRENT FORECAST IS DRY AND WILL KEEP IT THAT WAY FOR THE TIME BEING. FOR THE WEEKEND SPLIT FLOW DEVELOPS ACROSS THE WEST...LOOKS LIKE A DRY PATTERN THROUGH SUNDAY WITH A CONTINUED MODERATING TREND IN TEMPERATURES. SOME HINTS OF A SOUTHERN BRANCH SHORT WAVE TROUGH LIFTING NORTHEAST FOR MONDAY THAT COULD BRING A CHANCE OF SNOW FOR THE BEGINNING OF NEXT WEEK. AS FOR TEMPERATURES...THURSDAY STARTS OUT COLD WITH HIGHS A SOLID 10+ DEGREES BELOW EARLY DECEMBER NORMALS...A FEW AREAS STRUGGLING TO GET OUT OF THE TEENS NOT OUT OF THE QUESTION. MODERATING TRENDS SHOULD REALLY KICK IN BY SATURDAY AS TEMPERATURES CLIMB BACK ABOVE FREEZING...PERHAPS EVEN A 40 DEGREE READING ESPECIALLY BY SUNDAY. JPB && .APX...WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING THROUGH TONIGHT... MIZ019>021-025-031 LAKE EFFECT SNOW ADVISORY THROUGH TONIGHT... MIZ008-022 GALE WARNING...TUESDAY NIGHT...LMZ323-341-342-344-345. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 911 PM EST MON DEC 4 2006 .UPDATE... ZONE FORECASTS/GRIDS HAVE BEEN TWEAKED VERY SLIGHTLY FOR THE OVERNIGHT. LIGHT SNOW PATTERN CONTINUES TO SLOWLY WANE AND IS PRESENTLY MAINLY CONFINED TO SOUTH OF I 69. FOR MOST OF THE REMAINING OVERNIGHT PERIOD...HAVE BOOSTED THE POPS FOR THE COUNTIES NEAR THE OH BORDER...AND LATEST MESOSCALE MODELS SEEM TO CONCENTRATE BEST SNOWFALL/BANDING TO SOUTHERN HALF OF FORECAST AREA OVERNIGHT...AND ESPECIALLY NEAR AND SOUTH OF I 94...GENERALLY SUGGESTIVE OF 1 TO 3 INCHES 12 HOUR SNOWFALL ENDING BY 12Z TUESDAY FOR MOST OF SOUTHERN HALF OF SOUTHEAST MI. THEREFORE...NO OTHER SIGNIFICANT CHANGES WERE MADE...AND ZONE FORECAST WORDING HAS BEEN REFRESHED. && .PREV DISCUSSION...ISSUED 700 PM EST MON DEC 4 2006 AVIATION... A SLOW WANING IN OVERALL RADAR REFLECTIVITY RETURNS SEEN EARLY THIS EVENING AS INITIAL VORTICITY IMPULSE ALOFT SLIDES OFF TO THE EAST. CHALLENGE TONIGHT AGAIN CENTERS ON DEGREE OF LAKE MI EFFECT SNOW SHOWERS THROUGH THE OVERNIGHT AND LOCATION OF BEST BANDING. 18Z MODEL RUNS AND LATEST RUC SUPPORT MODEST WEST TO EAST WIND CONVERGENCE BAND SETTING UP MAINLY CENTRAL COUNTIES OF SOUTHEAST MI BY LATE EVENING THEN SLIGHTLY SETTLING SOUTHWARD OVERNIGHT. BEST 950 MB CONVERGENCE/OMEGA ASCENT CONSENSUS TENDING TO SHOW UP CENTERED OVERNIGHT SOMEWHERE IN THE VICINITY OF M 59. TAFS REFLECT FLAKES IN THE AIR AT TAF SITES MOST OF THE TIME OVERNIGHT...WITH LOWEST VISIBILITIES IN SNOW SHOWERS VERY EARLY EVENING TO ACCOUNT FOR LEFTOVER WIDESPREAD SNOW AND AGAIN MIDNIGHT INTO EARLY MORNING HOURS WITH MORE IN WAY OF LAKE EFFECT BANDING. EXPECT SOMEWHAT OF A BREAK FROM SNOW TUESDAY ESPECIALLY IN THE AFTERNOON...AS LOW LEVEL RIDGE TRAVERSES THE AREA. TAFS REFLECT MOSTLY MVFR CEILINGS...THOUGH PARTICULARLY THIS EVENING WILL SEE PERIODS OF VFR...AS WELL AS TUESDAY AFTERNOON WHEN 1000/850 MB WINDS TURN TO SOUTHWEST IN WARM ADVECTION REGIME. VISIBILITIES OCCASIONALLY MVFR THROUGH THE NIGHT...AND LOCAL IFR. PREV DISCUSSION...ISSUED 357 PM EST MON DEC 4 2006 SHORT TERM...TONIGHT AND TUESDAY .LAKE EFFECT SNOW BANDING WILL BE THE MAIN CONCERN TONIGHT... POTENT UPPER WAVE WAS OVER SOUTHEAST LOWER MICHIGAN THIS AFTERNOON AND PROVIDING THE REGION WITH SYNOPTIC AND LAKE ENHANCED SNOWFALL. VISIBILITIES HAVE DROPPED BACK TO AROUND 1 MILE IN THE HEAVIER SNOWFALL BUT SNOWFLAKE SIZE REMAIN RATHER SMALL AND ACCUMULATIONS HAVE REMAINED LIGHT (< 1"). THIS SYSTEM WILL TRACK EAST THIS EVENING AND WE WILL TRANSITION TOWARD A MORE PURE LAKE EFFECT OVERNIGHT. BUFKIT SOUNDINGS AND POINT SOUNDINGS FROM THE GFS/NAM SHOW INVERSION HEIGHTS QUICKLY CLIMBING BETWEEN 725-800MB AND IMPRESSIVE LOW LEVEL LAPSE RATES DEVELOPING. TRAJECTORIES WILL AVERAGE AROUND 270 DEGREES THROUGH MOST OF THIS EVENING AND IMPACT THE M59-I96 CORRIDOR THEN WINDS VEER TOWARD 290-300 DEGREES OVERNIGHT; THIS WILL PLACE BAND(S) OF SNOW CLOSER TO I96-I94 OVERNIGHT. DUE TO THE TRANSITORY NATURE OF THESE BANDS...WILL PLACE THE HIGHER ACCUMULATIONS OF SNOW FOR LIVINGSTON/WASHTENAW COUNTIES WITH A 1-3" AND 1" OR LESS ELSEWHERE. THIS WILL NEED TO BE MONITORED VERY CLOSELY AS LOCALLY HIGHER AMOUNTS ARE POSSIBLE (MAINLY ALONG THE M59 CORRIDOR AND TOWARD ARB-DTW). LATEST 18Z NAM/RUC AND EXPERIMENTAL 12Z WRF OUTPUT POINT TOWARD A MORE INTENSE BAND BETWEEN 05-09Z AND EVENING SHIFT WILL MONITOR TRENDS. INVERSION HEIGHTS DROP UPSTREAM LATE TONIGHT AS WARM ADVECTION OCCURS UPSTREAM AND SURFACE RIDGE CRESTS OVER LAKE MICHIGAN AROUND SUNRISE. THIS WILL REDUCE THE LAKE BAND INTENSITIES ACROSS SOUTHEAST LOWER AND KEEP THE BANDS RIGHT NEAR THE SHORELINE BEFORE DISSIPATING DURING THE MORNING. THEN ABUNDANCE OF DRY AIR MOVES ACROSS THE LOWER HALF OF THE STATE BUT THIS WILL BE SHORT LIVED AS NEXT CLIPPER IS ON THE WAY. AN INCREASE IN HIGH AND MID LEVEL MOISTURE WILL TAKE PLACE. ISENTROPIC LIFT AND LOWERING CPD/S WILL COMMENCE RATHER QUICKLY IN THE AFTERNOON AND THE TRI CITIES MIGHT BE CLOSE ENOUGH FOR THE CHANCE OF LIGHT SNOW IN THE LATE AFTERNOON. TEMPERATURES MAY STRUGGLE ONCE AGAIN TO CLIMB TOWARD THE FREEZING MARK AWAY FROM METRO DTW. LONG TERM... THE 12Z MODELS ARE CLUSTERING TOWARD A FASTER SOLUTION ON THE SHORT WAVE AND COLD FRONT EXPECTED IN OUR AREA LATE TUESDAY NIGHT AND WEDNESDAY. THIS LOOKS GOOD BASED ON SATELLITE IMAGERY THIS AFTERNOON SHOWING THE WAVE ALONG THE CANADIAN WEST COAST SHEARING INLAND ON THE SOUTH END WITH A DISTINCT CIRCULATION NEARLY INTO THE CANADIAN ROCKIES. ADJUSTMENTS TO THE FORECAST IN THIS REGARD WILL BRING LIKELY POPS INTO THE OVERNIGHT PERIOD TUESDAY NIGHT AND THROUGH WEDNESDAY MORNING, THEN TAPERING THINGS OFF WEDNESDAY AFTERNOON AS THE FRONT MOVES THROUGH SE MICHIGAN BY EVENING. THE INITIAL SHOT OF ISENTROPIC LIFT AHEAD OF THE WAVE TUESDAY NIGHT STILL LOOKS ON THE DRY SIDE JUDGING FROM MODEL RH FIELDS AND CROSS SECTIONS WITH THE POSSIBLE EXCEPTION OF A DUSTING IN THE TRI CITIES AND NORTHERN THUMB. THE ISENTROPIC LIFT WILL BE ON THE LEADING EDGE OF THE LOW LEVEL THETA-E RIDGE THAT WILL MOVE IN PLACE IN TIME FOR SOME UPPER SUPPORT IN THE FORM OF DCVA FROM THE SHORT BEFORE 12Z WEDNESDAY MORNING. THIS, ALONG WITH FORCING ALONG THE COLD FRONT, WILL LIKELY LEAD TO AN INCH OR TWO OF ACCUMULATION DURING THE DAY ON WEDNESDAY. CLOSE ON THE HEELS OF THE WEDNESDAY SYSTEM, WILL BE ANOTHER UPPER WAVE ARRIVING WEDNESDAY NIGHT AND THURSDAY FROM NORTHERN CANADA. THIS WAVE, ALONG WITH A SYSTEM DIGGING INTO THE GULF OF ALASKA WILL AMPLIFY THE UPPER FLOW AND LEAD TO ANOTHER SHOT OF COLD AIR IN LOWER MICHIGAN. TRENDS IN THE 12Z MODEL DATA INDICATE A MORE MERIDIONAL UPPER FLOW AFTER THE UPPER TROUGH AXIS MOVES THROUGH SE MICHIGAN AND A MORE NORTHERLY LOW LEVEL WIND PATTERN OVER THE LAKES. EXPECT THIS TO BRING SOME LAKE EFFECT SNOW INTO THE THUMB DURING THURSDAY AND THURSDAY NIGHT. THE NORTHERLY FLOW COULD ALSO LEAD TO SOME CLOUD FREE CONDITIONS OVER THE INTERIOR OF LOWER MICHIGAN AND SOME OF THE COLDEST LOW TEMPERATURES SO FAR THIS SEASON. FRIDAY WILL BE A TRANSITION DAY FROM BELOW NORMAL TEMPS TOWARD A WARMING TREND HEADING INTO THE WEEKEND. THE 12Z GFS CONTINUES TO BE FASTER THAN THE OTHER GLOBAL MODELS BUILDING THE RIDGE INTO LOWER MICHIGAN AND TURNING THE WINDS TOWARD THE SW ON FRIDAY. WITH THIS IN MIND, WE WILL SHADE THE FORECAST ON THE COOLER SIDE OF GFS/MEX TEMPERATURE GUIDANCE ON FRIDAY AND THEN CATCH UP WITH ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS FOR SATURDAY AND SUNDAY. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION AND UPDATE...DWD SHORT TERM...BGM LONG TERM....BT YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 700 PM EST MON DEC 4 2006 .AVIATION... A SLOW WANING IN OVERALL RADAR REFLECTIVITY RETURNS SEEN EARLY THIS EVENING AS INITIAL VORTICITY IMPULSE ALOFT SLIDES OFF TO THE EAST. CHALLENGE TONIGHT AGAIN CENTERS ON DEGREE OF LAKE MI EFFECT SNOW SHOWERS THROUGH THE OVERNIGHT AND LOCATION OF BEST BANDING. 18Z MODEL RUNS AND LATEST RUC SUPPORT MODEST WEST TO EAST WIND CONVERGENCE BAND SETTING UP MAINLY CENTRAL COUNTIES OF SOUTHEAST MI BY LATE EVENING THEN SLIGHTLY SETTLING SOUTHWARD OVERNIGHT. BEST 950 MB CONVERGENCE/OMEGA ASCENT CONSENSUS TENDING TO SHOW UP CENTERED OVERNIGHT SOMEWHERE IN THE VICINITY OF M 59. TAFS REFLECT FLAKES IN THE AIR AT TAF SITES MOST OF THE TIME OVERNIGHT...WITH LOWEST VISIBILITIES IN SNOW SHOWERS VERY EARLY EVENING TO ACCOUNT FOR LEFTOVER WIDESPREAD SNOW AND AGAIN MIDNIGHT INTO EARLY MORNING HOURS WITH MORE IN WAY OF LAKE EFFECT BANDING. EXPECT SOMEWHAT OF A BREAK FROM SNOW TUESDAY ESPECIALLY IN THE AFTERNOON...AS LOW LEVEL RIDGE TRAVERSES THE AREA. TAFS REFLECT MOSTLY MVFR CEILINGS...THOUGH PARTICULARLY THIS EVENING WILL SEE PERIODS OF VFR...AS WELL AS TUESDAY AFTERNOON WHEN 1000/850 MB WINDS TURN TO SOUTHWEST IN WARM ADVECTION REGIME. VISIBILITIES OCCASIONALLY MVFR THROUGH THE NIGHT...AND LOCAL IFR. && .PREV DISCUSSION...ISSUED 357 PM EST MON DEC 4 2006 SHORT TERM...TONIGHT AND TUESDAY ..LAKE EFFECT SNOW BANDING WILL BE THE MAIN CONCERN TONIGHT... POTENT UPPER WAVE WAS OVER SOUTHEAST LOWER MICHIGAN THIS AFTERNOON AND PROVIDING THE REGION WITH SYNOPTIC AND LAKE ENHANCED SNOWFALL. VISIBILITIES HAVE DROPPED BACK TO AROUND 1 MILE IN THE HEAVIER SNOWFALL BUT SNOWFLAKE SIZE REMAIN RATHER SMALL AND ACCUMULATIONS HAVE REMAINED LIGHT (< 1"). THIS SYSTEM WILL TRACK EAST THIS EVENING AND WE WILL TRANSITION TOWARD A MORE PURE LAKE EFFECT OVERNIGHT. BUFKIT SOUNDINGS AND POINT SOUNDINGS FROM THE GFS/NAM SHOW INVERSION HEIGHTS QUICKLY CLIMBING BETWEEN 725-800MB AND IMPRESSIVE LOW LEVEL LAPSE RATES DEVELOPING. TRAJECTORIES WILL AVERAGE AROUND 270 DEGREES THROUGH MOST OF THIS EVENING AND IMPACT THE M59-I96 CORRIDOR THEN WINDS VEER TOWARD 290-300 DEGREES OVERNIGHT; THIS WILL PLACE BAND(S) OF SNOW CLOSER TO I96-I94 OVERNIGHT. DUE TO THE TRANSITORY NATURE OF THESE BANDS...WILL PLACE THE HIGHER ACCUMULATIONS OF SNOW FOR LIVINGSTON/WASHTENAW COUNTIES WITH A 1-3" AND 1" OR LESS ELSEWHERE. THIS WILL NEED TO BE MONITORED VERY CLOSELY AS LOCALLY HIGHER AMOUNTS ARE POSSIBLE (MAINLY ALONG THE M59 CORRIDOR AND TOWARD ARB-DTW). LATEST 18Z NAM/RUC AND EXPERIMENTAL 12Z WRF OUTPUT POINT TOWARD A MORE INTENSE BAND BETWEEN 05-09Z AND EVENING SHIFT WILL MONITOR TRENDS. INVERSION HEIGHTS DROP UPSTREAM LATE TONIGHT AS WARM ADVECTION OCCURS UPSTREAM AND SURFACE RIDGE CRESTS OVER LAKE MICHIGAN AROUND SUNRISE. THIS WILL REDUCE THE LAKE BAND INTENSITIES ACROSS SOUTHEAST LOWER AND KEEP THE BANDS RIGHT NEAR THE SHORELINE BEFORE DISSIPATING DURING THE MORNING. THEN ABUNDANCE OF DRY AIR MOVES ACROSS THE LOWER HALF OF THE STATE BUT THIS WILL BE SHORT LIVED AS NEXT CLIPPER IS ON THE WAY. AN INCREASE IN HIGH AND MID LEVEL MOISTURE WILL TAKE PLACE. ISENTROPIC LIFT AND LOWERING CPD/S WILL COMMENCE RATHER QUICKLY IN THE AFTERNOON AND THE TRI CITIES MIGHT BE CLOSE ENOUGH FOR THE CHANCE OF LIGHT SNOW IN THE LATE AFTERNOON. TEMPERATURES MAY STRUGGLE ONCE AGAIN TO CLIMB TOWARD THE FREEZING MARK AWAY FROM METRO DTW. LONG TERM... THE 12Z MODELS ARE CLUSTERING TOWARD A FASTER SOLUTION ON THE SHORT WAVE AND COLD FRONT EXPECTED IN OUR AREA LATE TUESDAY NIGHT AND WEDNESDAY. THIS LOOKS GOOD BASED ON SATELLITE IMAGERY THIS AFTERNOON SHOWING THE WAVE ALONG THE CANADIAN WEST COAST SHEARING INLAND ON THE SOUTH END WITH A DISTINCT CIRCULATION NEARLY INTO THE CANADIAN ROCKIES. ADJUSTMENTS TO THE FORECAST IN THIS REGARD WILL BRING LIKELY POPS INTO THE OVERNIGHT PERIOD TUESDAY NIGHT AND THROUGH WEDNESDAY MORNING, THEN TAPERING THINGS OFF WEDNESDAY AFTERNOON AS THE FRONT MOVES THROUGH SE MICHIGAN BY EVENING. THE INITIAL SHOT OF ISENTROPIC LIFT AHEAD OF THE WAVE TUESDAY NIGHT STILL LOOKS ON THE DRY SIDE JUDGING FROM MODEL RH FIELDS AND CROSS SECTIONS WITH THE POSSIBLE EXCEPTION OF A DUSTING IN THE TRI CITIES AND NORTHERN THUMB. THE ISENTROPIC LIFT WILL BE ON THE LEADING EDGE OF THE LOW LEVEL THETA-E RIDGE THAT WILL MOVE IN PLACE IN TIME FOR SOME UPPER SUPPORT IN THE FORM OF DCVA FROM THE SHORT BEFORE 12Z WEDNESDAY MORNING. THIS, ALONG WITH FORCING ALONG THE COLD FRONT, WILL LIKELY LEAD TO AN INCH OR TWO OF ACCUMULATION DURING THE DAY ON WEDNESDAY. CLOSE ON THE HEELS OF THE WEDNESDAY SYSTEM, WILL BE ANOTHER UPPER WAVE ARRIVING WEDNESDAY NIGHT AND THURSDAY FROM NORTHERN CANADA. THIS WAVE, ALONG WITH A SYSTEM DIGGING INTO THE GULF OF ALASKA WILL AMPLIFY THE UPPER FLOW AND LEAD TO ANOTHER SHOT OF COLD AIR IN LOWER MICHIGAN. TRENDS IN THE 12Z MODEL DATA INDICATE A MORE MERIDIONAL UPPER FLOW AFTER THE UPPER TROUGH AXIS MOVES THROUGH SE MICHIGAN AND A MORE NORTHERLY LOW LEVEL WIND PATTERN OVER THE LAKES. EXPECT THIS TO BRING SOME LAKE EFFECT SNOW INTO THE THUMB DURING THURSDAY AND THURSDAY NIGHT. THE NORTHERLY FLOW COULD ALSO LEAD TO SOME CLOUD FREE CONDITIONS OVER THE INTERIOR OF LOWER MICHIGAN AND SOME OF THE COLDEST LOW TEMPERATURES SO FAR THIS SEASON. FRIDAY WILL BE A TRANSITION DAY FROM BELOW NORMAL TEMPS TOWARD A WARMING TREND HEADING INTO THE WEEKEND. THE 12Z GFS CONTINUES TO BE FASTER THAN THE OTHER GLOBAL MODELS BUILDING THE RIDGE INTO LOWER MICHIGAN AND TURNING THE WINDS TOWARD THE SW ON FRIDAY. WITH THIS IN MIND, WE WILL SHADE THE FORECAST ON THE COOLER SIDE OF GFS/MEX TEMPERATURE GUIDANCE ON FRIDAY AND THEN CATCH UP WITH ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS FOR SATURDAY AND SUNDAY. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION...DWD SHORT TERM...BGM LONG TERM....BT YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 457 PM EST MON DEC 4 2006 .SHORT TERM... IN THE SHORT TERM (TONIGHT)...MAIN FCST ISSUE IS LES OFF LAKE SUPERIOR. LES TONIGHT WILL REVOLVE AROUND EVOLUTION OF CONVERGENCE ZONES/MESOLOWS EVIDENT ON VIS SATELLITE IMAGERY. MAIN CONVERGENCE ZONE RUNS FROM JUST NORTH OF DEVILS ISLAND TO NEAR THE TIP OF THE KEWEENAW THEN ALMOST DUE E ACROSS THE LAKE. IT IS CLEARLY MARKED BY LES ON VIS SATELLITE IMAGERY AND IS BEGINNING TO ACCELERATE S. SMALL KINKS/POSSIBLE MESOLOWS ARE EMBEDDED IN THE BAND. LES HAS RECENTLY REACHED COPPER HARBOR...AND WEB CAM SHOWS HVY SNOW FALLING THERE. TO THE SE...BROADER LOW PRESSURE APPEARS TO BE ORGANIZING OVER SE LAKE SUPERIOR PER GENERAL CYCLONIC ROTATION OF ECHOES ON 0.5 DEGREE REFLECTIVITY IMAGERY FROM KMQT RADAR. ONCE AGAIN...THE REGIONAL CANADIAN MODEL APPEARS TO HAVE THE BEST HANDLE ON THE WIND FIELDS OVER LAKE SUPERIOR THIS AFTN. 18Z RUC13 SUPPORTS ITS SOLUTION...BUT WHAT EVENTUALLY TRANSPIRES OVER SE LAKE SUPERIOR WILL BE A PROBLEM. 18Z RUC13 INDICATES MESOLOW BECOMING NEARLY STATIONARY JUST OFF PICTURED ROCKS BEFORE DRIFTING BACK TO THE N LATE TONIGHT. HOWEVER...WILL FOLLOW BULK OF OTHER GUIDANCE WHICH SHOWS CONVERGENCE ZONE SWEEPING S TO THE SHORELINE. GENERAL SUBSIDENCE IN THE WAKE OF SHORTWAVE AND SHIFTING WINDS WHICH WILL KEEP LES BANDS ON THE MOVE SHOULD KEEP THIS FROM BECOMING A WIDESPREAD ADVY TYPE EVENT. NONETHELESS...BRIEF HVY SNOW WILL OCCUR AS FOCUSED CONVERGENCE ZONES PASS. LES INTENSITY WILL BE AIDED BY HIGH INVERSIONS AROUND 7KFT...AND ZONE OF FAVORABLE DENDRITIC SNOW GROWTH TEMPS COINCIDENT WITH LOW-LEVEL UPWARD MOTION MAX. AREAS FROM NEAR KIWD THRU THE KEWEENAW...AND ALGER/PORTIONS OF LUCE COUNTY WILL SEE THE HEAVIEST SNOW AND HAVE GONE WITH GENERAL 2-4 INCH ACCUMULATIONS IN THOSE AREAS. IF A MESOLOW DOES MEANDER NEAR THE ALGER COUNTY SHORELINE...HEADLINES WILL BE NEEDED AS FOCUSED CONVERGENCE WILL YIELD PERSISTENT MDT/HVY SNOW. WILL ALSO NEED TO WATCH THE AREA AROUND HOUGHTON COUNTY AND ONTONAGON COUNTY FOR CONVERGENCE WHICH MAY BECOME FOCUSED LATER TONIGHT AS LAND BREEZES STRENGTHEN. AT THIS TIME...THERE DOESN'T APPEAR TO BE A SUFFICIENT NRLY PUSH TO BRING MAIN BAND OF SNOW COMPLETELY INTO MARQUETTE COUNTY. AREAS FROM BIG BAY TO MARQUETTE AND E TOWARD SHOT POINT SHOULD GET GRAZED THOUGH AND WILL INCLUDE LOCAL 1-2 INCH ACCUMULATIONS THERE. .LONG TERM... THE MAIN FORECAST CONCERN IS THE POTENTIAL FOR SNOW OVER THE NEXT FEW DAYS. TONIGHT...LOW PRESSURE CIRCULATING OVER THE U.P. THIS AFTERNOON WILL MOVE EASTWARD OVER LAKE HURON TONIGHT. NW WINDS WILL PICK UP BEHIND THE LOW...AND WITH SUBSTANTIAL MOISTURE UP TO 800MB...GOING WITH DEFINITE POPS ALONG THE LAKE EFFECT FAVORED AREAS...ESPECIALLY OVER THE KEWEENAW AND NORTHERN ALGER COUNTY. TUE-THU... WINDS EXPECTED TO BACK WEST BY 12Z TUE AND SW BY 18Z...CUTTING OFF THE BEST CHANCE OF LES IN THE NORTH AND EAST...AND TAPERING OFF THE LES OVER THE KEWEENAW EARLY IN THE MORNING. KEEPING LIKELY POPS OVER LAKE SUPERIOR FOR LINGERING LES THROUGH TUE AFTERNOON. SSW WINDS OVER LAKE MI MAY BRING LES TO PARTS OF SOUTHERN SCHOOLCRAFT CO...SO UPPED SNOW AMT TO AROUND 3 INCHES TO BLEND WITH APX. IF THE WINDS BECOME TOO WESTERLY...WILL NEED TO DECREASE THIS EXPECTED SNOW AMT FOR OUR CWA. MEANWHILE AROUND 18Z...280-300K ISENTROPIC ASCENT WILL OCCUR OVER THE WESTERN U.P. AS A WARM FRONT EXTENDING FROM THE SFC LOW PRES NEAR THE MN/ND BORDER APPROACHES OUR CWA FROM THE CENTRAL MIDWEST. WITH THIS ASCENT...MOISTURE WILL SLOWLY ADVECT INTO THE CWA AND EAT AWAY AT THE DRY AIR IN PLACE. WITH SUFFICIENT MOISTURE AND FRONTOGENESIS FROM A PASSING COLD FRONT...PUT LIKELY POPS OVER WESTERN 1/4 CWA BY 18Z TUE AND PROGRESSED THE LIKELY AREA EASTWARD THROUGH TUE NIGHT. HPC FAVORS A BLEND OF THE 00Z GFS AND ECMWF AND MANY OF THE OTHER MODELS ARE IN LINE WITH EACH OTHER...WITH THE EXCEPTION OF THE 00Z UKMET. THE GFS HAS TRENDED SLOWER WITH THE PROGRESSION OF THIS FRONTAL BOUNDARY ACROSS OUR CWA...BUT SPED UP A LITTLE WITH THE 12Z RUN. TRENDED THE LIKELY POPS SLOWER THAN WHAT WAS ORIGINALLY IN GRIDS...BUT MAY HAVE GONE A LITTLE TOO SLOW. WILL NEED TO KEEP AN EYE ON THE PROJECTED SPEED OF THIS SYSTEM. WITH STRONG NW WINDS BEHIND THE COLD FRONT...EXPECTING LIKELY SNOW ALONG THE WESTERN CWA LAKESHORE AND UPPER MI EAST OF MQT. 850MB TEMPS AROUND -18C OR LESS BETWEEN 18Z WED AND 18Z THU. LOOKING FOR LES CONDITIONS TO LINGER THROUGH THU AND TAPER OFF BY THU NIGHT. EXTENDED DISCUSSION (FRI-MON)... NO MAJOR CHANGES TO TEMPS DAYS 4-7. HIGH PRESSURE WILL BE IN CONTROL OVER THE CENTRAL U.S. THROUGH THE WEEKEND. A SERIES OF SHORTWAVES WILL CROSS LAKE SUPERIOR DURING THIS PERIOD...BRINGING A CHANCE OF PCPN TO THE FAR NORTHERN PART OF OUR CWA. HOWEVER FOR NOW...KEEPING SLIGHT CHANCE POPS MAINLY NORTH OF THE LAND...CLOSELY FOLLOWING HPC AND THE GFS. BY SUN AFTERNOON AND MON...BROUGHT SLIGHT CHANCE INTO WESTERN CWA AND KEWEENAW COUNTY TO ACCOUNT FOR BETTER ISENTROPIC LIFT AHEAD OF A COLD FRONT. THE WEAK FRONT IS EXPECTED TO PASS THROUGH THE CWA MON 00Z-06Z ACCORDING TO THE GFS. EXTREME ARCTIC TEMPS BEHIND THE FRONT DO NOT LOOK PROMISING ATTM. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ ROLFSON (SHORT TERM) MRC (LONG TERM) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 357 PM EST MON DEC 4 2006 .SHORT TERM...TONIGHT AND TUESDAY ...LAKE EFFECT SNOW BANDING WILL BE THE MAIN CONCERN TONIGHT... POTENT UPPER WAVE WAS OVER SOUTHEAST LOWER MICHIGAN THIS AFTERNOON AND PROVIDING THE REGION WITH SYNOPTIC AND LAKE ENHANCED SNOWFALL. VISIBILITIES HAVE DROPPED BACK TO AROUND 1 MILE IN THE HEAVIER SNOWFALL BUT SNOWFLAKE SIZE REMAIN RATHER SMALL AND ACCUMULATIONS HAVE REMAINED LIGHT (< 1"). THIS SYSTEM WILL TRACK EAST THIS EVENING AND WE WILL TRANSITION TOWARD A MORE PURE LAKE EFFECT OVERNIGHT. BUFKIT SOUNDINGS AND POINT SOUNDINGS FROM THE GFS/NAM SHOW INVERSION HEIGHTS QUICKLY CLIMBING BETWEEN 725-800MB AND IMPRESSIVE LOW LEVEL LAPSE RATES DEVELOPING. TRAJECTORIES WILL AVERAGE AROUND 270 DEGREES THROUGH MOST OF THIS EVENING AND IMPACT THE M59-I96 CORRIDOR THEN WINDS VEER TOWARD 290-300 DEGREES OVERNIGHT; THIS WILL PLACE BAND(S) OF SNOW CLOSER TO I96-I94 OVERNIGHT. DUE TO THE TRANSITORY NATURE OF THESE BANDS...WILL PLACE THE HIGHER ACCUMULATIONS OF SNOW FOR LIVINGSTON/WASHTENAW COUNTIES WITH A 1-3" AND 1" OR LESS ELSEWHERE. THIS WILL NEED TO BE MONITORED VERY CLOSELY AS LOCALLY HIGHER AMOUNTS ARE POSSIBLE (MAINLY ALONG THE M59 CORRIDOR AND TOWARD ARB-DTW). LATEST 18Z NAM/RUC AND EXPERIMENTAL 12Z WRF OUTPUT POINT TOWARD A MORE INTENSE BAND BETWEEN 05-09Z AND EVENING SHIFT WILL MONITOR TRENDS. INVERSION HEIGHTS DROP UPSTREAM LATE TONIGHT AS WARM ADVECTION OCCURS UPSTREAM AND SURFACE RIDGE CRESTS OVER LAKE MICHIGAN AROUND SUNRISE. THIS WILL REDUCE THE LAKE BAND INTENSITIES ACROSS SOUTHEAST LOWER AND KEEP THE BANDS RIGHT NEAR THE SHORELINE BEFORE DISSIPATING DURING THE MORNING. THEN ABUNDANCE OF DRY AIR MOVES ACROSS THE LOWER HALF OF THE STATE BUT THIS WILL BE SHORT LIVED AS NEXT CLIPPER IS ON THE WAY. AN INCREASE IN HIGH AND MID LEVEL MOISTURE WILL TAKE PLACE. ISENTROPIC LIFT AND LOWERING CPD/S WILL COMMENCE RATHER QUICKLY IN THE AFTERNOON AND THE TRI CITIES MIGHT BE CLOSE ENOUGH FOR THE CHANCE OF LIGHT SNOW IN THE LATE AFTERNOON. TEMPERATURES MAY STRUGGLE ONCE AGAIN TO CLIMB TOWARD THE FREEZING MARK AWAY FROM METRO DTW. && .LONG TERM... THE 12Z MODELS ARE CLUSTERING TOWARD A FASTER SOLUTION ON THE SHORT WAVE AND COLD FRONT EXPECTED IN OUR AREA LATE TUESDAY NIGHT AND WEDNESDAY. THIS LOOKS GOOD BASED ON SATELLITE IMAGERY THIS AFTERNOON SHOWING THE WAVE ALONG THE CANADIAN WEST COAST SHEARING INLAND ON THE SOUTH END WITH A DISTINCT CIRCULATION NEARLY INTO THE CANADIAN ROCKIES. ADJUSTMENTS TO THE FORECAST IN THIS REGARD WILL BRING LIKELY POPS INTO THE OVERNIGHT PERIOD TUESDAY NIGHT AND THROUGH WEDNESDAY MORNING, THEN TAPERING THINGS OFF WEDNESDAY AFTERNOON AS THE FRONT MOVES THROUGH SE MICHIGAN BY EVENING. THE INITIAL SHOT OF ISENTROPIC LIFT AHEAD OF THE WAVE TUESDAY NIGHT STILL LOOKS ON THE DRY SIDE JUDGING FROM MODEL RH FIELDS AND CROSS SECTIONS WITH THE POSSIBLE EXCEPTION OF A DUSTING IN THE TRI CITIES AND NORTHERN THUMB. THE ISENTROPIC LIFT WILL BE ON THE LEADING EDGE OF THE LOW LEVEL THETA-E RIDGE THAT WILL MOVE IN PLACE IN TIME FOR SOME UPPER SUPPORT IN THE FORM OF DCVA FROM THE SHORT BEFORE 12Z WEDNESDAY MORNING. THIS, ALONG WITH FORCING ALONG THE COLD FRONT, WILL LIKELY LEAD TO AN INCH OR TWO OF ACCUMULATION DURING THE DAY ON WEDNESDAY. CLOSE ON THE HEELS OF THE WEDNESDAY SYSTEM, WILL BE ANOTHER UPPER WAVE ARRIVING WEDNESDAY NIGHT AND THURSDAY FROM NORTHERN CANADA. THIS WAVE, ALONG WITH A SYSTEM DIGGING INTO THE GULF OF ALASKA WILL AMPLIFY THE UPPER FLOW AND LEAD TO ANOTHER SHOT OF COLD AIR IN LOWER MICHIGAN. TRENDS IN THE 12Z MODEL DATA INDICATE A MORE MERIDIONAL UPPER FLOW AFTER THE UPPER TROUGH AXIS MOVES THROUGH SE MICHIGAN AND A MORE NORTHERLY LOW LEVEL WIND PATTERN OVER THE LAKES. EXPECT THIS TO BRING SOME LAKE EFFECT SNOW INTO THE THUMB DURING THURSDAY AND THURSDAY NIGHT. THE NORTHERLY FLOW COULD ALSO LEAD TO SOME CLOUD FREE CONDITIONS OVER THE INTERIOR OF LOWER MICHIGAN AND SOME OF THE COLDEST LOW TEMPERATURES SO FAR THIS SEASON. FRIDAY WILL BE A TRANSITION DAY FROM BELOW NORMAL TEMPS TOWARD A WARMING TREND HEADING INTO THE WEEKEND. THE 12Z GFS CONTINUES TO BE FASTER THAN THE OTHER GLOBAL MODELS BUILDING THE RIDGE INTO LOWER MICHIGAN AND TURNING THE WINDS TOWARD THE SW ON FRIDAY. WITH THIS IN MIND, WE WILL SHADE THE FORECAST ON THE COOLER SIDE OF GFS/MEX TEMPERATURE GUIDANCE ON FRIDAY AND THEN CATCH UP WITH ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS FOR SATURDAY AND SUNDAY. && .PREV DISCUSSION...ISSUED 1237 PM EST MON DEC 4 2006 AVIATION... ANOTHER TOUGH AVIATION FORECAST WITH RESPECT TO SNOW AND ITS ASSOCIATED REDUCTIONS TO VISIBILITIES. POTENT UPPER WAVE AND FAVORABLE POSITION OF THE UPPER JET ALONG WITH LAKE MICHIGAN CONTRIBUTION WILL PROVIDE A GENERAL WIDESPREAD LIGHT SNOW WITH A 3-5SM AND MVFR CEILINGS. LATER TONIGHT...WITH THE PASSAGE OF THIS WAVE...IMPRESSIVE CLIMBING OF THE INVERSION HEIGHTS AND STEEP LAPSE RATES WILL BRING AN ACTIVE LAKE EFFECT SNOW PATTERN ACROSS THE REGION. 12Z NAM SUGGESTS A BAND OF SNOW WILL EXTEND ACROSS M59-I69 CORRIDORS THIS EVENING THEN MIGRATE SOUTH OVERNIGHT TOWARD DTW/DET. WE WILL NEED TO MONITOR TRENDS AS THIS COULD PROVIDE A BRIEF 1 MILE OR LESS IN SNOW AND DEPOSIT A LIGHT ACCUMULATION OVERNIGHT. AT THIS POINT WILL BRING VISIBILITIES DOWN TOWARD 1-2 MILES IN A TEMPO GROUP. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...BGM LONG TERM....BT AVIATION...BGM YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1042 AM EST MON DEC 4 2006 .UPDATE... WATER VAPOR IMAGERY/RUC ANALYSIS AND 12Z RAOBS SHOW 110KT JET FROM SRN MN TO SRN WI...SUPPORTING SHORTWAVE DIVING SE ACROSS NRN WI ATTM. MAIN AREA OF SNOW ASSOCIATED WITH JET STREAK/SHORTWAVE IS PASSING THRU ERN WI WHERE WAA/ISENTROPIC ASCENT/DEEP LAYER QVECTOR CONVERGENCE IS STRONGEST. FORCING COMBINED WITH 850MB TEMPS AROUND -14C IS LEADING TO LAKE ENHANCED SNOW IN THE WSW FLOW ACROSS NRN LAKE MICHIGAN AND BAY OF GREEN BAY. NRN FRINGE OF THE ENHANCED SNOW IS JUST BRUSHING THE GARDEN PENINSULA/SRN SCHOOLCRAFT COUNTY AND FAR SE LUCE COUNTY. AT THE SFC...ONCE AGAIN A SHARP CONVERGENCE ZONE HAS SETUP ACROSS LAKE SUPERIOR. N OR NW WINDS ARE NOTED JUST OFF THE NSHORE OF MN WITH NE WINDS ACROSS ISLE ROYALE/NRN LAKE SUPERIOR TRANSITIONING TO SE WINDS TOWARD WHITEFISH BAY. SW WINDS ARE THE RULE ACROSS THE REST OF LAKE SUPERIOR. KDLH RADAR INDICATES A BAND OF MDT LES ALONG THE MAIN CONVERGENCE ZONE OFFSHORE OF MN. ALREADY UPDATED FCST TO INCLUDE SOME MINOR ACCUMULATIONS AROUND 1 INCH FOR THE LAKE ENHANCED SNOW MOVING ONSHORE FROM LAKE MICHIGAN. WINDS WILL BE GRADUALLY VEERING MORE WRLY EARLY THIS AFTN...SO SHORT DURATION COMBINED WITH MAIN ENHANCED SNOW REMAINING JUST SE OF FCST AREA WILL LIMIT ACCUMULATIONS. OTHERWISE...WITH SHORTWAVE QUICKLY DROPPING SE...SUBSIDENCE WILL BE OVERSPREADING UPPER MI DURING THE AFTN...BRINGING A DIMINISHING TREND TO THE GENERAL -SN ACROSS THE FCST AREA. NEXT CONCERN IS EVOLUTION OF WIND FIELD OVER LAKE SUPERIOR AND ASSOCIATED LES. MOST OF THE MODELS...ESPECIALLY THE HIGH RESOLUTION MODELS...INDICATE ONE OR TWO ILL-DEFINED MESOLOWS DEVELOPING ALONG CONVERGENCE ZONE AS IT DRIFTS SE. MOVEMENT SHOULD BE QUICK ENOUGH OVER THE W TO BRING SOME LES ONSHORE THERE LATER IN THE AFTN. SUBSIDENCE OVERSPREADING THE AREA BEHIND SHORTWAVE BY THE TIME LES IN THE CONVERGENCE ZONE ARRIVES SHOULD WORK TO KEEP ACCUMULATIONS UNDER CONTROL. MIGHT SEE A FEW INCHES OF SNOW THIS AFTN/TONIGHT IN A FEW SPOTS DEPENDING ON HOW THE CONVERGENCE SETS UP AS IT ARRIVES ALONG THE SHORE. && .PREV DISCUSSION... ISSUED AT 353 AM EST THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR MORE SNOW. WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW OVER THE LAKE OF THE WOODS AREA ROTATING THROUGH THE BASE OF A LONGWAVE TROUGH WHICH BLANKETS MUCH OF EASTERN NORTH AMERICA. STRONGEST Q-VECTOR CONVERGENCE IS FOCUSED OVER EASTERN MINNESOTA AND WESTERN WISCONSIN. SNOW IS OCCURRING IN THIS AREA...HOWEVER...DUE TO DRYNESS AT THE LOW LEVELS IT MAINLY IN THE FORM OF VIRGA. SURFACE ANALYSIS DEPICTS A LOW ALSO OVER THE LAKE OF THE WOODS AREA WITH A FRONTAL SYSTEM EXTENDING SOUTH THROUGH EASTERN MINNESOTA AND SOUTHWARD INTO EASTERN KANSAS. A RIDGE EXTENDS FROM THE LOWER MISSISSIPPI RIVER VALLEY THROUGH THE WESTERN OHIO RIVER VALLEY AND THE UPPER GREAT LAKES INTO EASTERN ONTARIO. ANOTHER RIDGE IS DEVELOPING OVER EASTERN MONTANA. THE MID LEVEL LOW WILL SHIFT OVER CENTRAL U.P. TODAY DRAWING THE MID LEVEL ENERGIES INTO THE FORECAST AREA. SHORTWAVE ENERGY WILL SWEEP THROUGH NORTHEAST WISCONSIN AND WESTERN U.P. THE STRONGEST ACCOMPANYING 850-500MB Q-VECTOR CONVERGENCE WILL SHIFT INTO LOWER MICHIGAN DURING THE DAY. A THERMAL TROUGH OVER THE AREA WILL HAVE AN 850MB TEMPERATURES AROUND -16C OVER THE CENTRAL U.P. BY LATE AFTERNOON. THE SURFACE LOW WILL ALSO SWEEP INTO CENTRAL U.P. TODAY. THE WINDS WILL BE BACKING SOUTHWEST EARLY THIS MORNING. WRF INDICATES THAT LOW LEVEL CONVERGENCE WILL BECOME NEGLIGIBLE BY MID MORNING OVER THE AREA. THUS EVEN THOUGH THE LOW LEVEL LAPSE RATE SUGGEST LAKE EFFECT SNOWS...THE WINDS AND LOW LEVEL CONVERGENCE WOULD LIMIT PRODUCTION OF LES OVER THE FORECAST AREA. SO PLAN TO DROP THE ADVISORY AND WARNINGS. AS THE MID LEVEL LOW WEAKENS AND SWINGS EAST...ANOTHER WEAK SHORTWAVE ROTATING THROUGH THE BASE OF THE LONGWAVE TROUGH WILL SLIDE INTO THE WESTERN ONTARIO TONIGHT. THE SURFACE LOW WILL MOVE INTO LAKE HURON. MEANWHILE...ANOTHER LOW WILL DEVELOP OVER SOUTHERN MANITOBA WITH A WEAK WARM FRONT STRETCHED INTO NORTHERN PLAINS. THE RIDGE THAT WAS OVER THE FORECAST AREA WILL SETTLE INTO THE SOUTHEASTERN STATES. 850MB TEMPERATURES WILL BE AROUND -14C. MEAN SURFACE-900MB RH WILL BE 80-90 PERCENT. MID LEVELS STABILITY INDICATE MAINLY Q-VECTOR DIVERGENCE OVER THE AREA. THE SURFACE WILLING WILL VEER NORTHWEST AGAIN FOLLOWING THE LOW. STILL THERE SHOULD BE ENOUGH LOW LEVEL INSTABILITY WITH THE LAPSE RATE...NORTHWEST WINDS...AND AVAILABLE MOISTURE TO PRODUCE LES OVER THE AREA WITH THE HEAVIEST AMOUNTS OCCURRING OVER THE SPINE OF THE KEWEENAW PENINSULA AND OVER THE LAKE SHORE AREA EAST OF MARQUETTE. MODELS SHOWING SOME DIFFERENCES ON TIMING OF THE SYSTEMS MOVING THROUGH THE FORECAST AREA WHICH WILL AFFECT THE ONSET OF SIGNIFICANT PRECIPITATION. WILL FAVOR THE MIDDLE OF THE ROAD NCEP ENSEMBLE/ CANADIAN/UKMET COMPROMISE AS SUGGESTED BY HPC FOR TIMING. SHORTWAVE WILL MOVE THROUGH THE FORECAST AREA ON TUESDAY. THE SURFACE LOW WILL MOVE OUT OF THE PLAINS INTO ARROWHEAD OF MINNESOTA DRAGGING THE COLD FRONT INTO CENTRAL MINNESOTA. WINDS AHEAD OF THE FRONT WILL BACK TO THE WEST AND SOUTHWEST. REDUCING LAKE EFFECT SNOWS OVER THE AREA. 850MB TEMPERATURES WILL KEEP THE DELTA-T'S OVER THE LAKE AROUND 15C OVER THE WEST AND 18C OVER THE EAST. WIND DIRECTION WOULD ONLY SUPPORT SIGNIFICANT LES OCCURRING OVER THE KEWEENAW PENINSULA. THE NEXT SYSTEM WILL SLIDE OVER WISCONSIN AND COULD TRIGGER SOME SHOWERS OVER THE WEST SIDE OF THE U.P. SO WILL ADD A CHANCE THERE. THE LOW WILL MOVE INTO EASTERN ONTARIO TUESDAY NIGHT DRAGGING THE COLD FRONT THROUGH THE AREA AND THE WINDS WILL VEER NORTHWEST AGAIN...MAINLY OVER THE WESTERN U.P. ANOTHER SHORTWAVE WILL SWEEP THROUGH THE AREA. COLD AIR WILL AGAIN ADVECT INTO THE AREA FOLLOWING THE FROPA. LOW LEVEL MOISTURE WILL SUPPORT THE DEVELOPMENT OF MORE LAKE EFFECT SNOW SHOWERS OVER THE AREA. MEANWHILE...A HIGH WILL DEVELOP OVER SASKATCHEWAN. ANOTHER MID LEVEL SHORTWAVE WILL SWEEP INTO THE FORECAST AREA ON WEDNESDAY WHILE ROTATING THROUGH THE BASE OF THE LONGWAVE TROUGH. A THERMAL TROUGH SWEEPING THROUGH CENTRAL CANADA WILL MOVE OVER ONTARIO...LOWERING THE 850MB TEMPERATURES OVER LAKE SUPERIOR TO AROUND -20C. THE SURFACE LOW WILL MOVE INTO SOUTHWEST QUEBEC ON WEDNESDAY WHILE THE SOUTHERN CANADIAN HIGH WILL SHIFT INTO NORTH CENTRAL NORTH DAKOTA. WINDS WILL REMAIN MAINLY OUT OF THE NORTHWEST OVER THE FORECAST AREA. THUS EXPECT MORE LAKE EFFECT SNOWS TO SET UP ON WEDNESDAY OVER THE AREAS MOST PRONE TO LES WITH A NORTHWEST FLOW. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ROLFSON (UPDATE) DLG (PREV DISCUSSION) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY ISSUED BY NATIONAL WEATHER SERVICE STATE COLLEGE PA 419 PM EST MON DEC 4 2006 .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... PRIMARY CONCERN IN THE SHORT TERM IS THE POTENTIAL FOR MODERATE TO HEAVY LAKE EFFECT SNOW ACROSS ONEIDA COUNTY TONIGHT INTO EARLY TUESDAY. HIGH RESOLUTION MODEL DATA /12KM NAM AND LOCAL WRF/ ARE QUITE ADAMANT ABOUT PRODUCING A MESOSCALE LES BAND OFF OF LAKE ONTARIO STARTING AROUND 06Z TNT AND PERSISTING THROUGH AT LEAST 15Z TUE. BLYR FLOW WILL GRADUALLY BECOME SWERLY AHEAD OF APPROACHING S/W AND ASSOCIATED CLIPPER-LIKE FEATURE TRANSLATING EWD ACROSS THE UPPER GREAT LAKES. STRONG LLVL CONVERGENCE RESULTING FROM A MESOSCALE BAROCLINIC ZONE WILL INDUCE FAVORABLE UVVEL WITHIN THE PREFERRED SNOW GROWTH REGION ALONG A NARROW WNW-SSE CORRIDOR FROM KFZY TO KUCA AROUND MIDNIGHT...PERSISTING THRU EARLY TUESDAY. IN ADDITION...BOTH HI RES MODELS ALSO DEVELOP WHAT APPEARS TO BE A MESO-LOW WITH ITS OWN VORT CENTER OVER ERN LAKE ONTARIO WITH A WARM FRONTAL-LIKE CONVERGENCE AREA ALIGNED WITH THE AFOREMENTIONED NARROW BAROCLINIC ZONE. ALSO OF NOTE...IS THE 04/12Z RUN OF THE LCL WRF MODEL WHICH GENERATES AS MUCH AS 30+ INCHES SNOW ACCUM INTO WRN OSWEGO CO WITH CLOSE TO A FOOT IN WRN ONEIDA CO. HMM. NEVERTHELESS (AS A START?)...HAVE ISSUED A LAKE EFFECT SNOW ADVISORY FOR ALL OF ONEIDA CO FROM 1AM THRU 10AM TUES WITH ACCUMULATIONS OF 4 TO 7 INCHES. IF THE BAND PERSISTS LONGER AS THE MESOSCALE/HI RES NAM/WRF WOULD INDICATE...AN UPGRADE TO THE STATEMENT MAY BE NEEDED. LES ACTIVITY SHOULD BEGIN TO TAPER OFF TUESDAY NIGHT AS SFC HIGH PRESSURE SLIDES EWD TO THE ATLANTIC SEABOARD AHEAD OF NEXT MID LEVEL TROF AND ASSOCIATED CLIPPER LOW. HAVE STAYED CLOSE TO MAV/MET BLEND FOR TEMPERATURES. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... NEXT SYSTEM APPROACHES SOMETIME WED-THUR WITH LOW CONFIDENCE/HIGH UNCERTAINTY ON THE TIMING...WHICH IS EVIDENCED THE 04/12Z BGM FSU CONFIDENCE GRAPH. INCREASED POPS SLIGHTLY AHEAD OF THIS WAVE BUT OVERALL NOT MUCH CHANGE IN THE EXTNDD PERIODS AND HAVE BASICALLY WENT ALONG WITH HPC GUID WITH BLEND FROM THE MEN/MEX FOR TEMPERATURES. EXPECT LES ACTIVITY AGAIN TO DEVELOP IN THE WAKE OF THIS NEXT WAVE. BEYOND THAT...THE ERN CONUS MEAN TROF BEGINS TO LIFT OUT TOWARD THE WEEKEND AS THE POSITIVE PNA PATTERN BEGINS TO BREAK DOWN AND THE WRN NOAM RIDGE BEGINS TO MOVE EWD. GRADUAL INCREASE H5 HEIGHTS WILL TRANSLATE INTO A SLOW MODERATION IN TEMPERATURES INTO THE WEEKEND. SPLIT FLOW REGIME CONTINUES OVER THE WEST WITH CONFLUENT...MAINLY ZONAL FLOW ACROSS THE EAST BY LATE IN THE WEEKEND. && .AVIATION... SNOW SHOWERS CONTINUE TO CAUSE REDUCED CIG/VIZ PROBLEMS ACROSS THE AREA...MAINLY NORTH OF A LINE FROM MORAVIA TO ONEONTA. RADAR SHOWS A WIDE AREA WITH SOME EMBEDDED HEAVIER BANDS AFFECTING THE REGION FROM ABOUT SYRACUSE TO HAMILTON AND UTICA. RUC AND NAM12 AGREE IN SHUTTING THINGS DOWN PRETTY QUICK BETWEEN 18 AND 21Z AS LOW LEVEL THERMAL TROF PASSES AND WINDS TAKE ON A MORE WEST TO SOUTHWEST FETCH. HOWEVER...PROGS CONTINUE TO SHOW LOW LEVEL MOISTURE HANGING TOUGH SO I DON'T HOLD OUT A LOT OF HOPE FOR RAPID CLEARING. KEPT UCA/SYR MAINLY MVFR OVERNIGHT WITH CEILINGS BEING THE ISSUE ALONG WITH SCATTERED SNOW SHOWERS AS WEAK WARM ADVECTION AHEAD OF THE NEXT SHORTWAVE STARTS TO OVERSPREAD THE FORECAST AREA. THE REST OF THE TERMINALS SHUD BE MAINLY VFR WITH OCCASIONAL PERIODS BELOW 3000/5 IN JUST SCATTERED SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... NY...LAKE EFFECT SNOW ADVISORY FOR NYZ009-037 FROM 1 AM TUESDAY TO 10 AM TUESDAY. PA...NONE. && $$ SHORT TERM...STEINBUGL LONG TERM...STEINBUGL AVIATION...LA CORTE ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 140 PM EST MON DEC 4 2006 .SHORT TERM /TONIGHT THROUGH WEDNESDAY/...HIGH PRES WILL BUILD OVER THE REGION TONIGHT AND TUE THEN MOVE OFFSHORE WED. THIS WILL KEEP SKIES MAINLY CLR AS ATMS REMAINS DRY. WILL BE A COLD NIGHT TONIGHT WITH GOOD RADIATIONAL CONDITIONS...LOWS WILL RANGE FROM UPPER 20S INLAND TO UPR 30S OBX. WL CONT FREEZE WARNING INTERIOR NE CST WHERE WE THINK THERE HAS YET TO BE A FREEZE. TEMPS TUE WILL BE A LITTLE WARMER THAN TODAY WITH HIGHS IN THE LOW TO MID 50S. AS HIGH MOVES OFFSHR WED LOW LVL FLOW WILL BECOME S/SW...THIS COMBINED WITH 850 TEMPS APPROACHING +5C SHLD GIVE HIGHS IN LOWER 60S MANY SPOTS. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...COLD FRONT AND UPR TRF WILL APPROACH FROM THE W WED NIGHT. MDLS SHOW SOME MOISTURE ALONG THE CST SO WILL MAINTAIN SILENT POP 20 CSTL SITES LATER WED NIGHT INTO THU...HOWEVER REALLY NOT EXPECTING MUCH MORE THAN POSS A FEW SPRINKLES. VERY COLD AIR WILL SWEEP IN BEHIND THE FRONT THU NIGHT INTO FRI AND EXPECT HIGHS FRI AND SAT TO HOLD IN THE 40S. FRI NIGHT LOOKS QUITE COLD WITH SOME INLAND SITES FLIRTING WITH 20. FOR SUN AND EARLY NEXT WEEK TEMPS WILL MODERATE QUICKLY AS UPR TRF IS REPLACED WITH WEAK/BROAD RIDGING. && .AVIATION /18Z-18Z/...VFR CONDITIONS SHOULD PREVAIL THRU THE NEXT 24 HOURS UNDER DRY AIRMASS. && .MARINE...TOUGH PART OF FCST IS DURATION OF SCA WINDS/SEAS OVER THE CSTL WATERS. LATEST RUC IS CLOSE TO CURRENT OBSERVATIONS AND HAVE ESSENTIALLY FOLLOWED IT IN THE FIRST 6 TO 8 HOURS. IT SHOWS WINDS SUBSIDING BY 00Z. IT WILL LIKELY TAKES SEAS ABOUT 6 HOURS LONGER OVER THE WATERS N OF OCRACOKE AND WILL CONTINUE SMALL CRAFT ADVISORY NORTH OF OCRACOKE THRU ABOUT MIDNIGHT. ALL OTHER SCA WILL BE DROPPED AT ISSUANCE. AXIS OF STRONG SFC HIGH SHOULD WORK ITS WAY TO THE MID-ATLANTIC COAST BY TUES NIGHT/WEDS WITH LIGHT GRADIENT. THE WINDS WILL PICK BACK UP BY THURSDAY AFTERNOON INTO FRIDAY AS NEXT STRONG COLD FRONT APPROACHES THE AREA. VERY STRONG CAA BEHIND THIS FRONT WITH H8 TEMPS DROPPING TO AS LOW AS -10C...SO WINDS WILL LIKELY HAVE TO BE BUMPED UP OVER THE NEXT FEW DAYS. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 7 AM EST TUESDAY FOR NCZ046-047-081. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR AMZ150-152- 154. && $$ SHORT TERM...FREDERICK LONG TERM...FREDERICK AVIATION...COLLINS MARINE...COLLINS nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 715 PM CST MON DEC 4 2006 .CURRENT OBSERVATIONAL OVERVIEW... 01Z SURFACE ANALYSIS DEPICTED RIDGE AXIS SITUATED OVER THE RED RIVER VALLEY WITH RESULTANT LIGHT AND VARIABLE FLOW. IN WAKE OF AXIS STRONG PRESSURE FALLS WERE NOTED ACROSS THE WESTERN DAKOTAS IN ADVANCE OF NEXT UPSTREAM TROUGH FROM ALBERTA PROVINCE INTO THE NORTHERN ROCKIES. LATEST WATER VAPOR IMAGERY CONTINUED TO SHOW PROGRESSIVE U/L FLOW OVER CONUS WITH S/W ENERGY OVER THE NORTHERN ROCKIES NOTED BY LARGE AREA OF MID/HIGH LEVEL MOISTURE PUNCHING SOUTHEAST FROM MONTANA. .FORECAST DETAILS.(OVERNIGHT)... GFS INITIALIZED WELL WITH SURFACE AND UPPER LEVEL FEATURES AT OOZ... THUS WILL BE INCORPORATED INTO OVERNIGHT FORECAST. PROGRESSIVE PATTERN TO CONTINUE OVER CWFA DURING NEXT 24 AS SURFACE RIDGE SHIFTS TO EAST OF CWFA LATE TONIGHT FOLLOWED BY TROUGH TRAVERSING CWFA ON TUESDAY. OVERNIGHT LOWS MAIN FORECAST CHALLENGE. DEVELOPING VEERING LOW LEVEL WIND PROFILE ALONG WITH AN INCREASE IN MID CLOUDS SHOULD RESULT IN TEMPS BOTTOMING OUT AROUND MIDNIGHT ESPECIALLY FROM THE VALLEY WEST THEN STEADY OR SLOWLY RISING TEMPS EXPECTED THE 2ND HALF OF THE NIGHT. INHERITED FORECAST PRETTY MUCH HAS THIS IDEA IN MIND...THUS ONLY SOME MINOR UPDATES TO HOURLY TEMP TRENDS EXPECTED. IN ADDITION LATEST RUC SHOWS SOME DEVELOPING 700MB ASCENT AHEAD OF TROUGH AFTER MIDNIGHT. THIS COUPLED WITH MARGINAL MOISTURE ADVECTION WARRANTS KEEPING IN SLIGHT POP RISK TOO. SO TO SUM IT UP IN A NUTSHELL APPEARS AS THOUGH ONLY MINOR CHANGES NEEDED. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ BERG nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 953 PM EST MON DEC 4 2006 .SHORT TERM /REST OF TONIGHT/... WARM ADVECTION HAS COMMENCED ACROSS CENTRAL PA UNDER LIMITED MOISTURE. SCATTERED FLURRIES ENTERING WESTERN AREAS ACCORDING TO LATEST METARS...BUT NOT EXPECTING ACCUMULATION OUTSIDE OF MY NORTHWEST COUNTIES AFTER WINDS BACK AROUND TO THE NORTHWEST AND LAKE ENHANCED BANDS ARRIVE. TWEAKED TEMPS SLIGHTLY DOWNWARD ACROSS THE SOUTH CENTRAL MOUNTAINS AND LOWER SUSQ. AS UPSTREAM BINOVC AS PER GOES IR IMAGERY SHOULD ALLOW SLIGHTLY LARGER TEMP RANGES OVERNIGHT. OTHERWISE...ALL OTHER ASPECTS OF GOING FORECAST IN GOOD SHAPE. && .PREV DISCUSSION... /ISSUED 213 PM EST MON DEC 4 2006/ SHORT TERM /TONIGHT THROUGH TUESDAY/... MAIN CONCERN THIS PERIOD WILL BE THE POTENTIAL FOR LAKE EFFECT SNOWS IN THE NW AND HOW MUCH WILL FALL. THE REST OF THE AREA WILL SEE WX IMPROVE THIS EVENING BEFORE LK EFFECT CLOUDS AND PERHAPS SHSN RETURN FOR THE LATE NIGHT AND MORNING. LATEST RUC/NAM/GFS SOLUTIONS ALL POINT TO WIND FIELDS CONTINUING TO BACK THRU 00/03Z...THEN VEERING AROUND TO THE NW AGAIN. AS THE CROSS-LAKE WINDS GET NEARLY PARALLEL LATE TONIGHT AROUND 290 DEGS AND UPLIFT IS MAXIMIZED IN THE 6-10 HOURS AROUND 12Z...WE EXPECT TO SEE SHSN DEVELOP AGAIN IN THE NW. THE FETCH/RESIDENCE TIME OF THE COLD AIR OVER THE LAKE IS NOT ALL THAT LONG...BUT THE TEMPERATURE PROFILE OF THE TOP TWO-THIRDS OF THE CLOUD LAYER AROUND RUSH HOUR IS VERY NEARLY PERFECT FOR MAXIMIZED DENDRITIC CRYSTAL GROWTH AT -10 TO -18C. IN ADDITION...THE UVV/S AS CHARACTERIZED BY THE OMEGA FIELDS IN THE LOWEST 7-10KFT ARE VERY STRONG AT THE SAME TIME. THUS...WE COULD SEE VERY DRAMTIC SNOW RATES AND BAD VISBYS DURING THE EARLY MORNING HOURS. WILL GO FOR SNOW ACCUMS 3-5 INCHES IN WARREN COUNTY. SOME SPOTS IN THE NW CORNER COULD GET 6 OR MORE..BUT NOT COUNTY-WIDE. WILL GO FOR LESSER ACCUMS IN THE ADJACENT COUNTIES/ZONES...BUT STILL LIKELY POPS. SUMMING IT UP...WILL POST A LAKE EFFECT SNOW ADVISORY FOR WARREN COUNTY FOR LATE TONIGHT AND TUESDAY MORNING FOR A TOTAL OF 3-5 INCHES ACROSS THE COUNTY. EVE/MID SHIFTS WILL NEED TO MONITOR FOR POSSIBLY EXPANDING THE ADVSRY TO ADJ AREAS OR EVEN UPGRADING TO A WARNING. MINS TONIGHT WILL BE IN THE TEENS AND LOWER 20S...CLOSE TO GUID. MID 20S TO UPPER 30S WILL BE THE MAXES ON TUES. DOWNSLOPE WARMING AND SUNSHINE SHOULD HELP THE LOWER SUSQ GET CLOSE TO 40. LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... FIRST DAY BACK SINCE MONSTER STORM THAT WRECK HAVOC ON MUCH OF THE COUNTRY THE LATER PART OF LAST WEEK. ANYWAY...OTHER THAN THE FRONT THAT COME IN LAST NIGHT...AND ANOTHER ONE TUE AM...NEXT FRONT WILL BE LATE WED/THU. OVERALL...A MUCH MORE TAME PATTERN...WITH NEAR TO SLIGHTLY BELOW NORMAL TEMPS. MODELS AND HPC HAVE LARGE HIGH BUILDING SOUTHWARD AND EASTWARD FROM THE PLAINS BY THU. DID NOT MAKE MANY CHANGES...DID LOWER TEMPS A LITTLE FROM HPC EARLY ON...GIVEN HOW COLD THE AIR IS. WENT WITH A DRY FCST AFTER 00Z SAT...AS HEIGHTS RISE...AND WINDS SHIFT TO THE W-SW. TEMPS WILL MODERATE INTO EARLY NEXT WEEK. SOME HINTS OF A BIGGER STORM AT SOME POINT...BUT HARD TO SEE ANYTHING AT THIS POINT. AVIATION... MVFR CLOUDS OVER THE NW TAFS /JST+BFD/ SHOULD START TO LIFT SHORTLY AS THE FLOW IS BACKING AND LOWER MOISTURE ADVECTING IN. SOME MID CLOUDS RACING THRU OH ATTM SHOULD BREAK UP A BIT AS THEY GET HERE. SO...A GENERALLY VFR FORECAST THRU 06Z...WHEN FLOW VEERS AGAIN AND BRINGS THE WRN TAFS DOWN...ESP KBFD. KBFD AND KJST MAY SEE PERIODS OF IFR AND LIFR IN THE LATE NIGHT/EARLY MORNING HRS...BTWN 08Z AND 15Z. CIGS AT UNV/IPT/AOO SHOULD DANCE BETWEEN VFR AND MVFR AGAIN IN THE MORNING...BUT THE VSBYS WILL ONLY DIP IF THE SNOW SHOWERS CAN HOLD TOGETHER. THEN THE INVERSION LOWERS A BIT AND FLOW BACKS AGAIN...BRINGING IMPROVEMENT TO THE FLYING WX FOR ALL. KMDT AND POINTS IN THE SE WILL NOT GO BLO VFR CONDITIONS AT ALL THRU THE PERIOD. && .CTP WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY FOR PAZ004 FROM 1 AM TUESDAY TO 1 PM TUESDAY. && $$ SHORT TERM...DEVOIR pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 213 PM EST MON DEC 4 2006 .SHORT TERM /TONIGHT THROUGH TUESDAY/... MAIN CONCERN THIS PERIOD WILL BE THE POTENTIAL FOR LAKE EFFECT SNOWS IN THE NW AND HOW MUCH WILL FALL. THE REST OF THE AREA WILL SEE WX IMPROVE THIS EVENING BEFORE LK EFFECT CLOUDS AND PERHAPS SHSN RETURN FOR THE LATE NIGHT AND MORNING. LATEST RUC/NAM/GFS SOLUTIONS ALL POINT TO WIND FIELDS CONTINUING TO BACK THRU 00/03Z...THEN VEERING AROUND TO THE NW AGAIN. AS THE CROSS-LAKE WINDS GET NEARLY PARALLEL LATE TONIGHT AROUND 290 DEGS AND UPLIFT IS MAXIMIZED IN THE 6-10 HOURS AROUND 12Z...WE EXPECT TO SEE SHSN DEVELOP AGAIN IN THE NW. THE FETCH/RESIDENCE TIME OF THE COLD AIR OVER THE LAKE IS NOT ALL THAT LONG...BUT THE TEMPERATURE PROFILE OF THE TOP TWO-THIRDS OF THE CLOUD LAYER AROUND RUSH HOUR IS VERY NEARLY PERFECT FOR MAXIMIZED DENDRITIC CRYSTAL GROWTH AT -10 TO -18C. IN ADDITION...THE UVV/S AS CHARACTERIZED BY THE OMEGA FIELDS IN THE LOWEST 7-10KFT ARE VERY STRONG AT THE SAME TIME. THUS...WE COULD SEE VERY DRAMTIC SNOW RATES AND BAD VISBYS DURING THE EARLY MORNING HOURS. WILL GO FOR SNOW ACCUMS 3-5 INCHES IN WARREN COUNTY. SOME SPOTS IN THE NW CORNER COULD GET 6 OR MORE..BUT NOT COUNTY-WIDE. WILL GO FOR LESSER ACCUMS IN THE ADJACENT COUNTIES/ZONES...BUT STILL LIKELY POPS. SUMMING IT UP...WILL POST A LAKE EFFECT SNOW ADVISORY FOR WARREN COUNTY FOR LATE TONIGHT AND TUESDAY MORNING FOR A TOTAL OF 3-5 INCHES ACROSS THE COUNTY. EVE/MID SHIFTS WILL NEED TO MONITOR FOR POSSIBLY EXPANDING THE ADVSRY TO ADJ AREAS OR EVEN UPGRADING TO A WARNING. MINS TONIGHT WILL BE IN THE TEENS AND LOWER 20S...CLOSE TO GUID. MID 20S TO UPPER 30S WILL BE THE MAXES ON TUES. DOWNSLOPE WARMING AND SUNSHINE SHOULD HELP THE LOWER SUSQ GET CLOSE TO 40. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... FIRST DAY BACK SINCE MONSTER STORM THAT WRECK HAVOC ON MUCH OF THE COUNTRY THE LATER PART OF LAST WEEK. ANYWAY...OTHER THAN THE FRONT THAT COME IN LAST NIGHT...AND ANOTHER ONE TUE AM...NEXT FRONT WILL BE LATE WED/THU. OVERALL...A MUCH MORE TAME PATTERN...WITH NEAR TO SLIGHTLY BELOW NORMAL TEMPS. MODELS AND HPC HAVE LARGE HIGH BUILDING SOUTHWARD AND EASTWARD FROM THE PLAINS BY THU. DID NOT MAKE MANY CHANGES...DID LOWER TEMPS A LITTLE FROM HPC EARLY ON...GIVEN HOW COLD THE AIR IS. WENT WITH A DRY FCST AFTER 00Z SAT...AS HEIGHTS RISE...AND WINDS SHIFT TO THE W-SW. TEMPS WILL MODERATE INTO EARLY NEXT WEEK. SOME HINTS OF A BIGGER STORM AT SOME POINT...BUT HARD TO SEE ANYTHING AT THIS POINT. && .AVIATION... MVFR CLOUDS OVER THE NW TAFS /JST+BFD/ SHOULD START TO LIFT SHORTLY AS THE FLOW IS BACKING AND LOWER MOISTURE ADVECTING IN. SOME MID CLOUDS RACING THRU OH ATTM SHOULD BREAK UP A BIT AS THEY GET HERE. SO...A GENERALLY VFR FORECAST THRU 06Z...WHEN FLOW VEERS AGAIN AND BRINGS THE WRN TAFS DOWN...ESP KBFD. KBFD AND KJST MAY SEE PERIODS OF IFR AND LIFR IN THE LATE NIGHT/EARLY MORNING HRS...BTWN 08Z AND 15Z. CIGS AT UNV/IPT/AOO SHOULD DANCE BETWEEN VFR AND MVFR AGAIN IN THE MORNING...BUT THE VSBYS WILL ONLY DIP IF THE SNOW SHOWERS CAN HOLD TOGETHER. THEN THE INVERSION LOWERS A BIT AND FLOW BACKS AGAIN...BRINGING IMPROVEMENT TO THE FLYING WX FOR ALL. KMDT AND POINTS IN THE SE WILL NOT GO BLO VFR CONDITIONS AT ALL THRU THE PERIOD. && .CTP WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY FOR PAZ004 FROM 1 AM TUESDAY TO 1 PM TUESDAY. && $$ SHORT TERM...DANGELO LONG TERM...MARTIN AVIATION...DANGELO pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 856 PM EST MON DEC 4 2006 .SHORT TERM /OVERNIGHT/... COMPOSITE RADAR LOOP SHOWING SNOW SHOWER ACTIVITY OVER THE WESTERN SLOPES OF THE GREEN MOUNTAINS AT THIS TIME. EXPECT THIS ACTIVITY TO CONTINUE OVERNIGHT...SO WILL MENTION SOME LOCALIZED SNOW ACCUMULATIONS OVERNIGHT. ELSEWHERE...SNOW SHOWER ACTIVITY HAS EITHER DIMINISHED OR COME TO AN END WITH THE LOSS OF DAYTIME HEATING. HOWEVER...MODELS AND SATELLITE LOOP SHOW A SHORTWAVE OVER THE GREAT LAKES AT THIS TIME THAT WILL MOVE EAST OVERNIGHT AND BE OVER THE REGION EARLY TUESDAY MORNING. THUS...WILL KEEP IN A CHANCE OR SLIGHT CHANCE OF SNOW SHOWERS ACROSS THE REMAINDER OF THE FORECAST AREA OVERNIGHT. WILL UPDATE THE ZONE FORECASTS TO REFLECT THE ABOVE THINKING. && .PREV DISCUSSION... /ISSUED 312 PM EST MON DEC 4 2006/ SHORT TERM /TONIGHT THROUGH THURSDAY/... THERE SHOULD BE TWO MECHANISMS THAT WILL PRODUCE SNOW SHOWERS ACROSS THE AREA THIS AFTERNOON AND TONIGHT. FIRST IS THE STEEP LOW LEVEL LAPSE RATES THAT HAVE DEVELOPED OVER THE AREA AND THIS WILL CONTINUE THROUGH AT LEAST SUNSET. THEN A WELL DEFINED SHORTWAVE TROUGH MOVE EAST ACROSS MICHIGAN WILL CONTINUE TO HEAD TOWARD OUR AREA OVERNIGHT. SYSTEM WILL DAMPEN A BIT AS IT RUNS INTO THE UPPER TROUGH TO THE EAST. HOWEVER...BACKING FLOW TO THE WEST IN ADVANCE OF THIS FEATURE WILL ALLOW FOR MOISTURE FROM THE EASTERN GREAT LAKES TO BE PUSHED INTO OUR AREA...SO THERE SHOULD BE SOME ADDITIONAL THREAT FOR SNOW SHOWERS. WESTERLY FLOW ALOFT WILL PERSIST INTO TUESDAY AND IT APPEARS A LAKE BAND WILL EXIST OFF OF EASTERN LAKE ONTARIO. THE SOUTHERN PORTIONS OF SAINT LAWRENCE AND FRANKLIN COUNTIES IN NEW YORK WILL BE ON THE FRINGE OF THIS BAND AND WILL CONTINUE TO MENTION A CHANCE OF SNOW SHOWERS OVER THIS AREA ON TUESDAY. OTHERWISE... REMAINDER OF THE AREA TO BE DRY. DRY WEATHER IS EXPECTED OVER THE ENTIRE AREA TUESDAY NIGHT AND THE FIRST PART OF WEDNESDAY AS UPPER FLOW BACKS TO THE SOUTHWEST AHEAD OF DEVELOPING UPPER TROUGH OVER THE UPPER MIDWEST. WARM AIR ADVECTION TO TAKE PLACE TO WARM THE AIR MASS AND WEDNESDAY SHOULD BE THE WARMEST DAY. MAIN PRECIPITATION SHOULD BE ASSOCIATED WITH COLD FRONT/850 MB FRONT AND THAT DOES NOT MOVE THROUGH THE AREA UNTIL LATE WEDNESDAY NIGHT/THURSDAY MORNING. WELL DEFINED THERMAL GRADIENT EXISTS AT 850 MB AND THUS FRONTOGENESIS COMBINED WITH LARGE SCALE LIFT ASSOCIATED WITH THE APPROACHING UPPER TROUGH SUGGESTS AN INCREASE IN AREAL COVERAGE OF LIGHT SNOW IS EXPECTED. WILL MENTION LIGHT SNOW LIKELY OVER THE ENTIRE AREA LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. NOT A LOT OF PRECIPITATION...BUT COULD SEE 1-3 INCHES OF SNOW WITH SOME LOCALIZED AMOUNTS TO 4 INCHES. PRESSURE GRADIENT WILL ALSO BE INCREASING ON WEDNESDAY AND WEDNESDAY NIGHT AHEAD OF THE UPPER TROUGH. LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... TRENDS LOOK LIKE A RELATIVELY DRY PERIOD IN THE EXTENDED WITH DRIER NORTHWEST FLOW INITIALLY IN THE PERIOD. COLDEST 850 MB AIR WILL BE OVER THE AREA THURSDAY NIGHT INTO FRIDAY AND WILL HIGHLIGHT THIS IN THE FORECAST. HIGH PRESSURE AND DEVELOPING WESTERLY FLOW SHOULD BEGIN A SLOW WARMING TREND ALONG WITH A DRY PERIOD. THUS WILL NOT MENTION ANY PRECIPITATION AFTER THURSDAY NIGHT AT THIS TIME. AVIATION... LCL IFR DUE TO VSBY 1-3SM IN INSTABILITY SHSN- THROUGH SUNSET THEN MVFR/VFR CIGS THIS EVENING AS ATMOSPHERE STABILIZES. LOW PRESSURE WILL WEAKEN AS IT MOVES ACROSS THE GREAT LAKES TONIGHT THEN DISSIPATES TOMORROW AS IT RUNS INTO A WEAK RIDGE OF HIGH PRESSURE. AS THE LOW MOVES EAST OVERNIGHT...SOME WEAK OVERRUNNING/ADVECTION OF THE LAKE INDUCED CLOUDS AND -SHSN/FLURRIES WILL AFFECT THE AREA GENERALLY AFTER MIDNIGHT INTO THE MORNING HOURS OF TUE. AT THIS TIME HAVE NOT REDUCED CIGS/VSBY AS SYSTEM IS WEAKENING AND LITTLE SYNOPTIC/OROGRAPHIC LIFT INDICATED. RUC SEEMS TO BE HANDLING THE STRENGTH AND AMPLITUDE OF THIS SYSTEM BEST IN THE SHORT TERM WHILE NAM/GFS SEEM TO WASH THE SYSTEM OUT TOO QUICKLY. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SHORT TERM...WGH vt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 312 PM EST MON DEC 4 2006 .SHORT TERM /TONIGHT THROUGH THURSDAY/... THERE SHOULD BE TWO MECHANISMS THAT WILL PRODUCE SNOW SHOWERS ACROSS THE AREA THIS AFTERNOON AND TONIGHT. FIRST IS THE STEEP LOW LEVEL LAPSE RATES THAT HAVE DEVELOPED OVER THE AREA AND THIS WILL CONTINUE THROUGH AT LEAST SUNSET. THEN A WELL DEFINED SHORTWAVE TROUGH MOVE EAST ACROSS MICHIGAN WILL CONTINUE TO HEAD TOWARD OUR AREA OVERNIGHT. SYSTEM WILL DAMPEN A BIT AS IT RUNS INTO THE UPPER TROUGH TO THE EAST. HOWEVER...BACKING FLOW TO THE WEST IN ADVANCE OF THIS FEATURE WILL ALLOW FOR MOISTURE FROM THE EASTERN GREAT LAKES TO BE PUSHED INTO OUR AREA...SO THERE SHOULD BE SOME ADDITIONAL THREAT FOR SNOW SHOWERS. WESTERLY FLOW ALOFT WILL PERSIST INTO TUESDAY AND IT APPEARS A LAKE BAND WILL EXIST OFF OF EASTERN LAKE ONTARIO. THE SOUTHERN PORTIONS OF SAINT LAWRENCE AND FRANKLIN COUNTIES IN NEW YORK WILL BE ON THE FRINGE OF THIS BAND AND WILL CONTINUE TO MENTION A CHANCE OF SNOW SHOWERS OVER THIS AREA ON TUESDAY. OTHERWISE... REMAINDER OF THE AREA TO BE DRY. DRY WEATHER IS EXPECTED OVER THE ENTIRE AREA TUESDAY NIGHT AND THE FIRST PART OF WEDNESDAY AS UPPER FLOW BACKS TO THE SOUTHWEST AHEAD OF DEVELOPING UPPER TROUGH OVER THE UPPER MIDWEST. WARM AIR ADVECTION TO TAKE PLACE TO WARM THE AIR MASS AND WEDNESDAY SHOULD BE THE WARMEST DAY. MAIN PRECIPITATION SHOULD BE ASSOCIATED WITH COLD FRONT/850 MB FRONT AND THAT DOES NOT MOVE THROUGH THE AREA UNTIL LATE WEDNESDAY NIGHT/THURSDAY MORNING. WELL DEFINED THERMAL GRADIENT EXISTS AT 850 MB AND THUS FRONTOGENESIS COMBINED WITH LARGE SCALE LIFT ASSOCIATED WITH THE APPROACHING UPPER TROUGH SUGGESTS AN INCREASE IN AREAL COVERAGE OF LIGHT SNOW IS EXPECTED. WILL MENTION LIGHT SNOW LIKELY OVER THE ENTIRE AREA LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. NOT A LOT OF PRECIPITATION...BUT COULD SEE 1-3 INCHES OF SNOW WITH SOME LOCALIZED AMOUNTS TO 4 INCHES. PRESSURE GRADIENT WILL ALSO BE INCREASING ON WEDNESDAY AND WEDNESDAY NIGHT AHEAD OF THE UPPER TROUGH. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... TRENDS LOOK LIKE A RELATIVELY DRY PERIOD IN THE EXTENDED WITH DRIER NORTHWEST FLOW INITIALLY IN THE PERIOD. COLDEST 850 MB AIR WILL BE OVER THE AREA THURSDAY NIGHT INTO FRIDAY AND WILL HIGHLIGHT THIS IN THE FORECAST. HIGH PRESSURE AND DEVELOPING WESTERLY FLOW SHOULD BEGIN A SLOW WARMING TREND ALONG WITH A DRY PERIOD. THUS WILL NOT MENTION ANY PRECIPITATION AFTER THURSDAY NIGHT AT THIS TIME. && .AVIATION... LCL IFR DUE TO VSBY 1-3SM IN INSTABILITY SHSN- THROUGH SUNSET THEN MVFR/VFR CIGS THIS EVENING AS ATMOSPHERE STABILIZES. LOW PRESSURE WILL WEAKEN AS IT MOVES ACROSS THE GREAT LAKES TONIGHT THEN DISSIPATES TOMORROW AS IT RUNS INTO A WEAK RIDGE OF HIGH PRESSURE. AS THE LOW MOVES EAST OVERNIGHT...SOME WEAK OVERRUNNING/ADVECTION OF THE LAKE INDUCED CLOUDS AND -SHSN/FLURRIES WILL AFFECT THE AREA GENERALLY AFTER MIDNIGHT INTO THE MORNING HOURS OF TUE. AT THIS TIME HAVE NOT REDUCED CIGS/VSBY AS SYSTEM IS WEAKENING AND LITTLE SYNOPTIC/OROGRAPHIC LIFT INDICATED. RUC SEEMS TO BE HANDLING THE STRENGTH AND AMPLITUDE OF THIS SYSTEM BEST IN THE SHORT TERM WHILE NAM/GFS SEEM TO WASH THE SYSTEM OUT TOO QUICKLY. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SHORT/LONG TERM...EVENSON AVIATION...SISSON vt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1151 PM EST MON DEC 4 2006 .AVIATION... AS PER CURRENT TRENDS...06Z TAFS WILL REFLECT VARIABLE MVFR/VFR CEILINGS OVERNIGHT AS LAKE EFFECT SNOW BANDS TRY TO DEVELOP EAST OVER FORECAST AREA...WITH MODEL CONSENSUS FAVORING THIS MAINLY AT KDET/KDTW TAF SITES. MVFR VISIBILITIES...AT WORST...IN SNOW SHOWERS MENTIONED...HOWEVER. AS IN PREVIOUS ISSUANCE...DAYTIME TUESDAY LOOKS TO BE DRY...BECOMING SCATTERED LOW CLOUDS/VFR BY AFTERNOON...AND CONTINUED VFR TUESDAY EVENING WITH DEEP LAYER OF DRY AIR AHEAD OF THE NEXT SYSTEM. && .PREV DISCUSSION...ISSUED 911 PM EST MON DEC 4 2006 UPDATE... ZONE FORECASTS/GRIDS HAVE BEEN TWEAKED VERY SLIGHTLY FOR THE OVERNIGHT. LIGHT SNOW PATTERN CONTINUES TO SLOWLY WANE AND IS PRESENTLY MAINLY CONFINED TO SOUTH OF I 69. FOR MOST OF THE REMAINING OVERNIGHT PERIOD...HAVE BOOSTED THE POPS FOR THE COUNTIES NEAR THE OH BORDER...AND LATEST MESOSCALE MODELS SEEM TO CONCENTRATE BEST SNOWFALL/BANDING TO SOUTHERN HALF OF FORECAST AREA OVERNIGHT...AND ESPECIALLY NEAR AND SOUTH OF I 94...GENERALLY SUGGESTIVE OF 1 TO 3 INCHES 12 HOUR SNOWFALL ENDING BY 12Z TUESDAY FOR MOST OF SOUTHERN HALF OF SOUTHEAST MI. THEREFORE...NO OTHER SIGNIFICANT CHANGES WERE MADE...AND ZONE FORECAST WORDING HAS BEEN REFRESHED. PREV DISCUSSION...ISSUED 357 PM EST MON DEC 4 2006 SHORT TERM...TONIGHT AND TUESDAY LAKE EFFECT SNOW BANDING WILL BE THE MAIN CONCERN TONIGHT... POTENT UPPER WAVE WAS OVER SOUTHEAST LOWER MICHIGAN THIS AFTERNOON AND PROVIDING THE REGION WITH SYNOPTIC AND LAKE ENHANCED SNOWFALL. VISIBILITIES HAVE DROPPED BACK TO AROUND 1 MILE IN THE HEAVIER SNOWFALL BUT SNOWFLAKE SIZE REMAIN RATHER SMALL AND ACCUMULATIONS HAVE REMAINED LIGHT (< 1"). THIS SYSTEM WILL TRACK EAST THIS EVENING AND WE WILL TRANSITION TOWARD A MORE PURE LAKE EFFECT OVERNIGHT. BUFKIT SOUNDINGS AND POINT SOUNDINGS FROM THE GFS/NAM SHOW INVERSION HEIGHTS QUICKLY CLIMBING BETWEEN 725-800MB AND IMPRESSIVE LOW LEVEL LAPSE RATES DEVELOPING. TRAJECTORIES WILL AVERAGE AROUND 270 DEGREES THROUGH MOST OF THIS EVENING AND IMPACT THE M59-I96 CORRIDOR THEN WINDS VEER TOWARD 290-300 DEGREES OVERNIGHT; THIS WILL PLACE BAND(S) OF SNOW CLOSER TO I96-I94 OVERNIGHT. DUE TO THE TRANSITORY NATURE OF THESE BANDS...WILL PLACE THE HIGHER ACCUMULATIONS OF SNOW FOR LIVINGSTON/WASHTENAW COUNTIES WITH A 1-3" AND 1" OR LESS ELSEWHERE. THIS WILL NEED TO BE MONITORED VERY CLOSELY AS LOCALLY HIGHER AMOUNTS ARE POSSIBLE (MAINLY ALONG THE M59 CORRIDOR AND TOWARD ARB-DTW). LATEST 18Z NAM/RUC AND EXPERIMENTAL 12Z WRF OUTPUT POINT TOWARD A MORE INTENSE BAND BETWEEN 05-09Z AND EVENING SHIFT WILL MONITOR TRENDS. INVERSION HEIGHTS DROP UPSTREAM LATE TONIGHT AS WARM ADVECTION OCCURS UPSTREAM AND SURFACE RIDGE CRESTS OVER LAKE MICHIGAN AROUND SUNRISE. THIS WILL REDUCE THE LAKE BAND INTENSITIES ACROSS SOUTHEAST LOWER AND KEEP THE BANDS RIGHT NEAR THE SHORELINE BEFORE DISSIPATING DURING THE MORNING. THEN ABUNDANCE OF DRY AIR MOVES ACROSS THE LOWER HALF OF THE STATE BUT THIS WILL BE SHORT LIVED AS NEXT CLIPPER IS ON THE WAY. AN INCREASE IN HIGH AND MID LEVEL MOISTURE WILL TAKE PLACE. ISENTROPIC LIFT AND LOWERING CPD/S WILL COMMENCE RATHER QUICKLY IN THE AFTERNOON AND THE TRI CITIES MIGHT BE CLOSE ENOUGH FOR THE CHANCE OF LIGHT SNOW IN THE LATE AFTERNOON. TEMPERATURES MAY STRUGGLE ONCE AGAIN TO CLIMB TOWARD THE FREEZING MARK AWAY FROM METRO DTW. LONG TERM... THE 12Z MODELS ARE CLUSTERING TOWARD A FASTER SOLUTION ON THE SHORT WAVE AND COLD FRONT EXPECTED IN OUR AREA LATE TUESDAY NIGHT AND WEDNESDAY. THIS LOOKS GOOD BASED ON SATELLITE IMAGERY THIS AFTERNOON SHOWING THE WAVE ALONG THE CANADIAN WEST COAST SHEARING INLAND ON THE SOUTH END WITH A DISTINCT CIRCULATION NEARLY INTO THE CANADIAN ROCKIES. ADJUSTMENTS TO THE FORECAST IN THIS REGARD WILL BRING LIKELY POPS INTO THE OVERNIGHT PERIOD TUESDAY NIGHT AND THROUGH WEDNESDAY MORNING, THEN TAPERING THINGS OFF WEDNESDAY AFTERNOON AS THE FRONT MOVES THROUGH SE MICHIGAN BY EVENING. THE INITIAL SHOT OF ISENTROPIC LIFT AHEAD OF THE WAVE TUESDAY NIGHT STILL LOOKS ON THE DRY SIDE JUDGING FROM MODEL RH FIELDS AND CROSS SECTIONS WITH THE POSSIBLE EXCEPTION OF A DUSTING IN THE TRI CITIES AND NORTHERN THUMB. THE ISENTROPIC LIFT WILL BE ON THE LEADING EDGE OF THE LOW LEVEL THETA-E RIDGE THAT WILL MOVE IN PLACE IN TIME FOR SOME UPPER SUPPORT IN THE FORM OF DCVA FROM THE SHORT BEFORE 12Z WEDNESDAY MORNING. THIS, ALONG WITH FORCING ALONG THE COLD FRONT, WILL LIKELY LEAD TO AN INCH OR TWO OF ACCUMULATION DURING THE DAY ON WEDNESDAY. CLOSE ON THE HEELS OF THE WEDNESDAY SYSTEM, WILL BE ANOTHER UPPER WAVE ARRIVING WEDNESDAY NIGHT AND THURSDAY FROM NORTHERN CANADA. THIS WAVE, ALONG WITH A SYSTEM DIGGING INTO THE GULF OF ALASKA WILL AMPLIFY THE UPPER FLOW AND LEAD TO ANOTHER SHOT OF COLD AIR IN LOWER MICHIGAN. TRENDS IN THE 12Z MODEL DATA INDICATE A MORE MERIDIONAL UPPER FLOW AFTER THE UPPER TROUGH AXIS MOVES THROUGH SE MICHIGAN AND A MORE NORTHERLY LOW LEVEL WIND PATTERN OVER THE LAKES. EXPECT THIS TO BRING SOME LAKE EFFECT SNOW INTO THE THUMB DURING THURSDAY AND THURSDAY NIGHT. THE NORTHERLY FLOW COULD ALSO LEAD TO SOME CLOUD FREE CONDITIONS OVER THE INTERIOR OF LOWER MICHIGAN AND SOME OF THE COLDEST LOW TEMPERATURES SO FAR THIS SEASON. FRIDAY WILL BE A TRANSITION DAY FROM BELOW NORMAL TEMPS TOWARD A WARMING TREND HEADING INTO THE WEEKEND. THE 12Z GFS CONTINUES TO BE FASTER THAN THE OTHER GLOBAL MODELS BUILDING THE RIDGE INTO LOWER MICHIGAN AND TURNING THE WINDS TOWARD THE SW ON FRIDAY. WITH THIS IN MIND, WE WILL SHADE THE FORECAST ON THE COOLER SIDE OF GFS/MEX TEMPERATURE GUIDANCE ON FRIDAY AND THEN CATCH UP WITH ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS FOR SATURDAY AND SUNDAY. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY...LHZ421...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON...7 PM TUESDAY TO 9 PM WEDNESDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION AND UPDATE...DWD SHORT TERM...BGM LONG TERM....BT YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi