AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE EUREKA CA 505 AM PST MON NOV 24 2008 .SYNOPSIS...A STRONG UPPER LEVEL LOW OFF THE CENTRAL CALIFORNIA COAST WILL SLOWLY MOVE TOWARD SOUTHERN CALIFORNIA TODAY...BRINGING WET WEATHER TO THE REGION TUESDAY AND TUESDAY NIGHT. AFTER A BRIEF BREAK ON WEDNESDAY...A STORM SYSTEM WILL BRING ADDITIONAL RAIN TO NORTHERN CALIFORNIA ON THURSDAY. AFTER THAT HIGH PRESSURE WILL BRING DRIER WEATHER TO THE AREA FOR THE WEEKEND INTO EARLY NEXT WEEK. && .SHORT TERM...TODAY THROUGH WEDNESDAY...SATELLITE IMAGES SHOW A STRONG UPPER TROUGH JUST EAST OF 140 W THIS MORNING WITH SPLITTING FLOW EVIDENT AND AN IMPRESSIVE DRY SLOT EXTENDING NORTH TO SOUTH ALONG THE TROUGH AXIS. MODELS ARE COMING INTO BETTER AGREEMENT WITH THIS FEATURE...BRINGING THE UPPER LOW TOWARD THE COAST...ALTHOUGH WHILE NAM AND GFS BRING AN OPEN WAVE ONSHORE EARLY WEDNESDAY THE ECMWF MAINTAINS A CLOSED LOW CIRCULATION. NEVERTHELESS ALL SOLUTIONS POINT TOWARD A DECENT CHANCE OF RAIN ON TUESDAY AS MOIST FLOW WRAPS AROUND THE LOW AND INTO NORTHERN CALIFORNIA FROM THE SOUTH TO SOUTHEAST. THE MAIN VORT MAX IS HEADED FOR SOUTHERN CALIFORNIA...AND THE BEST INSTABILITY IS LIKELY TO STAY SOUTH OF THE CWA AS WELL. GFS IS STILL HINTING AT SOME SUBTROPICAL MOISTURE GETTING PULLED INTO THE FLOW AND HEADING NORTHWARD...BUT CERTAINLY NOT IN THE MANNER OF A CLASSIC PINEAPPLE CONNECTION. MODELS CONTINUE THE SLOWING TREND SO TRIMMED BACK POPS SLIGHTLY FOR THE MONDAY NIGHT PERIOD...AND ALLOWED CHANCE POPS TO INCREASE FROM THE SOUTH ON TUESDAY. SHOWERS WILL DECREASE FROM NORTHWEST TO SOUTHEAST LATE TUESDAY NIGHT INTO WEDNESDAY AS THE LOW MAKES LANDFALL SOUTH OF PT CONCEPTION...AND BEGINS TO MOVE INLAND TOWARD VEGAS AND THE 4 CORNERS STATES. THIS WILL ALLOW SOME ANTICYCLONIC ROTATION TO DEVELOP OVER THE PACIFIC NORTHEAST AND NORTHERN CALIFORNIA WEDNESDAY...AS ANOTHER STRONG LOW HEADS ACROSS THE GULF OF ALASKA. .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY...MODELS SHOW REASONABLE AGREEMENT IN HANDLING OF THE NEXT LOW FORECAST TO APPROACH THE PACIFIC NORTHWEST LATER THIS WEEK. TIMING HAS SLOWED SOMEWHAT TO FAVOR PRECIP AFFECTING MAINLY THE NORTHWEST PORTION OF THE CWA ON THURSDAY...SPREADING SOUTHWARD ON THURSDAY NIGHT....AND DECREASING TO THE NORTHEAST ON FRIDAY. FOR THE WEEKEND THE MODELS ALL INDICATE A LOW FORMING ON THE EAST SIDE OF A LONGWAVE RIDGE IN THE EASTERN PACIFIC. BY 12Z SATURDAY THE GFS AND EC ARE JOINED BY THE CANADIAN IN FORMING A CUTOFF LOW SOMEWHERE IN THE SOUTHERN CALIFORNIA/NORTHERN BAJA VICINITY...AS A STRONG RIDGE CONTINUES TO BUILD INTO THE PACIFIC NORTHWEST. BY SUNDAY THE GFS IS MOST AGGRESSIVE IN WESTWARD MOVEMENT OF THE CUTOFF...PUSHING IT OFFSHORE SOUTH OF 30 N. THIS TYPE OF SOLUTION FAVORS DRY WEATHER FOR NORTHWEST CALIFORNIA. CMC && .AVIATION...CURRENT OBSERVATIONS AND 10Z RUC ANALYSIS CONFIRM WEAK OFFSHORE FLOW OUT OF THE SOUTHEAST IS IN PLACE KEEPING FOG AND STRATUS FROM DEVELOPING ALONG THE COAST. THIS FLOW IS EXPECTED TO PERSIST THROUGH THE PERIOD KEEPING WIDESPREAD VFR FLYING CONDITIONS IN THE FORECAST. MID AND HIGH LEVEL CLOUD COVER WILL INCREASE TODAY AS A WEAKENING FRONTAL BOUNDARY APPROACHES THE AREA FROM THE NORTHWEST. BK .MARINE...A LOW PRESSURE SYSTEM HAS TAKEN SHAPE OFF THE COAST OF SOUTHERN CALIFORNIA THIS MORNING KEEPING SOUTHERLY WINDS IN PLACE OVER THE COASTAL WATERS OFF NORTHEN CALIFORNIA. THIS WILL PERSIST THROUGH TONIGHT WHEN THE WINDS WILL BEGIN TO SHIFT AROUND TO THE NORTHEAST IN RESPONSE TO SHORT LIVED HIGH PRESSURE THAT WILL BUILD IN NORTH OF THE AREA. A MIXED SWELL WILL MOVE INTO THE WATERS LATER THIS MORNING DUE TO THE LOW PRESSURE SOUTH OF THE AREA. THE DOMINANT SWELL WILL STILL BE OUT OF THE WEST AT 5 TO 6 FT...WITH A SOUTHERLY SWELL MOVING IN AT 3 FT. PERIODS WILL BE 11 SECONDS OUT OF THE WEST AND 6 TO 7 SECONDS OUT OF THE SOUTH. SOUTHERLY SWELL TRAIN WILL SUBSIDE TOMORROW EVENING AS THE NORTHWESTERLY SWELL BEGINS TO BUILD TO NEAR 12 FT ON WEDNESDAY NIGHT IN RESPONSE TO THE SHORT LIVED HIGH PRESSURE BUILDING INTO THE PAC NW. PERIODS WILL BE ON THE ORDER OF 15 SECONDS SO NOT EXPECTING A HAZARDOUS SEAS WARNING JUST AN ADVISORY FOR HAZARDOUS SEAS DURING THIS TIME. ANOTHER LARGER SWELL TRAIN WILL MOVE INTO THE WATERS FRIDAY MORNING. BK && .EKA WATCHES/WARNINGS/ADVISORIES... && $$ VISIT US AT HTTP://WWW.WEATHER.GOV/EUREKA ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 730 PM EST MON NOV 24 2008 .SYNOPSIS... A COMPLEX STORM SYSTEM WILL IMPACT THE REGION THROUGH TUESDAY EVENING. A LOW PRESSURE SYSTEM WILL APPROACH FROM THE GREAT LAKES REGION TONIGHT AND THEN DRIFT SLOWLY EAST ACROSS OUR REGION ON TUESDAY. THIS SYSTEM WILL BRING SNOW TO HIGHER ELEVATIONS WEST OF ALBANY...AND RAIN ACROSS MUCH OF THE HUDSON VALLEY EASTWARD TO WESTERN MASSACHUSETTS AND NORTHWEST CONNECTICUT. PRECIPITATION WILL TAPER OFF TUESDAY EVENING AS THE STORM SYSTEM PULLS AWAY. && .NEAR TERM /THROUGH TUESDAY NIGHT/... MONITORING TRENDS AND A RATHER IMPRESSIVE DIFFLUENCE EVOLVING ACROSS PA/NY WITH ASSOCIATED RADAR ECHOES FILLING RAPIDLY ACROSS THE EASTERN NY AND COOLING CLOUD TOPS. LAPS/RTMA DATA AND ASSOCIATED SURFACE OBS REVEAL TEMPERATURES HAVE RISEN IN THE HUDSON VALLEY FROM THE IMMEDIATE CAPITAL REGION SOUTHWARD THROUGH THE MID HUDSON VALLEY WITH MAINLY LOWER 40S. DEWPOINTS WERE BETWEEN 25F AND 35F AS WET BULB FREEZING TEMPERATURES WERE JUST NORTH OF THE CAPITAL REGION AND WEST. ACROSS PORTIONS OF THE MOHAWK VALLEY AND THE DACKS...MAINLY SNOW AS SEEN ON SEVERAL WEB CAMS AND REPORTING SURFACE OBS. BASED ON THOSE OBSERVATIONS AND THE LATEST RUC13 WET BULB ZERO HEIGHTS AND LOCALLY PRODUCED HIREF WRF...THINKING THE CURRENT HEADLINES LOOK GOOD AT THIS TIME. WE MIGHT BE A LITTLE HIGH WITH SNOW AMOUNTS ACROSS THE CATSKILLS AND WILL AWAIT FOR ADDITIONAL GROUND TRUTH BEFORE MAKING A SHIFT IN THE FORECAST. IT DOES SEEM THE HUDSON VALLEY LOCATIONS FROM THE IMMEDIATE CAPITAL REGION AND POINTS SOUTHWARD...A MAINLY RAIN EVENT MAY BE UNFOLDING. ADDITIONAL UPDATES WILL BE FORTHCOMING... PREVIOUS AFTERNOON DISCUSSION FOLLOWS... WINTER STORM WARNINGS HAVE BEEN ISSUED FOR THE WESTERN AND SOUTHERN ADIRONDACKS...AS WELL AS THE EASTERN CATSKILLS TONIGHT THROUGH TUESDAY FOR HEAVY SNOW. A FLOOD WATCH REMAINS IN PLACE FROM THE HUDSON VALLEY EASTWARD TO WESTERN NEW ENGLAND. PRECIPITATION WILL DEVELOP FROM SOUTHWEST TO NORTHEAST ACROSS THE AREA THIS EVENING AS ISENTROPIC LIFT ASSOC WITH A WARM FRONT INCREASES AHEAD OF A SURFACE CYCLONE SLOWLY DRIFTING EASTWARD ACROSS LAKE ERIE. HOWEVER...AS A POWERFUL CUT-OFF UPPER LEVEL LOW DIVES SOUTHEAST ACROSS THE GREAT LAKES TONIGHT INTO TUE...SECONDARY DEVELOPMENT WILL TAKE PLACE NEAR SOUTHEAST NY ALONG THE WARM FRONT...FOCUSING AN AXIS OF MODERATE TO HEAVY QPF ACROSS EASTERN NY INTO NEW ENGLAND. MODELS IN PRETTY GOOD AGREEMENT SHOWING QPF AMOUNTS OF 1-2" ACROSS THE AREA. HOWEVER...LOW LEVEL TEMP PROFILES AND ELEVATION WILL BE VERY CRITICAL IN DETERMINING RAIN VS SNOW AND RESULTANT WARNINGS/ADVISORIES. AT THIS TIME IT APPEARS TEMP WILL BE COLD ENOUGH FOR MAINLY SNOW ACROSS THE WESTERN AND SOUTHERN ADIRONDACKS...AS WELL AS THE FOR THE EASTERN CATSKILLS AND THE HIGHER ELEVATIONS OF SCHOHARIE COUNTY. THESE AREAS HAVE BEEN UPGRADED TO A WINTER STORM WARNING. THE AREA OF HIGHEST CONFIDENCE FOR WARNING LEVEL SNOW ARE ACROSS THE ADIRONDACKS. ONE COMPLICATING FACTOR ACROSS THE EASTERN CATSKILLS WILL BE THE ARRIVAL OF A WARM LAYER OF AIR ADVECTING IN AROUND 925 MB COURTESY OF A STRENGTHENING SOUTHERLY JET. HOWEVER...THE AIR ALOFT /AROUND 850 MB/ WILL REMAIN COOL AND COOL FURTHER DURING THE DAY TUE AS THE UPPER LOW MOVES EASTWARD ACROSS UPSTATE NY AND PA. SO THERE MAY BE A PERIOD OF RAIN MIXING IN BELOW 2000 FEET IN THE EASTERN CATSKILLS. THERE WILL LIKELY BE A SHARP DEMARCATION FOR RAIN/SNOW ACROSS THE FOOTHILLS OF THE ADIRONDACKS...MOHAWK VALLEY...UPPER HUDSON VALLEY...AND INTO THE SOUTHERN GREEN MOUNTAINS. LOW LEVEL AGEOSTROPHIC WIND COMPONENT WILL BE FAIRLY STRONG FROM THE N-NE WHICH WILL ALLOW COLD AIR TO REMAIN ENTRENCHED TONIGHT THROUGH MUCH OF TUE. THERE COULD BE WIDE RANGING SNOWFALL TOTALS IN THESE AREAS...SO WILL GO WITH WINTER WEATHER ADVISORIES. THERE MAY BE A BRIEF PERIOD OF SLEET/FREEZING RAIN DURING PRECIP TYPE TRANSITIONS...BUT IT APPEARS THE MAIN WINTER HAZARD ASSOC WITH HEADLINES WILL BE FROM SNOWFALL. LOW LEVEL FLOW WILL BECOME SOUTHEAST TUE MORNING ACROSS SOUTHERN VERMONT AND STRENGTHEN CONSIDERABLY. THIS WIND COMPONENT IS TYPICALLY FAVORABLE FOR STRONGER WINDS IN THE SOUTHERN GREEN MOUNTAINS. HOWEVER...THE STRONGEST WINDS ARE FORECAST TO BE JUST NORTH OF THE AREA. WILL NOT ISSUE ANY WIND ADVISORIES AT THIS TIME...BUT MAY BE NEEDED IN SUBSEQUENT SHIFTS. AREAS SOUTH AND EAST OF THE WINTER WEATHER ADVISORY AREA WILL EXPERIENCE PRIMARILY RAIN...WITH POSSIBLY SOME SNOW MIXED IN AT THE ONSET TONIGHT. FLOOD WATCHES REMAIN IN EFFECT...PLEASE SEE HYDRO SECTION FOR DETAILS. AT THE TAIL END OF THE STEADY PRECIP...THERE COULD BE ANOTHER CHANGEOVER TO SNOW AS COLD AIR WRAPS IN FROM THE SOUTH AND WEST WITH MINOR ACCUMULATIONS MAINLY TO THE NORTH AND EAST OF ALBANY AS THE SECONDARY LOW AND BOUNDARY LIFT NORTHWARD. A DRY SLOT WILL MOVE IN FROM THE SOUTH AND WEST TUE EVENING...CUTTING OFF THE PRECIP FOR THE ENTIRE AREA. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... ON WEDNESDAY...THE STACKED LOW WILL BE SITUATED OVER SOUTHEASTERN ONTARIO. CYCLONIC FLOW AROUND THE SYSTEM...ALONG WITH SOME LOCAL ENHANCEMENT OFF THE LAKES AND UPSLOPE TERRAIN EFFECTS...WILL ALLOW FOR THE CHC FOR SOME LIGHT SHOWERS. THE BOUNDARY LAYER TEMP PROFILE AND TIME OF DAY WILL ULTIMATELY DICTATE P-TYPE...WITH MAINLY SNOW SHOWERS IN WESTERN AREAS/HIGHER TERRAIN...AND MAINLY RAIN SHOWERS FOR THE HUDSON RIVER VALLEY. HAVE GENERALLY FOLLOWED CLOSE TO MAV GUIDANCE NUMBERS FOR TEMPS. ANY SNOW ACCUMULATION WILL BE LIMITED TO THE HIGHEST TERRAIN...AND WILL GENERALLY BE LESS THAN AN INCH. THE STORM WILL MOVE LITTLE ON WEDNESDAY NIGHT...WITH CYCLONIC SNOW SHOWERS/FLURRIES CONTINUING OVER MAINLY WESTERN/NORTHERN PARTS OF THE CWA. BOTH THE LATEST 18Z NAM AND 12Z GFS HINT AT THE SPOKE OF VORTICITY BRUSHING THROUGH THE ADIRONDACKS...SO COULD BE SOME ADDITIONAL LIGHT ACCUMULATION /AN INCH OR LESS/ ACROSS NORTHERN PARTS OF HAMILTON/HERKIMER COUNTIES. BEST LAKE ENHANCEMENT SHOULD BE NORTH OF THE AREA...AS SFC-850MB WINDS WILL GENERALLY BE A SW DIRECTION. MIN TEMPS WILL BE HELD UP DUE TO DECENT CLOUD COVER....SO ONLY AM EXPECTING 20S OVER THE MAJORITY OF THE AREA. BY THURSDAY...THE STORM WILL FINALLY BEGIN TO LIFT NORTHWARD INTO WESTERN QUEBEC /ACCORDING TO THE 12Z GFS/...AND SLOWLY WEAKEN. THIS SHOULD ALLOW FOR MUCH OF THE CYCLONIC SHOWERS TO BEGIN TO WANE BY THURSDAY EVENING. HOWEVER...STILL COULD HAVE SOME LAKE EFFECT TO DEAL WITH...AS THE FLOW BECOMES MORE WESTERLY. LAKE/AIR TEMP DIFFERENTIAL WILL NOT BE EXTREME /STABILITY CLASS LIKELY JUST CONDITIONAL/ BUT THERE COULD BE SOME LAKE EFFECT SNOW SHOWERS FOR PARTS OF THE WESTERN DACKS...ESP BY THURSDAY EVENING. THURSDAY/S MAX TEMPS SHOULD BE SIMILAR TO HIGHS ON WEDNESDAY...AS CLOUD COVER AND CYCLONIC FLOW SHOULD KEEPS TEMPS SLIGHTLY BELOW NORMAL ACROSS THE ENTIRE AREA. WITH A FEW MORE BREAKS IN THE CLOUDS BY THURSDAY NIGHT THANKS TO THE WEAKENING STORM...THURSDAY NIGHT/S MINS COULD BE A FEW DEGREES COOLER THAN WEDNESDAY NIGHT. && .LONG TERM /FRIDAY THROUGH MONDAY/... NOT A GREAT DEAL OF CERTAINTY REGARDING THE LONG TERM PERIOD...AS THE ECMWF AND GFS HAVE VARIED FROM RUN TO RUN REGARDING THE TIMING AND PLACEMENT OF SEVERAL FEATURES WHICH WILL HAVE A DIRECT IMPACT ON THE SENSIBLE WEATHER. BOTH OPERATIONAL 12Z RUNS OF THE MODELS DEPICT A STRONG SOUTHERLY STREAM JET OVER THE DEEP SOUTH /IN EXCESS OF 130 KTS/ AS WELL AS A WEAK CLIPPER MOVING THROUGH THE NORTHERN STREAM. THE MAIN DIFFERENCE BETWEEN THE MODELS IS THAT THE ECMWF IS ABOUT A DAY FASTER WITH THIS NORTHERN STREAM FEATURE. BOTH MODELS DO WANT TO PHASE THE UPPER LEVEL ENERGY...WITH BOTH MODELS DOING THIS OFFSHORE...ALBEIT THE GFS DOES THIS A LOT CLOSER TO THE COAST. WITH THE GFS SOLUTION...THE CWA...ALTHOUGH MAINLY ONLY EASTERN PARTS...WILL BE ON THE FAR WESTERN SIDE OF THIS STORM...AND COULD SEE SOME LIGHT RAIN/SNOW FOR FRIDAY NIGHT INTO SATURDAY MORNING...ALTHOUGH P-TYPE WILL ULTIMATELY DEPEND ON THE BOUNDARY LAYER TEMP PROFILE AND ELEVATION. MEANWHILE...IF THE ECMWF SOLUTION COMES TO FRUITION...THERE WILL BE NOTHING MORE THAN A BRIEF PERIOD OF RAIN/SNOW SHOWERS WITH THE CLIPPER FOR FRIDAY...AS ANY RAPIDLY DEVELOPING CYCLOGENESIS WILL OCCUR WELL TO THE EAST /SOUTH OF NOVA SCOTIA/. BOTH MODELS DO SHOW A COLDER PATTERN BEHIND THIS SYSTEM FOR LATER SATURDAY INTO MONDAY...WITH SLGT CHC/LOW CHC POPS WARRANTED FOR CYCLONIC INSTABILITY RAIN/SNOW SHOWERS...AND EVEN SOME LAKE EFFECT IN AREAS DOWNWIND OF LK ONTARIO. OVERALL...TEMPS LOOK TO RUN NEAR TO SOMEWHAT BELOW AVERAGE...ESP FOR LATE IN THE PERIOD...AS BOTH MODELS SHOW 850 MB TEMPS PLUNGING BETWEEN -6 TO -10 DEGREES C BY MONDAY AFTN. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... LATEST RETURNS FROM THE KENX WSR-88D SHOW PRECIP RAPIDLY MOVING TOWARDS THE REGION. AIR IS CURRENTLY FAIRLY DRY AT THE SURFACE...BUT WILL MOISTEN UP AS THE PRECIP FALLS THROUGH IT. AM EXPECTING PRECIP TO MOVE INTO THE TERMINALS BY 02Z-04Z. PRECIP SHOULD BEGIN ENTIRELY AS RAIN AT KPOU...AND MAY VERY BRIEFLY FALL AS A RAIN/SNOW MIX AT KALB. HOWEVER...COLDER AIR AT THE SURFACE WILL ALLOW FOR A FEW HOUR PERIOD OF SNOW AT KGFL...BEFORE IT CHANGES TO RAIN THERE ENTIRELY BY 07Z. ONCE THE PRECIP BEGINS...IT WILL LIKELY DROP VSBY TO THE MVFR RANGE. TOWARDS THE END OF THE NIGHT...STEADIER AND HEAVIER PRECIP WILL LIKELY DROP VSBY DOWN TO THE IFR RANGE...AND PERHAPS EVEN THE CIGS TOO...ESP AT KPOU. THIS SHOULD CONTINUE FOR MUCH OF THE MORNING AS THE UPPER LEVEL ENERGY FOR THE STORM APPROACHES THE REGION. THE STORM/S OCCLUDED FRONT AT THE SURFACE WILL BE MOVING THROUGH THE REGION BY EARLY TO MID AFTN TUESDAY...WHICH WILL CHANGE THE WINDS AROUND TO A MORE WESTERLY DIRECTION AND LIKELY SHUT OFF MOST OF THE PRECIP. THIS SHOULD ALLOW CIGS/VSBYS TO BOTH RECOVER BACK TO VFR RANGE BY LATE AFTN TUESDAY. THE OTHER AVIATION CONCERN IS FOR LLWS. AT THIS POINT...IT APPEARS TO BE ONLY A MARGINAL THREAT FOR A PORTION OF THE OVERNIGHT HOURS. WINDS AT THE 2000 FT LEVEL WILL BE AROUND 30-35 KTS...WHICH DEPENDING ON THE EXACT SURFACE WIND WILL DETERMINE IF THERE IS ENOUGH SHEAR TO MEET THE LLWS THRESHOLD. ANY LLWS SHOULD DIMINISH BY SUNRISE...AS THE BEST WINDS ALOFT SHIFT EASTWARD AWAY FROM THE REGION. OUTLOOK... WED...VFR/MVFR...CHC -SHRA/-SHSN. THU-FRI...VFR...NO SIG WX. SAT...VFR/MVFR...CHC -SHSN/-SHRA. && .HYDROLOGY... A FLOOD WATCH IS IN EFFECT FROM THE HUDSON RIVER VALLEY EASTWARD DUE TO FORECAST HIGH RAINFALL RATES ON FROZEN GROUND. A STRONG WINTER STORM WILL BRING SIGNIFICANT PRECIPITATION TO THE ALBANY HYDROLOGIC SERVICE AREA OVER NEXT 24 HOURS. MODEL TEMPERATURE PROFILES INDICATE THE MAJORITY OF THE PRECIPITATION WILL BE SNOW OVER THE HIGHER TERRAIN WEST OF THE HUDSON VALLEY...WITH PRIMARILY RAIN FROM THE HUDSON VALLEY EAST. 1 TO 2 INCHES OF LIQUID EQUIVALENT PRECIPITATION IS FORECAST FROM THE EVENT. HERE AT ALBANY...WE MEASURED THE GROUND FROZEN TO A DEPTH OF 3.5 INCHES THIS MORNING. DUE TO RECENT COLD WEATHER...IT IS ESTIMATED THAT THE GROUND IS FROZEN TO A DEPTH OF 3 TO 6 INCHES ACROSS THE HIGHER TERRAIN OF GREEN MOUNTAINS...BERKSHIRES...TACONICS AND LITCHFIELD HILLS. FORECAST HIGH RAINFALL RATES ON FROZEN GROUND TUESDAY MORNING WILL LIKELY LEAD TO SHARP RISES ON SMALL STREAMS AND CREEKS. SOME SMALL STREAMS MAY REACH FLOOD STAGE. FLOODING OF LARGER RIVERS IS LESS LIKELY...BUT MANY LARGER RIVERS INCLUDING THE METAWEE...THE BATTENKILL...THE WALLOOMSAC...THE HOOSIC AND THE HOUSATONIC MAY APPROACH FLOOD STAGE ON TUESDAY. FOR DETAILS ON THE RIVERS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...FLOOD WATCH FROM MIDNIGHT EST TONIGHT THROUGH TUESDAY EVENING FOR CTZ001-013. NY...WINTER STORM WARNING UNTIL MIDNIGHT EST TUESDAY NIGHT FOR NYZ032-033-042-047-058-063-082. FLOOD WATCH FROM MIDNIGHT EST TONIGHT THROUGH TUESDAY EVENING FOR NYZ041-043-049-050-052>054-059>061-064>066-083-084. WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TUESDAY NIGHT FOR NYZ038>041-043-048-051-083. MA...FLOOD WATCH FROM MIDNIGHT EST TONIGHT THROUGH TUESDAY EVENING FOR MAZ001-025. VT...FLOOD WATCH FROM MIDNIGHT EST TONIGHT THROUGH TUESDAY EVENING FOR VTZ013>015. WINTER WEATHER ADVISORY FROM 11 PM THIS EVENING TO MIDNIGHT EST TUESDAY NIGHT FOR VTZ013-014. && $$ SYNOPSIS...JPV NEAR TERM...BGM/JPV SHORT TERM...FRUGIS LONG TERM...FRUGIS AVIATION...FRUGIS HYDROLOGY...DIRIENZO WWW.WEATHER.GOV/ALBANY ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 329 PM EST MON NOV 24 2008 .SYNOPSIS... LOW PRESSURE WILL SPREAD PRECIPITATION INTO NEW ENGLAND TONIGHT AND TUESDAY...MOSTLY IN THE FORM OF RAIN WHICH WILL BE HEAVY AT TIMES. THE SYSTEM WILL ALSO BRING STRONG WINDS TO MUCH OF THE COASTAL PLAIN ON TUESDAY. COOLER AND MAINLY DRY WEATHER WILL RETURN WEDNESDAY THROUGH AT LEAST FRIDAY AFTERNOON...BEFORE ANOTHER SYSTEM MAY BRING SOME RAIN TO THE REGION LATE FRIDAY NIGHT AND SATURDAY. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 915 AND 1015 AM MINOR ADJUSTMENTS TO GRID TRENDS THIS MORNING. RUC 13 VIA TSECS HAS THE BEST HANDLE ON CURRENT AND NEAR TERM CLOUD BANDS NR 7000 FT. GRIDS MODIFIED. SURFACE HIGH PRESSURE WILL GRADUALLY MOVE OFF THE COAST TODAY AS LOW PRESSURE APPROACHES FROM THE WEST. THE RESULT WILL BE INCREASING HIGH CLOUDINESS...BUT ANY PRECIPITATION WILL HOLD OFF UNTIL THIS EVENING OR TONIGHT. IN FACT...WE MAY SEE A GOOD AMOUNT OF FILTERED SUNSHINE TODAY. TEMPERATURES WILL BE WARMER THAN THEY HAVE BEEN OVER THE LAST SEVERAL DAYS AS THE FLOW GOES SOUTH AND THE AIRMASS WARMS. EVEN STILL...HIGH TEMPS WILL TOP OUT AROUND 5 DEGREES BELOW NORMAL. MAXES WERE DERIVED FROM A BLEND OF NAM 2M TEMPS AND MAVMOSGUIDE...WITH SLIGHTLY MORE WEIGHT GIVEN TO THE MOS. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... 1110 AM... ISSUING HIGH WIND WATCH BOSTON TO MANCHESTER AND POINTS EAST TO CAPE ANN. SE WIND HIGH WIND CASES IN OUR CLIMO ARE RARE BUT MARGINAL HIGH WIND CASE ENVISIONED PER MODEL PRES CHANGES... LAPSE RATES...BL AND 925 MB WINDS BOTH 12Z GFS/NAM. NAM BL WINDS ARE UP TO 38 KTS NOW AT CONCORD. THAT SEEMS A LITTLE HIGH BUT PER COLLAB WITH GYX...ADDED ASH TO MHT. GREATEST CONFIDENCE IN SIGNIFICANT POWER OUTAGES AND SUSTAINED WIND 40 OR GREATER IS MQE AND BOS TO LWM REGION EWD. MAY SEE GUST 60 KTS AT MQE. WIND ADVY WILL BE ISSUED REMAINDER I95 REGION OF RI AND MASS AT 4PM. REMAINDER BLO FROM 4AM... CLOUDS WILL RAPIDLY INCREASE EARLY THIS EVENING AS LOW PRESSURE CONTINUES TO APPROACH. THE PRECIPITATION SHIELD WILL ARRIVE FROM WEST TO EAST...STARTING IN THE CT VALLEY SOMETIME BETWEEN 02Z AND 06Z...THEN SPREADING EASTWARD FROM THERE. THE DOMINANT PRECIPITATION TYPE WILL BE RAIN...ALTHOUGH A PORTION OF NW MASS AND SW NH MAY SEE A BRIEF PERIOD OF LIGHT SNOW AT THE START. NO ACCUMULATION IS EXPECTED. ATTM...THE THINKING IS THAT THE SFC TEMPS WILL WARM UP ENOUGH TO ALLOW FOR MUCH IN THE WAY OF FREEZING RAIN IF ANY AT ALL. IT WOULD BE EXTREMELY ISOLATED AT BEST. WENT WITH CATEGORICAL POPS FOR ALL ZONES BY LATE AT NIGHT. TEMPS WILL SLOWLY RISE OVERNIGHT AS THE LOW LEVEL JET GETS GOING. RAIN WILL BECOME HEAVY AT TIMES TUESDAY MORNING...ESPECIALLY THE WESTERN HALF OF THE CWA...BEFORE SHIFTING TO THE EASTERN HALF DURING THE AFTERNOON. CATEGORICAL POPS FOR ALL AREAS. BEST GUESS AT THIS TIME IS THAT A GENERAL .75 TO 1.5 INCHES OF RAIN WILL FALL...WITH LOCALLY HIGHER AMOUNTS. THIS SHOULDN/T CAUSE WIDESPREAD FLOODING PROBLEMS. HOWEVER...WE/LL LIKELY SEE THE NORMAL MINOR URBAN/POOR DRAINAGE FLOODING AT TIMES. WENT WITH A SLIGHT CHANCE OF THUNDER...MAINLY FOR SOUTHERN AND EASTERN ZONES...AS WEAK INSTABILITY MAY DEVELOP AS THE LLJ PUMPS NORTHWARD A DECENT PLUME OF THETA-E. THE BIGGEST CONCERN FOR TUESDAY MAY BE THE WINDS...AS A 65 KNOT SOUTHERLY LOW LEVEL JET DEVELOPS. THIS MAY LEAD TO SPEEDS OF WIND ADVISORY CRITERIA IF NOT ISOLD MARGINAL HWW CRITERIA TUESDAY AFTERNOON ALONG THE SOUTH COAST AND POSSIBLY THE REST OF EASTERN MASS. THE HIGHER TERRAIN MAY BE AFFECTED AS WELL. SUBSEQUENT SHIFTS MAY HAVE TO CONSIDER ADVISORIES/WATCHES/WARNINGS. ANY CONVECTION COULD BRING DOWN ISOLD STRONG WIND GUSTS AS WELL...ESPECIALLY IF SFC TEMPS REALLY WARM UP. THERE MAY BE A 1-2 FOOT SURGE ON THE SOUTH COAST BAYS WITH THE STRONG SOUTHERLY LLJ....BUT TIDES ARE LOW AND PRESSURE FALLS NOT OVERLY IMPRESSIVE. THEREFORE...NO COASTAL FLOODING PROBLEMS ARE EXPECTED AT THIS TIME. MODEL MAX TEMPS FOR TUESDAY LOOKED TOO LOW. THESE SOUTHERLY LLJ EVENTS ALMOST ALWAYS PRODUCE HIGHER SURFACE TEMPS THAN WHAT MOS AND EVEN MODEL 2M TEMPS INDICATE. WENT FOR MID 50S ACROSS EASTERN MASS/RI AND PORTIONS OF CT. COOLER TEMPS /40S - LOW 50S/ WILL BE FOUND ACROSS THE INTERIOR ALTHOUGH IT/S QUITE POSSIBLE THAT THEY WILL NEED TO BE RAISED AS WELL. OCCLUSION WILL BE MOVING ACROSS THE REGION EARLY TUE EVENING. NAM IS THE SLOWEST MOVING THE OCCLUSION THROUGH AND BRINGS A SLUG OF HEAVY RAIN TO E MA INTO SE NH AT THE NOSE OF A PERSISTENT SELY LLJ. CONSENSUS AMONG OTHER MODELS INCLUDING GFS FAVORS A FASTER SOLUTION SO WE LEANED TOWARD GFS WHICH LIFTS THE HEAVIER RAFL NORTH AND EAST OF SNE BY TUE EVENING. HOWEVER...SOME RAIN WILL LIKELY LINGER ACROSS NE ZONES NEAR THE NOSE OF THE LLJ SO WE WILL HAVE LIKELY TO CATEGORICAL POPS TUE EVENING FROM SW NH THROUGH E MA WITH LOWER POPS FURTHER SW AS DRY SLOT MOVES IN. ALSO...GFS INSTABILITY PARAMETERS SUGGEST ISOLD ELEVATED THUNDER POSSIBLE E MA THROUGH SE NH. TREND TUE NIGHT WILL BE FOR DECREASING POPS AS THE DRY SLOT MOVES THROUGH. WIND MAY STILL BE A CONCERN TUE EVENING FROM CAPE COD THROUGH CAPE ANN WHICH WILL BE CLOSEST TO THE LLJ AND WILL HAVE HIGHER GUSTS IN THIS REGION. COLDER AIR WILL BE SLOW TO MOVE IN TUE NIGHT AS UPPER LOW REMAINS TO THE NW WITH SOUTHERLY FLOW ALOFT. MIN TEMPS WILL RANGE FROM UPPER 20S FAR NW TO MID/UPPER 30S COASTAL PLAIN. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... WEDNESDAY... THE DRY SLOT WILL HAVE WRAPPED INTO SOUTHERN NEW ENGLAND BY EARLY WEDNESDAY MORNING. WE EXPECT PARTLY SUNNY SKIES IN THE MORNING...BUT STEEP LAPSE RATES WITH THE COLD AIR ALOFT SHOULD RESULT IN LOTS OF DIURNAL CUMULUS DEVELOPING BY AFTERNOON AND GENERALLY MOSTLY CLOUDY SKIES. THE UPPER LEVEL LOW LOOKS TO REMAIN WELL TO OUR NORTHWEST...SO WE EXPECT MAINLY A DRY DAY. HOWEVER...WILL MAINTAIN A SLIGHT CHANCE POP FOR A BRIEF PASSING SHOWER/SPRINKLE IN THE AFTERNOON. IT COULD BE IN THE FORM OF A WET SNOW SHOWER/FLURRY IN THE HIGHEST TERRAIN...BUT NO ACCUMULATION EXPECTED WITH TEMPERATURES ABOVE FREEZING. HIGH TEMPERATURES SHOULD MAINLY BE IN THE MID TO UPPER 40S...WITH READINGS A BIT COOLER IN THE HIGHER TERRAIN. WEDNESDAY NIGHT... AN ISOLATED SHOWER/SPRINKLE WILL STILL BE POSSIBLE IN THE EARLY EVENING...BUT OTHERWISE PARTLY TO MOSTLY CLOUDY SKIES FOR MUCH OF THE NIGHT. THEREFORE...WE LEANED TOWARDS THE WARMER MET GUIDANCE WITH A FAIR AMOUNT OF CLOUDS EXPECTED OVERNIGHT. LOWS SHOULD MAINLY BE IN THE UPPER 20S AND LOWER 30S ALTHOUGH IT WILL BE A BIT WARMER IN THE URBAN HEAT ISLAND OF BOSTON. THURSDAY... SHOULD SEE PARTIAL SUNSHINE...BUT ANOTHER DAY OF DIURNAL AFTERNOON CUMULUS EXPECTED...PARTICULARLY ACROSS THE INTERIOR WITH A POCKET OF COLD AIR ALOFT. WILL INCLUDE A SLIGHT CHANCE POP FOR PERHAPS A BRIEF INSTABILITY PASSING RAIN/SNOW SHOWER ACROSS THE DISTANT INTERIOR...BUT CAN NOT SEE MUCH MORE THAN THAT. HIGHS WILL MAINLY BE IN THE 40S. FRIDAY AND SATURDAY... CLOUDS SHOULD INCREASE DURING THE DAY FRIDAY OUT AHEAD OF THE NEXT LOW PRESSURE SYSTEM. THE GFS/CANADIAN HAVE PRECIPITATION OVER SPREADING MOST OF THE REGION LATE FRIDAY NIGHT...WHILE THE GFS ENSEMBLES ARE A BIT SLOWER AND HAVE THE BULK OF THE ACTION SATURDAY AND SATURDAY NIGHT. THIS FAR OUT THERE IS PLENTY OF UNCERTAINTY ON THE TIMING SO WILL CARRY CHANCE POPS FRIDAY NIGHT THROUGH SATURDAY NIGHT. BASED ON THE EXPECTED TRACK OF THE SYSTEM...WE EXPECT MAINLY RAIN FROM THIS SYSTEM. HOWEVER...CAN NOT RULE OUT A BRIEF PERIOD OF SNOW OR ICE ACROSS THE DISTANT INTERIOR AT THE ONSET. THE ECMWF SEEMS TO BE A BIT OF AN OUTLIER DEVELOPING THE WAVE FURTHER EAST AND HAS LITTLE IF ANY PRECIPITATION FROM THIS SYSTEM. WHILE WE DO NOT EXPECT A LOT OF PRECIPITATION WITH THIS SYSTEM...WOULD FAVOR MOST OF THE REGION SEEING AT LEAST SOME RAIN. SUNDAY AND MONDAY... BASED ON THE LATEST MODELS DRY AND CHILLY WEATHER WILL WORK BACK INTO THE REGION ON SUNDAY. THE GFS IS DRY ON MONDAY AND MONDAY NIGHT BUT ITS ENSEMBLES AND THE 12Z ECMWF INDICATE THE THREAT OF MORE PRECIPITATION SOMETIME MONDAY OR MONDAY NIGHT. LOW CONFIDENCE THIS FAR OUT...BUT THIS SYSTEM MAY BRING SOME WINTRY WEATHER TO PORTIONS OF OUR REGION WITH A CHILLY AIRMASS IN PLACE. THEREFORE...WILL CARRY SOME CHANCE POPS MONDAY AND MONDAY NIGHT BUT AGAIN THERE IS LOW CONFIDENCE THIS FAR OUT. && .AVIATION /21Z MONDAY THROUGH SATURDAY/... TODAY...VFR OCNL CIGS NEAR 8000 FT ALONG WITH RELATIVELY LIGHT SOUTHERLY WINDS. TONIGHT...ADVANCING LOW PRESSURE WILL BRING GRADUALLY LOWERING CEILINGS...FOLLOWED BY RAIN SPREADING ACROSS SOUTHERN NEW ENGLAND FROM WEST TO EAST LATER THIS EVENING. THE NIGHT WILL START WITH VFR CONDITIONS...BUT THEN DETERIORATE TO MVFR...THEN IFR/LIFR LATE. TUESDAY...IFR TO LIFR CONDITIONS EXPECTED IN RAIN...POSSIBLY HEAVY AT TIMES. LLWS IS LIKELY...ESPECIALLY AT TERMINALS IN RI AND EASTERN MASS AS SOUTHEASTERLY LLJ DEVELOPS. ISOLD TSRA POSSIBLE. ESE SFC WINDS LIKELY GUST 40 KT RI/EASTERN MASS...ESPECIALLY BOSTON AREA 15Z-21Z. LLWS EXPECTED FROM PVD TO MHT AND EAST. LINGERING MVFR/IFR IN RAIN TUE EVENING ESPECIALLY MHT-BOS-HYA- ACK...IMPROVING TO VFR OVERNIGHT. RAPIDLY DIMINISHING WINDS EXPECTED. OUTLOOK...WEDNESDAY THROUGH SATURDAY... WEDNESDAY THROUGH FRIDAY...MAINLY VFR. FRIDAY NIGHT THROUGH SATURDAY NIGHT...WE WILL PROBABLY SEE A PERIOD OF MVFR/IFR CONDITIONS IN SOME RAIN SHOWERS OVER THIS PERIOD. TIMING REMAINS UNCERTAIN THROUGH. && .MARINE... QUIET DAY TODAY ON THE LOCAL WATERS WITH SUB-SCA CONDITIONS EXPECTED. RELATIVELY LIGHT SOUTHERLY FLOW EXPECTED. LOW PRESSURE APPROACHES TONIGHT. SOUTHERLY FLOW WILL STRENGTHEN MARKEDLY AFTER MIDNIGHT. WENT WITH A GALE WARNING FOR ALL WATERS STARTING AT 06Z TO KEEP THINGS SIMPLE...ALTHOUGH GALES MAY NOT ARRIVE ON NORTHERN WATERS TIL A BIT LATER ON. SOUTHERLY FLOW INCREASES EVEN MORE DURING THE DAY ON TUESDAY. AFTER LOOKING OVER ALL THE AVAILABLE DATA...DECIDED TO GO WITH STRONG GALES ON ALL WATERS INSTEAD OF STORMS. HAVE ALLOWED GUST NR 50 KTS MERR RVR TO NEAR BOSTON HARBOR WATERS TUE AFTN. LOW LEVEL INVERSION CAN INHIBIT BUT PRES GRAD AND TURB MXG MAY ALLOW FOR GST 50KTS....ESP MERR RIVER REGION. HOWEVER...IT/S POSSIBLE THAT WINDS COULD BE SLIGHTLY STRONGER LATER TUESDAY...RESULTING IN A BRIEF PERIOD OF MARGINAL STORM FORCE WINDS. SEAS ON THE OUTER WATERS BUILD UP TO 15 FEET...WOULDN/T BE SURPRISED TO SEE 44008 AND 44018 TOP OUT BETWEEN 15 AND 20 FEET. STRONGEST WINDS BY TUE EVENING WILL BE ACROSS EASTERN WATERS EAST OF CAPE ANN TO CAPE COD WHERE STRONG SE GALES LIKELY INVOF LLJ. GUSTS TO 45 KT POSSIBLE. WINDS WILL SHIFT TO SW AND DECREASE AS OCCLUSION MOVES THROUGH. THIS WILL HAPPEN BY TUE EVENING OVER THE WESTERN WATERS AND AROUND MIDNIGHT EASTERN WATERS. SEAS UP TO 15 FEET OUTER EASTERN WATERS TUE NIGHT. OUTLOOK...WEDNESDAY THROUGH SATURDAY... WEDNESDAY THROUGH FRIDAY...WINDS WILL GENERALLY REMAIN BELOW SCA THRESHOLDS OVER THIS TIME. HOWEVER...ROUGH SEAS OVER THE OUTER-WATERS WILL CONTINUE REQUIRING SCA FOR MUCH IF NOT THE ENTIRE PERIOD. FRIDAY NIGHT AND SATURDAY...WE MAY SEE A BRIEF PERIOD OF SCA WIND GUSTS IN ASSOCIATION WITH OUR NEXT SYSTEM. OTHERWISE...HEADLINES WILL LIKELY NEED TO REMAIN UP FOR THE OUTER-WATERS MOST OF THE TIME. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...WIND ADVISORY FROM 7 AM TO 6 PM EST TUESDAY FOR MAZ013-017>024. HIGH WIND WATCH FROM TUESDAY MORNING THROUGH TUESDAY AFTERNOON FOR MAZ005>007-014>016. NH...HIGH WIND WATCH FROM TUESDAY MORNING THROUGH TUESDAY AFTERNOON FOR NHZ012. RI...WIND ADVISORY FROM 7 AM TO 6 PM EST TUESDAY FOR RIZ002-004>008. MARINE...GALE WARNING FROM 4 AM TO 7 PM EST TUESDAY FOR ANZ230>237-254- 255. STORM WARNING FROM 11 AM TO 7 PM EST TUESDAY FOR ANZ250. && $$ SYNOPSIS...DRAG/FRANK NEAR TERM...DRAG/EKSTER SHORT TERM...DRAG/EKSTER LONG TERM...FRANK AVIATION...NMB/FRANK MARINE...DRAG/FRANK ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 138 PM EST MON NOV 24 2008 .SYNOPSIS... LOW PRESSURE IN THE GREAT LAKES TODAY WILL SPREAD PRECIPITATION INTO NEW ENGLAND TONIGHT AND TUESDAY...MOSTLY IN THE FORM OF RAIN. THE SYSTEM MAY BRING STRONG WINDS AS WELL...ESPECIALLY NEAR THE COAST. COOLER AND DRY WEATHER WILL RETURN IN THE WAKE OF THE LOW MIDWEEK ON. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... 915 AND 1015 AM MINOR ADJUSTMENTS TO GRID TRENDS THIS MORNING. RUC 13 VIA TSECS HAS THE BEST HANDLE ON CURRENT AND NEAR TERM CLOUD BANDS NR 7000 FT. GRIDS MODIFIED. SURFACE HIGH PRESSURE WILL GRADUALLY MOVE OFF THE COAST TODAY AS LOW PRESSURE APPROACHES FROM THE WEST. THE RESULT WILL BE INCREASING HIGH CLOUDINESS...BUT ANY PRECIPITATION WILL HOLD OFF UNTIL THIS EVENING OR TONIGHT. IN FACT...WE MAY SEE A GOOD AMOUNT OF FILTERED SUNSHINE TODAY. TEMPERATURES WILL BE WARMER THAN THEY HAVE BEEN OVER THE LAST SEVERAL DAYS AS THE FLOW GOES SOUTH AND THE AIRMASS WARMS. EVEN STILL...HIGH TEMPS WILL TOP OUT AROUND 5 DEGREES BELOW NORMAL. MAXES WERE DERIVED FROM A BLEND OF NAM 2M TEMPS AND MAVMOSGUIDE...WITH SLIGHTLY MORE WEIGHT GIVEN TO THE MOS. && .SHORT TERM /8 PM THIS EVENING THROUGH TUESDAY NIGHT/... 1110 AM... ISSUING HIGH WIND WATCH BOSTON TO MANCHESTER AND POINTS EAST TO CAPE ANN. SE WIND HIGH WIND CASES IN OUR CLIMO ARE RARE BUT MARGINAL HIGH WIND CASE ENVISIONED PER MODEL PRES CHANGES... LAPSE RATES...BL AND 925 MB WINDS BOTH 12Z GFS/NAM. NAM BL WINDS ARE UP TO 38 KTS NOW AT CONCORD. THAT SEEMS A LITTLE HIGH BUT PER COLLAB WITH GYX...ADDED ASH TO MHT. GREATEST CONFIDENCE IN SIGNIFICANT POWER OUTAGES AND SUSTAINED WIND 40 OR GREATER IS MQE AND BOS TO LWM REGION EWD. MAY SEE GUST 60 KTS AT MQE. WIND ADVY WILL BE ISSUED REMAINDER I95 REGION OF RI AND MASS AT 4PM. REMAINDER BLO FROM 4AM... CLOUDS WILL RAPIDLY INCREASE EARLY THIS EVENING AS LOW PRESSURE CONTINUES TO APPROACH. THE PRECIPITATION SHIELD WILL ARRIVE FROM WEST TO EAST...STARTING IN THE CT VALLEY SOMETIME BETWEEN 02Z AND 06Z...THEN SPREADING EASTWARD FROM THERE. THE DOMINANT PRECIPITATION TYPE WILL BE RAIN...ALTHOUGH A PORTION OF NW MASS AND SW NH MAY SEE A BRIEF PERIOD OF LIGHT SNOW AT THE START. NO ACCUMULATION IS EXPECTED. ATTM...THE THINKING IS THAT THE SFC TEMPS WILL WARM UP ENOUGH TO ALLOW FOR MUCH IN THE WAY OF FREEZING RAIN IF ANY AT ALL. IT WOULD BE EXTREMELY ISOLATED AT BEST. WENT WITH CATEGORICAL POPS FOR ALL ZONES BY LATE AT NIGHT. TEMPS WILL SLOWLY RISE OVERNIGHT AS THE LOW LEVEL JET GETS GOING. RAIN WILL BECOME HEAVY AT TIMES TUESDAY MORNING...ESPECIALLY THE WESTERN HALF OF THE CWA...BEFORE SHIFTING TO THE EASTERN HALF DURING THE AFTERNOON. CATEGORICAL POPS FOR ALL AREAS. BEST GUESS AT THIS TIME IS THAT A GENERAL .75 TO 1.5 INCHES OF RAIN WILL FALL...WITH LOCALLY HIGHER AMOUNTS. THIS SHOULDN/T CAUSE WIDESPREAD FLOODING PROBLEMS. HOWEVER...WE/LL LIKELY SEE THE NORMAL MINOR URBAN/POOR DRAINAGE FLOODING AT TIMES. WENT WITH A SLIGHT CHANCE OF THUNDER...MAINLY FOR SOUTHERN AND EASTERN ZONES...AS WEAK INSTABILITY MAY DEVELOP AS THE LLJ PUMPS NORTHWARD A DECENT PLUME OF THETA-E. THE BIGGEST CONCERN FOR TUESDAY MAY BE THE WINDS...AS A 65 KNOT SOUTHERLY LOW LEVEL JET DEVELOPS. THIS MAY LEAD TO SPEEDS OF WIND ADVISORY CRITERIA IF NOT ISOLD MARGINAL HWW CRITERIA TUESDAY AFTERNOON ALONG THE SOUTH COAST AND POSSIBLY THE REST OF EASTERN MASS. THE HIGHER TERRAIN MAY BE AFFECTED AS WELL. SUBSEQUENT SHIFTS MAY HAVE TO CONSIDER ADVISORIES/WATCHES/WARNINGS. ANY CONVECTION COULD BRING DOWN ISOLD STRONG WIND GUSTS AS WELL...ESPECIALLY IF SFC TEMPS REALLY WARM UP. THERE MAY BE A 1-2 FOOT SURGE ON THE SOUTH COAST BAYS WITH THE STRONG SOUTHERLY LLJ....BUT TIDES ARE LOW AND PRESSURE FALLS NOT OVERLY IMPRESSIVE. THEREFORE...NO COASTAL FLOODING PROBLEMS ARE EXPECTED AT THIS TIME. MODEL MAX TEMPS FOR TUESDAY LOOKED TOO LOW. THESE SOUTHERLY LLJ EVENTS ALMOST ALWAYS PRODUCE HIGHER SURFACE TEMPS THAN WHAT MOS AND EVEN MODEL 2M TEMPS INDICATE. WENT FOR MID 50S ACROSS EASTERN MASS/RI AND PORTIONS OF CT. COOLER TEMPS /40S - LOW 50S/ WILL BE FOUND ACROSS THE INTERIOR ALTHOUGH IT/S QUITE POSSIBLE THAT THEY WILL NEED TO BE RAISED AS WELL. OCCLUSION WILL BE MOVING ACROSS THE REGION EARLY TUE EVENING. NAM IS THE SLOWEST MOVING THE OCCLUSION THROUGH AND BRINGS A SLUG OF HEAVY RAIN TO E MA INTO SE NH AT THE NOSE OF A PERSISTENT SELY LLJ. CONSENSUS AMONG OTHER MODELS INCLUDING GFS FAVORS A FASTER SOLUTION SO WE LEANED TOWARD GFS WHICH LIFTS THE HEAVIER RAFL NORTH AND EAST OF SNE BY TUE EVENING. HOWEVER...SOME RAIN WILL LIKELY LINGER ACROSS NE ZONES NEAR THE NOSE OF THE LLJ SO WE WILL HAVE LIKELY TO CATEGORICAL POPS TUE EVENING FROM SW NH THROUGH E MA WITH LOWER POPS FURTHER SW AS DRY SLOT MOVES IN. ALSO...GFS INSTABILITY PARAMETERS SUGGEST ISOLD ELEVATED THUNDER POSSIBLE E MA THROUGH SE NH. TREND TUE NIGHT WILL BE FOR DECREASING POPS AS THE DRY SLOT MOVES THROUGH. WIND MAY STILL BE A CONCERN TUE EVENING FROM CAPE COD THROUGH CAPE ANN WHICH WILL BE CLOSEST TO THE LLJ AND WILL HAVE HIGHER GUSTS IN THIS REGION. COLDER AIR WILL BE SLOW TO MOVE IN TUE NIGHT AS UPPER LOW REMAINS TO THE NW WITH SOUTHERLY FLOW ALOFT. MIN TEMPS WILL RANGE FROM UPPER 20S FAR NW TO MID/UPPER 30S COASTAL PLAIN. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... CLOSED LOW LIFTS NWD INTO CANADA WED. MAY GET ENOUGH DRYING FOR SOME SUNSHINE WED MORNING BUT CLOUDS SHOULD QUICKLY FILL BACK IN ESPECIALLY IN THE INTERIOR. CANT RULE OUT A FEW RA/SNW SHOWERS AS SHORTWAVE ENERGY ROTATES AROUND THE UPPER LOW. BEST CHC WILL BE ACROSS NW ZONES CLOSEST TO THE COLD POOL ALOFT. SEASONABLE TEMPS EXPECTED WED. THERE ARE MODEL DIFFERENCES IN THE HANDLING OF CLOSED LOW TOWARD THE END OF THE WEEK. ECMWF NOW MOVES CLOSED LOW BACK SWD ACROSS NEW ENG BUT THIS IS THE OUTLIER AS GFS/UKMET/GGEM KEEP LOW WELL TO THE NORTH WITH WEAK HIGH PRESSURE BUILDING IN BY FRI. FOLLOWED CONSENSUS AND WILL HAVE DRY FCST FOR THU/FRI WITH SEASONABLE TEMPS. UPPER VORTEX SETS UP NEAR JAMES BAY FOR THE WEEKEND WITH LONG WAVE TROF ACROSS GT LAKES BUT THERE IS CONSIDERABLE MODEL SPREAD IN THE HANDLING OF SHORTWAVES ROTATING THROUGH. ECMWF/GFS HAVE A STORM FOR THE WEEKEND BUT IT LOOKS TO BE MOSTLY WET. WE WILL HAVE CHC POPS FOR SAT/SUN ALTHOUGH ECMWF DRIES IT OUT FOR SUN. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... TODAY...VFR OCNL CIGS NEAR 8000 FT ALONG WITH RELATIVELY LIGHT SOUTHERLY WINDS. TONIGHT...ADVANCING LOW PRESSURE WILL BRING GRADUALLY LOWERING CEILINGS...FOLLOWED BY RAIN SPREADING ACROSS SOUTHERN NEW ENGLAND FROM WEST TO EAST LATER THIS EVENING. THE NIGHT WILL START WITH VFR CONDITIONS...BUT THEN DETERIORATE TO MVFR...THEN IFR/LIFR LATE. TUESDAY...IFR TO LIFR CONDITIONS EXPECTED IN RAIN...POSSIBLY HEAVY AT TIMES. LLWS IS LIKELY...ESPECIALLY AT TERMINALS IN RI AND EASTERN MASS AS SOUTHEASTERLY LLJ DEVELOPS. ISOLD TSRA POSSIBLE. ESE SFC WINDS LIKELY GUST 40 KT RI/EASTERN MASS...ESPECIALLY BOSTON AREA 15Z-21Z. LLWS EXPECTED FROM PVD TO MHT AND EAST. LINGERING MVFR/IFR IN RAIN TUE EVENING ESPECIALLY MHT-BOS-HYA- ACK...IMPROVING TO VFR OVERNIGHT. RAPIDLY DIMINISHING WINDS EXPECTED. OUTLOOK...WED THROUGH FRIDAY... MAINLY VFR WED THROUGH FRI. && .MARINE... QUIET DAY TODAY ON THE LOCAL WATERS WITH SUB-SCA CONDITIONS EXPECTED. RELATIVELY LIGHT SOUTHERLY FLOW EXPECTED. LOW PRESSURE APPROACHES TONIGHT. SOUTHERLY FLOW WILL STRENGTHEN MARKEDLY AFTER MIDNIGHT. WENT WITH A GALE WARNING FOR ALL WATERS STARTING AT 06Z TO KEEP THINGS SIMPLE...ALTHOUGH GALES MAY NOT ARRIVE ON NORTHERN WATERS TIL A BIT LATER ON. SOUTHERLY FLOW INCREASES EVEN MORE DURING THE DAY ON TUESDAY. AFTER LOOKING OVER ALL THE AVAILABLE DATA...DECIDED TO GO WITH STRONG GALES ON ALL WATERS INSTEAD OF STORMS. HAVE ALLOWED GUST NR 50 KTS MERR RVR TO NEAR BOSTON HARBOR WATERS TUE AFTN. LOW LEVEL INVERSION CAN INHIBIT BUT PRES GRAD AND TURB MXG MAY ALLOW FOR GST 50KTS....ESP MERR RIVER REGION. HOWEVER...IT/S POSSIBLE THAT WINDS COULD BE SLIGHTLY STRONGER LATER TUESDAY...RESULTING IN A BRIEF PERIOD OF MARGINAL STORM FORCE WINDS. SEAS ON THE OUTER WATERS BUILD UP TO 15 FEET...WOULDN/T BE SURPRISED TO SEE 44008 AND 44018 TOP OUT BETWEEN 15 AND 20 FEET. STRONGEST WINDS BY TUE EVENING WILL BE ACROSS EASTERN WATERS EAST OF CAPE ANN TO CAPE COD WHERE STRONG SE GALES LIKELY INVOF LLJ. GUSTS TO 45 KT POSSIBLE. WINDS WILL SHIFT TO SW AND DECREASE AS OCCLUSION MOVES THROUGH. THIS WILL HAPPEN BY TUE EVENING OVER THE WESTERN WATERS AND AROUND MIDNIGHT EASTERN WATERS. SEAS UP TO 15 FEET OUTER EASTERN WATERS TUE NIGHT. OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY... WINDS WILL BE MAINLY BELOW SCA LEVELS WED THROUGH FRI...MOSTLY FROM A WESTERLY DIRECTION. A PERIOD OF EASTERLY WINDS EXPECTED WED OVER THE EASTERN WATERS. HIGH SEAS WILL PERSIST OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...HIGH WIND WATCH FROM TUESDAY MORNING THROUGH TUESDAY AFTERNOON FOR MAZ005>007-014>016. NH...HIGH WIND WATCH FROM TUESDAY MORNING THROUGH TUESDAY AFTERNOON FOR NHZ012. RI...NONE. MARINE...GALE WARNING FROM 1 AM TO 6 PM EST TUESDAY FOR ANZ230>237-250- 254-255. && $$ SYNOPSIS...DRAG/EKSTER NEAR TERM...DRAG/EKSTER SHORT TERM...DRAG/EKSTER LONG TERM...KJC AVIATION...KJC/NMB MARINE...KJC/DRAG/EKSTER ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 1258 AM EST MON NOV 24 2008 .SYNOPSIS... ARCTIC HIGH PRESSURE WILL SLOWLY DRIFT OFFSHORE ALLOWING OUR UNSEASONABLY COLD AIR MASS TO MODERATE. LOW PRESSURE WILL DEVELOP TO OUR WEST ON MONDAY...AND THEN REFORM OVER OUR REGION BY TUESDAY. THIS SYSTEM WILL BRING A WINTRY MIX WHICH COULD IMPACT THANKSGIVING TRAVEL. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 830 PM EST...MID LEVEL CLOUDS ARE QUICKLY OVERSPREADING THE REGION FROM THE W...IN RESPONSE TO WEAKENING SHORTWAVE PASSING THROUGH...AS WELL AS INTENSIFYING MID LEVEL WARM ADVECTION/ISENTROPIC LIFT. THE RUC13 DEPICTS THIS MOISTURE RATHER WELL...ESP AROUND 700 MB...AND ALSO INDICATES THAT THE ASSOCIATED CLOUDS SHOULD GRADUALLY SHIFT TO THE N/E WELL AFTER MIDNIGHT. THUS...WE HAVE INCREASED THE CLOUD COVER THROUGH THE EARLY MORNING HOURS...AND ALSO HAVE SLOWED THE TEMP FALL OVERNIGHT...AS TEMPS SHOULD HOLD NEARLY OVER THE NEXT SEVERAL HOURS AS THE THICKEST MID LEVEL CLOUDS PASS THROUGH. THE TEMPS SHOULD ACCELERATE DOWNWARD ONCE AGAIN JUST PRIOR TO DAYBREAK...AS SOME BREAKS DEVELOP...ESP FROM ALBANY SOUTH AND WEST. THEREFORE...WE HAVE NOT CHANGED THE EXPECTED MIN TEMPS MUCH...JUST THE TEMP CURVE FOR THE OVERNIGHT PERIOD. OTHERWISE...SOME VERY LIGHT SNOW/FLURRIES ARE STILL POSSIBLE ACROSS EXTREME NORTHERN HERKIMER/NW HAMILTON COS OVER THE NEXT FEW HOURS...AS LATEST KTYX RADAR CONTINUES TO SHOW SOME WEAK REFLECTIVITIES BRUSHING THIS REGION. HOWEVER...AS LOW LEVEL FLOW CONTINUES TO BACK...AND MID LEVEL FORCING DIMINISHES...SO SHOULD THREAT OF ANY SNOW SHOWERS AFTER MIDNIGHT. && .SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY/... UPPER SYSTEM DROPPING OUT OF CANADA AND THROUGH THE GREAT LAKES WILL STRENGTHEN THE SOUTHWESTERLY BOUNDARY LAYER WINDS AND WARM ADVECTION...SO EVEN WITH INCREASING HIGH AND MID CLOUDS THROUGH THE DAY...TEMPERATURES SHOULD REACH WELL INTO THE 30S TO MID 40S FOR HIGHS. MONDAY NIGHT...ISENTROPIC LIFT INCREASES AND FRONTOGENETIC FORCING INCREASES SUPPORTING PRECIPITATION SPREADING ACROSS THE REGION. GENERAL CONSENSUS FROM MOST SOURCES OF GUIDANCE/ENSEMBLES SUGGEST AREAS WEST OF THE HUDSON VALLEY COULD SEE MOSTLY SNOW MONDAY NIGHT...WHILE AREAS ALONG AND EAST OF THE HUDSON VALLEY COULD SEE A BRIEF PERIOD OF SNOW/MIX BEFORE CHANGING TO A COLD RAIN AFTER MIDNIGHT. WITH THE RAPID WARMING ALOFT...SOME AREAS COULD SEE A BRIEF PERIOD OF FREEZING RAIN AROUND SUNRISE...BEFORE SURFACE TEMPERATURES CAN RESPOND TO THE WARM ADVECTION LATER IN THE MORNING. HIGHER ELEVATIONS OF THE GREENS AND BERKSHIRES COULD SEE A DECENT PERIOD OF SNOW MONDAY NIGHT AS WELL. LOWS MONDAY NIGHT WILL BE IN THE 20S TO MID 30S...AND MAY OCCUR DURING THE EVENING WHEN PRECIPITATION BEGINS AND TEMPERATURES FALL A BIT TOWARD WET BULBS...THEN COULD RISE A COUPLE/FEW DEGREES TOWARD SUNRISE. ........... ADDED AT 434 PM... TEXT FORECAST FOR MONDAY NIGHT AND TUESDAY NORNING WILL INDICATE QUITE THE MIX AND TRANSITION OF PRECIPITATION TYPES IN SOME AREAS...BUT VARIOUS PRECIPITATION TYPES SHOULD BE OBSERVED AT DIFFERENT ELEVATION LEVELS...AND BE CHANGABLE THROUGH THE NIGHT AND MORNING. COLD GROUND COULD CONTRIBUTE TO OBSERVATIONS OF FREEZING RAIN AS WELL. SUGGESTING 2-4" OF SNOW IN SOME OF THE ADIRONDACKS THROUGH MONDAY NIGHT...AND 3-6" IN OTHER PARTS OF THE ADIRONDACKS...JUST AS A STARTING POINT...AS AMOUNTS WILL CERTAINLY NEED TO BE ADJUSTED ONE WAY OR ANOTHER AS THE EVENT GETS CLOSER. ........... ON TUESDAY...SCREAMING H8 JET BLASTS QUICKLY THROUGH NEW ENGLAND AND HEADS INTO CANADA BY LATER TUESDAY AFTERNOON...BUT MUCH OF THE STRONG WINDS SHOULD NOT MIX TO THE SURFACE. HOWEVER...IN THE HIGHER ELEVATIONS OF THE GREEN MOUNTAINS AND BERKSHIRES SHOULD SEE SOME HIGH WIND GUSTS...AND MAY ENTERTAIN WIND ADVISORIES AS THE EVENT GETS CLOSER. SNOW SHOULD CONTINUE IN THE NORTHERN CATSKILLS AND ADIRONDACKS...WITH SOME POTENTIAL MIXING WITH RAIN...AND HIGHS IN THE MID 30S. OTHERWISE...MOST AREAS WILL SEE A COLD RAIN TUESDAY WITH HIGHS IN THE UPPER 30S TO MID 40S. THE UPPER LOW SLOWS AND DRIFTS NORTH AND WEST OF OUR REGION LATER TUESDAY THROUGH WEDNESDAY. WIND ANOMALIES (-4 SD TO -6 SD U WIND ANOMALIES AT 850 MB AND -2.5 SD TO -3.5 SD AT 250 MB) STILL SUGGEST A SLOW MOVING SYSTEM WITH STRONG FORCING FOR A PROLONGED PERIOD OF HEAVY PRECIPITATION...BUT GUIDANCE SOURCES SEEM TO LIFT THE UPPER LOW INTO CANADA FAIRLY QUICKLY. STRONGEST FORCING NOW LOOKS TO BE IN NORTHERN NEW ENGLAND AND POINTS NORTH AND EAST. BOUNDARY LAYER THERMAL GRADIENT NOT AS STRONG AS SOME SIMILAR HISTORICAL STORMS...AND LOW/MID LEVEL MOISTURE FROM ATLANTIC AS GULF OF MEXICO LARGELY CUT OFF FROM THIS SYSTEM...ALTHOUGH UPPER JET AND MOISTURE PLUME SEEN ALOFT. SO THIS STORM MAY HAVE MUCH MORE OF AN IMPACT OUTSIDE OUR FORECAST AREA...BUT STILL RESPECTABLE SNOWS SHOULD BE OBSERVED IN HIGHER ELEVATIONS WITHIN OUR FORECAST AREA. THE BOTTOM LINE IS THAT AS UPPER LOW GRADUALLY DRIFTS INTO CANADA...DEEP WEST FLOW TAKES OVER...AND PRECIPITATION WILL BE LIMITED TO SNOW SHOWER ACTIVITY...AND LAKE ENHANCED PRECIPITATION. PROXIMITY OF UPPER LOW SUGGESTS KEEPING CHANCES FOR SNOW SHOWERS EVERYWHERE TUESDAY NIGHT AND RAIN/SNOWSHOWERS WEDNESDAY...WITH BEST CHANCES IN HIGHER ELEVATIONS AND AREAS NORTH OF THE MOHAWK VALLEY. LOWS TUESDAY NIGHT MID 20S IN MOUNTAINS TO AROUND OR A LITTLE BELOW FREEZING ELSEWHERE. HIGHS WEDNESDAY 30S MOUNTAINS AND AROUND 40 TO LOWER 40S ELSEWHERE. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... SIDED WITH MOS GUIDANCE. THE GFS REMAINS A LITTLE SLOWER THAN THE ECMWF AT LIFTING THE VERTICALLY STACKED THANKSGIVING STORM OUT OF THE AREA...BUT BOTH TRACK IT UP TO THE NORTH AND WEST AT A FAIRLY GOOD CLIP BY FRIDAY. THE SYNOPTIC EVENT WILL BE OVER WITH AT THE START OF THANKSGIVING DAY...BUT LAKE EFFECT WILL COMMENCE ON ITS HEELS...AS THE VERTICAL PROFILE OF THE ENSUING WESTERLY FLOW ON THE BACK SIDE OF THE SYSTEM REMAINS LOW ON SHEAR COMPARED WITH SATURDAY`S MODELS. THE LAKE EFFECT WILL PROBABLY BE A FAIRLY WELL-CONFINED BAND AFFECTING PORTIONS OF THE NORTHERN ADIRONDACKS... AND THIS WILL PROBABLY PERSIST THROUGH THE DAY AND MUCH OF THE OVERNIGHT INTO FRIDAY...WHEN THE WESTERLY FLOW BREAKS DOWN...AS DOES AN APPROACHING COLD FRONT. FOR NOW...HAVE CHC THROUGH MOST OF THE ADIRONDACKS PORTION OF OUR CWA FOR THE OVERNIGHT WED...WITH CHC ALL BUT SOUTHERNMOST CWA DURING THE HEIGHT OF TURKEY DAY...ALTHOUGH FLURRIES MAY LIKELY BE ALL THAT`S HAD AT MOST LOCATIONS OUTSIDE THE BELT. THE WEAKENING COLD FRONT MAY SET OFF SOME MORE RAIN/SNOW SHOWERS AGAIN IN THE WELL-MOISTENED ADIRONDACKS...SO HAVE CHC MAINLY NORTH AND WEST OF THE CAPITAL REGION FRI AND FRI NGT...CHIEFLY UPSLOPE REGIONS MEANWHILE...LOW PRESSURE OF PACIFIC ORIGIN DEEPENS AND TRACKS EAST TO THE DEEP SOUTH...THEN UP THE COAST. BOTH MODELS HAVE IT NEAR CAPE COD SATURDAY NIGHT...WITH SIMILAR CIRCULATION PATTERNS BETWEEN THE SURFACE AND 500 MB...SO HAVE CHC -RA/-SN SAT NGT...THEN BACK TO A LAKE EFFECT FLOW FOR SUNDAY. TEMPERATURES SHOW LITTLE DAY-TO-DAY VARIATION IN PATTERN UNTIL SUNDAY...WHEN THE DEPARTING LOW DRAWS IN MORE COLDER AIR ACROSS THE CWA. MERCURIES SHOULD HAVE NO PROBLEM GETTING TO 40 DEGREES EACH DAY IN THE HUDSON VALLEY. LOWS IN THE 20S WITH SOME ADIRONDACK UPPER TEENS EACH NIGHT BECOME LOWS MOSTLY AROUND 20 SUNDAY NIGHT... WITH SOME LOW TO MID TEENS IN THE ADIRONDACKS. THE MEX MOS VALUES ARE PRETTY CLOSE TO THE FCST VALUES...WITH THE MODEL EFFECTIVELY RECOGNIZING THE COLDER TEMPERATURES AT THE END OF THE PERIOD. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... VFR CONDITIONS ARE EXPECTED PRIOR TO 00Z/TUE WITH HIGH PRESSURE MOVING EASTWARD OFF THE MID ATLANTIC COAST...WHILE A COMPLEX STORM SYSTEM APPROACHES FROM THE MIDWEST AND LOWER MS RIVER VALLEY MONDAY NIGHT THRU TUESDAY. MID AND HIGH CLOUDS WILL PERSIST THIS MORNING THROUGH THE AFTERNOON. CLOUDS WILL CONTINUE TO THICKEN AND LOWER ASSOCIATED WITH THE WARM AIR ADVECTION IN ADVANCE OF A WARM FRONT 00Z/TUE TO 06Z/TUE...WITH RAIN AND SNOW MOVING IN FOR ERN NY. CIGS/VSBYS WILL RAPIDLY ERODE TO AT LEAST MVFR LEVELS EARLY MONDAY EVENING. THE WINDS WILL BE LIGHT FROM THE S/SE AROUND 5 KTS THIS MORNING...BUT INCREASE TO 5-10 KTS IN THE AFTERNOON. THE SOUTHEASTERLY WINDS WILL BE AROUND 10 KTS AT KALB MONDAY EVENING WITH A FEW GUSTS CLOSE TO 20 KTS. AT KGFL...AND KPOU WITH A STRONGER LOW LEVEL INVERSION IN PLACE...THE WINDS WILL BE IN THE 4-7 KT RANGE. A STRONG LOW LEVEL JET /AROUND 2-2.5 KFT AGL/ WILL MOVE OVER THE REGION AFTER 06Z/TUE...SO LOW LEVEL WIND SHEAR GROUPS WILL LIKELY NEED TO BE ADDED LATER TUESDAY MORNING. OUTLOOK... MON NIGHT-TUE...MVFR/IFR. -RA...CHC -SN. LLWS LIKELY. WED-THU...VFR/MVFR. CHC -SHRA/-SHSN. FRI...VFR...NO SIG WX. && .HYDROLOGY... NO HYDROLOGY PROBLEMS THROUGH MONDAY AS IT WILL REMAIN MAINLY DRY WITH ANY PRECIPITATION FALLING AS LIGHT SNOW SHOWERS. A COMPLEX STORM WILL LIKELY BRING SIGNIFICANT PRECIPITATION TO THE REGION MONDAY NIGHT INTO TUESDAY...WITH AN UNSETTLED WEATHER PATTERN TUESDAY NIGHT THROUGH FRIDAY NIGHT WITH PRECIPITATION TAKING THE FORM OF WIDELY SCATTERED TO NUMEROUS SNOW OR MIXED RAIN/SNOW SHOWERS. MIXED PCPN LIKELY MONDAY NIGHT AND TUESDAY...WITH MAINLY SNOW OVER HIGHER TERRAIN WEST OF THE HUDSON VALLEY...MAINLY RAIN IN THE HUDSON VALLEY...AND ABOUT 50-50 MIX OVER THE HIGHER TERRAIN EAST OF THE HUDSON VALLEY. MANY AREAS COULD SEE COULD SEE A TOTAL OF A HALF TO THREE QUARTERS OF AN INCH OF PRECIPITATION...MAINLY RAIN BY LATE TUESDAY. SOME PARTS OF THE CATSKILLS...TACONICS AND BERKSHIRES COULD SEE LOCALLY HEAVIER RAINFALL...AN INCH OR MORE. AT THIS POINT...IT DOES NOT LOOK LIKE FLOODING WILL BE A PROBLEM ASIDE FROM PAVED AREAS WHERE DRAINAGE MAY BE BLOCKED BY PILES OF SNOW OR DEBRIS. HOWEVER A POTENTIAL EXISTS THAT THE STORM COULD BRING MORE RAIN THAN CURRENTLY EXPECTED. FOR DETAILS ON THE RIVERS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...NAS NEAR TERM...KL SHORT TERM...NAS LONG TERM...HELLER AVIATION...TAW HYDROLOGY...NAS ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 300 PM EST MON NOV 24 2008 .SYNOPSIS... 19Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING A NOW HIGHLY AMPLIFIED UPPER LEVEL PATTERN ACROSS NORTH AMERICA. MAIN FEATURE OF NOTE IS A SHARP MID/UPPER LEVEL TROUGH NOW PUSHING EAST OF THE MS VALLEY. INITIAL SHORTWAVE ENERGY IS DROPPING INTO THE SOUTHERN MS VALLEY AND REMAINS WELL DEFINED ON WV IMAGERY WITH MARKED DRYING IN ITS WAKE EXPANDING ACROSS THE ARKLATEX REGION. ANOTHER STRONG PIECE OF UPPER LEVEL ENERGY IS DIVING SOUTH OUT OF WESTERN ONTARIO INTO THE GREAT LAKES. THESE TWO FEATURES WILL CONSOLIDATE OVER THE NEXT 12-18 HOURS INTO AN ENERGETIC UPPER LEVEL DISTURBANCE OVER THE GREAT LAKES AND SOUTHWARD TO THE TENNESSEE VALLEY. ON EITHER SIDE OF THIS TROUGH WE FIND LONGWAVE RIDGING OVER THE INTER-MOUNTAIN WEST AND ALONG THE EAST COAST. SOUTHERN STREAM MOISTURE FEED IS ALSO SEEN MOVING NORTHEAST ACROSS MEXICO AND TOWARD THE NORTHERN GULF COAST. LARGE SCALE LIFT ASSOCIATED WITH MID-LEVEL HEIGHT FALLS IS COMBINING WITH THIS UPPER LEVEL MOISTURE AND VIGOROUS WWA IN THE LOWER LEVELS TO PRODUCE NUMEROUS SHOWERS AND THUNDERSTORMS FROM LA TO THE TN AND OHIO VALLEYS. THIS MAIN AREA OF SHOWERS AND STORM WILL BE APPROACHING OUR WESTERN ZONES OF SOUTHEAST AL AND THE FLORIDA PANHANDLE DURING THE EARLY AND MIDDLE EVENING HOURS. IN THE LOWER LEVELS...SURFACE RIDGING THAT HAS BEEN IN CONTROL OF THE REGION IS WEAKENING AND RAPIDLY MOVING SOUTH AND EAST LATE THIS AFTERNOON IN RESPONSE TO THE DEVELOPING SYSTEM TO OUR NORTHWEST AND ASSOCIATED APPROACH OF A COLD FRONT. THIS FRONT IS CURRENTLY LOCATED FROM THE OHIO VALLEY SOUTHWARD INTO THE CENTRAL TENNESSEE VALLEY AND THEN SOUTHWEST TO LA. A MIX OF SUN AND CLOUDS ACROSS THE AREA INTO THE EARLY EVENING BEFORE THE MAIN BAND OF CLOUDS AND SHOWERS OVERSPREADS FROM THE WEST. .SHORT TERM (TONIGHT THROUGH WEDNESDAY NIGHT)... THERE REMAINS VERY GOOD AGREEMENT AMONG THE MODEL SUITES AS TO THE EVOLUTION OF THE APPROACHING FRONT AND THE UPPER LEVEL DYNAMICS FROM THIS EVENING INTO TUESDAY MORNING. 850MB THETA-E RIDGE AND ASSOCIATED FORCED ASCENT WILL BE ARRIVING ACROSS THE FLORIDA PANHANDLE AND SOUTHEAST ALABAMA EARLY THIS EVENING. ALTHOUGH A STRAY SHOWER OR SPRINKLE IS CERTAINLY POSSIBLE OVER THIS AREA DURING THE REMAINING AFTERNOON HOURS...THE BULK OF THE PRECIP WILL HOLD OFF UNTIL AROUND SUNSET AND THROUGH THE EVENING HOURS. SURFACE INSTABILITY IS EXTREMELY LIMITED WITH SREF PROBS OF EVEN 500 J/KG HOLDING BELOW 5% OVER LAND. HOWEVER...MODELS CONTINUE TO INDICATE THAT WE WILL INITIALLY SEE SOME MARGINAL INSTABILITY ALOFT OVER THE WESTERN ZONES AS SHOWALTER INDICES APPROACH ZERO. WITH THIS IN MIND WOULD NOT BE SURPRISED TO GET A FEW RUMBLES OF THUNDER WITH THE BAND OF SHOWERS. COLD FRONT IS THEN EXPECTED TO STEADILY PUSH SOUTHEAST ACROSS THE AREA THROUGH THE NIGHT AND EXIT THE SOUTHEAST BIG BEND NEAR OR SHORTLY AFTER SUNRISE. INITIAL SHORTWAVE ENERGY IS PROGGED TO SHEAR OUT RAPIDLY TO THE NORTHEAST AS THE MAIN UPPER LOW ORGANIZES WELL TO THE NORTH. AS THIS OCCURS THE LARGE SCALE LIFT OVERHEAD ALL BUT COLLAPSES. MOISTURE AXIS BECOMES RATHER STRUNG OUT INTO THE EASTERN HALF OF THE FORECAST AREA AS WELL. WITH ALL THIS IN MIND SHOULD EXPECT A RATHER SOLID LINE OF RAIN/EMBEDDED STORMS OVER THE WEST THIS EVENING TO WEAKEN AND THIN OUT AS IT MOVES EAST AFTER MIDNIGHT. CURRENT FORECAST POPS SHOWING LIKELY TO CATEGORICAL VALUES OVER THE EASTERN FL PANHANDLE/SOUTHEAST ALABAMA AND PORTIONS OF SOUTHWEST GEORGIA THIS EVENING. THESE POPS TAPER TO ONLY LOW END CHANCE VALUES AFTER MIDNIGHT ACROSS THE FAR EASTERN ZONES APPROACHING THE SUWANNEE RIVER VALLEY. SHOWALTER INDICES SHOW A LESSENING OF THE ELEVATED INSTABILITY INTO OUR EASTERN ZONES AND WILL NOT BRING THUNDER MENTION EAST OF THE APALACHICOLA RIVER. THIS IS SHAPING UP TO BE A HIGH POP/LOW IMPACT EVENT...MEANING THAT ALTHOUGH MANY LOCATIONS WILL SEE A BRIEF PERIOD OF RAINFALL TONIGHT...THE DURATION IS LIKELY TO BE SHORT AND RAINFALL ACCUMULATIONS GENERALLY ON THE LIGHT SIDE. IN FACT...AS THE OVERALL DYNAMICS CONTINUE TO COLLAPSE DURING THE LATE NIGHT HOURS...FAR EASTERN AREA FROM VALDOSTA INTO THE EASTERN FLORIDA BIG BEND MAY ONLY SEE A QUICK LINE OF BROKEN SHOWERS PASS THROUGH WITH VERY LITTLE IN THE WAY OF ACCUMULATION. ANY LINGERING SHOWERS SHOULD EXIT THE SOUTHEAST FLORIDA BIG BEND AROUND SUNRISE TOMORROW WITH CLOUDS RAPIDLY DECREASING THROUGH THE MORNING. EXPECTING A PARTLY TO MOSTLY SUNNY AFTERNOON ALMOST REGION-WIDE WITH A GUSTY NORTH TO NORTHWEST WIND AND HIGH TEMPS WARMING FROM EARLY MORNING LOWS IN THE 40S UP INTO THE 60S. HIGH PRESSURE BUILDS OVERHEAD TUESDAY NIGHT AND REMAINS IN THE VICINITY THROUGH WEDNESDAY NIGHT. WITH THE HIGH SETTLING OVERHEAD AND WITH VERY DRY LOW LEVEL AIR IN PLACE...EXPECTING A GOOD RADIATIONAL COOLING EVENT RESULTING IN YET ANOTHER COLD MORNING. ASSUMING SURFACE WINDS CAN DROP TO CALM (WHICH APPEARS QUITE LIKELY WITH THE FORECAST HIGH POSITION) MANY NORMALLY COLDER LOCATIONS UNDER RADIATIONAL COOLING LOOK TO BOTTOM OUT WITHIN A FEW DEGREES EITHER SIDE OF FREEZING EARLY WEDNESDAY MORNING. HAVE ADDED PATCHY FROST TO ALL AREAS AWAY FROM THE IMMEDIATE COAST DURING THIS TIME AS FROST CAN TAKE HOLD AT GROUND LEVEL EVEN WITH 2 METER TEMPS HOLDING IN THE MIDDLE 30S. A PLEASANT FALL DAY EXPECTED FOR WEDNESDAY WITH PLENTY OF SUNSHINE. MAY SEE SOME INCREASE IN HIGH LEVEL CIRRUS...ESPECIALLY LATE...TO FILTER THE SUN AS GFS/ECMWF SHOWING A WEAK DISTURBANCE APPROACHING IN THE FAST UPPER LEVEL FLOW. HIGHS GENERALLY IN THE MIDDLE 60S. WITH THE SURFACE RIDGE STILL IN PROXIMITY WEDNESDAY NIGHT MAY ONCE AGAIN SEE A FEW AREAS APPROACH FREEZING LATE. BEST CHANCES WEDNESDAY NIGHT TO SEE FROST WILL BE ACROSS THE EASTERN FORECAST AREA...AND ESPECIALLY ACROSS THE SANDIER SOILS OF THE BIG BEND. THIS IS A LOWER CONFIDENCE FORECAST THAN ON TUESDAY NIGHT AS ANY CIRRUS POSSIBLY STILL OVERHEAD WOULD BE ENOUGH TO DISRUPT THE RADIATIONAL COOLING PROCESS AND KEEP TEMPS UP A FEW EXTRA DEGREES. .LONG TERM...(THURSDAY THROUGH MONDAY). CONTINUED AMPLIFIED AND FAST MOVING PATTERN ACROSS THE EASTERN CONUS IS STILL INDICATED THROUGHOUT THE LONG TERM PERIOD. SURFACE HIGH PRESSURE AND FLAT FLOW ALOFT WILL CREATE A PLEASANT THANKSGIVING ACROSS THE SOUTHEAST BEFORE AN APPROACHING WAVE OF LOW PRESSURE ACROSS THE WESTERN GULF COAST STATES BEGINS TO SPREAD EASTWARD FRIDAY AFTERNOON. THIS SOLUTION HAS BEEN GAINING SUPPORT BETWEEN THE GFS AND EURO...AND THE LATEST RUNS OF THESE MODELS CONTINUE TO SUPPORT THIS DEVELOPING STORM SYSTEM. IT APPEARS THAT A DEEPENING SHORT WAVE (ANOTHER IN A SERIES OF MANY) DROPPING OUT OF THE GREAT LAKES STATES ON FRIDAY NIGHT/SATURDAY MORNING WILL HELP PULL THE SURFACE WAVE NORTHEASTWARD OVER THE APPALACHIAN FOOTHILLS AND UP THE EAST COAST THROUGH SATURDAY AFTERNOON. THIS WILL RESULT IN A COLD FRONT PUSHING INTO OUR REGION SATURDAY AFTERNOON WITH GOOD CHANCES OF RAIN EXPECTED. THE TIMING OF THIS SYSTEM HAS DECENT CONSISTENCY BETWEEN THE OPERATIONAL GFS AND EURO...AS WELL AS MANY OF THE GFS ENSEMBLE MEMBERS. THERE ARE SOME DIFFERENCES BETWEEN HOW QUICKLY THIS SYSTEM WILL GET THROUGH THE REGION. HOWEVER...IF THE FRONTAL SYSTEM HOLDS UP OVER OR JUST SOUTH OF OUR FORECAST AREA...IT WON`T REMAIN THERE FOR LONG AS THE OVERALL EAST COAST TROF DEEPENS MORE AND ANOTHER PIECE OF ENERGY SHOULD CLEAR OUR REGION OUT BY THE FIRST OF THE WEEK. MAX TEMPERATURES THROUGHOUT THE FIRST PART OF THE LONG TERM PERIOD SHOULD GENERALLY BE AT OR JUST ABOVE CLIMO. A COOL DOWN BEHIND THE FRONTAL SYSTEM THAT PASSES EARLY SUNDAY MORNING WILL DROP MAX TEMPS BACK INTO THE LOWER 60S BY MONDAY. MIN TEMPS...ASIDE FROM A LIGHT FREEZE ON THURSDAY MORNING WILL WARM EACH DAY THROUGH SUNDAY...AND BE ABOVE NORMAL THESE LAST TWO DAYS. COOLER MINS RETURN BEHIND THE FRONT BY MONDAY MORNING. && .MARINE... HIGH PRESSURE WEAKENS AND SLIDES SOUTHEAST THIS EVENING ALLOWING WINDS TO COME AROUND TO SOUTH AND SOUTHWEST. COLD FRONT WILL CROSS THE WATERS FROM WEST TO EAST LATE THIS EVENING INTO THE EARLY MORNING HOURS WITH A SHARP WINDS SHIFT TO THE NORTHWEST AND NORTH. WINDS WILL INCREASE IN THE WAKE OF THE FRONT TO CAUTIONARY LEVELS. A BRIEF PERIOD OF ADVISORY LEVEL WINDS IS POSSIBLE INTO TUESDAY MORNING...ESPECIALLY OVER THE WESTERN LEGS AND THIS POTENTIAL WILL NEED TO BE MONITORED THIS EVENING. NORTHERLY FLOW WILL REMAIN ELEVATED NEAR CAUTIONARY LEVELS INTO TUESDAY EVENING. WINDS WILL THEN RAPIDLY DIMINISH INTO THE DAYLIGHT HOURS OF WEDNESDAY AS SURFACE HIGH PRESSURE BUILDS OVER THE NORTHEAST GULF OF MEXICO. THIS HIGH WILL REMAIN IN CONTROL OF THE FORECAST WATERS PROVIDING LIGHT WINDS AND SEAS THROUGH THURSDAY BEFORE THE NEXT SYSTEM BEGINS TO APPROACH FROM THE WEST FOR THE EARLY PART OF THE UPCOMING WEEKEND. && .AVIATION... VFR CIGS (AROUND 9K FT) WILL DEVELOP THIS AFTERNOON AHEAD OF AN APPROACHING COLD FRONT. SHRA WILL AFFECT KDHN BY THIS EVENING...THEN THE REST OF THE TERMINALS TONIGHT. MOST OF THE RAIN WILL NOT IMPACT CIGS OR VIS...BUT BRIEF PERIODS OF MVFR CONDITIONS WILL BE POSSIBLE IN ISOLATED +SHRA. WINDS WILL SHIFT TO NORTHWEST BEHIND THE COLD FRONT DURING THE EARLY MORNING HOURS...FOLLOWED BY DECREASING CLOUDS. NORTHWEST WINDS OF 10 KT (GUSTS TO 20 KT) ARE EXPECTED BY MID TO LATE TUESDAY MORNING...ALONG WITH UNLIMITED CIGS AND VIS. KTLH RADAR IMAGERY INDICATED A FIRE (AND SMOKE PLUME) 16 NM SOUTHWEST OF KTLH. SO FAR THE BOUNDARY LAYER WINDS HAVE NOT BEEN ADVECTING THE SMOKE OVER THE TERMINAL...BUT WE WILL WATCH THIS CLOSELY FOR VIS IMPACTS. && .FIRE WEATHER... A COLD FRONT WILL USHER DRIER AIR INTO THE REGION TUESDAY. THE COMBINATION OF DAYTIME HEATING AND THE DRY AIRMASS WILL DRIVE RELATIVE HUMIDITY LEVELS BELOW CRITICAL LEVELS TUESDAY AFTERNOON ACROSS OUR FL ZONES. HIGH DISPERSION VALUES ARE ALSO EXPECTED. THE HUMIDITY MAY BRIEFLY DROP BELOW 25 PERCENT IN OUR GA AND AL ZONES...BUT NOT LONG ENOUGH TO WARRANT A WARNING. RED FLAG CONDITIONS WILL BE POSSIBLE AGAIN WEDNESDAY AFTERNOON. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 47 66 32 65 33 / 60 0 0 0 0 PANAMA CITY 49 66 39 66 45 / 70 0 0 0 0 DOTHAN 43 63 34 65 39 / 80 0 0 0 0 ALBANY 43 62 31 65 34 / 70 0 0 0 0 VALDOSTA 46 64 32 65 33 / 50 05 0 0 0 CROSS CITY 51 69 32 68 32 / 30 15 0 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...RED FLAG WARNING FROM 12 PM EST /11 AM CST/ TO 6 PM EST /5 PM CST/ TUESDAY FOR THE FOLLOWING ZONES: BAY...CALHOUN... COASTAL WALTON...DIXIE...FRANKLIN...GADSDEN...GULF... HOLMES...INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE... LEON...LIBERTY...MADISON...TAYLOR...WAKULLA...WASHINGTON. GM...NONE. && $$ AVIATION/FIRE WEATHER...FOURNIER SYNOPSIS/SHORT TERM/MARINE...MROCZKA LONG TERM...GODSEY fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 945 AM EST MON NOV 24 2008 .SYNOPSIS... 14Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING AN AMPLIFYING UPPER LEVEL PATTERN ACROSS NORTH AMERICA THIS MORNING. MAIN FEATURE OF NOTE IS A SHARPENING MID/UPPER LEVEL TROUGH ACROSS THE MID-SECTION OF THE COUNTY/MS VALLEY. INITIAL SHORTWAVE ENERGY CURRENTLY DROPPING INTO THE SOUTHERN PLAINS/MS VALLEY IS WELL DEFINED ON WV IMAGERY WITH MARKED DRYING IN ITS WAKE EXPANDING ACROSS OK AND MO. ANOTHER STRONG PIECE OF UPPER LEVEL ENERGY IS DIVING SOUTH OUT OF WESTERN ONTARIO INTO THE GREAT LAKES. THESE TWO FEATURES WILL CONSOLIDATE OVER THE NEXT 12-24 HOURS INTO AN ENERGETIC UPPER LEVEL DISTURBANCE OVER THE GREAT LAKES AND SOUTHWARD TO THE TENNESSEE VALLEY. ON EITHER SIDE OF THIS TROUGH WE FIND LONGWAVE RIDING ALONG BOTH THE EAST AND WEST COASTS. SOUTHERN STREAM MOISTURE FEED IS ALSO SEEN MOVING NORTHEAST ACROSS MEXICO INTO THE SOUTHERN MS VALLEY. LARGE SCALE LIFT ASSOCIATED WITH MID-LEVEL HEIGHT FALLS IS COMBINING WITH THIS UPPER LEVEL MOISTURE AND VIGOROUS WWA IN THE LOWER LEVELS TO PRODUCE WIDESPREAD SHOWERS AND THUNDERSTORMS FROM EASTERN TEXAS TO THE TENNESSEE AND OHIO VALLEYS. IN THE LOWER LEVELS...SURFACE RIDGING FROM THE CAROLINA COAST SOUTHWARD INTO NORTHERN FLORIDA WILL CONTINUE TO WEAKEN AND SLIDE EAST THROUGH THE DAY IN RESPONSE TO THE DEVELOPING SYSTEM TO OUR NORTHWEST AND ASSOCIATED APPROACH OF A COLD FRONT. THIS FRONT IS CURRENTLY LOCATED FROM THE OHIO VALLEY SOUTHWARD INTO THE WESTERN TENNESSEE VALLEY AND INTO THE SOUTHERN MS VALLEY. AS THE UPPER LEVEL TROUGH AND SURFACE COLD FRONT CONTINUE TO APPROACH THROUGH THE DAY WILL EXPECT THE CLOUDS ALREADY IN PLACE ACROSS THE NORTHWEST HALF OF THE FORECAST AREA TO CONTINUE TO EXPAND EASTWARD. HOWEVER THIS MAY BE A SLOWER PROCESS THE FURTHER EAST ONE GETS AND STILL EXPECT TO SEE A GOOD DEAL OF SUN WELL INTO THE AFTERNOON OVER THE SOUTHEASTERN BIG BEND FROM PERRY TO CROSS CITY. VERY GOOD AGREEMENT AMONG THE MODEL SUITES AS TO THE EVOLUTION OF THIS FRONT AND THE UPPER LEVEL DYNAMICS THIS EVENING INTO EARLY TUESDAY MORNING. 850MB THETA-E RIDGE AND ASSOCIATED FORCED ASCENT DOES NOT ARRIVE ACROSS THE FLORIDA PANHANDLE/SOUTHEAST ALABAMA UNTIL LATE THIS AFTERNOON AND EARLY THIS EVENING. ALTHOUGH A STRAY SHOWER CAN NOT BE RULED OUT OVER THIS AREA DURING THE EARLY AND MIDDLE AFTERNOON HOURS...THE BULK OF THE PRECIP WILL HOLD OFF TILL NEAR DARK AND INTO THE EVENING HOURS. SURFACE INSTABILITY IS EXTREMELY LIMITED WITH SREF PROBS OF EVEN 500 J/KG HOLDING BELOW 5% OVER LAND. HOWEVER...THERE IS INITIALLY SOME MARGINAL INSTABILITY ALOFT PROGGED BY GUIDANCE AS SHOWALTER INDICES APPROACH ZERO OVER THE WESTERN ZONES DURING THE EVENING HOURS. WITH THIS IN MIND WOULD NOT BE SURPRISED TO GET A FEW RUMBLES OF THUNDER WITH THE BAND OF SHOWERS...HOWEVER ANY STRONG STORM POTENTIAL APPEAR VERY UNLIKELY. COLD FRONT IS THEN EXPECTED TO STEADILY PUSH SOUTHEAST ACROSS THE AREA THROUGH THE NIGHT AND EXIT THE SOUTHEAST BIG BEND NEAR OR SHORTLY AFTER SUNRISE TUESDAY MORNING. INITIAL SHORTWAVE ENERGY IS PROGGED TO SHEAR OUT RAPIDLY TO THE NORTHEAST AS THE MAIN TROUGH ORGANIZES WELL TO THE NORTH. AS THIS OCCURS THE LARGE SCALE LIFT OVERHEAD ALL BUT COLLAPSES. MOISTURE AXIS BECOMES RATHER STRUNG OUT INTO THE EASTERN HALF OF THE FORECAST ARE AS WELL. WITH ALL THIS IN MIND SHOULD EXPECT A RATHER SOLID LINE OF RAIN/EMBEDDED STORMS OVER THE WEST THIS EVENING TO WEAK AND THIN OUT AS IT MOVES EAST AFTER MIDNIGHT. SHOWALTER INDICES SHOW A LESSENING OF THE ELEVATED INSTABILITY INTO OUR EASTERN ZONES AND WILL NOT BRING THUNDER MENTION EAST OF THE APALACHICOLA RIVER. FAR EASTERN AREA FROM VALDOSTA INTO THE EASTERN FLORIDA BIG BEND MAY ONLY SEE A QUICK LINE OF LIGHTER SHOWERS PASS THROUGH LATE TONIGHT WITH VERY LITTLE IN THE WAY OF ACCUMULATION. ANY LINGERING SHOWERS SHOULD EXIT THE SOUTHEAST FLORIDA BIG BEND SHORTLY AFTER SUNRISE WITH CLOUDS RAPIDLY DECREASING THROUGH THE MORNING. EXPECTING A PARTLY TO MOSTLY SUNNY AFTERNOON ALMOST REGION-WIDE WITH A GUSTY NORTH TO NORTHWEST WIND AND HIGH TEMPS IN THE LOWER TO MIDDLE 60S. && .MARINE... HIGH PRESSURE WEAKENS AND SLIDES EAST INTO THIS EVENING ALLOWING WINDS TO COME AROUND TO THE SOUTHEAST AND EVENTUALLY SOUTH LATER TODAY. COLD FRONT CROSSES THE WATERS FROM WEST TO EAST TONIGHT WITH A SHARP WINDS SHIFT TO THE NORTHWEST AND NORTH. WINDS WILL INCREASE IN THE WAKE OF THE FRONT TO CAUTIONARY LEVELS WITH A PERIOD OF ADVISORY LEVEL WINDS POSSIBLE INTO TUESDAY AFTERNOON. NORTHERLY FLOW WILL REMAIN ELEVATED NEAR CAUTIONARY LEVELS THROUGH TUESDAY NIGHT. WINDS WILL THEN RAPIDLY DIMINISH INTO THE DAYLIGHT HOURS WEDNESDAY AS SURFACE HIGH PRESSURE BUILDS OVER THE NORTHEAST GULF OF MEXICO. THIS HIGH WILL REMAIN IN CONTROL OF THE FORECAST WATERS PROVIDING LIGHT WINDS AND SEAS THROUGH THURSDAY BEFORE THE NEXT SYSTEM BEGINS TO APPROACH FROM THE WEST FOR THE EARLY PART OF THE UPCOMING WEEKEND. && .AVIATION... VFR CIGS (6-12K FT) WILL INCREASE FROM NORTHWEST TO SOUTHEAST TODAY AHEAD OF AN APPROACHING COLD FRONT. SURFACE WINDS WILL QUICKLY VEER FROM EAST-SOUTHEAST TO SOUTH AHEAD OF THE FRONT...BUT WILL REMAIN LESS THAN 10 KT. SCATTERED TO NUMEROUS SHRA WILL AFFECT KDHN BY LATE AFTERNOON OR EARLY EVENING...THEN THE REST OF THE TERMINALS TONIGHT. BRIEF PERIODS OF MVFR VIS/CIGS WILL BE POSSIBLE IN THESE SHRA. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 68 44 65 31 63 / 20 50 00 00 00 PANAMA CITY 69 48 64 34 64 / 40 60 00 00 00 DOTHAN 66 41 63 31 62 / 50 60 00 00 00 ALBANY 65 42 62 31 59 / 30 60 00 00 00 VALDOSTA 69 43 64 31 63 / 10 50 00 00 00 CROSS CITY 72 48 65 31 65 / 10 30 05 00 00 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...FIRE WX WATCH TUE AFTN ALL ZONES. GM...NONE. && $$ AVIATION...FOURNIER SYNOPSIS/UPDATE/MARINE...MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 1242 AM EST MON NOV 24 2008 .AVIATION... VFR CONDITIONS EXPECTED TO PERSIST THROUGH THE MORNING HOURS AND THROUGH THE DAY. THERE IS AN AREA OF CLOUDINESS IN THE VICINITY OF THE BAHAMAS WITH ISOLATED SHOWERS. AROUND 10Z ITS POSSIBLE TO HAVE VCSH FOR THE EAST COAST TERMINALS. OTHERWISE STRATOCU FROM 5 TO 7 KFT WILL STREAM IN OFF THE ATLANTIC WATERS THE REMAINDER OF THE EARLY MORNING HOURS. A WEAK LAND BREEZE IS POSSIBLE FOR THE EAST COAST TERMINALS...MORE LIKELY FOR KMIA...KOPF AND KTMB. THE EAST COAST TERMINALS WILL LIKELY HAVE AN EASTERLY SEA BREEZE NEAR 12 KNOTS THIS AFTERNOON. 60 && .PREV DISCUSSION... /ISSUED 955 PM EST SUN NOV 23 2008/ UPDATE...ON A MINOR TWEAK TO THE WINDS NEEDED THIS EVENING TO REFLECT CURRENT TRENDS, HOWEVER THAT MAINLY AFFECTED THE BAY AND ATLANTIC ZONES. ALL OTHER ELEMENTS UNCHANGED AS THE PREVIOUS FORECAST REMAINS ON TARGET. /TINGLER MARINE...GUIDANCE CONTINUES TO SHOW WINDS ACROSS THE ATLANTIC ZONES REMAINING MARGINAL FOR A SMALL CRAFT ADVISORY, AND INDEED FOWEY HAS BEEN AT 20 TO 23 KNOTS THIS EVENING FOR THE PAST FEW HOURS. SO, HAVE DECIDED TO PLAY IT SAFE AND KEEP THE SCA GOING THROUGH THE NIGHT FOR THE BAY AND ATLANTIC ZONES. ADDED THE BAY SINCE EASTERLY WINDS WILL AFFECT THE CENTRAL SECTIONS. THE MIAMI- DADE AND BROWARD COASTAL WATERS WILL THE ZONES MOST AFFECTED SINCE THE GRADIENT IS TIGHTER TO THE SOUTH, HOWEVER ALSO KEPT THE PALM BEACH WATERS IN AS WELL DUE TO A RECENT SHIP REPORT OF 20KTS. /TINGLER PREV DISCUSSION... /ISSUED 720 PM EST SUN NOV 23 2008/ AVIATION... VFR CONDITIONS WILL PERSIST ACROSS ALL SOUTH FLORIDA TERMINALS THIS FORECAST CYCLE...WITH THE PRIMARY CONCERN BEING WINDS. ALL AVAILABLE GUIDANCE NOW SUGGESTS THAT PRESSURE GRADIENT AND RESULTING ENE FLOW WILL STRENGTHEN OVER THE ATLANTIC TONIGHT... WHICH MAY BE THE KEY FACTOR IN DEVELOPMENT OF A LAND BREEZE. AT THIS TIME...WILL INDICATE NO LAND BREEZE AT PBI/FLL...AS EASTERLY FLOW SHOULD BE SUFFICIENTLY STRONG TO PREVENT A PENETRATION THIS CLOSE TO THE COAST. HOWEVER...AT TERMINALS FURTHER INLAND...WILL INDICATE WINDS BACKING TO NNW AND DECREASING IN THE PREDAWN HOURS ON MONDAY. WINDS WILL REMAIN LIGHTER AND FROM THE NE OVERNIGHT AT KAPF...WITH ESE FLOW OF 8-12 KNOTS EXPECTED AT ALL TERMINALS DURING THE DAY ON MONDAY. OTHERWISE...CLOUD CONDS OF FEW050/SCT070 WILL PREVAIL THROUGH THE PERIOD...AND ENOUGH THREAT FOR SHRA TO INCLUDE VCSH ALONG THE EAST COAST OVERNIGHT. MANY THANKS TO ZMA CWSU FOR EXCELLENT THOUGHTS AND INPUT FOR THIS FORECAST. 70/DD PREV DISCUSSION... /ISSUED 234 PM EST SUN NOV 23 2008/ DISCUSSION...HIGH PRESSURE WILL PULL AWAY FROM THE MID ATLANTIC COAST TONIGHT THROUGH MONDAY...RESULTING IN OUR PREVAILING WINDS TURNING MORE EASTERLY. MOISTURE WILL INCREASE SLIGHTLY...THOUGH BELIEVE THE GFS/NAM ARE A BIT TOO BULLISH ON THIS. KEPT SLIGHT CHANCE POPS NEXT FEW DAYS FOR THE ATLANTIC COAST...BUT OTHERWISE MOSTLY DRY WEATHER IS EXPECTED TO CONTINUE. MOST CHALLENGING PART OF THE FCST IS AGAIN ON THE LAND BREEZE AND ITS EFFECTS ON TEMPS AGAIN TONIGHT...AND MONDAY NIGHT AS WELL. GFS/NAM AND EVEN THE WRF DO NOT SHOW THE LAND BREEZE DEVELOPING TONIGHT. HOWEVER...THE PATTERN IS NOT CHANGING MUCH AND SO WE BELIEVE IT WILL OCCUR. THE NAM/WRF LOOK WAY TOO AGGRESSIVE WITH WINDS OVERNIGHT...AND THEY START THE DEVELOPMENT OF THE LAND BREEZE EARLY ON BEFORE THE WINDS SURGE TAKES OVER SWITCHING WINDS BACK NE. SINCE THIS SURGE LOOKS TO AGGRESSIVE...DECIDED TO DISCOUNT THIS. GIVEN THE FACT THAT GOOD RADIATIONAL COOLING IS AGAIN EXPECTED IN A STILL RATHER DRY AIRMASS...DECIDED TO BRING THE LAND BREEZE ACROSS MUCH OF THE EAST COAST METRO AREAS AGAIN TONIGHT...BUT NOT QUITE TO THE COAST...REASON BEING THAT IT MADE IT TO THE COAST JUST FOR AN HOUR THIS MORNING...AND ANY SLIGHT INCREASE IN THE NE-E WIND OVERNIGHT WOULD HOLD IT AT BAY. SHOULD MENTION THAT THE RUC IS ACTUALLY FOLLOWING RIGHT ALONG WITH OUR EXPECTATIONS TONIGHT. THE MAIN IMPACT THE FCST ON THE LAND BREEZE HAS IS WITH REGARDS TO TEMPS...AS IT CAN FLUCTUATE 5-10F DEGREES ON EITHER SIDE OF THE BOUNDARY...AS SEEN OVER THE PAST FEW MORNING`S. KEPT PATCHY FOG IN THE FCST TONIGHT AND MON NIGHT. MON NIGHT LOOKS TO BE MOST OPTIMAL...AHEAD OF A PRE-FRONTAL TROUGH. GFS/ECMWF STILL SHOW THE COLD FRONT MOVING ACROSS THE AREA TUESDAY NIGHT INTO WED MORNING...WITH A PRE-FRONTAL TROUGH MOVING BY ON TUESDAY. AFTER TEMPS WARM FINALLY TO NEAR 80 AHEAD OF THE FRONT TUESDAY...A SLIGHT COOL DOWN WILL OCCUR ON WEDNESDAY BEHIND THE FRONT. MOISTURE WILL REMAIN LIMITED...SO MOSTLY DRY WEATHER IS ANTICIPATED. MADE NO CHANGES TO THE EXTENDED FCST. THE DRY NOVEMBER WEATHER PATTERN LOOKS TO CONTINUE. BOTH GFS/ECMWF SHOW A GRADUAL WARMING TREND LATE IN THE WEEK AND INTO NEXT WEEKEND...WITH YET ANOTHER COLD FRONT EXPECTED EITHER SUNDAY OR MONDAY...DEPENDING ON THE MODEL...AND JUST TOO EARLY TO TELL AT THIS POINT IN TIME...BUT THE PARADE OF FRONTS LOOK TO CONTINUE. MARINE...DECIDED TO EXTEND THE SMALL CRAFT ADVISORY FOR THE ATLANTIC WATERS THROUGH THIS EVENING...AS GULF STREAM SEAS WILL LIKELY NOT START SUBSIDING UNTIL LATE EVENING AND OVERNIGHT DUE TO THE FACT THAT WINDS WILL REMAIN FROM A MORE NE DIRECTION BEFORE BECOMING EASTERLY LATER TONIGHT. OTHERWISE...WINDS OVER THE NEXT FEW DAYS WILL SLACKEN LEADING TO IMPROVING MARINE CONDITIONS. THE PRE-FRONTAL TROUGH WILL MOVE ACROSS THE AREA TUESDAY...SWITCHING WINDS TO W-NW...AND THE ACTUAL COLD FRONT WILL MOVE ACROSS THE AREA TUE NIGHT INTO EARLY WED MORNING...WITH A BRIEF WIND SURGE EXPECTED BEHIND IT...BUT GUIDANCE SUGGESTS ONLY 15-20 KT AND NOT TOO PROLONGED. FIRE WEATHER...RH`S HAVE BEEN DOWN AGAIN TO NEAR 40 PERCENT AS SOME DRY AIR HAS MIXED DOWN. MOISTURE WILL INCREASE JUST A TAD ON MONDAY. SLIGHT DRYING IS EXPECTED TUESDAY BEHIND A PRE-FRONTAL TROUGH...BUT NOT EXPECTED TO BE DRY ENOUGH AT THIS TIME TO RESULT IN CRITICAL RH`S. HOWEVER...WILL MONITOR TRENDS...BECAUSE TUE WILL BE THE WARMEST DAY OF THE WEEK...AND IF MORE DRYING OCCURS BETWEEN THE PRE-FRONTAL TROUGH AND THE ACTUAL COLD FRONT...THEN RH`S COULD FALL LOWER THAN FCST. THE DRIEST AIR WILL ADVECT IN ACROSS THE AREA BEHIND THE FRONT ON WEDNESDAY. TRENDED DEW POINTS/RH`S DOWN...THOUGH NOT AS LOW AS THE NAM AT THIS TIME...WHICH DROPS DEW POINTS TO THE LOWER 30S NW INTERIOR TO THE LOWER 40S SE. WE LIKELY WILL NEED TO CONTINUE A DECREASING TREND IN COMING FCSTS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 75 60 79 57 / 20 20 10 10 FORT LAUDERDALE 77 62 79 61 / 20 20 10 10 MIAMI 77 62 80 62 / 20 20 10 10 NAPLES 76 61 77 57 / 10 10 10 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR AMZ630- AMZ650-AMZ651-AMZ670-AMZ671. GM...NONE. && $$ LONG TERM...15/JR SHORT TERM/AVIATION...60/BD fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 539 PM CST MON NOV 24 2008 .DISCUSSION... 258 PM CST NOT MUCH CHANGE TO PREVIOUS FCST. AFTERNOON VISIBLE SATLT IMAGERY SHOWS MID LVL CIRCULATION CENTER NOW OVR WRN LK SUPERIOR...DROPPING SSEWD. BY 12Z TUES...UPR LOW CENTER IS FCST TO BE OVR OH. LEADING EDGE OF ASSD VORT LOBE/JET MAX NOW DIVING SWD ACROSS SRN MN-WRN WI WILL BE PASSING ACROSS FA THIS EVENING...BRINGING COLD ADVECTION STRATOCU AND A FEW FLURRIES AS REINFORCING SHOT OF COLD AIR SWEEPS TROUGH MIDWEST IN ASSOCIATION WITH DEEPENING CYCLONE TO E. EXPECT CLOUDS TO GRUDGINLY ERODE FROM W-E DURG TUESDAY AS DEEP CLOSED SYSTEM LIFTS ENEWD TO WRN NY AND STRONG CYCLC FLOW BEGINS TO EASE. AGAIN...THIS WILL LIKELY BE A SLOW CLRG PROCESS AS BANDS OF CLOUDINESS CONTINUE TO ROTATE SWD ACROSS WRN GRTLKS TIL LATE IN THE DAY TUES. AS THIS VERTICALLY STACKED SYS SLOWLY RELAXES ITS INFLUENCE WHILE SLOWLY SPINNING DOWN THRU MIDWEEK...SKIES OVR AREA WILL BE MAINLY CLR IN REGION OF INCRSG SUBSIDENCE/HGT RISES. LOW LVL ADVECTION DURING THIS PERIOD IS FCST TO REMAIN WEAK...SO NOT TOO MUCH IN THE WAY OF MID/HI LVL CLOUDINESS EXPECTED. WITH LOW SFC DEW POINTS...EXPECT DECENT DIURNAL SWINGS TUES-THURS DESPITE TIME OF YR. MOS NUMBERS DO A PRETTY GOOD JOB REFLECTING THIS TREND...WITH COLD NIGHTS AND SLOW DAY-TO-DAY MODERATION IN HIGH TEMPS...PEAKING THANKSGIVING DAY WHEN MAX/S SHOULD REACH WELL INTO 40S. THURSDAY NIGHT INTO FRIDAY...GFS BRINGS POSITIVELY TILTED SHRT WAVE SEWD ACROSS PLAINS STATES...AND ACROSS MIDWEST. LLVLS WILL REMIAN QUITE DRY WITH STRONG BAROCLINIC ZONE DRAPED ACROSS DIXIE. GIVEN THIS AND THE LACK OF DYNAMICS...WILL KEEP FCST DRY...BUT WITH INCR IN MID/HI LVL OVERCAST. SHEARED NATURE OF THIS TROF ALSO SUGGESTS LITTLE TEMPERATURE CHG AFTER WIND SHIFTS TO NW ON FRIDAY. WILL ALSO KEEP EXTENDED PORTIONS OF FCST /SAT-MON/ DRY. MODELS AND HPC PROGNOSTICS HAVE SETTLED ON PATTERN EVOLVING BACK INTO ONE OF PERSISTENCE...WITH DEEP TROFFING OVER ERN CANADA AND THE GRTLKS...WITH MOISTURE BEARING SYSTEM SHUNTED WELL TO S. AS A RESULT HAVE TRENDED DRY WITH MINOR AMTS OF PRECIP GENERALLY STAYING N OF AREA...FROM UPR GRTLKS SEWD IN CLOSER PROXIMITY TO UPR LOW. WILL ALSO GO WITH TREND OF TEMPS RUNNING A LTL BELOW SEASONAL NORMS. MERZLOCK && .AVIATION... 539 PM CST 0000 UTC TAFS...FOCUS THIS EVENING IS ON POTENTIAL FOR MVFR CONDITIONS WITH LIGHT SNOW SHOWERS OR FLURRIES LATER TONIGHT AS PAIR OF STRONG MID LEVEL VORT MAXIMA ROTATE SOUTH ACROSS FORECAST AREA. WINDS/GUSTS ALSO A CONCERN WITH STRENGTHENING LOW LEVEL COLD ADVECTION OVERNIGHT. EARLY EVENING SATELLITE IMAGERY INDICATES ONE AFOREMENTIONED VORT CENTER NOW OVER FAR NORTHWEST IL...AND ANOTHER DROPPING SOUTHWARD INTO UPPER MISSISSIPPI VALLEY. MODELS HAVE SIMPLIFIED THESE INTO MORE OF A SINGULAR FEATURE...THOUGH 21Z RUC SEEMS TO HAVE CAPTURED THE DUAL/INDIVIDUAL NATURE BETTER. BASED ON SATELLITE/METAR TRENDS UPSTREAM AND RELYING ON RUC FORECAST SOUNDINGS WILL START OUT WITH VFR CEILINGS WHICH ARE SPREADING ACROSS AREA AT THIS TIME...AND WILL MAINTAIN A TEMPO PERIOD LATE EVENING/OVERNIGHT THOUGH SLIGHTLY LATER TIMING FOR MVFR CONDITIONS IN LIGHT SNOW SHOWERS WITH ARRIVAL OF COLDER AIR AND STEEPENING LOW LEVEL LAPSE RATES. UPSTREAM OBS INTO KMSP AREA INDICATE CEILINGS MAINLY VFR... DROPPING TO MVFR IN 1500-2500 FOOT RANGE WITH VISIBILITY 3-P6SM IN SNOW SHOWERS. SNOW SHOWERS RELATIVELY SCATTERED IN NATURE...THOUGH WILL MONITOR RADAR TRENDS THROUGH THE EVENING FOR ANY INCREASE IN COVERAGE OR DETERIORATION IN FLIGHT CATEGORIES. RUC INDICATES SECOND VORT TRANSLATING SOUTHEAST OF AREA AFTER 09Z TIMEFRAME WITH SUBSIDENCE/DRYING IN MID LEVELS BRINGING THREAT OF PRECIP TO AN END LATER TONIGHT. WRF/GFS CONTINUE THIS TREND TUESDAY AS UPPER LOW PULLS SLOWLY OFF TO OUR EAST. SURFACE WINDS HAVE BACKED A BIT WESTERLY AND WEAKENED/DECOUPLED AHEAD OF WEAK SURFACE TROUGH REFLECTION FROM INITIAL VORT MOVING INTO NORTHWEST IL. WILL LIKELY SEE A SLIGHT SHIFT MORE NORTHWEST IN NEXT FEW HOURS AS THIS TROUGH PROPAGATES ACROSS AREA...THEN MORE SOLIDLY OVERNIGHT AS LAPSE RATES STEEPEN WITH COLDER AIR MOVING IN. WITH WEAKER LOW LEVEL STABILITY WILL LIKELY SEE SOME GUSTINESS RETURN...INTO THE LOW 20 KNOT RANGE. THIS TO CONTINUE THROUGH TUESDAY MORNING...THOUGH NORTHWEST WINDS SHOULD GRADUALLY DECREASE DURING THE AFTERNOON AS SURFACE LOW PULLS AWAY TO THE EAST. RATZER && .MARINE... 154 PM CST LOW PRESSURE OVER SOUTHERN LOWER MICHIGAN DEEPENS AS IT MOVES SLOWLY EASY TO SOUTHERN LAKE HURON OVERNIGHT. RESULTING INCREASING PRESSURE GRADIENT AND LOW LEVEL COLD ADVECTION WILL RESULT IN WINDS INCREASING TO GALE FORCE TONIGHT. ALREADY GUSTING TO AROUND 25 KNOTS ON SOUTHERN LAKE MICHIGAN. WHILE THE LOW WILL CONTINUE TO MOVE EAST TO THE UPPER ST. LAWRENCE VALLEY BY TUESDAY NIGHT...IT WILL ALSO CONTINUE DEEPENING...KEEPING WINDS UP ON LAKE MICHIGAN THROUGH INTO THE MORNING BEFORE THEY START TO GRADUALLY DIMINISH AS A HIGH PRESSURE RIDGE GRADUALLY MOVES EAST AND REACHES THE MISSISSIPPI VALLEY BY LATE IN THE DAY. CURRENT ENDING TIME OF GALE WARNING LIKELY EXTENDING TOO FAR INTO THE AFTERNOON BUT WILL LEAVE AS IS FOR NOW. FLOW REMAINS NORTHWESTERLY AS THE LOW LIFTS NORTHWARD FROM THE ST. LAWRENCE TOWARD JAMES BAY THURSDAY AND THURSDAY NIGHT. A LOW AND ACCOMPANYING COLD FRONT WILL MOVE EAST INTO THE WESTERN GREAT LAKES THURSDAY NIGHT WITH BACKING TO WEST AND VEERING TO NORTHWEST...THEN REMAINING PREVAILING NORTHWEST AS A LARGE RIDGE OF HIGH PRESSURE BUILDS ACROSS THE NORTHERN ROCKIES AND CENTRAL AND SOUTHERN PLAINS WITH A SURFACE CYCLONE OVER EASTERN HUDSON BAY. TRS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN UNTIL 6 P GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ745-LMZ777-LMZ779- LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 6 PM TUESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO BURNS HARBOR UNTIL 6 PM TUESDAY. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 553 AM CST MON NOV 24 2008 .DISCUSSION... 307 AM CST MAIN FORECAST CHALLENGE REMAINS WITH THE SHORT TERM PERIOD PRECIPITATION TYPE AND WHETHER ANY OF THE POSSIBLE SNOW WILL ACCUMULATE OVER MONDAY MORNINGS RUSH HOUR. THE NAMS WARMER SOLUTION FROM YESTERDAY APPEARS TO HAVE BEEN THE WINNER WITH THIS EVENT AS THE SECONDARY SOUTHERN LOW HAS PROPAGATED INTO EASTERN IOWA LEAVING OUR REGION IN THE WARM SECTOR FOR THE TIME BEING. WITH THE WARM AIR ADVECTION TAKING PLACE...THE LOW LEVEL TEMPERATURE PROFILES HAVE BEEN WELL ABOVE FREEZING WITH AN ACARS SOUNDING OUT OF ORD SHOWING TEMPS UP TO 44F AT 4KFT. TEMPERATURES ACROSS THE REGION REALLY ARENT AS COLD AS YOU WOULD LIKE TO SEE FOR A SNOW EVENT...WHICH IS MAINLY DUE TO FACT THAT THERE ISNT A STRONG HIGH TO OUR NORTH...RATHER ANOTHER SURFACE LOW THAT IS BOGARTING ALL THE COLD AIR. SFC TEMPS ARE IN THE UPPER 20S/LOW 30S BACK IN THE DAKOTAS AND 850MB TEMPS RANGE FROM 0 TO -2 FROM DUBUQUE BACK TO FARGO. ALL IN ALL...FEEL AS THOUGH THIS DOESNT HAVE THE BEST SETUP BUT WITH ENOUGH EVAPORATIVE COOLING AND SLIGHTLY COOLER AIR WRAPPING IN ON THE BACKSIDE OF THIS WEAK LOW THAT SOME VERY WET SNOW WILL REMAIN A POSSIBILITY THIS MORNING...PARTICULARLY FURTHER NORTH UP ALONG THE WISCONSIN BORDER. A FEW OBS HAVE COME IN WITH UNKNOWN PRECIP...BUT THIS AND EVERYWHERE ELSE IN NORTHEAST ILLINOIS AND NORTHWEST INDIANA HAS JUST BEEN RAIN SO FAR THIS MORNING. AS OF 3AM...MOST OF THE SNOW WAS CONFINED TO SOUTHERN WISCONSIN UP TOWARD MSN AND WEST OF THERE. WILL HAVE THE BEST SHOT FOR ANY SNOW THIS MORNING FROM 12-15Z WORKING FROM WEST TO EAST ACROSS THE FORECAST AREA. WILL KEEP SOME VERY MINOR TENTHS OF ACCUMULATION UP ALONG THE WI/IL BORDER SINCE SOIL TEMPS HAVE DROPPED INTO THE 30S WITH THE RECENT COLD SPELL WE HAVE BEEN UNDER MOST OF NOVEMBER. SNOW RATIOS WILL BE VERY LOW...ON THE ORDER OF 9 TO 1 OR LESS WITH THE WETNESS OF THIS SNOW. AS THE TWO SYSTEMS MERGE MONDAY MORNING...THE PRECIP SHOULD COME TO AN END FAIRLY QUICKLY BEFORE 18Z AND SKIES ARE EXPECTED TO CLEAR OUT A BIT AND LET THE SUN OUT IN THE AFTERNOON. THIS SHOULD HELP TEMPERATURES TO BRIEFLY CLIMB UP TO AROUND 40 OR SO. SKIES WILL CLOUD UP AGAIN TOWARD EVENING AS THE CORE OF THE UPPER LOW DIVES DOWN THROUGH WISCONSIN ON INTO NORTHEAST ILLINOIS AND SOUTHERN LAKE MICHIGAN. THIS COLD PUNCH OF AIR ALONG WITH SOME POSITIVE VORTICITY ADVECTION SHOULD PROVIDE ENOUGH FORCING TO SEE SOME SCATTERED FLURRIES OVERNIGHT INTO TUESDAY MORNING. AFTER ALL THIS EXCITEMENT PASSES INTO NEW ENGLAND AND STALLS OUT...OUR REGION WILL BE LEFT IN WEAK NORTHWESTERLY FLOW ALOFT WITH RIDGING AT THE SFC. THIS IS GOOD NEWS FOR ANY TRAVELERS WEDNESDAY NIGHT INTO FRIDAY AS SKIES WILL MAINLY BE CLEAR THROUGH THIS PERIOD AND DRY...ALBEIT SLIGHTLY COLDER THAN NORMAL FOR THIS TIME OF YEAR. HALBACH && .AVIATION... 1200 UTC TAFS...A MIX OF RAIN AND SNOW IS CHANGING OVER TO MOSTLY SNOW THIS MORNING AS EVAPORATIVE COOLING QUICKLY DROPS THE LOWER LEVELS OF THE ATMOSPHERE BELOW FREEZING. ACARS DESCENT SOUNDING INTO ORD AT 11Z DEPICTS THIS WELL. BOTH CIGS AND VSBYS HAVE DROPPED TO IFR OR LIFR AS THE CENTER OF LOW PRESSURE PASSES DIRECTLY OVERHEAD. RUC/NAM/GFS FORECAST SOUNDINGS HAVE RH VALUES DROPPING RAPIDLY BY MID TO LATE MORNING WHICH SUGGESTS CONDITIONS WILL IMPROVE CONSIDERABLY BY MID-DAY...THOUGH A FEW LINGERING SNOW SHOWERS ARE POSSIBLE IN ANY REMAINING LOW STRATUS. WINDS WILL INCREASE THIS EVENING AND OVERNIGHT UNDER THE INFLUENCE OF A TIGHTENING PRESSURE GRADIENT...AND ADDITIONAL RAIN OR SNOW SHOWERS ARE POSSIBLE AS THE BACK END OF THE LOW SPINS ACROSS THE AREA BEFORE MOVING OFF TO THE EAST. LENNING && .MARINE... 326 AM CST A SURFACE LOW MOVING ACROSS NORTHERN ILLINOIS EARLY THIS MORNING WILL PASS ACROSS THE SOUTHERN PORTION OF THE LAKE AND STRENGTHEN ABOUT 10MB BY THIS EVENING AS IT MERGES WITH ANOTHER LOW DROPPING OUT OF CANADA. NORTH TO NORTHWEST GALES ARE EXPECTED TO DEVELOP THIS EVENING AND CONTINUE THROUGH TUESDAY AS THE GRADIENT TIGHTENS BETWEEN THIS FEATURE AND A CENTER OF HIGH PRESSURE MOVING ACROSS THE NORTHERN PLAINS. WINDS WILL DIMINISH TUESDAY EVENING AS THE HIGH PRESSURE MOVES INTO THE UPPER MISSISSIPPI VALLEY. WESTERLY WINDS GENERALLY ARE EXPECTED TO CONTINUE FOR THE REMAINDER OF THE WEEK. LENNING && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...LMZ745...NOON MONDAY TO 6 PM MONDAY. GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ745-LMZ777-LMZ779- LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...6 PM MONDAY TO 6 PM TUESDAY. SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744...NOON MONDAY TO 6 PM TUESDAY. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 1237 PM CST MON NOV 24 2008 .SHORT TERM...TODAY SURFACE LOW PRESSURE IS EXITING FAR SE IOWA EARLY THIS MORNING AND LIGHT PRECIP HAS ENDED OVER FAR EASTERN COUNTIES. THE UPPER TROUGH WILL CONTINUE TO DIG INTO THE STATE TODAY.THE GFS/RUC ARE MORE AGGRESSIVE WITH CAA IN NORTHERN IOWA THIS AFTERNOON...COMPARED TO THE NAM. THE NAM INITIALIZED A BIT TOO WARM REGARDING THE AIRMASS TO THE NORTH...SO WENT WITH A BLEND OF NAM/GFS FORECAST SOUNDINGS FOR AFTERNOON HIGHS. THIS WAS CLOSE TO THE FWC/NGM MOS WITH SOME MINOR DOWNWARD ADJUSTMENTS IN THE SOUTH. THERE MAY BE A FEW FLURRIES OUT OF THE AFTERNOON STRATOCU IN THE MCW/ALO AREAS...ALTHOUGH RH IN THE SPZ IS MARGINAL. SOUNDINGS GO DRY ADIABATIC TO NEAR 850MB...AND WINDS AT THE TOP OF THE MIXED LAYER SUGGEST GUSTS INTO THE 30S. .LONG TERM...TONIGHT THROUGH SUNDAY STRONG UPPER LEVEL LOW NOW ACROSS LAKE WINNIPEG...WILL DIVE SOUTH THROUGH THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES REGION TONIGHT. THE SYSTEM WILL HAVE VERY LIMITED MOISTURE TAGGING ALONG THOUGH STILL POSSIBLE TO SQUEEZE A FEW FLURRIES OUT THIS EVENING NEAR MCW AND ALO. OTHERWISE...BETTER CHANCES FOR LIGHT SNOW WILL BE EAST OF THE MISSISSIPPI RIVER. THE SYSTEMS CONNECTION AT THE SFC WILL NOT BE WELL ESTABLISHED WITH LITTLE SFC REFLECTION BESIDES A WEAK COLD FRONT DROPPING SOUTH. THE SYSTEMS BIGGEST EFFECT ON TEMPERATURES FOR TUESDAY WILL BE DUE TO WARM ADVECTION IN THE MID LEVELS BETWEEN 700-500 MB AND COLD ADVECTION BETWEEN 925-800 MB. THIS WILL RESULT IN LIMITED MIXING POTENTIAL ON TUESDAY WITH AN INVERSION ABOVE 900 MB AND COOLER THAN TODAY WHEN BETTER MIXING OCCURS. THE UPPER LOW WILL LINK UP WITH SHORT WAVE ENERGY NOW MOVING THROUGH SOUTHERN IOWA AND MISSOURI AND CREATE A DEEP CLOSED LOW OVER THE NORTHEASTERN CONUS AND WILL SLOW THE FLOW OVER THE MIDWEST TUESDAY INTO EARLY THURSDAY. WEAK HIGH PRESSURE AND DRY AIR WILL BE IN PLACE DURING THIS PERIOD ALONG WITH LIGHT NORTHWEST FLOW AND SEASONAL TEMPERATURES. THE 850 MB THERMAL RIDGE IS EXPECTED TO PASS THROUGH IOWA ON THURSDAY...HOWEVER MUCH LIKE TONIGHT...WEAK COLD ADVECTION IS ANTICIPATED TO TAKE PLACE BELOW 900 MB AND EFFECTIVELY STRENGTHEN THE INVERSION IN PLACE. THIS WILL LIMIT HIGH TEMPERATURES ON THURSDAY TO NEAR CLIMATOLOGY WITH MIXING ONLY TO 950-925 MB. THE 06Z NAM IS MORE PROGRESSIVE WITH THE LOW LEVEL COLD ADVECTION ON THANKSGIVING DAY. REGARDLESS...EXPECT GOOD TRAVELING CONDITIONS ON THURSDAY. SOME DIFFERENCES AMONG SOLUTIONS REMAIN FRIDAY AND INTO THE WEEKEND THOUGH OVERALL TRENDS ARE TO SUPPRESS THE SOUTHERN PLAINS SYSTEM EVEN FURTHER SOUTH AS ANOTHER COLD FRONT BRINGING ANOTHER PUSH OF COOLER AND DRIER AIR SETTLES SOUTH ON FRIDAY. THE GEM IS CURRENTLY FARTHEST NORTH WITH THE PRECIPITATION TO NEAR THE IA/MO BORDER. && .AVIATION...24/18Z SCNDRY CDFNT DROPPING S ACRS MN AND WILL BRING WITH IT AN AREA OF VFR AND INTMT MVFR STRATUS IN ITS WAKE. CLOUDS WILL MOVE INTO NERN IA TWD SNST AND SPRD OVR ABOUT THE NERN HLF BFT EXITING BFR SNRS. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM/AVIATION...MS NOV 08 LONG TERM...DONAVON ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 1157 PM CST SUN NOV 23 2008 .AVIATION...FIRST THING TO MENTION IS THE SMOKE ISSUE AT KLCH WHICH BROUGHT VISIBILITIES TO BELOW A MILE FOR A FAIR CHUNK OF THE EVENING. VISIBILITY HAS RISEN BACK TO 10SM RECENTLY BUT HAVE INCLUDED PREVAILING FOR THE EARLY PART OF THE FORECAST IN CASE SMOKE RETURNS. OTHERWISE EXPECT SLIGHT RESTRICTIONS TO VIS ALL SITES ON AT LEAST AN OFF AND ON BASIS OVERNIGHT. REGIONAL 88DS CONTINUE TO SHOW VERY LIGHT SHOWERS OR VIRGA MOVING NE TOWARD THE UPPER SE TX/SWRN LA COAST. HAVE CONTINUED EARLIER TREND OF BRINGING SCATTERED LIGHT SHOWERS INTO KLCH/KBPT BY SUNRISE AND BY MID-MORNING FOR REMAINING TAF SITES. EXPECT RAIN TO SPREAD ACROSS THE AREA AS THE COLD FRONT PASSES WEST TO EAST FROM LATE MORNING THROUGH MID-AFTERNOON. EXPECT CLEARING SKIES/VFR BY LATE IN THE PERIOD. 25 && .PREV DISCUSSION... /ISSUED 938 PM CST SUN NOV 23 2008/ UPDATE... ONLY UPDATE TO THE GRIDS THIS EVENING IS TO POPS/WX/QPF. RADAR MOSAIC SHOWS A BAND OF SHOWERS OVER THE GULF WATERS SOUTH OF HOUSTON/GALVESTON BAY. THIS ACTIVITY IS LIFTING SLOWLY NE AND BOTH RUC AND NAM APPEAR TO HAVE A HANDLE ON CURRENT TRENDS WITH INCREASING PRECIP OVER OUR SWRN ZONES AND WESTERN COASTAL WATERS OVERNIGHT AS LOW LEVEL FLOW OFF THE SFC BECOMES MORE SWRLY. LOWERED POPS TO 20 PERCENT AREAWIDE FOR THE REMAINDER OF THE EVENING...INCREASING TO 30 PERCENT AFTER MIDNIGHT FOR THE LOWER SE TX ZONES AND COASTAL WATERS MAINLY WEST OF CAMERON. REMAINDER OF FORECAST LOOKS GOOD. UPDATED ZONES HAVE BEEN SENT. 24 PREV DISCUSSION... /ISSUED 707 PM CST SUN NOV 23 2008/ AVIATION...MAIN CHALLENGE THIS TAF PACKAGE ISSUANCE IS TIMING OF THE ONSET OF PRECIPITATION. REGIONAL 88DS SHOW MAINLY LIGHT SHOWERS... MUCH OF IT PROBABLY JUST VIRGA ATTM...OVER THE GULF OFF THE MIDDLE TEXAS COAST MOVING NWD. MODEL PROJECTIONS SHOW PRECIP SPREADING OVER THE AREA FROM THE SOUTHWEST AND WEST STARTING TOWARD 12Z... ALTHOUGH LIKE LAST NIGHT THE GFS APPEARS TO BE A LITTLE WETTER AND FASTER THAN THE NAM. THUS HAVE TIMED THE PREVAILING POPS IN THE TAFS WITH THIS IN MIND. BUT UNTIL THEN FOR THE OVERNIGHT JUST STUCK WITH VFR CEILINGS GRADUALLY LOWERING...ALONG WITH SOME LIGHT RESTRICTIONS TO VISIBILITY AS WINDS LOOK SUFFICIENT FOR PREVENTING FOG FORMATION. 25 PREV DISCUSSION... /ISSUED 240 PM CST SUN NOV 23 2008/ DISCUSSION...A RATHER MILD AND PLEASANT AFTERNOON ONGOING ACROSS THE REGION. DESPITE CONSIDERABLE MID LEVEL CLOUDINESS...WARMING SOUTHERLIES HAVE MANAGED TO WARM TEMPS INTO THE UPPER 60S NORTH...LOW 70S SOUTH. DEWPOINTS GENERALLY RUNNING FROM 15 TO 20 DEGREES ABOVE THAT OF 24 HOURS PRIOR. LOCAL RADAR INDICATING JUST A BIT OF VIRGA OVER CENTRAL LOUISIANA. NEXT FRONTAL PASSAGE CONTINUES ON TRACK FOR MONDAY. LATEST MOS GUIDANCE SHOWING LESS PRE-FRONTAL ACTIVITY DEVELOPING ACROSS THE REGION TONIGHT. HAVE ADJUSTED GRIDS/POPS DOWN ACCORDINGLY. WILL HOWEVER MAINTAIN LIKELY POPS FOR MONDAY WITH GOOD LOW LEVEL CONVERGENCE DEVELOPING ALONG BOUNDARY...WITH DEEP OMEGAS/LIFT ALSO ACCOMPANYING FRONT. SUFFICIENT SPEED OF SYSTEM WILL EFFECTIVELY LIMIT ANY SIGNIFICANT WIDESPREAD RAIN AMOUNTS. HIGH PRESSURE BECOMES REESTABLISHED FOR TUESDAY AND WEDNESDAY. RETURN FLOW SETS UP THURSDAY AHEAD OF NEXT FRONTAL PASSAGE WHICH APPEARS LIKELY PER LONG RANGE MODELS ON FRIDAY. AVIATION...OVERCAST SKIES WILL CONTINUE FOR THE REMAINDER OF THE AFTERNOON INTO THIS EVENING AS SOUTHWEST FLOW AHEAD OF AN ADVANCING SHORT WAVE PULLS EAST PAC MOISTURE OVER THE REGION. ISENTROPIC LIFT IS EXPECTED TO BE WEAK...ALONG WITH SOME RELATIVELY DRY AIR BETWEEN THE SURFACE AND 10K FEET...AND THUS ANY PRECIPITATION WILL BE JUST SOME SPRINKLES OR VIRGA. CEILING HEIGHTS WILL CONTINUE TO BE AT VFR LEVELS. SOUTHERLY WINDS ARE EXPECTED TO INCREASE LATER TONIGHT INTO EARLY MONDAY AS SHORT WAVE CONTINUES TO ADVANCE TOWARD THE AREA. THESE WINDS WILL HELP INCREASE MOISTURE VALUES WITH GUIDANCE TIME HEIGHTS SHOWING OVER 80 PERCENT RH BETWEEN THE SURFACE TO OVER 20K FEET BY 24/12Z. THIS WILL HELP LOWER CEILING HEIGHTS TO BETWEEN 3K-5K FEET WITH A FEW SHOWERS DEVELOPING FROM WEST TO EAST DURING THE OVERNIGHT. WITH BOUNDARY LAYER WINDS EXPECTED BETWEEN 15 AND 20 KNOTS AND SOME LIFT SEEN BY PROGGED PVA IN THE LOW LEVELS...ANY FOG FORMATION WILL BE PATCHY IN NATURE WITH SOME MVFR VISIBILITIES POSSIBLE. SHOWERS ARE EXPECTED TO BE ON THE INCREASE AFTER 24/12Z FROM WEST TO EAST AS STRONGER LIFT FROM AN APPROACHING COLD FRONT TAPS INTO THE ABUNDANT MOISTURE. RUA MARINE...A MODEST SOUTHERLY FLOW WILL CONTINUE TONIGHT AHEAD OF AN ADVANCING COLD FRONT. THE FRONT WITH SHOWERS AND THUNDERSTORMS WILL MOVE ACROSS THE NORTHWEST GULF MONDAY FOLLOWED BY A STRONG OFFSHORE FLOW. && .PRELIMINARY POINT TEMPS/POPS... KLCH 60 73 47 69 44 / 20 70 10 0 0 KBPT 62 74 46 70 44 / 30 70 10 0 10 KAEX 58 69 42 67 40 / 20 70 10 0 10 KLFT 58 71 48 66 43 / 20 70 10 0 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...NONE. && $$ la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1020 PM EST TUE NOV 25 2008 .SYNOPSIS... AN UPPER LEVEL LOW PRESSURE SYSTEM WILL REMAIN OVER THE NORTHEAST THROUGH WEDNESDAY. REINFORCING COLD AND BLUSTERY CONDITIONS THROUGH MIDWEEK. HIGH PRESSURE WILL BUILD INTO THE AREA DURING THE LATTER HALF OF THE WEEK. A COLD FRONT IS EXPECTED BY THE END OF THE WEEK...AHEAD OF ANOTHER LOW PRESSURE SYSTEM FOR THE SOUTHEAST AND EASTERN SEABOARD TOWARD THE BEGINNING OF NEXT WEEK. && .NEAR TERM /OVRGNT/... RCVD A SPOTTER REPORT OF 5" IN DOWNTOWN FROSTBURG. HV ADDED WRN ALLEGANY AND MINERAL TO THE WRNG AREA. DID A SLTLY EARLY UPDATE TO THE ZNS BASED ON WHAT`S HAPPENING ON THE WRN FRINGE OF OUR CWA. RCVD A REPORT AT 8 PM OF 8 1/2" IN BAYARD. FM WHAT WE`VE LOOKED AT - SREF..AND RUC HRR BEING KEY...WE EXPECT TO SEE AT LEAST 6 MORE HRS OF MDT-HVY SNOWFALL IN WRN GRANT/PENDLETON. WINT STORM WRNG ALREADY UP FOR OUT THERE...BUT HV RAISED THE TOTALS TO UP TO A FOOT. PRVS DSCN... WX TNGT WILL BE RESULT OF THIRD SHRTWV TROF MOVG SEWD AROUND BACK SIDE OF UPR LOW. LOW LVL FLOW ALONG WRN ZONES HAS BACKED TO SWLY THIS AFTN IN RESPONSE TO APRCHG WAVE. WITH PASSAGE OF UPR WAVE...ASSOCIATED CDFNT WILL MOVE THRU...WITH WINDS BCMG WLY TO WNWLY. THIS MAY RESTORE WEAK UPSLP COMPONENT TO WINDS...AND MAY ENHANCE SNOW TOTALS SLGTLY. MAINTAINED ISOLD-SCT CVRG OF PCPN N CNTRL ZONES TNGT ALONG TRACK OF SHRTWV TROF. && .SHORT TERM /WEDNESDAY/... CLD CVR ERODES DURG MRNG SRN ZONES...ALTHOUGH XPCD TO PERSIST ELSEWHERE. MAXIMA SIMILAR TO TDA IN AREAS WITH FEWER CLDS TMW. SNOW SHOWERS TO CONT WRN SLOPES THRU MID DAY TMW...BUT PCPN CHCS SHUD DECR REMAINDER OF FCST AREA AS UPR LOW LIFTS NWD. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... THE EXTENDED HAS BECOME MORE UNCLEAR. NO MAJOR STORMS ON THE HORIZON...BUT GENERAL DISAGREEMENT BETWEEN MODELS BASICALLY FROM D2 ONWARD. THE FIRST MISHANDLING OCCURS W/ THE FRIDAY FRONTAL SYSTEM...WHERE THE GFS AT LEAST HOLDS ONTO A PIECE OF PREV RUNS. A TIGHTLY PACKED UPPER CLOSED LOW WILL SHOOT SWD OVER THE WRN GRT LKS ON THU. A WEAKENING UPPER LOW OVER THE DESERT SW WILL LAG BEHIND THE GRT LKS LOW. THE RESULT WILL BE A DEVELOPMENT OF PRECIP MUCH FURTHER S OF THE DEEPENING UPPER TROF. THE POSITIVELY TILTED UPPER TROF AXIS WILL SLIDE EWD ACROSS THE OH VLY ON FRI. ACCORDING TO THE 12Z GFS...THE SFC LOW WILL DEVELOP ACROSS THE DEEP SOUTH AND MOVE E ACROSS THE I-20 CRDR...KEEPING MUCH OF THE WIDESPREAD PRECIP FAR SOUTH OF THE MID ATLC. THE 00Z EUROPEAN INITIALLY HAS THE SAME IDEA...THEN SQUELCHES THE SOUTHEASTERN SYSTEM BY SEPARATING THE UPPER ENERGY INTO A SMALLER UPPER WAVE ACROSS THE MIDWEST AND THE GRT LKS TROF AXIS EXITING OFF THE COAST ON FRI...W/ LITTLE MORE THAN LIGHT UPSLOPE FOR THE CNTRL APPALACHIANS. THE REMAINDER OF THE 00Z RUN SWINGS ANOTHER UPPER WAVE ACROSS THE GRT LKS FOR EARLY NEXT WEEK...MORE TYPICAL NW FLOW AND ANOTHER QUICK LOW PRESSURE SYSTEM DEVELOPING ACROSS THE MID MISSISSIPPI VLY FOR THE END OF NEXT WEEK /COMPARABLE TO THE ONE THE JUST MOVED THROUGH ON MONDAY/. THE RESULTING AMBIGUITY BROUGHT ON CAUSE FOR A CHANGE IN POPS FOR THE WEEKEND ESPECIALLY. LOW CHANCE POPS FOR FRI...EXPECTING A WEAK COLD FRONT TO SLIDE ACROSS THE REGION LATER IN THE DAY. IF THE GFS SWLY PROG IS A BETTER VALUE FOR THE WEEKEND...THEN ENOUGH LOW LEVEL MOISTURE WILL PUSH NWD AHEAD OF THE APPROACHING UPPER TROF FOR AT LEAST ISOLATED SHOWERS FRI AFTN...BUT NOW THE BULK OF THIS ACTIVITY LOOKS TO BE ACROSS THE SRN PORTIONS OF THE CWA. LOOKING THE NEW 12Z ECMWF...THE MODEL IS NOW A BIT MORE ONBOARD W/ THE GFS DEVELOP WIDESPREAD PRECIP ACROSS SOUTHEAST...BUT STILL A BIT SLOW. THIS RESULTS IN A DEEPER BACKSIDE DIGGING UPPER ACROSS THE UPPER MIDWEST AND STRONGER COASTAL LOW OFF THE MID ATLC COAST LATE SUNDAY. A COUPLE OF TRANSITION HIPRES DAYS EARLY NEXT WEEK AND ANOTHER UPPER LOW OVER THE GREAT LAKES FOR MID WEEK. SO...THIS RUN NOT MAKING THE MED-LONG RANGE MUCH MORE CLEAR. EITHER WAY...THIS FORECAST SHOULD BE A RETURN OF NEAR NORMAL HIGHS TO THE REGION...IN THE U40S/L50S FOR DAYTIME HIGHS. MUCH OF THE UPCOMING WEEK WILL BE DRY...BUT AT LEAST WINDS LOOK TO STAY FAIRLY WEAK...EVEN WITH SEVERAL INCOMING UPPER VORT MAX/S. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... VFR CONDS XPCTD AT THE MAJOR AIRPORTS OVRNGT. MRB MAY SEE CIGS DROP TO MVFR. THE REST OF THE WEEK SHOULD HAVE LITTLE CONCERN FOR ADVERSE WX...OUTSIDE OF A WEAK COLD FRONT ON FRIDAY AND A POSSIBLE LOW PRESSURE SYSTEM SLIDING UP THE COAST ON SUN/MON. WINDS SHOULD BE LIGHT FOR THE NEXT SEVERAL DAYS AND LITTLE IF ANY PRECIP THRU THE REST OF THE WORK WEEK. && .MARINE... SMALL CRAFT ADZY CONTS THIS EVE THRU TMW AS INSTBY TNGT AND CDFNT TMW WILL ALLOW GUSTS TO MIX TO SFC. LITTLE CAUSE FOR CONCERN OF SCA CONDITIONS THROUGH THE REMAINDER OF THE FORECAST PERIOD. A WEAK COLD FRONT EXPECTED TO MOVE ACROSS THE REGION ON FRIDAY. A POSSIBLE COASTAL LOW PRESSURE SYSTEM FOR SUN/MON...THO TIMING AND STRENGTH ARE STILL VERY UNCERTAIN. THE REST OF THIS WEEK SHOULD SEE MAINLY LIGHT WINDS ACROSS THE WATERS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...WINTER WEATHER ADVISORY UNTIL 1 PM EST WEDNESDAY FOR MDZ501. VA...WINTER WEATHER ADVISORY UNTIL 1 PM EST WEDNESDAY FOR VAZ021. WV...WINTER WEATHER ADVISORY UNTIL 1 PM EST WEDNESDAY FOR WVZ503. WINTER STORM WARNING UNTIL 1 PM EST WEDNESDAY FOR WVZ054-501. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST WEDNESDAY FOR ANZ530>537. && $$ UPDATE...WOODY! PRVS...MRK/GMS md AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1210 PM EST TUE NOV 25 2008 UPDATED AVIATION DISCUSSION FOR 18Z TAF ISSUANCE .SYNOPSIS... ISSUED AT 419 AM EST 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWS RIDGING COVERING MUCH OF THE WESTERN HALF OF THE U.S. AND IMMEDIATELY ALONG THE EAST COAST...WITH A TROUGH IN-BETWEEN OVER THE WESTERN GREAT LAKES WHICH CONTAINS AN UPPER LOW NEAR DETROIT. COLDEST AIR OF THE UPPER TROUGH REMAINS ON THE WEST SIDE PER 00Z RAOB ANALYSIS OF 850MB TEMPS...WITH READINGS OF -14C AT INL AND -11C AT MPX. FARTHER EAST ACROSS THE TROUGH...TEMPS WARM TO -9C AT CWPL AND GRB AND TO -5C AT APX. THE TROUGH IS ALSO FAIRLY MOIST...AT LEAST IN THE LOW LEVELS AS LATEST 11-3.9 UM IMAGERY AND SFC OBS SHOWS LOW CLOUDS COVERING MUCH OF ONTARIO...EASTERN LAKE SUPERIOR AND ALL OF MI. CWPL SOUNDING REFLECTS THIS BY SATURATION FROM THE SFC TO 850MB. THIS MOISTURE... COMBINED WITH THE COOL AIR AND A BLUSTERY NORTHERLY FLOW ON SUPERIOR HAVE GENERATED SOME LAKE ENHANCED SNOW SHOWERS...HOWEVER MUCH OF THESE HAVE DIMINISHED AS OF 08Z. SYNOPTIC SNOW...ASSOCIATED WITH THE COLD CONVEYOR BELT AROUND A 1001MB SFC LOW IN SRN LAKE HURON...IS MOSTLY CONFINED TO LOWER MI. TO THE WEST...A SFC RIDGE EXTENDS FROM MN INTO NW ONTARIO...WHICH IS LOCATED JUST TO THE EAST OF AN UPPER RIDGE AXIS IN EASTERN MANITOBA. 00Z BIS SOUNDING SHOWS THE DRY AIR ASSOCIATED WITH THE SFC RIDGE...WITH DEWPOINT DEPRESSIONS OF 40C OR GREATER BTWN 700-850MB. THIS DRY AIR HAS BEEN MAKING IT INTO THE CWA...NOTED BY MOSTLY CLEAR SKIES OVER THE NW HALF OF WESTERN LAKE SUPERIOR AND LOWERING DEWPOINTS OVER THE CWA (26F NOW AT STDM4 AND 28 AT P53). THIS DRIER AIR MAY HAVE BEEN THE CAUSE OF THE END OF THE LAKE ENHANCED PCPN...IN ADDITION TO THE FACT THAT THE AIRMASS IS NOT THAT COLD TO BEGIN WITH AS NOTED BY THE 00Z APX 850MB TEMP. WEST OF THE AFOREMENTIONED UPPER RIDGE AXIS IS A SHRTWV TROUGH CROSSING SASKATCHEWAN. && .DISCUSSION... ISSUED AT 419 AM EST MAIN FORECAST CONCERN IS PCPN CHANCES THROUGH FRI...GIVEN LATEST RADAR IMAGERY NOT NEARLY AS IMPRESSIVE AS EARLIER EXPECTED. TODAY...UPPER LOW NEAR DETROIT IS PROGGED TO SLIDE EASTWARD INTO PA THIS AFTN AND THEN INTO WRN NEW YORK STATE BY 00Z. WITH THE LOW MOVING FARTHER AWAY FROM HERE...THE RIDGE AXIS TO OUR NW AND THE SFC RIDGE IS ALLOWED TO BUILD INTO WESTERN LAKE SUPERIOR. THEREFORE... DRIER AIR WILL CONTINUE TO ADVECT INTO THE CWA. GIVEN THE FACT THAT LITTLE PCPN IS OCCURRING ON RADAR AT THE MOMENT AND FURTHER DRY AIR ENTERING THE CWA...HAVE DRIED OUT THE FORECAST FOR TODAY. MODELS HAVE BEEN OVERDOING THE AMOUNT OF LAKE ENHANCEMENT FROM THIS EVENT...AND EVEN THE LATEST 06Z RUNS CONTINUE TO DO SO...BUT TRENDS FROM THE MODELS ARE SHOWING LESS QPF. STILL HAVE MAINTAINED A DECENT AMOUNT OF CLOUD COVER FOR TODAY...PARTICULARLY IN THE NORTH CENTRAL AND EASTERN CWA FROM MOISTURE TRAPPED UNDER A LOWERING INVERSION. OVER THE WEST AND SOUTH CENTRAL...SOME OF THE LAKE EFFECT COULD CLEAR OUT...BUT MID/HIGH CLOUDS ASSOCIATED WITH THE SHRTWV IN SASKATCHEWAN ARE EXPECTED TO DROPPING IN DURING THE AFTN. COLDER 850MB AIR IN OVER THE CWA AND CLOUD COVER SHOULD LIMIT THE AMOUNT OF HEATING TODAY. READINGS WILL END UP A FEW DEGREES COOLER THAN YESTERDAY. TONIGHT...SHRTWV CURRENTLY OVER SASKATCHEWAN IS PROGGED TO DROP SOUTH INTO WESTERN LAKE SUPERIOR BY 12Z WED AS IT DIGS INTO THE UPPER TROUGH OVER THE EASTERN GREAT LAKES. IMPACTS FROM THIS SHRTWV SHOULD BE MOSTLY THE MID/HIGH CLOUDS AHEAD OF IT...SINCE DRY AIR ASSOCIATED WITH THE SFC RIDGE REMAINS IN PLACE OVER WESTERN LAKE SUPERIOR. TO THE EAST...THE UPPER LOW OVER WRN NEW YORK STATE LIFTS TO THE NW IN RESPONSE TO STRONG RIDGING BUILT AHEAD OF IT IN THE CANADIAN MARITIMES. THE UPPER LOW IS A BIT TOO FAR EAST TO HAVE MUCH IMPACT OVER THE CWA...BUT A PERSISTENT NORTHERLY LOW LEVEL FLOW WILL BE CONTINUING DOWN EASTERN SUPERIOR. SOUNDINGS FOR ERY DO NOT LOOK THAT FAVORABLE FOR PCPN...WITH ONLY A 1000-3000 FT THICK LAYER OF CLOUD DUE TO THE LOW INVERSION. THEREFORE HAVE LOWERED POPS TO 20 FOR THE EASTERN CWA. WAS TEMPTED TO REMOVE POPS ENTIRELY GIVEN LACKLUSTER PERFORMANCE OF PCPN CURRENTLY...BUT THE DROP FROM 50 IS TOO MUCH FOR ONE FORECAST. NEEDLESS TO SAY THERE SHOULD STILL BE PLENTY OF CLOUD COVER BETWEEN THE MID/HIGH CLOUDS AND THE TRAPPED LOW LEVEL MOISTURE. THESE CLOUDS WILL HELP HOLD TEMPS UP... ESPECIALLY IN THE EASTERN CWA WHERE THE NORTH FLOW CONTINUES TO BRING WARMER AIR IN OFF EASTERN SUPERIOR. COLDEST READINGS EXPECTED IN GOGEBIC AND IRON COUNTIES...WHERE A PERIOD OF CLEARING IS POSSIBLE AFTER THE MID CLOUDS EXIT LATE TONIGHT. READINGS THERE COULD DROP INTO THE UPPER TEENS AS SUGGESTED BY MET/MAV GUIDANCE. WEDNESDAY...UPPER LOW IN FAR SE ONTARIO LIFTS A BIT FARTHER TO THE NW...BUT STILL WELL AWAY FROM HERE. SHRTWVS ROTATING AROUND THE LOW ARE ALSO FAR ENOUGH AWAY FROM HERE COMPARED TO WHAT IT LOOKED LIKE YESTERDAY SUCH THAT NO SYNOPTIC PCPN IS EXPECTED. PERHAPS SOME SNOW GETS INTO THE WAWA ONTARIO AREA LATER IN THE AFTN AS THE 00Z NAM SUGGESTS...BUT THAT WOULD BE IT FOR THE WESTWARD EXTENT OF THE SYNOPTIC SNOW. MODELS ALSO SHOW SOME LIGHT PCPN COMING OFF EASTERN LAKE SUPERIOR...SIMILAR TO TONIGHT...WITH COLD ENOUGH AIR TO GENERATE LAKE ENHANCED OR LAKE EFFECT PRECIPITATION. HAVE DECIDED TO KEEP SOME 20 POPS IN THE FORECAST FOR THE EASTERN CWA...BUT AGAIN COULD SEE IT BEING DRY AS WELL SEEING WHAT IS HAPPENING RIGHT NOW. ALSO...DO NOT WANT HAVE A HUGE DROP IN POPS FROM THE PREVIOUS FORECAST. THE REST OF THE CWA WILL CONTINUE TO BE UNDER THE INFLUENCE OF THE RIDGE OF HIGH PRESSURE STUCK IN THE MN/WESTERN LAKE SUPERIOR AREA...MAINTAINING DRY WEATHER. A BIT MORE SUN COULD OCCUR AS WELL...ESPECIALLY ALONG THE WI BORDER AWAY FROM LAKE MOISTURE TRAPPED UNDER THE INVERSION. WITH 850MB TEMPS PROGGED FROM -4C WEST TO -8C CENTRAL/EAST AND MORE SUN...HIGHS SHOULD GENERALLY BE IN THE MID 30S...WARMEST SOUTH CENTRAL WITH DOWNSLOPING NW FLOW. WED NIGHT...UPPER LOW IS PROGGED TO LIFT FARTHER NORTH...WHILE TO THE WEST A FAIRLY STRONG SHRTWV IS SHOWN TO DROP DOWN INTO EASTERN NORTH DAKOTA. THE 00Z GFS/ECMWF/UKMET KEEP THE SHRTWVS ROTATING AROUND THE UPPER LOW FARTHER TO THE WEST THAN THE 00Z NAM...AND HAVE DECIDED TO FOLLOW THE MAJORITY. THIS IS REINFORCED BY THE FACT THAT THE SHRTWV TROUGH DROPPING DOWN INTO EASTERN NORTH DAKOTA SHOULD PUSH RIDGING TOWARDS UPPER MI...NOT ALLOWING THE UPPER LOW TO RETREAT WESTWARD. SO IT COMES DOWN TO LAKE EFFECT/ENHANCED PCPN AGAIN...WITH 20 POPS CONFINED TO THE EASTERN CWA. THE WEST AND CENTRAL AREAS CONTINUE TO BE DOMINATED BY THE SFC RIDGE...WHICH GETS A PUSH EASTWARD THROUGH THE NIGHT AS UPPER RIDGING FORMS AHEAD OF THE SHRTWV. THIS MEANS THAT THE WEST AND CENTRAL REMAIN DRY WITH SOME CLOUDS AROUND OFF LAKE SUPERIOR. SHOULD THESE CLOUDS NOT EXIST...WILL NEED TO WATCH TEMPS INLAND...ESPECIALLY WITH THE SFC RIDGE BUILDING IN. HAVE CONTINUED MENTION OF UPPER TEENS INLAND WITH 20S ELSEWHERE...BUT IF SKIES CLEAR THEN LOW TEENS AS SUGGESTED BY MEX COOP GUIDANCE WOULD BE MORE REALISTIC. THU THROUGH FRI...THIS PERIOD OF THE FORECAST IS DOMINATED BY THAT SHRTWV TROUGH THAT DROPPED DOWN INTO EASTERN NORTH DAKOTA. ALREADY THIS TROUGH IS FASTER COMPARED TO WHAT THE 00Z RUNS FROM YESTERDAY SHOWED. MODELS DISAGREE ON THE SPEED OF THE TROUGH...WITH THE ECMWF AND UKMET FASTER COMPARED WITH THE GFS/NAM. HPC PREFERENCE WAS TO FOLLOW THE FASTER SCENARIO...WHICH MAKES SENSE GIVEN THE FASTER MOTION TO BEGIN WITH. THIS TROUGH SHOULD CROSS INTO CENTRAL WI BY 00Z FRI...THEN HEAD INTO THE EASTERN GREAT LAKES BY 12Z FRI. SINCE THE TROUGH IS GOING JUST TO OUR SOUTH...THE TRACK IS FAVORABLE FOR A FRONTOGENETICAL BAND OF SNOW TO MOVE ACROSS THE CWA. BEST GUESS TIMING FOR THE BAND WOULD BE BTWN 18Z AND 06Z. INCLUDED POPS IN THE FORECAST...GENERALLY 30-50 FOR NOW...BUT IF TRENDS CONTINUE MORE INCREASES WILL BE NEEDED. SINCE THE TROUGH IS A FAST MOVER AND DOES NOT HAVE A LOT OF MOISTURE TO WORK WITH...SINCE IT IS COMING OUT OF CENTRAL CANADA INSTEAD OF THE SRN PLAINS...ONLY LIGHT ACCUMULATIONS OF SNOW ARE EXPECTED. IN THE WAKE OF THE SHRTWV...COOLER AIR FILTERS FOR LATER THU NIGHT INTO FRI...WITH 850MB TEMPS DROPPING TO AROUND -10C. THEREFORE...SOME LAKE EFFECT SHOULD START UP...MOSTLY AFFECTING THE NW FLOW SNOWBELTS. HIGHS ON THU WILL BE SLIGHTLY COOLER THAN WED SINCE CLOUDS ARE EXPECTED TO RAPIDLY APPROACH WITH THE TROUGH. LOOK FOR FRI TO BE A LITTLE COOLER TOO AS THE COLD ADVECTION STARTS UP. NO CHANGES MADE BEYOND FRI. LOOKS LIKE A GENERAL LAKE EFFECT PATTERN INTO THE WEEKEND WITH GENERAL TROUGHING SETTING UP OVER THE GREAT LAKES AND 850MB TEMPS IN THE -10 TO -12C RANGE. MEAN WIND DIRECTION LOOKS TO BE NW...SO NW FLOW SNOWBELTS WOULD HAVE THE BETTER CHANCE FOR LAKE EFFECT. HIGHS AND LOWS EXPECTED TO STAY AROUND NORMAL GIVEN THE 850MB READINGS. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... OVERALL...EXPECT MVFR CIGS TO PREVAIL AT KCMX/KSAW THRU THIS FCST PERIOD AS LOW-LEVEL MOISTURE REMAINS TRAPPED BELOW A SLIGHTLY LOWERING INVERSION. CLOUDS MAY OCCASIONALLY SCATTER OUT AT KCMX AND PERHAPS KSAW THIS EVENING...BUT IT APPEARS LOW-LEVEL MOISTURE WILL REMAIN SUFFICIENT THAT BKN MVFR CIGS SHOULD BE THE RULE THRU THE FCST PERIOD. AS A WEAK SFC RIDGE NOSES INTO WESTERN UPPER MICHIGAN THIS AFTERNOON WINDS WILL BECOME MORE NWRLY AND LIGHTEN TO LESS THAN 10 KNOTS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRES JUST E OF LAKE HURON WILL MEANDER E ACROSS THE LOWER GREAT LAKES REGION THRU WED. AS THIS OCCURS...NRLY WINDS WILL GRADUALLY DECREASE TODAY AND TONIGHT. OVER ERN LAKE SUPERIOR...EXPECT 20-30KT WINDS TO DECREASE TO 15-25KT THIS AFTN AND TO 10-20KT TONIGHT. THERE MAY BE A FEW GUSTS TO NEAR GALE FORCE THRU MID MORNING...BUT LACK OF COLD AIR ADVECTION TO ENHANCE MIXING SUGGESTS POTENTIAL IS VERY MINIMAL. OVER THE W...WINDS WILL DIMINISH TO 5-15KT TODAY AS HIGH PRES RIDGE ARRIVES. PRES GRADIENT RELAXES ACROSS THE ENTIRE LAKE WED NIGHT INTO THU AS A TROF MOVES INTO THE UPPER LAKES. OVER THE NEXT 5 DAYS...THE LIGHTEST WINDS WILL OCCUR DURING THIS TIME PERIOD. IN THE WAKE OF THE TROF FRI/SAT...NWRLY WINDS WILL INCREASE INTO THE 15-30KT RANGE WITH THE STRONGEST WINDS AGAIN OVER THE E HALF OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...MZ MARINE...ROLFSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 650 AM EST TUE NOV 25 2008 UPDATED AVIATION DISCUSSION FOR 12Z TAF ISSUANCE .SYNOPSIS... ISSUED AT 419 AM EST 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWS RIDGING COVERING MUCH OF THE WESTERN HALF OF THE U.S. AND IMMEDIATELY ALONG THE EAST COAST...WITH A TROUGH IN-BETWEEN OVER THE WESTERN GREAT LAKES WHICH CONTAINS AN UPPER LOW NEAR DETROIT. COLDEST AIR OF THE UPPER TROUGH REMAINS ON THE WEST SIDE PER 00Z RAOB ANALYSIS OF 850MB TEMPS...WITH READINGS OF -14C AT INL AND -11C AT MPX. FARTHER EAST ACROSS THE TROUGH...TEMPS WARM TO -9C AT CWPL AND GRB AND TO -5C AT APX. THE TROUGH IS ALSO FAIRLY MOIST...AT LEAST IN THE LOW LEVELS AS LATEST 11-3.9 UM IMAGERY AND SFC OBS SHOWS LOW CLOUDS COVERING MUCH OF ONTARIO...EASTERN LAKE SUPERIOR AND ALL OF MI. CWPL SOUNDING REFLECTS THIS BY SATURATION FROM THE SFC TO 850MB. THIS MOISTURE... COMBINED WITH THE COOL AIR AND A BLUSTERY NORTHERLY FLOW ON SUPERIOR HAVE GENERATED SOME LAKE ENHANCED SNOW SHOWERS...HOWEVER MUCH OF THESE HAVE DIMINISHED AS OF 08Z. SYNOPTIC SNOW...ASSOCIATED WITH THE COLD CONVEYOR BELT AROUND A 1001MB SFC LOW IN SRN LAKE HURON...IS MOSTLY CONFINED TO LOWER MI. TO THE WEST...A SFC RIDGE EXTENDS FROM MN INTO NW ONTARIO...WHICH IS LOCATED JUST TO THE EAST OF AN UPPER RIDGE AXIS IN EASTERN MANITOBA. 00Z BIS SOUNDING SHOWS THE DRY AIR ASSOCIATED WITH THE SFC RIDGE...WITH DEWPOINT DEPRESSIONS OF 40C OR GREATER BTWN 700-850MB. THIS DRY AIR HAS BEEN MAKING IT INTO THE CWA...NOTED BY MOSTLY CLEAR SKIES OVER THE NW HALF OF WESTERN LAKE SUPERIOR AND LOWERING DEWPOINTS OVER THE CWA (26F NOW AT STDM4 AND 28 AT P53). THIS DRIER AIR MAY HAVE BEEN THE CAUSE OF THE END OF THE LAKE ENHANCED PCPN...IN ADDITION TO THE FACT THAT THE AIRMASS IS NOT THAT COLD TO BEGIN WITH AS NOTED BY THE 00Z APX 850MB TEMP. WEST OF THE AFOREMENTIONED UPPER RIDGE AXIS IS A SHRTWV TROUGH CROSSING SASKATCHEWAN. && .DISCUSSION... ISSUED AT 419 AM EST MAIN FORECAST CONCERN IS PCPN CHANCES THROUGH FRI...GIVEN LATEST RADAR IMAGERY NOT NEARLY AS IMPRESSIVE AS EARLIER EXPECTED. TODAY...UPPER LOW NEAR DETROIT IS PROGGED TO SLIDE EASTWARD INTO PA THIS AFTN AND THEN INTO WRN NEW YORK STATE BY 00Z. WITH THE LOW MOVING FARTHER AWAY FROM HERE...THE RIDGE AXIS TO OUR NW AND THE SFC RIDGE IS ALLOWED TO BUILD INTO WESTERN LAKE SUPERIOR. THEREFORE... DRIER AIR WILL CONTINUE TO ADVECT INTO THE CWA. GIVEN THE FACT THAT LITTLE PCPN IS OCCURRING ON RADAR AT THE MOMENT AND FURTHER DRY AIR ENTERING THE CWA...HAVE DRIED OUT THE FORECAST FOR TODAY. MODELS HAVE BEEN OVERDOING THE AMOUNT OF LAKE ENHANCEMENT FROM THIS EVENT...AND EVEN THE LATEST 06Z RUNS CONTINUE TO DO SO...BUT TRENDS FROM THE MODELS ARE SHOWING LESS QPF. STILL HAVE MAINTAINED A DECENT AMOUNT OF CLOUD COVER FOR TODAY...PARTICULARLY IN THE NORTH CENTRAL AND EASTERN CWA FROM MOISTURE TRAPPED UNDER A LOWERING INVERSION. OVER THE WEST AND SOUTH CENTRAL...SOME OF THE LAKE EFFECT COULD CLEAR OUT...BUT MID/HIGH CLOUDS ASSOCIATED WITH THE SHRTWV IN SASKATCHEWAN ARE EXPECTED TO DROPPING IN DURING THE AFTN. COLDER 850MB AIR IN OVER THE CWA AND CLOUD COVER SHOULD LIMIT THE AMOUNT OF HEATING TODAY. READINGS WILL END UP A FEW DEGREES COOLER THAN YESTERDAY. TONIGHT...SHRTWV CURRENTLY OVER SASKATCHEWAN IS PROGGED TO DROP SOUTH INTO WESTERN LAKE SUPERIOR BY 12Z WED AS IT DIGS INTO THE UPPER TROUGH OVER THE EASTERN GREAT LAKES. IMPACTS FROM THIS SHRTWV SHOULD BE MOSTLY THE MID/HIGH CLOUDS AHEAD OF IT...SINCE DRY AIR ASSOCIATED WITH THE SFC RIDGE REMAINS IN PLACE OVER WESTERN LAKE SUPERIOR. TO THE EAST...THE UPPER LOW OVER WRN NEW YORK STATE LIFTS TO THE NW IN RESPONSE TO STRONG RIDGING BUILT AHEAD OF IT IN THE CANADIAN MARITIMES. THE UPPER LOW IS A BIT TOO FAR EAST TO HAVE MUCH IMPACT OVER THE CWA...BUT A PERSISTENT NORTHERLY LOW LEVEL FLOW WILL BE CONTINUING DOWN EASTERN SUPERIOR. SOUNDINGS FOR ERY DO NOT LOOK THAT FAVORABLE FOR PCPN...WITH ONLY A 1000-3000 FT THICK LAYER OF CLOUD DUE TO THE LOW INVERSION. THEREFORE HAVE LOWERED POPS TO 20 FOR THE EASTERN CWA. WAS TEMPTED TO REMOVE POPS ENTIRELY GIVEN LACKLUSTER PERFORMANCE OF PCPN CURRENTLY...BUT THE DROP FROM 50 IS TOO MUCH FOR ONE FORECAST. NEEDLESS TO SAY THERE SHOULD STILL BE PLENTY OF CLOUD COVER BETWEEN THE MID/HIGH CLOUDS AND THE TRAPPED LOW LEVEL MOISTURE. THESE CLOUDS WILL HELP HOLD TEMPS UP... ESPECIALLY IN THE EASTERN CWA WHERE THE NORTH FLOW CONTINUES TO BRING WARMER AIR IN OFF EASTERN SUPERIOR. COLDEST READINGS EXPECTED IN GOGEBIC AND IRON COUNTIES...WHERE A PERIOD OF CLEARING IS POSSIBLE AFTER THE MID CLOUDS EXIT LATE TONIGHT. READINGS THERE COULD DROP INTO THE UPPER TEENS AS SUGGESTED BY MET/MAV GUIDANCE. WEDNESDAY...UPPER LOW IN FAR SE ONTARIO LIFTS A BIT FARTHER TO THE NW...BUT STILL WELL AWAY FROM HERE. SHRTWVS ROTATING AROUND THE LOW ARE ALSO FAR ENOUGH AWAY FROM HERE COMPARED TO WHAT IT LOOKED LIKE YESTERDAY SUCH THAT NO SYNOPTIC PCPN IS EXPECTED. PERHAPS SOME SNOW GETS INTO THE WAWA ONTARIO AREA LATER IN THE AFTN AS THE 00Z NAM SUGGESTS...BUT THAT WOULD BE IT FOR THE WESTWARD EXTENT OF THE SYNOPTIC SNOW. MODELS ALSO SHOW SOME LIGHT PCPN COMING OFF EASTERN LAKE SUPERIOR...SIMILAR TO TONIGHT...WITH COLD ENOUGH AIR TO GENERATE LAKE ENHANCED OR LAKE EFFECT PRECIPITATION. HAVE DECIDED TO KEEP SOME 20 POPS IN THE FORECAST FOR THE EASTERN CWA...BUT AGAIN COULD SEE IT BEING DRY AS WELL SEEING WHAT IS HAPPENING RIGHT NOW. ALSO...DO NOT WANT HAVE A HUGE DROP IN POPS FROM THE PREVIOUS FORECAST. THE REST OF THE CWA WILL CONTINUE TO BE UNDER THE INFLUENCE OF THE RIDGE OF HIGH PRESSURE STUCK IN THE MN/WESTERN LAKE SUPERIOR AREA...MAINTAINING DRY WEATHER. A BIT MORE SUN COULD OCCUR AS WELL...ESPECIALLY ALONG THE WI BORDER AWAY FROM LAKE MOISTURE TRAPPED UNDER THE INVERSION. WITH 850MB TEMPS PROGGED FROM -4C WEST TO -8C CENTRAL/EAST AND MORE SUN...HIGHS SHOULD GENERALLY BE IN THE MID 30S...WARMEST SOUTH CENTRAL WITH DOWNSLOPING NW FLOW. WED NIGHT...UPPER LOW IS PROGGED TO LIFT FARTHER NORTH...WHILE TO THE WEST A FAIRLY STRONG SHRTWV IS SHOWN TO DROP DOWN INTO EASTERN NORTH DAKOTA. THE 00Z GFS/ECMWF/UKMET KEEP THE SHRTWVS ROTATING AROUND THE UPPER LOW FARTHER TO THE WEST THAN THE 00Z NAM...AND HAVE DECIDED TO FOLLOW THE MAJORITY. THIS IS REINFORCED BY THE FACT THAT THE SHRTWV TROUGH DROPPING DOWN INTO EASTERN NORTH DAKOTA SHOULD PUSH RIDGING TOWARDS UPPER MI...NOT ALLOWING THE UPPER LOW TO RETREAT WESTWARD. SO IT COMES DOWN TO LAKE EFFECT/ENHANCED PCPN AGAIN...WITH 20 POPS CONFINED TO THE EASTERN CWA. THE WEST AND CENTRAL AREAS CONTINUE TO BE DOMINATED BY THE SFC RIDGE...WHICH GETS A PUSH EASTWARD THROUGH THE NIGHT AS UPPER RIDGING FORMS AHEAD OF THE SHRTWV. THIS MEANS THAT THE WEST AND CENTRAL REMAIN DRY WITH SOME CLOUDS AROUND OFF LAKE SUPERIOR. SHOULD THESE CLOUDS NOT EXIST...WILL NEED TO WATCH TEMPS INLAND...ESPECIALLY WITH THE SFC RIDGE BUILDING IN. HAVE CONTINUED MENTION OF UPPER TEENS INLAND WITH 20S ELSEWHERE...BUT IF SKIES CLEAR THEN LOW TEENS AS SUGGESTED BY MEX COOP GUIDANCE WOULD BE MORE REALISTIC. THU THROUGH FRI...THIS PERIOD OF THE FORECAST IS DOMINATED BY THAT SHRTWV TROUGH THAT DROPPED DOWN INTO EASTERN NORTH DAKOTA. ALREADY THIS TROUGH IS FASTER COMPARED TO WHAT THE 00Z RUNS FROM YESTERDAY SHOWED. MODELS DISAGREE ON THE SPEED OF THE TROUGH...WITH THE ECMWF AND UKMET FASTER COMPARED WITH THE GFS/NAM. HPC PREFERENCE WAS TO FOLLOW THE FASTER SCENARIO...WHICH MAKES SENSE GIVEN THE FASTER MOTION TO BEGIN WITH. THIS TROUGH SHOULD CROSS INTO CENTRAL WI BY 00Z FRI...THEN HEAD INTO THE EASTERN GREAT LAKES BY 12Z FRI. SINCE THE TROUGH IS GOING JUST TO OUR SOUTH...THE TRACK IS FAVORABLE FOR A FRONTOGENETICAL BAND OF SNOW TO MOVE ACROSS THE CWA. BEST GUESS TIMING FOR THE BAND WOULD BE BTWN 18Z AND 06Z. INCLUDED POPS IN THE FORECAST...GENERALLY 30-50 FOR NOW...BUT IF TRENDS CONTINUE MORE INCREASES WILL BE NEEDED. SINCE THE TROUGH IS A FAST MOVER AND DOES NOT HAVE A LOT OF MOISTURE TO WORK WITH...SINCE IT IS COMING OUT OF CENTRAL CANADA INSTEAD OF THE SRN PLAINS...ONLY LIGHT ACCUMULATIONS OF SNOW ARE EXPECTED. IN THE WAKE OF THE SHRTWV...COOLER AIR FILTERS FOR LATER THU NIGHT INTO FRI...WITH 850MB TEMPS DROPPING TO AROUND -10C. THEREFORE...SOME LAKE EFFECT SHOULD START UP...MOSTLY AFFECTING THE NW FLOW SNOWBELTS. HIGHS ON THU WILL BE SLIGHTLY COOLER THAN WED SINCE CLOUDS ARE EXPECTED TO RAPIDLY APPROACH WITH THE TROUGH. LOOK FOR FRI TO BE A LITTLE COOLER TOO AS THE COLD ADVECTION STARTS UP. NO CHANGES MADE BEYOND FRI. LOOKS LIKE A GENERAL LAKE EFFECT PATTERN INTO THE WEEKEND WITH GENERAL TROUGHING SETTING UP OVER THE GREAT LAKES AND 850MB TEMPS IN THE -10 TO -12C RANGE. MEAN WIND DIRECTION LOOKS TO BE NW...SO NW FLOW SNOWBELTS WOULD HAVE THE BETTER CHANCE FOR LAKE EFFECT. HIGHS AND LOWS EXPECTED TO STAY AROUND NORMAL GIVEN THE 850MB READINGS. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... OVERALL...EXPECT MVFR CIGS TO PREVAIL AT KCMX/KSAW THRU THIS FCST PERIOD AS LOW-LEVEL MOISTURE REMAINS TRAPPED BELOW A SLIGHTLY LOWERING INVERSION. SOME -SHSN ARE CURRENTLY MOVING ONSHORE IN NCNTRL UPPER MI...AND THOSE WILL LIKELY REACH KSAW AT TIMES THRU THE MORNING. VIS SHOULD REMAIN VFR WITH ANY -SHSN THOUGH CAN`T RULE OUT BRIEF REDUCTION TO MVFR. CLOUDS MAY OCCASIONALLY SCATTER OUT AT KCMX...BUT IT APPEARS LOW-LEVEL MOISTURE WILL REMAIN SUFFICIENT THAT BKN MVFR CIGS SHOULD BE THE RULE THRU THE FCST PERIOD. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRES JUST E OF LAKE HURON WILL MEANDER E ACROSS THE LOWER GREAT LAKES REGION THRU WED. AS THIS OCCURS...NRLY WINDS WILL GRADUALLY DECREASE TODAY AND TONIGHT. OVER ERN LAKE SUPERIOR...EXPECT 20-30KT WINDS TO DECREASE TO 15-25KT THIS AFTN AND TO 10-20KT TONIGHT. THERE MAY BE A FEW GUSTS TO NEAR GALE FORCE THRU MID MORNING...BUT LACK OF COLD AIR ADVECTION TO ENHANCE MIXING SUGGESTS POTENTIAL IS VERY MINIMAL. OVER THE W...WINDS WILL DIMINISH TO 5-15KT TODAY AS HIGH PRES RIDGE ARRIVES. PRES GRADIENT RELAXES ACROSS THE ENTIRE LAKE WED NIGHT INTO THU AS A TROF MOVES INTO THE UPPER LAKES. OVER THE NEXT 5 DAYS...THE LIGHTEST WINDS WILL OCCUR DURING THIS TIME PERIOD. IN THE WAKE OF THE TROF FRI/SAT...NWRLY WINDS WILL INCREASE INTO THE 15-30KT RANGE WITH THE STRONGEST WINDS AGAIN OVER THE E HALF OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 419 AM EST TUE NOV 25 2008 .SYNOPSIS... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWS RIDGING COVERING MUCH OF THE WESTERN HALF OF THE U.S. AND IMMEDIATELY ALONG THE EAST COAST...WITH A TROUGH IN-BETWEEN OVER THE WESTERN GREAT LAKES WHICH CONTAINS AN UPPER LOW NEAR DETROIT. COLDEST AIR OF THE UPPER TROUGH REMAINS ON THE WEST SIDE PER 00Z RAOB ANALYSIS OF 850MB TEMPS...WITH READINGS OF -14C AT INL AND -11C AT MPX. FARTHER EAST ACROSS THE TROUGH...TEMPS WARM TO -9C AT CWPL AND GRB AND TO -5C AT APX. THE TROUGH IS ALSO FAIRLY MOIST...AT LEAST IN THE LOW LEVELS AS LATEST 11-3.9 UM IMAGERY AND SFC OBS SHOWS LOW CLOUDS COVERING MUCH OF ONTARIO...EASTERN LAKE SUPERIOR AND ALL OF MI. CWPL SOUNDING REFLECTS THIS BY SATURATION FROM THE SFC TO 850MB. THIS MOISTURE... COMBINED WITH THE COOL AIR AND A BLUSTERY NORTHERLY FLOW ON SUPERIOR HAVE GENERATED SOME LAKE ENHANCED SNOW SHOWERS...HOWEVER MUCH OF THESE HAVE DIMINISHED AS OF 08Z. SYNOPTIC SNOW...ASSOCIATED WITH THE COLD CONVEYOR BELT AROUND A 1001MB SFC LOW IN SRN LAKE HURON...IS MOSTLY CONFINED TO LOWER MI. TO THE WEST...A SFC RIDGE EXTENDS FROM MN INTO NW ONTARIO...WHICH IS LOCATED JUST TO THE EAST OF AN UPPER RIDGE AXIS IN EASTERN MANITOBA. 00Z BIS SOUNDING SHOWS THE DRY AIR ASSOCIATED WITH THE SFC RIDGE...WITH DEWPOINT DEPRESSIONS OF 40C OR GREATER BTWN 700-850MB. THIS DRY AIR HAS BEEN MAKING IT INTO THE CWA...NOTED BY MOSTLY CLEAR SKIES OVER THE NW HALF OF WESTERN LAKE SUPERIOR AND LOWERING DEWPOINTS OVER THE CWA (26F NOW AT STDM4 AND 28 AT P53). THIS DRIER AIR MAY HAVE BEEN THE CAUSE OF THE END OF THE LAKE ENHANCED PCPN...IN ADDITION TO THE FACT THAT THE AIRMASS IS NOT THAT COLD TO BEGIN WITH AS NOTED BY THE 00Z APX 850MB TEMP. WEST OF THE AFOREMENTIONED UPPER RIDGE AXIS IS A SHRTWV TROUGH CROSSING SASKATCHEWAN. && .DISCUSSION... MAIN FORECAST CONCERN IS PCPN CHANCES THROUGH FRI...GIVEN LATEST RADAR IMAGERY NOT NEARLY AS IMPRESSIVE AS EARLIER EXPECTED. TODAY...UPPER LOW NEAR DETROIT IS PROGGED TO SLIDE EASTWARD INTO PA THIS AFTN AND THEN INTO WRN NEW YORK STATE BY 00Z. WITH THE LOW MOVING FARTHER AWAY FROM HERE...THE RIDGE AXIS TO OUR NW AND THE SFC RIDGE IS ALLOWED TO BUILD INTO WESTERN LAKE SUPERIOR. THEREFORE... DRIER AIR WILL CONTINUE TO ADVECT INTO THE CWA. GIVEN THE FACT THAT LITTLE PCPN IS OCCURRING ON RADAR AT THE MOMENT AND FURTHER DRY AIR ENTERING THE CWA...HAVE DRIED OUT THE FORECAST FOR TODAY. MODELS HAVE BEEN OVERDOING THE AMOUNT OF LAKE ENHANCEMENT FROM THIS EVENT...AND EVEN THE LATEST 06Z RUNS CONTINUE TO DO SO...BUT TRENDS FROM THE MODELS ARE SHOWING LESS QPF. STILL HAVE MAINTAINED A DECENT AMOUNT OF CLOUD COVER FOR TODAY...PARTICULARLY IN THE NORTH CENTRAL AND EASTERN CWA FROM MOISTURE TRAPPED UNDER A LOWERING INVERSION. OVER THE WEST AND SOUTH CENTRAL...SOME OF THE LAKE EFFECT COULD CLEAR OUT...BUT MID/HIGH CLOUDS ASSOCIATED WITH THE SHRTWV IN SASKATCHEWAN ARE EXPECTED TO DROPPING IN DURING THE AFTN. COLDER 850MB AIR IN OVER THE CWA AND CLOUD COVER SHOULD LIMIT THE AMOUNT OF HEATING TODAY. READINGS WILL END UP A FEW DEGREES COOLER THAN YESTERDAY. TONIGHT...SHRTWV CURRENTLY OVER SASKATCHEWAN IS PROGGED TO DROP SOUTH INTO WESTERN LAKE SUPERIOR BY 12Z WED AS IT DIGS INTO THE UPPER TROUGH OVER THE EASTERN GREAT LAKES. IMPACTS FROM THIS SHRTWV SHOULD BE MOSTLY THE MID/HIGH CLOUDS AHEAD OF IT...SINCE DRY AIR ASSOCIATED WITH THE SFC RIDGE REMAINS IN PLACE OVER WESTERN LAKE SUPERIOR. TO THE EAST...THE UPPER LOW OVER WRN NEW YORK STATE LIFTS TO THE NW IN RESPONSE TO STRONG RIDGING BUILT AHEAD OF IT IN THE CANADIAN MARITIMES. THE UPPER LOW IS A BIT TOO FAR EAST TO HAVE MUCH IMPACT OVER THE CWA...BUT A PERSISTENT NORTHERLY LOW LEVEL FLOW WILL BE CONTINUING DOWN EASTERN SUPERIOR. SOUNDINGS FOR ERY DO NOT LOOK THAT FAVORABLE FOR PCPN...WITH ONLY A 1000-3000 FT THICK LAYER OF CLOUD DUE TO THE LOW INVERSION. THEREFORE HAVE LOWERED POPS TO 20 FOR THE EASTERN CWA. WAS TEMPTED TO REMOVE POPS ENTIRELY GIVEN LACKLUSTER PERFORMANCE OF PCPN CURRENTLY...BUT THE DROP FROM 50 IS TOO MUCH FOR ONE FORECAST. NEEDLESS TO SAY THERE SHOULD STILL BE PLENTY OF CLOUD COVER BETWEEN THE MID/HIGH CLOUDS AND THE TRAPPED LOW LEVEL MOISTURE. THESE CLOUDS WILL HELP HOLD TEMPS UP... ESPECIALLY IN THE EASTERN CWA WHERE THE NORTH FLOW CONTINUES TO BRING WARMER AIR IN OFF EASTERN SUPERIOR. COLDEST READINGS EXPECTED IN GOGEBIC AND IRON COUNTIES...WHERE A PERIOD OF CLEARING IS POSSIBLE AFTER THE MID CLOUDS EXIT LATE TONIGHT. READINGS THERE COULD DROP INTO THE UPPER TEENS AS SUGGESTED BY MET/MAV GUIDANCE. WEDNESDAY...UPPER LOW IN FAR SE ONTARIO LIFTS A BIT FARTHER TO THE NW...BUT STILL WELL AWAY FROM HERE. SHRTWVS ROTATING AROUND THE LOW ARE ALSO FAR ENOUGH AWAY FROM HERE COMPARED TO WHAT IT LOOKED LIKE YESTERDAY SUCH THAT NO SYNOPTIC PCPN IS EXPECTED. PERHAPS SOME SNOW GETS INTO THE WAWA ONTARIO AREA LATER IN THE AFTN AS THE 00Z NAM SUGGESTS...BUT THAT WOULD BE IT FOR THE WESTWARD EXTENT OF THE SYNOPTIC SNOW. MODELS ALSO SHOW SOME LIGHT PCPN COMING OFF EASTERN LAKE SUPERIOR...SIMILAR TO TONIGHT...WITH COLD ENOUGH AIR TO GENERATE LAKE ENHANCED OR LAKE EFFECT PRECIPITATION. HAVE DECIDED TO KEEP SOME 20 POPS IN THE FORECAST FOR THE EASTERN CWA...BUT AGAIN COULD SEE IT BEING DRY AS WELL SEEING WHAT IS HAPPENING RIGHT NOW. ALSO...DO NOT WANT HAVE A HUGE DROP IN POPS FROM THE PREVIOUS FORECAST. THE REST OF THE CWA WILL CONTINUE TO BE UNDER THE INFLUENCE OF THE RIDGE OF HIGH PRESSURE STUCK IN THE MN/WESTERN LAKE SUPERIOR AREA...MAINTAINING DRY WEATHER. A BIT MORE SUN COULD OCCUR AS WELL...ESPECIALLY ALONG THE WI BORDER AWAY FROM LAKE MOISTURE TRAPPED UNDER THE INVERSION. WITH 850MB TEMPS PROGGED FROM -4C WEST TO -8C CENTRAL/EAST AND MORE SUN...HIGHS SHOULD GENERALLY BE IN THE MID 30S...WARMEST SOUTH CENTRAL WITH DOWNSLOPING NW FLOW. WED NIGHT...UPPER LOW IS PROGGED TO LIFT FARTHER NORTH...WHILE TO THE WEST A FAIRLY STRONG SHRTWV IS SHOWN TO DROP DOWN INTO EASTERN NORTH DAKOTA. THE 00Z GFS/ECMWF/UKMET KEEP THE SHRTWVS ROTATING AROUND THE UPPER LOW FARTHER TO THE WEST THAN THE 00Z NAM...AND HAVE DECIDED TO FOLLOW THE MAJORITY. THIS IS REINFORCED BY THE FACT THAT THE SHRTWV TROUGH DROPPING DOWN INTO EASTERN NORTH DAKOTA SHOULD PUSH RIDGING TOWARDS UPPER MI...NOT ALLOWING THE UPPER LOW TO RETREAT WESTWARD. SO IT COMES DOWN TO LAKE EFFECT/ENHANCED PCPN AGAIN...WITH 20 POPS CONFINED TO THE EASTERN CWA. THE WEST AND CENTRAL AREAS CONTINUE TO BE DOMINATED BY THE SFC RIDGE...WHICH GETS A PUSH EASTWARD THROUGH THE NIGHT AS UPPER RIDGING FORMS AHEAD OF THE SHRTWV. THIS MEANS THAT THE WEST AND CENTRAL REMAIN DRY WITH SOME CLOUDS AROUND OFF LAKE SUPERIOR. SHOULD THESE CLOUDS NOT EXIST...WILL NEED TO WATCH TEMPS INLAND...ESPECIALLY WITH THE SFC RIDGE BUILDING IN. HAVE CONTINUED MENTION OF UPPER TEENS INLAND WITH 20S ELSEWHERE...BUT IF SKIES CLEAR THEN LOW TEENS AS SUGGESTED BY MEX COOP GUIDANCE WOULD BE MORE REALISTIC. THU THROUGH FRI...THIS PERIOD OF THE FORECAST IS DOMINATED BY THAT SHRTWV TROUGH THAT DROPPED DOWN INTO EASTERN NORTH DAKOTA. ALREADY THIS TROUGH IS FASTER COMPARED TO WHAT THE 00Z RUNS FROM YESTERDAY SHOWED. MODELS DISAGREE ON THE SPEED OF THE TROUGH...WITH THE ECMWF AND UKMET FASTER COMPARED WITH THE GFS/NAM. HPC PREFERENCE WAS TO FOLLOW THE FASTER SCENARIO...WHICH MAKES SENSE GIVEN THE FASTER MOTION TO BEGIN WITH. THIS TROUGH SHOULD CROSS INTO CENTRAL WI BY 00Z FRI...THEN HEAD INTO THE EASTERN GREAT LAKES BY 12Z FRI. SINCE THE TROUGH IS GOING JUST TO OUR SOUTH...THE TRACK IS FAVORABLE FOR A FRONTOGENETICAL BAND OF SNOW TO MOVE ACROSS THE CWA. BEST GUESS TIMING FOR THE BAND WOULD BE BTWN 18Z AND 06Z. INCLUDED POPS IN THE FORECAST...GENERALLY 30-50 FOR NOW...BUT IF TRENDS CONTINUE MORE INCREASES WILL BE NEEDED. SINCE THE TROUGH IS A FAST MOVER AND DOES NOT HAVE A LOT OF MOISTURE TO WORK WITH...SINCE IT IS COMING OUT OF CENTRAL CANADA INSTEAD OF THE SRN PLAINS...ONLY LIGHT ACCUMULATIONS OF SNOW ARE EXPECTED. IN THE WAKE OF THE SHRTWV...COOLER AIR FILTERS FOR LATER THU NIGHT INTO FRI...WITH 850MB TEMPS DROPPING TO AROUND -10C. THEREFORE...SOME LAKE EFFECT SHOULD START UP...MOSTLY AFFECTING THE NW FLOW SNOWBELTS. HIGHS ON THU WILL BE SLIGHTLY COOLER THAN WED SINCE CLOUDS ARE EXPECTED TO RAPIDLY APPROACH WITH THE TROUGH. LOOK FOR FRI TO BE A LITTLE COOLER TOO AS THE COLD ADVECTION STARTS UP. NO CHANGES MADE BEYOND FRI. LOOKS LIKE A GENERAL LAKE EFFECT PATTERN INTO THE WEEKEND WITH GENERAL TROUGHING SETTING UP OVER THE GREAT LAKES AND 850MB TEMPS IN THE -10 TO -12C RANGE. MEAN WIND DIRECTION LOOKS TO BE NW...SO NW FLOW SNOWBELTS WOULD HAVE THE BETTER CHANCE FOR LAKE EFFECT. HIGHS AND LOWS EXPECTED TO STAY AROUND NORMAL GIVEN THE 850MB READINGS. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... OVERALL...EXPECT MVFR CIGS TO PREVAIL AT KCMX/KSAW THRU THIS FCST PERIOD. SOME LIGHT LAKE ENHANCED SNOW IS EXPECTED...ESPECIALLY AT KSAW WITH CONVERGENT NRLY UPSLOPING FLOW. THE LACK OF SIGNIFICANT COLD AIR SHOULD LIMIT INTENSITY WITH ONLY MINOR VSBY REDUCTION INTO THE MVFR RANGE. LOW LEVEL MOISTURE TRAPPED UNDER INVERSION WILL KEEP MVFR CIGS AT BOTH KCMX AND KSAW THROUGH TUESDAY. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRES JUST E OF LAKE HURON WILL MEANDER E ACROSS THE LOWER GREAT LAKES REGION THRU WED. AS THIS OCCURS...NRLY WINDS WILL GRADUALLY DECREASE TODAY AND TONIGHT. OVER ERN LAKE SUPERIOR...EXPECT 20-30KT WINDS TO DECREASE TO 15-25KT THIS AFTN AND TO 10-20KT TONIGHT. THERE MAY BE A FEW GUSTS TO NEAR GALE FORCE THRU MID MORNING...BUT LACK OF COLD AIR ADVECTION TO ENHANCE MIXING SUGGESTS POTENTIAL IS VERY MINIMAL. OVER THE W...WINDS WILL DIMINISH TO 5-15KT TODAY AS HIGH PRES RIDGE ARRIVES. PRES GRADIENT RELAXES ACROSS THE ENTIRE LAKE WED NIGHT INTO THU AS A TROF MOVES INTO THE UPPER LAKES. OVER THE NEXT 5 DAYS...THE LIGHTEST WINDS WILL OCCUR DURING THIS TIME PERIOD. IN THE WAKE OF THE TROF FRI/SAT...NWRLY WINDS WILL INCREASE INTO THE 15-30KT RANGE WITH THE STRONGEST WINDS AGAIN OVER THE E HALF OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...JLB MARINE...ROLFSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 120 PM EST MON NOV 24 2008 UPDATED FOR 18Z TAF ISSUANCE .UPDATE... UPPER LOW CONTINUES TO DROP SOUTHEASTWARD OUT OF WESTERN ONTARIO TOWARDS WESTERN LAKE SUPERIOR THIS MORNING. EVENTUALLY UPPER LOW WILL MERGE WITH S/WV OVER SOUTHERN LAKE MI FORMING BROADER UPPER LOW OVER SOUTHERN GREAT LAKES. WEAK SFC LOW CURRENTLY OVER SOUTHERN LOWER MI WILL MOVE SLOWLY EWD TO SOUTHERN LAKE HURON BY THE END OF THE DAY. BACK EDGE OF LIGHT SNOW FIELD ASSOCIATED WITH THESE FEATURES HAS MOVED INTO LAKE MI. BEST CHANCE FOR LIGHT SNOW THIS AFTERNOON WILL BE EAST OF A MANISTIQUE TO NEWBERRY LINE AND EVEN THERE AMOUNTS SHOULD BE LIGHT. AS MAIN UPPER LOW DROPS SOUTHEASTWARD ACROSS FAR WESTERN LAKE SUPERIOR EXPECT FLURRIES/-SHSN TO ACCOMPANY IT. WITH A SLIGHTLY WESTWARD UPPER LOW TRACK EXPECT BEST CHANCE OF THIS ACTIVITY ACROSS WESTERN UPPER MICHIGAN WITH CENTRAL AREAS REMAINING PRECIP FREE THROUGH MUCH OF THE DAY. 85H TEMPS WILL FALL INTO THE -8 TO -10 RANGE OVER WESTERN LAKE SUPERIOR AND AS WINDS BECOME MORE NORTHWESTERLY DO EXPECT SOME LAKE ENHANCEMENT TO OCCUR IN FAVORABLE UPSLOPE AREAS IN THE WEST. STILL NOT EXPECTING ANYTHING MORE THAN AN INCH OR AT MOST 2 OF ACCUMULATION DURING THE DAY TODAY. OVERALL TEMP FORECAST IS ON TRACK AND WILL NOT MAKE ANY ADJUSTMENTS TO IT. .SYNOPSIS... ISSUED AT 425 AM EST 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING OVER THE WESTERN U.S. INTO SW CANADA...RIDGING IN THE OHIO VALLEY INTO THE EASTERN GREAT LAKES...AND A TROUGH FROM MANITOBA SOUTHWARD INTO THE CENTRAL PLAINS. WITHIN THE TROUGH...AN UPPER LOW IS LOCATED AT THE FAR NORTH END OF LAKE WINNIPEG. THE WARM CONVEYOR BELT AHEAD OF THE UPPER LOW EXTENDS FROM MO ACROSS UPPER MI AND INTO NE ONTARIO. SOME -SN IS FALLING OUT OF THE CONVEYOR BELT OVER THE CENTRAL PORTION OF THE CWA...ALSO IN THE SAME PLACE WHERE BETTER MOISTURE IS BASED ON 00Z RAOBS FROM MPX...COMPARED TO GRB AND APX WHICH REFLECT THE DRIER AIRMASS OVER EASTERN UPPER MI. A DRY SLOT IS EVIDENT ON 11-3.9 U IMAGERY OVER NE MN...BUT FARTHER NW OVER NW MN INTO MANITOBA IS THE COLD CONVEYOR BELT (CCB) CLOUDS ON THE BACK SIDE OF THE UPPER LOW. 850MB TEMPS UNDER THE CCB WERE AROUND -14C BASED ON THE 00Z SOUNDING FROM CYQD...QUITE A BIT COLDER THAN THE -1C AT MPX...-4C AT INL AND -6C AT CWPL. TO THE SW OF UPPER MI ON WATER VAPOR...A SHRTWV IS MOVING THROUGH SRN IA. ASSOCIATED WITH THE SHRTWV IS A 1015MB SFC LOW IN SE IA. A TROUGH EXTENDS NE FROM THE LOW ACROSS CENTRAL UPPER MI...THEN HEADS BACK TO THE NW AS A COLD FRONT WHERE IT CONNECTS UP TO A 1008MB LOW IN FAR NW ONTARIO. && .DISCUSSION... ISSUED AT 425 AM EST MAIN FORECAST CONCERNS ARE THE AMOUNT OF SNOW THE NEXT TWO DAYS... ALONG WITH POTENTIAL FOR FREEZING DRIZZLE. TODAY...UPPER LOW AT THE NORTH END OF LAKE WINNIPEG IS PROGGED TO SLIDE A LITTLE BIT FARTHER WEST COMPARED TO YESTERDAYS 00Z RUNS...MOVING INTO WRN WI AT 00Z TUE. THE BULK OF THE COLD AIR SEEN UPSTREAM AT CYQD WILL STAY UNDER OR TO THE WEST OF THE UPPER LOW. HOWEVER...SOME COOLING IS STILL EXPECTED TO COME INTO UPPER MICHIGAN WITH THE APPROACH OF THE UPPER LOW. NAM/GFS SHOW 850MB TEMPS FALLING TO -8 TO -10C OVER WRN LAKE SUPERIOR...WHICH WOULD BE GOOD ENOUGH FOR LAKE ENHANCED OR PERHAPS EVEN PURE LAKE EFFECT. WITH NW WINDS... IT WOULD SEEM LIKELY FOR SNOW IN WRN UPPER MI...ESPECIALLY IN UPSLOPE AREAS. HAVE RAISED POPS TO DEFINITE IN THE UPSLOPE AREA FROM IWD TO ROCKLAND. SOUNDINGS SUGGEST SNOW TO WATER RATIOS SOMEWHERE AROUND 10 TO 1...DUE TO MAJORITY OF VERTICAL MOTION BELOW THE DENDRITIC SNOW GROWTH ZONE...WHICH WITH A BLEND OF NAM/LOCAL WRF-ARW RUN/GFS FOR QPF RESULTS IN 1 TO 2 INCHES. THE AMOUNT OF COLD AIR CROSSING CENTRAL AND LAKE SUPERIOR IS A LITTLE MORE UNCERTAIN... WITH THE GFS SHOWING -8 TO PERHAPS -10C AT 00Z TUE...COMPARED TO THE NAM AND LOCAL WRF-ARW WHICH HAVE -4 TO -6C. EITHER SCENARIO SEEMS AT LEAST POSSIBLE FOR LAKE ENHANCED PCPN...ESPECIALLY GIVEN THAT THERE WILL BE PLENTY OF MOISTURE AROUND IN THE WARM CONVEYOR BELT AHEAD OF THE UPPER LOW. THE PROBLEM IS THAT THE WARMER SCENARIO WOULD RESULT IN POTENTIAL FOR RAIN TO MIX IN...PARTICULARLY OVER LAKE SUPERIOR AND OVER LAND NEAR THE SUPERIOR SHORELINE. GIVEN 00Z SOUNDING FROM CWPL UPSTREAM WAS -6C...WILL LEAN TOWARDS THE NAM/LOCAL WRF-ARW. THE WARMER SCENARIO ALSO MEANS THAT ANY SNOW THAT FALLS INLAND WILL ALSO BE WETTER WITH SNOW TO WATER RATIOS LESS THAN 10 TO 1. COULD BE AN INCH...PERHAPS TWO OF THIS WET SNOW IN THE EASTERN CWA. THE CENTRAL U.P. LOOKS TO BE MAINLY DRY TODAY...WITH SOME SUN AS THE DRY-SLOT WORKS IN. A FEW -SHSN COULD WORK IN OVER MQT COUNTY OFF OF WRN SUPERIOR IN THE AFTN...BUT THAT IS ABOUT IT FOR CENTRAL UPPER MI. ALTHOUGH COLD AIR IS FLOWING IN...EXPECT HIGHS AGAIN TODAY IN THE 30S...WARMEST SOUTH CENTRAL WITH DOWNSLOPING NW WINDS AND NEAR LAKE SUPERIOR WITH HEAT FLUX OFF THE WARMER WATER. TONIGHT...UPPER LOW MOVES SE INTO OHIO BY 12Z TUE...COMING CLOSE TO PHASING WITH THE SHRTWV CURRENTLY HEADING EAST OUT OF SRN IA. AS A RESULT...THE SFC LOWS THAT ARE CURRENTLY IN NW ONTARIO AND SE IA END UP MERGING TOGETHER INTO A DEEPER 1003 MB LOW NEAR LONDON ONTARIO AT 12Z TUE. THE DEEPENING LOW HELPS TO STRENGTHEN NORTH TO NE WINDS OVER EASTERN LAKE SUPERIOR. NORMALLY THIS WOULD SPELL COLDER AIR MOVING IN. HOWEVER...THE AIR COMING IN IS EITHER JUST AS COOL OR PERHAPS EVEN SLIGHTLY WARMER THAN THE AIR THAT IS IN OVER THE CWA AT 00Z PER 850MB TEMP PROGS. THE REASON IS THAT THE DEEPENING LOW HELPS TO PULL WARMER AIR IN OFF THE ATLANTIC INTO ITS CIRCULATION. SO WITH LITTLE TO NO CHANGE IN 850MB TEMPS...LAKE ENHANCEMENT SHOULD BE THE RULE...POSSIBLY PURE LAKE EFFECT IN THE WRN U.P.. PROBLEM IN THE WRN U.P. COMPARED TO TODAY IS THAT WITH THE DEPARTURE OF THE UPPER LOW...INVERSIONS FALL WITH THE MID-LEVEL HEIGHT RISES. THE QUESTION IS IF THE -10C ISOTHERM DRIES OUT...WHICH WOULD CHANGE THE PCPN FROM SNOW TO FZDZ GIVEN THAT AN UPSLOPING WIND CONTINUES. RIGHT NOW ONLY OUR LOCAL WRF-ARW RUN SHOWS THIS OCCURRING...WHILE THE NAM/GFS SHOW THE -10C ISOTHERM REMAINING MOIST. THEREFORE HAVE DECIDED TO KEEP THE P-TYPE AS SNOW. IN THE CENTRAL AND EAST...INVERSIONS WILL GRADUALLY LOWER AS WELL...BUT NOT AS QUICK. SO CONFIDENCE IS HIGHER THAT THE P-TYPE WILL STAY AS SNOW INLAND FROM LAKE SUPERIOR. AMOUNTS OF SNOW SHOULD NOT BE THAT IMPRESSIVE...MAYBE AN INCH OR TWO GIVEN LOW SNOW TO WATER RATIOS. REGARDING AREAS NEAR THE LAKE...THE WARMER NAM/LOCAL WRF-ARW RUNS SUGGEST HOLDING ON TO A RAIN/SNOW MIX THROUGH AT LEAST 09Z. IF THE PCPN IS GENERALLY LIGHT...THEN MORE OF THE PCPN SHOULD FALL AS RAIN. GIVEN THE WARMER 850MB TEMPS AND PLENTY OF CLOUDS...ALONG WITH A FLOW OF AIR OFF THE WARM LAKE SUPERIOR WATER...TEMPS SHOULD NOT DROP TOO MUCH. COLDEST READINGS EXPECTED IN THE INTERIOR WEST...CLOSEST TO THE COLDEST 850MB AIR...BUT EVEN THESE SHOULD ONLY BE IN THE MID 20S. TUESDAY...UPPER LOW IS PROGGED TO SHIFT INTO NORTH CENTRAL PA BY 00Z WED...WITH THE SFC LOW MOVING TO THE LAKE ONTARIO AREA. THIS ALLOWS A HIGH PRESSURE RIDGE TO BUILD INTO WESTERN UPPER MI BY 00Z...IN ADDITION TO CONTINUED MID-LEVEL HEIGHT RISES THROUGH THE DAY. THE RIDGE SHOULD BRING DRIER AIR IN...LIKELY TO THE WESTERN CWA...ENOUGH TO END PCPN BY EARLY AFTN. HOWEVER...THE CENTRAL AND EASTERN CWA WILL STAY IN LOW CLOUDS TRAPPED UNDER THE LOWERING INVERSION... ENHANCED BY LAKE SUPERIOR GIVEN COOL AIR BELOW THE INVERSION. PCPN TYPE IS VERY TRICKY...AS ALL MODELS SHOW THE -10C LAYER DRYING OUT THROUGH THE DAY. GIVEN A NORTH WIND OVER EASTERN LAKE SUPERIOR...SET UP IS FAVORABLE FOR UPSLOPE. SO WITH LAKE ENHANCEMENT OFF LAKE SUPERIOR AND UPSLOPE FLOW PRODUCING VERTICAL MOTION...SOME PCPN SHOULD OCCUR OUT OF THE CLOUDS. RIGHT NOW HAVE GONE WITH EITHER SNOW SHOWERS OR DZ/FZDZ (FZDZ OVER INLAND AREAS THROUGH THE EARLY AFTN). POPS ARE HIGHEST IN THE UPSLOPE AREAS OF THE NORTH CENTRAL IN THE MORNING...THEN DECREASE IN THE AFTN AS THE DRIER AIR TRIES TO WORK IN. GIVEN CLOUD COVER AND 850MB TEMPS THAT ARE SLIGHTLY COOLER THAN TODAY...HIGHS WILL ALSO END UP SLIGHTLY COOLER. STILL...MOST LOCATIONS SHOULD BE IN THE 30S...WARMEST IN THE DOWNSLOPE AREAS OF THE SOUTH CENTRAL. TUE NIGHT THROUGH THU...PER THE UKMET/NAM/GFS/ECMWF...UPPER MI LOOKS TO BE CAUGHT IN SQUEEZE-PLAY AS THE UPPER LEVEL PATTERN OVER CANADA AND THE NORTHERN U.S. BECOMES BLOCKED. THIS BLOCKING LOOKS TO BE A RESULT OF STRONG RIDGING BUILT UP AHEAD OF THE UPPER LOW TO OUR EAST. IN FACT...MODELS ARE IN GOOD AGREEMENT TAKING THE UPPER LOW BACK TO THE NW DURING THIS PERIOD...BASICALLY PULLED BY THE CURRENT SHRTWV CROSSING SRN IA. WHAT THIS MEANS FOR UPPER MI IS A PERSISTENT CHANCE FOR -SN ACROSS THE EAST HALF OF UPPER MI CLOSER TO THE DEEPER MOISTURE AROUND THE UPPER LOW...WHILE THE WEST HALF OF UPPER MI IS DRY WITH PARTLY CLOUDY SKIES UNDER THE INFLUENCE OF LOW INVERSIONS AND THE SURFACE RIDGE. STILL MAINTAINED THE POSSIBILITY OF SOME DZ/FZDZ OVER THE EASTERN CWA TUE NIGHT SINCE IT DOES NOT APPEAR THAT THE DEEPER MOISTURE WILL MOVE IN UNTIL WED. ANY PCPN LOOKS TO BE LIGHT AT THE CURRENT TIME DUE TO LACK OF SIGNIFICANT MOISTURE WITH THE UPPER LOW. GIVEN THE BLOCKED PATTERN...NO SIGNIFICANT COOLING OR WARMING IS PLANNED. THEREFORE... LOWS AND HIGHS ARE FORECAST TO BE ABOUT THE SAME THROUGH THE PERIOD...IN THE 20S AND 30S RESPECTIVELY. BEYOND THU...NO SIGNIFICANT CHANGES MADE. 00Z ECMWF/GFS/GFS ENSEMBLES ARE ALL IN VERY GOOD AGREEMENT SHOWING THE DEVELOPMENT OF A BROAD TROUGH ACROSS THE GREAT LAKES INTO THE OHIO VALLEY FOR FRI INTO THE WEEKEND. THIS TROUGH IS FORMED BY A COMBINATION OF THE UPPER LOW TO OUR EAST ON THU AND ANOTHER TROUGH DROPPING DOWN OUT OF CENTRAL CANADA. THIS MEANS THAT GRADUAL COOLING WILL OCCUR...COLD ENOUGH TO SET UP PURE LAKE EFFECT BY THE WEEKEND. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... OVERALL...EXPECT MVFR CONDITIONS TO PREVAIL AT KCMX/KSAW THRU THIS FCST PERIOD. UPPER LOW DROPPING ACROSS WESTERN LAKE SUPERIOR WILL BRING SOME -SHSN TO KCMX THIS AFTN AND KSAW THIS EVENING. SOME LAKE ENHANCEMENT IS EXPECTED...ESPECIALLY AT KSAW AS CONVERGENT NRLY UPSLOPING FLOW DEVELOPS. MAY SEE IFR CONDITIONS FOR A TIME LATE EVENING INTO THE OVERNIGHT. LOW LEVEL MOISTURE TRAPPED UNDER INVERSION WILL KEEP MVFR CIGS AT BOTH KCMX AND KSAW THROUGH 18Z TUESDAY. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A LOW PRES TROF EXTENDING FROM NORTHERN ONTARIO ACROSS THE UPPER GREAT LAKES TO THE MID MISSISSIPPI RIVER VALLEY WILL CONSOLIDATE INTO A LOW PRES CENTER OVER SRN LAKE HURON THIS EVENING. AS THIS OCCURS...NRLY WINDS WILL BEGIN TO INCREASE ACROSS LAKE SUPERIOR THIS AFTN AND MORE SO THIS EVENING AND OVERNIGHT. EXPECT NRLY WINDS IN THE 20-30KT RANGE TONIGHT WITH THE STRONGEST WINDS OVER THE E HALF OF THE LAKE. IT`S NOT OUT OF THE QUESTION THAT SOME GALE FORCE GUSTS COULD OCCUR...BUT SINCE THERE IS A LACK OF COLD AIR ADVECTION TO INCREASE MIXING...WILL HOLD OFF ON ANY MENTION OF GALES. PROGRESSION OF THE MAIN WEATHER SYSTEMS WILL SLOW TO A CRAWL TUE THRU FRI. WITH LOW PRES TO THE E AND HIGH PRES TO THE W...N TO NW WINDS WILL BE THE RULE TUE THRU FRI WITH THE STRONGEST WINDS REMAINING OVER THE E HALF OF LAKE SUPERIOR. OVERALL...AFTER TUE...WINDS SHOULD GENERALLY BE IN THE 15-25KT RANGE OVER THE E AND 10-20KT OVER THE W. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ UPDATE...MZ SYNOPSIS/DISCUSSION...AJ AVIATION...MZ MARINE...ROLFSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1030 AM EST MON NOV 24 2008 .UPDATE... UPPER LOW CONTINUES TO DROP SOUTHEASTWARD OUT OF WESTERN ONTARIO TOWARDS WESTERN LAKE SUPERIOR THIS MORNING. EVENTUALLY UPPER LOW WILL MERGE WITH S/WV OVER SOUTHERN LAKE MI FORMING BROADER UPPER LOW OVER SOUTHERN GREAT LAKES. WEAK SFC LOW CURRENTLY OVER SOUTHERN LOWER MI WILL MOVE SLOWLY EWD TO SOUTHERN LAKE HURON BY THE END OF THE DAY. BACK EDGE OF LIGHT SNOW FIELD ASSOCIATED WITH THESE FEATURES HAS MOVED INTO LAKE MI. BEST CHANCE FOR LIGHT SNOW THIS AFTERNOON WILL BE EAST OF A MANISTIQUE TO NEWBERRY LINE AND EVEN THERE AMOUNTS SHOULD BE LIGHT. AS MAIN UPPER LOW DROPS SOUTHEASTWARD ACROSS FAR WESTERN LAKE SUPERIOR EXPECT FLURRIES/-SHSN TO ACCOMPANY IT. WITH A SLIGHTLY WESTWARD UPPER LOW TRACK EXPECT BEST CHANCE OF THIS ACTIVITY ACROSS WESTERN UPPER MICHIGAN WITH CENTRAL AREAS REMAINING PRECIP FREE THROUGH MUCH OF THE DAY. 85H TEMPS WILL FALL INTO THE -8 TO -10 RANGE OVER WESTERN LAKE SUPERIOR AND AS WINDS BECOME MORE NORTHWESTERLY DO EXPECT SOME LAKE ENHANCEMENT TO OCCUR IN FAVORABLE UPSLOPE AREAS IN THE WEST. STILL NOT EXPECTING ANYTHING MORE THAN AN INCH OR AT MOST 2 OF ACCUMULATION DURING THE DAY TODAY. OVERALL TEMP FORECAST IS ON TRACK AND WILL NOT MAKE ANY ADJUSTMENTS TO IT. .SYNOPSIS... ISSUED AT 425 AM EST 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING OVER THE WESTERN U.S. INTO SW CANADA...RIDGING IN THE OHIO VALLEY INTO THE EASTERN GREAT LAKES...AND A TROUGH FROM MANITOBA SOUTHWARD INTO THE CENTRAL PLAINS. WITHIN THE TROUGH...AN UPPER LOW IS LOCATED AT THE FAR NORTH END OF LAKE WINNIPEG. THE WARM CONVEYOR BELT AHEAD OF THE UPPER LOW EXTENDS FROM MO ACROSS UPPER MI AND INTO NE ONTARIO. SOME -SN IS FALLING OUT OF THE CONVEYOR BELT OVER THE CENTRAL PORTION OF THE CWA...ALSO IN THE SAME PLACE WHERE BETTER MOISTURE IS BASED ON 00Z RAOBS FROM MPX...COMPARED TO GRB AND APX WHICH REFLECT THE DRIER AIRMASS OVER EASTERN UPPER MI. A DRY SLOT IS EVIDENT ON 11-3.9 U IMAGERY OVER NE MN...BUT FARTHER NW OVER NW MN INTO MANITOBA IS THE COLD CONVEYOR BELT (CCB) CLOUDS ON THE BACK SIDE OF THE UPPER LOW. 850MB TEMPS UNDER THE CCB WERE AROUND -14C BASED ON THE 00Z SOUNDING FROM CYQD...QUITE A BIT COLDER THAN THE -1C AT MPX...-4C AT INL AND -6C AT CWPL. TO THE SW OF UPPER MI ON WATER VAPOR...A SHRTWV IS MOVING THROUGH SRN IA. ASSOCIATED WITH THE SHRTWV IS A 1015MB SFC LOW IN SE IA. A TROUGH EXTENDS NE FROM THE LOW ACROSS CENTRAL UPPER MI...THEN HEADS BACK TO THE NW AS A COLD FRONT WHERE IT CONNECTS UP TO A 1008MB LOW IN FAR NW ONTARIO. && .DISCUSSION... ISSUED AT 425 AM EST MAIN FORECAST CONCERNS ARE THE AMOUNT OF SNOW THE NEXT TWO DAYS... ALONG WITH POTENTIAL FOR FREEZING DRIZZLE. TODAY...UPPER LOW AT THE NORTH END OF LAKE WINNIPEG IS PROGGED TO SLIDE A LITTLE BIT FARTHER WEST COMPARED TO YESTERDAYS 00Z RUNS...MOVING INTO WRN WI AT 00Z TUE. THE BULK OF THE COLD AIR SEEN UPSTREAM AT CYQD WILL STAY UNDER OR TO THE WEST OF THE UPPER LOW. HOWEVER...SOME COOLING IS STILL EXPECTED TO COME INTO UPPER MICHIGAN WITH THE APPROACH OF THE UPPER LOW. NAM/GFS SHOW 850MB TEMPS FALLING TO -8 TO -10C OVER WRN LAKE SUPERIOR...WHICH WOULD BE GOOD ENOUGH FOR LAKE ENHANCED OR PERHAPS EVEN PURE LAKE EFFECT. WITH NW WINDS... IT WOULD SEEM LIKELY FOR SNOW IN WRN UPPER MI...ESPECIALLY IN UPSLOPE AREAS. HAVE RAISED POPS TO DEFINITE IN THE UPSLOPE AREA FROM IWD TO ROCKLAND. SOUNDINGS SUGGEST SNOW TO WATER RATIOS SOMEWHERE AROUND 10 TO 1...DUE TO MAJORITY OF VERTICAL MOTION BELOW THE DENDRITIC SNOW GROWTH ZONE...WHICH WITH A BLEND OF NAM/LOCAL WRF-ARW RUN/GFS FOR QPF RESULTS IN 1 TO 2 INCHES. THE AMOUNT OF COLD AIR CROSSING CENTRAL AND LAKE SUPERIOR IS A LITTLE MORE UNCERTAIN... WITH THE GFS SHOWING -8 TO PERHAPS -10C AT 00Z TUE...COMPARED TO THE NAM AND LOCAL WRF-ARW WHICH HAVE -4 TO -6C. EITHER SCENARIO SEEMS AT LEAST POSSIBLE FOR LAKE ENHANCED PCPN...ESPECIALLY GIVEN THAT THERE WILL BE PLENTY OF MOISTURE AROUND IN THE WARM CONVEYOR BELT AHEAD OF THE UPPER LOW. THE PROBLEM IS THAT THE WARMER SCENARIO WOULD RESULT IN POTENTIAL FOR RAIN TO MIX IN...PARTICULARLY OVER LAKE SUPERIOR AND OVER LAND NEAR THE SUPERIOR SHORELINE. GIVEN 00Z SOUNDING FROM CWPL UPSTREAM WAS -6C...WILL LEAN TOWARDS THE NAM/LOCAL WRF-ARW. THE WARMER SCENARIO ALSO MEANS THAT ANY SNOW THAT FALLS INLAND WILL ALSO BE WETTER WITH SNOW TO WATER RATIOS LESS THAN 10 TO 1. COULD BE AN INCH...PERHAPS TWO OF THIS WET SNOW IN THE EASTERN CWA. THE CENTRAL U.P. LOOKS TO BE MAINLY DRY TODAY...WITH SOME SUN AS THE DRY-SLOT WORKS IN. A FEW -SHSN COULD WORK IN OVER MQT COUNTY OFF OF WRN SUPERIOR IN THE AFTN...BUT THAT IS ABOUT IT FOR CENTRAL UPPER MI. ALTHOUGH COLD AIR IS FLOWING IN...EXPECT HIGHS AGAIN TODAY IN THE 30S...WARMEST SOUTH CENTRAL WITH DOWNSLOPING NW WINDS AND NEAR LAKE SUPERIOR WITH HEAT FLUX OFF THE WARMER WATER. TONIGHT...UPPER LOW MOVES SE INTO OHIO BY 12Z TUE...COMING CLOSE TO PHASING WITH THE SHRTWV CURRENTLY HEADING EAST OUT OF SRN IA. AS A RESULT...THE SFC LOWS THAT ARE CURRENTLY IN NW ONTARIO AND SE IA END UP MERGING TOGETHER INTO A DEEPER 1003 MB LOW NEAR LONDON ONTARIO AT 12Z TUE. THE DEEPENING LOW HELPS TO STRENGTHEN NORTH TO NE WINDS OVER EASTERN LAKE SUPERIOR. NORMALLY THIS WOULD SPELL COLDER AIR MOVING IN. HOWEVER...THE AIR COMING IN IS EITHER JUST AS COOL OR PERHAPS EVEN SLIGHTLY WARMER THAN THE AIR THAT IS IN OVER THE CWA AT 00Z PER 850MB TEMP PROGS. THE REASON IS THAT THE DEEPENING LOW HELPS TO PULL WARMER AIR IN OFF THE ATLANTIC INTO ITS CIRCULATION. SO WITH LITTLE TO NO CHANGE IN 850MB TEMPS...LAKE ENHANCEMENT SHOULD BE THE RULE...POSSIBLY PURE LAKE EFFECT IN THE WRN U.P.. PROBLEM IN THE WRN U.P. COMPARED TO TODAY IS THAT WITH THE DEPARTURE OF THE UPPER LOW...INVERSIONS FALL WITH THE MID-LEVEL HEIGHT RISES. THE QUESTION IS IF THE -10C ISOTHERM DRIES OUT...WHICH WOULD CHANGE THE PCPN FROM SNOW TO FZDZ GIVEN THAT AN UPSLOPING WIND CONTINUES. RIGHT NOW ONLY OUR LOCAL WRF-ARW RUN SHOWS THIS OCCURRING...WHILE THE NAM/GFS SHOW THE -10C ISOTHERM REMAINING MOIST. THEREFORE HAVE DECIDED TO KEEP THE P-TYPE AS SNOW. IN THE CENTRAL AND EAST...INVERSIONS WILL GRADUALLY LOWER AS WELL...BUT NOT AS QUICK. SO CONFIDENCE IS HIGHER THAT THE P-TYPE WILL STAY AS SNOW INLAND FROM LAKE SUPERIOR. AMOUNTS OF SNOW SHOULD NOT BE THAT IMPRESSIVE...MAYBE AN INCH OR TWO GIVEN LOW SNOW TO WATER RATIOS. REGARDING AREAS NEAR THE LAKE...THE WARMER NAM/LOCAL WRF-ARW RUNS SUGGEST HOLDING ON TO A RAIN/SNOW MIX THROUGH AT LEAST 09Z. IF THE PCPN IS GENERALLY LIGHT...THEN MORE OF THE PCPN SHOULD FALL AS RAIN. GIVEN THE WARMER 850MB TEMPS AND PLENTY OF CLOUDS...ALONG WITH A FLOW OF AIR OFF THE WARM LAKE SUPERIOR WATER...TEMPS SHOULD NOT DROP TOO MUCH. COLDEST READINGS EXPECTED IN THE INTERIOR WEST...CLOSEST TO THE COLDEST 850MB AIR...BUT EVEN THESE SHOULD ONLY BE IN THE MID 20S. TUESDAY...UPPER LOW IS PROGGED TO SHIFT INTO NORTH CENTRAL PA BY 00Z WED...WITH THE SFC LOW MOVING TO THE LAKE ONTARIO AREA. THIS ALLOWS A HIGH PRESSURE RIDGE TO BUILD INTO WESTERN UPPER MI BY 00Z...IN ADDITION TO CONTINUED MID-LEVEL HEIGHT RISES THROUGH THE DAY. THE RIDGE SHOULD BRING DRIER AIR IN...LIKELY TO THE WESTERN CWA...ENOUGH TO END PCPN BY EARLY AFTN. HOWEVER...THE CENTRAL AND EASTERN CWA WILL STAY IN LOW CLOUDS TRAPPED UNDER THE LOWERING INVERSION... ENHANCED BY LAKE SUPERIOR GIVEN COOL AIR BELOW THE INVERSION. PCPN TYPE IS VERY TRICKY...AS ALL MODELS SHOW THE -10C LAYER DRYING OUT THROUGH THE DAY. GIVEN A NORTH WIND OVER EASTERN LAKE SUPERIOR...SET UP IS FAVORABLE FOR UPSLOPE. SO WITH LAKE ENHANCEMENT OFF LAKE SUPERIOR AND UPSLOPE FLOW PRODUCING VERTICAL MOTION...SOME PCPN SHOULD OCCUR OUT OF THE CLOUDS. RIGHT NOW HAVE GONE WITH EITHER SNOW SHOWERS OR DZ/FZDZ (FZDZ OVER INLAND AREAS THROUGH THE EARLY AFTN). POPS ARE HIGHEST IN THE UPSLOPE AREAS OF THE NORTH CENTRAL IN THE MORNING...THEN DECREASE IN THE AFTN AS THE DRIER AIR TRIES TO WORK IN. GIVEN CLOUD COVER AND 850MB TEMPS THAT ARE SLIGHTLY COOLER THAN TODAY...HIGHS WILL ALSO END UP SLIGHTLY COOLER. STILL...MOST LOCATIONS SHOULD BE IN THE 30S...WARMEST IN THE DOWNSLOPE AREAS OF THE SOUTH CENTRAL. TUE NIGHT THROUGH THU...PER THE UKMET/NAM/GFS/ECMWF...UPPER MI LOOKS TO BE CAUGHT IN SQUEEZE-PLAY AS THE UPPER LEVEL PATTERN OVER CANADA AND THE NORTHERN U.S. BECOMES BLOCKED. THIS BLOCKING LOOKS TO BE A RESULT OF STRONG RIDGING BUILT UP AHEAD OF THE UPPER LOW TO OUR EAST. IN FACT...MODELS ARE IN GOOD AGREEMENT TAKING THE UPPER LOW BACK TO THE NW DURING THIS PERIOD...BASICALLY PULLED BY THE CURRENT SHRTWV CROSSING SRN IA. WHAT THIS MEANS FOR UPPER MI IS A PERSISTENT CHANCE FOR -SN ACROSS THE EAST HALF OF UPPER MI CLOSER TO THE DEEPER MOISTURE AROUND THE UPPER LOW...WHILE THE WEST HALF OF UPPER MI IS DRY WITH PARTLY CLOUDY SKIES UNDER THE INFLUENCE OF LOW INVERSIONS AND THE SURFACE RIDGE. STILL MAINTAINED THE POSSIBILITY OF SOME DZ/FZDZ OVER THE EASTERN CWA TUE NIGHT SINCE IT DOES NOT APPEAR THAT THE DEEPER MOISTURE WILL MOVE IN UNTIL WED. ANY PCPN LOOKS TO BE LIGHT AT THE CURRENT TIME DUE TO LACK OF SIGNIFICANT MOISTURE WITH THE UPPER LOW. GIVEN THE BLOCKED PATTERN...NO SIGNIFICANT COOLING OR WARMING IS PLANNED. THEREFORE... LOWS AND HIGHS ARE FORECAST TO BE ABOUT THE SAME THROUGH THE PERIOD...IN THE 20S AND 30S RESPECTIVELY. BEYOND THU...NO SIGNIFICANT CHANGES MADE. 00Z ECMWF/GFS/GFS ENSEMBLES ARE ALL IN VERY GOOD AGREEMENT SHOWING THE DEVELOPMENT OF A BROAD TROUGH ACROSS THE GREAT LAKES INTO THE OHIO VALLEY FOR FRI INTO THE WEEKEND. THIS TROUGH IS FORMED BY A COMBINATION OF THE UPPER LOW TO OUR EAST ON THU AND ANOTHER TROUGH DROPPING DOWN OUT OF CENTRAL CANADA. THIS MEANS THAT GRADUAL COOLING WILL OCCUR...COLD ENOUGH TO SET UP PURE LAKE EFFECT BY THE WEEKEND. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... OVERALL...EXPECT MVFR CONDITIONS TO PREVAIL AT KCMX/KSAW THRU THIS FCST PERIOD. WEDGE OF SOMEWHAT DRIER AIR SWEEPING INTO THE AREA AHEAD OF MID/UPPER LOW DROPPING SE TOWARD THE UPPER MIDWEST MAY RESULT IN CLOUDS SCATTERING OUT FOR A WHILE TODAY...BUT CONFIDENCE IS LOW IN DETERMINING A TIME PERIOD WHEN THAT MIGHT OCCUR. OTHERWISE...UPPER LOW DROPPING INTO THE VCNTY WILL LIKELY BRING SOME -SHSN TO KCMX THIS AFTN AND KSAW THIS EVENING. SOME LAKE ENHANCEMENT IS EXPECTED...ESPECIALLY AT KSAW AS CONVERGENT NRLY UPSLOPING FLOW DEVELOPS. MAY SEE IFR CONDITIONS FOR A TIME LATE EVENING INTO THE OVERNIGHT. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A LOW PRES TROF EXTENDING FROM NORTHERN ONTARIO ACROSS THE UPPER GREAT LAKES TO THE MID MISSISSIPPI RIVER VALLEY WILL CONSOLIDATE INTO A LOW PRES CENTER OVER SRN LAKE HURON THIS EVENING. AS THIS OCCURS...NRLY WINDS WILL BEGIN TO INCREASE ACROSS LAKE SUPERIOR THIS AFTN AND MORE SO THIS EVENING AND OVERNIGHT. EXPECT NRLY WINDS IN THE 20-30KT RANGE TONIGHT WITH THE STRONGEST WINDS OVER THE E HALF OF THE LAKE. IT`S NOT OUT OF THE QUESTION THAT SOME GALE FORCE GUSTS COULD OCCUR...BUT SINCE THERE IS A LACK OF COLD AIR ADVECTION TO INCREASE MIXING...WILL HOLD OFF ON ANY MENTION OF GALES. PROGRESSION OF THE MAIN WEATHER SYSTEMS WILL SLOW TO A CRAWL TUE THRU FRI. WITH LOW PRES TO THE E AND HIGH PRES TO THE W...N TO NW WINDS WILL BE THE RULE TUE THRU FRI WITH THE STRONGEST WINDS REMAINING OVER THE E HALF OF LAKE SUPERIOR. OVERALL...AFTER TUE...WINDS SHOULD GENERALLY BE IN THE 15-25KT RANGE OVER THE E AND 10-20KT OVER THE W. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ UPDATE...MZ SYNOPSIS/DISCUSSION...AJ AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 646 AM EST MON NOV 24 2008 UPDATED AVIATION DISCUSSION FOR 12Z TAF ISSUANCE .SYNOPSIS... ISSUED AT 425 AM EST 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING OVER THE WESTERN U.S. INTO SW CANADA...RIDGING IN THE OHIO VALLEY INTO THE EASTERN GREAT LAKES...AND A TROUGH FROM MANITOBA SOUTHWARD INTO THE CENTRAL PLAINS. WITHIN THE TROUGH...AN UPPER LOW IS LOCATED AT THE FAR NORTH END OF LAKE WINNIPEG. THE WARM CONVEYOR BELT AHEAD OF THE UPPER LOW EXTENDS FROM MO ACROSS UPPER MI AND INTO NE ONTARIO. SOME -SN IS FALLING OUT OF THE CONVEYOR BELT OVER THE CENTRAL PORTION OF THE CWA...ALSO IN THE SAME PLACE WHERE BETTER MOISTURE IS BASED ON 00Z RAOBS FROM MPX...COMPARED TO GRB AND APX WHICH REFLECT THE DRIER AIRMASS OVER EASTERN UPPER MI. A DRY SLOT IS EVIDENT ON 11-3.9 U IMAGERY OVER NE MN...BUT FARTHER NW OVER NW MN INTO MANITOBA IS THE COLD CONVEYOR BELT (CCB) CLOUDS ON THE BACK SIDE OF THE UPPER LOW. 850MB TEMPS UNDER THE CCB WERE AROUND -14C BASED ON THE 00Z SOUNDING FROM CYQD...QUITE A BIT COLDER THAN THE -1C AT MPX...-4C AT INL AND -6C AT CWPL. TO THE SW OF UPPER MI ON WATER VAPOR...A SHRTWV IS MOVING THROUGH SRN IA. ASSOCIATED WITH THE SHRTWV IS A 1015MB SFC LOW IN SE IA. A TROUGH EXTENDS NE FROM THE LOW ACROSS CENTRAL UPPER MI...THEN HEADS BACK TO THE NW AS A COLD FRONT WHERE IT CONNECTS UP TO A 1008MB LOW IN FAR NW ONTARIO. && .DISCUSSION... ISSUED AT 425 AM EST MAIN FORECAST CONCERNS ARE THE AMOUNT OF SNOW THE NEXT TWO DAYS... ALONG WITH POTENTIAL FOR FREEZING DRIZZLE. TODAY...UPPER LOW AT THE NORTH END OF LAKE WINNIPEG IS PROGGED TO SLIDE A LITTLE BIT FARTHER WEST COMPARED TO YESTERDAYS 00Z RUNS...MOVING INTO WRN WI AT 00Z TUE. THE BULK OF THE COLD AIR SEEN UPSTREAM AT CYQD WILL STAY UNDER OR TO THE WEST OF THE UPPER LOW. HOWEVER...SOME COOLING IS STILL EXPECTED TO COME INTO UPPER MICHIGAN WITH THE APPROACH OF THE UPPER LOW. NAM/GFS SHOW 850MB TEMPS FALLING TO -8 TO -10C OVER WRN LAKE SUPERIOR...WHICH WOULD BE GOOD ENOUGH FOR LAKE ENHANCED OR PERHAPS EVEN PURE LAKE EFFECT. WITH NW WINDS... IT WOULD SEEM LIKELY FOR SNOW IN WRN UPPER MI...ESPECIALLY IN UPSLOPE AREAS. HAVE RAISED POPS TO DEFINITE IN THE UPSLOPE AREA FROM IWD TO ROCKLAND. SOUNDINGS SUGGEST SNOW TO WATER RATIOS SOMEWHERE AROUND 10 TO 1...DUE TO MAJORITY OF VERTICAL MOTION BELOW THE DENDRITIC SNOW GROWTH ZONE...WHICH WITH A BLEND OF NAM/LOCAL WRF-ARW RUN/GFS FOR QPF RESULTS IN 1 TO 2 INCHES. THE AMOUNT OF COLD AIR CROSSING CENTRAL AND LAKE SUPERIOR IS A LITTLE MORE UNCERTAIN... WITH THE GFS SHOWING -8 TO PERHAPS -10C AT 00Z TUE...COMPARED TO THE NAM AND LOCAL WRF-ARW WHICH HAVE -4 TO -6C. EITHER SCENARIO SEEMS AT LEAST POSSIBLE FOR LAKE ENHANCED PCPN...ESPECIALLY GIVEN THAT THERE WILL BE PLENTY OF MOISTURE AROUND IN THE WARM CONVEYOR BELT AHEAD OF THE UPPER LOW. THE PROBLEM IS THAT THE WARMER SCENARIO WOULD RESULT IN POTENTIAL FOR RAIN TO MIX IN...PARTICULARLY OVER LAKE SUPERIOR AND OVER LAND NEAR THE SUPERIOR SHORELINE. GIVEN 00Z SOUNDING FROM CWPL UPSTREAM WAS -6C...WILL LEAN TOWARDS THE NAM/LOCAL WRF-ARW. THE WARMER SCENARIO ALSO MEANS THAT ANY SNOW THAT FALLS INLAND WILL ALSO BE WETTER WITH SNOW TO WATER RATIOS LESS THAN 10 TO 1. COULD BE AN INCH...PERHAPS TWO OF THIS WET SNOW IN THE EASTERN CWA. THE CENTRAL U.P. LOOKS TO BE MAINLY DRY TODAY...WITH SOME SUN AS THE DRY-SLOT WORKS IN. A FEW -SHSN COULD WORK IN OVER MQT COUNTY OFF OF WRN SUPERIOR IN THE AFTN...BUT THAT IS ABOUT IT FOR CENTRAL UPPER MI. ALTHOUGH COLD AIR IS FLOWING IN...EXPECT HIGHS AGAIN TODAY IN THE 30S...WARMEST SOUTH CENTRAL WITH DOWNSLOPING NW WINDS AND NEAR LAKE SUPERIOR WITH HEAT FLUX OFF THE WARMER WATER. TONIGHT...UPPER LOW MOVES SE INTO OHIO BY 12Z TUE...COMING CLOSE TO PHASING WITH THE SHRTWV CURRENTLY HEADING EAST OUT OF SRN IA. AS A RESULT...THE SFC LOWS THAT ARE CURRENTLY IN NW ONTARIO AND SE IA END UP MERGING TOGETHER INTO A DEEPER 1003 MB LOW NEAR LONDON ONTARIO AT 12Z TUE. THE DEEPENING LOW HELPS TO STRENGTHEN NORTH TO NE WINDS OVER EASTERN LAKE SUPERIOR. NORMALLY THIS WOULD SPELL COLDER AIR MOVING IN. HOWEVER...THE AIR COMING IN IS EITHER JUST AS COOL OR PERHAPS EVEN SLIGHTLY WARMER THAN THE AIR THAT IS IN OVER THE CWA AT 00Z PER 850MB TEMP PROGS. THE REASON IS THAT THE DEEPENING LOW HELPS TO PULL WARMER AIR IN OFF THE ATLANTIC INTO ITS CIRCULATION. SO WITH LITTLE TO NO CHANGE IN 850MB TEMPS...LAKE ENHANCEMENT SHOULD BE THE RULE...POSSIBLY PURE LAKE EFFECT IN THE WRN U.P.. PROBLEM IN THE WRN U.P. COMPARED TO TODAY IS THAT WITH THE DEPARTURE OF THE UPPER LOW...INVERSIONS FALL WITH THE MID-LEVEL HEIGHT RISES. THE QUESTION IS IF THE -10C ISOTHERM DRIES OUT...WHICH WOULD CHANGE THE PCPN FROM SNOW TO FZDZ GIVEN THAT AN UPSLOPING WIND CONTINUES. RIGHT NOW ONLY OUR LOCAL WRF-ARW RUN SHOWS THIS OCCURRING...WHILE THE NAM/GFS SHOW THE -10C ISOTHERM REMAINING MOIST. THEREFORE HAVE DECIDED TO KEEP THE P-TYPE AS SNOW. IN THE CENTRAL AND EAST...INVERSIONS WILL GRADUALLY LOWER AS WELL...BUT NOT AS QUICK. SO CONFIDENCE IS HIGHER THAT THE P-TYPE WILL STAY AS SNOW INLAND FROM LAKE SUPERIOR. AMOUNTS OF SNOW SHOULD NOT BE THAT IMPRESSIVE...MAYBE AN INCH OR TWO GIVEN LOW SNOW TO WATER RATIOS. REGARDING AREAS NEAR THE LAKE...THE WARMER NAM/LOCAL WRF-ARW RUNS SUGGEST HOLDING ON TO A RAIN/SNOW MIX THROUGH AT LEAST 09Z. IF THE PCPN IS GENERALLY LIGHT...THEN MORE OF THE PCPN SHOULD FALL AS RAIN. GIVEN THE WARMER 850MB TEMPS AND PLENTY OF CLOUDS...ALONG WITH A FLOW OF AIR OFF THE WARM LAKE SUPERIOR WATER...TEMPS SHOULD NOT DROP TOO MUCH. COLDEST READINGS EXPECTED IN THE INTERIOR WEST...CLOSEST TO THE COLDEST 850MB AIR...BUT EVEN THESE SHOULD ONLY BE IN THE MID 20S. TUESDAY...UPPER LOW IS PROGGED TO SHIFT INTO NORTH CENTRAL PA BY 00Z WED...WITH THE SFC LOW MOVING TO THE LAKE ONTARIO AREA. THIS ALLOWS A HIGH PRESSURE RIDGE TO BUILD INTO WESTERN UPPER MI BY 00Z...IN ADDITION TO CONTINUED MID-LEVEL HEIGHT RISES THROUGH THE DAY. THE RIDGE SHOULD BRING DRIER AIR IN...LIKELY TO THE WESTERN CWA...ENOUGH TO END PCPN BY EARLY AFTN. HOWEVER...THE CENTRAL AND EASTERN CWA WILL STAY IN LOW CLOUDS TRAPPED UNDER THE LOWERING INVERSION... ENHANCED BY LAKE SUPERIOR GIVEN COOL AIR BELOW THE INVERSION. PCPN TYPE IS VERY TRICKY...AS ALL MODELS SHOW THE -10C LAYER DRYING OUT THROUGH THE DAY. GIVEN A NORTH WIND OVER EASTERN LAKE SUPERIOR...SET UP IS FAVORABLE FOR UPSLOPE. SO WITH LAKE ENHANCEMENT OFF LAKE SUPERIOR AND UPSLOPE FLOW PRODUCING VERTICAL MOTION...SOME PCPN SHOULD OCCUR OUT OF THE CLOUDS. RIGHT NOW HAVE GONE WITH EITHER SNOW SHOWERS OR DZ/FZDZ (FZDZ OVER INLAND AREAS THROUGH THE EARLY AFTN). POPS ARE HIGHEST IN THE UPSLOPE AREAS OF THE NORTH CENTRAL IN THE MORNING...THEN DECREASE IN THE AFTN AS THE DRIER AIR TRIES TO WORK IN. GIVEN CLOUD COVER AND 850MB TEMPS THAT ARE SLIGHTLY COOLER THAN TODAY...HIGHS WILL ALSO END UP SLIGHTLY COOLER. STILL...MOST LOCATIONS SHOULD BE IN THE 30S...WARMEST IN THE DOWNSLOPE AREAS OF THE SOUTH CENTRAL. TUE NIGHT THROUGH THU...PER THE UKMET/NAM/GFS/ECMWF...UPPER MI LOOKS TO BE CAUGHT IN SQUEEZE-PLAY AS THE UPPER LEVEL PATTERN OVER CANADA AND THE NORTHERN U.S. BECOMES BLOCKED. THIS BLOCKING LOOKS TO BE A RESULT OF STRONG RIDGING BUILT UP AHEAD OF THE UPPER LOW TO OUR EAST. IN FACT...MODELS ARE IN GOOD AGREEMENT TAKING THE UPPER LOW BACK TO THE NW DURING THIS PERIOD...BASICALLY PULLED BY THE CURRENT SHRTWV CROSSING SRN IA. WHAT THIS MEANS FOR UPPER MI IS A PERSISTENT CHANCE FOR -SN ACROSS THE EAST HALF OF UPPER MI CLOSER TO THE DEEPER MOISTURE AROUND THE UPPER LOW...WHILE THE WEST HALF OF UPPER MI IS DRY WITH PARTLY CLOUDY SKIES UNDER THE INFLUENCE OF LOW INVERSIONS AND THE SURFACE RIDGE. STILL MAINTAINED THE POSSIBILITY OF SOME DZ/FZDZ OVER THE EASTERN CWA TUE NIGHT SINCE IT DOES NOT APPEAR THAT THE DEEPER MOISTURE WILL MOVE IN UNTIL WED. ANY PCPN LOOKS TO BE LIGHT AT THE CURRENT TIME DUE TO LACK OF SIGNIFICANT MOISTURE WITH THE UPPER LOW. GIVEN THE BLOCKED PATTERN...NO SIGNIFICANT COOLING OR WARMING IS PLANNED. THEREFORE... LOWS AND HIGHS ARE FORECAST TO BE ABOUT THE SAME THROUGH THE PERIOD...IN THE 20S AND 30S RESPECTIVELY. BEYOND THU...NO SIGNIFICANT CHANGES MADE. 00Z ECMWF/GFS/GFS ENSEMBLES ARE ALL IN VERY GOOD AGREEMENT SHOWING THE DEVELOPMENT OF A BROAD TROUGH ACROSS THE GREAT LAKES INTO THE OHIO VALLEY FOR FRI INTO THE WEEKEND. THIS TROUGH IS FORMED BY A COMBINATION OF THE UPPER LOW TO OUR EAST ON THU AND ANOTHER TROUGH DROPPING DOWN OUT OF CENTRAL CANADA. THIS MEANS THAT GRADUAL COOLING WILL OCCUR...COLD ENOUGH TO SET UP PURE LAKE EFFECT BY THE WEEKEND. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... OVERALL...EXPECT MVFR CONDITIONS TO PREVAIL AT KCMX/KSAW THRU THIS FCST PERIOD. WEDGE OF SOMEWHAT DRIER AIR SWEEPING INTO THE AREA AHEAD OF MID/UPPER LOW DROPPING SE TOWARD THE UPPER MIDWEST MAY RESULT IN CLOUDS SCATTERING OUT FOR A WHILE TODAY...BUT CONFIDENCE IS LOW IN DETERMINING A TIME PERIOD WHEN THAT MIGHT OCCUR. OTHERWISE...UPPER LOW DROPPING INTO THE VCNTY WILL LIKELY BRING SOME -SHSN TO KCMX THIS AFTN AND KSAW THIS EVENING. SOME LAKE ENHANCEMENT IS EXPECTED...ESPECIALLY AT KSAW AS CONVERGENT NRLY UPSLOPING FLOW DEVELOPS. MAY SEE IFR CONDITIONS FOR A TIME LATE EVENING INTO THE OVERNIGHT. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A LOW PRES TROF EXTENDING FROM NORTHERN ONTARIO ACROSS THE UPPER GREAT LAKES TO THE MID MISSISSIPPI RIVER VALLEY WILL CONSOLIDATE INTO A LOW PRES CENTER OVER SRN LAKE HURON THIS EVENING. AS THIS OCCURS...NRLY WINDS WILL BEGIN TO INCREASE ACROSS LAKE SUPERIOR THIS AFTN AND MORE SO THIS EVENING AND OVERNIGHT. EXPECT NRLY WINDS IN THE 20-30KT RANGE TONIGHT WITH THE STRONGEST WINDS OVER THE E HALF OF THE LAKE. IT`S NOT OUT OF THE QUESTION THAT SOME GALE FORCE GUSTS COULD OCCUR...BUT SINCE THERE IS A LACK OF COLD AIR ADVECTION TO INCREASE MIXING...WILL HOLD OFF ON ANY MENTION OF GALES. PROGRESSION OF THE MAIN WEATHER SYSTEMS WILL SLOW TO A CRAWL TUE THRU FRI. WITH LOW PRES TO THE E AND HIGH PRES TO THE W...N TO NW WINDS WILL BE THE RULE TUE THRU FRI WITH THE STRONGEST WINDS REMAINING OVER THE E HALF OF LAKE SUPERIOR. OVERALL...AFTER TUE...WINDS SHOULD GENERALLY BE IN THE 15-25KT RANGE OVER THE E AND 10-20KT OVER THE W. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 425 AM EST MON NOV 24 2008 .SYNOPSIS... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING OVER THE WESTERN U.S. INTO SW CANADA...RIDGING IN THE OHIO VALLEY INTO THE EASTERN GREAT LAKES...AND A TROUGH FROM MANITOBA SOUTHWARD INTO THE CENTRAL PLAINS. WITHIN THE TROUGH...AN UPPER LOW IS LOCATED AT THE FAR NORTH END OF LAKE WINNIPEG. THE WARM CONVEYOR BELT AHEAD OF THE UPPER LOW EXTENDS FROM MO ACROSS UPPER MI AND INTO NE ONTARIO. SOME -SN IS FALLING OUT OF THE CONVEYOR BELT OVER THE CENTRAL PORTION OF THE CWA...ALSO IN THE SAME PLACE WHERE BETTER MOISTURE IS BASED ON 00Z RAOBS FROM MPX...COMPARED TO GRB AND APX WHICH REFLECT THE DRIER AIRMASS OVER EASTERN UPPER MI. A DRY SLOT IS EVIDENT ON 11-3.9 U IMAGERY OVER NE MN...BUT FARTHER NW OVER NW MN INTO MANITOBA IS THE COLD CONVEYOR BELT (CCB) CLOUDS ON THE BACK SIDE OF THE UPPER LOW. 850MB TEMPS UNDER THE CCB WERE AROUND -14C BASED ON THE 00Z SOUNDING FROM CYQD...QUITE A BIT COLDER THAN THE -1C AT MPX...-4C AT INL AND -6C AT CWPL. TO THE SW OF UPPER MI ON WATER VAPOR...A SHRTWV IS MOVING THROUGH SRN IA. ASSOCIATED WITH THE SHRTWV IS A 1015MB SFC LOW IN SE IA. A TROUGH EXTENDS NE FROM THE LOW ACROSS CENTRAL UPPER MI...THEN HEADS BACK TO THE NW AS A COLD FRONT WHERE IT CONNECTS UP TO A 1008MB LOW IN FAR NW ONTARIO. && .DISCUSSION... MAIN FORECAST CONCERNS ARE THE AMOUNT OF SNOW THE NEXT TWO DAYS... ALONG WITH POTENTIAL FOR FREEZING DRIZZLE. TODAY...UPPER LOW AT THE NORTH END OF LAKE WINNIPEG IS PROGGED TO SLIDE A LITTLE BIT FARTHER WEST COMPARED TO YESTERDAYS 00Z RUNS...MOVING INTO WRN WI AT 00Z TUE. THE BULK OF THE COLD AIR SEEN UPSTREAM AT CYQD WILL STAY UNDER OR TO THE WEST OF THE UPPER LOW. HOWEVER...SOME COOLING IS STILL EXPECTED TO COME INTO UPPER MICHIGAN WITH THE APPROACH OF THE UPPER LOW. NAM/GFS SHOW 850MB TEMPS FALLING TO -8 TO -10C OVER WRN LAKE SUPERIOR...WHICH WOULD BE GOOD ENOUGH FOR LAKE ENHANCED OR PERHAPS EVEN PURE LAKE EFFECT. WITH NW WINDS... IT WOULD SEEM LIKELY FOR SNOW IN WRN UPPER MI...ESPECIALLY IN UPSLOPE AREAS. HAVE RAISED POPS TO DEFINITE IN THE UPSLOPE AREA FROM IWD TO ROCKLAND. SOUNDINGS SUGGEST SNOW TO WATER RATIOS SOMEWHERE AROUND 10 TO 1...DUE TO MAJORITY OF VERTICAL MOTION BELOW THE DENDRITIC SNOW GROWTH ZONE...WHICH WITH A BLEND OF NAM/LOCAL WRF-ARW RUN/GFS FOR QPF RESULTS IN 1 TO 2 INCHES. THE AMOUNT OF COLD AIR CROSSING CENTRAL AND LAKE SUPERIOR IS A LITTLE MORE UNCERTAIN... WITH THE GFS SHOWING -8 TO PERHAPS -10C AT 00Z TUE...COMPARED TO THE NAM AND LOCAL WRF-ARW WHICH HAVE -4 TO -6C. EITHER SCENARIO SEEMS AT LEAST POSSIBLE FOR LAKE ENHANCED PCPN...ESPECIALLY GIVEN THAT THERE WILL BE PLENTY OF MOISTURE AROUND IN THE WARM CONVEYOR BELT AHEAD OF THE UPPER LOW. THE PROBLEM IS THAT THE WARMER SCENARIO WOULD RESULT IN POTENTIAL FOR RAIN TO MIX IN...PARTICULARLY OVER LAKE SUPERIOR AND OVER LAND NEAR THE SUPERIOR SHORELINE. GIVEN 00Z SOUNDING FROM CWPL UPSTREAM WAS -6C...WILL LEAN TOWARDS THE NAM/LOCAL WRF-ARW. THE WARMER SCENARIO ALSO MEANS THAT ANY SNOW THAT FALLS INLAND WILL ALSO BE WETTER WITH SNOW TO WATER RATIOS LESS THAN 10 TO 1. COULD BE AN INCH...PERHAPS TWO OF THIS WET SNOW IN THE EASTERN CWA. THE CENTRAL U.P. LOOKS TO BE MAINLY DRY TODAY...WITH SOME SUN AS THE DRY-SLOT WORKS IN. A FEW -SHSN COULD WORK IN OVER MQT COUNTY OFF OF WRN SUPERIOR IN THE AFTN...BUT THAT IS ABOUT IT FOR CENTRAL UPPER MI. ALTHOUGH COLD AIR IS FLOWING IN...EXPECT HIGHS AGAIN TODAY IN THE 30S...WARMEST SOUTH CENTRAL WITH DOWNSLOPING NW WINDS AND NEAR LAKE SUPERIOR WITH HEAT FLUX OFF THE WARMER WATER. TONIGHT...UPPER LOW MOVES SE INTO OHIO BY 12Z TUE...COMING CLOSE TO PHASING WITH THE SHRTWV CURRENTLY HEADING EAST OUT OF SRN IA. AS A RESULT...THE SFC LOWS THAT ARE CURRENTLY IN NW ONTARIO AND SE IA END UP MERGING TOGETHER INTO A DEEPER 1003 MB LOW NEAR LONDON ONTARIO AT 12Z TUE. THE DEEPENING LOW HELPS TO STRENGTHEN NORTH TO NE WINDS OVER EASTERN LAKE SUPERIOR. NORMALLY THIS WOULD SPELL COLDER AIR MOVING IN. HOWEVER...THE AIR COMING IN IS EITHER JUST AS COOL OR PERHAPS EVEN SLIGHTLY WARMER THAN THE AIR THAT IS IN OVER THE CWA AT 00Z PER 850MB TEMP PROGS. THE REASON IS THAT THE DEEPENING LOW HELPS TO PULL WARMER AIR IN OFF THE ATLANTIC INTO ITS CIRCULATION. SO WITH LITTLE TO NO CHANGE IN 850MB TEMPS...LAKE ENHANCEMENT SHOULD BE THE RULE...POSSIBLY PURE LAKE EFFECT IN THE WRN U.P.. PROBLEM IN THE WRN U.P. COMPARED TO TODAY IS THAT WITH THE DEPARTURE OF THE UPPER LOW...INVERSIONS FALL WITH THE MID-LEVEL HEIGHT RISES. THE QUESTION IS IF THE -10C ISOTHERM DRIES OUT...WHICH WOULD CHANGE THE PCPN FROM SNOW TO FZDZ GIVEN THAT AN UPSLOPING WIND CONTINUES. RIGHT NOW ONLY OUR LOCAL WRF-ARW RUN SHOWS THIS OCCURRING...WHILE THE NAM/GFS SHOW THE -10C ISOTHERM REMAINING MOIST. THEREFORE HAVE DECIDED TO KEEP THE P-TYPE AS SNOW. IN THE CENTRAL AND EAST...INVERSIONS WILL GRADUALLY LOWER AS WELL...BUT NOT AS QUICK. SO CONFIDENCE IS HIGHER THAT THE P-TYPE WILL STAY AS SNOW INLAND FROM LAKE SUPERIOR. AMOUNTS OF SNOW SHOULD NOT BE THAT IMPRESSIVE...MAYBE AN INCH OR TWO GIVEN LOW SNOW TO WATER RATIOS. REGARDING AREAS NEAR THE LAKE...THE WARMER NAM/LOCAL WRF-ARW RUNS SUGGEST HOLDING ON TO A RAIN/SNOW MIX THROUGH AT LEAST 09Z. IF THE PCPN IS GENERALLY LIGHT...THEN MORE OF THE PCPN SHOULD FALL AS RAIN. GIVEN THE WARMER 850MB TEMPS AND PLENTY OF CLOUDS...ALONG WITH A FLOW OF AIR OFF THE WARM LAKE SUPERIOR WATER...TEMPS SHOULD NOT DROP TOO MUCH. COLDEST READINGS EXPECTED IN THE INTERIOR WEST...CLOSEST TO THE COLDEST 850MB AIR...BUT EVEN THESE SHOULD ONLY BE IN THE MID 20S. TUESDAY...UPPER LOW IS PROGGED TO SHIFT INTO NORTH CENTRAL PA BY 00Z WED...WITH THE SFC LOW MOVING TO THE LAKE ONTARIO AREA. THIS ALLOWS A HIGH PRESSURE RIDGE TO BUILD INTO WESTERN UPPER MI BY 00Z...IN ADDITION TO CONTINUED MID-LEVEL HEIGHT RISES THROUGH THE DAY. THE RIDGE SHOULD BRING DRIER AIR IN...LIKELY TO THE WESTERN CWA...ENOUGH TO END PCPN BY EARLY AFTN. HOWEVER...THE CENTRAL AND EASTERN CWA WILL STAY IN LOW CLOUDS TRAPPED UNDER THE LOWERING INVERSION... ENHANCED BY LAKE SUPERIOR GIVEN COOL AIR BELOW THE INVERSION. PCPN TYPE IS VERY TRICKY...AS ALL MODELS SHOW THE -10C LAYER DRYING OUT THROUGH THE DAY. GIVEN A NORTH WIND OVER EASTERN LAKE SUPERIOR...SET UP IS FAVORABLE FOR UPSLOPE. SO WITH LAKE ENHANCEMENT OFF LAKE SUPERIOR AND UPSLOPE FLOW PRODUCING VERTICAL MOTION...SOME PCPN SHOULD OCCUR OUT OF THE CLOUDS. RIGHT NOW HAVE GONE WITH EITHER SNOW SHOWERS OR DZ/FZDZ (FZDZ OVER INLAND AREAS THROUGH THE EARLY AFTN). POPS ARE HIGHEST IN THE UPSLOPE AREAS OF THE NORTH CENTRAL IN THE MORNING...THEN DECREASE IN THE AFTN AS THE DRIER AIR TRIES TO WORK IN. GIVEN CLOUD COVER AND 850MB TEMPS THAT ARE SLIGHTLY COOLER THAN TODAY...HIGHS WILL ALSO END UP SLIGHTLY COOLER. STILL...MOST LOCATIONS SHOULD BE IN THE 30S...WARMEST IN THE DOWNSLOPE AREAS OF THE SOUTH CENTRAL. TUE NIGHT THROUGH THU...PER THE UKMET/NAM/GFS/ECMWF...UPPER MI LOOKS TO BE CAUGHT IN SQUEEZE-PLAY AS THE UPPER LEVEL PATTERN OVER CANADA AND THE NORTHERN U.S. BECOMES BLOCKED. THIS BLOCKING LOOKS TO BE A RESULT OF STRONG RIDGING BUILT UP AHEAD OF THE UPPER LOW TO OUR EAST. IN FACT...MODELS ARE IN GOOD AGREEMENT TAKING THE UPPER LOW BACK TO THE NW DURING THIS PERIOD...BASICALLY PULLED BY THE CURRENT SHRTWV CROSSING SRN IA. WHAT THIS MEANS FOR UPPER MI IS A PERSISTENT CHANCE FOR -SN ACROSS THE EAST HALF OF UPPER MI CLOSER TO THE DEEPER MOISTURE AROUND THE UPPER LOW...WHILE THE WEST HALF OF UPPER MI IS DRY WITH PARTLY CLOUDY SKIES UNDER THE INFLUENCE OF LOW INVERSIONS AND THE SURFACE RIDGE. STILL MAINTAINED THE POSSIBILITY OF SOME DZ/FZDZ OVER THE EASTERN CWA TUE NIGHT SINCE IT DOES NOT APPEAR THAT THE DEEPER MOISTURE WILL MOVE IN UNTIL WED. ANY PCPN LOOKS TO BE LIGHT AT THE CURRENT TIME DUE TO LACK OF SIGNIFICANT MOISTURE WITH THE UPPER LOW. GIVEN THE BLOCKED PATTERN...NO SIGNIFICANT COOLING OR WARMING IS PLANNED. THEREFORE... LOWS AND HIGHS ARE FORECAST TO BE ABOUT THE SAME THROUGH THE PERIOD...IN THE 20S AND 30S RESPECTIVELY. BEYOND THU...NO SIGNIFICANT CHANGES MADE. 00Z ECMWF/GFS/GFS ENSEMBLES ARE ALL IN VERY GOOD AGREEMENT SHOWING THE DEVELOPMENT OF A BROAD TROUGH ACROSS THE GREAT LAKES INTO THE OHIO VALLEY FOR FRI INTO THE WEEKEND. THIS TROUGH IS FORMED BY A COMBINATION OF THE UPPER LOW TO OUR EAST ON THU AND ANOTHER TROUGH DROPPING DOWN OUT OF CENTRAL CANADA. THIS MEANS THAT GRADUAL COOLING WILL OCCUR...COLD ENOUGH TO SET UP PURE LAKE EFFECT BY THE WEEKEND. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... LIGHT SNOW ASSOCIATED WITH A TROUGH MOVING THROUGH UPPER MICHIGAN COULD BRING A PERIOD OF MVFR VSBY. WITH LOW LEVEL MOISTENING...MVFR CIGS ARE ALSO EXPECTED WITH THE POTENTIAL FOR OCNL IFR CIGS. THEN...AS NORTHWEST TO NORTHERLY FLOW SETS UP AND COLD AIR MOVES IN ALOFT...-SHSN WILL BECOME POSSIBLE...MAINLY AT KCMX IN THE AFTERNOON. BY MONDAY EVENING...ADDITIONAL LAKE ENHANCED SNOW MAY BE POSSIBLE AT KSAW AS CONVERGENT NNE FLOW DEVELOPS BEHIND THE DEPARTING MID LEVEL AND SFC LOWS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A LOW PRES TROF EXTENDING FROM NORTHERN ONTARIO ACROSS THE UPPER GREAT LAKES TO THE MID MISSISSIPPI RIVER VALLEY WILL CONSOLIDATE INTO A LOW PRES CENTER OVER SRN LAKE HURON THIS EVENING. AS THIS OCCURS...NRLY WINDS WILL BEGIN TO INCREASE ACROSS LAKE SUPERIOR THIS AFTN AND MORE SO THIS EVENING AND OVERNIGHT. EXPECT NRLY WINDS IN THE 20-30KT RANGE TONIGHT WITH THE STRONGEST WINDS OVER THE E HALF OF THE LAKE. IT`S NOT OUT OF THE QUESTION THAT SOME GALE FORCE GUSTS COULD OCCUR...BUT SINCE THERE IS A LACK OF COLD AIR ADVECTION TO INCREASE MIXING...WILL HOLD OFF ON ANY MENTION OF GALES. PROGRESSION OF THE MAIN WEATHER SYSTEMS WILL SLOW TO A CRAWL TUE THRU FRI. WITH LOW PRES TO THE E AND HIGH PRES TO THE W...N TO NW WINDS WILL BE THE RULE TUE THRU FRI WITH THE STRONGEST WINDS REMAINING OVER THE E HALF OF LAKE SUPERIOR. OVERALL...AFTER TUE...WINDS SHOULD GENERALLY BE IN THE 15-25KT RANGE OVER THE E AND 10-20KT OVER THE W. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...JLB MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 556 AM CST MON NOV 24 2008 .UPDATE... UPDATED FOR AVIATION DISCUSSION BELOW. && .DISCUSSION... /ISSUED 120 AM CST MON NOV 24 2008/ SHORTWAVE TROUGH OVER SOUTHERN CANADA...EXPECTED TO DIVE SOUTH OVER THE WESTERN GREAT LAKES TODAY. CLOUDS WILL THICKEN BACK OVER THE FORECAST AREA...WITH STEEP LAPSE RATES ASSOCIATED WITH CAA. EXPECT SOME SCATTERED SNOW SHOWERS TO DEVELOP OVER THE EASTERN TWO THIRDS OF THE CWA. CLOUDS AND SNOW FLURRIES ARE EXPECTED TO LINGER OVER WEST CENTRAL WISCONSIN EARLY TONIGHT. THE LATEST WATER VAPOR SATELLITE LOOP SHOWED EDGE OF LOW CLOUDS OVER NORTHERN MN. PREVIOUS MODELS AND FORECAST THINKING ON TRACK WITH THIS FEATURE. UPPER RIDGE BUILDS OVER THE UPPER MIDWEST DURING THE REMAINDER OF THE PERIOD THROUGH THURSDAY. MODELS ARE HINTING AT LONGWAVE TROUGH DEVELOPING AND CARVING OUT ACROSS THE GREAT LAKES BY FRIDAY. THE EUROPEAN MODEL APPEARS TO BE THE MOST AGGRESSIVE OF THE LATEST MODELS. THE GFS IS ALSO SHOWING SIGNS OF DEVELOPING A WAVE OVER THE AREA. THIS WILL BEAR WATCHING...AND MAY HAVE TO INTRODUCE SOME LIGHT PRECIP THANKSGIVING NIGHT AND FRIDAY. TEMPS TODAY...SHOULD WARM AHEAD OF THE TROUGH. SFC WINDS SHOULD INCREASE TEMPS TO WARM INTO THE MIDDLE TO UPPER 30S...BEFORE THE COLD AIR SETTLES IN THIS AFTERNOON. TEMPERATURES WERE NOT THAT COLD ACROSS SOUTHERN CANADA...SO TEMPS EXPECTED TO MODERATE BACK INTO THE MIDDLE 30S TO LOWER 40S BY THANKSGIVING DAY. && .AVIATION.../12Z TAF ISSUANCE/ ABUNDANT MOISTURE FROM SUNDAY EVE PRECIP...PLUS LIGHT WINDS AHEAD OF TROUGH...HAVE ENABLED LARGE BATCH OF IFR CIGS TO DEVELOP IN WISC. WESTERN EDGE PROBABLY JUST A FEW MILES WEST OF KEAU. LATEST RUC INDICATES THIS WILL MOVE OUT DURING THE MID MORNING...AND LOOP OF 11-3.9 SATELLITE IMAGERY SUGGESTS AN EVER SO SLIGHT EASTWARD PROGRESSION NORTH OF KEAU. THUS FORECAST DEPICTS SCATTERING OUT AT KEAU AROUND 15Z. MEANWHILE...CIGS AROUND 4K TO 5K FEET IN NRN MN HAVE MOVED FROM CANADA... PINWHEELING AROUND LOW IN NWRN ONTARIO. FIRST WAVE OF CLOUDS HAS SHOWN EROSION ON ITS WESTERN EDGE BETWEEN KFFM AND KGFK... BUT A MORE EXPANSIVE AREA WAS ENTERING NERN ND. GFS AT 06Z CONTINUES TO DO AN EXCELLENT JOB OF REPRESENTATING THIS. BUFKIT SHOWS STEEP LAPSE RATES AND MORE EXPANSIVE MOISTURE THAT WILL MOVE ACROSS EAST CENTRAL MN INTO WISC DURING THE AFTERNOON. SNOW SHOWERS EXPECTED AT ALL SITES EXCEPT KRWF... WITH GREATEST POSSIBILITY OF VSBY RESTRICTIONS AT KMSP...KRNH AND KEAU. MAYBE KSTC TOO. SOUNDING ALSO SUGGESTS GUSTY NW WIND AS WELL BEFORE SFC RIDGE MOVES IN LATER THIS EVENING. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JVM/TDK mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 1221 AM EST TUE NOV 25 2008 .SYNOPSIS... LOW PRESSURE AND A COLD FRONT...WITH WET SNOW AND RAIN...WILL MOVE THROUGH THE REGION TONIGHT...AND TUESDAY. ANOTHER SHOT OF COLD AIR MID WEEK WILL BRING BACK LAKE EFFECT SNOW SHOWERS. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... UPDATED AT 1135 PM... BASED ON SNOW ACCUMS ACRS NRN ONEIDA...UPGRADED ADVISORY TO WARNING FOR 6-10 INCHES. ACRS THE TWIN TIERS...MOST OF THE SNOW IS NOW CONFINED TO HIGHER ELEVATIONS..WITH RAIN IN THE VLYS WHERE THERE HAS BEEN LTL SNOW ACCUM. TONED DOWN THE SNOW AMTS ACRS THE TWIN TIERS...WITH 2-4 INCHES AT HIGHEST ELEVATIONS...AND <1 INCH IN THE VLYS. WE MAY BE ABLE TO DROP THE ADVISORIES FOR MUCH OF THE AREA WITH THE EARLY MRNG UPDATE. PREV BLO... AS OF 9 PM EST... PCPN CONTINUING ACRS CWA THIS EVNG IN DIFFLUENT REGION OF STORM WRAPPING UP OVR THE GREAT LKS. MAIN PCPN AREA LIFTING INTO ERN SXNS OF CWA AT THIS TIME WITH ANOTHER BATCH BHND IT ACRS CNTRL PA. THUS FAR...1-3 INCHES OF SNOW HAS OCCURRED ACRS MOST OF THE REGION. HIGHEST ELEVATIONS HV SEEN TOTALS CLOSER TO 3 INCHES TONIGHT. DEEPEST VALLEYS REPORTING EITHER RAIN OR RA/SN MIX WITH JUST WET CONDS AND NO ACC/S WITH A COUPLE INCHES IN MID- ELEVATIONS. AS SNOW WINDS DOWN FOR SEVERAL HRS TONIGHT...EXPECT -DZ OR FLURRIES FOR A TIME. HWVR...NEXT BATCH MVS IN BY MIDNIGHT AND CUD BRING SOME HEAVIER SNOW AND MORE ACCUMS BY MRNG. SEVERAL ISSUES TO DEAL WITH TONIGHT REGARDING UPDATE. TEMPS INITIALLY CRASHED WITH ONSET OF PCPN THIS AFTN WITH MANY LOCATIONS FALLING FM L40S TO NR FREEZING WITHIN AN HR OR TWO. AT THE SAME TIME...DWPTS CLIMBED TO NR FRZG FROM THE TEENS. THIS HIT ARND EVENING RUSH HR WITH ROAD SFC TEMPS DROPPING TO BLO FRZG. SNOW- COVERED RDS WERE PREVALENT ACRS GOOD PART OF TWIN TIERS. AS STORM SYSTEM HAS WOUND UP...LLJ HAS INTENSIFIED WITH KBGM VWP INDICATING 50KTS AT 4KFT AS OF THIS TIME. AS THIS JET PULLS IN WARMER AIR LATE TONIGHT...SOME LOCATIONS WILL SEE A MIX OR CHG OVR TO RAIN. DEEPEST VALLEYS MAY SEE ALL RAIN FOR A TIME TONIGHT AS WARM AIR SURGES IN FM THE SOUTH. THIS WL LIKELY IMPACT ERN ZONES THE MOST WHERE WINTER STORM WARNING IS IN EFFECT. LATEST RUC APPEARS TO HV CAUGHT UP WITH CURRENT CONDS WHEN COMPARED TO LATEST AIRCRAFT SNDGS. 00Z RUC SOLN INDICATES 925MB TEMPS WARM ABV 0C ACRS WYOMING/LACKAWANNA VALLEYS AND INTO WRN CATSKILLS AFT MIDNIGHT AND THRU DAYBREAK. BOTH NAM/RUC KEEP H8 TEMPS BLO FRZG ACRS ERN ZONES TONIGHT. THIS WUD INDICATE A RAIN/SNOW MIX IN VALLEYS WITH POSSIBLY ALL RAIN IN THE DEEPEST VALLEYS ACRS THE EAST. AT HIGHEST ELEVATIONS ABV 2KFT EXPECT ALL SNOW TONIGHT AND SNOW AMNTS OF 6-10 INCHES IN THESE AREAS. BUFKIT PROFILES INDICATE WARMING ALOFT THRU APPROX 12Z BFR COLUMN COOLS AGAIN AS FNT GOES THRU. THIS MAKES SNOWFALL FCST EXTREMELY DIFFICULT FOR TONIGHT. HV STAYED THE COURSE WITH CURRENT ADVISORIES/WARNINGS IN PLACE THRU NOON TUESDAY. WITH 2-3 INCHES HAVING ALREADY FALLEN ACRS GOOD PART OF THE FA...FEEL ANOTHER 2-3 DEFINITELY DO-ABLE ACRS TWIN TIERS AND HIGHER TERRAIN OF NEPA. AS MORE PCPN MVS UP FROM PA...EXPECT SNOW TO BCM MORE PREDOMINANT AGAIN LATE TONIGHT IN HEAVIER PCPN RATES. FURTHER EAST WILL LEAVE WARNING AS IS. WILL TRY TO HIT THE TERRAIN DIFFERENCES HARDER AS IT APPEARS THIS AREA WILL BE MOST AFFECTED BY ELEVATION SNOWS. RMNDR OF FCST WILL BE UNCHANGED. UPDATED PRODUCTS WILL BE ISSUED SHORTLY. PREV DISCUSSION... SNOW BARRELING INTO THE CWA. NO SIGN OF RAIN YET. TEMPS FALLING WHILE DEWPOINTS THAT WERE IN THE TEENS ARE RISING TO AROUND 30. WARMER AIR WILL SLOWLY MOVE IN FROM THE SOUTH AND ALOFT TONIGHT. RAIN SHOULD MIX WITH THE SNOW THIS EVENING...ESPECIALLY AT THE LOWEST ELEVATIONS OF THE CWA WHICH IS THE FINGER LAKES. ALSO THE BEST QPF WILL BE IN NE PA AND THE EAST SO HAVE LEFT THE FINGER LAKES OUT OF THE WINTER WEATHER ADVISORY. DELAWARE AND OTSEGO WITH MUCH OF THE AREA OVER 1K FT ELEV WILL HAVE THE MOST QPF AND SNOW. THE HIGHEST ELEVATIONS COULD HAVE A FOOT OF SNOW. FOR THESE 2 ZONES WENT WITH A WINT WX WARNING. REST OF CWA IN AN ADVISORY. WITH THE WARMER AIR AT THE SFC THE HIGHEST SNOW AMOUNTS WILL BE AT THE HIGHEST ELEVATIONS AGAIN. IN THE VALLEYS IT WILL BE WET SNOW OR A MIX. LOW LEVELS WILL BE JUST ABOVE FREEZING SO LITTLE CHANCE OF FREEZING RAIN. SLIGHTLY WARMER AIR WILL COME IN AT 925MB RIGHT WITH THE FRONT SO A BETTER CHC OF RAIN OR MIXED LATE TONIGHT AND TUESDAY MORNING. THE FRONT WILL SLOW AS IT MOVES THROUGH TUESDAY AM AS THE UL LOW CUTS OFF AND DEEPENS. WITH THE LL TEMPERATURES JUST ABOVE FREEZING CONFIDENCE ON SNOW AMOUNTS IS MODERATE. A FEW DEGREES ONE WAY OR THE OTHER COULD MAKE A DIFFERENCE OF SEVERAL INCHES OF SNOW AT THE GROUND. && .SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/... PRECIP WILL COME TO AN END AS THE COLD FRONT GOES THROUGH AND THE SFC LOW STALLS OVER WRN NY WHILE THE UL LOW CLOSES OFF. THE BEST CHCS DURING THE AFTN WILL BE IN THE FAR NW CWA WHERE BETTER SYNOPTIC MOISTURE IN THE WRAPAROUND. THIS WILL CONTINUE INTO WEDNESDAY. THE MODEL TRENDS FOR THE EVOLUTION OF THE STACKED LOW IS KEEP IT HERE LONGER AND FURTHER SOUTH. THE LOW IS EXPECTED TO MOVE INTO PA TUESDAY THEN LIFT SLOWLY NORTH INTO SE ONTARIO LATE WED. THE LL FLOW STARTS OUT OF THE WEST THEN FINALLY SHIFTS TO THE NW WED NGT OR THU. THROUGH THE WHOLE SHORT TERM 850 TEMPS ONLY MARGINAL SO NO DECENT STRICTLY LAKE EFFECT IS EXPECTED. && .LONG TERM /FRIDAY THROUGH MONDAY/... UL TROF WILL REMAIN FIXED FROM THE UPPER PORTIONS OF QUEBEC AND ONTARIO DOWN THROUGH THE MID ATLANTIC AND OHIO VALLEY REGIONS. A VIGOROUS WAVE ROTATES THROUGH THE FLOW ON FRIDAY, FOLLOWED BY WEAKER SHOTS OF ENERGY SATURDAY AND SUNDAY. WILL CONTINUE TO FORECAST BELOW NORMAL TEMPS AND UNSETTLED CONDITIONS. && .AVIATION /05Z TUESDAY THROUGH SATURDAY/... AN EARLIER THAN EXPECTED TRANSISTION FROM SNOW TO RAIN HAS ALLOWED VISIBILITIES TO SIGNIFICANTLY IMPROVE ACROSS THE MAJORITY OF OUR TERMINALS. THE HIGHER ELEVATION BGM TERMINAL REMAINS IN IFR RESTRICTIONS DUE TO MODERATE SNOW. CEILINGS WILL RANGE FROM 500 TO 1500 FEET THROUGH THE OVERNIGHT HOURS. AS TEMPERATURES DROP OFF AGAIN EARLY TUESDAY MORNING, WE COULD SEE ANOTHER ROUND OF SNOW SHOWERS WITH REDUCED VISIBILITIES. OUTLOOK... TUESDAY NIGHT AND WEDNESDAY...MVFR/IFR CONTINUES WITH SNOW SHOWERS. THURSDAY...BACK TO LAKE EFFECT SNOW AND NW FLOW. MVFR NORTHERN NY TERMINALS AND VFR ELSEWHERE. FRIDAY...MOSTLY VFR WITH POSSIBLY SOME LINGERING LES UPSTATE NY. SATURDAY...MVFR IN SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR PAZ038>040- 043-044-047-048-072. NY...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NYZ022>025- 036-037-044-045-055-056-062. WINTER STORM WARNING UNTIL NOON EST TODAY FOR NYZ009-046-057. && $$ SYNOPSIS...TAC NEAR TERM...PVN SHORT TERM...TAC LONG TERM...DJP AVIATION...DJP/JML ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 1039 PM EST MON NOV 24 2008 .SYNOPSIS... A COLD FRONT ASSOCIATED WITH LOW PRESSURE NEAR THE GREAT LAKES REGION WILL PUSH THROUGH THE AREA LATE TONIGHT AND OFFSHORE TUESDAY MORNING. HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE GULF COAST STATES LATER TUESDAY THROUGH THURSDAY THEN SLIDE OFFSHORE FRIDAY. ANOTHER FRONTAL SYSTEM IS EXPECTED TO AFFECT THE AREA INTO THE WEEKEND. && .NEAR TERM /THROUGH TUESDAY/... MADE SOME MINOR TWEAKS TO POPS AND TEMPS OVERNIGHT PER CURRENT TRENDS. SEEING TWO DISTINCT AREAS OF PRECIP ATTM...ONE OFFSHORE THE CENTRAL AND SRN OBX ASSOCIATED WITH PREFRONTAL LOW LVL CONVERGENCE. THE OTHER IS THE DENSER BAND OF PRECIP THAT HAS REMAINED MOSTLY W OF THE AREA THUS FAR...WHICH IS OCCURING JUST AHEAD OF THE MAIN FRONTAL BOUNDARY STILL IN WRN PART OF THE STATE AS OF 3Z. WENT AHEAD AND RAISED FAR NW PART AND CENTRAL/SRN COASTAL WATERS TO CATEGORICAL POPS PER TRENDS OF THESE PRECIP REGIONS WHICH IS ALSO IN AGREEMENT WITH LATEST SHORT TERM MODEL GUIDANCE. OTHERWISE HAVE LIKELY ELSEWHERE...AND GENERAL THINKING IS THAT MOST EVERYWHERE SHOULD MEASURE WITH AROUND 1/10-1/4 INCH EXPECTED ON AVERAGE...PSBLY SLIGHTLY MORE NW/N PART WHERE DEEPEST MOISTURE LIES. MAIN PCPN EXPECTED TO MOVE THRU THE AREA BTWN 5-10Z THEN BEGIN MOVING OFFSHORE TOWARDS TUE MORNING. TEMPS HAVE BEEN CHALLENGING TONITE AS A CLOUD MINIMUM AFFECTED MUCH OF THE SRN CWA EARLIER THIS EVENING ALLOWING TEMPS TO FALL QUICKLY TO FORECASTED MINS. THEY HAVE SINCE STABILIZED OR EVEN ROSE AS CLOUDINESS IS INCREASING. OVERALL EXPECTING U40S-L50S MOST LOCATIONS REST OF NITE. DRY AIR WILL FILTER INTO THE REGION BEHIND THE FRONT TUE MORNING AS THE SHOWERS PUSH OFF THE COAST. A STRONG VORT MAX WILL PUSH THROUGH IN THE AFT...BUT THE AIRMASS WILL BE TOO DRY TO SUPPORT CLOUDS LET ALONE PRECIP. THE MIXING WILL SUPPORT BREEZY WNW WINDS AROUND 15 MPH. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... STRONG SUBSIDENCE WILL KEEP SKIES CLEAR TUE NT...AND WITH LOWERING TD WILL SEE TEMPS DROP FAST AFT MIDNIGHT. THE WINDS WILL REMAIN UP FOR THE BULK OF THE NIGHT...BUT IF WINDS DROP OFF TOWARDS DAYBREAK COULD SEE TEMPS BOTTOM OUT INTO THE 20S. EXPECT TEMPS TO REMAIN ABV FREEZING FOR THE MAJORITY OF THE NIGHT...WITH A FAST DROP AROUND SUNRISE. THE THICKNESSES WILL START TO INCREASE WED/WED NT AS THE TROF MOVES OFF TO THE NE...WITH DAYTIME HIGHS INCREASING. WILL SEE ANOTHER COLD NIGHT AS CALM WINDS AND LOW TD SUPPORT FREEZING TEMPS AGAIN. && .LONG TERM /THURSDAY THROUGH MONDAY/... LOOK FOR A COMFORTABLE AND SUNNY DAY ON THANKSGIVING WITH TEMPS IN THE UPPER 50S AND SUNNY SKIES. HEIGHTS WILL CONTINUE TO RISE FRI...WITH SFC HIGH PRESSURE SLIDING OFFSHORE. WENT PRETTY CLOSE TO HPC...WHO FAVORED BLEND OF GFS/ECMWF. GFS IS STILL MUCH QUICKER WITH SYSTEM SAT. HPC PROGS HAVE SFC LOW OVER THE TN VALLEY SATURDAY MOVING NORTHEASTWARD OFF THE COAST SUNDAY...WITH ASSOCIATED COLD FRONT PUSHING THROUGH EASTERN NC OVERNIGHT SATURDAY. ONLY REAL CHANGE TO EXTENDED WAS TO BRING POPS IN A LITTLE EARLIER FRIDAY EVENING. TEMPS THROUGH THE PERIOD GRADUALLY WARMING AHEAD OF THE SYSTEM WITH HIGHS CLOSER TO NORMAL VALUES...UPPER 50S/LOW 60S BY SATURDAY. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... VFR WILL HOLD WITH INCREASING CLOUDS THIS EVENING...THEN STILL EXPECT PERIOD OF MVFR CIGS/VSBYS OVERNIGHT WITH PCPN SHIELD ALONG AND AHEAD OF FRONT. CLEARING EXPECTED BY LATE MORNING TUE. VFR CONDITIONS EXPECTED TO PREVAIL TUE NIGHT-FRI WITH HIGH PRES BUILDING IN. MVFR CONDITIONS PSBL AGAIN WITH NEXT FRONTAL SYSTEM ON SAT. && .MARINE... MODELS HAVE NOT BEEN HANDLING WINDS VERY WELL AND IN FACT HAVE BEEN WELL OVERDONE OUTSIDE OF THE RUC. THINK THE NWP GUIDANCE IS NOT CAPTURING A BROAD TROUGH OF LOW PRESSURE JUST OFF THE COAST ATTM WHICH IS ALLOWING A MUCH WEAKER GRADIENT THAN ANTICIPATED. HOWEVER...AS THE FRONT OVER THE WRN PART OF THE STATE NEARS THAT WILL CHANGE AND STILL THINK S/SW WINDS WILL RAMP UP. GALES LOOK MARGINAL BUT DID NOT FEEL COMFORTABLE DOWNGRADING JUST BEFORE THE EVENT IS EXPECTED TO PEAK (6-15Z) SO KEPT HEADLINES IN TACT FOR GUSTS. DID BACK OFF WINDS/SEAS INITIALLY THO BASED ON CURRENT OBS. FRONT SHOULD PUSH OFFSHORE TUE MORNING WITH SW BECOMING W WINDS MOSTLY IN THE 15-25KT RANGE EXCEPT OUTER PORTION OF CENTRAL/SRN WATERS A LITTLE HIGHER. CAA WILL LIKELY KEEP SCA CONDITIONS OVER OUTER WATERS INTO TUE NIGHT. CONDITIONS IMPROVE WED-THU WITH HGIH PRES BUILDING IN. LOW CONFIDENCE FCST FOR FRI-SAT DUE TO MODEL TIMING DIFFERENCES. WENT WITH HPC FCST OF SLOWER FRONTAL MOVEMENT ON SAT...BUT GFS AND ECWMF ARE TRENDING TO FASTER SYSTEM ON FRI NIGHT. WW3 LOOKS REASONABLE FOR SEAS THROUGH THU...THEN TOO HIGH FOR FRI-SAT AS GFS IS INDICATING FASTER MOVEMENT OF FRONTAL SYSTEM. HOWEVER...WILL NEED TO MONITOR UPCOMING LONG PERIOD ELY SWELL EXPECTED THANKSGIVING INTO THE WEEKEND GIVEN SYSTEM DVLPG IN CENTRAL ATLC NEAR 32N50W. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EST TUESDAY FOR AMZ130-135-150. GALE WARNING FROM 4 AM TO 11 AM EST TUESDAY FOR AMZ152-154-156- 158. && $$ SYNOPSIS...MW/SJ NEAR TERM...MW/SJ SHORT TERM...SJ LONG TERM...CQD AVIATION...JBM MARINE...JBM/MW nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 745 PM EST MON NOV 24 2008 .SYNOPSIS... A LOW PRESSURE SYSTEM OVER THE OHIO VALLEY WILL STRENGTHEN AS IT REACHES UPDATE NEW YORK ON TUESDAY...WHILE A SECONDARY LOW DEVELOPS AND MOVES OFF OF THE MID ATLANTIC COAST. MAINLY SNOW WILL FALL OVER NORTHERN SECTIONS WITH MOSTLY RAIN IN THE SOUTH THROUGH TONIGHT...WITH MIXED PRECIPITATION IN BETWEEN CHANGING BACK TO SNOW SHOWERS ON TUESDAY MORNING AS THE COLDER AIR WRAPS BACK AROUND TO THE SOUTH. AFTERWARDS...COLD...NORTHWESTERLY OVER-LAKE FLOW WILL KEEP SNOW SHOWERS IN THE FORECAST FOR MUCH OF THE REGION THIS WEEK WITH AREAS OF HEAVIER LAKE EFFECT AND OROGRAPHICALLY ENHANCED SNOWS POSSIBLE ACROSS THE WESTERN ALLEGHENIES. && .NEAR TERM /UNTIL 11 PM THIS EVENING/... PRECIP SHIELD HAS REACHED THE CENTRAL MOUNTAINS WITH LIGHT SNOW AND SOME SLEET FALLING HERE AT NWS CTP THIS HOUR. TRANSITION ZONE NOT FAR AWAY WITH MIXED PRECIP AT KFIG AND KDUJ...AND COLD RAIN AT KJST AND KAOO WITH 33F AIRTEMP AND 28F DEWPOINTS. CURRENT ADVISORIES SEEM WELL PLACED FOR THIS EVENING WITH LITTLE IN THE WAY OF CHANGES. 09Z SREF PTYPE PROBS CONT TO FAVOR SNOW MIXED WITH SLEET FROM CENTRAL MOUNTAINS NORTHWARD...WITH PRIMARILY SNOW FROM I80 NORTHWARD. SREF INDICATES CATEGORICAL PROBS OF .5" OR GREATER IN 12 HOURS FROM 18Z MON TO 06Z TUE. A FEW PLUMES SUGGEST THE POTENTIAL FOR MORE THAN 4 INCHES FROM WILLIAMSPORT NORTHWARD TONIGHT. MODEL FORECASTING SOUNDINGS ARE PREDOMINATELY "SNOW" SOUNDINGS AFTER PRECIP ARRIVES...WITH DYNAMIC COOLING TO THE WET BULB TEMPERATURES CREATING ISOTHERMAL SOUNDINGS BELOW FREEZING TO NEAR THE SURFACE FROM CENTRAL MOUNTAINS NORTHWARD. UNLIKE LAST YEAR WHICH WAS THE "WINTER OF THE WARM LAYER ALOFT" FOR MUCH OF CENTRAL PA... DIFFICULT TO FIND A WARM LAYER ALOFT WITH THIS SYSTEM. A MESSY EVENING COMMUTE IS AHEAD FOR MUCH OF CENTRAL AND ALL OF NORTHERN PA AS THE ONSET OF PRECIPITATION IS ILL-TIMED. FURTHER NORTH... PRIMARILY SNOW WILL CONTINUE WITH MANY AREAS LIKELY RECEIVING 3 OR 4 INCHES OF SNOW THROUGH LATE TONIGHT. TRANSITION BACK TO SNOW SHOWERS WILL OCCUR AFTER MIDNIGHT AS COLDER AIR WRAPS BACK AROUND INTO CENTRAL PA AS COASTAL LOW DEVELOPS. EXPECT WESTERN AND CENTRAL SECTIONS TO BE CHANGED OVER BEFORE 10Z WITH EASTERN SECTIONS LAGGING A BIT BEYOND THAT TIMEFRAME. && .SHORT TERM /11 PM THIS EVENING THROUGH 6 AM TUESDAY/... TRANSITION WILL CONTINUE ACROSS THE CENTRAL MOUNTAIN REGION TONIGHT...WITH I-80 FAIRLY CLOSE TO THE RAIN/SNOW LINE AS SUGGESTED BY LATEST GUIDANCE AND RUC13 FORECASTS OF WET BULB ZERO. THE LOWER SUSQ VALLEY SHOULD BE PRIMARILY RAIN. THE HIGHER ELEVS OF SULLIVAN/SCHUYLKILL CO POSE THE GREATEST FCST CHALLENGE FOR INTO TONIGHT...GIVEN THE ELEVATION PTYPE DEPENDENCE. HAVE HELD OFF AN ANY HEADLINES AT THIS POINT WITH ACCUMS OF 1-3 INCHES MENTIONED. WILL LET THE DAY SHIFT CONSULT THE LATEST GUID AND MAKE THE FINAL DECISION ON ANY FLAGS FOR TNT. THE CLD/OCCLD FNT WILL SWEEP ACROSS THE REGION LATE TONIGHT...ACCOMPANIED BY A GUSTY WIND SHIFT TO THE W/SW. THE HIGH RESOLUTION NAM/WRF DEPICTS A MORE ROBUST DRY SLOT IMMEDIATELY BEHIND THE FRONT...AND SOUNDINGS SHOW SOME DRYING ALOFT. THIS SHOULD RESULT IN MORE SHOWERY/LIGHTER PCPN AFT 06Z ESP ACROSS THE WEST. AS THE UPPER LVL TROF TRANSITIONS FROM A NEUTRAL TO A SLIGHTLY NEG TILT...ERN PA MAY PICK UP SOME ADDNL MOD TO HEAVY QPF AS MDLS HINT AT A SECONDARY WAVE DEVELOPING ALONG THE TRAILING CLD FNT. THIS IS OFTEN THE CASE AS THE AMPLIFIED NATURE OF THE LW TROF LEADS TO A SLOWER EWD FNTL PROGRESSION. THE ANOMALOUS H5 LOW IS FCST TO ESSENTIALLY MOVE OVERHEAD ON TUE...ACCOMPANIED BY VERY COLD TEMPS ALOFT AND STEEP MID LVL LAPSE RATES. THIS SHOULD RESULT IN NUMEROUS SNOW SHOWERS WITH LOCALLY HEAVY SQUALLS ACROSS MUCH OF THE AREA. THE ENTIRE STORM SYS BECOMES VERTICALLY STACKED AS IT RETROGRADES NWWD FROM THE LWR LAKES INTO SRN ONTARIO BY WED. THIS SET UP SHOULD FAVOR MORE LAKE EFFECT/ENHANCED AND OROGRAPHIC SNOWS ACROSS THE WESTERN ALLEGHENIES...WITH SEVERAL INCHES OF ACCUMULATION POSSIBLE BY WED NGT. && .LONG TERM /TUESDAY THROUGH MONDAY/... CHALLENGES WITH THE EXTENDED FORECAST RESIDE WITH LES SNOW MACHINE AND FAVORED ORAGRAPHIC LIFT SNOW REGIONS SEEING SNOW LATE TUE EVE THRU EARLY THUR. LCL WRF-ARW/NMM PAINT MID-LVL VORT ACROSS ALLEGHENIES TUE AFTN...LIFTING NORTHEAST TUE EVE. LCL MODELS SUGGEST AN AREA OF DEFORMATION SNOW MAY PERSIST ACROSS SUSQ-VALLEY TUE AFTN. ATTM THINKING ACCUMS SHUD REMAIN SUB-ADVISORY CRITERIA...HOWEVER THIS REMAINS A CONCERN. NEGATIVELY TILTED 500MB VORT...SENDS A WEAK VORT MAX ARND TROUGH AXIS TUE...ALLOWING COASTAL LOW TO DEV OFFSHORE OF LONG ISLAND/CAPE COD VICINITY. THIS SOLUTION WOULD FAVOR QUICKLY PULLING LLVL MOISTURE EAST OF THE SUSQ-VALLEY BY 21Z TUE. DRY WEDGE QUICKLY PUSHES INTO CENTRAL PA AFT 18Z AS FLOW SLOWLY BECOMES WESTERLY/NORTHWESTERLY. DENDRITIC GROWTH GRADUALLY LOWERS ACROSS ALLEGHENIES AS COLD AIR STEADILY POURS INTO THE WESTERN MOUNTAINS OF PA TUE EVE. 1000-850MB LAYERED RH SATURATES ARND 00Z WED...WITH A NARROW WEDGE OF OMEGA IN THE CROSS-HAIRS OF SEVERAL PROFILES. THIS SHUD KICK THE SNOW MACHINE INTO HIGH GEAR THRU EARLY THANKSGIVING DAY. MID-LVL VORT SLOWLY LIFTS NORTHEAST THUR INTO QUEBEC...ALLOWING FLOW TO BACK TO WESTERLY IN THE LLVL/S. THIS FEATURE WOULD PUSH ANY LINGERING LES NORTH OF PA INTO NEW YORK TOWARDS END OF THE WEEK. OPERATIONAL MODELS KEEP 850MB TEMPS WELL BELOW ZERO...COUPLED WITH A 534DM THICKNESS SUPPORT PRECIP AS SN. OPERATIONAL GFS PRODUCES A BROAD SFC RIDGE FOR THE MID-ATLANTIC FRI...HOWEVER FEEL IT WILL STRUGGLE TO MIX OUT LLVL MOISTURE. CLOUDS MAY LINGER THRU WEEKEND. ENSEMBLES SUGGEST A HIGH AMPLITUDE RIDGE BUILDING ACROSS THE WESTERN CONUS...FAVORING A PERSISTENT TROUGHING PATTERN FOR THE EASTERN US. SEVERAL MEMBERS TRY TO DEVELOP A VERY WEAK SOUTHERN STREAM SHORTWAVE SAT. THEN BRING IT NORTH ARND TROUGH AXIS FOR THE UPCOMING WEEKEND. TIMING AND PLACEMENT HAVE A LOW CONFIDENCE. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... WIDESPREAD SNOW...RAIN...SLEET...AND FREEZING RAIN THIS EVENING... WITH CONDITIONS MAINLY IN THE MVFR AND IFR RANGE. CONDITIONS WILL IMPROVE SOME LATER...AS TEMPS COME BACK UP...AND STEADY PCPN TAPERS OFF. TEMPS DID WARM TODAY...BUT THICK CI HELD AMT OF HEATING DOWN...SO GROUND TEMPS ARE STILL COLD...AND MINOR AMTS OF SNOW STARTING TO CAUSE PROBLEMS. ALSO THE VERY DRY AIR IN PLACE MOST LIKELY HAD A PART TO PLAY IN PCPN TYPE TODAY. ANYWAY...A COLD FRONT WILL PUSH EAST ACROSS PA VERY EARLY TUESDAY. MVFR CIGS AND OCNL MVFR VSBYS IN SHSN WILL BE CONCENTRATED ACROSS THE HIGHER TERRAIN OF WRN AND NRN PENN (TAF SITES KJST AND KBFD). A SECONDARY COLD FRONT PUSHING ACROSS THE REGION TUESDAY NIGHT WILL USHER IN COLDER AIR...WITH MORE WIDESPREAD SNOW SHOWERS AND PERSISTENT MVFR TO IFR CIGS AND VSBYS ACROSS ALL OF CENTRAL AND NWRN PENN. AREAS OF LIFR/VLIFR CIGS/VSBYS WED AND WED NIGHT...WITH SOME IMPROVEMENT IN CONDITIONS SEEN FOR THANKSGIVING DAY AS THE FLOW BECOMES MORE WESTERLY. ANOTHER STORM WITH MIXED PRECIPITATION MAY AFFECT THE AREA FRIDAY INTO SATURDAY. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 5 AM EST TUESDAY FOR PAZ004>006- 010>012-017>019-025>027-037-041-042-045-046-049>053-058. WINTER STORM WATCH FROM TUESDAY EVENING THROUGH LATE WEDNESDAY NIGHT FOR PAZ017-024-033. LAKE EFFECT SNOW WATCH FROM TUESDAY EVENING THROUGH LATE WEDNESDAY NIGHT FOR PAZ004-005-010. && $$ SYNOPSIS...DEVOIR NEAR TERM...DEVOIR SHORT TERM...DEVOIR LONG TERM...BEACHLER AVIATION...DEVOIR/LAMBERT/MARTIN pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1239 AM EST MON NOV 24 2008 .SYNOPSIS... A COLD FRONT WILL REACH OUR AREA FROM THE WEST LATE MONDAY WITH SOME BREEZY CONDITIONS MAINLY MONDAY NIGHT AND TUESDAY IN THE MOUNTAINS. HIGH PRESSURE WILL THEN BUILD ACROSS OUR REGION UNTIL THE END OF THE WEEK WHEN ANOTHER FRONT WILL APPROACH FROM THE WEST. && .NEAR TERM /THROUGH TODAY/... LATEST SAT/RUC ANALYSIS AND 00Z RAOBS SHOW WEAK UPR RDG W/ AXIS FROM MI...THRU THE OHIO VALLEY...TO WRN GULF OF MEXICO. MEANWHILE...A POTENT S/W TROF PROGRESSES ACRS THE UPR MS VALLEY. IN THE LOW LVLS...A WEAK RDG AXIS WAS ANALYZED N-S ACRS THE TN VALLEY...W/ SOME DEEPER MOISTURE TO THE W OVR THE LWR MS VALLEY. DECENT H8-H7 WAA WAS OCCURRING ACRS MUCH OF THE SOUTHEAST STATES...W/ SOME SCT LGT RA SHWRS DEVELOPING INVOF MEMPHIS...TO PADUCAH..TOWARD NASHVILLE. THE LATEST MODELS ARE IN GENERAL AGREEMENT ON THE QPF FROM 00-06Z IN AFOREMENTIONED AREA (W/ THE EXCEPTION OF THE 00Z NAM WHICH SHOWED NONE OF THAT PRECIP.) WITH ALL THAT SAID...LTL CHANGE NEEDED TO POPS FOR THE PERIOD AROUND SUNRISE MONDAY MORNING. MID LVL CLOUDS ARE MOVING INTO THE WRN QUARTER OF THE FA ATTM...AND TEMP HAVE SLOWED DOWN OR STOPPED DECREASING UNDER THE CLOUDS. WITH STRONGER H8 WAA ACRS THE SW MTNS COMMENCING BY 06Z...AND CURRENT TEMPS STILL IN THE MID-UPR 30S...I DID MY BEST TO ADJUST TEMP TRENDS AND MIN TEMPS IN THAT AREA. ALSO...TOP-DOWN METHODOLOGY ON 00Z GUIDANCE RESULTED IN LESS WINTRY PRECIP W/ ONSET DURING THE PRE-DAWN HOURS. HOWEVER...A WINTRY MIX W/ SLEET AN/OR FZRA IS STILL POSSIBLE IN THE SWRN NC VALLEYS WHERE POCKETS OF COLDER AIR MAY STILL BE IN PLACE. QPF SHUD BE TOO LGT TO WARRANT ANY ADVISORY AT THIS TIME. HOWEVER...TRENDS WILL BE CLOSELY MONITORED. THE POTENTIAL FOR WINTRY PRECIP THIS MORNING WILL CONTINUE TO BE MENTIONED IN THE HWO. THE HEAVIER QPF WILL DEVELOP THROUGH THE DAY AS A COLD FRONT APPROACHES FROM THE WEST AND THE 850 MB JET INTENSIFIES THE WARM ADVECTION. THIS 50 KT JET WILL TRAVERSE THE NC MTNS DURING THE AFTERNOON HOURS MONDAY...BUT LIKELY PRODUCE LITTLE MORE THAN BREEZY TO WINDY CONDITIONS ACROSS THE RIDGE TOPS SINCE IT IS EMBEDDED IN WARM ADVECTION FLOW. IN SITU CAD IN PLACE WITH THE ONSET OF PRECIPITATION EAST OF THE BLUE RIDGE WILL KEEP MAXES BELOW MOS VALUES FOR MONDAY AFTERNOON THROUGHOUT THE PIEDMONT...PROVIDED ENOUGH MEASURABLE RAIN FALLS BY EARLY AFTERNOON. QPF AMOUNTS SHOULD RANGE FROM LESS THAN ONE QUARTER OF AN INCH ALONG THE EASTERN FRINGE TOMORROW TO AROUND AN INCH IN THE SOUTHWEST MOUNTAINS. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... AS OF 2 PM SUNDAY...A STRONG SHORTWAVE TROUGH WILL CROSS OUR AREA MONDAY NIGHT AS A CLOSED LOW MOVES JUST SOUTH OF THE GREAT LAKES. SLOWER FRONTAL TIMING IN BOTH THE NAM AND GFS WILL MEAN HIGHER POPS MONDAY EVENING ACROSS OUR AREA. HAVE GONE WITH A COMPROMISE OF LOW END CATEGORICAL. AFTER MIDNIGHT PRECIPITATION WILL END WITH FRONTAL PASSAGE IN THE LEE OF THE MOUNTAINS...WHILE A NORTHWEST FLOW PRECIPITATION EVENT BEGINS IN THE NC MOUNTAINS. FREEZING AND WET BULB ZERO LEVELS DROP TO THE VALLEY FLOORS BY DAYBREAK TUESDAY...BUT WILL LIFT SLIGHTLY DURING THE DAY WITH MEAGER WARMING. THE LATEST GUIDANCE HAS WARMED A FEW DEGREES ABOVE THE PREVIOUS FORECAST...BUT WITH SOME VACILLATION BY THE MODELS...FORECAST TEMPERATURES WILL ONLY BE RAISED A DEGREE OR TWO. UPSLOPE SNOW SHOWERS CONTINUE IN THE NC MOUNTAINS INTO TUE NIGHT...BUT THIS RUN OF THE WETTER AND PREFERRED GFS NOW DECREASE MOISTURE ALONG THE TN BORDER THROUGH THE NIGHT...ENDING THE EVENT BY WEDNESDAY MORNING. A BLEND OF GFS AND SREF QPF...ADJUSTED UP IN FAVORED AREAS...YIELDS SNOWFALL TOTALS OF UP TO FOUR INCHES...WITH THE HIGHEST AMOUNTS IN THE NORTHERN MOUNTAINS. A WINTER STORM WATCH WILL BE ISSUED FOR OUR NORTHERN NC MOUNTAINS FOR MONDAY NIGHT INTO WEDNESDAY MORNING. ADVISORY CRITERIA SNOW ARE EXPECTED SOUTH TO THE SMOKIES...AND ALONG THE NORTHERN BLUE RIDGE. WEDNESDAY AND WEDNESDAY NIGHT FEATURE A DRY SURFACE RIDGE OVER THE COASTAL SOUTHEAST. MOISTURE FROM A DEVELOPING GULF SYSTEM SPREAD NORTHEAST OVER THE TRAILING EDGE OF THE RIDGE...BUT LARGELY APPEARS TO REMAIN SOUTHWEST OF OUR AREA. NOT MUCH WARMING IS EXPECTED IN THE LEE WEDNESDAY AS HEIGHT RISES ARE OFFSET BY A WEAKENING DOWNSLOPE FLOW...HOWEVER MOUNTAIN LOCATIONS WILL SEE A GAIN OF A FEW DEGREES AS COLD ADVECTION ABATES. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 215 PM SATURDAY...LEANED MORE TOWARD HPC THIS FCST. UPPER LOW FINALLY MOVES OFF E COAST THU WITH H5 RIDGE BUILDING OVER AREA WHILE SFC HI SLOWLY MOVES SE DURG DAY. THIS PUTS AREA IN MOIST SE FLOW AND MOISTURE WILL INCREASE FROM THE SW AHEAD OF A SFC WAVE THAT DEVELOPS OVER N GULF STATES THU NIGHT-FRI. EVEN THOUGH GFS TAKES SYSTEM FARTHER S THAN ECMWF...HPC USED A COMPROMISE THAT BRINGS THE SFC WAVE ACROSS N PART OF CWA SAT. WAA AHEAD OF THIS FEATURE WILL KEEP TEMPS MILD WITH SLIGHT CHANCE OF RAIN SHOWERS FRI. POPS INCREASE TO SOLID CHANCE FRI NIGHT. THERE IS ENOUGH UNCERTAINTY BETWEEN MODEL SOLUTIONS ATTM THAT I WILL NOT PAINT A SIGNIFICANT NW FLOW SNOW EVENT OVER MTNS FOR THE WEEKEND. LEANED TOWARD WARMER HPC TEMPS WHICH ARE STILL BELOW AVG BUT STILL ALLOW FOR SOME SNOW OVER HIGHER MTNS FRI NIGHT...THEN AGAIN SAT NIGHT. SYSTEM MOVES E OF AREA AND OFF THE COAST SUN WITH TEMPS COOLING A FEW DEG BEHIND IT. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... VFR STRATOCU DECK CONTINUES TO SPREAD RATHER QUICKLY ACROSS THE WESTERN CAROLINAS EARLY THIS MORNING...AND THIS TREND WILL CONTINUE THROUGH THE MORNING HOURS. MOST LOCATIONS SHOULD SEE A CIG IN THE 035-050 RANGE BY SUNRISE. MVFR CIGS WILL BE POSSIBLE DURING THE DAYTIME HOURS...BUT NUMERICAL GUIDANCE DOES NOT SUPPORT THIS ATTM... SO WE WILL LEAVE RESTRICTIONS OUT OF THE FORECASTS FOR NOW. MOISTURE WILL INCREASE DURING THE DAY AHEAD OF VIGOROUS STORM SYSTEM/COLD FRONT. HOWEVER...THE NEAR SURFACE AIR WILL REMAIN QUITE DRY...AND THIS COULD CAUSE A DELAY IN ONSET OF PRECIP. ADDITIONALLY...MODEL GUIDANCE APPEARS TO BE SLOWING THE PROGRESSION OF THE COLD FRONT. WITH THIS IN MIND...PRECIP TIMING HAS BEEN DELAYED 2-4 HOURS AT ALL TERMINALS. THE MOST LIKELY PERIOD FOR VISBY/CIG RESTRICTIONS ASSOCIATED WITH PRECIP WILL BE AFTER 00Z AT MOST TERMINALS. OUTLOOK...GUSTY NORTHWEST WINDS WILL DEVELOP LATE MONDAY NIGHT THROUGH TUESDAY...WITH SCATTERED SNOW SHOWERS AND OCCASIONAL MVFR CEILINGS POSSIBLY BLOWING UP THE FRENCH BROAD VALLEY TO KAVL. THE NORTHWEST FLOW MOISTURE WILL CONTINUE THROUGH AT LEAST MID WEEK...WITH VERY DRY CONDITIONS OUTSIDE OF THE HIGHER TERRAIN. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...WINTER STORM WATCH FROM THIS EVENING THROUGH WEDNESDAY MORNING FOR NCZ033-049-050. SC...NONE. && $$ SYNOPSIS...DEO NEAR TERM...ARK/HG SHORT TERM...JAT LONG TERM...RB AVIATION...ARK/JDL sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 751 PM CST MON NOV 24 2008 .DISCUSSION... DRY AIR ASSOCIATED WITH THE FRONTAL BOUNDARY SITTING FROM JUST SOUTH OF LRD TO JUST SOUTH OF CRP...AND IS MOVING SOUTH AROUND 15 MPH. THE LINE SHOULD REACH THE RIVER JUST AFTER MIDNIGHT. A FEW LIGHT SHOWERS ARE POSSIBLE AS THE FRONT PASSES...BUT WILL BE FEW AND FAR BETWEEN. FOG SHOULDN`T HAVE ENOUGH TIME TO DEVELOP AHEAD OF THE FRONT. LOWS LOOK ON TRACK FOR RIGHT AROUND 60...DROPPING QUICKLY AFTER THE FRONT PASSES. CURRENT FORECAST HAS ALL THIS COVERED...SO NO UPDATES NEEDED. && .AVIATION... VFR CONDITIONS IN BOTH CIG/VSBY WILL CONTINUE THROUGH TONIGHT WITH TEMPO MVFR IN CIG DUE TO A COLD FRONT MOVING THROUGH THE AREA. VFR CONDITIONS WILL PREVAIL DURING THE DAY ON TUESDAY. WINDS WILL BE LIGHT FROM THE NORTHEAST INCREASING TO MODERATE LATER TONIGHT AND CONTINUING THROUGH TUESDAY. && .MARINE... AT 7 PM BOY020 REPORTED A NORTHEAST WINDS AT 8 KNOTS AND SEAS 3.6 FEET AT 7 SECONDS. WINDS AND SEAS WILL CONTINUE TO INCREASE TONIGHT IN THE WAKE OF A COLD FRONT THAT IS MOVING THROUGH THE COASTAL WATERS OF DEEP SOUTH TEXAS AT THIS TIME. WINDS AND SEAS WILL CONTINUE TO BE JUST BELOW SMALL CRAFT ADVISORY CRITERIA TONIGHT. HIGH PRESSURE WILL BUILD INTO THE AREA ON TUESDAY CAUSING A RELATIVELY DRY AND STABLE AIRMASS WITH WINDS DECREASING ONCE AGAIN. ANOTHER COLD FRONT WILL MOVE THROUGH THE AREA BY LATE FRIDAY CAUSING POSSIBLE SMALL CRAFT ADVISORY CRITERIA FRIDAY NIGHT AND SATURDAY. && .PREV DISCUSSION... /ISSUED 142 PM CST MON NOV 24 2008/ DISCUSSION...CURRENT 18Z VISIBLE SATELLITE IMAGERY AND RUC ANALYSIS SHOWS THE COLD FRONT OVER THE CORPUS CHRISTI CWA WITH 5 TO 10 KTS SURFACE WINDS AHEAD OF THE COLD FRONT. SCATTERED CUMULUS AND STRATOCUMULUS ARA MAINLY LOCATED OVER THE EASTERN HALF OF THE BRO CWA WITH MAINLY CLEAR TO PARTLY CLOUDY SKIES IN THE CENTRAL PORTIONS OF THE CWA. A DECK OF STRATOCUMULUS ENTERING THE WESTERN PORTIONS OF ZAPATA COUNTY. AS THE DAY PROGRESSES THE FRONT WILL APPROACH FROM THE NORTHWEST BRING A SLIGHT CHANCE OF SHOWERS THIS EVENING. A BLEND OF THE ECMWF AND GFS CONTINUES TO BE THE PREFERRED SOLUTION FOR THE GRIDS FOR TEMPERATURE AND PRECIPITATION FOR THE REMAINING OF THE WEEK. IN THE SHORT TERM AFTER THE PASSAGE OF THE FRONT AN UPPER LEVEL RIDGE WILL BUILD OVER NORTHERN MEXICO AHEAD OF A DEEPER TROF OF LOW PRESSURE THAT WILL ENTER THE SW US TOWARD THE LATTER PART OF THIS WEEK. UPPER LEVEL WINDS OVER DEEP SOUTH TEXAS WILL BE NORTHWESTERLY AND THEN WESTERLY AND SOUTHWESTERLY AS THE JET ON THE EASTERN SIDE OF THIS SYSTEM CONTINUES TO TRACK EAST TOWARD THE GULF OF MEXICO BY NEXT WEEKEND. BY WED 06Z SURFACE FLOW WILL BECOME SOUTHEASTERLY AND START INCREASING OUR TOTAL PRECIPITABLE WATER TO A MAX OF AROUND 1.60 BY THE END OF THE WEEK JUST PRIOR TO THE PASSAGE OF THE NEXT FRONT/TROF FROM THE SW US. THE SURFACE NE WINDS EXPECTED TO START SATURDAY MORNING COULD BRING OVERRUNNING PRECIPITATION TO DEEP SOUTH TEXAS WITH SOUTHWESTERLY FLOW ABOVE THE BOUNDARY LAYER. AS THE UNCERTAINTY DECREASES WITH THE AMPLITUDE AND TRACK OF THIS PACIFIC STORM THE GRIDS WILL BE CONTINUOUSLY UPDATED THROUGHOUT THE WEEK. THE 12Z ECMWF HAVE COME IN LINE MORE WITH THE 12Z GFS AND STILL SHOW THE ECMWF HAVING A MORE ABRUPT DROP IN THE DEWPOINTS FOR DEEP SOUTH TEXAS IN COMPARISON WITH THE GFS...HOWEVER...THE GFS DROPS TO LOWER DEWPOINTS THAN THE ECMWF BY MONDAY. BOTH THE NEW GFS AND ECMWF DEWPOINTS ARE HIGHER THAN FROM THE PREVIOUS RUNS. && .BRO WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT: HTTP://WWW.WEATHER.GOV/BROWNSVILLE 64/65 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 142 PM CST MON NOV 24 2008 .DISCUSSION...CURRENT 18Z VISIBLE SATELLITE IMAGERY AND RUC ANALYSIS SHOWS THE COLD FRONT OVER THE CORPUS CHRISTI CWA WITH 5 TO 10 KTS SURFACE WINDS AHEAD OF THE COLD FRONT. SCATTERED CUMULUS AND STRATOCUMULUS ARA MAINLY LOCATED OVER THE EASTERN HALF OF THE BRO CWA WITH MAINLY CLEAR TO PARTLY CLOUDY SKIES IN THE CENTRAL PORTIONS OF THE CWA. A DECK OF STRATOCUMULUS ENTERING THE WESTERN PORTIONS OF ZAPATA COUNTY. AS THE DAY PROGRESSES THE FRONT WILL APPROACH FROM THE NORTHWEST BRING A SLIGHT CHANCE OF SHOWERS THIS EVENING. A BLEND OF THE ECMWF AND GFS CONTINUES TO BE THE PREFERRED SOLUTION FOR THE GRIDS FOR TEMPERATURE AND PRECIPITATION FOR THE REMAINING OF THE WEEK. IN THE SHORT TERM AFTER THE PASSAGE OF THE FRONT AN UPPER LEVEL RIDGE WILL BUILD OVER NORTHERN MEXICO AHEAD OF A DEEPER TROF OF LOW PRESSURE THAT WILL ENTER THE SW US TOWARD THE LATTER PART OF THIS WEEK. UPPER LEVEL WINDS OVER DEEP SOUTH TEXAS WILL BE NORTHWESTERLY AND THEN WESTERLY AND SOUTHWESTERLY AS THE JET ON THE EASTERN SIDE OF THIS SYSTEM CONTINUES TO TRACK EAST TOWARD THE GULF OF MEXICO BY NEXT WEEKEND. BY WED 06Z SURFACE FLOW WILL BECOME SOUTHEASTERLY AND START INCREASING OUR TOTAL PRECIPITABLE WATER TO A MAX OF AROUND 1.60 BY THE END OF THE WEEK JUST PRIOR TO THE PASSAGE OF THE NEXT FRONT/TROF FROM THE SW US. THE SURFACE NE WINDS EXPECTED TO START SATURDAY MORNING COULD BRING OVERRUNNING PRECIPITATION TO DEEP SOUTH TEXAS WITH SOUTHWESTERLY FLOW ABOVE THE BOUNDARY LAYER. AS THE UNCERTAINTY DECREASES WITH THE AMPLITUDE AND TRACK OF THIS PACIFIC STORM THE GRIDS WILL BE CONTINUOUSLY UPDATED THROUGHOUT THE WEEK. THE 12Z ECMWF HAVE COME IN LINE MORE WITH THE 12Z GFS AND STILL SHOW THE ECMWF HAVING A MORE ABRUPT DROP IN THE DEWPOINTS FOR DEEP SOUTH TEXAS IN COMPARISON WITH THE GFS...HOWEVER...THE GFS DROPS TO LOWER DEWPOINTS THAN THE ECMWF BY MONDAY. BOTH THE NEW GFS AND ECMWF DEWPOINTS ARE HIGHER THAN FROM THE PREVIOUS RUNS. && .MARINE...THE 1 PM OBSERVATION FROM BUOY 42020 INDICATED WINDS WERE WEST SOUTHWEST AROUND 4 KTS AND SEAS WERE AROUND 4 FT WITH A PERIOD OF 8 SECONDS. MTRPIL REPORTED AN EAST NORTHEAST WIND AROUND 7 KTS. RELATIVELY QUIET MARINE CONDITIONS OBSERVED TODAY COMPARED THE LAST COUPLE DAYS. CHC FOR SCT SHRAS ARE POSSIBLE THE REST OF THE DAY AS A COLD FRONT CONTINUES TO APPROACH FROM THE NORTH. EXPECT WINDS TO REMAIN LIGHT TO MODERATE AND VARIABLE IN DIRECTION THRU THIS AFTN BEFORE BECOMING NORTHEAST BY THIS EVENING. WINDS SHOULD THEN INCREASE SOMETIME AFTER SUNSET TONIGHT IN THE WAKE OF THE FROPA. A MODERATE NORTHEAST WIND WILL REMAIN THRU THE DAYTIME HRS ON TUESDAY BUT BEGIN TO RELAX BY LATE IN THE DAY AS HIGH PRESSURE TAKES OVER. CONDITIONS LATE TONIGHT THRU TUESDAY COULD APPROACH SMALL CRAFT CONDITIONS...ESPECIALLY IN THE FAR OFFSHORE WATERS AT 20 TO 60 NAUTICAL MILES OFFSHORE. BASED ON LATEST OBS AND GUIDANCE...THINK CAUTION STATEMENT WILL SUFFICE FOR NOW...BUT LATER SHIFT COULD DECIDE IF STRONGER WORDING IS NEEDED. HIGH PRESSURE WILL SHIFT NORTHEAST INTO THE NORTHWEST AND NORTH CENTRAL GULF OF MEXICO ON WEDNESDAY WHICH WILL HELP TO ESTABLISH AN ONSHORE FLOW WITH MODERATE SOUTHEAST WINDS. THIS PATTERN WILL LIKELY THEN HOLD THROUGH THANKSGIVING INTO FRIDAY. CONDITIONS WITH THIS TYPE OF PATTERN MAY RESEMBLE THE SAME CONDITIONS THAT WERE EXPERIENCED THIS LAST WEEKEND WITH CLOUDY SKIES AND SCT SHRAS. ANOTHER POTENTIALLY STRONGER COLD FRONT IS ANTICIPATED TO PASS THROUGH THE LOWER TX COASTAL WATERS LATE FRIDAY OR EARLY SATURDAY. MARINE CONDITIONS IN THE WAKE OF THIS FRONT WILL HAVE THE POTENTIAL TO APPROACH OR EXCEED SMALL CRAFT ADVISORY CRITERIA. SEAS THE REST OF TODAY SHOULD REMAIN FAIRLY STEADY WITH AN INCREASE EXPECTED ONCE THE COLD FRONT PASSES. SEAS WILL REMAIN SLIGHTLY ELEVATED THROUGH TUESDAY BEFORE A SLIGHT DECREASE IS EXPECTED ON WEDNESDAY INTO THURSDAY. BUILDING SEAS ARE ANTICIPATED ONCE AGAIN TO TAKE PLACE POST FRONTAL LATE FRIDAY INTO SATURDAY. && .AVIATION...VSBL SATL IMAGERY SHOWS CU DEVELOPMENT ACROSS THE CWA THIS AFTN. CLD BANDS ASSOC A COLD FRONT APPROACHING FROM THE NORTH FROM AROUND CRP TO LRD. EXPECT CLDS TO HANG ON THROUGH TONIGHT. SOME SCT SHRAS COULD BE POSSIBLE WITH THE FROPA. A LIGHT AND VARIABLE WINDS IS EXPECTED THIS AFTN BEFORE BECOMING NORTHEAST BY THIS EVENING. LIGHT TO MODERATE NORTHEAST WINDS WILL CONTINUE THROUGH TUESDAY. EXPECTING VFR CONDITIONS TO PREVAIL THE NEXT 24 HRS. .PREV DISCUSSION... /ISSUED 940 AM CST MON NOV 24 2008/ DISCUSSION... THERE IS A CHANCE FOR SCT SHRAS LATER TODAY AS A COLD FRONT APPROACHES FROM THE NORTH. THE FRONT SHOULD CLEAR THE AREA BY EARLY TUESDAY MORNING. A LIGHT SOUTHERLY WIND TODAY WILL BACK NORTHEASTERLY ON TUESDAY AND REMAIN MODERATE THROUGH TUESDAY AFTN. ECMWF...NAM...AND GFS ARE IN GOOD AGREEMENT IN THE SHORT TERM DEPICTING WELL A WEAK FRONTAL PASSAGE FOR TONIGHT. IN THE EXTENDED RANGE THE ECMWF SHOWS A SHARP DECREASE IN DEWPOINTS AFTER FRIDAY AT 18Z DOWN TO 45F AT BROWNSVILLE...WHILE THE GFS SHOWS A GRADUAL DECREASE DOWN TO 55F BY MONDAY MORNING. UPDATED THE GRIDS TO KEEP A 50...50 BLEND OF THE GFS AND ECMWF POPS TO ACCOUNT FOR THIS MODEL UNCERTAINTY. NO TEMPERATURE CHANGES WERE DONE AT THIS TIME. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 64 72 63 79 / 20 10 20 10 BROWNSVILLE 61 73 59 81 / 20 10 10 10 HARLINGEN 59 72 57 82 / 10 10 10 10 MCALLEN 61 73 57 82 / 10 10 10 10 RIO GRANDE CITY 59 71 57 80 / 20 10 10 20 SOUTH PADRE ISLAND 64 73 63 78 / 30 10 10 20 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT: HTTP://WWW.WEATHER.GOV/BROWNSVILLE 53/57 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 1255 AM EST WED NOV 26 2008 .SYNOPSIS... LOW PRESSURE OVER NORTHERN NEW YORK WILL SLOWLY DRIFT NORTHWARD INTO SOUTHERN QUEBEC THROUGH THURSDAY NIGHT. THIS WILL RESULT IN SEASONAL TEMPERATURES...WITH MAINLY SCATTERED SNOW SHOWERS ESPECIALLY ACROSS THE HIGHER TERRAIN NORTH AND WEST OF ALBANY. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... VERTICALLY STACKED LOW SITUATED OVER NORTHERN NY CONTINUES TO SLOWLY LIFT NORTHWARD OVERNIGHT. RADAR RETURNS ALONG THE NY-STATE THRUWAY CONTINUE TO REVEAL SOME ENHANCEMENTS. RUC13 SEEMS TO BE CAPTURING THE WEAK DEFORMATION AXIS AROUND 800MB WITH STEEP LAPSE RATES BETWEEN 800-500MB. THIS POCKET OF STEEP LAPSE RATES IS EXPECTED TO OVERSPREAD MOST OF THE CWA /EXCEPTION WOULD BE THE MID HUDSON VALLEY AND MOST OF NW CT/ AND WILL INTRODUCE LOW POPS TO ACCOUNT FOR SOME SNOW SHOWERS. WITHIN THE BETTER CONCENTRATION OF SNOW SHOWERS ALONG THE THRUWAY...BOUNDARY LAYER FLOW WILL CONTINUE TO SHIFT NORTHWARD AND THE BAND OF SNOW WILL LIFT INTO NORTHERN HERKIMER COUNTY AND THE DACKS AROUND MIDNIGHT. WILL INCLUDE 1-3 INCHES OF SNOW AT THIS TIME AS LAKE CONTRIBUTION WILL INCREASE OVERNIGHT AS DELTA T/S INCREASE OVER LAKE ONTARIO. PREVIOUS AFTERNOON DISCUSSION... LOW PRESSURE AT THE SURFACE IS IN THE PROCESS OF CONSOLIDATING ACROSS NORTHERN NY STATE...AND WILL BECOME VERTICALLY STACKED AS IT LIFTS NORTHWESTWARD INTO EXTREME SOUTHEAST ONTARIO JUST NORTH OF LAKE ONTARIO. WITH THE COLD CORE UPPER LEVEL CUT-OFF LOW DRIFTING NORTHWARD ACROSS NORTHERN PA AND CENTRAL NY...LIGHT RAIN HAS BEEN CHANGING TO SNOW WEST OF ALBANY...WITH MODERATE SNOW FALLING ACROSS THE SOUTHERN ADIRONDACKS AT THIS HOUR. PRECIP SHIELD IS RAPIDLY PROGRESSING NORTHWARD...SO WILL EXPIRE WINTER STORM WARNINGS FOR THE WESTERN/SOUTHERN ADIRONDACKS AND EASTERN CATSKILLS AS WIDESPREAD ACCUMULATING SNOW IS ENDING. STEADY PRECIP SHOULD TAPER OFF FROM SOUTH TO NORTH AS THE LOW AND ASSOC FORCING MOVE OUT OF THE AREA. WILL STILL HAVE TO LINGER LIKELY POPS ACROSS PORTIONS OF THE MOHAWK VALLEY AND WESTERN ADIRONDACKS AS A WEAK DEFORMATION ZONE ASSOC WITH THE UPPER LOW PIVOTS THROUGH. ADDITIONAL SNOW ACCUMULATIONS WILL ONLY BE AROUND AN INCH. OTHERWISE TEMPS WILL GET BACK DOWN TO BELOW FREEZING TOWARDS MORNING WITH COLD AIR ADVECTING INTO THE REGION. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... FAIRLY STAGNANT PATTERN SHAPING UP FROM WED THROUGH THUR NIGHT ACROSS THE AREA...AS THE AFOREMENTIONED VERTICALLY STACKED LOW BASICALLY SITS AND SPINS ACROSS EXTREME SOUTHEAST ONTARIO INTO SOUTHERN QUEBEC...WITH A WSW CYCLONIC FLOW REGIME SETTING UP ACROSS OUR REGION. THIS WILL RESULT IN UPSLOPE/LAKE ENHANCED SNOW SHOWERS NORTH AND WEST OF ALBANY...WITH ISOLATED TO SCATTERED RAIN/SNOW SHOWERS FARTHER SOUTH AND EAST. AT THIS TIME IT APPEARS ORGANIZED LAKE EFFECT BANDS WILL NOT AFFECT OUR FORECAST AREA...WITH AVERAGE MIXED LAYER FLOW TRAJECTORY OF 230-240 DEGREES WHICH WOULD PLACE ORGANIZED BANDS NORTH AND WEST FROM THE TUG HILL INTO THE ST LAWRENCE RIVER VALLEY. THERE MAY BE SOME VEERING OF THE WINDS AS THE LOW HEADS FARTHER NORTH BY THUR INTO THUR NIGHT...WHICH MAY ALLOW FOR A BETTER CHANCE OF LAKE BANDS TO DRIFT INTO NORTHERN HERKIMER/HAMILTON COUNTIES. FOR NOW WILL MENTION LIKELY POPS IN THESE FAVORED AREAS THROUGH THUR NIGHT...WITH LIGHT ACCUMULATIONS EACH PERIOD SO NO HEADLINES WILL BE ISSUED FOR NOW. TEMPS WILL BE FAIRLY UNIFORM BOTH WED AND THUR...WITH LOWER TO MID 30S IN THE HIGHER ELEVATIONS AND UPPER 30S TO LOWER 40S IN THE VALLEYS. && .LONG TERM /FRIDAY THROUGH TUESDAY/... THE EXTENDED PERIOD BEGINS WITH A PROGRESSIVE UPPER LEVEL TROUGH MOVING ACROSS THE NORTHEAST FOR FRIDAY. BOTH THE LATEST 12Z OPERATIONAL RUNS OF THE ECMWF AND GFS...AS WELL AS ALL OF THE 12Z MREF MEMBERS...AGREE THAT THIS NORTHERN STREAM ENERGY WILL QUICKLY MOVE THROUGH THE REGION WITH LITTLE FANFARE. WHILE SOME EARLIER RUNS SHOWED THIS CLIPPER SYSTEM PHASING WITH A SOUTHERN STREAM SYSTEM FOR SATURDAY...IT APPEARS THAT THIS CLIPPER WILL BE MOVING FAST ENOUGH THAT THE TIMING WON/T CLICK QUITE RIGHT FOR A BIG STORM TO DEVELOP. HENCE...IT APPEARS THAT WE/LL ONLY BE DEALING WITH SOME RAIN OR SNOW SHOWERS FOR DURING THE DAY WITH THE SATURDAY. WHILE IT WILL BE COOLER THAN NORMAL...IT SHOULD BE JUST WARM ENOUGH AT THE BOUNDARY LAYER IN THE VALLEYS FOR RAIN SHOWERS DURING THE DAY...ALTHOUGH HIGHER ELEVATIONS MAY SEE SOME SNOW SHOWERS. HOWEVER...WITH THE PRECIP COMING MAINLY DURING THE DAY...AND BEING QUITE LIGHT IN BOTH QPF AND INTENSITY...WOULD NOT EXPECT MUCH ACCUMULATION. THE NEXT FEATURE TO KEEP AN EYE ON WILL BE FOR EARLY NEXT WEEK. BOTH THE LATEST 12Z ECMWF/GFS AND MANY OF THE MREF MEMBERS DO HINT THAT A SOUTHERN STREAM STORM MAY DEVELOP AND RIDE UP THE EASTERN SEABOARD SOMETIME LATE SUN INTO MON. THE ECMWF PREFERS A MORE INLAND TRACK...WHILE THE GFS KEEPS THE LOW OFFSHORE. DESPITE THE ECMWF/S INLAND TRACK...IT KEEPS TEMPERATURES QUITE COLD...DESPITE A STRONG 987 MB LOW. WOULD THINK THE ECMWF IS A LITTLE TOO COLD WITH ITS 850 MB TEMPS /AROUND -6 C AT KALB AROUND 12Z MONDAY/ IF SUCH A STRONG STORM WOULD TAKE PLACE AND TRACK ACCORDING TO THE CURRENT MODEL/S PROJECTION. INTERESTINGLY ENOUGH...MANY OF THE 12Z MREF PLUMES SHOW P-TYPE MAINLY AS RAIN FOR KALB...AS THE ENSEMBLE MEMBERS HAVE A VARIETY OF TRACKS AND TIMING FOR THIS SYSTEM. OBVIOUSLY...A LOT OF UNCERTAINTY...SO WILL PLAY THE TYPICAL LONG RANGE FORECAST OF LOW CHC POPS AND CALLING FOR RAIN/SNOW BASED ON ELEVATION AND DIURNAL TRENDS. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... WIDESPREAD LOW CLOUDS COVERED MUCH OF THE GREAT LAKES AREA EXTENDING FROM SOUTHERN HUDSONS BAY DOWN THROUGH MICHIGAN AND OHIO AND EAST ACROSS ALL BUT THE SOUTHEASTERN CORNER OF NEW YORK. THERE WERE WIDESPREAD REGIONS OF IFR FLIGHT CONDITIONS NORTH AND WEST OF ALBANY. ALBANY AND ROME HAD MVFR VISIBILITY WHILE THE HUDSON VALLEY SOUTH OF ALBANY WAS VFR AND MOSTLY CLEAR...AS WERE MOST OF THE BERKSHIRES SOUTH OF THE MASS PIKE AND NORTHWESTERN CONNECTICUT. SOME OF THE LOW CLOUDS WEST OF THE CATSKILLS WILL LIKELY OVERSPREAD MUCH OF THE MID HUDSON REGION BUT CEILINGS IN THE HUDSON VALLEY SHOULD REMAIN ABOVE VFR MINIMUMS. HOWEVER OVER THE HIGHER TERRAIN OF THE SOUTHERN BERKSHIRES AND THE LITCHFIELD HILLS CEILINGS WILL PROBABLY DETERIORATE TO MVFR. WHILE THE CEILING AT GLENS FALLS WAS VFR FOG HAS LOWERED THE VISIBLITY TO BETWEEN 1/2 AND 2 MILES...AND IT IS LIKELY TO REMAIN IFR...AT LEAST PART OF THE TIME...UNTIL AFTER DAYBREAK. STRATOCU WILL LIKELY PERSIST MUCH OF TODAY WITH CEILINGS CLOSE TO VFR MINIMUMS TO THE NORTH AND LIKELY BECOMING MVFR LATE IN THE AFTERNOON...WITH SOMEWHAT MORE FAVORABLE WEATHER FARTHER SOUTH. WINDS WILL MOSTLY BE LIGHT FROM THE SOUTH. OUTLOOK... THU-FRI...VFR/MVFR. CHC -SHRA/-SHSN...MAINLY IN THE NORTH. SAT-SUN AM...VFR. NO SIG WX. SUN PM...VFR/MVFR. CHC -RA/-SN. && .HYDROLOGY... A WINTER STORM BROUGHT SIGNIFICANT PRECIPITATION TO THE REGION ON MONDAY NIGHT AND TUESDAY. PRECIPITATION TOTALS WERE HIGHEST IN OUR EASTERN NEW YORK AND WESTERN NEW ENGLAND COUNTIES WHERE 2.0 INCHES OF LIQUID EQUIVALENT FELL AT GRAFTON VERMONT...1.83 INCHES FELL AT CONKLINGVILLE DAM IN SARATOGA COUNTY...1.64 INCHES FELL AT TABORTON IN RENSSELAER COUNTY...1.26 INCHES FELL AT SAVOY MASSACHUSETTS...1.15 INCHES FELL AT NEW HARTFORD IN LITCHFIELD COUNTY CONNECTICUT...AND 1.10 INCHES FELL AT THE ALBANY AIRPORT. THE PRECIPITATION CAME MOSTLY AS RAIN FROM THE MOHAWK VALLEY SOUTH AT LOWER ELEVATIONS WITH SOME SIGNIFICANT SNOWFALL OVER THE HIGHER ELEVATIONS OF THE ADIRONDACKS...GREEN MOUNTAINS...AND CATSKILLS. WITHIN-BANKS RISES OF 6 INCHES TO OVER 2 FEET OCCURRED ON THE RIVERS WITH THE HOOSIC RIVER COMING UP TWO AND A HALF FEET AT EAGLE BRIDGE TUESDAY AFTERNOON. RIVERS SHOULD REMAIN WELL BELOW FLOOD STAGE AND THE FLOOD WATCH THAT WAS IN EFFECT FROM THE HUDSON RIVER VALLEY EASTWARD WAS CANCELLED TUESDAY AFTERNOON AFTER THE THREAT OF FLOODING SUBSIDED. GENERALLY DRY CONDITIONS...WITH A FEW SNOW/RAIN SHOWERS ARE EXPECTED THROUGH SUNDAY. RIVERS ARE EXPECTED TO CREST TODAY OR TOMORROW...AND SLOWLY RECEDE THROUGH THE THANKSGIVING WEEKEND. ANOTHER LARGE STORM SYSTEM MAY IMPACT THE REGION SUNDAY NIGHT AND MONDAY. SIGNIFICANT PRECIPITATION IS EXPECTED WITH THAT STORM...BUT THERE IS STILL SOME QUESTION AS TO HOW MUCH WILL COME IN WHAT FORM. SHOULD MOST OR ALL OF IT COME AS RAIN...IT COULD CAUSE SOME FLOODING PROBLEMS EARLY NEXT WEEK. FOR DETAILS ON THE RIVERS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...JPV/RCK NEAR TERM...BGM/RCK SHORT TERM...JPV LONG TERM...FRUGIS AVIATION...RCK HYDROLOGY...SND/RCK FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT WWW.WEATHER.GOV/ALBANY ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 430 AM EST WED NOV 26 2008 .SYNOPSIS... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE TO THE LEE OF ROCKIES WITH DOWNSTREAM TROF FROM HUDSON BAY INTO THE NE CONUS WHICH FEATURES A MID/UPPER LOW OVER NEW YORK STATE. FLOW HAS SPLIT INTO THE W COAST WITH A TROF APPROACHING CA AND A MAIN STREAM SHORTWAVE TROF MOVING ONSHORE IN THE PACIFIC NW/WRN CANADA WHERE 12HR 500MB HEIGHT FALLS WERE AROUND 90M. IT IS THIS NRN SHORTWAVE THAT WILL AFFECT THE WEATHER HERE THANKSGIVING DAY/NIGHT AS IT DROPS SE INTO THE MEAN ERN TROF. CLOSER TO HOME...AIRMASS IS NOT REALLY COLD ENOUGH FOR LES IN THE ABSENCE OF SYNOPTIC FORCING (THERE ARE ONLY A FEW HINTS OF FLURRIES OVER ERN LAKE SUPERIOR ON KMQT AND MONTREAL RIVER RADARS). 00Z SOUNDINGS SHOWED 850MB TEMPS RANGING ONLY FROM -2/-5C AT KINL/CWPL RESPECTIVELY TO -8C AT KGRB/KAPX. LOW INVERSION AROUND 920MB/2.6KFT MSL AT KINL/CWPL IS ANOTHER STRONG INHIBITOR FOR LES DEVELOPMENT. END RESULT IS A STRATUS/STRATOCU DECK...MAINLY OFF CNTRL/ERN LAKE SUPERIOR...AS AIRMASS MOVING OVER THE W LAKE PER 00Z KINL SOUNDING IS DRIER. && .DISCUSSION... QUIET DAY EXPECTED ACROSS THE FCST AREA TODAY. UPPER LOW OVER NEW YORK IS PROGGED TO DRIFT NW TODAY...BUT STILL REMAIN FAR ENOUGH TO THE E THAT -SN ON THE NW AND W FRINGE OF SYSTEM WILL REMAIN E OF THE FCST AREA. WITH LITTLE CHANGE IN 850MB TEMPS OR TEMPS NEAR THE INVERSION BASE (WARMING IF ANYTHING)...LES WILL NOT BE AN ISSUE TODAY. HOWEVER...OVER THE NE FCST AREA...THERE MAY BE A FEW FLURRIES OR SPOTTY VERY LIGHT -DZ (-FZDZ IN THE MORNING) AS MOIST LAYER WARMS ABOVE -10C...BUT POTENTIAL IS SO LIMITED WILL NOT MENTION. PLENTY OF STRATOCU SHOULD REMAIN TRAPPED UNDER INVERSION...MAINLY FROM AROUND THE KEWEENAW TO THE E HALF OF UPPER MI UNDER PERSISTENT NWRLY FLOW. WITH DRIER AIR FLOWING ACROSS WRN LAKE SUPERIOR...EXPECT SOME SUN OVER THE FAR W AND SW. EVEN OVER THE W WHERE SOME SUN WILL OCCUR...LOW MIXING HEIGHTS WILL KEEP TEMPS IN CHECK. IN GENERAL... EXPECT HIGHS IN THE 30S ACROSS THE BOARD. TONIGHT...UPPER LOW WILL REMAIN NEARLY STATIONARY TO THE E OF GEORGIAN BAY ALONG ONTARIO/QUEBEC BORDER AND ANY DEEP LAYER FORCING AROUND THE W SIDE OF SYSTEM WILL STILL REMAIN E OF THE FCST AREA. LOW-LEVEL TEMP STRUCTURE CHANGES LITTLE THOUGH THE NAM HINTS THAT THE MOISTURE DEPTH MAY IMPROVE A BIT OVER THE FAR E AS MOISTURE ADVECTS WWD. THIS WOULD MINIMIZE POTENTIAL OF ANY -DZ/-FZDZ AS MOISTURE WILL EXTEND TO AT LEAST -10C. IN LIGHT OF THE NAM OUTPUT...WILL CARRY A MENTION OF SOME FLURRIES TONIGHT OVER THE ERN FCST AREA. EXPECT DRY WEATHER TO CONTINUE ELSEWHERE. BEFORE HIGH/MID CLOUDS BEGIN TO INCREASE FROM THE NW...CLEAR/PARTLY CLOUDY SKIES SHOULD ALLOW TEMPS TO DROP INTO THE TEENS OVER THE W TONIGHT. ON THANKGIVING DAY...ATTENTION WILL TURN TO SHORTWAVE CURRENTLY OVER BRITISH COLUMBIA/WA. IT WILL REACH WI/UPPER MI BY EVENING. THERE ARE SLIGHT DIFFERENCES IN THE TRACK OF SHORTWAVE (GFS AT SRN END OF GUIDANCE)...BUT MAJORITY OF GUIDANCE POINTS TO THE MAIN STRIPE OF SNOW/DEEP LAYER FORCING STREAKING ACROSS THE FCST AREA THU AFTN/EVENING. IT REALLY WON`T BE A SITUATION FOR ISENTROPIC ASCENT AIDED PCPN DUE TO LACK OF WAA. SO...THAT WILL BE A MISSING FACTOR TO BOOST SNOW ACCUMULATIONS. 850MB TEMPS OF -6 TO -8C ACROSS LAKE SUPERIOR WILL BE SUFFICIENT FOR A PERIOD OF SOME LAKE ENHANCEMENT UNDER W WINDS SHIFTING NWRLY. WITH RESPECTABLE DEEP LAYER FORCING... EXPECT A QUICK SHOT OF -SN WITH ACCUMULATIONS GENERALLY AROUND 1 INCH OVER THE FCST AREA. LAKE ENHANCEMENT SHOULD BOOST TOTALS A LITTLE...TO 2 MAYBE 3 INCHES OVER THE NW FCST AREA. LES WILL THEN DEVELOP IN THE WAKE OF THE SHORTWAVE THU NIGHT THOUGH 850MB TEMPS AREN`T ESPECIALLY LOW...ONLY DROPPING TO -10C. GFS SHOWS A MORE DRAMATIC LOSS OF DEEP MOISTURE OVER THE W WITH SUBSIDENCE/LOWERING INVERSION TO 4-5KFT THU NIGHT. WHILE NAM MAINTAINS A MUCH DEEPER MOISTURE PROFILE...DOWNWARD MOTION IS DOMINATING THE DENDRITIC SNOW GROWTH TEMP ZONE (DGZ). TO THE E...THE GFS MAINTAINS A DEEP MOISTURE PROFILE THRU THE NIGHT INTO FRI MORNING...BUT UPWARD MOTION IS CONFINED BELOW THE DGZ. WHILE THE GFS IS GENERALLY FAVORED PER HPC DISCUSSION...EVEN IF THE NAM IS CORRECT...ITS GUIDANCE DOESN`T FAVOR SIGNIFICANT SNOW ACCUMULATIONS IN THE LES REGIME BEHIND THE SHORTWAVE THU NIGHT INTO FRI AS MESOSCALE FORCED UPWARD MOTION REMAINS BELOW THE DGZ. THUS...OVERALL...IT DOESN`T LOOK LIKE LES WILL BE A BIG DEAL. PROBABLY LOOKING AT ACCUMULATIONS IN THE 1-2 TO MAYBE 3 INCH RANGE OVERNIGHT THU THRU FRI MORNING IN THE NW FLOW FAVORED SNOWBELTS. ANOTHER INCH POSSIBLE FRI AFTN...MAINLY E...AS DRYING PROGRESSES E INTO THE UPPER LAKES. BEYOND FRI...PATTERN REMAINS PERSISTENT WITH FCST AREA UNDER THE INFLUENCE OF ERN NAMERICA TROF. A SERIES OF SHORTWAVES WILL BE SLIDING SE INTO THE ERN TROF OVER THE WEEKEND THRU AT LEAST THE MIDDLE OF NEXT WEEK. AIRMASS WILL GENERALLY BE COLD ENOUGH TO SUPPORT LES WHICH WILL BE ENHANCED PERIODICALLY BY PASSING SHORTWAVES. HOWEVER...AT THIS TIME...IT DOES NOT APPEAR THAT ANY SIGNIFICANT SNOW WILL OCCUR. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... OVERALL EXPECT MVFR CIGS TO PREVAIL AT KCMX/KSAW THRU THE THE FCST PERIOD AS LOW-LEVEL MOISTURE REMAINS TRAPPED BELOW A PERSISTENT STRONG INVERSION. CLOUDS COULD BRIEFLY SCATTER OUT AT KCMX...BUT NOT ENOUGH CONFIDENCE IS PRESENT TO INCLUDE ANY TEMPO GROUPS FOR SCT. AT KSAW...MVFR CIGS ARE JUST TO THE EAST...WHICH WILL FILTER BACK IN BTWN 12Z-15Z AS A SFC TROUGH DROPS SOUTH ACROSS LAKE SUPERIOR. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EASTERN HALF OF LAKE SUPERIOR WILL REMAIN UNDER THE INFLUENCE OF GRADIENT ASSOCIATED WITH SFC LOW NEAR LAKE ONTARIO. EXPECT NORTHERLY WINDS IN THE 15 TO 25 KNOT RANGE TO CONTINUE THROUGH TONIGHT... POSSIBLY INCREASING TO 30 KNOTS LATE THIS AFTERNOON AND EVENING AS THE LOW BEGINS LIFTING NORTHWARD INTO WESTERN QUEBEC. ACROSS WESTERN LAKE SUPERIOR...THE EFFECTS FROM SFC RIDGING WILL RESULT IN LIGHTER WINDS THERE. ON THU...THIS RIDGE IS EXPECTED TO DISSIPATE AS IT CROSSES LAKE SUPERIOR. LOOK FOR A LOW PRESSURE AREA TO FOLLOW IN THE WAKE OF THE RIDGE...CROSSING UPPER MICHIGAN THU AFTN. IN ITS WAKE...NORTHWEST WINDS OF 15 TO 25 KNOTS WILL DOMINATE LAKE SUPERIOR FOR LATER THU NIGHT INTO FRI. GUSTS COULD REACH 30 KNOTS ON EASTERN LAKE SUPERIOR LATE FRI. ANOTHER WEAKENING RIDGE OF HIGH PRESSURE IS EXPECTED TO CROSS LAKE SUPERIOR FRI NIGHT INTO SAT...ALLOWING WINDS TO RELAX BELOW 20 KNOTS. FOR SAT NIGHT INTO SUN...LOW PRESSURE DROPPING OUT OF THE NORTHERN PLAINS AND MOVING INTO LOWER MICHIGAN WILL CAUSE NORTH WINDS TO INCREASE TO 15 TO 25 KNOTS ON ALL OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...ROLFSON AVIATION...JLB/AJ MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 351 AM EST WED NOV 26 2008 .SYNOPSIS... SURFACE LOW PRESSURE OVER SOUTHERN ONTARIO WILL MEANDER ACROSS ONTARIO THROUGH THURSDAY. ANOTHER SURFACE LOW WILL DEVELOP OVER THE CENTRAL GREAT LAKES ON FRIDAY AND DRAG ANOTHER COLD FRONT ACROSS THE REGION ON FRIDAY. HIGH PRESSURE WILL BRIEFLY MOVE ACROSS THE AREA SATURDAY AND THEN ANOTHER WEATHER SYSTEM WILL AFFECT THE REGION SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS THE FLOW BECOMES WESTERLY THE CLOUDS WILL DECREASE OVER NORTHWEST AND NORTH CENTRAL OHIO. ELSEWHERE EXCEPT IN THE SNOW BELT COULD SEE SOME PEEKS OF SUN. MOST MODELS HAVE THE FLOW WESTERLY FOR THE AFTERNOON. THE RUC KEEPS IT 290 DEGREES. IF THE RUC IS RIGHT THIS WOULD KEEP SOME SNOW SHOWERS GOING LONGER IN THE NORTHERN PARTS OF SUMMIT...PORTAGE AND TRUMBULL. AT THIS TIME WILL GO WITH THE FLOW BECOME WESTERLY ALOFT BY NOON. WILL CONTINUE THE ADVISORY MAINLY FOR THE NORTHERN PORTIONS OF SUMMIT AND PORTAGE COUNTIES. WILL MONITOR CONDITIONS AND MAY BE ABLE TO DROP SUMMIT COUNTY BY DAYBREAK. WILL NOT CHANGE WINTER WEATHER ADVISORY TO LAKE EFFECT...THAT WOULD BE CONFUSING...BUT EMPHASIZE THE NORTH. FOR CUYAHOGA ON THE EDGE WHETHER THE ADVISORY NEEDS TO BE EXTENDED INTO THE EVENING. THE MODELS ARE TRYING TO INDICATE A SHORT WAVE MOVING THROUGH THIS AFTERNOON...HOWEVER...WITH THE LAKE AND 850 MB TEMPERATURE BARELY 13C AND SOME DRYING NOT CONFIDENT ENOUGH EXTEND THE ADVISORY. ELSEWHERE IN THE SNOW BELT EXCEPT FOR NORTHWEST PA THE MODELS ONLY TRY TO GIVE A FEW INCHES OF SNOW. NOT CONVINCED THAT IS RIGHT. LOCATIONS RIGHT ALONG THE LAKE HAVE BEEN RAIN. THEY SHOULD BECOME SNOW BY 12Z. WILL NOT MENTION THAT IN THE FORECAST AT THE MOMENT. WENT CLOSE TO MAV MOS FOR HIGHS TODAY...THE SUN WILL HELP TEMPERATURES MODERATE. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... IN THE WESTERLY FLOW...ON THE EDGE ABOUT HOW LONG THE SIGNIFICANT SNOWFALL WILL CONTINUE WITH THE 850 MB WARMING AND SOME DRYING ALOFT...AND THE LAKE AND 850 MB TEMPERATURE JUST NEAR 13C. NO SIGNIFICANT SHORT WAVES OVERNIGHT BUT CYCLONIC FLOW. THE LOCAL MESOSCALE MODELS ARE NOT SHOWING WARNING AMOUNTS FOR LATE TONIGHT. AT THIS TIME WILL NOT EXTEND THE WARNINGS. THE DAYSHIFT WILL HAVE TO MONITOR THIS. ELSEWHERE PARTLY CLOUDY TONIGHT. LIGHT WINDS. THE AREAS WITH SNOWCOVER WILL BE FAIRLY COOL. WENT A LITTLE COLDER THAN GUIDANCE. FOR THURSDAY SOME LAKE EFFECT SNOW CONTINUING FROM ASHTABULA COUNTY EAST INTO NW PA...AMOUNTS SHOULD BE LIGHT. AT THIS TIME WILL KEEP IT A 60 POP WITH ADEQUATE AMOUNTS OF MOISTURE. ELSEWHERE PARTLY CLOUDY. THE MORNING WILL START WITH SOME SUN AND THEN INCREASING CIRRUS...PARTLY CLOUDY SHOULD WORK. BECAUSE OF THE CLOUDS THAT WILL KEEP THE HIGHS FROM GETTING TOO WARM. WENT WITH THE WARMER MOS NUMBERS. FOR THURSDAY NIGHT...THE MODELS ESPECIALLY THE NAM IS KIND OF DRY I.E. NOT MUCH QPF. WITH THE FRONT MOVING IN AND SOME QUESTION WHEN THEY WILL SWITCH AND COME OFF THE LAKE WILL CONTINUE WITH THE CHANCE POPS MAINLY EAST OF CLE. ON FRIDAY THE QPF FROM THE NAM IF VERY ISOLATED WHILE THE GFS HAS SOME QPF EVERYWHERE...THE HIGHEST CHANCE WILL BE THE SNOWBELT EVEN THOUGH THE LAKE AND 850 MB TEMPERATURE DIFFERENCE WILL BE NEAR 12C. WILL PROBABLY KEEP JUST 20 POPS NORTHWEST OHIO AS CONFIDENCE IS NOT STRONG ENOUGH. THE GEM IS DRY AND THE ECMWF IS LIKE THE GFS WITH SOME QPF. THE SLOWNESS OF THE NAM AND GEM MOVING IN THE MOISTURE IS THE REASON WHY IT IS SO DRY. FOR FRIDAY NIGHT WILL WILL CONTINUE THE FORECAST AS IS. AGAIN THE NAM AND GEM ARE DRY BUT THE OTHER MODELS HAVE SOME QPF. WITH THE FLOW SOMEWHAT NORTHWEST AND SOME MOISTURE AND THE LAKE AND 850 MB TEMPERATURE DIFFERENCE NEAR 13 AND 14C THAT SHOULD BE GOOD ENOUGH FOR SOME SNOW SHOWERS AND WITH SOME CYCLONICNESS ALOFT THAT WILL HELP. MODELS DEFINITELY DON`T AGREE. THIS DISAGREEMENT CONTINUES INTO SATURDAY. WILL KEEP THE WEST DRY AND LIMIT THE CHANCE IN THE EAST TO MAINLY THE MORNING. FOR SATURDAY NIGHT THE GFS SEEMS TO INCREASE THE MOISTURE WAY TO QUICKLY WITH THE NEXT SYSTEM. WILL KEEP IT DRY. FOR THURSDAY NIGHT THROUGH SATURDAY NIGHT WENT WITH GRIDDED MOS FOR THE TEMPERATURES. THEY LOOK REASONABLE. && .LONG TERM /SUNDAY THROUGH TUESDAY/... FEW CHANGES TO LONG TERM PERIOD. MODELS NOT IN VERY GOOD AGREEMENT WITH SMALL FEATURES TODAY SO A LOT OF UNCERTAINTY IN FORECAST. THUS WILL HOLD OFF ON MAKING ANY SIGNIFICANT CHANGES. PERIOD WILL START WITH LINGERING PRECIP CHANCES FRIDAY NIGHT WITH COLD FLOW ACROSS LAKE ERIE. NEXT LOW IS EXPECTED TO MOVE ACROSS THE CENTRAL LAKES ON SUNDAY AND DRAG A FRONT ACROSS THE AREA. GFS AND ECMWF HAVE DIFFERING SOLUTIONS FOR THIS SYSTEM SO FOR NOW WILL JUST GO WITH CHANCE WORDING ALL AREAS. FINE TUNING WILL BE NEEDED AS MODELS COME INTO BETTER AGREEMENT. THERE WILL BE LINGERING LAKE EFFECT BEHIND THIS FRONT ON MONDAY AND TUESDAY. HAVE LOWERED TEMPS FROM GUIDANCE...ESPECIALLY ACROSS NE OH AND NW PA WHERE A SIGNIFICANT SNOW PACK WILL REMAIN ON THE GROUND. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... SURFACE LOW HAS NOW TRANSLATED TO NORTHERN NEW YORK STATE IN CLOSE PROXIMITY TO THE UPPER SYSTEM. SYSTEM WILL CONTINUE NORTH INTO SOUTHERN QUEBEC AND SOUTHEASTERN ONTARIO FOR WEDNESDAY. MOIST NORTHWEST FLOW BEHIND THE SYSTEM CONTINUES ALOFT OVER THE AREA HOWEVER MUCH OF THE SYNOPTIC FORCING HAS DISSIPATED. WIDESPREAD SNOW ACROSS THE AREA EARLIER IN THE EVENING HAS DIMINISHED INTO TWO WEAK BANDS. ONE BAND IS AFFECTING KYNG WHILE THE OTHER EXTENDS THROUGH LORAIN COUNTY INTO MEDINA COUNTY AND POINTS SSE. AS WINDS BACK THROUGH THE FIRST HALF OF THE NIGHT EXPECT THESE BANDS TO BECOME DISRUPTED AND LIKELY DISSIPATE AS THEY DRIFT EAST. LAKE-850MB TEMPS SHOWING ONLY CONDITIONAL INSTABILITY SO MAY ONLY PRODUCE LIMITED LAKE EFFECT SNOW FOR ERIE LATE TONIGHT AND WEDNESDAY AS LONG FETCH WEST WINDS TAKE ANY LAKE EFFECT SNOW INTO THE ERIE AREA. IN GENERAL...THROUGH THE NIGHT EXPECT CEILINGS TO SLOWLY LIFT FROM THE WEST AS SLIGHTLY DRIER AIR MOVES IN FROM THE WEST. ACROSS THE WEST EXPECT VFR CONDITIONS WEDNESDAY. IN THE CENTRAL AND EAST MORNING MVFR WILL LIFT TO VFR THROUGH THE DAY. OUTLOOK...WIDESPREAD VFR EXPECTED THURSDAY AS HIGH PRESSURE MOVES ACROSS THE LOWER LAKES. MORE SNOW IS EXPECTED FRIDAY AS ANOTHER COLD FRONT MOVES THROUGH. SATURDAY LOOKS DRY AGAIN AND LIKELY VFR ACROSS THE AREA. SUNDAY EXPECT MVFR/IFR TO MOVE BACK IN AS ANOTHER SYSTEM DRAGS DEEP MOISTURE INTO THE LOWER LAKES. && .MARINE... SMALL CRAFT WILL CONTINUE THROUGH WEDNESDAY NIGHT. LOW OVER NEW ENGLAND WILL DRIFT INTO SOUTHERN ONTARIO THURSDAY THUS KEEPING A WEST-SOUTHWESTERLY FLOW OVER THE LAKE. SMALL CRAFT WILL BE NEEDED AGAIN FRIDAY AS ANOTHER COLD FRONT MOVES ACROSS THE LAKE. ALSO EXPECT MORE LAKE EFFECT SNOW AS 850 TEMPS DROP TO -9C. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR OHZ012>014-089. WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR OHZ011- 021>023. PA...LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR PAZ001>003. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST THURSDAY FOR LEZ142>149. && $$ SYNOPSIS...KIELTYKA NEAR TERM...KIELTYKA SHORT TERM...KIELTYKA LONG TERM...DJB/KUBINA AVIATION...TK MARINE...DJB oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1040 AM EST WED NOV 26 2008 .SYNOPSIS... SLOW MOVING LOW PRESSURE OVER SOUTHEAST CANADA WILL PROVIDE MAINLY DRY AND COOL WEATHER ACROSS SOUTHERN NEW ENGLAND INTO THANKSGIVING DAY. A COLD FRONT WILL BRING A CHANCE OF RAIN OR SNOW SHOWERS TO THE REGION FRI. MAINLY DRY AND COOL WEATHER RETURNS SAT. LOW PRES APPROACHING SOUTHERN NEW ENGLAND LATER SUNDAY OR EARLY NEXT WEEK PRODUCES THE NEXT CHANCE OF SIGNIFICANT RAIN OR SNOW. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MXD SNOW SLEET AND RAIN OCEAN EFFECT PRECIPITATION INVADING CAPE COD WILL TRANSITION TO SCT RAIN SHOWERS MIDDAY AND THEN END AS FLOW TURNS MORE WLY THIS AFTERNOON. OTRW THE TYPICAL INSTABILITY INTERIOR HIGH TERRAIN SPRINKLES/FLURRIES THIS AFTERNOON AS ALREADY GRIDDED FROM PREV SHIFTS. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... ANY RAIN OR SNOW SHOWERS WILL COME TO AN END AROUND SUNSET AS DIURNAL HEATING DIMINISHES AND UPPER LEVEL TROF EXITS NORTHEAST. THEREFORE EXPECTING DRY WEATHER TONIGHT ALONG WITH DECREASING CLOUDS. SEASONABLY COLD TEMPS ARE ALSO EXPECTED. SREF AND GFS CONT TO ADVERTISE REDEVELOPMENT OF OCEAN EFFECT SHOWERS TONIGHT AT NANTUCKET AND MVY AND THIS COULD BE A CHANGE WE MAKE IN THE 4 PM FCST. MORE OF THE SAME THANKSGIVING DAY AS MID/UPPER LOW CONTINUES TO SPIN OVER SOUTHERN PORTIONS OF ONTARIO AND QUEBEC...WITH WEAK SHORT WAVES PINWHEELING ACROSS SOUTHERN NEW ENGLAND. SO ANOTHER ROUND OF CLOUDS ARE EXPECTED...ESPECIALLY DURING MAX HEATING. FOR NOW WE WILL KEEP FORECAST DRY AS MODEL TIME SECTIONS SUGGEST COLUMN DRIER THU THAN TODAY. && .LONG TERM /FRIDAY THROUGH TUESDAY/... FRIDAY...A COLD FRONT APPROACHES FROM THE GREAT LAKES. A DEVELOPING WARM AIR ADVECTION PATTERN WILL BRING INCREASING CLOUDS TO THE REGION. MOISTURE CONVERGENCE IS FAIRLY WEAK EXCEPT IN THE VICINITY OF THE COLD FRONT LATE IN THE DAY...WITH SOUTHWEST WINDS ALOFT AND SOUTH WINDS TRANSPORTING MOISTURE AT THE SURFACE. THERE APPEARS TO BE A BRIEF GULF MOISTURE CONNECTION WHICH SHOULD TEMPORARILY HELP INCREASE CHANCES FOR PRECIPITATION. A SHORT WAVE WILL ACCOMPANY THE FRONT...BUT IT APPEARS TO DAMPEN WITH TIME. TEMPERATURES ACROSS THE HIGHER TERRAIN NORTHWESTERN MASSACHUSETTS AND SOUTHWESTERN NEW HAMPSHIRE SHOULD BE COLD ENOUGH TO SUPPORT SOME WET SNOW. OTHERWISE BOUNDARY LAYER TEMPS WILL BE TOO WARM. OVERALL HAVE INCLUDED MENTION OF CHANCE POPS AT THIS TIME. FRIDAY NIGHT...LINGERING RAIN OR SNOW SHOWERS POSSIBLE DURING THE EARLY EVENING IN THE VICINITY OF THE FRONT...OTHERWISE THE COLD FRONT IS EXPECTED TO PUSH OFFSHORE. BEST CHANCE FOR LINGERING RAIN OR SNOW SHOWERS SHOULD BE ACROSS EASTERN SECTIONS. CONTINUED CHANCE POPS AT THIS TIME DURING THE EVENING. MODEL TRENDS HAVE INDICATED A QUICKER FROPA SO HAVE SPED UP TIMING BY A FEW HOURS. SATURDAY...DRY AND SEASONABLY COOL CONDITIONS EXPECTED. SUNDAY THROUGH MONDAY...SOME DISCREPANCIES DEVELOP BETWEEN THE GFS/UKMET AND ECMWF REGARDING THE AMPLITUDE AND POSITIONING OF THE UPPER LEVEL TROUGH ACROSS THE GREAT LAKES AND OHIO VALLEY REGIONS. MODELS ARE IN DISAGREEMENT REGARDING THE UPPER LEVEL JET STRUCTURE WITH THE APPROACHING PACIFIC AND SUBTROPICAL JET MAXIMA...AND THIS RESULTS IN SOME PHASING AND TIMING ISSUES FOR SECONDARY LOW PRESSURE DEVELOPING OFF THE MID ATLANTIC COAST. THE GFS FAVORS MORE OF A DUAL JET STRUCTURE AND WEAKER SECONDARY LOW WHILE THE ECMWF DOES NOT. SO CONFIDENCE REMAINS SOMEWHAT LOW REGARDING THE TIMING OF PRECIPITATION. PRECIPITATION TYPE WILL ALSO BE AN ISSUE. GIVEN THE LACK OF A STRONG SURFACE HIGH AND COLD AIR DAMMING SIGNATURE AND FAIRLY WARM OCEAN TEMPERATURES... PRECIPITATION SHOULD BEGIN AS WET SNOW OR A MIX OF SNOW AND RAIN ALONG THE INTERIOR SUNDAY AFTERNOON...WITH RAIN ALONG THE COAST. PRECIPITATION COULD CHANGE TO RAIN OVER MUCH OF THE REGION SUNDAY NIGHT DEPENDING HOW QUICKLY THE LOW INTENSIFIES NEAR THE AREA. LINGERING SNOW AND RAIN SHOWERS WILL BE POSSIBLE MONDAY WITH WRAP AROUND MOISTURE AND THE APPROACH OF THE LOWS ASSOCIATED UPPER LEVEL LOW. AGAIN THIS SCENARIO COULD CHANGE GIVEN THE TRACK AND TIMING OF THE LOW. OVERALL HAVE INCLUDED CHANCE POPS BOTH DAYS. TUESDAY...00Z GFS DEVELOPS ANOTHER LOW OFF THE SOUTHEASTERN ATLANTIC COAST WHILE THE ECMWF REMAINS DRY AND PROGRESSIVE. HAVE LEFT JUST SLIGHT CHANCE POPS AT THIS TIME. && .AVIATION /16Z WEDNESDAY THROUGH SUNDAY/... TODAY...VFR CIGS WITH SPOTTY MVFR CIGS ORH AND ALSO IN SCT PCPN. USING RUC TSECS FOR TODAYS DEFINITION OF MODELED CIGS. HAVE BEEN LOOKING AT THESE FOR SEVERAL SHIFTS AND THESE SEEMS TO DOM A BETTER JOB DEFINING CIGS THAN THE MORE DILITED CONSTANT RH LAYERS IN GFS/NAM TSECS. TONIGHT...VFR. THURSDAY...VFR IN THE MORNING TRANSITIONING TO MVFR DURING THE AFTERNOON. OUTLOOK...FRIDAY THROUGH SUNDAY... FRIDAY...VFR...THEN MVFR LATE WITH DEVELOPING RAIN SHOWERS. SATURDAY...MVFR/IFR WITH SNOW OR RAIN SHOWERS PRIOR TO DAYBREAK. OTHERWISE IMPROVEMENT TO VFR WITH COLD FROPA AND WINDSHIFT TO WEST. SUNDAY...VFR DECREASING TO MVFR THEN AREAS IFR CONDITIONS POSSIBLY DEVELOPING LATE IN THE DAY AS LOW PRESSURE APPROACHES FROM THE SOUTH. RAIN DEVELOPS NEAR THE COAST WITH SNOW OR A MIX OF SNOW AND RAIN DEVELOPING INLAND. && .MARINE... TODAY... LEFTOVER SWELLS FROM YESTERDAY/S SE GALE. SW WINDS 10-15 KT WITH GUSTS TO 20 KT. TONIGHT... SWELLS SLOWLY SUBSIDE BUT REMAIN LARGE ACROSS THE OCEAN WATERS. SW WINDS 10-15 KT. THU... SW 10-15G20KT CONTINUES. SE SWELLS CONTINUE TO DIMINISH BUT SW WIND WAVES WILL PERSIST. OUTLOOK...THURSDAY NIGHT THROUGH SATURDAY... FRIDAY...SMALL CRAFT ADVISORIES MAY BE NECESSARY FOR A PORTION OF THE COASTAL WATERS. SW WINDS MAY GUST NEAR 25 KT ALONG THE S COAST. SEAS SHOULD BUILD TO 4 TO 6 FT ACROSS THE OPEN WATERS. SATURDAY...W WINDS GUSTING TO 20 KT BEHIND THE COLD FRONT. OTHERWISE A SMALL CRAFT ADVISORY FOR SEAS MAY BE NECESSARY WITH SEAS 4 TO 6 FT ACROSS THE OPEN WATERS. SUNDAY...WINDS SHIFTING TO ESE WITH GUSTS UP TO 20 KT AS LOW PRESSURE DEVELOPS ALONG THE MID ATLANTIC COAST. SEAS 3 TO 5 FT ACROSS THE OPEN WATERS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 7 PM EST THURSDAY FOR ANZ250-254-255. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM EST THURSDAY FOR ANZ235-237. && $$ SYNOPSIS...DRAG/NOCERA/STRAUSS NEAR TERM...DRAG SHORT TERM...DRAG/NOCERA LONG TERM...STRAUSS AVIATION...DRAG/NOCERA/STRAUSS 1040 MARINE...DRAG/NOCERA/STRAUSS ct AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1145 AM EST WED NOV 26 2008 UPDATED AVIATION DISCUSSION FOR 18Z TAF ISSUANCE .SYNOPSIS... (ISSUED AT 430 AM EST) WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE TO THE LEE OF ROCKIES WITH DOWNSTREAM TROF FROM HUDSON BAY INTO THE NE CONUS WHICH FEATURES A MID/UPPER LOW OVER NEW YORK STATE. FLOW HAS SPLIT INTO THE W COAST WITH A TROF APPROACHING CA AND A MAIN STREAM SHORTWAVE TROF MOVING ONSHORE IN THE PACIFIC NW/WRN CANADA WHERE 12HR 500MB HEIGHT FALLS WERE AROUND 90M. IT IS THIS NRN SHORTWAVE THAT WILL AFFECT THE WEATHER HERE THANKSGIVING DAY/NIGHT AS IT DROPS SE INTO THE MEAN ERN TROF. CLOSER TO HOME...AIRMASS IS NOT REALLY COLD ENOUGH FOR LES IN THE ABSENCE OF SYNOPTIC FORCING (THERE ARE ONLY A FEW HINTS OF FLURRIES OVER ERN LAKE SUPERIOR ON KMQT AND MONTREAL RIVER RADARS). 00Z SOUNDINGS SHOWED 850MB TEMPS RANGING ONLY FROM -2/-5C AT KINL/CWPL RESPECTIVELY TO -8C AT KGRB/KAPX. LOW INVERSION AROUND 920MB/2.6KFT MSL AT KINL/CWPL IS ANOTHER STRONG INHIBITOR FOR LES DEVELOPMENT. END RESULT IS A STRATUS/STRATOCU DECK...MAINLY OFF CNTRL/ERN LAKE SUPERIOR...AS AIRMASS MOVING OVER THE W LAKE PER 00Z KINL SOUNDING IS DRIER. && .DISCUSSION... (ISSUED AT 430 AM EST) QUIET DAY EXPECTED ACROSS THE FCST AREA TODAY. UPPER LOW OVER NEW YORK IS PROGGED TO DRIFT NW TODAY...BUT STILL REMAIN FAR ENOUGH TO THE E THAT -SN ON THE NW AND W FRINGE OF SYSTEM WILL REMAIN E OF THE FCST AREA. WITH LITTLE CHANGE IN 850MB TEMPS OR TEMPS NEAR THE INVERSION BASE (WARMING IF ANYTHING)...LES WILL NOT BE AN ISSUE TODAY. HOWEVER...OVER THE NE FCST AREA...THERE MAY BE A FEW FLURRIES OR SPOTTY VERY LIGHT -DZ (-FZDZ IN THE MORNING) AS MOIST LAYER WARMS ABOVE -10C...BUT POTENTIAL IS SO LIMITED WILL NOT MENTION. PLENTY OF STRATOCU SHOULD REMAIN TRAPPED UNDER INVERSION...MAINLY FROM AROUND THE KEWEENAW TO THE E HALF OF UPPER MI UNDER PERSISTENT NWRLY FLOW. WITH DRIER AIR FLOWING ACROSS WRN LAKE SUPERIOR...EXPECT SOME SUN OVER THE FAR W AND SW. EVEN OVER THE W WHERE SOME SUN WILL OCCUR...LOW MIXING HEIGHTS WILL KEEP TEMPS IN CHECK. IN GENERAL... EXPECT HIGHS IN THE 30S ACROSS THE BOARD. TONIGHT...UPPER LOW WILL REMAIN NEARLY STATIONARY TO THE E OF GEORGIAN BAY ALONG ONTARIO/QUEBEC BORDER AND ANY DEEP LAYER FORCING AROUND THE W SIDE OF SYSTEM WILL STILL REMAIN E OF THE FCST AREA. LOW-LEVEL TEMP STRUCTURE CHANGES LITTLE THOUGH THE NAM HINTS THAT THE MOISTURE DEPTH MAY IMPROVE A BIT OVER THE FAR E AS MOISTURE ADVECTS WWD. THIS WOULD MINIMIZE POTENTIAL OF ANY -DZ/-FZDZ AS MOISTURE WILL EXTEND TO AT LEAST -10C. IN LIGHT OF THE NAM OUTPUT...WILL CARRY A MENTION OF SOME FLURRIES TONIGHT OVER THE ERN FCST AREA. EXPECT DRY WEATHER TO CONTINUE ELSEWHERE. BEFORE HIGH/MID CLOUDS BEGIN TO INCREASE FROM THE NW...CLEAR/PARTLY CLOUDY SKIES SHOULD ALLOW TEMPS TO DROP INTO THE TEENS OVER THE W TONIGHT. ON THANKSGIVING DAY...ATTENTION WILL TURN TO SHORTWAVE CURRENTLY OVER BRITISH COLUMBIA/WA. IT WILL REACH WI/UPPER MI BY EVENING. THERE ARE SLIGHT DIFFERENCES IN THE TRACK OF SHORTWAVE (GFS AT SRN END OF GUIDANCE)...BUT MAJORITY OF GUIDANCE POINTS TO THE MAIN STRIPE OF SNOW/DEEP LAYER FORCING STREAKING ACROSS THE FCST AREA THU AFTN/EVENING. IT REALLY WON`T BE A SITUATION FOR ISENTROPIC ASCENT AIDED PCPN DUE TO LACK OF WAA. SO...THAT WILL BE A MISSING FACTOR TO BOOST SNOW ACCUMULATIONS. 850MB TEMPS OF -6 TO -8C ACROSS LAKE SUPERIOR WILL BE SUFFICIENT FOR A PERIOD OF SOME LAKE ENHANCEMENT UNDER W WINDS SHIFTING NWRLY. WITH RESPECTABLE DEEP LAYER FORCING... EXPECT A QUICK SHOT OF -SN WITH ACCUMULATIONS GENERALLY AROUND 1 INCH OVER THE FCST AREA. LAKE ENHANCEMENT SHOULD BOOST TOTALS A LITTLE...TO 2 MAYBE 3 INCHES OVER THE NW FCST AREA. LES WILL THEN DEVELOP IN THE WAKE OF THE SHORTWAVE THU NIGHT THOUGH 850MB TEMPS AREN`T ESPECIALLY LOW...ONLY DROPPING TO -10C. GFS SHOWS A MORE DRAMATIC LOSS OF DEEP MOISTURE OVER THE W WITH SUBSIDENCE/LOWERING INVERSION TO 4-5KFT THU NIGHT. WHILE NAM MAINTAINS A MUCH DEEPER MOISTURE PROFILE...DOWNWARD MOTION IS DOMINATING THE DENDRITIC SNOW GROWTH TEMP ZONE (DGZ). TO THE E...THE GFS MAINTAINS A DEEP MOISTURE PROFILE THRU THE NIGHT INTO FRI MORNING...BUT UPWARD MOTION IS CONFINED BELOW THE DGZ. WHILE THE GFS IS GENERALLY FAVORED PER HPC DISCUSSION...EVEN IF THE NAM IS CORRECT...ITS GUIDANCE DOESN`T FAVOR SIGNIFICANT SNOW ACCUMULATIONS IN THE LES REGIME BEHIND THE SHORTWAVE THU NIGHT INTO FRI AS MESOSCALE FORCED UPWARD MOTION REMAINS BELOW THE DGZ. THUS...OVERALL...IT DOESN`T LOOK LIKE LES WILL BE A BIG DEAL. PROBABLY LOOKING AT ACCUMULATIONS IN THE 1-2 TO MAYBE 3 INCH RANGE OVERNIGHT THU THRU FRI MORNING IN THE NW FLOW FAVORED SNOWBELTS. ANOTHER INCH POSSIBLE FRI AFTN...MAINLY E...AS DRYING PROGRESSES E INTO THE UPPER LAKES. BEYOND FRI...PATTERN REMAINS PERSISTENT WITH FCST AREA UNDER THE INFLUENCE OF ERN NAMERICA TROF. A SERIES OF SHORTWAVES WILL BE SLIDING SE INTO THE ERN TROF OVER THE WEEKEND THRU AT LEAST THE MIDDLE OF NEXT WEEK. AIRMASS WILL GENERALLY BE COLD ENOUGH TO SUPPORT LES WHICH WILL BE ENHANCED PERIODICALLY BY PASSING SHORTWAVES. HOWEVER...AT THIS TIME...IT DOES NOT APPEAR THAT ANY SIGNIFICANT SNOW WILL OCCUR. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... MVFR CIGS FROM LAKE EFFECT MOISTURE TRAPPED BELOW AN INVERSION ARE EXPECTED TO REMAIN IN PLACE THROUGH THE FORECAST PERIOD...THANKS TO COOL NW WINDS FLOWING ACROSS LK SUPERIOR. THERE IS A POSSIBILITY FOR SOME SCATTERING OF THE CLOUDS AT CMX LATE THIS AFTN AS DRIER AIR OVER THE MINNESOTA ARROWHEAD MOVES IN. SKIES MAY ALSO CLEAR FOR A TIME AT SAW TONIGHT ONCE LOW LEVEL WINDS BACK TO THE NW BRINGING IN DRIER AIR. LOW CLOUDS RETURN ON THURSDAY MORNING AHEAD OF INCOMING LOW PRESSURE SYSTEM. SNOW WITH THE SYSTEM SHOULD HOLD OFF TIL THURSDAY AFTERNOON. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EASTERN HALF OF LAKE SUPERIOR WILL REMAIN UNDER THE INFLUENCE OF GRADIENT ASSOCIATED WITH SFC LOW NEAR LAKE ONTARIO. EXPECT NORTHERLY WINDS IN THE 15 TO 25 KNOT RANGE TO CONTINUE THROUGH TONIGHT... POSSIBLY INCREASING TO 30 KNOTS LATE THIS AFTERNOON AND EVENING AS THE LOW BEGINS LIFTING NORTHWARD INTO WESTERN QUEBEC. ACROSS WESTERN LAKE SUPERIOR...THE EFFECTS FROM SFC RIDGING WILL RESULT IN LIGHTER WINDS THERE. ON THU...THIS RIDGE IS EXPECTED TO DISSIPATE AS IT CROSSES LAKE SUPERIOR. LOOK FOR A LOW PRESSURE AREA TO FOLLOW IN THE WAKE OF THE RIDGE...CROSSING UPPER MICHIGAN THU AFTN. IN ITS WAKE...NORTHWEST WINDS OF 15 TO 25 KNOTS WILL DOMINATE LAKE SUPERIOR FOR LATER THU NIGHT INTO FRI. GUSTS COULD REACH 30 KNOTS ON EASTERN LAKE SUPERIOR LATE FRI. ANOTHER WEAKENING RIDGE OF HIGH PRESSURE IS EXPECTED TO CROSS LAKE SUPERIOR FRI NIGHT INTO SAT...ALLOWING WINDS TO RELAX BELOW 20 KNOTS. FOR SAT NIGHT INTO SUN...LOW PRESSURE DROPPING OUT OF THE NORTHERN PLAINS AND MOVING INTO LOWER MICHIGAN WILL CAUSE NORTH WINDS TO INCREASE TO 15 TO 25 KNOTS ON ALL OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...ROLFSON AVIATION...JLA MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 622 AM EST WED NOV 26 2008 UPDATED AVIATION DISCUSSION FOR 12Z TAF ISSUANCE .SYNOPSIS... (ISSUED AT 430 AM EST) WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE TO THE LEE OF ROCKIES WITH DOWNSTREAM TROF FROM HUDSON BAY INTO THE NE CONUS WHICH FEATURES A MID/UPPER LOW OVER NEW YORK STATE. FLOW HAS SPLIT INTO THE W COAST WITH A TROF APPROACHING CA AND A MAIN STREAM SHORTWAVE TROF MOVING ONSHORE IN THE PACIFIC NW/WRN CANADA WHERE 12HR 500MB HEIGHT FALLS WERE AROUND 90M. IT IS THIS NRN SHORTWAVE THAT WILL AFFECT THE WEATHER HERE THANKSGIVING DAY/NIGHT AS IT DROPS SE INTO THE MEAN ERN TROF. CLOSER TO HOME...AIRMASS IS NOT REALLY COLD ENOUGH FOR LES IN THE ABSENCE OF SYNOPTIC FORCING (THERE ARE ONLY A FEW HINTS OF FLURRIES OVER ERN LAKE SUPERIOR ON KMQT AND MONTREAL RIVER RADARS). 00Z SOUNDINGS SHOWED 850MB TEMPS RANGING ONLY FROM -2/-5C AT KINL/CWPL RESPECTIVELY TO -8C AT KGRB/KAPX. LOW INVERSION AROUND 920MB/2.6KFT MSL AT KINL/CWPL IS ANOTHER STRONG INHIBITOR FOR LES DEVELOPMENT. END RESULT IS A STRATUS/STRATOCU DECK...MAINLY OFF CNTRL/ERN LAKE SUPERIOR...AS AIRMASS MOVING OVER THE W LAKE PER 00Z KINL SOUNDING IS DRIER. && .DISCUSSION... (ISSUED AT 430 AM EST) QUIET DAY EXPECTED ACROSS THE FCST AREA TODAY. UPPER LOW OVER NEW YORK IS PROGGED TO DRIFT NW TODAY...BUT STILL REMAIN FAR ENOUGH TO THE E THAT -SN ON THE NW AND W FRINGE OF SYSTEM WILL REMAIN E OF THE FCST AREA. WITH LITTLE CHANGE IN 850MB TEMPS OR TEMPS NEAR THE INVERSION BASE (WARMING IF ANYTHING)...LES WILL NOT BE AN ISSUE TODAY. HOWEVER...OVER THE NE FCST AREA...THERE MAY BE A FEW FLURRIES OR SPOTTY VERY LIGHT -DZ (-FZDZ IN THE MORNING) AS MOIST LAYER WARMS ABOVE -10C...BUT POTENTIAL IS SO LIMITED WILL NOT MENTION. PLENTY OF STRATOCU SHOULD REMAIN TRAPPED UNDER INVERSION...MAINLY FROM AROUND THE KEWEENAW TO THE E HALF OF UPPER MI UNDER PERSISTENT NWRLY FLOW. WITH DRIER AIR FLOWING ACROSS WRN LAKE SUPERIOR...EXPECT SOME SUN OVER THE FAR W AND SW. EVEN OVER THE W WHERE SOME SUN WILL OCCUR...LOW MIXING HEIGHTS WILL KEEP TEMPS IN CHECK. IN GENERAL... EXPECT HIGHS IN THE 30S ACROSS THE BOARD. TONIGHT...UPPER LOW WILL REMAIN NEARLY STATIONARY TO THE E OF GEORGIAN BAY ALONG ONTARIO/QUEBEC BORDER AND ANY DEEP LAYER FORCING AROUND THE W SIDE OF SYSTEM WILL STILL REMAIN E OF THE FCST AREA. LOW-LEVEL TEMP STRUCTURE CHANGES LITTLE THOUGH THE NAM HINTS THAT THE MOISTURE DEPTH MAY IMPROVE A BIT OVER THE FAR E AS MOISTURE ADVECTS WWD. THIS WOULD MINIMIZE POTENTIAL OF ANY -DZ/-FZDZ AS MOISTURE WILL EXTEND TO AT LEAST -10C. IN LIGHT OF THE NAM OUTPUT...WILL CARRY A MENTION OF SOME FLURRIES TONIGHT OVER THE ERN FCST AREA. EXPECT DRY WEATHER TO CONTINUE ELSEWHERE. BEFORE HIGH/MID CLOUDS BEGIN TO INCREASE FROM THE NW...CLEAR/PARTLY CLOUDY SKIES SHOULD ALLOW TEMPS TO DROP INTO THE TEENS OVER THE W TONIGHT. ON THANKSGIVING DAY...ATTENTION WILL TURN TO SHORTWAVE CURRENTLY OVER BRITISH COLUMBIA/WA. IT WILL REACH WI/UPPER MI BY EVENING. THERE ARE SLIGHT DIFFERENCES IN THE TRACK OF SHORTWAVE (GFS AT SRN END OF GUIDANCE)...BUT MAJORITY OF GUIDANCE POINTS TO THE MAIN STRIPE OF SNOW/DEEP LAYER FORCING STREAKING ACROSS THE FCST AREA THU AFTN/EVENING. IT REALLY WON`T BE A SITUATION FOR ISENTROPIC ASCENT AIDED PCPN DUE TO LACK OF WAA. SO...THAT WILL BE A MISSING FACTOR TO BOOST SNOW ACCUMULATIONS. 850MB TEMPS OF -6 TO -8C ACROSS LAKE SUPERIOR WILL BE SUFFICIENT FOR A PERIOD OF SOME LAKE ENHANCEMENT UNDER W WINDS SHIFTING NWRLY. WITH RESPECTABLE DEEP LAYER FORCING... EXPECT A QUICK SHOT OF -SN WITH ACCUMULATIONS GENERALLY AROUND 1 INCH OVER THE FCST AREA. LAKE ENHANCEMENT SHOULD BOOST TOTALS A LITTLE...TO 2 MAYBE 3 INCHES OVER THE NW FCST AREA. LES WILL THEN DEVELOP IN THE WAKE OF THE SHORTWAVE THU NIGHT THOUGH 850MB TEMPS AREN`T ESPECIALLY LOW...ONLY DROPPING TO -10C. GFS SHOWS A MORE DRAMATIC LOSS OF DEEP MOISTURE OVER THE W WITH SUBSIDENCE/LOWERING INVERSION TO 4-5KFT THU NIGHT. WHILE NAM MAINTAINS A MUCH DEEPER MOISTURE PROFILE...DOWNWARD MOTION IS DOMINATING THE DENDRITIC SNOW GROWTH TEMP ZONE (DGZ). TO THE E...THE GFS MAINTAINS A DEEP MOISTURE PROFILE THRU THE NIGHT INTO FRI MORNING...BUT UPWARD MOTION IS CONFINED BELOW THE DGZ. WHILE THE GFS IS GENERALLY FAVORED PER HPC DISCUSSION...EVEN IF THE NAM IS CORRECT...ITS GUIDANCE DOESN`T FAVOR SIGNIFICANT SNOW ACCUMULATIONS IN THE LES REGIME BEHIND THE SHORTWAVE THU NIGHT INTO FRI AS MESOSCALE FORCED UPWARD MOTION REMAINS BELOW THE DGZ. THUS...OVERALL...IT DOESN`T LOOK LIKE LES WILL BE A BIG DEAL. PROBABLY LOOKING AT ACCUMULATIONS IN THE 1-2 TO MAYBE 3 INCH RANGE OVERNIGHT THU THRU FRI MORNING IN THE NW FLOW FAVORED SNOWBELTS. ANOTHER INCH POSSIBLE FRI AFTN...MAINLY E...AS DRYING PROGRESSES E INTO THE UPPER LAKES. BEYOND FRI...PATTERN REMAINS PERSISTENT WITH FCST AREA UNDER THE INFLUENCE OF ERN NAMERICA TROF. A SERIES OF SHORTWAVES WILL BE SLIDING SE INTO THE ERN TROF OVER THE WEEKEND THRU AT LEAST THE MIDDLE OF NEXT WEEK. AIRMASS WILL GENERALLY BE COLD ENOUGH TO SUPPORT LES WHICH WILL BE ENHANCED PERIODICALLY BY PASSING SHORTWAVES. HOWEVER...AT THIS TIME...IT DOES NOT APPEAR THAT ANY SIGNIFICANT SNOW WILL OCCUR. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... MVFR CIGS FROM LAKE EFFECT MOISTURE TRAPPED BELOW AN INVERSION ARE EXPECTED TO REMAIN IN PLACE THROUGH THE FORECAST PERIOD...THANKS TO NW WINDS CONTINUING A COOL AIR FLOW BELOW THE INVERSION GENERATING PERSISTENT LAKE EFFECT CLOUDS. THERE IS A POSSIBILITY FOR SOME SCATTERING OF THE CLOUDS AT CMX LATE THIS AFTN AS A BRIEF SURGE OF DRIER AIR MOVES IN. IT IS ALSO POSSIBLE THAT SKIES COULD BRIEFLY SCATTER OUT AT KSAW AROUND MIDNIGHT...BUT CONFIDENCE IS TOO LOW RIGHT NOW TO MENTION. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EASTERN HALF OF LAKE SUPERIOR WILL REMAIN UNDER THE INFLUENCE OF GRADIENT ASSOCIATED WITH SFC LOW NEAR LAKE ONTARIO. EXPECT NORTHERLY WINDS IN THE 15 TO 25 KNOT RANGE TO CONTINUE THROUGH TONIGHT... POSSIBLY INCREASING TO 30 KNOTS LATE THIS AFTERNOON AND EVENING AS THE LOW BEGINS LIFTING NORTHWARD INTO WESTERN QUEBEC. ACROSS WESTERN LAKE SUPERIOR...THE EFFECTS FROM SFC RIDGING WILL RESULT IN LIGHTER WINDS THERE. ON THU...THIS RIDGE IS EXPECTED TO DISSIPATE AS IT CROSSES LAKE SUPERIOR. LOOK FOR A LOW PRESSURE AREA TO FOLLOW IN THE WAKE OF THE RIDGE...CROSSING UPPER MICHIGAN THU AFTN. IN ITS WAKE...NORTHWEST WINDS OF 15 TO 25 KNOTS WILL DOMINATE LAKE SUPERIOR FOR LATER THU NIGHT INTO FRI. GUSTS COULD REACH 30 KNOTS ON EASTERN LAKE SUPERIOR LATE FRI. ANOTHER WEAKENING RIDGE OF HIGH PRESSURE IS EXPECTED TO CROSS LAKE SUPERIOR FRI NIGHT INTO SAT...ALLOWING WINDS TO RELAX BELOW 20 KNOTS. FOR SAT NIGHT INTO SUN...LOW PRESSURE DROPPING OUT OF THE NORTHERN PLAINS AND MOVING INTO LOWER MICHIGAN WILL CAUSE NORTH WINDS TO INCREASE TO 15 TO 25 KNOTS ON ALL OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...ROLFSON AVIATION...AJ MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBUQUERQUE NM 325 AM MST WED NOV 26 2008 ...WINTER WILL MAKE AN APPEARANCE ACROSS NEW MEXICO ON THURSDAY... .DISCUSSION... LATEST WATER VAPOR LOOP AND RUC80 ANALYSIS HAS AN UPPER LOW MOVING INTO SRN CALIFORNIA. MODELS ARE IN GOOD AGREEMENT ON THE TRACK AND STRENGTH OF THIS FEATURE AS IT TRAVERSES THE DESERT SOUTHWEST. MAIN FORECAST CHALLENGE WITH THIS SYSTEM WILL BE THE AMOUNT OF COLD AIR AND ITS IMPACT ON SNOW ACCUMULATIONS. BUT FIRST...ONE LAST TRANQUIL WEATHER DAY IS EXPECTED ACROSS NEW MEXICO. HOLIDAY TRAVELLERS WILL EXPERIENCE FILTERED SUNSHINE THROUGH THE AFTERNOON HOURS WITH HIGHS REMAINING ABOVE SEASONAL AVERAGES. NUMERICAL GUIDANCE HAS BEEN POOR THE LAST COUPLE OF DAYS AND CONTINUED TO SIDE ON THE COOLER SIDE OF THE TEMPERATURE ENVELOPE OVER THE WRN/CENTRAL ZONES BASED ON WEAK MIXING. THE FIRST SIGNIFICANT VORT MAX ASSOCIATED WITH THE UPPER LOW IS CURRENTLY INVADING SRN CALIFORNIA...PROVIDING WIDESPREAD MODERATE TO HEAVY RAINFALL. THIS WAVE WILL MIGRATE THROUGH SRN NV INTO NORTH CENTRAL AZ BY LATE IN THE DAY. THIS SHOULD MOISTEN UP THE COLUMN TO OUR WEST. THE NEXT NOTABLE VORT MAX OVER THE BAJA CALIFORNIA SHOULD TRACK NORTHEAST WED NIGHT AND INVADE NM DURING THE DAY ON THURSDAY. PLENTY OF MOISTURE ADVECTION WILL ACCOMPANY THIS WAVE...THEREFORE A WIDESPREAD PCPN EVENT IS LIKELY OVER THE WRN/CENTRAL PORTIONS OF THE FORECAST AREA. AS MENTIONED THE PAST SEVERAL DAYS...MODELS HAVE BEEN TRENDING WARMER AND WARMER...LIKELY DUE TO AN UNDERESTIMATE OF WARM AIR ADVECTION. MEANWHILE...THE MAIN LOW AND ITS ASSOCIATED COLD CORE ALOFT WILL WORK TOWARDS THE FOUR CORNERS REGION BY THU AFTERNOON. AS MOISTURE/PCPN INTERACTS WITH THE COOLER AIR...SNOW LEVELS WILL LOWER OVER THE NRN HIGH TERRAIN. TO COMPLICATE MATTERS...A SURFACE FRONT WILL TAKE RESIDENCE IN THE NE PLAINS BY LATE IN THE AFTERNOON. MUCH COLDER AIR IS EXPECTED IN ITS WAKE...WITH FALLING TEMPS LIKELY. MANY LOCALES IN THE NE MAY EXPERIENCE HIGH TEMPERATURES AROUND 18Z. RAIN WILL CHANGE TO SNOW IN THIS REGION BY LATE IN THE AFTERNOON AND MAY PLAY A FACTOR IN ACCUMULATING THU EVENING. CONTEMPLATED MANY OPTIONS WITH RESPECT TO HEADLINES AND OPTED TO PLAY THE CONSERVATIVE ROUTE... WHICH IS TO ALERT HOLIDAY TRAVELLERS ON THE POTENTIAL FOR SLIPPERY ROAD CONDITIONS. FEEL THAT NMZ002 IS A SLAM DUNK FOR ADVISORY TYPE SNOWFALL...WITH CONFIDENCE FAIRLY HIGH FOR NMZ004...ESPECIALLY OVER THE HIGHEST PEAKS. SNOW LEVELS WILL LIKELY BE FAIRLY HIGH INITIALLY AND LOWER AS THE DAY PROGRESSES. ACCUMULATING LEVEL COULD BE 1000 OR 1500 FEET HIGHER THAN SNOW LEVEL. WILL HOIST AN ADVISORY FOR THE 15Z/THU THROUGH 12Z/FRI PERIOD FOR THESE ZONES. MODERATE CONFIDENCE EXISTS WITH RESPECT NE PLAINS SOUTHWARD TO ABOUT A GLORIETA PASS TO CLAYTON LINE. GENERALLY UP TO ONE INCH ON GRASSY SURFACES MAY OCCUR EAST OF INTERSTATE 25...WITH 1 TO 3 INCHES POSSIBLE ALONG AND WEST. WILL LET DAY CREW EVALUATE THESE ZONES AS FRONTAL TIMING AND WHETHER PCPN WILL BE JUXTAPOSED WITH COLD AIR WILL BE A CRUCIAL FACTOR. TRANSITION PERIOD IS EXPECTED ON FRI AS ONE WEAKENING SYSTEM SHIFTS EAST AND ANOTHER UPR LEVEL DISTURBANCE DIGS OVER THE CENTRAL ROCKIES. ISOLATED TO SCATTERED POPS ARE EXPECTED IN THE REGION...HIGHEST OVER THE NRN/WRN MTS. MODELS ARE IN BETTER AGREEMENT WITH RESPECT TO THE WEEKEND FORECAST...BUT HAVE DECENT SPREAD WITHIN THE ENSEMBLE HEIGHT FIELDS. ATTM...IT APPEARS THE UPPER LEVEL DISTURBANCE WILL DIG INTO A CLOSED LOW OVER THE SRN BAJA...TOO FAR TO IMPACT NM. HOWEVER...UPR LEVEL N/NW FLOW COULD KEEP THE ERN PLAINS RELATIVELY ACTIVE. EVENING SHIFT MAINTAINED ISOLATED POPS THROUGH SUNDAY NIGHT AND THIS SEEMS REASONABLE. DPORTER && .AVIATION... VFR CONDITIONS PREVAIL AT MOST AIRPORTS NEXT 24 HOURS. AFTER ABOUT 07Z THU ACROSS FAR WESTERN NM NEAR AND WEST OF THE DIVIDE AND FROM THE CHUSKA MOUNTAINS SOUTHWARD...THIS INCLUDING KGUP...CIGS WILL LIKELY LOWER TO MVFR AND LOCALLY IFR RANGE AS TOP DOWN MOISTENING INCREASES AND FIRST OF THE PCPN BEGINS IN THESE AREAS. OTHERWISE NO AVIATION WEATHER HAZARDS FOR THE NEXT 24 HOURS. BROKEN TO OVERCAST MID AND HIGH LEVEL CLOUD COVER WILL CONTINUE THROUGH TONIGHT. NEXT AVIATION DISCUSSION SCHEDULED FOR 22Z. 43 && .FIRE WEATHER... TODAY A HIGH PRESSURE RIDGE MOVING ACROSS NM WILL PRODUCE LIGHT TRANSPORT WINDS AND WEAK MIXING...RESULTING IN WIDESPREAD POOR TO FAIR VENTILATION. MID AND UPPER LEVEL LOW PRESSURE SYSTEM APPROACHING FROM SOUTHERN CALIFORNIA WILL CONTINUE TO SPREAD SOME MID AND HIGH LEVEL MOISTURE OVER NEW MEXICO TODAY FOLLOWED BY INCREASING TOP DOWN MOISTENING TONIGHT THEN SCATTERED SHOWERS... ISOLATED THUNDERSTORMS AND HIGH TERRAIN SNOW SHOWERS ARRIVING WESTERN QUARTER TO THIRD OF THE STATE AFTER MIDNIGHT TONIGHT. PRECIPITATION WILL SPREAD OVER NORTH AND CENTRAL NM THANKSGIVING DAY AS A COLD FRONT HEADS SOUTH AND WEST W ACROSS THE EASTERN PLAINS AND THE UPPER LOW MOVES INTO NORTHWEST NM. ACCUMULATING SNOWFALL IS LIKELY ACROSS THE NORTHERN MTNS AND THE HIGHER PEAKS OF WEST CENTRAL NM. MEASURABLE TO SIGNIFICANT RAINFALL LIKELY ACROSS MOST OF THE REST OF NORTH...CENTRAL AND WESTERN SECTIONS...THOUGH BEHIND THE COLD FRONT FROM THE NORTHEAST HIGHLANDS INTO PORTIONS OF THE FAR NORTHEAST PLAINS SOME LOWER TERRAIN SNOW WILL ALSO BE POSSIBLE LATER THURSDAY AND THURSDAY NIGHT. PRECIPITATION AMOUNTS WEDNESDAY NIGHT INTO THURSDAY NIGHT WILL AVERAGE ONE TO THREE TENTHS OF AN INCH WITH SOMEWHERE IN THE RANGE OF FOUR TO EIGHT TENTHS OF AN INCH IN THE HIGHER TERRAIN OF THE NORTHWEST MTNS. VENTILATION WILL IMPROVE SLIGHTLY INTO FRIDAY AS STRONGER NORTHWEST TRANSPORT WINDS DEVELOP BEHIND THE DEPARTING LOW. THE POTENTIAL FOR A SECOND SIGNIFICANT WEATHER SYSTEM AFFECTING THE STATE BETWEEN SATURDAY AND MONDAY NOW APPEARS TO BE LESS SO THE CHANCE OF ACCUMULATING SNOWFALL THEN IS LOWER. 43 && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 57 35 49 32 / 5 30 70 50 GALLUP.......................... 56 34 44 30 / 10 50 80 40 GRANTS.......................... 61 32 46 29 / 5 20 90 30 GLENWOOD........................ 63 40 53 32 / 20 50 80 20 CHAMA........................... 54 25 39 23 / 0 10 90 80 LOS ALAMOS...................... 59 32 45 28 / 0 5 80 60 RED RIVER....................... 50 24 39 19 / 0 5 80 70 TAOS............................ 58 24 45 24 / 0 0 70 60 SANTA FE........................ 57 31 46 25 / 0 0 80 60 SANTA FE AIRPORT................ 58 35 47 30 / 0 0 80 50 ESPANOLA........................ 62 30 48 31 / 0 0 80 60 ALBUQUERQUE HEIGHTS............. 60 42 53 35 / 0 5 80 30 ALBUQUERQUE VALLEY.............. 62 38 54 33 / 0 5 80 30 ALBUQUERQUE FOOTHILLS........... 61 41 53 34 / 0 5 80 40 ALBUQUERQUE WEST MESA........... 61 40 52 35 / 0 5 80 30 SOCORRO......................... 64 38 57 33 / 0 5 70 10 SANDIA PARK/CEDAR CREST......... 57 34 45 24 / 0 5 80 40 MORIARTY/ESTANCIA............... 63 32 51 26 / 0 5 80 50 CARRIZOZO....................... 65 39 56 32 / 0 5 60 20 RUIDOSO......................... 59 38 49 29 / 0 5 60 10 RATON........................... 65 26 46 24 / 0 0 40 60 LAS VEGAS....................... 63 32 45 22 / 0 0 50 60 ROY............................. 62 33 46 25 / 0 0 40 60 CLAYTON......................... 65 31 46 26 / 0 0 20 60 SANTA ROSA...................... 68 39 55 32 / 0 0 50 30 TUCUMCARI....................... 68 35 55 31 / 0 0 30 40 FORT SUMNER..................... 70 38 59 33 / 0 0 40 20 CLOVIS.......................... 69 39 57 33 / 0 0 30 20 PORTALES........................ 69 35 58 32 / 0 0 30 20 ROSWELL......................... 71 42 67 38 / 0 0 30 10 && .ABQ WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 8 AM THURSDAY TO 5 AM MST FRIDAY FOR THE FOLLOWING ZONES...NMZ002-004. && $$ 46/43 nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1000 AM CST WED NOV 26 2008 .UPDATE... TEMPS TO THE NORTH OF SFC FRONT CONT TO STRUGGLE TO WARM AS FAST AS CURRENT FORECAST. WILL GO AHEAD AND LOWER HIGH TEMPS ACROSS MUCH OF THE AREA BASED ON TRENDS AND LATEST RUC. IT IS HARD TO SEE TEMPS IN THE 60S WITH CAA CONT THROUGHOUT THE DAY TODAY... ALBEIT WEAK CAA. UPDATES ON THEIR WAY. 30 ---------------------------------------- 551 AM CST WED NOV 26 2008 .AVIATION...MAIN CHALLENGE IS THE TIMING OF A WIND SHIFT. NORTH WINDS HAD DEVELOPED DOWN TO OKC AND HBR TO BEGIN THE PERIOD. USED OBSERVATIONAL TRENDS AND RUC TO TIME THE FRONT THROUGH OUN-LAW- SPS. WIND SPEEDS LIGHT...THOUGH...EXCEPT FOR A BRIEF PERIOD OF 12-14 KNOT WINDS AT CSM-HBR...WHERE MODEST COLD ADVECTION WILL AID MIXING THROUGH MIDDAY. && .PREV DISCUSSION... /ISSUED 457 AM CST WED NOV 26 2008/ DISCUSSION...ALTHOUGH MOST OF THE SEVEN DAY FORECAST IS DRY...WE DO EXPECT TO SEE SCATTERED RAIN LATE THURSDAY INTO FRIDAY...AND THE TEMPERATURE FORECAST IS UNUSUALLY DIFFICULT. THE CURRENT WEATHER PATTERN IS VERY CHALLENGING GIVEN THE FOLLOWING: SEVERAL FAST MOVING SHORTWAVE TROUGHS...INTERACTIONS BETWEEN THE NORTHERN AND SOUTHERN STREAM OF THE UPPER JET...AND INCONSISTENCIES AMONG MODEL SOLUTIONS. THIS MORNING WE CHOSE TO PIECE TOGETHER A FORECAST THAT USES SIGNALS FROM SEVERAL MODELS WHEN/WHERE THEY MATCH OBSERVATIONS AND PATTERN RECOGNITION. THE GFS AND NAM LOOK GOOD THROUGH FRIDAY MORNING. A WEAK FRONTAL BOUNDARY WAS LOCATED NEAR I-44 THIS MORNING...AND WILL DRIFT INTO THE RED RIVER VALLEY THIS AFTERNOON. INEXPLICABLY...THE MOS GUIDANCE KEEPS TEMPERATURES IN THE UPPER 60S WELL NORTH OF THE FRONT DESPITE NORTH WINDS IN NOVEMBER. NAM SOUNDINGS SUGGESTS LOWER 60S...SO WE LOADED THE NAM12 SFC TEMPS INTO THE GRIDDED FORECAST...AND THIS LOOKED REASONABLE. THE MOS COMES AROUND AND DOES A LITTLE BETTER JOB ON THANKSGIVING DAY...WITH THE FRONT STALLED TO OUR SOUTH...AND HIGHS IN THE 50S AND 60S WITHIN THE NORTHERLY LOW LEVEL FLOW REGIME. HIGH CLOUDS MAY INCREASE CONSIDERABLY LATE IN THE DAY...BUT LOW LEVEL MOISTURE STILL APPEARS TO BE DEFLECTED SOUTH AND EAST OF THE REGION BY PERSISTENT MID LEVEL WESTERLIES ALONG THE FRONTAL ZONE. THIS LACK OF LOW LEVEL MOISTURE MAKES THE PRECIPITATION FORECAST DIFFICULT. AT LEAST WE ARE CONFIDENT THAT THE ONSET SHOULD NOT TAKE PLACE UNTIL THURSDAY EVENING...BUT IT IS STILL DIFFICULT TO GAUGE HOW WIDESPREAD THE RAIN WILL BE. MODELS ARE INDICATING GREATER HEIGHT FALLS AND LIFT COMPARED TO PREVIOUS RUNS...BUT QPF APPEARS IN BANDS RATHER THAN A BROAD SWATH. INSPECTION SHOWS THE BANDED PRECIP IS ASSOCIATED WITH FRONTOGENESIS AT DIFFERENT HEIGHTS...ALONG WITH FORECAST SOUNDINGS WHICH SHOW SOME INSTABILITY AT MID LEVELS. THIS SHOULD GENERATE CONVECTIVE SHOWERS AND EVEN A FEW THUNDERSTORMS THURSDAY NIGHT...BUT A REINFORCING COLD FRONT WILL ARRIVE AT THE SAME TIME...SUCH THAT DRY AIR AT LOW LEVELS WILL CAUSE SOME EVAPORATION. THIS COULD LESSEN THE RAINFALL WHILE ALSO ENHANCING THE POST-FRONTAL WINDS. WE INCREASED POPS IN LINE WITH THE GFS MOS...BUT ALSO TRIED TO SHOW LOCALLY HIGHER CHANCES WITHIN THE BANDED STRUCTURES OVER NORTHERN OKLAHOMA...AND ALONG THE RED RIVER. BY FRIDAY...RAIN SHOULD TAPER OFF IN THE SOUTHEAST...AND COLD HIGH PRESSURE WILL SETTLE INTO THE REGION...KEEPING HIGHS IN THE 40S AND 50S. NORTHWEST FLOW SETS UP...BUT THE MODELS CONTINUE TO DIFFER IN HANDLING WAVES WITHIN THE FLOW...AND HOW MUCH COLD AIR WILL SLIDE DOWN THROUGH THE PLAINS. THE PATTERN IN THE OPERATIONAL GFS LOOKS REASONABLE...BUT THAT MODEL HAS TENDED TO MOVES SHORT WAVES TOO QUICKLY...AND IS TAPPING UNUSUALLY COLD AIR...CONSIDERING THAT THE SOURCE REGION IS NORTH OF THE GREAT LAKES...AND THAT AIR USUALLY SLIDES TO OUR EAST. WE ADJUSTED THE MOS TOWARD NUMBERS FROM THE GFS ENSEMBLE MEAN...WHICH IS NOT QUITE AS COLD. THE PERIOD OF REAL INTEREST...THOUGH OUT AT DAY 8...NEXT TUESDAY NIGHT/WEDNESDAY. THE ENSEMBLE AND THE ECMWF HAVE CONSISTENTLY INDICATED THAT A SHOT OF ARCTIC AIR WILL COME AT US FROM A MORE FAVORABLE TRAJECTORY OUT OF WESTERN CANADA. STAY TUNED. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 62 36 61 37 / 0 0 10 30 HOBART OK 64 34 60 36 / 0 0 20 30 WICHITA FALLS TX 69 38 65 39 / 0 0 10 50 GAGE OK 61 28 54 30 / 0 0 20 40 PONCA CITY OK 61 32 59 33 / 0 0 10 30 DURANT OK 74 41 68 40 / 0 0 10 40 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 24/22/22 BURKE ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 551 AM CST WED NOV 26 2008 .AVIATION...MAIN CHALLENGE IS THE TIMING OF A WIND SHIFT. NORTH WINDS HAD DEVELOPED DOWN TO OKC AND HBR TO BEGIN THE PERIOD. USED OBSERVATIONAL TRENDS AND RUC TO TIME THE FRONT THROUGH OUN-LAW- SPS. WIND SPEEDS LIGHT...THOUGH...EXCEPT FOR A BRIEF PERIOD OF 12-14 KNOT WINDS AT CSM-HBR...WHERE MODEST COLD ADVECTION WILL AID MIXING THROUGH MIDDAY. && .PREV DISCUSSION... /ISSUED 457 AM CST WED NOV 26 2008/ DISCUSSION...ALTHOUGH MOST OF THE SEVEN DAY FORECAST IS DRY...WE DO EXPECT TO SEE SCATTERED RAIN LATE THURSDAY INTO FRIDAY...AND THE TEMPERATURE FORECAST IS UNUSUALLY DIFFICULT. THE CURRENT WEATHER PATTERN IS VERY CHALLENGING GIVEN THE FOLLOWING: SEVERAL FAST MOVING SHORTWAVE TROUGHS...INTERACTIONS BETWEEN THE NORTHERN AND SOUTHERN STREAM OF THE UPPER JET...AND INCONSISTENCIES AMONG MODEL SOLUTIONS. THIS MORNING WE CHOSE TO PIECE TOGETHER A FORECAST THAT USES SIGNALS FROM SEVERAL MODELS WHEN/WHERE THEY MATCH OBSERVATIONS AND PATTERN RECOGNITION. THE GFS AND NAM LOOK GOOD THROUGH FRIDAY MORNING. A WEAK FRONTAL BOUNDARY WAS LOCATED NEAR I-44 THIS MORNING...AND WILL DRIFT INTO THE RED RIVER VALLEY THIS AFTERNOON. INEXPLICABLY...THE MOS GUIDANCE KEEPS TEMPERATURES IN THE UPPER 60S WELL NORTH OF THE FRONT DESPITE NORTH WINDS IN NOVEMBER. NAM SOUNDINGS SUGGESTS LOWER 60S...SO WE LOADED THE NAM12 SFC TEMPS INTO THE GRIDDED FORECAST...AND THIS LOOKED REASONABLE. THE MOS COMES AROUND AND DOES A LITTLE BETTER JOB ON THANKSGIVING DAY...WITH THE FRONT STALLED TO OUR SOUTH...AND HIGHS IN THE 50S AND 60S WITHIN THE NORTHERLY LOW LEVEL FLOW REGIME. HIGH CLOUDS MAY INCREASE CONSIDERABLY LATE IN THE DAY...BUT LOW LEVEL MOISTURE STILL APPEARS TO BE DEFLECTED SOUTH AND EAST OF THE REGION BY PERSISTENT MID LEVEL WESTERLIES ALONG THE FRONTAL ZONE. THIS LACK OF LOW LEVEL MOISTURE MAKES THE PRECIPITATION FORECAST DIFFICULT. AT LEAST WE ARE CONFIDENT THAT THE ONSET SHOULD NOT TAKE PLACE UNTIL THURSDAY EVENING...BUT IT IS STILL DIFFICULT TO GAUGE HOW WIDESPREAD THE RAIN WILL BE. MODELS ARE INDICATING GREATER HEIGHT FALLS AND LIFT COMPARED TO PREVIOUS RUNS...BUT QPF APPEARS IN BANDS RATHER THAN A BROAD SWATH. INSPECTION SHOWS THE BANDED PRECIP IS ASSOCIATED WITH FRONTOGENESIS AT DIFFERENT HEIGHTS...ALONG WITH FORECAST SOUNDINGS WHICH SHOW SOME INSTABILITY AT MID LEVELS. THIS SHOULD GENERATE CONVECTIVE SHOWERS AND EVEN A FEW THUNDERSTORMS THURSDAY NIGHT...BUT A REINFORCING COLD FRONT WILL ARRIVE AT THE SAME TIME...SUCH THAT DRY AIR AT LOW LEVELS WILL CAUSE SOME EVAPORATION. THIS COULD LESSEN THE RAINFALL WHILE ALSO ENHANCING THE POST-FRONTAL WINDS. WE INCREASED POPS IN LINE WITH THE GFS MOS...BUT ALSO TRIED TO SHOW LOCALLY HIGHER CHANCES WITHIN THE BANDED STRUCTURES OVER NORTHERN OKLAHOMA...AND ALONG THE RED RIVER. BY FRIDAY...RAIN SHOULD TAPER OFF IN THE SOUTHEAST...AND COLD HIGH PRESSURE WILL SETTLE INTO THE REGION...KEEPING HIGHS IN THE 40S AND 50S. NORTHWEST FLOW SETS UP...BUT THE MODELS CONTINUE TO DIFFER IN HANDLING WAVES WITHIN THE FLOW...AND HOW MUCH COLD AIR WILL SLIDE DOWN THROUGH THE PLAINS. THE PATTERN IN THE OPERATIONAL GFS LOOKS REASONABLE...BUT THAT MODEL HAS TENDED TO MOVES SHORT WAVES TOO QUICKLY...AND IS TAPPING UNUSUALLY COLD AIR...CONSIDERING THAT THE SOURCE REGION IS NORTH OF THE GREAT LAKES...AND THAT AIR USUALLY SLIDES TO OUR EAST. WE ADJUSTED THE MOS TOWARD NUMBERS FROM THE GFS ENSEMBLE MEAN...WHICH IS NOT QUITE AS COLD. THE PERIOD OF REAL INTEREST...THOUGH OUT AT DAY 8...NEXT TUESDAY NIGHT/WEDNESDAY. THE ENSEMBLE AND THE ECMWF HAVE CONSISTENTLY INDICATED THAT A SHOT OF ARCTIC AIR WILL COME AT US FROM A MORE FAVORABLE TRAJECTORY OUT OF WESTERN CANADA. STAY TUNED. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 62 36 61 37 / 0 0 10 30 HOBART OK 64 34 60 36 / 0 0 20 30 WICHITA FALLS TX 69 38 65 39 / 0 0 10 50 GAGE OK 61 28 54 30 / 0 0 20 40 PONCA CITY OK 61 32 59 33 / 0 0 10 30 DURANT OK 74 41 68 40 / 0 0 10 40 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 24/22/22 BURKE ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 316 PM EST WED NOV 26 2008 .SYNOPSIS... THE POWERFUL STORM AFFECTING MAINE WILL BEGIN TO EXIT THE AREA OVERNIGHT. WEAK HIGH PRESSURE WILL BUILD ACROSS THE REGION ON THANKSGIVING. A NEW LOW PRESSURE SYSTEM IS FORECAST TO APPROACH FRIDAY AND MOVE ACROSS THE REGION BY SATURDAY...BRINGING MOSTLY TO SNOW TO NORTHERN AREAS AND RAIN AND SNOW DOWNEAST. AFTER FAIR AND COLDER CONDITIONS ON SUNDAY...YET ANOTHER LOW WILL BRING A CHANCE OF SNOW AND RAIN TO THE REGION ON MONDAY. && .NEAR TERM /THROUGH THURSDAY/... MAIN FOCUS WILL BE THE TIMING OF PRECIP AND FOG POTENTIAL TONIGHT. A BLEND OF THE RUC AND CARWRF WAS USED TO START OUT AND THEN RAN W/A BLEND OF THE GFS AND SREF AFT 06Z INTO THANKSGIVING DAY FOR THE POP FIELDS. LATEST RADAR MOSAIC HADD PRECIP MOVING NORTHWARD AND SWINGING BACK TO THE W ACROSS THE FAR NORTHERN ZONES THIS EVENING. THE RUC AND CARWRF HANDLED THIS PRECIP WELL AS IT EXITS INTO NEW BRUNSWICK AFT 00Z. PRECIP TYPE A BIT TRICKY AS TEMPERATURES WILL BE RIGHT ON THE CUSP OF THE RAIN/SNOW TRANSITION. THINKING HERE IS THAT AREAS BACK TO NWRN AROOSTOOK COUNTY AND PLACES LIKE STOCKHOLM...NEW SWEDEN AND PORTAGE COULD SEE A BRIEF CHANGE OVER TO SNOW BEFORE IT ENDS. LATEST ANALYSIS SHOWED UPPER LOW PUSHING E AND COOLING FROM 850-700MBS ALREADY TAKING PLACE AND THIS IS PICKED WELL BY THE RUC AND CARWRF W/THE POTENTIAL FOR A CHANGE TO SOME SNOW IN THE AFOREMENTIONED AREAS. ANY NOW ACCUMULATIONS WILL BE LESS THAN AN INCH. LATEST SATL IMAGERY SHOWS BEST ENHANCEMENT RIGHT OVER THE EASTERN 3RD OF THE CWA W/CLEARING TAKING PLACE OVER THE CENTRAL AND DOWNEAST SECTIONS. THIS CLEARING LINE IS PUSHING N AND THE EXPECTATION IS THAT SOME CLEARING WILL OCCUR AS FAR NORTH AS CARIBOU AND PRESQUE. NOW...THIS CLEARING AND WINDS BECOMING LIGHT PLUS SOME LLVL COOLING COULD LEAD TO SOME FOG DEVELOPMENT AND STRATUS LATER TONIGHT ESP W/WET GROUND. DECIDED TO INCLUDE THE MENTION OF FOG FOR ALL AREAS. PREV FCST TEMPS LOOKED REAL GOOD W/THIS COOLING TREND. ONLY SLIGHT ADJUSTMENTS WERE MADE WHICH POINTS TO OVERNIGHT LOWS GOING DOWN TO THE MID AND UPPER 20S. ANOTHER CONCERN IS BLACK ICE DEVELOPMENT THIS EVENING AND OVERNIGHT. A SPECIAL WEATHER STATEMENT WILL BE ISSUED FOR THIS POTENTIAL. FOR THANKSGIVING DAY...MODEL SOUNDINGS SHOW PLENTY OF LLVL RH FROM 925-850MBS AND THIS MATCHES UP WELL W/12Z UA FROM TODAY. UPPER LEVEL LOW EXPECTED TO SPIN ACROSS THE QUEBEC PROVING W/A MID AND UPPER LEVEL TROF TO SWING ACROSS THE REGION. SOME FORCING NOTED TO ALLOW FOR SOME SNOW SHOWERS ESP ACROSS THE WEST AND NORTHWESTERN AREAS. THE GFS/SREF POPS LOOKED GOOD FOR THIS FEATURE W/30-40% POPS WEST AND NORTH AND 15-20%(ISOLATED) FOR THE CENTRAL HIGHLANDS. GMOS TEMPERATURES WERE USED SHOWING NEAR NORMAL TEMPERATURES. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... UPPER LEVEL TROF IS EXPECTED TO BE POSITIONED OVER THE STATE AT THE BEGINNING OF THIS FORECAST PERIOD. THIS WILL RESULT IN SNOW SHOWERS IN THE NORTHWESTERN PORTION OF THE FORECAST AREA. ANOTHER UPPER LEVEL SYSTEM ALONG WITH SURFACE LOW PRESSURE WILL APPROACH FROM THE WEST AND CROSS THE REGION FRIDAY. THIS SYSTEM WILL CROSS THE FORECAST AREA FRIDAY EVENING THEN MOVE OFF TO THE NORTHEAST SATURDAY MORNING. EXPECT LIGHT SNOW IN THE NORTH AS THIS SYSTEM MOVES THROUGH. IN SOUTHERN AREAS SNOW SHOULD CHANGE TO RAIN IN THE SOUTHERLY FLOW AHEAD OF THE LOW. THE UPPER LEVEL LOW WILL PASS ACROSS THE REGION SATURDAY BRINGING MORE SNOW SHOWERS. FOR POPS AND SKY COVER HAVE USED A BLEND OF THE NAM12 AND GFS40. HAVE USED OFFICE SNOW TOOL FOR SNOW ACCUMULATIONS BASED ON THE GFS. FOR TEMPERATURE...DEW POINT AND WIND HAVE USED GMOS. USED A BLEND OF GFS AND NAM FOR QPF. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... MODELS IN THE LONGER RANGE ARE IN FAIR AGREEMENT WITH TIMING AND TRACK OF THE NEXT LOW PRES SYSTEM TO AFFECT OUR FA ERLY NEXT WEEK. IN THIS SCENARIO...DRY AND COLDER WX SAT NGT THRU SUN WILL BE FOLLOWED UP INCREASING CLDS SUN NGT AS MOISTURE AHEAD OF A LARGE COMPLEX S/WV SYSTEM DIGGING INTO THE MIDWEST APCHS OUR FA. THIS SYSTEM IN THE UPPER AIR APPEARS TO BE FAIRLY SIMILAR TO THE ONE THAT AFFECTED OUR FA THE PAST COUPLE OF DAYS...WITH ONE IMPORTANT DIFFERENCE...A MUCH WEAKER BLOCKING FACTOR IN THE N ATLC. SUBSEQUENTLY...THE OVRRNG BAND OF PRECIP ASSOCIATED WITH THE SYSTEM WILL NOT BE IMPEDED FROM MOVING NWRD ACROSS THE FA BEGINNING VERY LATE SUN NGT AND CONTG INTO MON. PRECIP TYPE WILL BE TRICKY...WITH THE OPNL 12Z ECMWF AND THE 12Z GFSENS MEAN BOTH HINTING AT MORE SECONDARY LOW PRES ALG THE CNTRL NEW ENG COAST THAN THE OPNL 12Z GFS. HOWEVER...EVEN THE ERLY TRACKING SFC LOW MODELS INDICATE A CERTAIN AMOUNT OF CAPTURING OF THE SECONDARY SFC LOW MON AFT BY A DEVELPOING CLOSED 700 TO 500 MB VORTEX OVR THE ERN GREAT LKS. THIS WOULD BRING THE TRIPLE POINT INTO DOWNEAST AREAS NE TO ALG THE NERN ME/WRN NB BORDER. FOR NOW...WE WILL MENTION MSLY SN FOR NRN AND WRN PTNS OF THE FA...AND SN TRANSITIONING TO SN/RN OR ALL RN DOWNEAST BY MON AFT. GIVEN TIMING UNCERTAINTIES AND COLLABORATING THRESHOLDS WITH OUR NEIGHBORING OFFICE...FROM THIS POINT OUT IN THE FCST...IT WAS HARD TO JUSTIFY ABV HI CHC POPS ATTM...BUT THIS COULD END UP BEING A SHORT DURATION SIGNIFICANT PRECIP-WIND EVENT. FOLLOWING THE WARM ADVCN PRECIP BAND...MOST MODELS INDICATE SOME MID LVL DRY SLOTTING LATE MON INTO MON EVE BEFORE WHATS LEFT OF THE UPPER LOW FROM THE GREAT LKS TARCKS JUST N OF THE FA LATE MON NGT INTO TUE. THIS WOULD LIMIT MOST CLDS AND SN SHWRS TO NRN/WRN PTNS OF THE FA. OTHERWISE...SIGNIFICANTLY COLDER CONDITIONS WILL ARRIVE BEHIND THE DEPARTING LOW TUE...WITH SOME MODERATION WED. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... NEAR TERM: IFR/MVFR ACROSS THE NORTHERN TAF SITES TONIGHT W/THE POTENTIAL FOR SOME FOG DEVELOPMENT. CONDITIONS ACROSS THE NORTH WILL REMAIN MOSTLY IN THE MVFR CONDITIONS WHILE KBGR AND KBHB WILL SEE VFR FOR THANKSGIVING. SHORT TERM: EXPECT IFR CONDITIONS THURSDAY. IFR/MVFR CONDITIONS EXPECTED LATE FRIDAY INTO FRIDAY NIGHT AS LOW PRESSURE PASSES ACROSS THE STATE. VFR CONDITIONS EXPECTED SATURDAY AND SUNDAY. MVFR/IFR MONDAY IN RAIN AND SNOW. && .MARINE... NEAR TERM: DECIDED ON SCA FOR SEAS TONIGHT INTO THANKSGIVING DAY W/SWELL INCLUDED. SEAS 10-11 FT ATTM ARE EXPECTED TO SUBSIDE TONIGHT AND WILL CONTINUE THIS TREND RIGHT INTO THANKSGIVING DAY. WINDS WILL CONTINUE TO RUN 10-15 KT W/A 50-50 BLEND OF THE NAM12/GFS. SHORT TERM: HAVE USE A 50/50 BLEND OF THE NAM12 AND GFS40 FOR WIND GRIDS. WILL INCREASE WIND SPEED SLIGHTLY WITH SEA SURFACE TEMPERATURE A LITTLE WARMER THAN AIR TEMPERATURE. FOR WAVES: HAVE USED WNA/4. WAVE HEIGHTS LOOK REASONABLE...HOWEVER WILL MANUALLY ADJUST INTRA-COASTAL ZONE. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 PM EST THURSDAY FOR ANZ050>052. && $$ NEAR TERM...HEWITT SHORT TERM...MIGNONE LONG TERM...VJN AVIATION...HEWITT MARINE...HEWITT/MIGNONE me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 217 PM EST WED NOV 26 2008 .SYNOPSIS... HIGH PRESSURE BUILDS ACROSS THE SOUTHEASTERN STATES THIS AFTERNOON THROUGH THURSDAY NIGHT...AS LOW PRESSURE SPINS OVER EASTERN CANADA THROUGH LATE IN THE WEEK. A COLD FRONT CROSSES THE AREA LATER FRIDAY...AS LOW PRESSURE MOVES ACROSS THE SOUTHERN STATES OVER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... LATE MORNING ANALYSIS DEPICTS SFC HIGH PRES OVER THE SOUTHEASTERN CONUS...WITH A STRONG NEARLY VERTICALLY STACKED AREA OF LOW PRESSURE OVER SW QUEBEC. THIS FEATURE IS ALLOWING FOR DRY DEEP LAYER W/NW FLOW OVER THE MID-ATL. CYCLONIC FLOW CONTS TDA AS UPR LVL LOW SLOWLY SPINS NORTHWARD TWDS HUDSON BAY. ONLY SIGNIFICANT CHANGE TO GRIDS ATTM IS TO ALLOW FOR INCREASE IN CLOUD CVR OVER PIEDMONT IN ASSN WITH SCT-BKN MID-HI CLDS (5-8 KFT). RUC/NAM DOING PRETTY WELL WITH THESE CLDS THUS FAR THIS AM...AND SHOWS DRIER AIR FILTERING IN THIS AFTN AND DIMINISHING ANY LINGERING CLDS BY MID-AFTN. SO...TRIED TO MANIPULATE DIGITAL GRIDS TO REFLECT GRADUAL DECREASE IN CLDS THIS AFTN. OTW...DOWNSLOPING WND FLOW WL ALLOW FOR A PLEASANT AFTN ACROSS THE AREA. FORECAST TEMPS GENLY ON TRACK...U40S/NR50 N TO L50S S. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... FLAT H5 RIDGE WITH NEARLY ZONAL FLOW BUILDS INTO RGN TONIGHT THRU THU NITE. LOWS TONITE U20S-L30S. TURKEY DAY LOOKING RTHR PLEASANT UNDER A MSTLY SUNNY SKY. HIGHS M-U50S. TSCTNS SHOW SOME CLOUDS MOVG INTO RGN LATE THU NITE AHEAD OF APPRCHG CDFRNT. LOWS GNRLY IN THE 30S. DRY FRNTL BNDRY CROSSES RGN FRI. MILD WITH HIGHS 55-60. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...A PATTERN OF WEST COAST RIDGE AND EASTERN CANADA LOW CONTINUES IN THE EXTENDED WITH VARIOUS SHORT WAVES AFFECTING THE MID ATLANTIC STATES. CONFIDENCE IN MODELS NOT SUFFICIENT TO INCLUDE MORE THAN 20 PERCENT POPS AT THIS TIME. STARTING SAT NIGHT...LEANED TOWARD EURO WHICH BRINGS A COLD FRONT TO THE AREA SUN NIGHT WITH A COLD UPPER LOW BY MONDAY AND INDICATED SLIGHT CHANCE POPS THEN. NEW GFS INDICATES A STRONG WEATHER SYSTEM WITH A DEEP SURFACE LOW MOVING FROM THE TENNESSEE VALLEY TO MOVING INTO PENNSYLVANIA LATE SUN AND MON. WITH EITHER SCENARIO...TEMPERATURES MAY BE BORDERLINE FOR MIXED RAIN AND SNOW SHOWERS BUT ONLY INCLUDED RAIN SHOWERS AT THIS POINT. ANY PRECIPITATION AMOUNTS WITH A SYSTEM LIKE THIS ONE LATE SUN AND MON WOULD BE LIGHT. HPC INDICATES A FAST MOVING FRONT WHICH WILL CROSS THE PACIFIC NORTHWEST MON WILL APPROACH OUR AREA BY WED. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... MODEL SOUNDINGS AND OBSERVATIONS WERE USED TO FORECAST FOR MAINLY SCT CLOUD LAYERS TODAY. INDICATIONS ARE FOR MAINLY CLEAR SKIES LATE TONIGHT THROUGH 18Z THU. WINDS SHOULD STAY GENERALLY 12 KNOTS OR LESS. HIGH PRESSURE DOMINATES THROUGH THU NIGHT. A FRONT ASSOCIATED WITH A SURFACE LOW IN THE NORTHERN GREAT LAKES WILL MOVE THROUGH FRI AFTN/EVENING WHICH SHOULD COME THORUGH DRY. AT THIS POINT. AN AREA OF LOW PRESSURE IN THE SOUTHEASTERN STATES WILL BRING A SLIGHT CHANCE FOR SHOWERS TO THE THE SOUTHERN PORTION OF THE AREA FRI NIGHT AND SAT. LOWER CEILINGS ARE POSSIBLE WITH AN UPPER LEVEL LOW PRESSURE SYSTEM BY LATE SUN OR MON. && .MARINE... SCA HAS EXPIRED OVER THE BAY WATERS AS WIND GRADIENT HAS SUBSIDED UNDER CRITERIA. CALMER CONDS THEN EXPECTED ALL WTRS LATER TDY INTO ERLY FRI...AS THE CNTR OF HI PRES BLDS BY JUST TO OUR S THEN OFF THE SE CST. A COLD FRNT WILL AFFECT THE AREA FRI AFTN INTO FRI EVENG...BUT SCA CONDS ARE NOT EXPECTED. HI PRES WILL RETURN FOR LATER FRI NGT THRU AT LEAST SAT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...MAM NEAR TERM...MAM/MPR SHORT TERM...MPR LONG TERM...LSA AVIATION...LSA MARINE...CCW/TMG md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1130 AM CST WED NOV 26 2008 .AVIATION... ONLY MID AND HIGH CLOUDS EXPECTED OVER THE AVIATION SITES OVER THE 24 HOURS. THIS MORNING/S WIND SHIFT HAS ALREADY MOVED THROUGH ALL OF THE AREA TAF SITES BRINGING THE NORTHERLY WINDS. THE NEXT FRONT WILL MOVE THROUGH KGAG AND KWWR BEFORE 18Z THURSDAY INCREASING THE SPEED OF THE NORTH WINDS SOMEWHAT. && .PREV DISCUSSION... /ISSUED 1000 AM CST WED NOV 26 2008/ UPDATE... TEMPS TO THE NORTH OF SFC FRONT CONT TO STRUGGLE TO WARM AS FAST AS CURRENT FORECAST. WILL GO AHEAD AND LOWER HIGH TEMPS ACROSS MUCH OF THE AREA BASED ON TRENDS AND LATEST RUC. IT IS HARD TO SEE TEMPS IN THE 60S WITH CAA CONT THROUGHOUT THE DAY TODAY... ALBEIT WEAK CAA. UPDATES ON THEIR WAY. 30 ---------------------------------------- 551 AM CST WED NOV 26 2008 AVIATION...MAIN CHALLENGE IS THE TIMING OF A WIND SHIFT. NORTH WINDS HAD DEVELOPED DOWN TO OKC AND HBR TO BEGIN THE PERIOD. USED OBSERVATIONAL TRENDS AND RUC TO TIME THE FRONT THROUGH OUN-LAW- SPS. WIND SPEEDS LIGHT...THOUGH...EXCEPT FOR A BRIEF PERIOD OF 12-14 KNOT WINDS AT CSM-HBR...WHERE MODEST COLD ADVECTION WILL AID MIXING THROUGH MIDDAY. PREV DISCUSSION... /ISSUED 457 AM CST WED NOV 26 2008/ DISCUSSION...ALTHOUGH MOST OF THE SEVEN DAY FORECAST IS DRY...WE DO EXPECT TO SEE SCATTERED RAIN LATE THURSDAY INTO FRIDAY...AND THE TEMPERATURE FORECAST IS UNUSUALLY DIFFICULT. THE CURRENT WEATHER PATTERN IS VERY CHALLENGING GIVEN THE FOLLOWING: SEVERAL FAST MOVING SHORTWAVE TROUGHS...INTERACTIONS BETWEEN THE NORTHERN AND SOUTHERN STREAM OF THE UPPER JET...AND INCONSISTENCIES AMONG MODEL SOLUTIONS. THIS MORNING WE CHOSE TO PIECE TOGETHER A FORECAST THAT USES SIGNALS FROM SEVERAL MODELS WHEN/WHERE THEY MATCH OBSERVATIONS AND PATTERN RECOGNITION. THE GFS AND NAM LOOK GOOD THROUGH FRIDAY MORNING. A WEAK FRONTAL BOUNDARY WAS LOCATED NEAR I-44 THIS MORNING...AND WILL DRIFT INTO THE RED RIVER VALLEY THIS AFTERNOON. INEXPLICABLY...THE MOS GUIDANCE KEEPS TEMPERATURES IN THE UPPER 60S WELL NORTH OF THE FRONT DESPITE NORTH WINDS IN NOVEMBER. NAM SOUNDINGS SUGGESTS LOWER 60S...SO WE LOADED THE NAM12 SFC TEMPS INTO THE GRIDDED FORECAST...AND THIS LOOKED REASONABLE. THE MOS COMES AROUND AND DOES A LITTLE BETTER JOB ON THANKSGIVING DAY...WITH THE FRONT STALLED TO OUR SOUTH...AND HIGHS IN THE 50S AND 60S WITHIN THE NORTHERLY LOW LEVEL FLOW REGIME. HIGH CLOUDS MAY INCREASE CONSIDERABLY LATE IN THE DAY...BUT LOW LEVEL MOISTURE STILL APPEARS TO BE DEFLECTED SOUTH AND EAST OF THE REGION BY PERSISTENT MID LEVEL WESTERLIES ALONG THE FRONTAL ZONE. THIS LACK OF LOW LEVEL MOISTURE MAKES THE PRECIPITATION FORECAST DIFFICULT. AT LEAST WE ARE CONFIDENT THAT THE ONSET SHOULD NOT TAKE PLACE UNTIL THURSDAY EVENING...BUT IT IS STILL DIFFICULT TO GAUGE HOW WIDESPREAD THE RAIN WILL BE. MODELS ARE INDICATING GREATER HEIGHT FALLS AND LIFT COMPARED TO PREVIOUS RUNS...BUT QPF APPEARS IN BANDS RATHER THAN A BROAD SWATH. INSPECTION SHOWS THE BANDED PRECIP IS ASSOCIATED WITH FRONTOGENESIS AT DIFFERENT HEIGHTS...ALONG WITH FORECAST SOUNDINGS WHICH SHOW SOME INSTABILITY AT MID LEVELS. THIS SHOULD GENERATE CONVECTIVE SHOWERS AND EVEN A FEW THUNDERSTORMS THURSDAY NIGHT...BUT A REINFORCING COLD FRONT WILL ARRIVE AT THE SAME TIME...SUCH THAT DRY AIR AT LOW LEVELS WILL CAUSE SOME EVAPORATION. THIS COULD LESSEN THE RAINFALL WHILE ALSO ENHANCING THE POST-FRONTAL WINDS. WE INCREASED POPS IN LINE WITH THE GFS MOS...BUT ALSO TRIED TO SHOW LOCALLY HIGHER CHANCES WITHIN THE BANDED STRUCTURES OVER NORTHERN OKLAHOMA...AND ALONG THE RED RIVER. BY FRIDAY...RAIN SHOULD TAPER OFF IN THE SOUTHEAST...AND COLD HIGH PRESSURE WILL SETTLE INTO THE REGION...KEEPING HIGHS IN THE 40S AND 50S. NORTHWEST FLOW SETS UP...BUT THE MODELS CONTINUE TO DIFFER IN HANDLING WAVES WITHIN THE FLOW...AND HOW MUCH COLD AIR WILL SLIDE DOWN THROUGH THE PLAINS. THE PATTERN IN THE OPERATIONAL GFS LOOKS REASONABLE...BUT THAT MODEL HAS TENDED TO MOVES SHORT WAVES TOO QUICKLY...AND IS TAPPING UNUSUALLY COLD AIR...CONSIDERING THAT THE SOURCE REGION IS NORTH OF THE GREAT LAKES...AND THAT AIR USUALLY SLIDES TO OUR EAST. WE ADJUSTED THE MOS TOWARD NUMBERS FROM THE GFS ENSEMBLE MEAN...WHICH IS NOT QUITE AS COLD. THE PERIOD OF REAL INTEREST...THOUGH OUT AT DAY 8...NEXT TUESDAY NIGHT/WEDNESDAY. THE ENSEMBLE AND THE ECMWF HAVE CONSISTENTLY INDICATED THAT A SHOT OF ARCTIC AIR WILL COME AT US FROM A MORE FAVORABLE TRAJECTORY OUT OF WESTERN CANADA. STAY TUNED. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 60 36 61 37 / 0 0 10 30 HOBART OK 64 34 60 36 / 0 0 20 30 WICHITA FALLS TX 65 38 65 39 / 0 0 10 50 GAGE OK 62 28 54 30 / 0 0 20 40 PONCA CITY OK 61 32 59 33 / 0 0 10 30 DURANT OK 71 41 68 40 / 0 0 10 40 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 01/01/01 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 1143 AM CST WED NOV 26 2008 .AVIATION... HIGH CLOUDS WILL CONTINUE THROUGH THE PERIOD WITH VFR PREVAILING AT METROPLEX SITES. SLIGHTLY HIGHER MOISTURE AT KACT WILL RESULT IN A CHANCE OF MVFR CIGS FROM 10-14Z. CONFIDENCE IS LOW DUE TO DISAGREEMENTS IN THE MODELS ON HOW FAR NORTHWEST BETTER MOISTURE WILL MAKE IT INTO NORTH TEXAS. HAVE GONE WITH JUST A TEMPO GROUP ATTM. OTHERWISE RUC/NAM FORECASTS DEPICT SW WINDS THIS AFTERNOON AT METROPLEX SITES...BECOMING VERY LIGHT NW THIS EVENING AND OVERNIGHT AS A WEAK FRONT MOVES INTO THE TRACON. 92 && .UPDATE... 1125 AM WILL LOWER HIGH TEMPERATURES A CATEGORY ACROSS THE AREA. THICKER CLOUDS HAVE LIMITED THE WARMING A BIT. 84 && .PREV DISCUSSION... /ISSUED 350 AM CST WED NOV 26 2008/ AN ACTIVE WEATHER PATTERN IS DEVELOPING FOR THE NEXT SEVEN DAYS WITH A SERIES OF COLD FRONTS FORECAST TO PASS THROUGH NORTH TEXAS... BUT A DRY FORECAST WILL ACCOMPANY THESE FRONTS EXCEPT FOR THE THURSDAY NIGHT TO FRIDAY TIME FRAME. BUT BEFORE THEN...UPPER LEVEL RIDGING...SOUTHWEST WINDS...AND A WARMER ATMOSPHERIC COLUMN TODAY WILL RESULT IN A FAIRLY WARM DAY WITH TEMPERATURES 10-15 DEGREES ABOVE NORMAL. HAVE GONE SEVERAL DEGREES ABOVE MOS GUIDANCE FOR TODAY GIVEN THE CONDITIONS MENTIONED ABOVE AND EXPECTED BREAKS IN THE CIRRUS CLOUDS LATER TODAY. A WEAK FRONT WILL SLIDE INTO THE NORTHWESTERN PORTIONS OF NORTH TEXAS THIS EVENING BUT WILL REMAIN NEARLY STATIONARY NORTH OF INTERSTATE 20 TONIGHT WITH LITTLE IMPACTS/EFFECTS EXPECTED. HOWEVER...TEMPERATURES TONIGHT BEHIND THE FRONT SHOULD DROP INTO THE LOWER 40S WHILE LOCATIONS SOUTH OF THE FRONT WILL BE WARM WITH VALUES IN THE 50S AND UPPER 40S. UPPER LEVEL LOW THAT IS CURRENTLY OFF THE CALIFORNIA COAST WILL MOVE INTO OKLAHOMA FRIDAY MORNING AND WITH THIS SLOWER SOLUTION...HAVE REMOVED MOST POPS FOR THURSDAY AND WARMED TEMPERATURES FROM THE PREVIOUS FORECAST. WEAK RIDGING ALOFT WILL CONTINUE OVER THE REGION ON THURSDAY WITH SOUTHWEST WINDS AND WARM TEMPERATURES ALOFT AGAIN. AS THE UPPER LEVEL SYSTEM APPROACHES WEST TEXAS ON THURSDAY NIGHT...TRUE COLD FRONT WILL DRIVE SOUTH ARRIVING IN NORTH TEXAS ON THURSDAY NIGHT. RAIN WILL DEVELOP ALONG THE FRONT...FIRST IN WEST AND CENTRAL TEXAS AND THEN MOVE ACROSS NORTH TEXAS FROM WEST TO EAST. BEST TIMING FOR RAIN LOOKS TO BE FROM MIDNIGHT TO SUNRISE AS THE FRONT MOVES THROUGH THE REGION. THE AREAL EXTENT OF THE RAIN IS STILL UNCERTAIN AT THIS TIME BUT THERE ARE SUGGESTIONS THAT MOST OF THE PRECIPITATION WILL FALL ALONG AND SOUTH OF INTERSTATE 20. HOWEVER...UNCERTAINTY IN THE MODELS KEEPS ME FROM TRYING TO BE TOO SPECIFIC WITH POPS AT THIS TIME EXCEPT TO SHOW A TREND FROM WEST TO EAST. PRECIPITATION WILL END ON FRIDAY MORNING AS THE FRONT CONTINUES TO PUSH SOUTH OF THE REGION. AS THE UPPER LEVEL LOW SLIDES ACROSS OKLAHOMA...IT WILL BE ABSORBED BY A DIGGING TROUGH ACROSS THE EASTERN CONUS. THIS TROUGH WILL DOMINATE THE EASTERN CONUS THROUGH AT LEAST NEXT TUESDAY...LEAVING DRY NORTHWESTERLY FLOW OVER NORTH TEXAS IN THE EXTENDED. AT THIS TIME...CONTINUE TO SIDE WITH THE ECMWF AND CANADIAN SOLUTIONS WHICH KEEP THE WESTERN EXTENT OF THE TROUGH EAST OF NORTH TEXAS...UNLIKE THE GFS WHICH BROADENS THE TROUGH OVER NORTH TEXAS AND PULLS ADDITIONAL ENERGY ACROSS NORTH TEXAS THIS WEEKEND. WITH THIS ENERGY...IT TRIES TO DEVELOP ADDITIONAL PRECIPITATION ON SUNDAY BUT ALL OTHER MODELS SUGGEST A DRY FORECAST. UNDER THE INFLUENCE OF NORTHWEST FLOW ALOFT...ANOTHER FOUR FRONTS WILL SLIDE ACROSS NORTH TEXAS BETWEEN SATURDAY AND WEDNESDAY. EACH FRONT WILL HELP TO HOLD TEMPERATURES IN THE EXTENDED PERIOD NEAR OR BELOW NORMAL VALUES. MOISTURE RETURN WILL NOT HAVE TIME TO ESTABLISH BETWEEN EACH FRONT AND WITH THE NORTHWEST FLOW ALOFT...THE FORECAST IN THE EXTENDED LOOKS DRY. 82/JLD && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 73 48 72 44 57 / 0 5 10 50 20 WACO, TX 72 52 74 48 58 / 0 5 20 50 30 PARIS, TX 70 44 69 43 57 / 0 5 10 50 30 DENTON, TX 73 41 72 42 59 / 0 5 10 50 20 MCKINNEY, TX 71 43 71 42 58 / 0 5 10 50 20 DALLAS, TX 73 51 74 46 58 / 0 5 10 50 20 TERRELL, TX 71 48 72 46 57 / 0 5 10 50 30 CORSICANA, TX 71 53 72 47 59 / 0 5 10 50 30 TEMPLE, TX 74 54 75 49 59 / 0 5 20 50 30 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 92/84 tx