000 FXUS61 KBUF 231146 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 646 AM EST MON NOV 23 2009 .SYNOPSIS... A LARGE AREA OF HIGH PRESSURE EXTENDING FROM NORTHERN NEW ENGLAND INTO THE GREAT LAKES WILL RETREAT TO THE CANADIAN MARITIMES TODAY. A WEAK MID LEVEL DISTURBANCE WILL BRING AN INCREASE IN CLOUD COVER AND PERHAPS A FEW LIGHT SHOWERS TO THE REGION TONIGHT AND TUESDAY. A WEAK RIDGE OF HIGH PRESSURE WILL BRING A RETURN TO MAINLY DRY WEATHER TUESDAY NIGHT BEFORE AN AREA OF LOW PRESSURE MOVES INTO THE GREAT LAKES LATER WEDNESDAY BRINGING THE NEXT CHANCE OF SHOWERS. ABOVE AVERAGE TEMPERATURES WILL CONTINUE THROUGH MUCH OF THIS WEEK BEFORE A SIGNIFICANT COOL DOWN AND POSSIBLY A CHANGE TOWARDS MORE WINTRY WEATHER BY NEXT WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... FOR THE MOST PART SKIES ARE CLEAR ACROSS WESTERN AND CENTRAL NEW YORK EARLY THIS MORNING. 11-3 MICRON IMAGERY SHOWING AREA OF INCREASING STRATUS WORKING NORTHWEST INTO THE SOUTHERN TIER OF NEW YORK STATE IN WEAK LOW LEVEL SOUTHEASTERLY FLOW. THIS TREND WILL LIKELY CONTINUE THROUGH THE REST OF THE EARLY MORNING HOURS WITH LOW STRATUS PUSHING ACROSS MOST OF SOUTHERN NEW YORK STATE. AREAS WHICH REMAIN CLEAR WILL LIKELY EXPERIENCE SOME PATCHY FOG THROUGH SUNRISE. ONCE ANY STRATUS BURNS OFF THIS MORNING...MOST OF THE REMAINDER OF THE DAY TODAY LOOKS TO BE IN FINE SHAPE AS STRONG 1035+ MB HIGH CENTERED OVER NORTHERN NEW ENGLAND SLIDES EASTWARD. CLOUDINESS WILL GRADUALLY INCREASE FROM SOUTH TO NORTH THIS AFTERNOON AS COMPLEX LOW PRESSURE SYSTEM LIFTS NORTH OUT OF THE SOUTHEASTERN STATES. TEMPERATURES TODAY SHOULD BE SIMILAR TO SUNDAY WITH LITTLE CHANGE IN AIR MASS...SREF/MOS BIAS CORRECTED NUMBERS SUGGESTING HIGHS IN THE LOWER TO MID 50S. THE LOW LIFTING THROUGH THE SOUTHEAST LOOKS TO GET SHEARED TO THE NORTHEAST AND EAST TONIGHT FORMING A COASTAL LOW. THIS SHOULD TAKE MOST OF THE DEEPER MOISTURE WITH IT. THERE IS STILL A QUESTION ON HOW FAR NORTH AND WEST THE PRECIPITATION SHIELD WILL GET ACROSS OUR AREA WITH THE COASTAL LOW PUSHING TO NEAR CAPE COD BY TUESDAY MORNING. AT THIS POINT...WILL REMAIN CLOSE TO CONTINUITY AND SUGGEST A LOW CHANCE FOR SHOWERS ACROSS SOUTH AND EASTERN AREAS WITH A SLIGHT CHANCE EXTENDING ACROSS NORTHWEST SECTIONS. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AT THE START OF THE PERIOD A WEAK MID LEVEL TROUGH WILL BE LIFTING NORTHEAST ACROSS THE AREA. MODEL GUIDANCE HAS HAD A DIFFICULT TIME WITH THIS FEATURE IN RESPECT TO TIMING AND PRECIP POTENTIAL. LATEST 00Z/23 GUIDANCE IS BACKING OFF ON QPF/POPS AND ONCE AGAIN FOCUSING MOST OF THE STRONGER FORCING AND MOISTURE TRANSPORT ALONG THE COASTAL PLAIN NEAR A DEVELOPING LOW OFFSHORE. TO THE WEST OF THE APPALACHIANS...THIS WILL JUST LEAVE A WEAK SURGE OF MOISTURE LIFTING NORTH ACROSS THE AREA...WITH ONLY WEAK MID LEVEL LIFT FROM A DE-AMPLIFYING MID LEVEL TROUGH. WILL BACK OFF ON POPS AND GO LOW CHANCE FOR TUESDAY FROM THE SOUTHERN TIER THROUGH THE FINGER LAKES INTO THE TUG HILL REGION. HAVE KEPT THE NIAGARA FRONTIER AND SAINT LAWRENCE VALLEY DRY WITH LESS NORTHERN EXTENT ON LATEST MODEL GUIDANCE. ANY PRECIP THAT DOES FALL WILL BE LIGHT...WITH QPF LESS THAN A TENTH OF AN INCH. THIS SYSTEM WILL BRING AN INCREASE IN CLOUD COVER TO THE ENTIRE REGION WITH LOW LEVEL MOISTURE BECOMING TRAPPED UNDER A SUBSIDENCE INVERSION ONCE AGAIN...A COMMON OCCURRENCE AT THIS TIME OF YEAR. ANY PRECIP WILL END BY TUESDAY NIGHT WITH A WEAK RIDGE OF HIGH PRESSURE BUILDING OVER THE LOWER LAKES...BUT CLOUDS WILL REMAIN FOR MOST OF THE REGION. ON WEDNESDAY AN AREA OF LOW PRESSURE WILL LIFT FROM THE MID MISSISSIPPI VALLEY INTO THE CENTRAL LAKES. THE WARM ADVECTION WING AHEAD OF THIS SYSTEM WILL LIFT ACROSS THE LOWER LAKES THROUGH THE COURSE OF THE DAY. LATEST MODEL GUIDANCE IS SLOWING THE TIMING OF THIS FEATURE...AND ALSO SHIFTING THE TRACK MORE TO THE NORTHWEST. THE NET RESULT WILL BE A MORE OPTIMISTIC FORECAST FOR WEDNESDAY... AND WILL NEED TO BACK OFF ON POPS AS A RESULT. IN FACT...THE 00Z NAM HOLDS MOST OF THE PRECIP OFF UNTIL WEDNESDAY NIGHT. WILL GO WITH CHANCE POPS FOR NOW...INCREASING FROM WEST TO EAST THROUGH THE DAY. 925MB TEMPS RISE TO +6C...AND SOUTHERLY DOWNSLOPE WINDS SHOULD BOOST TEMPS INTO THE UPPER 50S IN THE LOWER ELEVATIONS. A FEW PLACES IN THE GENESEE VALLEY AND CENTRAL NY MAY ECLIPSE 60. LOW TO MID 50S WILL DO IT FOR THE HIGHER TERRAIN OF THE SOUTHERN TIER AND NORTH COUNTRY WITHOUT THE BENEFIT OF COMPRESSIONAL DOWNSLOPE WARMING. WEDNESDAY NIGHT THE SURFACE LOW WILL REMAIN NEARLY IN PLACE OVER THE UPPER GREAT LAKES AS A COMPLEX MID LEVEL EVOLUTION TAKES PLACE... WITH ANOTHER SHORTWAVE DROPPING INTO THE WESTERN PERIPHERY OF THE DEVELOPING MID LEVEL TROUGH. AGAIN THE NEXT RESULT WAS TO SLOW THE FORWARD PROGRESS OF THIS SYSTEM FROM PREVIOUS RUNS...AND SHOULD KEEP THE BULK OF ORGANIZED PRECIP NORTH AND WEST OF THE AREA. WILL KEEP CHANCE POPS GOING FOR NOW...BUT MUCH OF THIS PERIOD MAY END UP BEING RAIN FREE. && .LONG TERM /THURSDAY THROUGH SUNDAY/... A RELATIVELY WEAK SURFACE LOW WILL REMAIN OVER THE UPPER LAKES ON THANKSGIVING. GIVEN THE POSITION OF THE SURFACE AND MID LEVEL FEATURES...EXPECT THE HOLIDAY TO BE MAINLY RAIN FREE. WAS TEMPTED TO REMOVE POPS ALTOGETHER...BUT FOR NOW WILL BACK OFF TO LOW CHANCE TO ACCOUNT FOR THE POTENTIAL OF FUTURE MODEL CHANGES. IF THE CURRENT TREND CONTINUES...POPS MAY BE REMOVED FOR THANKSGIVING. IT NOW APPEARS COLDER AIR WILL HOLD OFF UNTIL FRIDAY...SO THE ABOVE AVERAGE TEMPERATURES WILL CONTINUE THROUGH THE HOLIDAY. THINGS GET MUCH MORE INTERESTING BY DAYS 5-7. A POTENT MID LEVEL VORTEX IS FORECAST TO DROP INTO THE OHIO VALLEY THURSDAY NIGHT... THEN MOVE TOWARDS THE EASTERN SEABOARD FRIDAY AND FRIDAY NIGHT. AT THE SAME TIME...A SOUTHERN STREAM SYSTEM WILL ROUND THE BASE OF THE DEVELOPING TROUGH...WITH THE TWO FEATURES COMING IN CLOSE PROXIMITY ALONG THE NORTHERN MID ATLANTIC COAST. STRONG MID LEVEL FORCING MOVING ATOP A TIGHT BAROCLINIC ZONE ALONG THE COAST MAY RESULT IN STRONG COASTAL CYCLOGENESIS...WITH THE RESULTING SURFACE LOW LIFTING NORTH ACROSS NEW ENGLAND LATE FRIDAY THROUGH SATURDAY. UTILIZING A POTENTIAL VORTICITY ANALYSIS...IT CAN BE SEEN THAT THE SYSTEM RESPONSIBLE FOR THIS POTENTIAL IS STILL OVER THE NORTH PACIFIC... APPARENT IN MOISTURE CHANNEL IMAGERY OFFSHORE OF BRITISH COLUMBIA. UNTIL THIS SYSTEM MOVES INTO THE NORTH AMERICAN RADIOSONDE NETWORK...MODEL FORECASTS SHOULD BE VIEWED WITH CAUTION. LOOKING AT THE LATEST 00Z/23 MODELS...THE GFS CONTINUES TO BRING A STRONG COASTAL LOW WELL INLAND ACROSS NEW ENGLAND. THE ECMWF IS WEAKER AND FARTHER EAST...WHILE THE CANADIAN GEM CONTINUES TO SHOW A VERY DIFFERENT EVOLUTION WITH LITTLE COASTAL CYCLOGENESIS...BRINGING IN COLDER TEMPS AND WRAP AROUND PRECIP ALMOST 24 HOURS FASTER THAN OTHER MODEL GUIDANCE. THE 00Z/23 NAVY NOGAPS IS SIMILAR TO THE ECMWF. AT THIS TIME RANGE...LITTLE DETAIL WILL BE OFFERED IN THE GRIDS WITH JUST CHANCE POPS FOR THE ENTIRE PERIOD. EXPECT PRECIP TO BE MAINLY RAIN THROUGH FRIDAY...BEFORE COLDER AIR ALOFT WRAPS INTO THE AREA AND BRINGS INCREASING CHANCES OF SNOW FRIDAY NIGHT INTO SATURDAY. FOR NOW WILL GO WITH RAIN/SNOW MIX ACROSS THE LOWER ELEVATIONS AND MORE SNOW ACROSS THE HIGHER TERRAIN. WILL INTRODUCE MENTION OF THIS SYSTEM INTO THE HWO. AT THIS EARLY JUNCTURE...THE MARGINAL BOUNDARY LAYER TEMPS SUGGEST THE BETTER CHANCE FOR ACCUMULATING SNOW WILL BE OVER THE HIGHER TERRAIN. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... STRATUS PUSHING SLOWLY NORTHWEST ACROSS THE REGION EARLY THIS MORNING. IFR CEILINGS HAD DEVELOPED AT KJHW FOR MUCH OF THE NIGHT BUT THE STRATUS HAS ERODED THERE. THE WESTERN EDGE OF THE STRATUS DECK SHOULD ERODED BEFORE REACHING AND TAF SITES. LIGHT FOG... GENERALLY 4-5 MILES WILL BURN OFF BY 13Z. THE REMAINDER OF THE DAY WILL SEE INCREASING MID AND UPPER LEVEL CLOUDINESS WORKING NORTHWARD AHEAD OF THE SOUTHEASTERN STATES LOW. MID LEVEL CEILINGS WILL LIKELY DEVELOP BY 00Z TONIGHT. VFR CONDITIONS ARE EXPECTED THROUGH THE END OF THE TAF PERIOD...ALTHOUGH CEILINGS WILL CONTINUE TO LOWER WITH THE CHANCE FOR THE WESTERN EDGE OF THE PRECIPITATION SHIELD ASSOCIATED WITH THE LOW PUSHING UP THE EASTERN SEABOARD REACHING EASTERN AND SOUTHERN AIRFIELDS BY 06Z. OUTLOOK... TUESDAY...MAINLY VFR. WEDNESDAY AND THURSDAY...VFR/MVFR WITH A CHANCE OF RAIN SHOWERS. FRIDAY...MVFR WITH A CHANCE OF RAIN/SNOW SHOWERS. && .MARINE... WINDS WILL REMAIN OUT OF THE EAST THROUGH MIDWEEK ON BOTH LAKES ERIE AND ONTARIO. THE EASTERLIES WILL INCREASE LATER TODAY AND THIS EVENING AND CREATE CHOPPY CONDITIONS ON LAKE ONTARIO. THE FORECAST EAST-SOUTHEAST WIND DIRECTION SHOULD KEEP THE LARGEST WAVE ACTION WELL OFFSHORE AND ALONG THE CANADIAN SHORELINE...SO NO SMALL CRAFT ADVISORIES WILL BE ISSUED AT THIS TIME. WINDS WILL DIMINISH LATER TONIGHT. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...HITCHCOCK NEAR TERM...TMA SHORT TERM...HITCHCOCK LONG TERM...HITCHCOCK AVIATION...TMA MARINE...HITCHCOCK