000
FXUS61 KBUF 240807
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
307 AM EST TUE NOV 24 2009

.SYNOPSIS...
HIGH PRESSURE WHICH PROVIDED THE FINE WEATHER TO OUR REGION TODAY 
WILL RETREAT INTO NEW ENGLAND TONIGHT AND ALLOW A SOUTHERLY FLOW OF 
MOIST AIR TO OVERSPREAD WESTERN AND CENTRAL NEW YORK LATER TONIGHT 
AND TUESDAY. THIS FLOW WILL RESULT IN PLENTY OF CLOUDINESS TUESDAY 
AND WEDNESDAY BUT ONLY A FEW SHOWERS AND IT WILL STAY QUITE MILD. LOW 
PRESSURE WILL DEEPEN OVER THE GREAT LAKES ON THURSDAY AND TRANSFER 
ITS ENERGY TO ANOTHER LOW ALONG THE EAST COAST FRIDAY AND SATURDAY 
RESULTING IN AN INCREASING THREAT OF RAIN AND WET SNOW FROM THURSDAY 
NIGHT THROUGH SATURDAY AS COLDER AIR GETS DRAWN INTO THE SYSTEM.

&&

.NEAR TERM /THROUGH TONIGHT/...
MOISTURE CHANNEL IMAGERY SHOWING A WEAK MID LEVEL SHORTWAVE LIFTING 
NORTHEAST ACROSS THE CWA EARLY THIS MORNING. RADAR IMAGERY SHOWS A 
FEW LIGHT SHOWERS ASSOCIATED WITH THIS FEATURE...ALTHOUGH MUCH OF 
THIS ACTIVITY IS TRACING OUT SO FAR. ONE AREA OF MORE CONCENTRATED 
SHOWER ACTIVITY EXTENDING FROM CENTRAL PA INTO THE CENTRAL SOUTHERN 
TIER WILL LIFT NORTH TOWARDS THE FINGER LAKES AND TEND TO WEAKEN 
THROUGH DAYBREAK AS IT MOVES INTO DRIER AIR.

SHORT TERM MODEL GUIDANCE IN GOOD AGREEMENT IN LIFTING THE MID LEVEL 
SHORTWAVE ACROSS THE AREA THIS MORNING AND DE-AMPLIFYING WITH TIME. 
THE MID LEVEL WAVE WILL REACH THE SAINT LAWRENCE VALLEY BY 18Z THEN 
QUICKLY EXIT INTO NORTHERN NEW ENGLAND THROUGH THE AFTERNOON. THE 
SHOWER CHANCES CAN BE DIVIDED INTO TWO SEPARATE FORCING MECHANISMS. 
THE FIRST IS ALIGNED WITH THE DPVA REGION AHEAD OF THE MID LEVEL 
SHORTWAVE. THIS WILL LIFT ACROSS LAKE ONTARIO AND REACH THE EASTERN 
LAKE ONTARIO REGION BY DAYBREAK. EXPECT THIS ACTIVITY TO WANE WITH 
NORTHEAST EXTENT AS THE SHORTWAVE WEAKENS AND THE SHOWERS MOVE INTO 
A DRIER AND DRIER LOW LEVEL AIRMASS. THE SECOND AREA OF FORCING IS 
ASSOCIATED WITH A PLUME OF SLIGHTLY HIGHER THETA-E CONTENT AIR NOTED 
WITH THE CONCENTRATED AREA OF SHOWERS IN CENTRAL PA. THIS TOO WILL 
WEAKEN WITH NORTHERN EXTENT...BUT SHOULD STILL BRING A FEW LIGHT 
SHOWERS THROUGH MIDDAY FROM THE INTERIOR SOUTHERN TIER THROUGH THE 
FINGER LAKES. EXPECT THIS ACTIVITY TO END BY EARLY AFTERNOON AS 
FORCING AND MOISTURE TRANSPORT BREAK DOWN IN RESPONSE TO INCREASING 
RIDGING ALOFT.

QPF WILL BE VERY LIGHT TODAY...WITH JUST A TRACE TO A FEW HUNDREDTHS 
IN MOST LOCATIONS. THE INTERIOR SOUTHERN TIER AND FINGER LAKES MAY 
GET A LITTLE MORE...BUT STILL LESS THAN A TENTH. OTHERWISE...EXPECT 
PLENTY OF CLOUD COVER TODAY AS LOW LEVEL MOISTURE BECOMES TRAPPED 
BENEATH A DEVELOPING SUBSIDENCE INVERSION. DESPITE THE CLOUDS... 
925MB TEMPS OF AROUND +6C WILL STILL SUPPORT LOW 50S ACROSS THE 
LOWER ELEVATIONS OF WESTERN NY...WITH UPPER 40S ACROSS THE HIGHER 
TERRAIN OF THE SOUTHERN TIER AND THE NORTH COUNTRY. 

TONIGHT ANY SHOWER ACTIVITY WILL BE LONG GONE...WITH THE MAIN 
FORECAST CHALLENGE EXTENT OF CLOUD COVER. EXPECT THE EVENING TO 
START OFF BKN-OVC EVERYWHERE WITH PLENTY OF STRATUS AROUND. 
OVERNIGHT INCREASING SOUTHEAST DOWNSLOPE WINDS MAY ERODE THE STRATUS 
ACROSS THE LOWER ELEVATIONS DUE TO DOWNSLOPING. THIS WOULD HAPPEN 
FIRST ALONG THE LAKE ERIE SHORE...THEN SPREAD ACROSS THE NIAGARA 
FRONTIER EAST TO THE ROCHESTER AREA OVERNIGHT. HAVE ATTEMPTED TO 
INDICATE THIS IN GRIDS/ZFP. ACROSS THE HIGHER TERRAIN...EXPECT 
STRATUS TO HANG TOUGH WITHOUT THE AID OF DOWNSLOPING. CLOUDS AND A 
DEVELOPING DOWNSLOPE WIND WILL HELP KEEP TEMPS UP OVERNIGHT WITH 
LOWS WELL ABOVE AVERAGE ONCE AGAIN.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
A WEAK RIDGE OF HIGH PRESSURE WILL DRIFT ACROSS THE EASTERN LAKES 
TUESDAY NIGHT WITH MAINLY DRY CONDITIONS...BUT LOW CLOUDINESS WILL 
HOLD TIGHT. TEMPS WILL REMAIN MILD. 

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 12Z 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 MONDAY/...
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. WILL CONTINUE 
WITH LOW CHANCE POPS FOR NOW...AND IT STILL APPEARS THAT THE COLDER AIR 
WILL HOLD OFF UNTIL FRIDAY...SO THE ABOVE AVERAGE TEMPERATURES WILL 
CONTINUE THROUGH THE HOLIDAY.

THINGS GET MUCH MORE INTERESTING THEREAFTER. 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 CYCLOGENESIS...WITH THE RESULTING SURFACE LOW LIFTING NORTH 
ACROSS NEW ENGLAND OR EASTERN NEW YORK LATE FRIDAY THROUGH SATURDAY. 
MODELS ARE FAIRLY CONSISTENT IN EVOLUTION AND MOVEMENT OF THESE 
FEATURES...BUT WITH SOME SUBTLE DIFFERENCES. ONE MAJOR ONE IS THE 
SHIFT WESTWARD IN ALL THE MODELS FROM YESTERDAY. THIS WOULD PLACE 
OUR ENTIRE AREA UNDER A DECENT PRECIP SHIELD FOR THURS NT AND FRI. 
BOTH THE GFS AND EC TAKE THE CENTER OF THE UPPER LOW WELL TO OUR 
SOUTH...ACROSS ERN OHIO AND PA TO NJ...WHICH WOULD PLACE OUR AREA 
UNDER AN EASTERLY FLOW OF MOISTURE SWINGING IN FROM THE 
ATLANTIC...WITH COLDER AIR (-6 TO -8C 850 MB) ASSOCIATED WITH THE 
UPPER LOW REMAINING WELL TO OUR SOUTH...WITH MILDER AIR WRAPPING IN 
FROM THE EAST (-1 TO -2C/850) ACROSS LK ONTARIO INTO MUCH OF OUR AREA. 
THIS WOULD IMPLY A MAINLY RAIN EVENT FOR LOW ELEVATIONS FURTHER 
NORTH AND A MIX OF WET SNOW THREAT ACROSS HIGHER ELEVS TOWARD THE PA 
LINE. POTENTIAL QPF COULD BE ON THE ORDER OF 0.5 TO 1 INCH. THE 
ECMWF IS A GOOD 6 TO 12 HOURS FASTER WITH ALL THIS...WITH BULK OF 
HEAVIEST QPF IN 00Z-12Z FRIDAY TIME PERIOD...RAIN EVENTUALLY ENDING 
AS WET SNOW OR A MIX...GFS WOULD BE LATER...RAIN LATER FRI INTO FRI 
NT AND MIXING AS IT ENDS LATE FRI NT/SAT AM. FOR NOW WILL GO WITH 
LIKELY POPS THURS NT THROUGH FRI NT. THIS COULD BE A CASE OF HEAVY 
SNOW IN PA/WVA AND RAIN IN MUCH OF NY STATE...BUT STAY TUNED.

SOMEWHAT COLDER AIR FOLLOWS IN WRAPAROUND ON SAT...WILL GO WITH CHC 
POPS ALL AREAS...LIKELY SE OF LAKES IN UPSLOPE. DRIER WX FOR SUNDAY 
AND MONDAY WITH MORE SEASBL TEMPS.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
DURING THE FORECAST PERIOD...A SHORTWAVE TROUGH OVER THE OHIO
VALLEY WILL CONTINUE TO WEAKEN AND LIFT NORTHEAST INTO NEW YORK
STATE OVERNIGHT...BEFORE PASSING OFF INTO NEW ENGLAND ON TUESDAY. IN
ADVANCE OF THIS FEATURE...A FEED OF ATLANTIC MOISTURE WILL
CONTINUE TO SPREAD ACROSS THE AREA OVERNIGHT...WITH MID AND HIGH
CLOUDS THICKENING AND LOWERING INTO THE HIGH MVFR/LOW VFR RANGE.

AS THE AFOREMENTIONED SHORTWAVE LIFTS NORTHEAST AND INTERACTS WITH
THIS FEED OF MOISTURE...IT WILL TOUCH OFF SOME SPRINKLES OR LIGHT
SHOWERS ACROSS THE SOUTHERN TIER AND PORTIONS OF THE NIAGARA
FRONTIER/FINGER LAKES THROUGH EARLY TUESDAY...HOWEVER THESE SHOULD BE
INSIGNIFICANT WITH LITTLE IF ANY IMPACT ON AVIATION. AS SUCH...HAVE
JUST CONTINUED WITH A MENTION OF VCSH TO COVER THIS POTENTIAL.

AFTER THE SHORTWAVE PASSES TO THE NORTHEAST ON TUESDAY...RIDGING
ALOFT WILL BECOME RE-ESTABLISHED ACROSS NEW YORK STATE. WITH THE
LOW LEVEL FLOW REMAINING RATHER WEAK...THIS WILL HELP TO TRAP LOW
LEVEL MOISTURE ACROSS THE AREA THROUGH THE END OF THE TAF PERIOD.
AS A RESULT...AVIATION INTERESTS CAN EXPECT MVFR CIGS TO LINGER
ACROSS THE AREA THROUGH TUESDAY EVENING.

OUTLOOK...
WEDNESDAY AND WEDNESDAY NIGHT...VFR/MVFR WITH A CHANCE
OF RAIN SHOWERS. 
THURSDAY AND THURSDAY NIGHT...VFR DETERIORATING TO MVFR/IFR WITH
INCREASING CHANCES OF RAIN. 
FRIDAY...MVFR/IFR WITH RAIN LIKELY...MIXING WITH SNOW ACROSS THE
SOUTHERN TIER. 
SATURDAY...MVFR WITH A CHANCE OF RAIN AND SNOW.

&&

.MARINE...
WINDS WILL REMAIN OUT OF THE EAST THROUGH MIDWEEK ON BOTH LAKES ERIE 
AND ONTARIO. THE EASTERLIES WILL INCREASE 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. THE NEXT 
THREAT FOR MARINE FLAGS WILL LIKELY BE ON FRIDAY AS A DEEPENING LOW 
PASSES UP TO OUR EAST.

&&

.CLIMATE...
STILL NO MEASURABLE SNOW SO FAR THIS SEASON OVER MOST OF WESTERN NY. 
WE ARE ALREADY OVER TWO WEEKS LATE (NORMAL DATES ARE NOV 7 BUF AND 
NOV 8 ROC). WE WILL AT LEAST GET TO FRIDAY (27TH) AND IF SO...WILL 
BE LATEST IN 61 YRS (1948) AT BUF...AND LATEST IN 46 YRS (1963) AT 
ROC. THE ALL TIME RECORD LATEST DATES FOR FIRST MEASURABLE SNOW ARE 
DEC 3 1899 AT BUF AND DEC 10 1948 AT ROC. WE WILL NOT LIKELY REACH 
THOSE DATES AS WX PATTERN LOOKS COLDER WITH SOME SNOW THREAT 
BEGINNING LATER FRIDAY. 

IN ADDITION, ITS BEEN A LONG TIME SINCE EITHER BUFFALO OR
ROCHESTER LAST SAW MEASURABLE SNOW. THROUGH TODAY, BUFFALO HAS
GONE 229 DAYS WITHOUT MEASURABLE SNOW, OR SINCE APRIL 7, 2009.
THIS IS THE 6TH LONGEST STRETCH IN 125 YEARS OF RECORDS. THE
RECORD IS 245 DAYS SET BACK IN 1948. ROCHESTER IS ALSO AT 229 DAYS
WITHOUT MEASURABLE SNOW, OR THE 7TH LONGEST STRETCH THERE. THE
RECORD IS 260 DAYS SET BACK IN 1952. IF WE REMAIN SNOW FREE
THROUGH THANKSGIVING, BOTH ROCHESTER AND BUFFALO WILL END UP WITH
THE THIRD LONGEST STRETCH OF SNOW FREE DAYS ON RECORD. STAY TUNED.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...SFM
NEAR TERM...HITCHCOCK
SHORT TERM...SFM
LONG TERM...HITCHCOCK/SFM
AVIATION...JJR
MARINE...SFM/WCH
CLIMATE...SFM