Area Forecast Discussion
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000
FXUS61 KBUF 240335
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1035 PM EST MON NOV 23 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 TUESDAY/...
UPDATE AS OF 1030 PM...REGIONAL SATELLITE DISPLAYS SHOW A MID-
LEVEL SHORTWAVE TROUGH SLIDING NORTHEAST ACROSS OHIO AND WESTERN
PA...WITH BOTH THIS SHORTWAVE AND AN INFLUX OF ATLANTIC MOISTURE
LEADING TO A GRADUAL SOUTHWEST TO NORTHEAST INCREASE IN CLOUD
COVER ACROSS THE FORECAST AREA. AS THIS SHORTWAVE INTERACTS WITH
THIS MOISTURE...IT IS ALSO GENERATING A FAIRLY NARROW SWATH OF
SHOWERS ACROSS EASTERN LAKE ERIE AND THE SOUTHERN TIER...WITH
UPSTREAM SURFACE OBS OVER NW PA INDICATING THAT THE BULK OF THIS
ACTVITY HAS BEEN RATHER LIGHT AS IT PUSHES INTO THE RATHER DRY
AIRMASS ACROSS NEW YORK STATE...WITH ONLY A FEW HUNDREDTHS OF AN
INCH REPORTED HERE AND THERE.

BASED ON RECENT SATELLITE AND RADAR TRENDS WHICH SHOW THE PRECIP
LIFTING NORTHEAST CONSIDERABLY FASTER THAN EARLIER INDICATED...HAVE
UPDATED THE FORECAST TO INCREASE THE FORWARD PROGRESS OF THE
SHOWERS OVERNIGHT...NOW BRINGING THESE INTO THE NIAGARA FRONTIER
AND MIDDLE/LOWER GENESEE VALLEYS AFTER MIDNIGHT. HAVE ALSO UPPED
POPS A BIT FROM CONTINUITY BASED ON RADAR RETURNS...THOUGH HAVE
KEPT THESE CONFINED TO THE CHANCE RANGE OWING TO THE RATHER LIGHT
NATURE OF THE PRECIP SO FAR...AND THE FACT THAT THIS SHOULD TEND
TO WEAKEN AS IT LIFTS FURTHER NORTH INTO OUR RATHER DRY AIRMASS.

HAVE ALSO UPPED OVERNIGHT LOWS SOME 2-3 DEGREES IN MOST AREAS
BASED ON CURRENTLY WARMER THAN FORECAST SURFACE OBSERVATIONS AND
THE ADVANCING CLOUD COVER...WHICH SHOULD HELP TO HOLD READINGS UP
A BIT MORE FOR AREAS OUTSIDE OF THE NORTH COUNTRY. THE EARLY
AFTERNOON NEAR TERM DISCO FOLLOWS BELOW...

A NARROW BAND OF SUNNY SKIES ARE THE REFLECTION OF A BLOCKING RIDGE
OF HIGH PRESSURE OVER WESTERN AND NORTHERN NY THIS AFTERNOON. MID
CLOUDS WILL SPREAD IN FROM THE SOUTH THIS EVENING AS A SHORT WAVE
RIDES THROUGH THE RIDGE. WHEREAS THE BETTER CHANCE OF RAIN WILL BE
FROM THE MID ATLANTIC TO THE NEW ENGLAND COASTS...THERE WILL BE
SCATTERED SPRINKLES AND LIGHT SHOWERS OVER WESTERN AND CENTRAL NY AS
THE SHORT WAVE MOVES THROUGH TONIGHT...THEN FADES DURING TUESDAY AS
UPPER RIDGING RETURNS. WILL HAVE 30 TO 40 POPS FROM ABOUT ROUTE 20A
SOUTHWARD AND INTO CENTRAL NY TO OSWEGO AND SOUTHERN LEWIS
COUNTIES...WITH A SHARP CUTOFF NORTHWARD EXCLUDING THE COUNTIES
ALONG MUCH OF THE SOUTH SHORE OF LAKE ONTARIO...AND ALSO EXCLUDING
MOST OF JEFFERSON COUNTY. NAM12 QPF OFFERS ONLY A FEW HUNDREDTHS FOR
THE TOTAL RAINFALL THROUGH MID MORNING ON TUESDAY.

LOW TEMPS TONIGHT HOLD UPPER 30S TO LOW 40S WITH THE BLANKET OF
CLOUDS...WITH SOME SPOTS AT FREEZING ACROSS THE NORTH COUNTRY WHERE
THE CLOUDS WILL BE LATER TO COVER THE AREA. HIGHS ON TUESDAY WILL
REACH THE UPPER 40S TO LOWER 50S ACROSS THE FORECAST AREA...THE
COOLER TEMPS IN THE NORTH COUNTRY WHERE THICKER CLOUDS WILL LINGER
THROUGH THE DAY.

&&

.SHORT TERM /TUESDAY NIGHT 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 /03Z 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 TONIGHT...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 TONIGHT...WITH MID AND HIGH CLOUDS
THICKENING AND LOWERING INTO THE LOWER END OF THE VFR RANGE ACROSS
THE BULK OF THE AREA. ACROSS THE WESTERN SOUTHERN TIER...ALREADY-
ESTABLISHED MVFR CEILINGS WILL LINGER THROUGH THE NIGHT...WITH THE
KBUF-KIAG CORRIDOR POSSIBLY ALSO SEEING A DETERIORATION TO MVFR
LATER ON IN THE NIGHT.

AS THE AFOREMENTIONED SHORTWAVE LIFTS NORTHEAST AND INTERACTS WITH
THIS FEED OF MOISTURE...IT MAY TOUCH OFF SOME SPRINKLES OR LIGHT
SHOWERS ACROSS THE SOUTHERN TIER AND PORTIONS OF THE NIAGARA
FRONTIER/FINGER LAKES TONIGHT AND EARLY TUESDAY...HOWEVER THESE
SHOULD BE INSIGNIFICANT WITH LITTLE IF ANY IMPACT ON AVIATION. AS
SUCH...HAVE JUST CONTINUED WITH A MENTION OF VCSH AT THE
WESTERNMOST TAF SITES 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 TO LOW- END VFR
CIGS TO LINGER ACROSS THE AREA THROUGH TUESDAY.

OUTLOOK...
TUESDAY NIGHT...MAINLY VFR.
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...JJR/WCH
SHORT TERM...SFM
LONG TERM...HITCHCOCK/SFM
AVIATION...JJR
MARINE...SFM/WCH
CLIMATE...SFM







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