FXUS61 KBUF 270020
AFDBUF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
720 PM EST THU NOV 26 2009
.SYNOPSIS...
LOW PRESSURE WILL DEVELOP OFF THE NEW ENGLAND COAST TONIGHT AND
DEEPEN AS IT MOVES TO THE CANADIAN MARITIMES FRIDAY. ONLY LIGHT
RAIN IS EXPECTED ACROSS OUR AREA WITH SOME WET SNOW AT HIGHER
ELEVATIONS. DRIER AIR WILL RETURN FOR SATURDAY AND MUCH OF
SUNDAY...BUT ANOTHER LOW WILL MOVE FROM THE OHIO VALLEY TO THE MID
ATLANTIC COAST AND SPREAD SOME RAIN INTO OUR AREA LATER SUNDAY AND
SUNDAY NIGHT...PERHAPS ENDING AS A BIT OF WET SNOW MONDAY.
&&
.NEAR TERM /THROUGH FRIDAY/...
AN UPPER LEVEL LOW ACROSS THE EASTERN LAKES WILL SLOWLY MOVE EAST AS
DEVELOPING LOW PRESSURE MOVES UP THE EASTERN SEABOARD. THE LOW WILL
RAPIDLY INTENSIFY NEAR MAINE ON FRIDAY...BUT BEFORE THAT AN INVERTED
TROF WILL SET UP BETWEEN THE DEVELOPING LOW AND THE 500 MB LOW. THIS
AXIS WAS FAIRLY UNEVENTFUL THIS MORNING...AS THERE WAS LIMITED
MOISTURE...HOWEVER AN EASTERLY FLOW FROM 925 MB - 850 MB WILL FEED
MOISTURE INTO THE TROUGH TONIGHT. THE 12Z GFS WAS SIGNIFICANTLY
FASTER THAN THE NAM IN HOW QUICKLY THIS MOISTURE REACHED THE
AREA...HOWEVER RAIN SHOWERS DEVELOPING IN CENTRAL PENNSYLVANIA IS
SUPPORTING THE FASTER GFS SOLUTION. EXPECT THE AXIS TO SLOWLY MOVE
EASTWARD THROUGH THIS EVENING...WITH PRECIPITATION GRADUALLY FILLING
IN FROM THE SCATTERED ACTIVITY CURRENTLY IN PLACE...TO A SOLID BAND
OF PRECIPITATION. BY MIDNIGHT...THE AXIS SHOULD BE ROUGHLY ACROSS
OSWEGO...GRADUALLY PIVOTING AS IT MOVES EAST THROUGH FRIDAY MORNING.
DYNAMICALLY...IT WILL COOL ALOFT AS IT WARMS IN THE LOW-MID LAYERS
TONIGHT...THEN EVENTUALLY COLDER AIR WILL SNEAK IN AT THE
SURFACE...RESULTING IN A FAIRLY COMPLEX FORECAST SOUNDING. THE
PRIMARY CAUSE OF PRECIPITATION WILL BE THE LOW-MID WARM AIR
ADVECTION...AND THE CONDITIONALLY UNSTABLE SOUNDING ABOVE
IT...SUPPORTING A NAM/GFS BLEND OF .50 TO 1.00 OF QPF FROM OSWEGO
EASTWARD. QPFS WILL CUT OFF DRAMATICALLY TO THE WEST...AS THE UPPER
TROF AXIS KEEPS A WESTERLY FLOW IN THE LOW-MID LEVELS...PREVENTING
LIFT HERE...BUT ENHANCING IT JUST EAST. THERE WILL BE A SECONDARY
AREA OF PRECIPITATION WHICH DEVELOPS TONIGHT...RESULTING FROM LAKE
ERIE. MODEST DELTA T/S WILL COMBINE WITH SOME OROGRAPHIC LIFTING ON
THE CHAUTAUQUA RIDGE...WITH SOME PRECIPITATION DEVELOPING. DURING
THE EARLY MORNING HOURS...MAY SEE A SHOWER SNEAK INTO BUFFALO AND
VICINITY...THOUGH THIS WILL END QUICKLY AFTER SUNRISE AS THE
NORTHWEST FLOW KICKS IN.
ALL OF THIS WILL RESULT IN TWO AREAS OF CATEGORICAL POPS...THE
WESTERN HALF OF THE CWA...AND THE SOUTHERN TIER...WITH ELSEWHERE
GENERALLY FALLING IN THE CHANCE RANGE. PRECIPITATION TYPE WILL
INITIALLY NOT BE AN ISSUE TONIGHT...WITH 850 MB TEMPERATURES
STARTING NEAR 0 C WEST...AND WARMER EAST. HOWEVER...COLDER AIR WILL
BUILD IN WITH THE SYSTEM...WITH WHAT PRECIPITATION DOES
DEVELOP...MIXING WITH AND CHANGING TO SNOW ACROSS HIGHER TERRAIN IN
THE SOUTHERN TIER LATE TONIGHT. THE LAKE SHOULD BE TOO WARM FOR
LOCATIONS NEAR LAKE ERIE TO SEE ACCUMULATING SNOW...BUT OVER 1000
FT...EXPECT TO SEE 1 TO 3 INCHES OF WET SNOW...MAINLY FALLING LATE
TONIGHT AND FRIDAY MORNING. TEMPERATURES ALOFT WILL BE SLOWER TO
WARM IN EASTERN PORTIONS...FORTUNATE...CONSIDERING THE GREATER QPFS
THERE. HOWEVER...BY DAYBREAK...EXPECT TO SEE THE HIGHER TERRAIN ON
THE TUG HILL PLATEAU TO START TO MIX WITH SNOW...WITH ELEVATIONS
OVER 1000 FEE THERE SEEING SOME MIXING...AND PERHAPS AN INCH OR TWO
OF WET SNOW.
LEAN A BIT TOWARDS THE GFS...EXPECTING PRECIPITATION TO TAPER OFF
DURING THE MORNING HOURS IN THE NORTH COUNTRY AS THE LOW
INTENSIFIES...GETTING CAPTURED BY THE 500 MB TROF AND ENDING THE
INVERTED TROF. HOWEVER...MAY SEE SOME SHOWERS WRAP AROUND THE LOW
AND WILL CARRY AT LEAST A CHANCE FOR THIS. TEMPERATURES LARGELY WARM
ENOUGH FOR RAIN AT THIS POINT...OUTSIDE OF HIGHER TERRAIN WHERE A
MIX IS STILL POSSIBLE. WINDS WILL BE FAIRLY BRISK WITH THE INTENSE
LOW...ESPECIALLY IN THE NORTH COUNTRY.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
THIS PERIOD WILL BEGIN WITH SOME WRAPAROUND PRECIP AS DEEPENING
MOVES ALONG THE MAINE COAST. BULK OF PRECIP WILL BE EAST OF OUR
AREA...BUT FLOW WILL LINE UP NORTHWESTERLY WHICH WILL BE
PERPENDICULAR TO THE HILLS OF THE SOUTHERN TIER...SO UPSLOPE PRECIP
WILL LINGER. THERE WOULD NORMALLY BE SOME LAKE ENHANCEMENT TOO...BUT
WITH BRISK NW WINDS...RESIDENCE TIME WILL BE BRIEF SO ANY PRECIP
WILL BE JUST UPSLOPE RELATED. TEMPS JUST DONT GET VERY COLD...IN -5C
RANGE AT 850 MB AND SNOW GROWTH PARAMETERS NOT GOOD...SO DO NOT
EXPECT MORE THAN AN INCH OR SO ALONG CHAUT RIDGE...MAYBE INCH OR TWO
ON TUG HILL CLOSER TO EXITING STORM. NO ISSUES ELSEWHERE.
SATURDAY WILL SEE IMPROVING CONDITIONS AS STORM PULLS AWAY INTO THE
MARITIMES. THERE MAY BE A BIT OF RESIDUAL PRECIP IN UPSLOPE AREAS
BUT MINIMAL. WILL GRADUALLY LOWER POPS THOSE AREAS DURING DAY AS
FLOW RELAXES AND BACKS...WITH JUST SOME CHC POPS SE OF LK ONTARIO
SAT EVE. 850 MB TEMPS WILL STILL BE IN -4 TO -6C RANGE MOST OF
DAY...SO TEMPS WILL STRUGGLE TO 40...BUT ACTUALLY NORMAL FOR END OF
NOVEMBER.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
MODELS FASTER IN SLIDING A COLD FRONT SOUTH AND EAST ACROSS THE
LOWER LAKES...NOW EXPECTED SUN NT AND EARLY MONDAY. GFS AND ECMWF
ALSO SHOW SOME MOISTURE STREAKING EASTWARD INTO OUR AREA SUNDAY
AFTERNOON AHEAD OF THIS FEATURE...SO WILL CONTINUE WITH CHC POPS THEN.
MODELS DIVERGE A BIT ON MONDAY WITH NAM AND GFS TAKING FRONT SOUTH
INTO PA WHILE RUNNING A WAVE OF LOW PRESSURE ALONG IT...BUT MOST OF
THE PRECIP WOULD BE OVER BEFORE ENOUGH COLD AIR WORKS IN TO CHANGE
IT TO SNOW OVER OUR AREA...BUT 12Z ECMWF IS ABOUT 6 HOURS SLOWER
WITH THE FRONT AND ASSOCIATED WAVE...AND GIVES US 0.25 TO 0.5 INCH
OF QPF MONDAY...WITH 850'S FALLING FROM -2C AT 12Z TO -6C AT 00Z
TUE. THIS WOULD RESULT IN A RAIN CHANGING TO WET SNOW SCENARIO WITH
SOME MINOR ACCUMS POSSIBLE. FOR NOW WILL TAPER POPS DOWN FROM NORTH
TO SOUTH AND MENTION JUST A MIX AT END...BUT THIS SUBJECT TO CHANGE.
A BRIEF SHOT OF COLDER AIR (-8C OR SO AT 850 MB) FOLLOWS TUES BUT
FLOW LOOKS WEAK NW THEN FLAT AS A RIDGE MOVES ACROSS...SO SO ONLY
LOW CHC POPS FOR SNOW SHOWERS SE OF THE LKS MON NT AND TUES AM. DRY
WX TUES PM AND WED AS SFC RIDGE PASSES BY. THURSDAY UNCERTAIN AS
MODELS HAVING A DIFFICULT TIME WITH UPPER LOW OVER SOUTHWEST AND
SPLIT FLOW...WITH SOUTHERN STREAM SENDING A STORM UP THE ATLANTIC
COAST...WHILE NORTHERN STREAM BEGINS TO DRAG ARCTIC AIR BEHIND A
DEVELOPING UPPER LOW OVER NORTHERN LAKES. WILL CARRY CHC POPS FOR
SHOWERS THURS AT THIS STAGE.
AND...FURTHER OUT...BOTH GFS AND ECMWF SHOW WESTERLY FLOW OF
INCREASINGLY COLDER AIR AROUND STRONG VORTEX OVER UPPER LAKES FROM
LATE THURS INTO THE FOLLOWING WEEKEND. SUCH A PATTERN WOULD SERVE TO
TURN ON THE LONG OVERDUE LAKE EFFECT MACHINE FOR US. STAY TUNED.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
WHILE VFR CONDITIONS WILL BE FOUND ACROSS THE VAST MAJORITY OF THE
REGION EARLY TONIGHT...CONDITIONS WILL DEFINITELY DETERIORATE AS THE
NIGHT PROGRESSES.
STATIONARY LOW PRESSURE NEAR LAKE HURON AND GEORGIAN BAY WILL
COMBINE WITH DEEPENING LOW PRESSURE OFF THE EAST COAST TO CIRCULATE
COPIOUS AMOUNTS OF LOW LEVEL MOISTURE ACROSS OUR REGION. A DEEP
SOUTHERLY FLOW OF THIS MOISTURE RICH AIR WILL RESULT IN WIDESPREAD
RAIN OVER THE FINGER LAKES AND EASTERN LAKE ONTARIO REGIONS FOR MUCH
OF THE OVERNIGHT...BUT VSBYS AND CIGS WILL REMAIN CLOSE TO OR JUST
BELOW VFR LEVELS.
CONDITIONS WILL DETERIORATE DURING THE EARLY MORNING (PRE DAWN )
HOURS WHEN CIGS WILL LOWER TO 1500 FT OR LESS FROM WEST TO EAST.
THESE LOW CIGS WILL THEN HANG ON THROUGH MUCH OF THE DAY FRIDAY...
WITH IFR TO MVFR CONDITIONS REGIONWIDE.
THE LOW CLOUDS WILL PRODUCE SOME MIXED RAIN AND WET SNOW SHOWERS
LATE TONIGHT AND EARLY FRIDAY MORNING...MAINLY SOUTH OF BUFFALO AND
ROCHESTER WHERE THE HIGHER SPOTS COULD EXPERIENCE IFR VSBYS REDUCED
IN JUST WET SNOW.
OUTLOOK...
FRIDAY NIGHT...LARGELY MVFR IN CIGS...WITH A CHANCE OF RAIN OR SNOW
SHOWERS.
SATURDAY...MAINLY VFR WITH PATCHY MVFR IN CIGS AND RAIN SHOWERS.
SUNDAY...VFR LIKELY...POSSIBLY MVFR IN SHOWERS.
MONDAY...MVFR IN RAIN/WET SNOW...IMPROVING TO VFR.
TUESDAY...VFR.
&&
.MARINE...
SMALL CRAFT ADVISORIES WILL BE NEEDED LATER FRIDAY AND SATURDAY.
MODERATE SOUTHWEST WINDS ON THE LAKE ERIE NEARSHORES WILL LIGHTEN
THIS EVENING AND BACK A BIT. WINDS WILL BE FAIRLY LIGHT TONIGHT
AND EARLY FRIDAY OVER LAKE ONTARIO AS AN UPPER LEVEL LOW MOVES
ACROSS THE EASTERN LAKES...WHICH EVENTUALLY LEADS TO DEVELOPMENT
OF A STORM ALONG THE NEW ENGLAND COAST ON FRIDAY WHICH WILL
RAPIDLY DEEPEN AS IT MOVES TO MAINE FRIDAY NIGHT AND THE CANADIAN
MARITIMES SATURDAY. NORTHWEST WINDS WILL INCREASE RAPIDLY FRIDAY
AFTERNOON AND BECOME BRISK TO STRONG FRIDAY NIGHT INTO SATURDAY
BEFORE DIMINISHING LATER SATURDAY AND SATURDAY NIGHT. WAVES WILL
BUILD TO OVER 4 FEET LATER FRIDAY AFTERNOON...ESPECIALLY ON LAKE
ONTARIO. SMALL CRAFT ADVISORIES WILL BE NECESSARY FRIDAY AFTERNOON
THROUGH ALL OF SATURDAY AND INTO SATURDAY NIGHT. WILL NOT ISSUE
FLAGS QUITE YET BUT THEY WILL BE IN LATER SHIFTS.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SFM
NEAR TERM...APFFEL
SHORT TERM...SFM
LONG TERM...SAGE/SFM
AVIATION...APFFEL/RSH
MARINE...APFFEL/SFM
