FXUS61 KBUF 270452
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1152 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 /06Z FRIDAY THROUGH TUESDAY/...
CIGS ACROSS THE REGION WILL DETERIORATE DURING THE COURSE OF THE 
NIGHT...WITH VFR/MVFR CIGS OF 2500-4000 FT LOWERING TO AROUND 1500 
FEET FOR MOST TAF SITES BY DAYBREAK. 

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 PARTS OF THE FINGER LAKES AND EASTERN LAKE ONTARIO REGIONS 
FOR MUCH OF THE REMAINDER OF THE OVERNIGHT...WITH VSBYS AND CIGS 
LOWERING TO AT LEAST MVFR LEVELS.

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. 

FOR FRIDAY...THE LOW CIGS WILL REMAIN IN PLACE ACROSS THE REGION. 
IFR TO MVFR CIGS OF 800-1500 FEET WILL BE FOUND REGIONWIDE DURING 
THE MORNING. ONLY MINIMAL IMPROVEMENT IS POSSIBLE FOR THE AFTERNOON.

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...RSH
MARINE...APFFEL/SFM