FXUS61 KBUF 270000
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
700 PM EST SAT DEC 26 2009

.SYNOPSIS...
LOW PRESSURE NEAR CHICAGO WILL TRACK NORTHEAST TONIGHT AND SUNDAY... 
EVENTUALLY REACHING JAMES BAY BY SUNDAY EVENING. OCCASIONAL RAIN 
SHOWERS IN ADVANCE OF THIS LOW WILL GRADUALLY TAPER OFF TO SCATTERED 
RAIN AND SNOW SHOWERS TONIGHT. A FEW MORE SNOW SHOWERS WILL THEN BE 
POSSIBLE ON SUNDAY...THEN AN ARCTIC COLD FRONT WILL BRING A BETTER 
CHANCE ON SNOW ON MONDAY...WITH MUCH COLDER TEMPERATURES FOLLOWING 
IN ITS WAKE FOR MONDAY NIGHT AND TUESDAY.

&&

.NEAR TERM /THROUGH SUNDAY/...
630 PM UPDATE...BACK EDGE OF STEADY PRECIP CONTINUES TO PULL VERY
VERY SLOWLY EASTWARD...CURRENTLY ALONG ERIE/GEN/WYO COUNTY
LINE...AND AT THE CURRENT RATE SHOULD END OVER ROCH AND GEN VALLEY
BY 10 PM OR SO...AS A STRIP OF WET SNOW. SOME SHARP CLEARING
MOVING INTO BUF AREA ATTM...WITH SKC ALL ACROSS SW NY INTO ERN
OHIO. CURRENT SKY AND POP GRIDS REFLECT THIS THINKING VERY
WELL...SO WILL MAKE ONLY SOME VERY MINOR TWEAKS TO THESE
GRIDS...WILL HAVE TO KEEP AN EYE ON ANY FOG FORMATION WITH THE LGT
WINDS BUT WILL HOLD OFF FOR NOW. NO OTHER CHANGES AT THIS
TIME...BUT WILL REVISIT ALL BEFORE 10 PM. PREV DISC FOLLOWS...

MOISTURE CHANNEL IMAGERY VERY IMPRESSIVE THIS EVENING WITH A HUGE
MID LEVEL CLOSED LOW CENTERED OVER SOUTHERN WISCONSIN...WITH A
CIRCULATION FOOTPRINT COVERING 2/3 OF THE CONUS. AHEAD OF THIS
SYSTEM...THE SUB-TROPICAL BRANCH OF THE JET STREAM HAS BEEN
CAPTURED AND EXTENDS FROM CENTRAL MEXICO ALL THE WAY UP THE
EASTERN SEABOARD TO NEW ENGLAND...WITH A TROWAL AIRSTREAM WRAPPING
BACK INTO THE CYCLONE. THE MID LEVEL LOW HAS STALLED ITS EASTERN
PROGRESS THIS AFTERNOON...AND THAT COMBINED WITH A WEAK WAVE OF
LOW PRESSURE ALONG THE MID ATLANTIC COAST HAS BROUGHT THE EASTWARD
PROGRESS OF A COLD OCCLUSION TO A HALT...WITH THE FRONT SITTING IN
WESTERN NY AT 23Z. THE FRONT HAS TAKEN ON ANABATIC
CHARACTERISTICS...WITH THE COLD AIR CUTTING UNDER MOISTURE ALOFT.

STRONG 900-600MB STRETCHING DEFORMATION ALONG THE WESTERN EDGE OF A 
70+ KNOT LOW LEVEL JET SITUATED OVER EASTERN NEW YORK WILL CONTINUE 
TO PRODUCE WIDESPREAD LIGHT TO BRIEFLY MODERATE PRECIP ACROSS 
WEST CENTRAL NEW YORK THROUGH MUCH OF THE EVENING...ENDING ONLY
SLOWLY FROM WEST TO EAST TONIGHT. THERE WILL BE A BRIEF
CHANGEOVER TO WET SNOW NEAR THE END...BUT EXPECT LITTLE OR NO
ACCUMULATION. ONE EXCEPTION MAY BE THE TUG HILL LATE TONIGHT
WHERE A SLUSHY COATING TO AN INCH MAY ACCUMULATE.

OVERNIGHT A DRY SLOT...EVIDENT IN VISIBLE SATELLITE IMAGERY JUST 
UPSTREAM OVER OHIO AND WESTERN PA WILL CONTINUE TO WORK EAST
ACROSS THE AREA. THIS WILL BRING A PERIOD OF PARTLY CLOUDY OR EVEN
MAINLY CLEAR SKIES FOLLOWING THE END OF PRECIP.

LATE TONIGHT AND SUNDAY WRAP AROUND MOISTURE AND COLDER AIR WILL 
GRADUALLY FILTER INTO THE AREA. EXPECT CLOUDS TO INCREASE AGAIN FROM 
WEST TO EAST AS THE DEEPER MOISTURE ARRIVES. MID LEVEL HEIGHT FALLS 
WILL OVERSPREAD WESTERN NY DURING THE AFTERNOON WITH ASSOCIATED DPVA 
BRINGING AN INCREASE IN LARGE SCALE FORCING FOR ASCENT. THIS WILL 
ALLOW SCATTERED SNOW SHOWERS TO DEVELOP ACROSS WESTERN NY DURING THE 
AFTERNOON. AMOUNTS SHOULD BE LIGHT WITH JUST A COATING IN MOST 
PLACES. SOME LIMITED LAKE ENHANCEMENT MAY GET GOING DURING THE 
AFTERNOON TO THE NORTHEAST OF LAKE ERIE. 850MB TEMPS FALL TO ABOUT 
-10C BY 00Z MONDAY...SUPPORTING LAKE INDUCED CAPES OF AROUND 150J/KG 
AND EQUILIBRIUM LEVELS OF 5-6K FEET. THERMODYNAMICS WILL BE VERY 
MARGINAL...BUT INCREASING LARGE SCALE SUPPORT WILL PROBABLY ALLOW 
SOME LIMITED LAKE ENHANCEMENT ACROSS THE NIAGARA FRONTIER FROM THE 
BUF METRO AREA NORTHWARD INTO SOUTHERN NIAGARA AND ORLEANS COUNTIES. 
EXPECT ANY ACCUMULATION TO BE VERY LIMITED THROUGH 00Z MONDAY WITH 
SURFACE TEMPS REMAINING A LITTLE ABOVE FREEZING. WILL JUST INDICATE 
AN AREA OF HIGHER POPS WITH AN INCH OR LESS ACROSS THE NIAGARA 
FRONTIER FOR THE AFTERNOON.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
DURING SUNDAY NIGHT...A GENERAL LIKELIHOOD OF SNOW SHOWERS IS 
EXPECTED ACROSS THE AREA AS THE MAIN UPPER LEVEL LOW CENTER TRACKS  
EAST ACROSS NEW YORK STATE...WITH A GENERAL INCH OR SO OF SNOW 
POSSIBLE IN MOST LOCATIONS. THE SNOW SHOWERS WILL ALSO BE ENHANCED 
A BIT DOWNWIND OF LAKES ERIE AND ONTARIO...WITH THE AREAS OF 
ENHANCED SNOWFALL TENDING TO DRIFT SOUTHWARD WITH TIME AS THE 
STEERING WINDS VEER FROM SOUTHWEST TO WEST. THE ABOVE SAID...IT 
STILL APPEARS THAT THE LAKE ENHANCEMENT WILL BE HELD IN CHECK BY THE 
COMBINATION OF MARGINALLY COLD ENOUGH TEMPERATURES ALOFT AND THE 
CLOSE PROXIMITY OF THE UPPER LEVEL LOW...WHICH WILL RESULT IN A FAIR 
AMOUNT OF SHEAR THROUGH A DEEP LAYER. ACCORDINGLY...EXPECT SNOWFALL 
AMOUNTS WITHIN THE AREAS OF LAKE ENHANCED SNOW TO BE ON THE ORDER OF 
1-3"...OR BELOW ADVISORY CRITERIA. 

THEN ON MONDAY...A POLAR VORTEX DROPPING SOUTH FROM HUDSON BAY WILL 
REINFORCE THE UPPER LEVEL TROUGH THAT WILL BE IN PLACE OVER THE 
LOWER GREAT LAKES AND NEW ENGLAND...WITH AN ASSOCIATED ARCTIC FRONT 
CROSSING THE AREA LATER MONDAY AFTERNOON. A GENERAL BURST OF SNOW 
SHOWERS IS EXPECTED TO ACCOMPANY THE FRONTAL PASSAGE...WHICH WILL 
CONTINUE TO BE COVERED EVERYWHERE WITH LIKELY POPS...AND THE 
POTENTLY FOR ANOTHER INCH OR SO OF ACCUMULATION IN THE GRIDS. AREAS 
OF LAKE ENHANCEMENT WILL ALSO CONTINUE DURING THE DAY OFF BOTH 
LAKES...THOUGH WITH A FAIR AMOUNT OF SHEAR AND MARGINALLY-COLD 
TEMPERATURES CONTINUING ALOFT...THIS WILL LIKELY BE HELD IN CHECK 
ONCE AGAIN. GIVEN THE AMOUNT OF SHEAR EXPECTED AND CONTINUING MODEL  
DIFFERENCES WITH RESPECT TO THE EXACT ORIENTATION OF THE STEERING 
WINDS...WHICH VARY FROM WEST-SOUTHWESTERLY TO WESTERLY...WILL 
CONTINUE TO PAINT A RATHER LARGE AND BROAD AREA OF LAKE ENHANCEMENT 
EAST OF BOTH LAKES DURING THE DAY...WHERE ANOTHER 1-3" OF SNOW WILL 
BE POSSIBLE. 

FOLLOWING THE PASSAGE OF THE SURFACE FRONT MONDAY EVENING...WINDS
WILL VEER SHARPLY TO THE NORTHWEST AND ALLOW MUCH COLDER AIR TO
FLOOD ACROSS THE REGION...WITH 850 MB TEMPS PLUMMETING TO THE -20C
TO -24C RANGE BY TUESDAY MORNING...AND 925 MB READINGS FALLING TO
-14C TO -22C. THIS WILL RESULT IN TEMPERATURES TURNING SHARPLY
COLDER ACROSS THE REGION AS THE NIGHT PROGRESSES...WITH ANY LAKE
SNOWS SHIFTING SOUTHWARD TO AREAS SOUTHEAST OF THE LAKES AND
BECOMING MORE MULTIBANDED IN NATURE. WILL KEEP LIKELY POPS IN PLAY
FOR THE EXPECTED LAKE EFFECT AREAS DURING THIS PERIOD...WITH JUST
A GENERAL CHANCE OF SNOW SHOWERS ELSEWHERE GIVEN THE COLD
NORTHWESTERLY FLOW ACROSS THE LAKES. GIVEN THE EXTENT OF THE COLD
ADVECTION EXPECTED MONDAY NIGHT...HAVE LOWERED TEMPERATURES
SEVERAL CATEGORIES FROM EXISTING CONTINUITY...WITH MOST AREAS NOW
FALLING TO WITHIN A FEW DEGREES OF 10F BY MORNING...AND READINGS
DIPPING CLOSER TO ZERO ACROSS THE NORTH COUNTRY.

ON TUESDAY...THE LAKE EFFECT SNOWS ARE EXPECTED TO CONTINUE 
SOUTHEAST OF THE LAKES AS A WELL-ALIGNED COLD NORTHWEST FLOW REMAINS 
INTACT ACROSS THE AREA...ALONG WITH SUFFICIENT LOW LEVEL MOISTURE 
AND A DECENT SNOW GROWTH AREA BELOW A CAPPING INVERSION SITUATED 
AROUND 5 KFT. ACCORDINGLY...WILL KEEP LIKELY POPS IN PLAY IN THESE 
AREAS DURING THIS PERIOD...WITH JUST A GENERAL CHANCE OF SNOW 
SHOWERS FOUND ELSEWHERE. WITH 925 MB TEMPS GENERALLY RANGING FROM 
-13C ACROSS FAR SOUTHWESTERN NY TO -22C ACROSS THE NORTH 
COUNTRY...MOST AREAS WILL SEE HIGHS ONLY IN THE MID TO UPPER TEENS 
ON TUESDAY...WITH READINGS LIKELY TO REMAIN LOCKED IN THE SINGLE 
DIGITS ACROSS THE NORTH COUNTRY. 

DURING TUESDAY NIGHT...THE LAKE SNOWS WILL SLOWLY DIMINISH AS WARM 
ADVECTION DEVELOPS ALOFT...THE CAPPING INVERSION LOWERS...AND 
RIDGING BUILDS ACROSS NEW YORK STATE ALONG WITH INCREASING LOW LEVEL 
SHEAR. WILL THEREFORE DROP POPS BACK TO THE LOW CHANCE RANGE IN THE 
LAKE EFFECT AREAS DURING THIS PERIOD...WITH THE REMNANT LAKE ERIE 
SNOWS POSSIBLY LIFTING BACK NORTH TOWARD THE BUFFALO AREA LATER IN 
THE NIGHT AS THE LOW LEVEL FLOW STARTS TO TURN MORE 
WEST-SOUTHWESTERLY. ELSEWHERE...WILL MAINTAIN A GENERALLY DRY 
FORECAST...WITH COLD TEMPERATURES CONTINUING.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
WEDNESDAY WILL BEGIN WITH SFC HIGH PRESSURE ACROSS THE MID ATLANTIC 
STATES. LAKE EFFECT SNOW OFF LAKE ERIE AND ONTARIO WILL DIMINISH 
WITH ADDED WIND SHEAR AS LOW LEVEL WINDS BACK. THE 12Z GFS CONTINUES 
TO SHOW WEAK WAA ACROSS WESTERN NEW YORK AND INTO THE NORTH COUNTY 
ON WEDNESDAY...WHILE THE GGEM AND THE 0Z ECMWF MAINTAINS A DRY 
FORECAST. WILL HAVE LOW CHC POPS WEDNESDAY FOR LIGHT SNOW. 
TEMPERATURES WILL CONTINUE TO REMAIN BELOW NORMAL ON WEDNESDAY EVEN 
THOUGH THEY WILL BEGIN TO MODERATE. 

EXPECT CLOUD COVER WEDNESDAY NIGHT AHEAD OF AN ALBERTA CLIPPER TO 
KEEP TEMPERATURES HIGHER THAN PREVIOUS NIGHTS. A GENERAL AREA OF 
LIGHT SNOW SHOWERS WILL DEVELOP LATER WEDNESDAY NIGHT AND INTO 
THURSDAY AS WARM AIR ADVECTION SETS UP AHEAD OF THE CLIPPER. 

AS THE SFC LOW STALLS LATER IN THE WEEK NEAR THE GREAT LAKES, 
COMBINED WITH A DIGGING SHORT WAVE ACROSS THE GREAT LAKES 
REGION...EXPECT GENERAL SNOW SHOWERS TO CONTINUE THURSDAY NIGHT INTO 
THE WEEKEND WITH EXTENSIVE CLOUD COVER. 

TEMPERATURES THURSDAY AND INTO THE WEEKEND WILL RUN JUST BELOW TO 
NEAR NORMAL.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
STEADY LIGHT RAIN WILL END AS A PERIOD OF WET SNOW THIS EVENING
OVER THE GENESEE VALLEY AND KROC WITH IFR/LIFR CONDITIONS. LOOK
FOR SOME SHARP CLEARING AS A DRY SLOT WORKS INTO WESTERN NY THIS
EVENING. WITH CONDITIONS IMPROVING TO VFR...IMMEDIATELY AT
KBUF/KIAG AND BY 04Z OR SO AT KROC. IMPROVEMENT WILL HOLD OFF
UNTIL 10Z OR SO AT KART. WRAP AROUND MOISTURE WILL ARRIVE BY 18Z
SUNDAY OVER THE FAR WEST WITH A VFR/MVFR CIGS RETURNING. SNOW
SHOWERS WILL BECOME A THREAT TOWARD THE END OF THE 24 HOUR CYCLE
AT KBUF/KIAG...AFTER 19Z SUNDAY...WITH A COLDER SOUTHWEST FLOW 
ADVECTING IN ACROSS LAKE ERIE.

OUTLOOK...
MONDAY...SNOW SHOWERS LIKELY WITH IFR/MVFR.
TUESDAY...MVFR/VFR WITH A CHANCE OF SNOW SHOWERS. LOCAL IFR IN
LAKE EFFECT SNOW SOUTHEAST OF THE LAKES.
WEDNESDAY AND THURSDAY...MVFR/VFR WITH A CHANCE OF SNOW SHOWERS.

&&

.MARINE...
WEAK RIDGING WILL SLOWLY WORK ACROSS NEW YORK STATE TONIGHT... 
RESULTING IN A WEAK PRESSURE GRADIENT AND WINDS/WAVES WELL BELOW 
ADVISORY CRITERIA THROUGH THE NIGHT. THIS RIDGE WILL THEN DRIFT OFF 
TO THE EAST ON SUNDAY...WITH A CYCLONIC FLOW OF COLDER AIR 
OVERSPREADING THE AREA AT ALL LEVELS. THIS WILL RESULT IN SOUTHWEST 
WINDS PICKING UP AGAIN WITH TIME DURING THE DAY...WITH WINDS AND 
WAVES EXPECTED TO PEAK A LITTLE BELOW ADVISORY CRITERIA DURING THE 
AFTERNOON. 

THE NEXT ROUND OF ADVISORY-LEVEL CONDITIONS IS EXPECTED TO ARRIVE 
SUNDAY NIGHT INTO MONDAY AS AN ARCTIC COLD FRONT APPROACHES AND 
CROSSES THE REGION. DURING THIS PERIOD...A BRISK WSW FLOW WILL 
DEVELOP ACROSS BOTH LAKES ERIE AND ONTARIO DURING SUNDAY 
NIGHT...THEN WILL STRENGTHEN FURTHER ON MONDAY BEFORE VEERING 
SHARPLY TO NORTHWEST BEHIND THE FRONTAL PASSAGE LATE MONDAY 
AFTERNOON AND MONDAY EVENING. AT THIS POINT...IT APPEARS THAT AT 
LEAST HIGH END ADVISORY-LEVEL CONDITIONS WILL BE LIKELY DURING THIS 
TIME FRAME...WITH WINDS POSSIBLY REACHING LOW-END GALES. FOR NOW 
WILL JUST HIGHLIGHT THIS POTENTIAL IN THE HWO...WITH THE THOUGHT 
THAT MARINE FLAGS OF SOME SORT WILL LIKELY NEED TO BE ISSUED WITHIN 
THE NEXT 12-24 HOURS.

&&

.HYDROLOGY...
WESTERN NY HAD A GOOD HOLIDAY DRENCHING THE PAST 24-36 HOURS WITH
AMOUNTS CLOSE TO AN INCH OVER THE FAR WEST AND 0.5 TO 0.75 FROM
FINGER LAKES TO NORTH COUNTRY. THIS COMBINED WITH SOME MODEST
SNOWMELT TO RESULT IN GOOD RISES TO AREA RIVERS AND
CREEKS...ESPECIALLY NEAR BUF WHERE THE MAJOR CREEK SHOW 2 TO 4
FOOT RISES. ALL SHOULD CREST BELOW ACTION STAGE TONIGHT. ONE PLUS
FROM THIS THAW IS THAT ANY ICE HAS BEEN FLUSHED OUT OF ALL THE
CREEKS. GROUND IS GENERALLY BARE EVERYWHERE IN WESTERN NY...ASIDE
FROM SOME HIGH ELEVS OF SRN TIER. TUG HILL HAS A DECENT PACK BUT
LOW ELEVS E OF LK ONTARIO HAVE LITTLE/NO SNOW COVER ALSO.

&&

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

&&

$$

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