FXUS61 KBUF 120433
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1133 PM EST FRI DEC 11 2009

.SYNOPSIS...
LOCALLY HEAVY LAKE EFFECT SNOW WILL CONTINUE IN THE SNOWBELTS EAST 
OF THE LAKES TONIGHT BEFORE ENDING ON SATURDAY MORNING EAST OF LAKE 
ERIE AND BY SATURDAY EVENING EAST OF LAKE ONTARIO. ELSEWHERE MAINLY 
DRY CONDITIONS WILL CONTINUE THROUGH SATURDAY NIGHT AS A RIDGE OF 
HIGH PRESSURE BUILDS OVER THE LOWER LAKES. A WEAK AREA OF LOW 
PRESSURE WILL MOVE THROUGH THE GREAT LAKES REGION SUNDAY AND BRING 
THE NEXT CHANCE OF PRECIPITATION ALONG WITH WARMER TEMPERATURES. THE 
WARM TEMPERATURES WILL LAST THROUGH THE FIRST FEW DAYS OF NEXT WEEK 
BEFORE ANOTHER SURGE OF COLD AIR ARRIVES BY WEDNESDAY.

&&

.NEAR TERM /THROUGH SATURDAY/...
LAKE SNOW IS WEAKENING OVER THE WESTERN SOUTHERN TIER AS DRIER AIR 
MOVES INTO THE REGION. WILL DROP THE LAKE SNOW WARNING AND REDUCE 
THE OVERNIGHT SNOW ACCUMULATIONS TO A 2 TO 4 INCH RANGE. WINDS WILL 
SHIFT TO SOUTHWEST LATE TONIGHT AND INTO SATURDAY AND THERE COULD BE 
A SEVERAL HOUR PERIOD WHEN THE LINGERING LAKE SNOW LIFTS NORTHWARD 
INTO THE BUFFALO METRO AREA..MUCH WEAKER AND MORE DISPERSED.  

MEANWHILE OFF OF LAKE ONTARIO...AN INTENSE SINGLE LAKE EFFECT SNOW 
CONTINUES ACROSS NORTHERN OSWEGO AND MUCH OF LEWIS COUNTIES...WITH 
RADAR-ESTIMATED SNOWFALL RATES OF 3 TO 5" PER HOUR COMMONPLACE 
ACROSS TUG HILL PLATEAU. THE SNOW BAND HAS SETTLED SOUTH OF 
JEFFERSON COUNTY...THUS THE LAKE SNOW WARNING HAS BEEN DISCONTINUED 
FOR JEFFERSON COUNTY. THE BAND SHOULD STAY PRETTY MUCH IN PLACE 
THROUGH EARLY TONIGHT...ALTHOUGH IT MAY DROP A LITTLE FARTHER TO THE 
SOUTH OVERNIGHT AND SATURDAY MORNING AS THE STEERING FLOW VEERS TO 
AROUND 280 DEGREES. THE SOUTHERN EDGE OF THE LAKE PLUME COULD SHIFT 
AS FAR SOUTH AS NORTHERN WAYNE AND NORTHERN CAYUGA COUNTIES AND 
LATER SHIFTS MAY NEED TO MONITOR THIS SCENARIO. FOR NOW WILL SUGGEST 
2 TO 4 INCH AMOUNTS IN THESE AREAS. DUE TO THE FULL FETCH OF THE 
LAKE REALIZED FELL THAT ADDITIONAL AMOUNTS OF 1 TO 2 FEET WILL BE 
LIKELY ACROSS THE TUG HILL TONIGHT THROUGH SATURDAY MORNING. LAKE 
EFFECT SNOW WARNINGS WILL REMAIN FOR THIS AREA AS WELL.

WINDS WILL NOT BE AS STRONG AS THEY HAVE BEEN OVER THE PAST 36 PLUS 
HOURS...BUT WINDY TO BREEZY CONDITIONS WILL STILL PERSIST THROUGH AT 
LEAST THE FIRST HALF OF THE NIGHT. SOME BLOWING AND DRIFTING SNOW 
WILL ALSO CONTINUE IN AREAS THAT RECEIVED THE HEAVIER LAKE SNOWS 
YESTERDAY...THOUGH THIS SHOULD NOT BE QUITE AS BAD AS WITHIN THE 
LAKE SNOWS THEMSELVES.

MINIMUM TEMPERATURES TONIGHT FALLING INTO THE TEENS AND COMBINED 
WITH THE WINDS WILL CREATE WIND CHILLS FROM ZERO TO NEAR 10 BELOW 
AT TIMES.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AT THE START OF THE PERIOD A RIDGE OF HIGH PRESSURE WILL BE CROSSING 
THE LOWER LAKES. TEMPERATURES ALOFT WILL BE WARM ENOUGH TO END LAKE 
EFFECT OFF LAKE ERIE. OFF LAKE ONTARIO...850MB TEMPS ARE STILL 
AROUND -8C AT 00Z SUNDAY. THIS MAY BE COLD ENOUGH TO STILL SUPPORT 
SOME VERY LIMITED LAKE RESPONSE...ALTHOUGH ANTICYCLONIC CURVATURE 
AND A LOWERING SUBSIDENCE INVERSION SHOULD KEEP THIS ACTIVITY VERY 
LIGHT. WILL CARRY CHANCE POPS INTO THE EVENING EAST OF THE LAKE 
BEFORE ENDING BY MIDNIGHT AS THE AIRMASS CONTINUES TO MODERATE.

THE NEXT SHORTWAVE AND ASSOCIATED WEAK SURFACE LOW WILL MOVE THROUGH 
THE CENTRAL LAKES ON SUNDAY. THIS SYSTEM IS OF PACIFIC ORIGIN...WITH 
THE AIRMASS QUICKLY MODERATING AHEAD OF THE SYSTEM. PREFER THE 
WARMER NAM PROFILES THAT WARM 850MB TEMPS WELL ABOVE FREEZING ON 
SUNDAY GIVEN THE PATTERN RECOGNITION OF A LOW GOING UP TO OUR WEST. 
AT THE SAME TIME...SOUTHERLY DOWNSLOPE WINDS WILL ALSO ALLOW THE 
BOUNDARY LAYER TO QUICKLY WARM ACROSS THE LOWER ELEVATIONS OF THE 
LAKE PLAIN. THIS SHOULD ALLOW MOST OF THE EXPECTED PRECIP TO FALL AS 
RAIN ON SUNDAY ACROSS THE LOWER ELEVATIONS. ACROSS THE INTERIOR 
SOUTHERN TIER COLD AIR MAY REMAIN TRAPPED IN THE INTERIOR VALLEYS 
LONG ENOUGH TO ALLOW PRECIP TO START AS SOME FREEZING RAIN AND 
PERHAPS A LITTLE SLEET OR SNOW IF PRECIP ARRIVES EARLY ENOUGH. THIS 
SHOULD QUICKLY CHANGE TO RAIN BY LATE MORNING AS THE COLD AIR IS 
SCOURED OUT. MAY SEE A SIMILAR TREND EAST OF LAKE ONTARIO WHERE 
PRECIP MAY BRIEFLY START AS A LITTLE FREEZING RAIN...SLEET...OR SNOW 
BEFORE CHANGING TO RAIN. ANY AMOUNTS WILL BE LIGHT...BUT WILL NEED 
TO MONITOR FOR A POTENTIAL ADVISORY WHEN THE EVENT DRAWS CLOSER. 

SUNDAY NIGHT THE RAIN WILL GRADUALLY END FROM WEST TO EAST ACROSS 
THE AREA. TEMPERATURES REMAIN QUITE MILD WITH NO STRONG COLD AIR 
ADVECTION BEHIND THIS FEATURE...SO EXPECT MOST OF THE PRECIP TO 
REMAIN RAIN BEFORE ENDING. MAY SEE A FEW WET FLAKES MIX IN ACROSS 
THE HIGHER TERRAIN EAST OF LAKE ONTARIO AND ALSO ON THE HILLS OF THE 
SOUTHERN TIER. WILL ALSO NEED TO MONITOR FOR POTENTIAL FREEZING 
DRIZZLE IF DEEP LOW LEVEL MOISTURE FIELDS OF THE NAM VERIFY. ON 
MONDAY A WEAK RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE LOWER 
LAKES. THIS WILL BRING A RARE DRY DAY WITH TEMPS ALOFT NOT COLD 
ENOUGH TO SUPPORT ANY LAKE RESPONSE. SHOULD SEE AT LEAST A LITTLE 
SUN IN THE MORNING BEFORE MID CLOUDS BEGIN TO INCREASE AGAIN AHEAD 
OF THE NEXT SYSTEM. 

MONDAY NIGHT THE NEXT PACIFIC LOW WILL MOVE EAST ACROSS THE GREAT 
LAKES. ONCE AGAIN THIS LOW WILL PASS BY TO OUR NORTH. THIS SHOULD 
ALLOW MOST OF THE PRECIP TO FALL AS JUST RAIN ACROSS MOST OF THE 
AREA. ONE EXCEPTION MAY BE ACROSS THE NORTH COUNTRY AGAIN WHERE 
TEMPS ALOFT ARE A LITTLE COLDER AND THE BOUNDARY LAYER MAY STILL BE 
BELOW FREEZING. THIS MAY RESULT IN A WINTRY MIX IN THAT AREA.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AN AREA OF LOW PRESSURE WILL MOVE FROM THE UPPER LAKES INTO QUEBEC 
DURING THE DAY TUESDAY...DEEPENING IN THE PROCESS AS THE ASSOCIATED 
MID LEVEL TROUGH SHARPENS AND DIGS SOUTHEAST. COLD AIR WILL RUSH 
BACK INTO THE AREA LATER TUESDAY THROUGH THE END OF THE PERIOD WITH 
850MB TEMPS DROPPING INTO THE MID TEENS BELOW ZERO CELSIUS AGAIN. 
THIS WILL BRING TEMPERATURES BACK BELOW NORMAL AGAIN FOR WEDNESDAY 
THROUGH FRIDAY WITH MORE LAKE EFFECT SNOW. THIS TIME...THE FLOW 
APPEARS TO BE MORE NORTHWEST AT THIS EARLY JUNCTURE...WHICH WOULD 
SUGGEST A MORE LIMITED LAKE RESPONSE TO THE SOUTHEAST OF THE LAKES. 

RAIN WILL CHANGE TO SNOW DURING THE DAY TUESDAY WITH FALLING TEMPS 
IN THE AFTERNOON. AFTER THAT...WILL CARRY CHANCE POPS WEDNESDAY AND 
THURSDAY WITH LIKELY TO THE SOUTHEAST OF THE LAKES. BY FRIDAY THE 
FORECAST UNCERTAINTY INCREASES QUICKLY WITH A COMPLEX INTERACTION 
BETWEEN THE NEXT PACIFIC WAVE AND A DEEP TROUGH OVER ATLANTIC 
CANADA. WILL JUST INDICATE A CHANCE OF SNOW FRIDAY TO INDICATE THIS 
POTENTIAL.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
THE SNOW BAND OFF LAKE ERIE WILL REMAIN SOUTH OF THE KBUF
TERMINAL AND WEAKEN GRADUALLY OVERNIGHT. EXPECT VFR CONDITIONS TO
PREVAIL THROUGH MOST OF THE TAF PERIOD VCNTY KBUF AND KIAG
ALTHOUGH THERE MAY BE A SHORT PERIOD IN THE AFTERNOON BETWEEN 18Z
AND 21Z WHEN DISRUPTED LAKE SNOW WILL MOVE THROUGH BEFORE
DISSIPATING COMPLETELY.

FARTHER SOUTH AT KJHW...INCREASING SHEAR AND DRY AIR WILL WEAKEN THE 
LAKE SNOW EARLY TONIGHT AND LIFT NORTH AFTER 10Z THIS MORNING. 

EAST OF LAKE ONTARIO...THE INTENSE SNOW BAND WILL STAY SOUTH OF 
KART. THEREFORE...EXPECT MAINLY VFR CONDITIONS AT THIS SITE. THE 
WEAKENING LAKE SNOW BAND MAY LIFT NORTH ENOUGH TO AFFECT KART 
BETWEEN 15Z AND 19Z ON SATURDAY WITH MVFR CONDITIONS.

BRISK WEST TO SOUTHWEST SURFACE WINDS WILL SUBSIDE SOMEWHAT TONIGHT
AND SATURDAY AS HIGH PRESSURE RIDGES EAST ACROSS THE MIDDLE ATLANTIC 
STATES. 

OUTLOOK...
SATURDAY NIGHT...VFR  
SUNDAY...VFR/MVFR IN SHOWERS AND POSSIBLE MIXED PCPN.
MONDAY...VFR. 
TUESDAY...VFR/MVFR WITH CHANCE OF SHOWERS 
WEDNESDAY...VFR/MVFR IN SNOW SHOWERS.

&&

.MARINE...
WINDS WILL CONTINUE TO DIMINISH OVERNIGHT...DROPPED ALL GALES AND 
REPLACED THEM WITH SMALL CRAFT ADVISORIES...THROUGH 11 AM SAT ON THE
ERIE AND WESTERN LAKE ONTARIO NEARSHORES AND UNTIL 4 PM SATURDAY ON 
THE EASTERN LAKE ONTARIO NEARSHORES.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW WARNING UNTIL 1 PM EST SATURDAY FOR NYZ006-
     008.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EST SATURDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 11 AM EST SATURDAY FOR 
         LOZ042-043.
         SMALL CRAFT ADVISORY UNTIL 4 PM EST SATURDAY FOR LOZ044-
         045.

&&

$$

SYNOPSIS...HITCHCOCK
NEAR TERM...TMA/WCH
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...WCH
MARINE...HITCHCOCK/TJP