FXUS61 KBUF 070507
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1207 AM EST MON DEC 7 2009

.SYNOPSIS...
WEAK HIGH PRESSURE WILL PASS ACROSS THE REGION TONIGHT WITH FAIR 
WEATHER CONTINUING ACROSS MOST OF THE REGION...EXCEPT EAST OF LAKE 
ONTARIO WHERE SOME MINOR LAKE EFFECT SNOW SHOWERS WILL PERSIST. 
WEAK LOW PRESSURE WILL THEN PASS ACROSS ON SOUTHERN ONTARIO ON 
MONDAY...BRINGING A LITTLE MORE LIGHT SNOW TO THE NORTH COUNTRY. 
FOLLOWING THIS SYSTEM...MORE LIMITED LAKE EFFECT SNOW SHOWERS WILL 
AFFECT AREAS EAST OF THE LAKES INTO TUESDAY...BEFORE A 
POWERFUL STORM SYSTEM TAKES AIM ON OUR REGION FOR WEDNESDAY AND 
THURSDAY WITH SNOW AND RAIN GIVING WAY TO STRONG WINDS AND MUCH 
COLDER WEATHER.

&&

.NEAR TERM /THROUGH TODAY/...
BAND OF LAKE EFFECT SNOW OFF EAST END OF LAKE ONTARIO MOVING SLGTLY 
SOUTHWARD AS LO1 BUFKIT PROFILE OVER LK ONTARIO INDICATED. THE MM5 
SUPPORTS THIS SOUTHWARD MOVEMENT AS WELL. EXPECT ACTIVITY TO STAY 
MAINLY OVER NORTHERN HALF OF OSWEGO COUNTY AND SOUTHERN JEFFERSON 
COUNTY, JUST SOUTH OF WATERTOWN AND EXTEND INLAND ACROSS THE 
NORTHERN TWO THIRDS OF LEWIS COUNTY. EXPECT 2 TO 3 INCHES IN THE 
MORE PERSISTENT LK SNOWS. MODELS SHOW ACTIVITY SHLD SLOWLY MOVE 
NORTH MONDAY AFTER DAYBREAK.

ELSEWHERE GENLY MID TO HIGH CLOUDS OVERSPREADING THE REGION AHEAD OF 
A TROUGH OVER THE CENTRAL LAKES WHILE HIGH PRESSURE MOVES TO THE MID 
ATLANTIC COAST OVERNIGHT. LOWS GENLY IN THE MID TO UPPER 20S BUT 
UPPER TEENS TO LOWER 20S INTERIOR OF THE SOUTHERN TIER.

REST OF EARLIER DISCO BELOW FOR MONDAY...

FOR MONDAY WE EXPECT THE LAKE EFFECT BANDS TO CONTINUE IN A WEAKENED 
STATE EAST OF LAKE ONTARIO BUT WINDS WILL BE WEAKER WITH INCREASING 
SHEAR SO NO BIG DEAL. CLOUDS WILL BE ON THE INCREASE ELSEWHERE AS 
BOTH THE GFS AND NAM ARE INDICATING A PRONOUNCED VORTICITY MAX 
MOVING INTO OUR REGION LATER IN THE DAY. WE WILL BE IN THE FAVORABLE 
LEFT FRONT QUADRANT OF THE 250 MB JET ASSOCIATED WITH THIS 
DISTURBANCE. WE WILL GO WITH CHANCE POPS FOR SNOW SHOWERS MOST AREAS 
BUT BUMP THE EASTERN LAKE ONTARIO REGION UP TO LIKELY WHERE THE 
GREATEST JET INDUCED LIFT WILL BE FOUND.

AS FAR AS TEMPERATURES GO IT WILL CONTINUE ON THE COLD SIDE WITH 
LOWS IN THE 20S TONIGHT AND HIGHS ONLY IN THE LOW TO MID 30S 
MONDAY.

MAKE SURE TO READ THE SECTIONS BELOW AS THE WEATHER IS LIKELY TO 
BECOME VERY ACTIVE TOWARD MID WEEK.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
DURING MONDAY NIGHT AND TUESDAY...THE WEAK SURFACE WAVE RESPONSIBLE 
FOR MONDAY'S LIGHT SNOWFALL ACROSS THE NORTH COUNTRY WILL QUICKLY 
EXIT ACROSS NEW ENGLAND...WHILE SURFACE RIDGING BUILDS EAST 
ACROSS NEW YORK STATE. AS A RESULT...ANY SYNOPTIC-SCALE SNOW SHOWERS 
SHOULD END FAIRLY QUICKLY ACROSS THE NORTH COUNTRY MONDAY 
EVENING...LEAVING BEHIND JUST SOME LEFTOVER FLURRIES FOR MOST OF THE 
AREA. THE EXCEPTION TO THIS WILL BE IN AREAS EAST AND EAST-SOUTHEAST 
OF LAKES ERIE AND ONTARIO...WHERE A SOMEWHAT SHEARED WESTERLY TO 
WEST-NORTHWESTERLY FLOW OF -10C 850 MB AIR WILL HELP TO GENERATE 
SOME MORE NUISANCE LAKE EFFECT SNOW SHOWERS THROUGH THE NIGHT AND 
INTO TUESDAY MORNING. WHILE THE AFOREMENTIONED RIDGING AND SHEAR 
SHOULD KEEP THIS ACTIVITY FROM BECOMING SIGNIFICANT...IT STILL COULD 
PRODUCE A COUPLE OF INCHES OF ACCUMULATION BEFORE FINALLY FIZZLING 
OUT UNDER INCREASING SUBSIDENCE/SHEAR/DRYING OF THE LOW LEVELS ON 
TUESDAY. OTHERWISE...TUESDAY SHOULD BE A GENERALLY QUIET AND DRY 
DAY...THE PROVERBIAL CALM BEFORE THE NEXT BIG STORM.

THINGS THEN LOOK TO GET MUCH MORE INTERESTING THE REMAINDER OF THE 
FORECAST PERIOD...AS A STRONG SHORTWAVE TROUGH IN THE SOUTHERN 
BRANCH OF THE JET STREAM MOVES OUT OF THE SOUTHERN PLAINS TUESDAY 
NIGHT...WITH AN ATTENDANT DEEPENING SURFACE LOW MOVING FROM SOUTHERN 
KANSAS TO NEAR CHICAGO BY WEDNESDAY MORNING...THEN TO NEAR GEORGIAN 
BAY BY WEDNESDAY EVENING. THE STRONG WARM ADVECTION PATTERN 
DEVELOPING OUT AHEAD OF THIS LOW WILL SPREAD ACROSS NEW YORK STATE 
DURING THE COURSE OF TUESDAY NIGHT AND WEDNESDAY MORNING...WITH A 
60+KT LOW LEVEL JET BOTH HELPING TO SPREAD PLENTY OF MOISTURE INTO 
THE AREA...AS WELL AS LIFT THIS MOISTURE VIA A ZONE OF STRONG 
CONVERGENCE ALONG ITS NOSE. SUPERIMPOSED UPON THIS AREA OF STRONG 
LOW TO MID-LEVEL FORCING WILL ALSO BE A BROAD AREA OF UPPER LEVEL 
DIFFLUENCE/LIFT FROM A COUPLED UPPER LEVEL JET STRUCTURE...RESULTING 
IN DEEP-LAYERED LIFT OF A RATHER MOIST ATMOSPHERIC COLUMN. 
CONSEQUENTLY...WE SHOULD SEE WIDESPREAD PRECIPITATION BREAKING OUT 
ACROSS THE AREA BEGINNING AFTER MIDNIGHT TUESDAY NIGHT IN THE FAR 
WEST...AND EVENTUALLY OVERSPREADING THE REMAINDER OF THE AREA BY 
MID-LATE WEDNESDAY MORNING.

AS FOR PTYPE...THE 12Z MODEL SOUNDINGS AND MOS GUIDANCE UNIVERSALLY 
SUGGEST THAT THE ATMOSPHERE WILL REMAIN COLD ENOUGH TO SUPPORT ALL 
SNOW THROUGH 12Z WEDNESDAY. WITH QPFS OF A QUARTER TO A THIRD OF AN 
INCH A DISTINCT POSSIBILITY ACROSS THE WESTERN PART OF THE AREA BY 
WEDNESDAY MORNING...IT IS QUITE POSSIBLE THAT THE NIAGARA FRONTIER 
AND WESTERN SOUTHERN TIER COULD PICK UP AS MUCH AS 2-4 INCHES OF 
SNOW BY DAYBREAK ON WEDNESDAY. 

THEREAFTER...THE CONTINUED STRONG WARM ADVECTION OUT AHEAD OF THE 
DEEPENING LOW SHOULD LEAD TO A GRADUAL SOUTHWEST TO NORTHEAST 
TRANSITION FROM SNOW TO RAIN DURING THE COURSE OF WEDNESDAY FOR MOST 
OF THE AREA...AS 850 MB TEMPS RISE INTO THE +2C TO +4C RANGE AND 
SURFACE READINGS CLIMB INTO THE UPPER 30S AND LOWER 40S. THIS 
TRANSITION SHOULD OCCUR ACROSS THE WEST DURING THE LATE 
MORNING...MIDDAY TO EARLY AFTERNOON ACROSS OUR CENTRAL ZONES...AND 
DURING THE MID TO LATE AFTERNOON ACROSS THE EAST. PRIOR TO THIS 
CHANGEOVER...SEVERAL MORE INCHES OF SNOW ARE LIKELY TO ACCUMULATE 
ACROSS THE AREA...WITH THE EXACT TIMING OF THE CHANGEOVER PLAYING A 
KEY ROLE IN DETERMINING THE AMOUNT OF ADDITIONAL ACCUMULATION.

WHILE THE MAIN AREA OF JET-INDUCED LIFT WILL LIFT OFF TO THE NORTH 
DURING WEDNESDAY AFTERNOON...IT WILL BE QUICKLY REPLACED BY THE 
FORCING ASSOCIATED WITH AN APPROACHING STRONG COLD FRONT THAT WILL 
WRAPPING AROUND THE SOUTHERN SIDE OF THE DEEPENING LOW. THIS SHOULD  
RESULT IN LITTLE...IF ANY...BREAK IN THE PRECIPITATION DURING THE 
COURSE OF WEDNESDAY AFTERNOON...THEREFORE HAVE JUST KEPT BROADBRUSH 
CATEGORICAL POPS IN PLACE FOR THE ENTIRE DAY AT THIS TIME. 

CURRENT INDICATIONS ARE THAT THE COLD FROPA ITSELF WILL BEGIN IN THE 
20-21Z TIME FRAME ACROSS FAR WESTERN NEW YORK STATE...WITH THE FRONT 
REACHING THE GENESEE VALLEY/FINGER LAKES BY EVENING. WITH THE 
FRONTAL PASSAGE...50-55 KT WINDS ALOFT MAY BE MIXED TO THE 
SURFACE...USHERING IN THE BEGINNING OF A VERY WINDY AND UNSETTLED 
PERIOD. MORE ON THAT BELOW...

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
DURING WEDNESDAY NIGHT...THE POWERFUL LOW PRESSURE SYSTEM NEAR 
GEORGIAN BAY WILL LIFT NORTHEAST TO THE ONTARIO-QUEBEC BORDER...WITH 
ITS ASSOCIATED COLD FRONT QUICKLY PLOWING THROUGH THE REMAINDER OF 
THE AREA EARLY WEDNESDAY EVENING. BEHIND THIS FRONT...MUCH COLDER 
AIR WILL SURGE ACROSS THE AREA...WITH THE STRONG CAA REGIME/ 
ASSOCIATED DOWNWARD MOMENTUM TRANSPORT LEADING TO THE DEVELOPMENT OF 
VERY WINDY CONDITIONS. BUFKIT PROFILES AND NAM/GFS PAN VIEWS 
CONTINUE TO SHOW WINDS MAXING OUT IN THE 50-55 KT RANGE IN THE 
LOWEST 3-7 KFT OF THE ATMOSPHERE...WHICH SHOULD BE GOOD ENOUGH FOR 
AT LEAST A SOLID ROUND OF ADVISORY-CRITERIA WINDS FOR WEDNESDAY 
NIGHT AND THURSDAY. 

IN CONJUNCTION WITH THE STRONG WINDS...-16C TO -18C AIR AT 850 MB 
WILL ALSO POUR ACROSS THE LOWER GREAT LAKES. THIS WILL BE THE 
COLDEST AIRMASS OF THE SEASON BY FAR...AND WILL PRODUCE FAIRLY 
WIDESPREAD LAKE EFFECT SNOW SHOWERS TO THE LEE OF BOTH LAKES ERIE 
AND ONTARIO. CURRENT INDICATIONS ARE THAT THE LAKE SNOWS WILL 
INITIALLY SET UP NORTHEAST OF THE LAKES LATER WEDNESDAY NIGHT/EARLY 
THURSDAY ON A PREVAILING WSW FLOW...POTENTIALLY SETTING THE STAGE 
FOR A VERY UGLY THURSDAY MORNING COMMUTE OWING TO THE COMBINATION OF 
THE LAKE SNOWS AND CONTINUED STRONG WINDS. AFTER POSSIBLY LINGERING 
NORTHEAST OF THE LAKES THROUGH THURSDAY MORNING...THE LAKE SNOWS 
SHOULD THEN SLOWLY DRIFT SOUTH THURSDAY AFTERNOON AND EVENING AS THE 
FLOW BECOMES MORE WESTERLY. THEREAFTER...A GENERAL WESTERLY FLOW OF 
CONTINUED COLD AIR IS EXPECTED TO PERSIST THROUGH SATURDAY...HELPING 
TO KEEP POTENTIALLY SIGNIFICANT LAKE SNOWS GOING ACROSS THE 
TRADITIONAL SNOWBELT AREAS TO THE EAST OF BOTH LAKES.  

THE STRETCH OF BELOW NORMAL TEMPERATURES AND ASSOCIATED LAKE SNOWS 
WILL THEN FINALLY BEGIN TO WIND DOWN ON SUNDAY...AS THE CROSS-POLAR 
FLOW FROM THE YUKON BEGINS TO BREAK DOWN AND BECOME MORE PACIFIC IN 
NATURE ONCE AGAIN.

&&

.AVIATION /05Z MONDAY THROUGH FRIDAY/...
MUCH OF THE REGION FROM THE FINGER LAKES WEST SHOULD BE MAINLY VFR 
THROUGH THE MORNING HOURS ALTHOUGH AROUND KIAG A PERIOD OF MVFR CIGS 
IS EXPECTED FROM AROUND 09Z-13Z. THE EXCEPTION IS THE CONTINUING 
LAKE EFFECT EAST OF LAKE ONTARIO. THAT WILL CONTINUE TO PRODUCE MVFR 
TO IFR CONDITIONS IN SNOW THROUGH MUCH OF THE MORNING BUT HTE 
HEAVIER ACTIVITY SHLD STAY JUST SOUTH OF KART.

MONDAY MORNING AN AREA OF LOW PRESSURE IS EXPECTED TO MEVE EAST FROM 
THE CENTRAL GRT LKS ACROSS SOUTHERN ONTARIO TO JUST NORTH OF MASSENA 
BY EVENING. THIS FEATURE WILL BRING A PERIOD OF MVFR CONDITIONS 
ACROSS AREAS NORTH OF THE THRUWAY WITH SOME OCNL S- DURG THE COURSE 
OF THE AFTERNOON FOR THE KIAG AND KROC TAF SITES. AT THIS TIME WILL 
KEEP AREAS FROM BUFFALO SOUTHWARD VFR ALTHOUGH THERE IS A CHANCE OF 
SNOW SHOWERS IN THE AFTERNOON.

ACROSS THE NORTH COUNTRY THE LAKE SNOWS ARE EXPECTED TO LIFT NORTH 
DURING THE MORNING AS STEERING WINDS BECOME MORE SW TO S. THE LAKE 
SNOWS SHLD MOVE NORTH ACROSS THE KART REGION LOWERING CONDITIONS TO 
IFR/LIFR DURG THE AFTERNOON. SNOW ASSOCIATED WITH THE LOW 
APPROACHING FROM THE CENTRAL LKS WILL ALSO CONTRIBUTE TO THESE LOWER 
CONDITIONS ESPECIALLY ACROSS AREAS FROM WATERTOWN TO THE ST LAW 
VALLEY. 

SOME LAKE ENHANCED SNOWS ARE EXPECTED TO DEVELOP OFF LK ERIE THAT 
WILL BRING MVFR TO IFR CONDITIONS ACROSS THE SOUTHERN TIER IN THE 
EVENING WITH OCNL MVFR CONDITIONS AT KBUF. 

OUTLOOK...
LATER MONDAY NIGHT...VFR. MVFR/IFR IN LK SNOWS EAST OF THE LAKES. 
TUESDAY...VFR.
WEDNESDAY...MVFR/IFR WITH RAIN/SNOW. POSSIBLE LOW LEVEL WIND SHEAR.
THURSDAY...MVFR/IFR SNOW SHOWERS. STRONG SURFACE WINDS LIKELY.

&&

.MARINE...
ISSUED SMALL CRAFT ADVSRY FOR BUFFALO TO RIPLEY ALNG LK ERIE THROUGH 
4AM. RATHER BRISK SW WINDS ON EAST END OF LAKE PRODUCING WAVES IN 
SMALL CRAFT ADVSRY RANGE. THEY SHLD DIMINISH TOWARD DAYBREAK.

SMALL CRAFT ADVISORIES REMAIN IN PLACE FOR THE NEW YORK NEARSHORE 
WATERS OF LK ONTARIO THROUGH MOST OF TONIGHT AS A FAIRLY TIGHT  
PRESSURE GRADIENT WILL BE FOUND BETWEEN HIGH PRESSURE CENTERED OVER 
THE VIRGINIAS AND A LOW NEAR JAMES BAY. THE GRADIENT WILL RELAX 
LATER TONIGHT WITH CONDITIONS IMPROVING FROM WEST TO EAST.

ATTENTION WILL THEN TURN TO A POWERFUL EARLY WINTER STORM THAT WILL 
LIKELY PRODUCE GALE FORCE WINDS AND WAVES IN EXCESS OF 10 FEET 
ACROSS BOTH LAKES WEDNESDAY NIGHT AND THRUSDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST EARLY THIS MORNING FOR 
         LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 3 AM EST EARLY THIS 
         MORNING FOR LOZ042-043.
         SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR 
         LOZ045.
         SMALL CRAFT ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR 
         LOZ044.

&&

$$

SYNOPSIS...JJR
NEAR TERM...JJP/SAGE
SHORT TERM...JJR
LONG TERM...JJR/RSH
AVIATION...JJP/JJR
MARINE...JJP/JJR/SAGE