FXUS61 KBUF 271023
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
523 AM EST FRI NOV 27 2009

.SYNOPSIS...
LOW PRESSURE CENTERED NEAR CAPE COD THIS MORNING WILL TRACK 
NORTHWARD AND DEEPEN RAPIDLY...REACHING THE CANADIAN MARITIMES BY 
SATURDAY MORNING. THIS WILL DRAW COLDER CANADIAN AIR SOUTHWARD 
ACROSS OUR REGION AND PRODUCE BRISK WINDS. A WEAK RIDGE OF HIGH 
PRESSURE WILL BUILD OVER US SATURDAY NIGHT. TEMPERATURES WILL 
MODERATE A BIT SUNDAY AS A WEAK LOW MOVES EAST FROM THE CENTRAL 
LAKES REGION. A COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL MOVE 
THROUGH THE AREA EARLY MONDAY FOLLOWED BY ANOTHER SHOT OF COLD AIR.

&&

.NEAR TERM /THROUGH TONIGHT/...
AN UPPER LEVEL LOW ACROSS THE LOWER LAKES WILL SLOWLY MOVE EAST AS A 
DEEPENING LOW PRESSURE MOVES NORTHEAST ALONG THE NEW ENGLAND COAST.  
AN INVERTED TROF EXTENDING NW INTO NORTHERN NY WILL KEEP PLENTY OF 
MOISTURE OVER CENTRAL AND NORTHERN NY WHERE WILL CONTINUE WITH CAT 
POPS. A COUPLE OF INCHES OF SNOW IS POSSIBLE ACROSS THE HIGHER 
TERRAIN MNLY OVER LEWIS COUNTY TODAY. 

A NORTHWEST FLOW OF MOIST AIR WRAPPING ARND THE LOW OVER THE REST OF 
WESTERN NEW YORK WILL BRING A THREAT OF PRECIPITATION TO THE REST OF 
WESTERN NEW YORK AND THE FINGER LKS. WILL CONTINUE WITH CATEGORICAL 
POPS IN THE FAVORED UPSLOPE AREA EAST OF LAKE ERIE TO THE SOUTH OF 
BUFFALO ON THE CHAUTAUQUA RIDGE. SNOWFALL ACCUMS OF A COUPLE OF 
INCHES ARE POSSIBLE ESPCIALLY OVER THE HILLTOPS. ELSEWHERE WILL GO 
WITH CHC POPS OVER MOST OF THE REST OF THE AREA. HIGHS TODAY SHLD 
RANGE FROM THE MID TO UPPER 30S OVER THE HIGHER TERRAIN SOUTH OF 
BUFFALO WITH LOWER 40S TO MID 40S OVER MUCH OF THE REST OF THE 
REGION EXCEPT SOME UPPER 30S ACROSS THE HIGHER TERRAIN EAST OF LAKE 
ONTARIO.  

TONIGHT, THE DEEPENING LOW OFF THE MAINE COAST WILL CONTINUE TO MOVE 
NORTHEAST WITH SOME WRAP AROUND PRECIP OVER THE REGION. THE BULK OF
PRECIP WILL BE FROM AREAS EAST OF THE GENESEE VALLEY, EASTWARD 
ACROSS CENTRAL NY AND NORTHERN NY. IN THESE AREAS WILL CARRY 
LKLY/CAT POPS WITH THE PRECIP TAPERING OFF LATER AT NGT ACROSS THE 
FINGER LKS. ACROSS THE HIGHER TERRAIN EAST OF LK ONTARIO EXPECT 
GENLY 1 TO 3 INCHES OF SNOW ACCUMULATION AT THIS TIME. THIS MAY
HAVE TO BE ADJUSTED BY LATER FORECASTS. ELSEWHERE A RAIN/SNOW MIX
IS EXPECTED OVERNIGHT WITH LITTLE OR NO ACCUM.

THE NORTHWESTERLY UPSLOPE FLOW ACROSS THE HILLS OF THE SOUTHERN TIER 
WILL CONTINUE. I EXPECT THE UPSLOPE PRECIP TO CONTINUE BUT IT SHLD 
WEAKEN LATER AT NGT AS THE INVERSION HEIGHT LOWERS AND WE LOSE THE 
CRYSTAL GROWTH REGION. ALSO WITH THE NW WINDS INCREASING, RESIDENCY 
TIME OVER THE LK WILL BE BRIEF. EXPECT AMNTS GENLY AN INCH OR LESS.

THE OTHER ISSUE WILL BE THE INCREASING WINDS LATER THIS AFTERNOON
AND INTO TONIGHT AS THE PRESSURE GRADIENT TIGHTENS. NW WINDS WILL
INCREASE TO 15 TO 25 MPH LATER THIS AFTERNOON AND 15 TO 30 MPH
TONIGHT WITH SOME GUSTS TO 35 MPH.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
A CYCLONIC FLOW OF COLD AIR WILL CONTINUE SATURDAY MORNING ON THE 
BACK SIDE OF A VERY DEEP SURFACE LOW OVER THE CANADIAN MARITIMES BUT 
LAKE INDUCED CAPES WILL BE SMALL ALONG WITH DROPPING EQUILIBRIUM 
LEVELS AND VERY LITTLE MOISTURE IN THE SNOW GROWTH AREA. WE WILL 
KEEP CHANCE POPS FOR AWHILE SOUTHEAST OF THE LAKES BUT THEN DIMINISH 
THEM AS HIGH PRESSURE BUILDS EAST FROM THE CENTRAL LAKES REGION. 
SYNOPTIC SCALE FORCING MAY STILL BE AROUND EARLY OVER THE EASTERN 
LAKE ONTARIO REGION BUT IT SHOULD MOVE OFF QUICKLY WITH THE 
DEPARTING LOW. IN GENERAL THE DAY WILL BE CHARACTERIZED BY MOSTLY 
CLOUDY SKIES AND BRISK WINDS. TEMPERATURES WILL BE NEAR NORMAL FOR 
THIS TIME OF YEAR BUT QUITE A BIT COLDER THAN WHAT WE HAVE BECOME 
ACCUSTOMED TO THIS MONTH.  

BOTH THE GFS AND NAM CONTINUE TO SHOW A WEAK SURFACE RIDGE BUILDING 
OVER US SATURDAY NIGHT AS A BROAD FLAT UPPER RIDGE PROGRESSES 
EASTWARD FROM THE CENTRAL LAKES REGION. WINDS WILL BE ON THE 
DECREASE AND SOME PARTIAL CLEARING SHOULD TAKE PLACE AS SUBSIDENCE 
ERODES LOW LEVEL CLOUDINESS.

SUNDAY IS STILL A BIT IN QUESTION. THE GFS DEVELOPS A SHORT WAVE IN 
THE ZONAL UPPER FLOW OVER THE CENTRAL LAKES MORE THAN THE NAM. THIS 
WILL LEAD TO LOWERING SURFACE PRESSURE JUST TO OUR WEST. ONE THING 
FOR SURE IS THAT IT WILL BE A BIT MILDER AS 850 MB TEMPERATURES ARE 
PROGGED TO RISE ABOVE ZERO CELSIUS. CLOUDS WILL BE ON THE INCREASE 
AGAIN BUT NOTHING HIGHER THAN CHANCE POPS AT THIS TIME AS THE 
CENTRAL GREAT LAKES LOW MOVES SLOWLY EAST.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
ANOTHER SHOT OF COLD AIR WILL FOLLOW THE THE GREAT LAKES LOW LATE 
SUNDAY NIGHT AND MONDAY. WE WILL HAVE TO BE CONCERNED WITH SCATTERED 
PRECIPITATION ACCOMPANYING THE COLDER AIR MASS WITH SOME LAKE 
INDUCED CAPE BECOMING INVOLVED AGAIN. AT THIS TIME IT DOESN'T LOOK 
LIKE ANYTHING TOO SERIOUS BUT A WEST NORTHWEST FLOW MONDAY NIGHT 
INTO TUESDAY MORNING MAY LEAD TO ACCUMULATING SNOWS OVER THE HILLS 
OF THE SOUTHERN TIER AND EAST OF LAKE ONTARIO.

THE COLD SHOT WILL BE BRIEF WITH WARM ADVECTION SCHEDULED ONCE AGAIN 
TUESDAY AFTERNOON INTO WEDNESDAY. JUST CHANCE POPS EAST OF THE LAKES 
EARLY TUESDAY OTHERWISE FAIR THROUGH WEDNESDAY NIGHT.

WE WILL KEEP CHANCE POPS FOR THURSDAY WITH PLENTY OF UNCERTAINTY ON 
WHAT HAPPENS TO THE SOUTHERN STREAM ENERGY. THE 00Z RUN OF THE GFS 
KEEPS THE PRECIPITATION SHIELD SOUTH OF US WITH 850 MB TEMPERATURES 
IN THE MINUS 8C RANGE WHILE THE ECMWF HAS A SURFACE LOW PASSING JUST 
TO THE SOUTH OF US WITH 850 TEMPS WARMER THAN 0C. 

FURTHER OUT...BOTH GFS AND ECMWF SHOW WESTERLY FLOW OF INCREASINGLY 
COLDER AIR AROUND STRONG VORTEX OVER UPPER LAKES FROM LATE THURSDAY 
INTO THE FOLLOWING WEEKEND. SUCH A PATTERN WOULD SERVE TO TURN ON 
THE LONG OVERDUE LAKE EFFECT MACHINE FOR US. STAY TUNED.

&&

.AVIATION /10Z 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...
WINDS WILL BE ON THE INCREASE TODAY AS LOW PRESSURE DEEPENS RAPIDLY 
ALONG THE NEW ENGLAND COAST. SMALL CRAFT ADVISORIES WILL BE NEEDED 
FOR MOST AREAS LATER TODAY INTO SATURDAY. SUSTAINED WINDS OVER THE 
LAKES WILL APPROACH GALE FORCE AND SOME GUSTS WILL BE ABOVE GALE 
FORCE.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 1 PM EST 
         SATURDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 10 AM EST 
         SATURDAY FOR LEZ020.
         SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 7 PM 
         EST SATURDAY FOR LOZ042>045.
         SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 1 PM 
         EST SATURDAY FOR SLZ022-024.

&&

$$

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