Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 242338
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
638 PM EST TUE NOV 24 2009

.SYNOPSIS...
A SOUTHERLY FLOW OF MILD AND RELATIVELY MOIST AIR WILL CONTINUE
ACROSS WESTERN AND CENTRAL NEW YORK THROUGH THANKSGIVING DAY. THERE
WILL BE THE RISK OF A FEW SHOWERS WEDNESDAY AFTERNOON AND AGAIN
LATER ON THURSDAY BUT IT WILL BE DRY MOST OF THE TIME. COMPLEX LOW
PRESSURE WILL DEVELOP OVER SOUTHERN ONTARIO AND LAKE ERIE THURSDAY
NIGHT AND DEEPEN AS IT MOVES EAST AND OFF THE NEW ENGLAND COAST BY
EARLY SATURDAY. THIS WILL RESULT IN AN INCREASING CHANCE OF RAIN
THURSDAY NIGHT WHICH MAY TURN TO WET SNOW OVER HIGHER ELEVATIONS BY
FRIDAY MORNING. COLDER AIR WILL FOLLOW FRIDAY AND SATURDAY WITH
DIMINISHING PRECIPITATION.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
A SEASONABLY COOL AND MOIST PATTERN HAS SETTLED OVER THE EASTERN
THIRD OF THE NATION. HIGH PRESSURE HAS MOVED EASTWARD TO THE
CANADIAN MARITIME PROVINCES AND LOW PRESSURE S ESTABLISHED OVER THE
NATION`S MIDSECTION. THE BROAD SOUTH/SOUTHEASTERLY FLOW BETWEEN
THESE SYSTEMS WILL MAINTAIN THE LOW TO MIDDLE LEVEL MOISTURE ACROSS
THE REGION.

LINGERING DRIZZLE WEST OF SYRACUSE SHOULD COME TO AN END...ONLY
LINGERING IN A FEW SPOTS INTO THIS EVENING. PATCHY FOG MAY DEVELOP
LATE THIS EVENING AND TONIGHT...DEPENDING ON BREAKS IN THE CLOUD
COVER...AND IF WINDS AT THE SURFACE CAN GO CALM. BEST CHANCE FOR
FOG LOOKS TO BE IN THE SOUTHERN TIER.

A WEAK WARM/STATIONARY FRONT FROM CENTRAL PA TO WEST CENTRAL NY WILL
KEEP THE CHANCE OF LIGHT SHOWERS OR DRIZZLE OVER THE CENTRAL AND
WESTERN SOUTHERN TIER TO THE SOUTHWESTERN FINGER LAKES THROUGH THE
OVERNIGHT HOURS. THE NEXT PRECIP PATTERN WILL ARRIVE ON WEDNESDAY AS
THE PLAINS TROUGH MOVES TO THE MIDWESTERN STATES AND LIFTS BETTER
LOW TO MID LEVEL FORCING INTO THE FORECAST AREA FROM THE WEST AND
SOUTH. WILL HAVE POPS INCREASE FROM CHANCE IN THE MORNING TO LIKELY
POPS IN THE WEST WITH CHANCE POPS OVER THE CENTRAL AND NORTHERN
ZONES.

TEMPS TONIGHT WILL BENEFIT FROM THE OVERCAST SKIES WITH LOWS IN THE
LOWER 40S OVER MOST OF REGION...THEN UPPER 30S FOR THE EASTERN LAKE
ONTARIO REGION. HIGHS ON WEDNESDAY WILL REBOUND TO UPPER 40S TO LOW
50S.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
THIS PERIOD BEGINS WITH A SHOWER THREAT AS AN INITIAL UPPER LEVEL
SHORT WAVE SLIDES TO OUR NORTH AND WEST. PRECIPITATION POTENTIAL
WILL DIMINISH LATER WEDNESDAY NIGHT AS THIS FEATURE LIFTS NORTHEAST
AND A DRY SLOT BUILDS INTO THE AREA AHEAD OF THE NEXT SYSTEM WHICH
LOOKS TO COMPLICATE MATTERS FROM LATE THANKSGIVING DAY THROUGH
FRIDAY. TURKEY DAY SHOULD START OUT DRY AND RELATIVELY MILD WITH
TEMPS IN 45-50 RANGE FOR MORNING ACTIVITIES.

THE MAIN FORECAST CONCERN WILL BE FOR THE PERIOD THURSDAY NIGHT
THROUGH FRIDAY NIGHT. MODELS HAVE BEEN ADVERTISING A COMPLICATED
SCENARIO FOR SEVERAL DAYS NOW...BUT THE 12Z RUNS HAVE NOW COME INTO
PRETTY GOOD CONSENSUS. THE MAIN CHANGE FROM YESTERDAY IS THE LACK OF
PHASING OF THE NORTHERN AND SOUTHERN STREAMS...THEREBY NEGATING THE
POTENTIAL OF A BOMB TYPE STORM OVER NEW ENG OR EASTERN NY.
RATHER...WE WILL BE DEALING WITH A STEEPENING UPPER TROF JUST TO OUR
WEST THURSDAY AFTERNOON...CLOSING OFF INTO AN UPPER LOW OVER LK ERIE
OR NORTHERN OHIO (NAM FURTHEST NORTH, GFS FURTHEST SOUTH) BY 06Z FRI.
THIS FEATURE SPAWNS A SFC LOW OVER CNTRL PA WHICH WILL LIFT UP INTO
SE NY FRI AFTERNOON AS UPPER LOW PUSHES EAST ACROSS NRN PA. THE LOW
EVENTUALLY DEEPENS BUT NOT UNTIL IT GETS OFF THE NEW ENG COAST FRI
NT.

ASSUMING THIS SCENARIO PLAYS OUT...WESTERN AND CNTRL NY WILL GET OFF
FAIRLY EASY AS BEST DYNAMICS WILL BE JUST SOUTH OF THE UPPER LOW AND
WE WILL JUST NORTH OF THIS FEATURE. THERE WILL BE AN INITIAL SHOT OF
RAIN....PERHAPS 0.25 INCH OR SO...PUSHING INTO WESTERN AREAS THURS
AFTERNOON AND REACHING CNTRL NY THURS EVE. COLDER AIR WILL ADVECT IN
FROM THE SOUTHWEST AS THE UPPER LOW PASSES EAST LATER THURS
NT...WITH 850 MB DROPPING TO -5C OR SO ALONG NY-PA BORDER OF WESTERN
SRN TIER. THUS SHOULD BE COLD ENOUGH TO CHANGE RAIN TO SNOW OVER
HIGHER ELEVS...BUT MOST OF MOISTURE WILL BE STRIPPED AWAY BY 12Z
FRI. CANT RULE OUT EVEN SOME WET FLAKES AS FAR NORTH AS BUF AREA BUT
ANY ACCUMS HERE UNLIKELY.

FRIDAY WILL BE A RAW CHILLY DAY WITH SOME RAIN/WET SNOW IN THE
AIR...BUT QPF LOOKS QUITE LIGHT...UNDER 0.1 INCH. BOTH 12Z ECMWF AND
GFS NOW KEEP BULK OF PRECIP E OF GENESEE VALLEY BY MIDDAY SO WEST
WILL BE GENERALLY DRY IN AFTERNOON. PCPN COULD BE IN THE FORM OF WET
SNOW IN AM ACROSS SOUTHERN AREAS...BUT MILDER AIR AT 850 MB WILL BE
WRAPPING AROUND THE SYSTEM FROM THE EAST WITH AREAS CLOSER TO LK
ONTARIO RISING FROM -4C TO -1C DURING THE DAY...SO ANYTHING WOULD BE
LIQUID AT LOWER ELEVS AND E OF LK ONTARIO.

MODELS PULL SYSTEM EAST A BIT FASTER THAN IN PREVIOUS RUNS...
ESPECIALLY GFS WHICH BUILDS A SFC RIDGE ACROSS AREA ON SATURDAY.
ECMWF A BIT SLOWER. WILL SPEED UP CLEARING BY ABOUT 6 HOURS...
KEEPING UPSLOPE PCPN SE OF LAKES FRI NT BUT LITTLE OR NONE
ELSEWHERE. WE DO NOT GET ESPECIALLY COLD AFTER THIS SYSTEM EVEN WITH
A BRISK NW WIND FRI NT...JUST NOT ENOUGH COLD AIR TO TAP...WITH 850
MB TEMPS BOTTOMING OUT AROUND -6C...PROBABLY TOO MILD FOR ANY REAL
ACCUMULATING SNOW...EVEN AT HIGHER ELEVS...WITH LOW ELEVS MAINLY
LIQUID.

SUMMING UP...SNOW POTENTIAL FOR THIS SYSTEM WOULD BE IN THE 1-3
INCH RANGE ACROSS SRN TIER...MAINLY HIGHER ELEVS...THURS NT/FRI
AM...AND PERHAPS ANOTHER INCH OR TWO IN UPSLOPE AREAS SE OF LK ERIE
AND SIMILAR AMTS ON TUG HILL FRI NT/SAT AM. LITTLE OR NOTHING
ELSEWHERE.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS NOTED ABOVE...MODELS CLEARING SYSTEM OUT QUICKLY BY SATURDAY...
WITH GFS SHOWING A SFC RIDGE OVER AREA SATURDAY WHILE ECMWF A BIT
SLOWER AND HOLDING IT OFF UNTIL SAT NT. IN ANY CASE...WILL MAINTAIN
CHC POPS SE OF THE LAKES...AND CONTINUE INTO SAT EVE SE OF LK
ONTARIO. P-TYPE DEPENDENT ON ELEVATIONS BUT DO NOT EXPECT ANY
ACCUMS. MAINLY DRY ELSEWHERE SAT BUT CHILLY WITH MAXES IN L40S AS
850MB TROF (-5C) SWINGS THROUGH.

SUNDAY LOOKS PLEASANT AS RIDGING BUILDS IN AT ALL LEVELS. 850 MB
TEMPS SOAR TO +5C WHICH WOULD SUPPORT NR 50 WITH ANY SUN...ALWAYS A
QUESTION THIS TIME OF YEAR...BUT A DECENT DAY NONETHELESS. NEXT
SYSTEM DEEPENS OVER CENTRAL STATES MONDAY AND SLOWLY MOVES
EAST...WILL INCR CHC OF SHOWERS HERE MON AFTERNOON AS THIS FEATURE
APPROACHES AND CONTINUE THEM THROUGH TUESDAY. SHOULD BE QUITE MILD
MON AND COLDER TUES. CONFIDENCE LOW IN DETAILS AS MODELS CONTINUE TO
BUCKLE TROFS AND CLOSE THEM OFF BUT NONE HAVE BEEN ABLE TO YANK ON
ANY ARCTIC AIR AND IT DOESNT LOOK LIKE ANY WILL...AT LEAST THROUGH
THE MIDDLE OF NEXT WEEK.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
BUF/IAG/ROC...FEEL FAIRLY CONFIDENT THAT DRIZZLE WILL BECOME LESS
OF AN ISSUE THIS EVENING...WITH LOW CIGS/VSBY ASSOCIATED WITH THIS
LOW MOISTURE DIMINISHING THROUGH THE EVENING HOURS. BASED ON BOTH
NAM/GFS BUFKIT DATA...FEEL CIGS WILL SCATTER OUT ROUGHLY
06Z...THOUGH THIS IS DIFFICULT TO TIME. THIS WILL ALLOW TEMPS TO
DROP NEAR THE SURFACE...WITH SOUTHERLY WINDS PICKING UP TOWARDS
DAY BREAK. AT THIS POINT...CAN SEE THIS RESULTING IN PERIODIC CIGS
BELOW THE INVERSION (AROUND 1000 FT)...LIGHT FOG...OR NO
RESTRICTION AT ALL. HEDGE TAFS ON THE OPTIMISTIC SIDE...THOUGH
HAVE VERY LOW CONFIDENCE BETWEEN 06Z - 12Z FOR THESE SITES...WITH
VARIABLE CONDITIONS BETWEEN IFR AND VFR EXPECTED. ROUGHLY AFTER
12Z...EXPECT A VFR CIG TO SWEEP IN...WITH INCREASING CONFIDENCE IN
VFR CIGS. BAND OF -SHRA SPREADS IN BETWEEN 18Z AND 21Z. HEDGE MORE
OPTIMISTIC THAN MOS...BASED ON CLIMO WHICH SUGGESTS LOW CIGS ARE
NOT CLIMATOLOGICAL LY FAVORED IN A SOUTHERLY FLOW AT THESE SITES.

JHW...IR SATELLITE STARTING TO SUPPORT NAM BUFKIT...WITH BREAKS IN
CIGS EXPECTED TO DEVELOP LATE THIS EVENING. THIS WILL LIKELY NOT
LAST VERY LONG...WITH RADIATIONAL COOLING QUICKLY CAUSING EITHER
LOW CIGS OR FOG. TAF HITS LOW CIGS HARDEST...BUT MAY SEE A PERIOD
OF 1/2SM FG TONIGHT...EVEN THOUGH CIGS ARE EXPECTED TO BE THE MAIN
ISSUE SINCE WINDS WILL LIKELY LIMIT FOG DEVELOPMENT. CIGS SHOULD
BE SLOW TO RISE WEDNESDAY...WITH TIMING PROBLEMATIC...EVEN THOUGH
SLOW LIFTING TREND SEEMS SOLID.

ART...VFR CONDITIONS LIKELY THROUGH MUCH OF THE NIGHT...WITH
LOWERING OF CIGS (AND POSSIBLY FOG) AFTER MIDNIGHT.
BEYOND...LARGELY MVFR CONDITIONS THROUGH WEDNESDAY WITH -SHRA LATE.


OUTLOOK...
THURSDAY...VFR DETERIORATING TO MVFR/IFR WITH INCREASING CHANCES
OF RAIN.
FRIDAY...MVFR/IFR WITH RAIN LIKELY...MIXING WITH SNOW ACROSS THE
SOUTHERN TIER.
SATURDAY...MVFR WITH A CHANCE OF RAIN AND SNOW.

&&

.MARINE...
NO MARINE FLAGS WILL BE NEEDED FOR THE NEXT COUPLE OF DAYS. LIGHT TO
GENTLE EAST TO SOUTHEAST BREEZES ON THE LOWER LAKES TONIGHT WILL
RESULT IN LIMITED WAVE ACTION. SOUTH TO SOUTHWEST WINDS WILL
INCREASE AHEAD OF AN APPROACH LOW PUSHING INTO THE GREAT LAKES IN
THE WEDNESDAY THROUGH THURSDAY TIME FRAME...WITH CONDITIONS PROBABLY
REMAINING BELOW SMALL CRAFT LEVELS...ALTHOUGH WAVE HEIGHTS
APPROACHING 4 FEET ARE POSSIBLE ON LAKE ERIE WEDNESDAY NIGHT AND
EARLY THURSDAY. THE NEXT THREAT FOR MARINE FLAGS WILL LIKELY BE ON
FRIDAY AS A DEEPENING LOW PASSES UP TO OUR EAST. SMALL CRAFT
ADVISORIES WILL BE LIKELY DUE TO BRISK NORTHWESTERLIES FRIDAY
AFTERNOON AND SATURDAY.

&&

.CLIMATE...
STILL NO MEASURABLE SNOW SO FAR THIS SEASON OVER MOST OF WESTERN NY.
WE ARE ALREADY OVER TWO WEEKS LATE (NORMAL DATES ARE NOV 7 BUF AND
NOV 8 ROC). WE WILL AT LEAST GET TO FRIDAY (27TH) AND IF SO...WILL
BE LATEST IN 61 YRS (1948) AT BUF...AND LATEST IN 46 YRS (1963) AT
ROC. THE ALL TIME RECORD LATEST DATES FOR FIRST MEASURABLE SNOW ARE
DEC 3 1899 AT BUF AND DEC 10 1948 AT ROC. WE WILL NOT LIKELY REACH
THOSE DATES AS WX PATTERN LOOKS COLDER WITH SOME SNOW THREAT
BEGINNING LATER FRIDAY.

IN ADDITION, ITS BEEN A LONG TIME SINCE EITHER BUFFALO OR
ROCHESTER LAST SAW MEASURABLE SNOW. THROUGH TODAY, BUFFALO
HAS GONE 230 DAYS WITHOUT MEASURABLE SNOW, OR SINCE APRIL 7,
2009. THIS IS THE 6TH LONGEST STRETCH IN 125 YEARS OF RECORDS.
THE RECORD IS 277 DAYS SET BACK IN 1946. ROCHESTER IS ALSO AT 230
DAYS WITHOUT MEASURABLE SNOW, OR THE 6TH LONGEST STRETCH THERE. THE
RECORD IS 260 DAYS SET BACK IN 1952.

&&

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

&&

$$

SYNOPSIS...SFM
NEAR TERM...APFFEL/WCH
SHORT TERM...SFM
LONG TERM...SFM
AVIATION...APFFEL
MARINE...SFM/WCH
CLIMATE...







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