FXUS61 KBUF 070849
AFDBUF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
349 AM EST MON DEC 7 2009
.SYNOPSIS...
WEAK LOW PRESSURE WILL RIDE ALONG A STALLED FRONTAL BOUNDARY TO OUR
NORTH TODAY...AND THAT WILL RESULT IN A COUPLE INCHES OF SNOW
ACROSS THE NORTH COUNTRY. OUR ATTENTION WILL THEN TURN TO A
POWERFUL EARLY WINTER STORM SYSTEM THAT WILL IMPACT OUR REGION FROM
LATE TUESDAY NIGHT INTO FRIDAY. MIXED PRECIPITATION IN ADVANCE OF
THE STORM WILL CHANGE TO RAIN WEDNESDAY WITH VERY STRONG WINDS
DEVELOPING. THE STRONG WINDS WILL THEN BE ACCOMPANIED BY LOWER
TEMPERATURES AND WIDESPREAD LAKE EFFECT SNOW SHOWERS.
&&
.NEAR TERM /THROUGH TONIGHT/...
LAKE SNOW AND CLOUDS OFF LAKE ERIE HAVE DISSIPATED AS LOW LEVEL
WINDS BACKED TO A MORE SOUTHERLY DIRECTION AHEAD OF THE NEXT SHORT
WAVE TO AFFECT THE REGION. WILL SEE LAKE SNOWS OFF LAKE ONTARIO TO
PERSIST FOR A FEW MORE HOURS THIS EARLY MORNING...THEN BE
ASSIMILATED INTO A BAND OF SNOW FORMING ALONG THE NORTHERN SHORE OF
THE LAKE. EXPECT THIS WARM ADVECTION BAND OF SNOW TO AFFECT THE
NORTH COUNTY THROUGH THE AFTERNOON AND EVENING WITH AN ACCUMULATION
OF OF 1 TO 3 INCHES WITHIN THE 3 EASTERN LAKE ONTARIO COUNTIES. SOME
TERRAIN ENHANCED LIFT OVER THE SOUTHERN TIER WILL ALSO PRODUCE 1 TO
2 INCHES OF SNOW...WITH AN INCH OR LESS ELSEWHERE. WILL HAVE LIKELY
POPS FOR THE EASTERN LAKE ONTARIO AND SOUTHERN TIER AREAS...AND
CHANCE POPS FOR THE REST OF THE FORECAST AREA.
THE SURFACE LOW WILL FADE AS IT MOVES INTO NEW ENGLAND TONIGHT...BUT
THE LINGERING COLDER AIR TRAILING THE LOW WILL AGAIN BRING SOME LAKE
EFFECT. LAKE SNOW TO THE EAST OF LAKES ERIE AND ONTARIO WILL AGAIN
SET UP AFTER MIDNIGHT WITH LIKELY POPS IN THESE AREAS. SNOW
ACCUMULATIONS WILL BE IN THE 1 TO 2 INCH RANGE...POSSIBLY 3 INCHES
ON THE HIGHEST HILLS OF THE CHAUTAUQUA RIDGE AND ON THE TUG HILL
PLATEAU.
TEMPS TODAY WILL BE IN THE LOWER TO MID 30S AND LOWS TONIGHT WILL
SETTLE TO A RATHER UNIFORM COVERAGE OF MIDDLE 20S.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
TUESDAY WILL ESSENTIALLY BE THE 'CALM BEFORE THE STORM' AS A H5
RIDGING WILL BUILD ACROSS THE GREAT LAKES REGION WHILE A STRONG
SHORTWAVE WILL MAKE ITS WAY OUT OF THE ROCKIES. AT THE SFC...HIGH
WILL DRIFT ACROSS OUR REGION IN THE PROCESS.
WHILE THE BULK OF WESTERN AND NORTH CENTRAL NEW YORK WILL
EXPERIENCE FAIR WEATHER ON TUESDAY...H85 TEMPS OF -9C WILL KEEP
SOME LAKE EFFECT SNOW SHOWERS OVER OSWEGO COUNTY. HAVE BUMPED POPS
TO LIKELY IN THIS AREA FOR THE MORNING HOURS...BUT DURING THE
COURSE OF THE DAY...DRIER MID LEVEL AIR AND WARMING ALOFT WILL
BRING AN END TO THE ACTIVITY. FRESH ACCUMS FOR OSWEGO CO ON
TUESDAY SHOULD BE AN INCH OR LESS.
IT WILL START TO BECOME VERY INTERESTING TUESDAY NIGHT AS A STRONG
SHORTWAVE WILL CROSS THE MISSISSIPPI VALLEY AND MID WEST. THE SFC
REFLECTION OF THIS SHORTWAVE...IN THE FORM OF A POWERFUL EARLY
WINTER STORM...WILL MOVE NORTHEAST FROM OKLAHOMA TO NEAR CHICAGO.
BOTH THE GFS AND ECMWF ARE VERY SIMILAR IN THEIR SOLUTIONS...WITH A
CENTRAL PRESSURE DEEPENING TO ARND 980MB BY DAYBREAK.
A MOISTURE RICH SOUTHERLY FLOW (60KT LL JET) WILL DEVELOP ACROSS OUR
WESTERN COUNTIES IN ADVANCE OF THE STORM SYSTEM TUESDAY NIGHT. THE
DEEPENING MOISTURE FIELD WILL COMBINE WITH SEVERAL SOURCES OF LIFT
TO GENERATE WIDESPREAD SNOW AS TUESDAY NIGHT PROGRESSES. THE THREE
MAIN SOURCES OF LIFT WILL INCLUDE ISENTROPIC LIFT FROM THE
WAA...DIFFLUENT FLOW ALOFT AND A COUPLED H25 150KT JET.
WIDESPREAD SNOW WILL BREAK OUT ACROSS THE WESTERN COUNTIES BY
MIDNIGHT WITH THE SNOW GRADUALLY SPREADING NORTH AND EAST ACROSS THE
NORTH COUNTRY. GFS POINT SOUNDINGS...WHILE WARMER THAN YESTERDAYS
RUNS...ARE STILL SUGGESTING THAT THE PCPN WILL BE IN THE FORM OF
SNOW AT THE ONSET FOR ALL SITES. THE SNOW WILL THEN MIX WITH A
CHANGE TO SLEET AND FREEZING RAIN OVER MUCH OF THE WRN SOUTHERN TIER
BY DAYBREAK WEDNESDAY. THE TIMING OF THIS CHANGEOVER WILL BE
IMPORTANT AS TO HOW MUCH SNOW ACCUMULATES. EARLY ESTIMATES FOR
SNOWFALL TUESDAY NIGHT WILL GENERALLY BE 2 INCHES OR LESS...BUT A
SLOWER CHANGEOVER COULD EASILY TRANSLATE INTO ADVISORY CRITERIA
SNOWFALL AMOUNTS.
THE NEWLY PHASED STORM WILL THEN TRACK FROM CHICAGO TO GEORGIAN BAY
ON WEDNESDAY WHILE FURTHER DEPEENING TO ABOUT 975MB. AGAIN...THE GFS
AND ECMWF ARE REMARKABLY SIMILAR IN THEIR SOLUTIONS. THE 975MB CENT
PRESSURE WILL BE SOME 3 TO 4 STANDARD DEVIATIONS BELOW NORMAL MID
DECEMBER VALUES...WHICH IS AN EASY CLUE TO A SIGNIFICANT WEATHER
EVENT. IN ANY CASE...THE TRACK OF THIS PWERFUL STORM TO OUR WEST
WILL RESULT IN STRONG WARM ADVECTION ACROSS ALL OF OUR REGION. THIS
WILL CHANGE ALL OF THE WINTRY PCPN TO RAIN WEDNESDAY AS H85 TEMPS
WILL PEAK AT ABOUT +5C.
THE PASSAGE OF A COLD FRONT LATE WEDNESDAY AFTERNOON WILL THEN USHER
THE RETURN OF COLD AIR TO THE REGION...PARTICULARLY THE WRN COUNTIES
WHERE THE RAIN WILL CHANGE BACK TO SNOW BY EVENING. MORE IMPORTANTLY
THE SFC WINDS WILL PICK UP WITHIN THE CYCLONIC COLD ADVECTIVE
PATTERN WITH WINDS INCREASING TO 25 TO 40 MPH WEDNESDAY EVENING WITH
ADDITIONAL STRENTHENING OF THE WINDS DURING THE COURSE OF WEDNESDAY
NIGHT.
THE DEEP LOW WILL LIFT NORTHEAST TO WESTERN QUEBEC WEDNESDAY NIGHT.
THIS WILL PLACE OUR REGION ON THE BACKSIDE OF A TIGHTLY WOUND WINTER
STORM WITH MUCH COLDER AIR CHARGING INTO OUR AREA ON STRONG WESTERLY
WINDS. THESE WINDS WILL BE AT LEAST ADVISORY CRITERIA LEVELS WITH
THE POTENTIAL FOR WARNING CRITERIA TO BE MET. AS MENTIONED IN
PREVIOUS DISCUSSIONS THOUGH...AN IMPORTANT INGREDIENT MISSING FOR A
CLASSIC HIGH WIND EVENT IS THE STRONG WINDS ALOFT. WINDS WILL ONLY
AVERAGE 50 KNOTS BETWEEN 3-8K FT...BUT THESE WILL STILL BE STRONG
ENOUGH TO CAUSE PROBLEMS.
H85 TEMPS WILL DROP TO -10C WEDNESDAY NIGHT...AND THIS WILL SET UP
STEEP LAPSE RATES IN THE LOWEST 8K FT OR SO OF THE BOUNDARY LAYER
OVER THE LAKES. THIS WILL ALLOW LAKE SNOWS TO DEVELOP EAST OF BOTH
LAKES...BUT DUE TO THE VERY STRONG WINDS...THE SNOW BANDS WILL NOT
BE AS CONCENTRATED OR INTENSE AS THEY WOULD OTHERWISE BE. THEY WILL
ALSO EXTEND FURTHER INLAND. WHILE THE BANDS COULD INITIALLY SET UP
OVER THE BUF AND ART METRO AREAS DURING THE FIRST HALF OF WEDNESDAY
NIGHT...THE BANDS ARE EXPECTED TO SETTLE TO THE SOUTH AS THE FLOW
VEERS TO A MORE WESTERLY FETCH.
THE DEEP LOW WILL CONTINUE TO LIFT AWAY FRO THE REGION ON THURSDAY
AS IT WILL TRACK ACROSS SOUTHERN QUEBEC. A TIGHT PRESSURE GRADIENT
WILL REMAIN IN PLACE OVER OUR REGION WITH 3-5MB/3HR ISALLOBARIC
PRESSURE RISES FORECAST. THIS WILL MAKE THURSDAY A VERY WINDY
DAY...AND WITH H85 TEMPS FALLING TO -15C...THERE WILL BE WIDESPREAD
WIND SWEPT LAKE EFFECT SNOW SHOWERS. THE STRONG WINDS WILL GREATLY
LIMIT THE RESIDENCY TIME FOR THE AIR OVER THE LAKES...SO ACCUMS BOTH
WED NIGHT AND THURSDAY WILL LIKELY BE LIMITED. EVEN SO...THE VERY
STRONG WINDS AND WIDESPREAD LAKE SNOW SHOWERS WILL COMBINE TO
PRODUCE TIMES OF VERY POOR VISIBILITY. IN FACT...BLIZZARD LIKE
CONDITIONS MAY BE EXPERIENCED AT TIMES.
WHILE SNOWFALL WILL LIKELY BE HELD IN CHECK BY THE STRONG WINDS...
BOTH THE GFS AND ECMWF SUGGEST A STRONG MULTI-LAKE CONNECTION FROM
LAKE SUPERIOR AND HURON...ACROSS LAKE ONTARIO. THIS WELL PRIMED BAND
COULD THUS BE MUCH MORE EFFICIENT AND PERFORM TO A MORE IMPRESSIVE
LEVEL THAN ITS LAKE ERIE COUNTERPART. THIS WILL PUT OSWEGO COUNTY
AND THE TUG HILL REGION WITHIN THE CROSS HAIRS FOR WHAT COULD PROVE
TO BE DANGEROUS CONDITIONS LATER THURSDAY INTO THURSDAY NIGHT AS H85
TEMPS CONTINUE TO PLUMMET TO BETWEEN -16 AND -20C.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
THE BROAD BASED ARCTIC LIKE TROUGH OVER THE GREAT LAKES WILL SLOWLY
LIFT OUT ON FRIDAY...BUT -16 TO -20C AIR WILL CONTINUE TO POUR
ACROSS THE WIDE OPEN LAKES TO PRODUCE SCT LAKE SNOW SHOWERS.
ACCUMUALTING LAKE SNOWS WILL CONTINUE EAST OF BOTH LAKES IN THE
TYPICAL SNOWBELTS.
THE TROUGH WILL CONTINUE TO LIFT ON SATURDAY WHILE HIGH PRESSURE
WILL WORK NORTHWARDS FROM THE OHIO VALLEY. THIS WILL HELP TO LOWER
THE EQUILIBRIUM LEVEL...AT LEAST ON LAKE ERIE...SO THE LAKE SNOWS
SHOULD START TO DIMINISH IN INTENSITY AND COVERAGE. TEMPS WILL
REMAIN WELL BELOW NORMAL THOUGH....WITH HIGHS IN MOST AREAS STAYING
BELOW FREEZING.
A MID LEVEL RIDGE WILL THEN BUILD ACROSS THE LOWER GREAT LAKES
SATURDAY NIGHT AND SUNDAY. THIS WILL FURTHER DIMINISH THE LAKE SNOW
SHOWERS WITH JUST FLURRIES EXPECTED FOR THE REGION BY SUNDAY
AFTERNOON.
THE STRETCH OF BELOW NORMAL TEMPERATURES WILL THEN FINALLY BREAK
DOWN EARLY NEXT WEEK...AS THE CROSS-POLAR FLOW FROM THE YUKON WILL
BECOME MORE PACIFIC IN ORIGIN.
&&
.AVIATION /09Z 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...
SMALL CRAFT ADVSIORIES HAVE EITHER EXPIRED OR HAVE BEEN CANCELLED
FOR ALL OF THE NY NEARSHORE WATERS THIS MORNING AS HIGH PRESSURE TO
OUR SOUTH HAS RESULTED IN A MORE RELAXED PRESSURE GRADIENT.
A WEAK PRESSURE GRADIENT WILL THEN BE FOUND OVER LAKES ERIE AND
ONTARIO TONIGHT THROUGH TUESDAY AS HIGH PRESSURE WILL DRIFT ACROSS
THE REGION. THESE TRANQUIL CONDITIONS WILL QUICKLY GIVE WAY TO VERY
STRONG WINDS LATER TUESDAY NIGHT THROUGH AT LEAST THURSDAY NIGHT AS
A POWERFUL EARLY WINTER STORM WILL LIFT ACROSS THE GREAT LAKES
REGION.
WINDS IN THE WAKE OF THE DEEP STORM SYSTEM WILL REACH AT LEAST HIGH
END GALES WEDNESDAY NIGHT AND THURSDAY...WITH THE LIKELIHOOD OF
STORM FORCE GUSTS.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...RSH
NEAR TERM...WCH
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...JJP/JJR
MARINE...RSH
