FXUS61 KBUF 081551
AFDBUF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1051 AM EST TUE DEC 8 2009
.SYNOPSIS...
TODAY WILL ESSENTIALLY BE THE CALM BEFORE THE STORM AS HIGH PRESSURE
WILL DRIFT ACROSS THE REGION. A DEEPENING AREA OF LOW PRESSURE WILL
LIFT OUT OF THE PLAINS TONIGHT WITH SNOW SPREADING ACROSS THE
REGION FROM THE SOUTHWEST DURING THE COURSE OF THE NIGHT. A MIXED
BAG OF PRECIPITATION ON WEDNESDAY WILL THEN GIVE WAY TO VERY WINDY
AND MUCH COLDER CONDITIONS WEDNESDAY NIGHT AND THURSDAY AS THE
POWERFUL STORM SYSTEM WILL LIFT ACROSS EASTERN CANADA.
&&
.NEAR TERM /THROUGH TONIGHT/...
LIGHT LAKE EFFECT SNOW SHOWERS AND FLURRIES ARE IN THE PROCESS OF
DYING ACROSS THE LOWER LAKES LATE THIS MORNING. OFF LAKE ERIE...
SCATTERED FLURRIES EXTEND INLAND ACROSS THE NORTHERN HALF OF
CHAUTAUQUA/CATTARAUGUS COUNTIES WITH A TEA KETTLE BAND JUST OFFSHORE
FROM DUNKIRK TO SILVER CREEK. EXPECT THIS ACTIVITY TO LINGER THROUGH
EARLY AFTERNOON BEFORE ENDING ALTOGETHER. OFF LAKE ONTARIO REGIONAL
RADAR SUGGESTS LAKE EFFECT FLURRIES HAVE ENDED.
OTHERWISE...LAKE EFFECT CLOUDS WILL HANG ON ALONG THE SOUTH SHORE OF
LAKE ONTARIO AND ALSO ACROSS THE WESTERN SOUTHERN TIER THROUGH EARLY
TO MID AFTERNOON. BY THE TIME THIS CLOUD COVER BEGINS TO BREAK DOWN
MID LEVEL CLOUD FROM THE NEXT STORM SYSTEM WILL BE OVERSPREADING THE
AREA...SO EXPECT THESE AREAS TO AVERAGE MOSTLY CLOUDY FOR THE DAY. A
NARROW WINDOW OF CLEARING FROM BUFFALO/NIAGARA TO GENESEE COUNTY
WILL BRING SOME SUN TO THESE AREAS THROUGH EARLY AFTERNOON BEFORE
THE MID CLOUD INCREASES. THE NORTH COUNTRY WILL BE MOSTLY SUNNY
TODAY. HIGHS QUITE SEASONABLE WITH MID 30S ACROSS THE LOWER
ELEVATIONS AND AROUND 30 ACROSS HIGHER TERRAIN.
THE NIGHT WILL START ON A QUIET NOTE...THEN CONDITIONS WILL
DETERIORATE OVERNIGHT...ESPECIALLY OVER THE WESTERN COUNTIES. LOW
PRESSURE MOVING RAPIDLY FROM THE MIDDLE PLAINS WILL DEEPEN AS IT
REACHES THE SOUTHERN END OF LAKE MICHIGAN BY DAYBREAK. A STRONG
850MB LOW LEVEL JET AHEAD OF THIS DEEPENING LOW WILL INCREASE TO
NEAR 80 KNOTS OVER THE WESTERN SOUTHERN TIER BY 12Z /7AM/ WED...WITH
SUSTAINED SURFACE WINDS INCREASING TO A RANGE OF 25 TO 35 MPH.
WINDS VERY LATE TONIGHT ARE EXPECTED TO GUST ABOVE 50 MPH ACROSS THE
WESTERN COUNTIES...ESPECIALLY ON THE HILLS OF THE SOUTHERN TIER INTO
WYOMING AND SOUTHERN ERIE COUNTIES...BETWEEN 5AM AND DAYBREAK...AND
BECOMING MORE WIDESPREAD DURING THE DAY ON WEDNESDAY.
PRECIP SPREADING IN FROM THE SOUTHWEST WILL INCREASE AFTER
MIDNIGHT...IN THE FORM OF SNOW...THEN MIXING WITH SLEET AFTER 3AM AS
850MB TEMPS CLIMB ABOVE FREEZING OVER THE WESTERN SOUTHERN TIER AND
THE NIAGARA FRONTIER. WIND DRIVEN SNOW AND SLEET WILL LIKELY PRODUCE
MAJOR PROBLEMS DURING THE MORNING COMMUTE FOR MUCH OF THE WESTERN NY
COMMUNITIES...INCLUDING ALL OF THE BUFFALO AND NIAGARA FALLS METRO
AREAS.
WIDESPREAD SNOW WILL FALL OVER MUCH OF THE REST OF THE
FORECAST AREA WITH OVERNIGHT SNOW ACCUMULATIONS AROUND 3 INCHES
ALONG THE GENESEE VALLEY AND WESTERN FINGER LAKES. THE EASTERN LAKE
ONTARIO REGION WILL SEE THE SNOW LATE AT NIGHT AND INCREASING DURING
THE MORNING ON WEDNESDAY.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
IT WILL BE QUITE STORMY THROUGH THIS PERIOD AS AN ANOMALOUSLY DEEP
AREA OF LOW PRESSURE WILL TRACK TO OUR WEST AND NORTH. THE PERIOD
WILL FEATURE A MIXED BAG OF PRECIPITATION TO START...THEN IT WILL
EVOLVE INTO A HIGH WIND EVENT WITH WIND DRIVEN LAKE SNOWS SETTING
UP. THE IMPACT OF THIS WEATHER WILL LIKELY BE SIGNIFICANT FOR PUBLIC
DECISIONS...SO IT WILL BE IMPORTANT TO STAY TUNED AS THE SCENARIO
UNFOLDS.
THE MAIN IMPACT DURING THE PERIOD WILL BE THE VERY STRONG WINDS. A
HIGH WIND WATCH WILL BE ISSUED WITH THIS PACKAGE FOR ALL OF WESTERN
AND NORTH CENTRAL NEW YORK. THE WATCH WILL COVER THE PERIOD FROM
WEDNESDAY EVENING THROUGH EARLY THURSDAY NIGHT...ALTHOUGH IT WILL
BEGIN WEDNESDAY MORNING FOR THE WESTERN SOUTHERN (SEE BELOW. A SUB
980 MB LOW WILL TRACK FROM CHICAGO WEDNESDAY MORNING TO GEORGIAN BAY
BY WEDNESDAY EVENING...THEN TO WESTERN QUEBEC BY THURSDAY MORNING
AND THE MOUTH OF THE ST LAWRENCE THURSDAY EVENING. THIS IS A VERY
FAVORABLE STORM TRACK FOR STRONG WINDS FOR THE REGION...PARTICULARLY
FROM LAKE ERIE AND THE NIAGARA FRONTIER TO ROCHESTER AND THE LOWER
GENESEE VALLEY.
THE CENTRAL PRESSURE OF THE POWERFUL STORM SYSTEM WILL BE SOME 4
STANDARD DEVIATIONS BELOW 'NORMAL' MID DECEMBER STORMS. THAT NUMBER
MAY MEAN SOMETHING TO SOME METEOROLOGISTS...BUT A BETTER WAY OF
THINKING ABOUT IT IS THAT CLIMATOLOGICALLY...A STORM OF THIS
MAGNITUDE ONLY HAS A 0.3 PERCENT CHANCE OF FORMING ON THE AFFECTED
DATES. THAT IS LESS THAN HALF OF A PERCENT CHANCE!
BACK TO THE WIND THREAT. A 60-70 KT LOW LEVEL JET (6K FT) WILL RACE
NORTHWARDS ACROSS WESTERN NEW YORK WEDNESDAY MORNING AS THE STORM
SYSTEM WILL LIFT ACROSS THE CENTRAL GREAT LAKES. THE BULK OF THESE
WINDS WILL BE HELD ABOVE AN INVERSION AT 4K FT...BUT WINDS OF 30-40
MPH WILL BE POSSIBLE ACROSS THE HIGHER TERRAIN DURING THE DAY. THE
HIGH WIND WATCH WILL START EARLIER IN THIS AREA BECAUSE OF THIS
ELEVATED WIND THREAT. THE REAL WIND THREAT THOUGH WILL BE FOUND
WEDNESDAY NIGHT THROUGH THURSDAY.
A COLD FRONT WILL PLOW ACROSS THE REGION WEDNESDAY AFTERNOON WITH
STRONG COLD ADVECTION IN ITS WAKE. A VERY TIGHT SFC PRESSURE
GRADIENT WILL THEN COMBINE WITH WELL ALIGNED (3-10K FT) 50-60KT
WINDS ALOFT AND 3-5MB/3HR ISALLOBARIC RISES TO PRODUCE VERY STRONG
WINDS ACROSS THE REGION LATE WEDNESDAY THROUGH THURSDAY. THIS WILL
LIKELY RESULT IN SUSTAINED SFC WINDS IN THE VICINITY OF 25 TO 40 MPH
WITH GUSTS OVER 60 MPH. AS MENTIONED...THE STRONGEST WINDS SHOULD BE
FOUND FROM LK ERIE AND THE IAG FRONTIER TO ROCHESTER WHERE THE
IMPACT WILL BE THE GREATEST. THESE STRONG WINDS WILL VERY SLOWLY
SUBSIDE DURING THE COURSE OF THURSDAY NIGHT AND FRIDAY.
SINCE THERE WILL BE A PROLONGED PERIOD OF VERY STRONG SOUTHWEST
WINDS WEDNESDAY NIGHT AND THURSDAY...THE POTENTIAL FOR LAKE SHORE
FLOODING FROM HAMBURG TO BUFFALO WILL HAVE TO BE MONITORED CLOSELY
AS WELL.
THE WINDS WILL NOT BE THE ONLY PROBLEM TO DEAL WITH DURING THIS
PERIOD. SNOW WILL INITIALLY BE FOUND ACROSS THE REGION WEDNESDAY
MORNING AS THE POINT SOUNDINGS SHOW THAT THE AIRMASS WILL REMAIN
BELOW FREEZING UNTIL LATER IN THE MORNING...OR IN THE CASE OF THE
EASTERN LAKE ONTARIO REGION...THE MIDDAY HOURS. A COUPLE INCHES OF
WET SNOW COULD FALL WEDNESDAY MORNING BEFORE THE CHANGEOVER TO SLEET
AND RAIN WILL TAKE PLACE. DEPENDING ON THE TIMING OF THE CHANGE OVER
AND THE AMOUNT OF MIXED WINTRY PCPN...THIS COULD WARRANT A SHORT
LIVED WINTER WEATHER ADVISORY.
THE PCPN WILL THEN CHANGE BACK TO A WINTRY MIX OF SLEET AND SNOW
FROM WEST TO EAST LATER IN THE AFTERNOON AS THE COLD AIR WILL DEEPEN
IN THE WAKE OF THE COLD FRONT. POINT SOUNDINGS SUGGEST A LACK OF A
DENDRITIC SNOW GROWTH REGION FOR SEVERAL HOURS AFTER FROPA SO THERE
COULD BE A PERIOD OF MISTY RAIN AND OR SLEET BEFORE THE COLD AIR
BECOMES DEEP ENOUGH FOR JUST SNOW.
THE COLD AIR WILL RAPIDLY DEEPEN DURING THE COURSE OF WEDNESDAY
NIGHT AS H85 TEMPS WILL DROP TO -6/-8C BY ABOUT MIDNIGHT AND -10/12C
BY DAYBREAK THURSDAY. THE COLD AIR WILL SET OF LAPSE RATES OF
8-10 DEG C/KM IN THE LOWEST 5K FT OVER THE LAKES...WITH LAKE INDUCED
CAPES AVG 300-500J/KG AND AN EQUILIBRIUM LEVEL OF ABOUT 11K FT.
WHILE THESE VALUES COULD NORMALLY BE SOMEWHAT IMPRESSIVE...THE VERY
STRONG WIND FIELDS WILL ACTUALLY BE COUNTER-PRODUCTIVE TO HEAVY
SNOWFALL RATES/PLUME CONCENTRATIONS.
RATHER...THE LAKE SNOW BANDS WILL LIKELY BE MORE DIFFUSE AS THEY
MOVE AWAY FROM THE LAKE AND WILL EXTEND FURTHER INLAND. WHILE
SNOWFALL RATES WILL LIKELY BE SOMEWHAT SUPPRESSED...THE WIND SWEPT
LAKE SNOWS WILL RESULT IN WIDESPREAD AREAS OF NEAR BLIZZARD
CONDITIONS. THIS WILL ESPECIALLY BE THE CASE ACROSS THE WRN SOUTHERN
TIER AND OVER THE TUG HILL AREA EAST OF LK ONTARIO. IT IS ALSO
POSSIBLE THAT THE HIGHER SNOW ACCUMS WILL BE FOUND FURTHER INLAND
THAT USUAL. IN ANY CASE...WEDNESDAY NIGHT AND THURSDAY SHOULD PROVE
QUITE CHALLENGING FOR THOSE THAT MAY HAVE TO TRAVEL THROUGH THOSE
AREAS.
THE COLD AIR WILL CONTINUE TO DEEPEN ACROSS THE EASTERN GREAT LAKES
THURSDAY AND FRIDAY AS H85 TEMPS WILL SETTLE TO BETWEEN -16 AND
-20C. THE PERSISTENT WESTERLY FLOW OF THIS VERY COLD AIRMASS OVER
THE WIDE OPEN LAKES WILL KEEP PERSISTENT LAKE SNOWS OVER THE WRN
SOUTHERN TIER AND OVER THE TUG HILL REGION WHILE STRONG WINDS WILL
CONTINUE TO PRODUCE WHITE OUT CONDITIONS IN THE VCNTY OF THE BANDS.
THE ACTIVITY EAST OF LAKE ONTARIO SHOULD BE STRONGER THAN ITS LK
ERIE COUNETRPART DURING THIS PERIOD...AS THE BROAD CYCLONIC FLOW
WILL ENCOURAGE MULTI-LAKE PRIMING FROM LAKE SUPERIOR AND GEORGIAN
BAY.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
TEMPERATURES WILL CLEARLY REMAIN BELOW NORMAL DURING THIS PERIOD AS
A COLD WESTERLY FLOW WILL GENERALLY REMAIN IN PLACE. THIS WILL KEEP
A STEADY FEED OF -12 TO -16C H85 OVER OUR REGION.
FOR SATURDAY...THE DEEP TROUGH WILL HAVE LIFTED OUT ACROSS EASTERN
QUEBEC BUT ANOTHER VIGOROUS SHORTWAVE WILL BE MOVING ACROSS THE FAR
REACHES OF WRN ONTARIO. IN BETWEEN...SFC BASED HIGH PRESSURE OVER
THE MIDDLE ATLANTIC STATES WILL LIKELY DISRUPT THE SNOW BANDS THAT
WILL BE IN PLACE DURING THE MORNING. THIS SHOULD ALLOW FOR THE BULK
OF THE REGION TO FINALLY CATCH ITS BREATH FROM THE PREVIOUS STORM.
THE STRONG SHORTWAVE WILL MOVE ACROSS ONTARIO TO SOUTHERN QUEBEC
SATURDAY NIGHT AND SUNDAY. ITS ASSOCIATED ARCTIC COLD FRONT WILL
SWEEP ACROSS OUR REGION SUNDAY MORNING...WITH A REINFORCING SHOT OF
VERY COLD AIR IN ITS WAKE. H85 TEMPS WILL ONCE AGAIN BOTTOM OUT
BETWEEN -16 AND -20C LATE SUNDAY WITH A NORTHWESTERLY FLOW SETTING
UP MORE LAKE EFFECT SNOW. THERE WILL BE A FAIRLY STRONG SFC HIGH
BUILDING ACROSS THE UPPER GREAT LAKES SUNDAY NIGHT THOUGH...SO THIS
WOULD LIMIT THE INTENSITY OF THE LAKE SNOWS.
THE SFC HIGH WILL THEN DRIFT ACROSS THE LOWER GREAT LAKES AND NEW
YORK STATE DURING THE DAY MONDAY WITH LITTLE IF ANY LAKE SNOWS
REMAINING INTACT DUE TO THE HIGHLY SHEARED ENVIRONMENT.
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
FRIDAY NIGHT AND SATURDAY. THIS WILL FURTHER DIMINISH THE LAKE SNOW
SHOWERS WITH JUST FLURRIES EXPECTED FOR THE REGION BY SUNDAY
AFTERNOON.
12Z ECMWF AND 12Z GFS BRING ANOTHER TROUGH WITH TRAILING COLDER AIR
ACROSS THE REGION LATER SUNDAY AND INTO SUNDAY NIGHT. THIS WILL
AGAIN INCREASE THE CHANCES FOR SNOW...FIRST NEAR METRO BUFFALO AND
METRO WATERTOWN...BEFORE ANY LAKE EFFECT SNOW SLIDES SOUTHWARD. FOR
NOW WILL GO WITH LOW POPS UNTIL WE GET CLOSER TO NEXT WEEKEND.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
WEAK LAKE EFFECT PERSISTS SOUTHEAST OF LAKE ERIE WITH WITHERING LAKE
EFFECT SOUTH OF LAKE ONTARIO. NAM12 SHOWS THAT SOME CLOUDS AND WEAK
LAKE SNOW MAY CONTINUE INTO MID MORNING SOUTH OF LAKE ONTARIO AND
EAST OF LAKE ERIE...THEN CLEARING. EXPECT ONLY MVFR FOR A SHORT
TIME. MORE INCLEMENT CONDITIONS EXPECTED TONIGHT AS CIGS DROP TO
MVFR THEN IFR AS DEEPENING LOW MOVES TO WEST OF THE REGION. IFR IN
MODERATE SNOW ALSO EXPECTED LATE OVERNIGHT AS ARE INCREASING WINDS
WITH GUSTS TO 45 KNOTS POSSIBLE OVER WESTERN SOUTHERN TIER AND
WESTERN COUNTIES BY EARLY WEDNESDAY MORNING...AND WIDESPREAD LOW
LEVEL WIND SHEAR.
OUTLOOK...
WEDNESDAY...MVFR/IFR WITH RAIN/SNOW. LOW LEVEL WIND SHEAR LIKELY
EARLY.
THURSDAY...MVFR/IFR SNOW SHOWERS. STRONG SURFACE WINDS LIKELY.
FRIDAY...VFR/MVFR IN SNOW SHOWERS.
&&
.MARINE...
A FAIRLY WEAK SFC PRESSURE GRADIENT WILL BE FOUND OVER LAKES ERIE
AND ONTARIO TODAY AS HIGH PRESSURE WILL DRIFT ACROSS THE REGION.
THIS GRADIENT WILL TIGHTEN UP TONIGHT THOUGH AS A DEEPENING STORM
SYSTEM WILL LIFT FROM OKLAHOMA TO NEAR CHICAGO BY WEDNESDAY MORNING.
THIS WILL RESULT IN STRONG EASTERLIES ON BOTH LAKES BY MIDNIGHT...
WITH THE WINDS VEERING TO SOUTHEAST AS THE NIGHT PROGRESSES. WHILE
THIS WILL KEEP THE HIGHEST WAVES IN CANADIAN WATERS...LATER SHIFTS
WILL HAVE TO DECIDE WHETHER TO ISSUE SMALL CRAFT ADVISORIES FOR
LATER TONIGHT AND WEDNESDAY OR TO ALLOW THE GALE WATCH TO HANDLE
THIS.
IT WILL THEN BE TIME TO BATTEN DOWN THE HATCHES...LITERALLY.
THE POWERFUL EARLY WINTER STORM WILL CROSS THE GREAT LAKES REGION
AND MOVE ACROSS EASTERN CANADA WEDNESDAY AND THURSDAY. WINDS IN THE
WAKE OF THE SYSTEM WILL CONTINUE TO INCREASE ACROSS LAKES ERIE AND
ONTARIO. WINDS WILL INCREASE TO AT LEAST HIGH END GALES DURING THIS
PERIOD...WITH FREQUENT STORM FORCE GUSTS EXPECTED. A GALE WATCH HAS
ALREADY BEEN HOISTED FOR THE OPEN WATERS OF BOTH LAKES...AND
CONSIDERATION WILL HAVE TO BE GIVEN FOR A WATCH FOR STORM FORCE WINDS.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...HIGH WIND WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY
AFTERNOON FOR NYZ012-019>021-085.
HIGH WIND WATCH FROM LATE WEDNESDAY NIGHT THROUGH LATE
THURSDAY NIGHT FOR NYZ006>008.
HIGH WIND WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR NYZ001>005-010-011-013-014.
MARINE...GALE WATCH FROM WEDNESDAY MORNING THROUGH LATE THURSDAY NIGHT
FOR LEZ040-041.
GALE WATCH FROM WEDNESDAY EVENING THROUGH LATE THURSDAY
NIGHT FOR LEZ020.
GALE WATCH FROM WEDNESDAY EVENING THROUGH LATE
THURSDAY NIGHT FOR LOZ042>045.
GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY EVENING
FOR LOZ062>065.
&&
$$
SYNOPSIS...RSH
NEAR TERM...HITCHCOCK/WCH
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...WCH
MARINE...RSH
