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000
FXUS61 KBUF 110423
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1123 PM EST TUE DEC 10 2013

.SYNOPSIS...
LAKE EFFECT SNOW WILL CONTINUE EAST OF THE LAKES THROUGH WEDNESDAY
NIGHT...RESULTING IN SIGNIFICANT ACCUMULATIONS IN THE SNOW BELTS. SOME
LAKE EFFECT SNOW WILL CONTINUE THROUGH THE END OF THE WEEK BEFORE
AN AREA OF LOW PRESSURE POTENTIALLY BRINGS A MORE WIDESPREAD
GENERAL SNOWFALL THIS WEEKEND. TEMPERATURES WILL BE BELOW AVERAGE
THE ENTIRE PERIOD.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
IR SATELLITE SHOWS A SHORTWAVE MOVING EAST OF THE REGION LATE THIS
EVENING. THIS HAS CAUSED WINDS TO SHIFT TO THE WEST-SOUTHWEST BEHIND
IT. OFF LAKE ERIE...THE SHORTWAVE HAS SWEPT UP MOISTURE FROM AN
INTENSE LAKE EFFECT BAND WHICH DEVELOPED EARLY THIS EVENING WITH
THIS NOW ACROSS WESTERN PORTIONS OF THE SOUTHERN TIER.
MEANWHILE...A SECONDARY BAND BEHIND THE SHORTWAVE HAS DEVELOPED FROM
THE CHAUTAUQUA RIDGE TO FAR SOUTH TOWNS...HOWEVER LOWER
EQUILIBRIUM LEVELS AND LESS MOISTURE SHOULD RESULT IN A PERSISTENT
BUT LESS INTENSE BAND OVERNIGHT. THIS WILL KEEP AMOUNTS IN THE 3
TO 6 INCH RANGE IN MOST LOCATIONS...WITH STEADIEST SNOWS ACROSS
HIGHER TERRAIN. SNOWFALL RATES OF AN INCH AN HOUR ARE STILL
EXPECTED IN STEADIER BANDS.

IN THE WAKE OF THE DEPARTING SHORTWAVE...A LAKE EFFECT BAND IS RE-
DEVELOPING OFF LAKE ONTARIO FOLLOWING A BRIEF DISRUPTION WITH THE
WIND SHIFT. THIS HAS BEEN FAIRLY WELL HANDLED BY HIGH RESOLUTION
RGEM/WRF/NAM GUIDANCE...HOWEVER QPF AND WIND FIELDS HAVE BEEN JUST
A TAD NORTH OF WHERE THE ACTUAL BAND IS SETTING UP. SNOWFALL
FORECASTS HAVE BEEN ADJUSTED TO REFLECT THIS.

SO FAR THIS EVENT HAS PRODUCED VERY FLUFFY SNOW...WITH MEAN SNOW
WATER EQUIVALENT RATIOS OF 30:1. THIS IS CONSISTENT WITH
BUFKIT...WHICH SHOWS THE BEST LIFT IN A FAVORABLE TEMPERATURE FOR
SNOW GROWTH...WITH SIMILAR RATIOS LIKELY TO PERSIST FOR THE
REMAINDER OF THE EVENT. EXPECT SNOWFALL RATES TO DIMINISH SLIGHTLY
BEHIND THE SHORTWAVE...WITH THE BAND MEANDERING THEN SHIFTING SOUTH
LATER TONIGHT. EQUILIBRIUM LEVELS DO NOT DROP AS MUCH AS THEY DO OFF
LAKE ERIE...AND WITH THE LONG AND WELL ALIGNED FETCH IN
PLACE...SUSPECT FAIRLY STEADY LAKE SNOWS TO CONTINUE MUCH OF THE
NIGHT. STEADIEST SNOWS WILL BE ON THE TUG HILL...WHERE UPSLOPING
WILL AID LIFT. SNOWFALL RATES OF 2 TO 4 INCHES AN HOUR CAN BE
EXPECTED IN MOST INTENSE BANDS TONIGHT...WITH MOST PERSISTENT BANDS
LIKELY TO PRODUCE 8 TO 16 INCHES OF SNOW OVERNIGHT.

FOR WEDNESDAY OFF LAKE ERIE...

BOUNDARY LAYER FLOW WILL BACK SLIGHTLY TO MORE 260 OR EVEN 250
DEGREES. THIS WILL ALLOW LAKE SNOW TO CONSOLIDATE BACK INTO A SINGLE
BAND ACROSS SOUTHERN ERIE AND WYOMING COUNTIES...POSSIBLY CLIPPING
THE NORTHEAST CORNER OF CHAUTAUQUA COUNTY AS WELL. ELSEWHERE ACROSS
CHAUTAUQUA AND CATTARAUGUS COUNTY...EXPECT A BREAK IN HEAVY SNOW
DURING MUCH OF THE DAY. THE ORGANIZATION BACK INTO A SINGLE
BAND...AND EQUILIBRIUM LEVELS RISING BACK ABOVE 10K FEET SHOULD
PRODUCE HEAVIER SNOWFALL RATES AGAIN WITH A SOLID 5-8 INCHES
ADDITIONAL IN THE BAND CENTERED ON SOUTHERN ERIE OR CENTRAL ERIE
COUNTY.

IT WILL BE AN EXTREMELY DIFFICULT CALL WHETHER THE BAND WILL MAKE IT
BACK NORTH INTO PORTIONS OF THE BUFFALO METRO AREA OR NOT. LATEST
MESOSCALE MODEL GUIDANCE BRINGS THE BAND INTO SOME OF THE
SOUTHTOWNS...BUT OCCASIONALLY WITH STRONG SINGLE BANDS THESE
MESOSCALE MODELS HAVE A SLIGHT SOUTHWARD BIAS. FOR NOW WE HAVE
BROUGHT SEVERAL INCHES BACK INTO THE BUF SOUTHTOWNS AND FAR SOUTHERN
GENESEE COUNTY. IF THIS APPEARS MORE LIKELY...LATER SHIFTS MAY NEED
TO ADD HEADLINES FOR NORTHERN ERIE AND GENESEE COUNTIES.

FOR WEDNESDAY OFF LAKE ONTARIO...

EXPECT SNOWFALL RATES OF 2-4 INCHES PER HOUR AT TIMES...WITH
LOCAL/BRIEF HIGHER RATES POSSIBLE. OUR LOCAL THUNDERSNOW NOMOGRAM
FROM LOCAL RESEARCH BY RSH SUGGESTS AT LEAST SOME POTENTIAL FOR
THUNDERSNOW AS WELL WITHIN THE MOST INTENSE PORTION OF THE BAND.

IF THE BAND IS ABLE TO REMAIN SOMEWHAT STATIONARY OVER A SIMILAR
AREA TONIGHT AND WEDNESDAY...WE MAY SEE 1-2 FEET EACH 12 HOUR PERIOD
ON THE TUG HILL...WITH SOMEWHAT LESSER BUT STILL SIGNIFICANT AMOUNTS
CLOSER TO THE LAKE AND ALSO EAST OF THE TUG HILL. THERE WILL BE A
DOWNSLOPE SHADOW IN THE BLACK RIVER VALLEY WITH SOMEWHAT LOWER
AMOUNTS THERE...BUT AMOUNTS WILL LIKELY INCREASE AGAIN INTO THE
WESTERN FOOTHILLS OF THE ADIRONDACKS WITH ANOTHER UPSLOPE BOOST.

TRAVEL WILL BE EXTREMELY DIFFICULT...IF NOT NEARLY IMPOSSIBLE AT
TIMES WITHIN THE MOST INTENSE PORTION OF THIS BAND. THIS INCLUDES
INTERSTATE 81 FROM PARISH TO ADAMS.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
COLD AIR WILL REMAIN IN PLACE ACROSS THE LOWER LAKES...LEADING TO
CONTINUED IMPRESSIVE OVER-LAKE INSTABILITY AS 850 MB TEMPERATURES
REMAIN AROUND -18C. PASSAGE OF SHORT WAVE WEDNESDAY EVENING WILL
BRING STEERING WINDS AROUND TO WEST NORTHWEST OR NORTHWEST. THIS
WILL FOCUS THE HEAVIEST AND MORE PERSISTENT LAKE SNOWS ALONG THE
CHAUTAUQUA RIDGE OFF LAKE ERIE...WHERE AT LEAST SEVERAL MORE INCHES
OF SNOW WILL BE LIKELY IN FAVORED AREAS. THE ENVIRONMENT OVER LAKE
ONTARIO WILL NOT BE QUITE AS FAVORABLE WITHIN A MORE SHEARED
ENVIRONMENT...BUT WILL STILL MULTIPLE BANDS OF LAKE SNOW SET
UP...HOWEVER THE INTENSITY SHOULD BE LESS THAN THAT OFF OF LAKE
ERIE.

ALSO...00Z RUNS OF THE RGEM/NAM INDICATE STEADIER SNOWS MAY CLIP
NORTHERN WAYNE/CAYUGA COUNTIES ON WEDNESDAY NIGHT AS WINDS SHIFT
TO THE NW. BECAUSE OF THIS...HAVE ISSUED A LAKE EFFECT SNOW
ADVISORY FOR THESE LOCATIONS WHERE 4 TO 7 INCHES OF SNOW ARE
POSSIBLE.

THURSDAY AND THURSDAY NIGHT...MESOSCALE MODELS CONTINUING TO SUGGEST
THE RE-ESTABLISHMENT OF A WESTERLY FLOW REGIME BEHIND UPPER LEVEL
TROUGH. SHEAR PROFILES BECOMING INCREASING FAVORABLE FOR SINGLE LAKE
PLUMES TO DEVELOP EAST OF BOTH LAKES...ESPECIALLY EAST OF LAKE
ONTARIO WHERE THE TUG HILL REGION COULD EASILY SEE ADDITIONAL
SNOWFALL AMOUNTS OF A FOOT OR MORE.

LOW LEVEL FLOW LOOKS TO VEER MORE WEST SOUTHWEST DURING FRIDAY AS
HIGH PRESSURE STARTS TO RIDGE OVER THE OHIO VALLEY. THIS WOULD NUDGE
THE LAKE SNOWS FARTHER TO THE NORTH...WHICH MAY BRING SOME HEAVIER
SNOWS CLOSE TO OR INTO THE BUFFALO METRO AND WATERTOWN AREAS.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
OVERALL MEDIUM RANGE MODEL TREND IS FOR THE DEVELOPING ROCKIES
DURING THE MID WEEK PERIOD TO TRAVEL INTO THE GULF COASTAL REGION
EARLY IN THE PERIOD...BEFORE MAKING A TURN TO THE NORTH TOWARD THE
LOWER GREAT LAKES/NORTHEAST CONUS DURING THE WEEKEND. MODELS SEEM TO
BE CONVERGING AT A HIGHER PROBABILITY OF PRECIPITATION IMPACTING
WESTERN AND CENTRAL NEW YORK DURING THIS TIME FRAME...ESPECIALLY
LATER SATURDAY AND SUNDAY...AS LOW PRESSURE APPROACHES FROM THE OHIO
VALLEY. LATEST GFS/ECMWF INDICATING TWO ENTERS OF LOW PRESSURE...ONE
WORKING THROUGH THE EASTERN LAKES WITH THE MORE SIGNIFICANT LOW
MOVING UP ALONG THE EAST COAST. SOME UNCERTAINTY ON HOW ALL THIS
WILL PLAY OUT...BUT THE SUGGESTION IS THAT A WIDESPREAD SNOW EVENT
WILL DEVELOP SATURDAY THROUGH SUNDAY...WITH PERHAPS SOME WINTRY MIX
OCCURRING ACROSS THE SOUTHEASTERN PORTION OF THE AREA AS SOME WARMER
AIR WRAPS INTO THE SYSTEM. MUCH TOO EARLY IN THE GAME TO PINPOINT
SNOWFALL AMOUNTS...BY THE POTENTIAL DOES EXIST FOR AT LEAST SEVERAL
INCHES.

ONCE THE SYSTEM LIFTS OFF TO THE NORTH...ARCTIC AIR WILL ONCE AGAIN
SURGE INTO THE REGION...WITH THE POTENTIAL FOR LAKE SNOWS
REDEVELOPING ON A NORTHWEST FLOW...WITH THE BEST POTENTIAL FOR THE
MOST SIGNIFICANT LAKE SNOW FROM SUNDAY NIGHT INTO EARLY MONDAY. HIGH
PRESSURE RIDGING ACROSS THE REGION LATE MONDAY SHOULD DIMINISH LAKE
POTENTIAL. NEXT CLIPPER LOW LOOKS TO APPROACH THE GREAT LAKES
TUESDAY.

&&

.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
LAKE EFFECT SNOW WILL BE THE MAIN CONCERN THROUGH THE TAF PERIOD AS
ANY BAND OF LAKE SNOW WILL PRODUCE IFR/LIFR CONDITIONS. AN INTENSE BAND OF
LAKE EFFECT SNOW OFF LAKE ERIE WILL MOVE SOUTH OF THE KBUF/KIAG AND
KROC AREAS AFTER 00Z AND SETTLE OVER THE HIGHLANDS OF THE WESTERN
SOUTHERN TIER. THIS WILL AFFECT KJHW WITH LIFR CONDITIONS THROUGH
03Z THEN A SLIGHT SHIFT TO THE NORTH WILL FOCUS THE LAKE SNOW BAND
BETWEEN THE TAF SITES OF WESTERN NY. THERE MAY BE ANOTHER EXCURSION
NORTHWARD AT MIDDAY ON WEDNESDAY...AFFECTING KBUF ONCE AGAIN.

OFF LAKE ONTARIO HEAVY LAKE EFFECT SNOW WILL SPEND MOST OF THE TIME
ACROSS THE TUG HILL REGION BETWEEN KART AND KFZY WITH LOCAL IFR. A
BRIEF PERIOD OF LIGHT SNOW IS POSSIBLE WITH BRIEF IFR THIS EVENING
AT KART...BUT OTHERWISE VFR SHOULD PREVAIL AS THE BAND REMAINS
SOUTH.

OUTLOOK...
WEDNESDAY NIGHT...VFR EXCEPT AREAS OF IFR EAST OF THE LAKES
IN HEAVY LAKE EFFECT SNOW.
THURSDAY...VFR EXCEPT MVFR/IFR IN LAKE EFFECT SNOW SHOWERS SOUTHEAST
OF THE LAKES.
FRIDAY...VFR EXCEPT MVFR/IFR IN LAKE EFFECT SNOW SHOWERS EAST OF THE
LAKES.
SATURDAY AND SUNDAY...MVFR/IFR WITH A CHANCE OF SNOW.

&&

.MARINE...
WESTERLY GALES ON BOTH LAKES. BRIEF GUSTS TO 45 KNOTS ARE POSSIBLE
THROUGH EARLY MORNING...IMMEDIATELY BEHIND AN EXITING UPPER LEVEL
DISTURBANCE. THE GALES WILL CONTINUE THROUGH WEDNESDAY ON LAKE
ONTARIO BEFORE COMING DOWN SOME WEDNESDAY NIGHT AND THURSDAY.
SOLID SMALL CRAFT ADVISORY CONDITIONS WILL CONTINUE MOST OF THE
TIME THROUGH THE END OF THE WEEK.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW WARNING UNTIL 4 AM EST THURSDAY FOR
     NYZ006>008-012-019-020-085.
     LAKE EFFECT SNOW ADVISORY FROM 7 PM WEDNESDAY TO 9 AM EST
     THURSDAY FOR NYZ004-005.
     LAKE EFFECT SNOW ADVISORY UNTIL 3 AM EST THURSDAY FOR NYZ021.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST WEDNESDAY FOR LEZ020.
         GALE WARNING UNTIL 7 AM EST WEDNESDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 6 PM EST WEDNESDAY FOR
         LOZ030.
         GALE WARNING UNTIL 1 PM EST WEDNESDAY FOR LOZ043>045-
         063>065.
         GALE WARNING UNTIL 10 AM EST WEDNESDAY FOR LOZ042-062.
         SMALL CRAFT ADVISORY FROM 4 AM TO 4 PM EST WEDNESDAY
         FOR SLZ022-024.

&&

$$

SYNOPSIS...APFFEL
NEAR TERM...APFFEL/HITCHCOCK
SHORT TERM...TMA/APFFEL
LONG TERM...TMA
AVIATION...WCH
MARINE...APFFEL/HITCHCOCK