Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 210158
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
858 PM EST THU NOV 20 2014

.SYNOPSIS...
SIGNIFICANT LAKE EFFECT SNOWS WILL CONTINUE THROUGH TONIGHT AND
FRIDAY MORNING BEFORE STARTING TO WEAKEN LATER IN THE AFTERNOON ON
FRIDAY. THE LAKE SNOWS WILL END ALTOGETHER FRIDAY NIGHT AS HIGH
PRESSURE PASSES BY TO THE SOUTH OF THE AREA. MUCH WARMER AIR WILL
ARRIVE OVER THE WEEKEND AND INTO EARLY NEXT WEEK ALONG WITH RAIN
SHOWERS AT TIMES...POTENTIALLY BRINGING A FLOOD RISK TO AREAS WHICH
WERE BURIED BY LAKE EFFECT SNOW. TEMPERATURES WILL THEN TURN COLDER
AGAIN FOR THE SECOND HALF OF NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
THERE IS LIGHT AT THE END OF THE LAKE EFFECT TUNNEL ONCE WE GET
THROUGH THE NEXT 18 HOURS OR SO.

OFF LAKE ERIE EXPECT STORM TOTALS OF 3 TO 4 FEET FROM THE SECOND
EVENT CENTERED ONE ROW OF TOWNS SOUTH OF WHERE THE HEAVIEST SNOW
FELL FROM THE FIRST EVENT. THIS WOULD INCLUDE LOCATIONS FROM SILVER
CREEK TO ANGOLA...BOSTON...EAST AURORA...WITH 1 TO 2 FEET COMMON
ACROSS THE HARDEST HIT TOWNS FROM THE FIRST EVENT...AND ALSO FARTHER
SOUTH THROUGH NORTHERN AND WESTERN CHAUTAUQUA COUNTY...WESTERN
CATTARAUGUS COUNTY...AND INTO PORTIONS OF SOUTHERN GENESEE AND
NORTHERN/WESTERN WYOMING COUNTY. NOTE THIS COUNTS SNOW WHICH HAS
ALREADY FALLEN SINCE LAST EVENING.

OFF LAKE ONTARIO EXPECT STORM TOTALS OF 1 TO 2 FEET FROM JUST SOUTH
AND EAST OF WATERTOWN DOWN ACROSS CENTRAL OSWEGO COUNTY...WITH LOCAL
AMOUNTS POSSIBLY GETTING OVER 2 FEET ON THE TUG HILL PLATEAU. NOTE
THIS COUNTS SNOW WHICH HAS FALLEN SINCE LAST EVENING.

OFF LAKE ERIE...
AN INTENSE BAND OF LAKE EFFECT SNOW IS IN PLACE FROM DUNKIRK
NORTHEAST ACROSS SOUTHERN ERIE COUNTY...THE IMMEDIATE BUFFALO
SOUTHTOWNS...AND EAST ALONG THE GENESEE/WYOMING COUNTY LINE.
SNOWFALL RATES OF 3 TO 5 INCHES PER HOUR CONTINUE WITHIN THIS BAND
AND A FEW RUMBLES OF THUNDER AND LIGHTNING ARE ALSO POSSIBLE.
UPSTREAM RADAR TRENDS SHOW THE START OF A SOUTHWARD DRIFT OVER THE
WESTERN BASIN OF LAKE ERIE...AND THIS FOLLOWS WELL WITH THE NAM
MODEL WHICH HAS BEEN PERFORMING VERY WELL WITH BAND MOTION THROUGH
THIS EVENT.

REGIONAL NWS DOPPLER RADARS AND LOCAL MEDIA RADARS INDICATE THAT THE
LAKE ERIE BAND IS EASILY EXTENDING TO THE EAST ACROSS THE FINGER
LAKES REGION...WITH STEADY MODERATE SNOW FOUND OVER LIVINGSTON AND
ONTARIO COUNTIES. WILL HOIST A LAKE EFFECT SNOW WARNING FOR
LIVINGSTON COUNTY AND AN ADVISORY FURTHER EAST FOR ONTARIO TO
ACCOUNT FOR THIS ACTIVITY...WHICH SHOULD DROP SOUTH AND END IN
THESE AREAS NEAR OR SHORTLY AFTER MIDNIGHT.

WITH THIS IN MIND...EXPECT THE BAND TO REMAIN IN PLACE THROUGH 8 PM
THEN BEGIN A FAIRLY RAPID SHIFT SOUTHWARD. IT WILL LIKELY COME
BODILY ONSHORE ALONG THE CHAUTAUQUA COUNTY SHORELINE AND DELIVER A
FEW HOURS OF VERY HEAVY SNOW ALONG THE LAKE ERIE SHORE AND
CHAUTAUQUA RIDGE. OVERNIGHT BOUNDARY LAYER WINDS VEER STEADILY TO
THE NORTHWEST WHICH WILL PUSH THE INITIAL SINGLE BAND INLAND AND
WEAKEN IT...TO BE REPLACED BY MORE OF A NORTHWEST FLOW/UPSLOPE
REGIME. THIS WILL FOCUS THE HEAVIEST SNOW ACROSS THE HIGHER TERRAIN
OF THE CHAUTAUQUA RIDGE OVERNIGHT WITH LIGHTER SNOW ALONG THE LAKE
ERIE SHORE.

ON FRIDAY THE NORTHWEST FLOW/UPSLOPE REGIME WILL CONTINUE. THE BEST
SNOW SHOULD BE IN THE MORNING...BY AFTERNOON INVERSION HEIGHTS LOWER
SUBSTANTIALLY AND BACKGROUND SYNOPTIC SCALE MOISTURE DECREASES
QUICKLY...WHICH SHOULD BRING A RAPID WEAKENING. WHATEVER IS LEFT
WILL TRY TO SHIFT BACK NORTH TOWARDS BUFFALO LATE FRIDAY AND FRIDAY
EVENING...BUT THERE SHOULD NOT BE MUCH LEFT BESIDES A FEW LIGHT SNOW
SHOWERS.

OFF LAKE ONTARIO...
THE BAND OF MODERATE TO HEAVY LAKE EFFECT SNOW HAS BEEN CENTERED
OVER THE TUG HILL SINCE NIGHTFALL...AND IS NOW SLOWLY STARTING TO
SETTLE TO THE SOUTH. HAVE THUS REMOVED JEFFERSON COUNTY FROM THE
WARNING. THE BAND WILL CONTINUE SOUTH ACROSS OSWEGO COUNTY DURING
THE REMAINING OVERNIGHT HOURS WITH SNOWFALL RATES OF ONE TO TWO
INCHES AN HOUR.

LATEST MODEL GUIDANCE CONTINUES TO SUGGEST A RAPID SHIFT TO
NORTHWEST WINDS WILL OCCUR...AND PUSH AN EAST/WEST BAND BODILY
ONSHORE LATE TONIGHT AND EARLY FRIDAY MORNING. THIS WILL BRING A
BURST OF SNOW TO THE ENTIRE SOUTH SHORE OF THE LAKE INCLUDING THE
ROCHESTER AREA WHERE A QUICK 1 TO 2 INCHES IS POSSIBLE. THE BAND
SHOULD STILL BE STRONGER FARTHER EAST INTO WAYNE AND NORTHERN CAYUGA
COUNTIES. ONCE THE BAND MOVES ONSHORE IT SHOULD BREAK APART...AND BE
REPLACED BY A WIDER SPRAY OF MULTIPLE BANDS IN MANY AREAS SOUTHEAST
OF THE LAKE.

ALL OF THIS COMBINED SHOULD PRODUCE ADVISORY TYPE ACCUMULATIONS IN
WAYNE AND NORTHERN CAYUGA COUNTIES FROM LATE TONIGHT THROUGH FRIDAY.
AMOUNTS SHOULD REMAIN BELOW ADVISORY CRITERIA FOR ROCHESTER.

BY FRIDAY AFTERNOON WHATEVER REMAINS OF THE LAKE EFFECT WILL BE MUCH
WEAKER...ALTHOUGH THERE IS SOME SUGGESTION IN MESOSCALE MODEL
GUIDANCE THAT THE LAKE ONTARIO BAND MAY BRIEFLY INTENSITY AGAIN
ACROSS OSWEGO COUNTY AND THE TUG HILL FRIDAY EVENING AS FLOW BACKS
AND BECOMES MORE WESTERLY...INCREASING FETCH.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH MONDAY NIGHT/...
LAKE EFFECT SNOW WILL DIMINISH TO START THIS TIME PERIOD OFF BOTH
EASTERN GREAT LAKES. ALOFT A FRONT OF WARMER AIR WILL BE ADVANCING
NORTHWARD UP LAKE ERIE AND THIS WARMING WILL GREATLY REDUCED THE
CAPPING INVERSION OFF LAKE ERIE WITH INCREASE WIND SHEAR ENDING ANY
LINGER LAKE EFFECT SNOW NEAR SKI COUNTRY THROUGH THE EVENING HOURS.

OFF LAKE ONTARIO A STILL HEALTHY BAND OF LAKE EFFECT SNOW WILL BE
ONGOING WITH A WNW FLOW. THIS BAND OF SNOW WILL FOCUS ON AREAS SE OF
LAKE ONTARIO WITH SEVERAL MORE INCHES OF SNOW BEFORE WARMING FROM
THE SOUTH...AND INCREASE WIND SHEAR ENDS THE LAKE EFFECT SNOW BY
SATURDAY MORNING OVER THE TUG HILL REGION.

SATURDAY WILL BE THE BEGINNING OF WARMING ACROSS WNY. A
SOUTHWESTERLY FLOW AROUND A BROAD AREA OF HIGH PRESSURE OFF THE
CAROLINA COASTLINE WILL BRING TEMPERATURES ALOFT AT 850 HPA UP ABOVE
FREEZING. MEANWHILE MOISTURE ADVECTION FROM THE MIDWEST WILL BRING
CHANCES FOR PRECIPITATION AS WARM...MOIST AIR IS LIFTED UPWARD OVER
THE COOLER AIR WITHIN THE BOUNDARY LAYER. EXPECT SOME LIGHT
PRECIPITATION TO START ACROSS WNY LATER IN THE DAY SATURDAY...AND BY
SATURDAY EVENING FOR AREAS EAST OF LAKE ONTARIO. SOME LINGER POCKETS
OF BELOW FREEZING TEMPERATURES AT THE GROUND MAY PRODUCE SOME SPOTTY
FREEZING RAIN AT THE ONSET...ESPECIALLY ACROSS THE HILLS SOUTH OF
BUFFALO AND ROCHESTER...AND ALSO VALLEYS TO THE EAST OF LAKE
ONTARIO.

LIGHT PRECIPITATION WILL CONTINUE INTO SUNDAY WITH ABUNDANT LOW
LEVEL MOISTURE LIFTED ON THE NOSE OF A 50 KNOT LLJ. WITH THE WARMING
PATTERN USUALLY WINDS ALOFT HAVE A HARD TIME MIXING DOWN DUE TO THE
POOR LAPSE RATES...AND JUST A BREEZY DAY WILL BE FOUND SATURDAY AND
SUNDAY.

SUNDAY A BREAK IN PRECIPITATION IS LIKELY AS THE OVERHEAD RIDGE
STRENGTHENS. THOUGH LIKELY STILL CLOUDY A STRONG WARM AIR ADVECTION
PATTERN WILL BRING 850 HPA TEMPERATURES UP TO 6C SUNDAY AND TO NEAR
10C BY EARLY MONDAY. THESE SOUTHERLY WINDS...ALONG WITH HEIGHT RISES
ALOFT ON SUNDAY WILL BRING OUR SURFACE HIGHS INTO THE LOWER 50S.
COUPLED WITH THE WARMING TEMPERATURES WILL ALSO BE A RISE IN SURFACE
DEWPOINTS. DEWPOINTS WILL START TO RISE INTO THE MID TO UPPER 30S
SUNDAY. THE COMBINATION OF WARMING TEMPERATURES...INCREASE SOUTHERLY
WINDS AND RISING DEWPOINTS SHOULD ALLOW FOR THE DEEP SNOWPACK EAST
OF BOTH GREAT LAKES TO COMPACT AND DIMINISH IN HEIGHT.

SUNDAY NIGHT AND INTO MONDAY IS WHEN THE BEST CHANCES FOR RAINFALL
TO OCCUR. ON THE FORCING OF A WARM FRONT BOUNDARY LIFTING NORTHWARD
FROM A LOW PRESSURE SYSTEM OVER THE WESTERN GREAT LAKES...A LIGHT
RAINFALL IS LIKELY ACROSS OUR REGION. AT THIS TIME RAINFALL DOES NOT
LOOK TO BE SIGNIFICANT WITH A SHORT PERIOD OF RAINFALL MEASURING ON
THE ORDER OF A QUARTER TO ONE HALF INCH.

THE MAJOR CONCERN THIS TIME PERIOD WILL BE THE POTENTIAL FOR
FLOODING. LIQUID STORED IN THE RECENTLY FALLEN LAKE EFFECT SNOW IS
LIKELY TO BE AT LEAST SEVERAL INCHES. SUNDAY NIGHT WILL REMAIN MILD
WITH LOWS REMAINING WELL ABOVE FREEZING. BY MONDAY SURFACE
TEMPERATURES WILL BE CLIMBING TOWARDS THE UPPER 50S TO AROUND 60F
WHICH WITH DEWPOINTS NOW IN THE MID TO UPPER 40S AND SOUTHERLY WINDS
SHOULD ALLOW FOR MUCH OF THE SNOW TO MELT. THE HIGH LIQUID IN THE
SNOWPACK COMBINED THE FALLING RAINFALL COULD LEAD TO FLOODING...BOTH
URBAN/AREAL AS WELL AS SIGNIFICANT RISES ON LOCAL STREAM/CREEKS AND
RIVERS.

THE BASE OF THE UPPER LEVEL TROUGH AND ITS COLD AIR WILL REMAIN JUST
TO OUR WEST THROUGH THE COURSE OF MONDAY NIGHT. THIS WILL ALLOW FOR
SURFACE TEMPERATURES TO REMAIN ABOVE FREEZING THROUGH THE NIGHT AND
ALLOW FOR SNOWPACK MELTING TO CONTINUE. WITH THE TROUGH NEARBY WILL
CARRY A LOW CHANCE POP FOR A PASSING SHOWER.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
FOR THE TUESDAY THROUGH THURSDAY TIME PERIOD COOLING TEMPERATURES
WILL END THE THREAT OF FLOODING...BUT AGAIN RENEW THE LAKE EFFECT
SNOW POTENTIAL.

ON TUESDAY AN AMPLIFIED UPPER AIR PATTERN WILL CONTINUE AS A LONG
WAVE TROUGH WILL BE FOUND OVER THE GREAT LAKES REGION AND DOWN
TOWARDS THE SOUTHERN MISSISSIPPI VALLEY. THIS TROUGH WILL SPLIT THE
RIDGE TO OUR EAST (PRIOR WARM AIRMASS) AND RIDGE ACROSS THE WEST.

WITH SHORTWAVES PASSING THROUGH THIS UPPER LEVEL TROUGH...AND WITH
THIS TROUGH NOW NEARING OUR REGION WILL MAINTAIN LOW CHANCE POPS FOR
A MIX OF RAIN AND SNOW. AS THE COLD AIR DEEPENS THROUGH THE
DAY...LAKE EFFECT SNOW WILL AGAIN BECOME A CONCERN.

BY TUESDAY NIGHT TEMPERATURES ALOFT AT 850 HPA WILL HAVE DROPPED TO
NEAR -10C...AND FALLING. ALOFT THIS UPPER LEVEL LOW TO OUR WEST WILL
NOT BE AS DEEP AS THIS CURRENT WEEK OF LAKE EFFECT SNOW...COLD AIR
NOT AS DEEP AND CAPPING INVERSION HEIGHTS NOT AS TALL. THAT SAID
PARAMETERS ARE STILL LOOKING FAVORABLE FOR ANOTHER BAND OF LAKE
EFFECT SNOW STARTING TUESDAY PM ACROSS AREAS NORTHEAST OF THE
LAKES...THEN DROPPING SOUTHWARD THROUGH TUESDAY NIGHT AND WEDNESDAY.
WITH THE COLD AIR NOT AS DEEP THERE MAY EVEN BE A LITTLE RAIN MIXED
IN WITH THE BANDS OF SNOW DURING THE DAY WEDNESDAY.

A SHORTWAVE WILL CROSS THE EASTERN GREAT LAKES WEDNESDAY/WEDNESDAY
NIGHT...WHICH MAY DISRUPT THE BANDS SOME...BEFORE A WESTERLY WIND
CARRIES THE LAKE EFFECT SNOW INLAND TO AREAS EAST OF THE LAKES...AND
SOUTH OF BUFFALO/WATERTOWN FOR WEDNESDAY NIGHT.

BANDS OF LAKE EFFECT SNOW WILL FADE EARLY THURSDAY AS WE GET A
LITTLE WARM AIR ADVECTION ALOFT AHEAD OF AN APPROACHING SHORTWAVE.
THIS SHORTWAVE MAY BRING SOME LIGHT GENERAL SNOW TO WNY BY LATE IN
THE DAY THURSDAY.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
OUTSIDE OF LAKE EFFECT AREAS CONDITIONS WILL BE MAINLY VFR THROUGH
THE PERIOD WITH GUSTY WINDS TONIGHT WITH DIMINISHING WINDS LATE
TONIGHT AND FRIDAY AS HIGH PRESSURE MOVES ACROSS THE REGION.

AS FOR LAKE EFFECT...THE PLUME OFF LAKE ERIE IS SOUTH OF KBUF AND
WILL CONTINUE TO EDGE SLOWLY NORTHWARD THROUGH THE EARLY EVENING
HOURS. THE BAND WILL RAPIDLY PUSH SOUTH AND BECOME MORE MULTI BAND
IN NATURE LATE THIS EVENING. THIS WILL RESULT IN DETERIORATING
CONDITIONS AT KJHW AND KELZ WITH IFR/LIFR CONDITIONS ANTICIPATED BY
ABOUT 02Z OR SO.

OFF LAKE ONTARIO... A PLUME OF SNOW EXTENDS EAST ACROSS THE TUG HILL
PLATEAU. THIS BAND WILL SETTLE TO THE SOUTH OVERNIGHT AND BECOME
MULTI BAND IN NATURE BY MORNING OVER THE COUNTIES SOUTHEAST OF THE
LAKE. THIS WILL RESULT IN CONTINUING IMPROVEMENT AT KART...BUT
DETERIORATING CONDITIONS CAN BE EXPECTED AT KROC AFTER 08Z.

OUTLOOK...
SATURDAY...VFR.
SATURDAY NIGHT THROUGH MONDAY...PERIODS OF IFR/MVFR IN RAIN. LLWS
POSSIBLE SUNDAY NIGHT AND INTO MONDAY MORNING.
TUESDAY...MAINLY VFR WITH A CHANCE OF RAIN/SNOW SHOWERS.

&&

.MARINE...
WHILE DEEP LOW PRESSURE PASSING BY TO THE NORTH OF THE LOWER GREAT
LAKES WILL CONTINUE TO GENERATE FAIRLY STRONG WINDS THROUGH
TONIGHT...WINDS HAVE DROPPED BELOW GALE FORCE ON LAKE ONTARIO. HAVE
THUS DROPPED THE GALE WARNING AND HAVE REPLACED IT WITH SMALL CRAFT
ADVISORIES FOR THE LAKE ONTARIO NEARSHORE WATERS. MEANWHILE SCA`S
WILL REMAIN IN PLACE FOR THE LAKE ERIE NEARSHORE WATERS ALONG WITH
THE IAG AND ST LAWRENCE RIVERS.

THE STRONG WINDS WILL START TO SUBSIDE LATER TONIGHT AS HIGH
PRESSURE WILL BUILD ACROSS THE GREAT LAKES REGION AND WEAKEN THE
INFLUENCING SFC PRESSURE GRADIENT. WHILE THE AREA OF HIGH PRESSURE
WILL PASS OVER LAKES ERIE AND ONTARIO ON FRIDAY...WINDS WILL LIKELY
REMAIN HIGH ENOUGH TO WARRANT SMALL CRAFT ADVISORIES ON LAKE ONTARIO.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW WARNING UNTIL 6 PM EST FRIDAY FOR NYZ006.
     LAKE EFFECT SNOW ADVISORY FROM 1 AM TO 6 PM EST FRIDAY FOR
     NYZ004-005.
     LAKE EFFECT SNOW WARNING UNTIL NOON EST FRIDAY FOR NYZ008-019-
     020.
     LAKE EFFECT SNOW ADVISORY UNTIL NOON EST FRIDAY FOR NYZ021.
     FLOOD WATCH FROM SUNDAY AFTERNOON THROUGH WEDNESDAY MORNING
     FOR NYZ010>012-085.
     LAKE EFFECT SNOW WARNING UNTIL 1 AM EST FRIDAY FOR NYZ012-013-
     085.
     LAKE EFFECT SNOW ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
     NYZ014.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LEZ020.
         SMALL CRAFT ADVISORY UNTIL 8 PM EST FRIDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
         LOZ030.
         SMALL CRAFT ADVISORY UNTIL 4 AM EST SATURDAY FOR
         LOZ043>045.
         SMALL CRAFT ADVISORY UNTIL 9 AM EST FRIDAY FOR LOZ042.
         SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
         SLZ022-024.

&&

$$

SYNOPSIS...HITCHCOCK
NEAR TERM...HITCHCOCK/RSH
SHORT TERM...THOMAS
LONG TERM...THOMAS
AVIATION...HITCHCOCK/RSH
MARINE...HITCHCOCK/RSH







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