Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 201157
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
657 AM EST THU NOV 20 2014

.SYNOPSIS...
SIGNIFICANT LAKE EFFECT SNOWS WILL ONCE AGAIN BE FOCUSED NORTHEAST
OF BOTH LAKES TODAY...AS A FRESH COLD AIRMASS WILL DEEPEN OVER THE
REGION. THE LAKE SNOWS WILL SETTLE TO THE SOUTH TONIGHT WHERE THEY
WILL BE CONCENTRATED OVER THE MORE TYPICAL LAKE SNOW BELTS OF THE
WESTERN SOUTHERN TIER AND SOUTH OF THE TUG HILL THROUGH FRIDAY.
NOTICEABLY MILDER AIR WILL THEN SURGE INTO OUR REGION DURING THE
UPCOMING AND LAST INTO THE EARLY PART OF THE NEW WORK WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
...RENEWED LAKE EFFECT WILL DUMP MULTIPLE FEET OF SNOW ON AREAS
NORTHEAST OF BOTH LAKES THROUGH TONIGHT...INCLUDING THE AREA THAT
WAS JUST CRIPPLED WITH 3 TO 5 FEET OF SNOW DOWNWIND OF LAKE ERIE...

A PATTERN VERY REMINISCENT OF LAST YEARS WINTER WILL BE IN PLACE
ACROSS NORTH AMERICA TODAY...AS RIDGING WILL BE FOUND OVER THE
WESTERN THIRD OF THE CONTINENT WHILE AN ANOMALOUSLY DEEP TROUGH WILL
BE CENTERED OVER THE GREAT LAKES. THIS WILL KEEP THE DOOR WIDE OPEN
FOR COLD AIR TO CONTINUE TO POUR SOUTHWARDS ACROSS THE RELATIVELY
WARM WATERS OF THE GREAT LAKES. THEREIN LIES THE FORECAST PROBLEM
FOR WESTERN AND NORTH CENTRAL NEW YORK.

A DEEP...CYCLONIC FLOW OF -14C H85 AIR WILL CIRCULATE ACROSS LAKES
ERIE AND ONTARIO TODAY AND TONIGHT. THIS WILL ESTABLISH IMPRESSIVE
INSTABILITY OVER THE LOWER GREAT LAKES...AND WITH A LOW SHEAR
ENVIRONMENT AND A CAPPING INVERSION RISING FROM 10K FT TO AT LEAST
15K...THE INGREDIENTS WILL BE IN PLACE FOR ANOTHER PROMINENT ROUND
OF LAKE EFFECT SNOW. WHILE THIS WILL CERTAINLY HAVE AN IMPACT ON
SITES EAST AND NORTHEAST OF LAKE ONTARIO...A GREATER CONCERN WILL BE
NORTHEAST OF LK ERIE WHERE THIS SNOW WILL FALL ON AREAS THAT
RECEIVED UP TO FIVE FEET OF SNOW JUST 30 HOURS AGO.

A FAIRLY PERSISTENT 250 TO 260 FLOW IS FORECAST BY THE BULK OF THE
ON STATION 6KM MESOSCALE MODELS...WHICH JUST HAPPENED TO PERFORM
ADMIRABLY DURING THE JUST ENDED HISTORIC EVENT. OUR FORECAST WILL BE
BASED ON A BLEND OF CONTINUITY AND AN AVERAGE OF THESE 6KM MODELS...
WITH A SUBTLE TENDENCY TO KEEP THE AXIS OF THE BAND ABOUT 10 MILES
NORTH OF THE MODELS DUE TO THE EARLY SEASON LAKE AGGREGATE EFFECT.
THIS WILL PLACE THE BAND TODAY OVER THE CHAUTAUQUA COUNTY SHORE AND
STRETCH IT NORTHEAST ACROSS THE SOUTHERN HALF OF ERIE COUNTY...WITH
THE NORTHERN EXTENT OF THE BAND OVER THE BUFFALO SOUTHTOWNS WHILE
REMAINING JUST TO THE SOUTH OF THE BUFFALO METROPOLITAN AREA.
SNOWFALL RATES WILL ONCE AGAIN EXCEED 3 INCHES PER HOUR AT TIMES
UNDER THE BAND. PLACES LIKE ORCHARD PARK...HAMBURG...EAST AURORA
AND MARILLA COULD EASILY PICK UP ONE TO TWO FEET OF SNOW TODAY
TOGETHER WITH THE OCCASIONAL RUMBLE OF THUNDER. THE BAND WILL OSCILLATE
A LITTLE DURING THE DAY...BUT OVERALL EXPECT THE NORTHERN EXTENT TO
BE A MERE 5 OR SO MILES SOUTH OF THE LAST EVENT.

THE FLOW WILL VEER 300 DURING THE COURSE OF TONIGHT. THIS WILL
DIRECT THE LAKE SNOWS FURTHER SOUTH ACROSS THE WESTERN SOUTHERN TIER
WHERE A FOOT OF ACCUMULATION IS EXPECTED. THE HIGHEST AMOUNTS ARE
EXPECTED ALONG AND JUST EAST OF THE CHAUTAUQUA RIDGE.

OFF LAKE ONTARIO...A MORE COMPLICATED PATTERN IS IN PLACE WITH A
DOUBLE BAND AT 12Z. THUS AMOUNTS WILL BE HIGHLY VARIABLE...WITH
SOME AREAS SEEING UPWARDS OF 2 FEET. SNOWFALL RATES OF 2 INCHES
AN HOUR ARE EXPECTED AS A DEEPER SYNOPTIC MOISTURE FIELD WILL BE
IN PLACE. LIKE LAKE ERIE...THE FLOW OVER LAKE ONTARIO WILL VEER TO
AROUND 300 DURING THE COURSE OF TONIGHT. THIS WILL PUSH THE LAKE
SNOWS SOUTH ACROSS THE TUG HILL TO OSWEGO AND NORTHERN CAYUGA
COUNTIES. SNOWFALL RATES OF 2 INCHES AN HOUR SHOULD BE COMMON AS
THE BAND MAKES THIS TREK TO THE SOUTH.

OUTSIDE OF THE LAKE EFFECT AREAS...IT WILL BE COLD WITH SOME
FLURRIES. TEMPERATURES TODAY WILL BE GENERALLY IN THE MID TO UPPER
20S WITH GUSTY SOUTHWEST WINDS PRODUCING WIND CHILL VALUES IN THE
TEENS. MERCURY READINGS TONIGHT WILL SETTLE INTO THE TEENS IN MOST
AREAS...ALTHOUGH READINGS WILL REMAIN IN THE 20S WHERE LAKE
CLOUDS/PCPN WILL BE COMMON NEAR LAKE ONTARIO.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
LAKE EFFECT STORM ROUND 2 WILL COME TO AN END FRIDAY NIGHT OFF BOTH
LAKES THEN EXPECTING A WARM ADVECTION PATTERN TO SET UP THROUGH
SATURDAY. THIS WILL BRING WARMING TEMPERATURES UNDER SOUTHERLY WINDS
ALONG WITH THE CHANCE FOR SOME MIXED PRECIPITATION AS VERTICAL
TEMPERATURE PROFILES SHOW A WARM NOSE TRIES TO PUSH ABOVE FREEZING
BEFORE SURFACE TEMPERATURES DO.

FOR THE LAKE EFFECT OFF LAKE ERIE...
LAKE INDUCED EQUILIBRIUM LEVELS WILL RUN AROUND 15KFT FRIDAY MORNING
BEFORE DROPPING STEADILY DURING THE DAY FRIDAY AS HIGH PRESSURE
SHIFTS FROM THE OHIO VALLEY EAST TO THE MID-ATLANTIC WITH ASSOCIATED
RIDGING DRIVING DOWN A SUBSIDENCE INVERSION. EXPECT MOST OF THE SNOW
TO BE CONFINED TO CHAUTAUQUA AND THE WESTERN HALF OF CATTARAUGUS
COUNTIES DURING THE DAY UNDER A 290-300 DEGREE FLOW. THE LAKE SNOW
SHOULD STEADILY WEAKEN FRIDAY AFTERNOON AS INVERSION HEIGHTS LOWER.
THE STEERING WINDS ARE FORECAST TO BACK AS THE SURFACE RIDGING
BUILDS ACROSS WESTERN NY AND A WEAK BAND OF SNOW SHOWERS WILL SHIFT
BACK NORTH OVER SOUTHERN ERIE COUNTY WHILE DISSIPATING.

OFF LAKE ONTARIO...
LAKE INDUCED EQUILIBRIUM LEVELS WILL RUN CLOSE TO 18KFT FRIDAY
BEFORE DROPPING STEADILY FRIDAY AND FRIDAY NIGHT ALSO DUE TO A
LOWERING INVERSION. FRIDAY MORNING THE BAND IS EXPECTED TO EXTEND
ACROSS THE SOUTHEAST LAKE SHORE THEN IS FORECAST TO DROP SOUTH TO
BETWEEN ROCHESTER AND OSWEGO AS WINDS VEER TO AROUND 310 DEGREES.
CURRENT THINKING STILL REMAINS THAT THE TRANSITORY NATURE OF THIS
BAND SHOULD PREVENT SIGNIFICANT ACCUMULATIONS OVER ANY ONE LOCATION
SO NOT ENOUGH CONFIDENCE YET ON HIGHER AMOUNTS IN THOSE AREAS BUT
THIS WILL CONTINUE TO BE MONITORED.

SIMILAR TO WHAT IS EXPECTED ON LAKE ERIE BUT SEVERAL HOURS
LATER...BOUNDARY LAYER FLOW IS FORECAST TO BACK AS SURFACE RIDGING
BUILDS NORTH. THIS BACKING FLOW WILL CARRY THE LAKE EFFECT BACK
NORTH ACROSS OSWEGO COUNTY DURING THE EVENING EVENTUALLY DISSIPATING
ACROSS THE TUG HILL UNDER THE LOWERING INVERSION.

ON SATURDAY THE STRONG SURFACE HIGH OVER THE MID-ATLANTIC IS
FORECAST TO SHIFT EAST OFF THE COAST. STRENGTHENING SOUTHWEST FLOW ON
THE BACKSIDE OF THE HIGH WILL ADVECT MUCH WARMER AIR AND GULF
MOISTURE NORTHWARD ACROSS THE GREAT LAKES. WHILE THE MORNING SHOULD
REMAIN DRY WITH JUST INCREASING CLOUDS...CHANCES OF MIXED
PRECIPITATION INCLUDING SLEET AND POSSIBLE FREEZING RAIN WILL SHIFT
OVER WESTERN AND CENTRAL NEW YORK AS WARM AIR OVERRIDES STILL
SUB-FREEZING SURFACE TEMPS. EXACT P-TYPE WILL DEPEND ON THE SPEED AT
WHICH TEMPERATURE COLUMNS WARM AND MOISTEN. NAM FORECAST WARM LAYER
TEMPS QUICKLY RISE SEVERAL DEGREES ABOVE FREEZING BY MIDDAY SATURDAY
SO ANY MIX IF IT OCCURS SHOULD BE BRIEF AND QUICKLY CHANGE OVER TO
SOME LIGHT SHOWERS OR SPRINKLES. COOLER TEMPS ALOFT WILL HOLD IN
PLACE LONGEST ACROSS THE NORTH COUNTY SO BETTER CHANCES FOR P-TYPE
TO START AS SNOW THEN TRANSITION TO A BRIEF MIX BEFORE GOING OVER TO
ALL LIQUID. QPF IS LESS THAN A TENTH SO NO SIGNIFICANT ACCUMULATIONS
OF EXPECTED.

TEMPERATURES WILL REMAIN WELL BELOW NORMAL FRIDAY AND FRIDAY NIGHT
WITH HIGHS AND LOWS MORE TYPICAL OF JANUARY THAN LATE NOVEMBER. THE
WARM ADVECTION WILL HELP PUSH TEMPERATURES AND EVENTUALLY DEWPOINTS
BACK ABOVE FREEZING SATURDAY AND CONTINUE RISING SATURDAY NIGHT
UNDER A BRISK SOUTHWEST FLOW. HIGHS SATURDAY WILL BE MID TO UPPER
30S PUSHING CLOSER TO 40 BY LATE SATURDAY NIGHT. THESE WARMING
TEMPERATURES WILL RIPEN THE SNOWPACK WITH MELTING QUICKLY TAKING
PLACE AFTER DEWPOINTS RISE ABOVE FREEZING.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
SUNDAY AND MONDAY A COMPLEX AREA OF LOW PRESSURE WILL LIFT THROUGH
THE WESTERN GREAT LAKES AS A MID LEVEL TROUGH DIGS INTO THE NORTHERN
PLAINS. THIS WILL FORCE STRONG HEIGHT RISES AND WARM ADVECTION
DOWNSTREAM ACROSS THE LOWER LAKES AND ALLOW TEMPERATURES TO SOAR...
WITH THE WARMEST DAY COMING MONDAY. TEMPERATURES WILL RISE INTO THE
MID 50S TO LOWER 60S...WITH DEWPOINTS IN THE MID 40S AND PLENTY OF
WIND. OVERNIGHT LOWS WILL ALSO BE MILD. THIS WILL SET THE STAGE FOR
A MAJOR MELTDOWN IN AREAS POUNDED BY LAKE EFFECT SNOW. LATEST MODEL
GUIDANCE DOES NOT SHOW AN EXCESSIVE AMOUNT OF RAIN...WITH THE BEST
RAIN CHANCES COMING ON SUNDAY NIGHT AS A WARM FRONTAL SEGMENT LIFTS
NORTH ACROSS THE AREA.

THE COMBINATION OF AT LEAST SOME RAIN AND MAJOR SNOWMELT WILL BRING
THE RISK FOR SIGNIFICANT FLOODING TO THE LAKE EFFECT AREAS...BOTH
FOR SMALL STREAMS AS WELL AS SOME OF THE LARGER CREEKS AND RIVERS.
THIS WOULD INCLUDE THE BUFFALO AREA CREEKS...CATTARAUGUS CREEK...
AND THE CREEKS THAT DRAIN THE TUG HILL REGION. IN URBAN SECTIONS
OF SOUTH BUFFALO PONDING/FLOODING MAY ALSO OCCUR AS THE LARGE
VOLUME OF MELT WATER OVERLOADS DRAINAGE SYSTEMS.

LOOKING INTO THE MIDDLE OF THE WEEK FOR THE IMPORTANT THANKSGIVING
HOLIDAY TRAVEL TIME PERIOD...COLDER AIR WILL FILTER BACK INTO THE
GREAT LAKES. BOTH THE GFS AND ECWMF DROP 850MB TEMPS TO -8C TO -10C
BY WEDNESDAY WITH CYCLONIC SOUTHWESTERLY FLOW...SUGGESTING THE
POTENTIAL FOR ANOTHER LAKE EFFECT EVENT. STAY TUNED.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
WHILE VFR CONDITIONS WILL BE IN PLACE FOR MOST AREAS EARLY THIS
MORNING THROUGH THURSDAY NIGHT...SIGNIFICANT BANDS OF LAKE EFFECT
SNOW WILL PRODUCE AREAS OF LIFR CONDITIONS.

THE LAKE EFFECT THROUGH TODAY WILL INCLUDE A BAND THAT WILL
EXTEND FROM THE CHAUTAUQUA COUNTY SHORELINE TO THE SOUTHERN HALF
OF ERIE COUNTY TO SOUTHERN GENESEE COUNTY. WHILE VFR CONDITIONS
WILL BE IN PLACE AT KIAG...THE LAKE EFFECT WILL BE JUST SOUTH OF
KROC AND KBUF FOR THE MAJORITY OF THE TIME. THERE IS A SMALL
CHANCE THE BANDS COULD DRIFT TOWARD KBUF AGAIN LATER TODAY. KJHW
SHOULD REMAIN JUST SOUTH UNTIL LATER TONIGHT...WHILE KART WILL BE
IN AND OUT OF LAKE EFFECT BANDS THROUGHOUT THE DAY...WITH
IMPROVING CONDITIONS LATER THIS EVENING.

THE CONCERN IN THE LAKE EFFECT AREAS TODAY WILL BE ACCOMPANIED BY
SOME GUSTY WINDS REGIONWIDE. SFC WINDS COULD GUST TO 35 KNOTS...
MAINLY NEAR THE LAKES AND ACROSS THE HIGHER TERRAIN.

OUTLOOK...
FRIDAY...LAKE EFFECT SNOW LIKELY EAST AND SOUTHEAST OF THE LAKES
WITH LOCAL IFR. MAINLY VFR ELSEWHERE.
SATURDAY...VFR.
SATURDAY NIGHT THROUGH MONDAY...PERIODS OF IFR/MVFR IN RAIN AND
GROUND FOG. LLWS POSSIBLE SUNDAY NIGHT AND INTO MONDAY MORNING.

&&

.MARINE...
DEEP LOW PRESSURE PASSING BY TO THE NORTH OF THE LOWER GREAT LAKES
WILL GENERATE FAIRLY STRONG WINDS TODAY INTO TONIGHT...WITH GALE
FORCE WINDS EXPECTED ON LAKE ONTARIO AND HIGH END SMALL CRAFTS ON
THE NEARSHORE WATERS OF LAKE ERIE.

THE STRONG WINDS WILL START TO SUBSIDE 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 1 AM EST FRIDAY FOR NYZ010>012-
     085.
     LAKE EFFECT SNOW WARNING UNTIL NOON EST FRIDAY FOR NYZ007-008-
     019-020.
     LAKE EFFECT SNOW WARNING FROM 4 PM THIS AFTERNOON TO 6 PM EST
     FRIDAY FOR NYZ006.
     LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR
     NYZ003.
     LAKE EFFECT SNOW ADVISORY UNTIL 4 AM EST FRIDAY FOR NYZ013.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LEZ020.
         SMALL CRAFT ADVISORY UNTIL 8 PM EST FRIDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR
         LOZ030.
         GALE WARNING UNTIL 1 AM EST FRIDAY FOR LOZ043>045-063>065.
         GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LOZ042-062.
         SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR
         SLZ022-024.

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH/ZAFF
SHORT TERM...SMITH
LONG TERM...HITCHCOCK
AVIATION...RSH/ZAFF
MARINE...RSH







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