Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 232029
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
329 PM EST TUE DEC 23 2014

.SYNOPSIS...
DEVELOPING LOW PRESSURE OVER THE DEEP SOUTH WILL LIFT INTO THE
LOWER OHIO VALLEY BY WEDNESDAY MORNING...BEFORE TRACKING FURTHER
NORTH TO JAMES BAY AND RAPIDLY DEEPENING WEDNESDAY AND WEDNESDAY
NIGHT. THIS SYSTEM WILL BRING OCCASIONAL SHOWERS AND UNSEASONABLY
MILD TEMPERATURES TO OUR AREA THROUGH WEDNESDAY...BEFORE ITS
TRAILING COLD FRONT PLOWS THROUGH THE REGION WEDNESDAY NIGHT. THIS
FRONT WILL BE ACCOMPANIED BY A NARROW BAND OF SHOWERS AND POSSIBLE
GUSTY THUNDERSTORMS...WITH STRONG WINDS AND A RETURN TO COLDER
TEMPERATURES THEN FOLLOWING FOR CHRISTMAS DAY. WHILE THE COLDER
WEATHER WILL ALLOW LINGERING RAIN SHOWERS TO MIX WITH SOME SNOW
CHRISTMAS DAY...LITTLE TO NO ACCUMULATION IS EXPECTED IN MOST
LOCATIONS.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
THROUGH THE FIRST HALF OF TONIGHT...EXPECT RELATIVELY QUIET WEATHER
TO PREVAIL WITH OUR REGION SITUATED IN BETWEEN TWO DYING AREAS OF
LOW PRESSURE...ONE OFF THE MID ATLANTIC COASTLINE AND ONE OVER
WISCONSIN. IN BETWEEN THESE TWO SYSTEMS...A BROAD SOUTHERLY FLOW AND
EQUALLY BROAD/DIFFUSE WARM AIR ADVECTION REGIME WILL MAINTAIN FAIRLY
WIDESPREAD CLOUD COVER AND A LOW CHANCE FOR SOME SCATTERED LIGHT
RAIN SHOWERS...THOUGH FOR THE MOST PART CONDITIONS SHOULD REMAIN
DRY.

OVERNIGHT AND WEDNESDAY...AN AREA OF LOW PRESSURE CURRENTLY GETTING
ITS ACT TOGETHER OVER THE DEEP SOUTH WILL STRENGTHEN AND LIFT ACROSS
THE OHIO VALLEY AND INTO THE CENTRAL GREAT LAKES...IN RESPONSE TO
PLENTIFUL SHORTWAVE ENERGY ROUNDING THE BASE OF THE DEEPENING
CENTRAL US LARGE-SCALE UPPER LEVEL TROUGH. AS THIS SYSTEM HEADS IN
OUR DIRECTION...WARM ADVECTION ACROSS OUR REGION WILL INCREASE...AND
THE LARGE-SCALE FLOW ALOFT WILL BECOME INCREASINGLY DIFFLUENT.
COUPLED WITH INCREASING LIFT ALONG AND AHEAD OF AN ATTENDANT WARM
FRONT...ALL OF THIS SHOULD RESULT IN SHOWERS BECOMING MORE
WIDESPREAD ACROSS OUR REGION OVERNIGHT AND INTO WEDNESDAY MORNING...
FOR WHICH HIGH-END CATEGORICAL POPS REMAIN IN PLAY. WHILE RAINFALL
AMOUNTS FROM THIS SHOULD NOT BE OVERLY SUBSTANTIAL AND ONLY ON THE
ORDER OF A TENTH TO A QUARTER OF AN INCH...MOST AREAS SHOULD STILL
SEE SOME MEASURABLE RAIN - HENCE THE VERY HIGH POPS.

LATER WEDNESDAY MORNING/WEDNESDAY AFTERNOON THE MAIN WARM FRONT WILL
LIFT OFF TO OUR NORTH AND EAST...WITH ITS TRAILING WARM SECTOR AND
ATTENDANT ZONE OF LARGE-SCALE SUBSIDENCE SPREADING NORTHEASTWARD
ACROSS OUR REGION. THIS SHOULD RESULT IN A RETURN TO RELATIVELY DRY
WEATHER DURING THIS TIME FRAME...THOUGH WITH BROAD/DIFFUSE WARM
ADVECTION STILL IN PLACE A FEW STRAY SHOWERS CANNOT BE COMPLETELY
RULED OUT. WITH THIS IN MIND...HAVE ELECTED TO DROP POPS BACK TO THE
MID-CHANCE RANGE FROM SOUTHWEST TO NORTHEAST LATER WEDNESDAY MORNING
AND AFTERNOON.

WITH RESPECT TO TEMPERATURES...THESE WILL BE UNSEASONABLY MILD
THROUGH THE PERIOD THANKS TO THE PERSISTENT WARM AIR ADVECTION
REGIME. AFTER WHAT SHOULD BE EARLY EVENING LOWS IN THE UPPER 30S TO
LOWER 40S THIS EVENING...READINGS SHOULD HOLD STEADY OR SLOWLY RISE
OVERNIGHT...WITH LOCATIONS ALONG THE LAKE ERIE SHORELINE PROBABLY
REACHING THE 50 DEGREE MARK BY DAYBREAK. FURTHER WARMING OF OUR
AIRMASS ALONG WITH THE AFOREMENTIONED DRYING TREND SHOULD THEN ALLOW
TEMPS TO REALLY SOAR ON THURSDAY...WITH MOST AREAS SEEING READINGS
CLIMB INTO THE MID AND UPPER 50S...THOUGH THE HIGHER TERRAIN WILL BE
ITS USUAL FEW DEGREES COOLER. THE WARMEST READINGS OF ALL WILL BE
FOUND ALONG THE LAKE ERIE SHORELINE NORTHEASTWARD INTO THE BUFFALO
AREA...WHERE HIGHS WILL HAVE A SHOT AT REACHING 60 THANKS TO AN
ADDED BOOST FROM A STRENGTHENING SOUTH-SOUTHEASTERLY DOWNSLOPE
FLOW...ESPECIALLY IF ANY BREAKS OF SUNSHINE CAN BE REALIZED.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
THE MAIN FOCUS THROUGH THE SHORT TERM WILL CONTINUE TO REVOLVE
AROUND A STRONG AREA OF LOW PRESSURE MOVING THROUGH THE CENTRAL
LAKES. THIS SYSTEM WILL POSE A RISK FOR DAMAGING WINDS NORTHEAST OF
THE LAKES...AND MAY EVEN PRODUCE SEVERE WEATHER.

FIRST A SYNOPTIC OVERVIEW...
A RAPIDLY DEEPENING AREA OF LOW PRESSURE WILL MOVE FROM LOWER
MICHIGAN WEDNESDAY EVENING ACROSS LAKE HURON OVERNIGHT AND REACH
WESTERN QUEBEC BY CHRISTMAS MORNING. A POWERFUL COLD FRONT TRAILING
THIS LOW WILL ENTER WESTERN NY DURING THE MID TO LATE EVENING...THEN
SWEEP EAST ACROSS THE AREA OVERNIGHT. THE LOW PRESSURE SYSTEM WILL
BE CLOSE TO THE DEFINITION OF BOMBOGENESIS...WITH 24 HOUR PRESSURE
FALLS APPROACHING 24MB. A VERY STRONG MID LEVEL TROUGH WILL SWING
THROUGH THE GREAT LAKES ON A SIMILAR TRACK AND PROVIDE A PERIOD OF
STRONG ASCENT WITHIN THE DPVA REGION ON ITS EASTERN FLANK.

RAINFALL...
DURING THE EARLY EVENING THERE MAY BE A RELATIVE LULL IN RAINFALL IN
MANY AREAS AS THE STRONGER WARM ADVECTION AND ISENTROPIC LIFT
SUPPORTED BY A 40+ KNOT LOW LEVEL JET PUSHES NORTHEAST ACROSS
NORTHERN NY AND NEW ENGLAND. THIS WILL LEAVE A GAP IN THE BETTER
FORCING UNTIL THE COLD FRONT AND MID LEVEL TROUGH ARRIVE IN WESTERN
NY BY MID EVENING. THE MAIN FORCING FOR RAINFALL WILL THEN BE STRONG
CONVERGENCE ALONG THE ADVANCING COLD FRONT AND A BRIEF AND
CONCENTRATED PERIOD OF STRONG DPVA AND UPPER LEVEL DIVERGENCE ALONG
THE ADVANCING TROUGH. STRONG PRESSURE FALLS OUT AHEAD OF THE SURFACE
LOW WILL ALSO FAVOR ASCENT GIVEN THE ASSOCIATED STRONG AGEOSTROPHIC
ADJUSTMENTS THAT OCCUR IN SUCH AN ENVIRONMENT. THE FAST MOVEMENT OF
THE COLD FRONT WILL LIMIT TOTAL RAINFALL...BUT THERE MAY BE A BRIEF
PERIOD OF DOWNPOURS ALONG THE FRONT. THE RAIN WILL QUICKLY END FROM
WEST TO EAST OVERNIGHT AS A NOTABLE DRY SLOT CROSSES THE REGION. A
FEW SHOWERS MAY MOVE BACK INTO WESTERN NY JUST BEFORE DAYBREAK
CHRISTMAS MORNING AS WRAP AROUND MOISTURE ARRIVES.

SEVERE POTENTIAL...
LATEST NAM AND GFS RUNS CONTINUE TO DROP THE SHOWALTER INDEX DOWN TO
JUST BELOW 0C WITH MUCAPE OF AROUND 100J/KG FOR PARCELS ROOTED JUST
ABOVE THE SURFACE. BY SUMMER STANDARDS THIS INSTABILITY IS
NEGLIGIBLE...HOWEVER IN THE PRESENCE OF A STRONGLY FORCED COLD FRONT
IT MAY BE ENOUGH TO SUPPORT A LINE OF CONVECTIVE SHOWERS THAT MAY
PRODUCE THUNDER. 500MB WINDS EXCEED 100 KNOTS...WHICH IS AN OLD RULE
OF THUMB THRESHOLD FOR A COLD SEASON DERECHO IF A STRONGLY FORCED
ENVIRONMENT IS PRESENT. IF SUCH A CONVECTIVE LINE IS ABLE TO
DEVELOP...THE PRESENCE OF A VERY STRONG WIND FIELD IN THE MID LEVELS
MAY SUPPORT A RISK OF CONVECTIVELY GENERATED DAMAGING WIND GUSTS.
THESE SEVERE GUSTS WOULD BE MOST LIKELY WITH ANY SMALL SCALE BOWING
SEGMENTS THAT DEVELOP ALONG THE LINE...IF IT MATERIALIZES.

WIND POTENTIAL...
THE SURFACE LOW TRACK IS VERY CLOSE TO DOWN THE MIDDLE OF OUR
CLIMATOLOGICALLY FAVORED TRACK FOR A HIGH WIND EVENT NORTHEAST OF
LAKES ERIE AND ONTARIO. A LOOK AT THE CIPS ANALOG PAGE FROM SAINT
LOUIS UNIVERSITY PULLS UP SEVERAL NOTABLE HIGH WIND EVENTS FROM THE
PAST...INCLUDING AN EVENT FROM JANUARY OF 2008 AND DECEMBER OF 2008
WHICH BOTH PRODUCED SIGNIFICANT DAMAGING WINDS AND EVEN SEVERE
WEATHER NORTHEAST OF BOTH LAKES. THE GFS REMAINS CONSISTENT IN
SHOWING AN INTRUSION OF STRATOSPHERIC AIR WITH THE DYNAMIC
TROPOPAUSE FOLDING DOWN TO AROUND 500MB WITHIN THE MID LEVEL DRY
SLOT...INDICATING STEEP MID LEVEL LAPSE RATES AND A BETTER POTENTIAL
FOR DEEP MIXING. ALL MODEL GUIDANCE CONTINUES TO SHOW THE CHANNEL OF
STRONGEST WINDS MOVING OVER LAKE ERIE AND CROSSING THE NIAGARA
FRONTIER...LAKE ONTARIO...AND SAINT LAWRENCE VALLEY.

THE NAM REMAINS STRONGER WITH WINDS ALOFT IN THE POST FRONTAL
ENVIRONMENT...WITH JUST OVER 70 KNOTS A FEW THOUSAND FEET OF THE
DECK WHILE GFS WINDS ARE IN THE 55-60 KNOT RANGE AT THAT LEVEL...
BUT EVEN THE WEAKER GFS WINDS ARE STILL SUPPORTIVE OF WARNING
CRITERIA GUSTS NORTHEAST OF THE LAKES. BUFKIT MOMENTUM TRANSFER
SCHEMES ARE ALSO SUPPORTIVE OF WARNING CRITERIA GUSTS.

GIVEN THE MODEL CONSISTENCY...ANALOG SUPPORT...AND PATTERN
RECOGNITION WE WILL UPGRADE TO A HIGH WIND WARNING FROM THE LAKE
ERIE SHORE NORTHEAST ACROSS THE NIAGARA FRONTIER TO ROCHESTER AND
ALSO IN JEFFERSON COUNTY NORTHEAST OF LAKE ONTARIO. WE HAVE
INCREASED WIND GUST POTENTIAL SOME AS WELL...WITH GUSTS UP TO 65 MPH
POSSIBLE NORTHEAST OF LAKE ERIE AND 60 MPH NORTHEAST OF LAKE
ONTARIO. THE REST OF THE CWA WILL BE FILLED IN WITH A WIND ADVISORY
WHERE GUSTS OF 50-55 MPH ARE LIKELY. WINDS WILL LIKELY OCCUR FASTER
THAN MODEL GUIDANCE WOULD SUGGEST...STARTING IMMEDIATELY AFTER THE
COLD FRONTAL PASSAGE LATER WEDNESDAY EVENING AND CONTINUING THROUGH
THURSDAY.

OTHERWISE FOR CHRISTMAS DAY EXPECT WRAP AROUND MOISTURE TO CROSS THE
AREA FROM WEST TO EAST WITH A FEW SHOWERS. THE BOUNDARY LAYER WILL
REMAIN QUITE MILD...SO EXPECT NOTHING MORE THAN A FEW WET SNOWFLAKES
TO MIX IN AT LOWER ELEVATIONS WITH NO ACCUMULATION. ACROSS THE
HIGHER TERRAIN OF THE WESTERN SOUTHERN THERE THERE MAY BE A COATING
TO AN INCH OF SLUSH FROM MORNING THROUGH EARLY AFTERNOON...WITH
SIMILAR AMOUNTS ACROSS THE HIGHER TERRAIN EAST OF LAKE ONTARIO
DURING THE AFTERNOON.

THURSDAY NIGHT ANY REMAINING SCATTERED SNOW SHOWERS EAST OF LAKE
ONTARIO WILL END AS DEEPER MOISTURE IS STRIPPED AWAY. WINDS WILL
QUICKLY DIMINISH AS THE PRESSURE GRADIENT RELAXES AND STRONGER WINDS
ALOFT EXIT. FRIDAY WILL THEN BE DRY WITH HIGH PRESSURE BUILDING
THROUGH THE MID ATLANTIC STATES. THERE MAY EVEN BE SOME SUNSHINE...
AND TEMPERATURES WILL CLIMB INTO THE 40S IN MOST AREAS AS 850MB
TEMPS RECOVER TO AROUND +2C.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
ON SATURDAY A QUICK MOVING MID LEVEL TROUGH AND COLD FRONT WILL
CROSS THE AREA DURING THE AFTERNOON. IT IS QUITE MILD AHEAD OF THIS
SYSTEM WITH HIGHS IN THE 40S AGAIN...SO ANY PRECIP WILL INITIALLY BE
RAIN SATURDAY AFTERNOON. SATURDAY NIGHT MODERATE COLD ADVECTION MAY
SUPPORT SOME VERY LIMITED LIGHT LAKE EFFECT SNOW SHOWERS EAST OF
BOTH LAKES.

SUNDAY THROUGH EARLY NEXT WEEK MODEL GUIDANCE CONTINUES TO STRUGGLE
WITH THE PATTERN...WITH BOTH THE GFS AND ECMWF SHOWING WIDE SWINGS
IN RANGES OF POSSIBILITY FROM RUN TO RUN. THE GFS IS MOST BENIGN...
WITH A WEAK WAVE PASSING WELL TO OUR SOUTHEAST SUNDAY AND EARLY
MONDAY WITH A WEAK NORTHERN STREAM TROUGH POSSIBLY BRINGING A FEW
LIGHT SNOW SHOWERS AND WEAK LAKE EFFECT. THE ECMWF BRINGS A SLOWER
SOUTHERN STREAM LOW THROUGH THE OHIO VALLEY AND INTO THE NORTHEAST
ON MONDAY...WHICH IS A FULL DAY LATER THAN ITS SOLUTION FROM
YESTERDAYS 12Z RUN. GIVEN THE UNCERTAINTY WILL JUST GO WITH A LOW
CHANCE OF SNOW SHOWERS FOR NOW UNTIL BETTER MODEL AGREEMENT AND
CONSISTENCY IS SEEN. IT DOES APPEAR TO TURN COLDER EARLY NEXT WEEK
WITH TEMPERATURES DROPPING TO NEAR...OR EVEN A LITTLE BELOW AVERAGE
BY DAY 7.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
THROUGH THE FIRST PART OF TONIGHT...EXPECT FAIRLY CLOUDY SKIES AND
SCATTERED SHOWERS TO BE THE GENERAL RULE ACROSS WESTERN AND NORTH
CENTRAL NEW YORK. ACROSS THE LOWER ELEVATIONS...CIGS WILL GENERALLY
BE VFR WITH SOME MVFR POSSIBLE AT TIMES...WHILE ACROSS THE HIGHER
TERRAIN A MIX OF IFR/MVFR CONDITIONS SHOULD IMPROVE TO MOSTLY MVFR.

OVERNIGHT AND WEDNESDAY...A STRENGTHENING AREA OF LOW PRESSURE WILL
LIFT ACROSS THE OHIO VALLEY AND INTO THE CENTRAL GREAT LAKES...WHILE
PUSHING ITS ATTENDANT WARM FRONT NORTHWARD ACROSS THE AREA. THIS
WILL RESULT IN RAIN SHOWERS BECOMING MORE WIDESPREAD FROM WEST TO
EAST OVERNIGHT AND WEDNESDAY MORNING...WITH A DIMINISHING TREND THEN
ENSUING FOR LATER WEDNESDAY MORNING AND WEDNESDAY AFTERNOON AS THE
WARM FRONT LIFTS OFF TO THE NORTH. OVERALL...EXPECT CONDITIONS TO
GENERALLY RANGE FROM MVFR TO VFR... WITH ANY MVFR MORE LIKELY ACROSS
THE HIGHER TERRAIN AND WITHIN THE SHOWERS.

AS WINDS ALOFT INCREASE A BIT TONIGHT...SOME MINIMAL LOW LEVEL WIND
SHEAR CONCERNS MAY DEVELOP FOR A TIME ACROSS THE NORTH COUNTRY AND
FAR EASTERN FINGER LAKES REGION. MORE WIDESPREAD LLWS IS THEN
EXPECTED TO DEVELOP WEDNESDAY AFTERNOON AS A STRONGER LOW LEVEL JET
WORKS INTO THE REGION.

OUTLOOK...
WEDNESDAY NIGHT...A COLD FRONT WILL CROSS THE REGION ALONG WITH A
PERIOD OF SHOWERS/POSSIBLE THUNDERSTORMS AND ATTENDANT IFR/MVFR.
STRONG WIND GUSTS ARE ALSO LIKELY TO DEVELOP...EITHER WITH OR
IMMEDIATELY FOLLOWING THE COLD FRONTAL PASSAGE.
THURSDAY...MVFR WITH SCATTERED TO NUMEROUS RAIN AND SNOW SHOWERS AND
STRONG GUSTY WINDS.
FRIDAY...MAINLY VFR.
SATURDAY...SCATTERED RAIN SHOWERS/POSSIBLE MVFR.
SUNDAY...VFR/MVFR WITH A CHANCE OF SNOW SHOWERS.

&&

.MARINE...
A MODEST SOUTHERLY TO SOUTHEASTERLY FLOW WILL PERSIST ACROSS THE
LOWER LAKES REGION TONIGHT AND WEDNESDAY MORNING AS LOW PRESSURE
OVER WISCONSIN DISSIPATES...AND AS A SECOND AND MUCH MORE
SIGNIFICANT LOW LIFTS NORTH ACROSS THE OHIO VALLEY AND TOWARD THE
CENTRAL GREAT LAKES.

THIS LATTER SYSTEM WILL RAPIDLY DEEPEN AND LIFT ACROSS THE CENTRAL
GREAT LAKES TOWARD JAMES BAY WEDNESDAY AFTERNOON AND NIGHT...WITH
ITS TRAILING COLD FRONT PLOWING ACROSS THE REGION WEDNESDAY NIGHT.
THIS FRONT WILL BE ACCOMPANIED BY A BAND OF SHOWERS AND POSSIBLE
THUNDERSTORMS WITH STRONG WIND GUSTS...WITH A PERIOD OF
SOUTHWESTERLY/WESTERLY GALES THEN HIGHLY LIKELY ON BOTH LAKES
LATER WEDNESDAY NIGHT AND CHRISTMAS DAY AS COLD AIR ADVECTION
INCREASES AND HELPS TO MIX STRONGER WINDS FROM ALOFT DOWN TO THE
SURFACE.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...HIGH WIND WARNING FROM 8 PM WEDNESDAY TO 4 PM EST THURSDAY FOR
     NYZ001>003-010>012-019-085.
     LAKESHORE FLOOD WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
     AFTERNOON FOR NYZ010-019-085.
     HIGH WIND WARNING FROM 1 AM TO 7 PM EST THURSDAY FOR NYZ007.
     WIND ADVISORY FROM 1 AM TO 7 PM EST THURSDAY FOR NYZ004>006-
     008.
     WIND ADVISORY FROM 10 PM WEDNESDAY TO 4 PM EST THURSDAY FOR
     NYZ013-014-020-021.
MARINE...GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY AFTERNOON
         FOR LEZ020-040-041.
         GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
         AFTERNOON FOR LOZ030.
         GALE WARNING FROM MIDNIGHT WEDNESDAY NIGHT TO 10 PM EST
         THURSDAY FOR LOZ043>045-063>065.
         GALE WARNING FROM 10 PM WEDNESDAY TO 4 PM EST THURSDAY FOR
         LOZ042-062.

&&

$$

SYNOPSIS...JJR
NEAR TERM...JJR
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...JJR
MARINE...JJR







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