Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 230114
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
814 PM EST MON DEC 22 2014

.SYNOPSIS...
A WEAK LOW PRESSURE SYSTEM WILL MOVE UP THE EAST COAST TONIGHT WHILE
ANOTHER LOW MOVES INTO THE CENTRAL GREAT LAKES REGION TUESDAY.  BOTH
WILL HAVE THE POTENTIAL TO BRING SOME LIGHT SHOWERS TO PORTIONS OF
THE STATE.  THEN...A MUCH STRONGER SYSTEM WILL MOVE UP THE
MISSISSIPPI VALLEY AND INTO THE CENTRAL GREAT LAKES REGION ON
WEDNESDAY...WITH ALL OF WESTERN AND CENTRAL NEW YORK SEEING RAIN
UNDER AN UNSEASONABLY WARM AIRMASS.  A COLD FRONT WILL ARRIVE FOR
CHRISTMAS DAY WITH STRONG WINDS...FOLLOWED BY SOME MORE RAIN AND
EVENTUAL SNOW SHOWERS OVER THE REGION BUT WITH LITTLE IF ANY
ACCUMULATION.

&&

.NEAR TERM /THROUGH TUESDAY/...
THE BRIEF PERIOD OF CLEARING THAT BROUGHT SUNSHINE TO THE REGION
THIS AFTERNOON HAS GIVEN WAY ONCE AGAIN TO WIDESPREAD CLOUD COVER AS
BROAD SOUTHERLY FLOW AND ASSOCIATED ISENTROPIC UPLIFT IS DEVELOPING
ACROSS THE EASTERN U.S. AHEAD OF AN AMPLIFYING UPPER LEVEL TROUGH
AND ASSOCIATED SURFACE FEATURE OVER THE MISSOURI VALLEY. THE
ADDITION OF MOISTURE FROM SOUTHEASTERLY FLOW IN THE LOWER LEVELS OF
THE ATMOSPHERE ALONG WITH A SERIES OF WEAK SHORTWAVES EJECTING OUT
OF THE OHIO VALLEY IS DRIVING AN AREA OF SHOWERS NORTHWARDS ACROSS
CTRL/ERN PA THIS EVENING. THESE SHOWERS WILL CONTINUE TO LIFT NORTH
INTO CTRL NY LATER THIS EVENING AND CURRENTLY ARE EXPECTED TO SKIRT
THE SOUTHERN TIER AND FOCUS MAINLY FROM THE GENESEE VALLEY EAST AS
THE AFOREMENTIONED UPPER LEVEL ENERGY CROSSES WRN NY AND LAKE ONTARIO
OVERNIGHT.

PRECIP TYPE FORECAST FOR TONIGHT IS A LITTLE TRICKY GIVEN THAT
SURFACE TEMPERATURES ACROSS THE SOUTHERN TIER VALLEYS AND THE NORTH
COUNTRY ARE STILL HOVERING JUST BELOW FREEZING...SUGGESTING A
POTENTIAL FOR A BRIEF PERIOD OF SLEET OR FREEZING RAIN BEFORE WARM
ADVECTION PUSHES TEMPERATURES ABOVE FREEZING. REGARDING THE SOUTHERN
TIER...MAIN AREA OF SHOWERS IS EXPECTED TO SKIRT BY JUST TO THE EAST
AND JUST CLIPPING ALLEGANY/LIVINGSTON COUNTIES AND TO A LESSER EXTENT
CATTARAUGUS COUNTY. FEEL THAT ANY FREEZING PRECIP SHOULD BE BRIEF
AND LIGHT ENOUGH TO HANDLE WITH AN SPS IF NECESSARY AND WILL NOT
PLAN TO ISSUE ANY ADVISORIES AT THIS TIME. FARTHER NORTH/EAST ACROSS
THE FINGER LAKES...TEMPERATURES ARE LARGELY ABOVE FREEZING ALREADY
AND EXPECT PRECIP TO REMAIN ALL RAIN TONIGHT. AS WITH THE SOUTHERN
TIER...THERE WILL BE A RISK FOR SLEET/FREEZING RAIN INITIALLY AS
PRECIP MOVES NORTH INTO THE AREA AFTER MIDNIGHT...BUT ONCE AGAIN IT
SHOULD BE A RACE BETWEEN WARMING SURFACE TEMPERATURES AND ONSET OF
HEAVIER SHOWERS AND WILL HOLD OFF ON ANY ADVISORIES FOR THE TIME
BEING.

AS DISCUSSED ABOVE...BROAD WARM ADVECTION WILL BE TAKING PLACE
ACROSS THE FORECAST AREA TONIGHT AND TEMPERATURES WILL REFLECT THIS
TREND WITH EARLY EVENING LOWS IN THE LOW/MID 30S GIVING WAY TO
MID/UPPER 30S BY SUNRISE. ANY LINGERING SHOWERS SHOULD ALSO BE IN
THE PROCESS OF MOVING OUT OF THE NORTH COUNTRY AROUND DAYBREAK AS THE
SHORTWAVE LIFTS ACROSS THE OTTAWA/ST. LAWRENCE VALLEYS...GIVING WAY
TO WHAT BE A MAINLY DRY MORNING ACROSS THE AREA. WITH LARGE SCALE
WARM ADVECTION/ISENTROPIC UPLIFT ONGOING ACROSS THE REGION...EXPECT
PLENTY OF CLOUD COVER TO REMAIN ACROSS THE AREA THROUGHOUT THE DAY
HOWEVER WITH A CHANCE OF SHOWERS RETURNING BY THE AFTERNOON AS
ANOTHER MID-LEVEL SHORTWAVE SWINGS ACROSS THE REGION. WARM ADVECTION
WILL PUSH TEMPERATURES INTO THE MID TO UPPER 40S BY THE AFTERNOON
HOURS.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
PERSISTENT LOW/MID LEVEL WARM ADVECTION AND UPPER LEVEL DIVERGENCE
TUESDAY NIGHT WILL CONTINUE TO PRODUCE A WEALTH OF CLOUD COVER AND
AT LEAST A FEW SCATTERED SHOWERS. THE INITIAL SERIES OF WEAK LEAD
MID LEVEL SHORTWAVES WILL LIFT INTO QUEBEC OVERNIGHT WITH ANY
ORGANIZED SHOWERS FOLLOWING. TOWARD WEDNESDAY MORNING A RENEWED PUSH
OF STRONGER WARM ADVECTION WILL MOVE INTO THE WESTERN SOUTHERN TIER
WITH SHOWERS BECOMING MORE WIDESPREAD. IT WILL REMAIN QUITE MILD
WITH LOWS IN THE LOWER TO MID 40S IN MOST AREAS. THESE LOWS ARE
LIKELY TO OCCUR EARLY...WITH TEMPERATURES BECOMING EVEN WARMER BY
WEDNESDAY MORNING.

ON WEDNESDAY A STRONG PUSH OF WARM ADVECTION AND UPPER LEVEL
DIVERGENCE WILL PRODUCE A PERIODS OF RAIN ACROSS THE ENTIRE REGION.
THE BROAD AREA OF ASCENT WILL BE ENHANCED BY SEVERAL MID LEVEL
VORTICITY MAXIMA CROSSING THE REGION DOWNSTREAM OF THE MAIN MID
LEVEL TROUGH. A PLUME OF DEEP MOISTURE WILL BE CAPTURED AND SPREAD
NORTHWARD BY THIS SYSTEM WITH PWAT RISING TO AROUND 1.25
INCHES...WHICH IS OVER 3 STANDARD DEVIATIONS ABOVE AVERAGE AND NEAR
THE MAX OBSERVED FOR LATE DECEMBER. DESPITE THE COPIOUS AMOUNTS OF
MOISTURE...IT DOES NOT APPEAR THERE WILL BE ENOUGH OF A FOCUS WITHIN
THE BROAD WARM ADVECTION REGIME TO PRODUCE EXCESSIVE RAINFALL IN ANY
ONE LOCATION. MAX RAINFALL AMOUNTS SHOULD FOCUS IN AREAS FAVORED BY
UPSLOPE SOUTHERLY FLOW...SUCH AS THE SOUTHERN TUG HILL PLATEAU WHERE
RAIN AMOUNTS MAY EXCEED 1 INCH. ELSEWHERE EXPECT AROUND A HALF INCH
TOTAL ACROSS LOWER ELEVATIONS AND 3/4 INCH ACROSS THE HIGHER TERRAIN
OF THE SOUTHERN TIER AND FINGER LAKES.

WEDNESDAY NIGHT A STRONG COLD FRONT WILL CROSS THE REGION AND
PRODUCE ONE LAST PERIOD OF RAIN FORCED BY STRONG MID LEVEL HEIGHT
FALLS AND LOW LEVEL CONVERGENCE ALONG THE FRONTAL ZONE. THE
SHOWALTER INDEX DROPS TO JUST BELOW ZERO ALONG THE FRONT...SO THERE
MAY EVEN BE A FEW SCATTERED THUNDERSTORMS. GIVEN THE VERY STRONG
WIND FIELD ASSOCIATED WITH THE SYSTEM ANY THUNDERSTORM THAT DOES
FORM MAY PRODUCE GUSTY WINDS. RAIN WILL QUICKLY END FROM WEST TO
EAST OVERNIGHT WITH THE PASSAGE OF THE SURFACE COLD FRONT...WITH A
NOTABLE MID LEVEL DRY SLOT CROSSING THE REGION IMMEDIATELY BEHIND
THE FRONT.

THE MAIN CONCERN WITH THIS SYSTEM CONTINUES TO REVOLVE AROUND WIND
WITH SOME POTENTIAL FOR DAMAGING WINDS NORTHEAST OF LAKES ERIE AND
ONTARIO. A SURFACE LOW WILL RAPIDLY DEEPEN AS IT MOVES FROM THE
LOWER OHIO VALLEY ACROSS MICHIGAN LATE WEDNESDAY BEFORE REACHING
WESTERN QUEBEC BY CHRISTMAS MORNING. THIS IS A CLIMATOLOGICALLY
FAVORED TRACK TO PRODUCE STRONG WINDS NORTHEAST OF LAKES ERIE AND
ONTARIO WHERE WINDS ARE CHANNELLED BY THE LAKES AND TERRAIN. THE
LATEST GFS CONTINUES TO SUPPORT A MODERATE INTRUSION OF
STRATOSPHERIC AIR WITH THE DYNAMIC TROPOPAUSE FOLDING DOWN TO AROUND
500MB...SUGGESTIVE OF DEEPER MID LEVEL INSTABILITY AND MIXING IN THE
DRY SLOT BEHIND THE COLD FRONT. THE BEST ISALLOBARIC FALL/RISE
COUPLET IS STILL FORECAST TO PASS THROUGH THE CENTRAL LAKES...BUT
MODERATE PRESSURE RISES ON THURSDAY WILL STILL AID IN DOWNWARD
MOMENTUM TRANSFER.

MODEL GUIDANCE CONTINUES TO SHOW SOME RUN TO RUN VARIANCE WITH
RESPECT TO THE EXACT TRACK AND STRENGTH OF THE LOW...AND ALSO A GOOD
DEAL OF RUN TO RUN DIFFERENCES WITH WIND SPEEDS ALOFT. THE LATEST
12Z GFS TRENDED A LITTLE FASTER AND SLIGHTLY WEAKER WITH THE SURFACE
LOW AND NOTABLY WEAKER WITH WINDS ALOFT...ALTHOUGH PROBABLY STILL
JUST STRONG ENOUGH TO PRODUCE 45-50 KNOT GUSTS NORTHEAST OF THE
LAKES. GIVEN THAT THIS IS STILL ALMOST 3 DAYS AWAY AND WE ARE STILL
SEEING RUN TO RUN MODEL DIFFERENCES...WILL HOLD OFF ON A HIGH WIND
WATCH FOR NOW. IT APPEARS THE STRONGEST WINDS WILL OCCUR FROM LATER
WEDNESDAY NIGHT THROUGH THE FIRST HALF OF CHRISTMAS DAY ACROSS
WESTERN NY NORTHEAST OF LAKE ERIE...AND A FEW HOURS LATER NORTHEAST
OF LAKE ONTARIO.

OTHERWISE ON CHRISTMAS DAY A BRIEF PERIOD OF WRAP AROUND MOISTURE
WILL CROSS THE LOWER LAKES. THERE IS A DISTINCT LACK OF COLD AIR
BEHIND THIS SYSTEM WITH 850MB TEMPS ONLY DROPPING TO AROUND -6C BY
THE END OF THE DAY. THIS WILL ONLY SUPPORT A FEW WET SNOWFLAKES
MIXING IN WITH THE RAIN AT LOWER ELEVATIONS...WITH HIGHER TERRAIN
PROBABLY CHANGING OVER TO ALL WET SNOW. COULD SEE SOME MINOR LESS
THAN AN INCH ACCUMULATIONS ON THE HILLS...WITH NO ACCUMULATION
ACROSS LOWER ELEVATIONS. IT IS NOT EVEN CLOSE TO COLD ENOUGH FOR ANY
LAKE RESPONSE. TEMPERATURES WILL START OFF IN THE 40S IN MOST AREAS
AT DAYBREAK THEN FALL INTO THE MID TO UPPER 30S THROUGH THE DAY. IT
WILL NOT BE A WHITE CHRISTMAS THIS YEAR IN WESTERN NY.

ANY LINGERING LIGHT SNOW SHOWERS EAST OF THE LAKES CHRISTMAS EVENING
WILL END OVERNIGHT AS A RIDGE OF HIGH PRESSURE BUILDS TOWARDS THE
LOWER LAKES AND ANY REMAINING MOISTURE IS STRIPPED AWAY.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
ON FRIDAY HIGH PRESSURE WILL BUILD THROUGH THE MID ATLANTIC WITH A
RIDGE EXTENDING NORTH INTO THE LOWER LAKES AND PROVIDING A DRY DAY
WITH EVEN A GOOD CHANCE AT SOME SUNSHINE. WHAT LITTLE COOL AIR
BRIEFLY ENTERS THE REGION ON CHRISTMAS DAY WILL BE GONE AS WARM
ADVECTION BRINGS 850MB TEMPS TO AROUND +2C. THIS WILL SUPPORT HIGHS
BACK INTO THE 40S...A GOOD 10 DEGREES ABOVE AVERAGE. ON SATURDAY A
FAST MOVING MID LEVEL TROUGH WILL SWING THROUGH THE GREAT LAKES AND
QUEBEC. THIS MAY PRODUCE A FEW RAIN SHOWERS MIXING WITH WET SNOW
LATER IN THE DAY AS MODERATE COLD ADVECTION BEGINS. IT MAY BECOME
MARGINALLY COLD ENOUGH FOR SOME LIMITED LAKE EFFECT BY SATURDAY
NIGHT EAST OF THE LAKES.

MODELS DIVERGE SIGNIFICANTLY BY SUNDAY. THE 12Z ECMWF REMAINS
CONSISTENT WITH PREVIOUS RUNS IN TAKING A STRONG SOUTHERN STREAM
TROUGH THROUGH THE OHIO VALLEY AND INTO THE NORTHEAST...WITH A
FRONTAL WAVE SPREADING A BAND OF ACCUMULATING SNOW ACROSS OUR
REGION. THE GFS REMAINS CONSISTENT WITH ITS PREVIOUS RUNS IN KEEPING
ANY SEMBLANCE OF THIS WAVE SUPPRESSED FAR TO THE SOUTHEAST WITH A
WEAK WAVE RUNNING THROUGH THE SOUTHEAST STATES. THE CANADIAN GEM IS
CLOSER TO THE ECMWF SOLUTION THROUGH SATURDAY. FOR NOW WILL HEDGE
TOWARDS THE ECMWF SCENARIO AND PLACE A CHANCE OF SNOW INTO THE
FORECAST FOR SUNDAY AND SUNDAY NIGHT. BOTH THE GFS AND ECMWF THEN
SUGGEST A MAINLY DRY MONDAY AS HIGH PRESSURE BUILDS INTO THE
NORTHEAST.

&&

.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
VFR CIGS ACROSS THE FORECAST AREA WILL LOWER TO MVFR ACROSS PORTIONS
OF CTRL/NCTRL NY BY 06Z AS INCREASING LOW-LEVEL MOISTURE AND LIFT
ARRIVE FROM THE SOUTH. AN AREA OF -SHRA MOVING NORTH OUT OF PA WILL
ACCOMPANY THESE LOWER CIGS WITH A FEW ISOLATED AREAS OF
IP/-FZRA...MAINLY ACROSS HIGHER TERRAIN OF THE SOUTHERN TIER AND THE
NORTH COUNTRY DEVELOPING BRIEFLY BEFORE CHANGING OVER TO -SHRA AS
WARMER AIR SURGES NORTHWARDS ACROSS THE AREA. ANY FREEZING PRECIP IS
NOT EXPECTED TO IMPACT FCST TERMINALS.

THE UPPER LEVEL DISTURBANCE THAT WILL BE AIDING IN THE DEVELOPMENT
OF THE PRECIP ACROSS THE AREA TONIGHT WILL LIFT OFF TO THE NORTHEAST
ACROSS THE ST. LAWRENCE VALLEY LATE TONIGHT WITH PRECIP TAPERING OFF
ACROSS THE NORTH COUNTRY AFTER 12Z. OTHERWISE ANY LINGERING MVFR
CIGS WILL IMPROVE TO VFR CIGS TUE MORNING...MAINLY AFTER 10-12Z.

OUTLOOK...
WEDNESDAY...MOSTLY MVFR AND SOME -SHRA.  SOME GUSTY WINDS.
WEDNESDAY NIGHT...MVFR/IFR WITH -SHRA.
THURSDAY...MVFR WITH -SHRA/-SHSN AND GUSTY/STRONG WINDS.
FRIDAY...MAINLY VFR.
SATURDAY...POSSIBLE MVFR CONDITIONS WITH SCT SHSN.

&&

.MARINE...
A WEAK LOW WILL MOVE UP THE EAST COAST TONIGHT AND FALL APART WHILE
A SECOND LOW MOVES INTO THE CENTRAL GREAT LAKE REGION AND SIMILARLY
WEAKENS ON TUESDAY.  ON WEDNESDAY...A MUCH STRONGER AND DEEPENING
SYSTEM WILL MOVE UP THE MS VALLEY AND INTO THE CENTRAL GREAT
LAKES...WITH SMALL CRAFT AND EVENTUALLY GALE FORE POTENTIAL WINDS
LATE WEDNESDAY NIGHT AND THURSDAY OVER LAKE ERIE.  GALE FORCE WINDS
ARE ALSO POSSIBLE ON LAKE ONTARIO LATER THURSDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...GALE WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
         AFTERNOON FOR LEZ040-041.

&&

$$

SYNOPSIS...ZAFF
NEAR TERM...WOOD
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...WOOD
MARINE...ZAFF







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