Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 231129
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
629 AM EST TUE DEC 23 2014

.SYNOPSIS...
A WEAK LOW PRESSURE AREA WILL MOVE INTO THE CENTRAL GREAT LAKES
TODAY WITH SCATTERED RAIN SHOWERS EMBEDDED WITHIN THE REGION OF WARM
ADVECTION ACROSS THE AREA. A MUCH STRONGER SYSTEM WILL THEN MOVE UP
THE MISSISSIPPI VALLEY AND INTO THE CENTRAL GREAT LAKES REGION ON
WEDNESDAY...WITH ALL OF WESTERN AND CENTRAL NEW YORK SEEING RAIN
WITHIN 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 TONIGHT/...
A SMALL REGION OF COLD AIR REMAINS ACROSS THE NORTHERN PORTIONS OF
JEFFERSON AND LEWIS COUNTIES. WILL HAVE A FREEZING RAIN ADVISORY FOR
THAT AREA THROUGH 10AM. TEMPERATURES ARE ABOVE FREEZING ELSEWHERE
ACROSS THE FORECAST AREA.

A BROAD REGION OF WARM AIR ADVECTION ACROSS NEW YORK STATE HAS BEEN
BRINGING INCREASINGLY WARM AND MOIST AIR TO THE FORECAST AREA. THIS
IS RESULTING IN SCATTERED RAIN SHOWERS ACROSS THE AREA...DRIER AIR
NEAR THE SURFACE IS ERODING THE AMOUNT OF RAIN THAT ACTUALLY REACHES
THE SURFACE BUT HIGHER DEWPOINTS WILL BE REALIZED AS THE WARM
ADVECTION CONTINUES TODAY AND TONIGHT. TEMPERATURES WILL BE ON THE
RISE EARLY THIS MORNING AND TODAY...EVEN STEADY OR RISING DURING
TONIGHT.

THE DRIVING FORCE BEHIND THE WARM ADVECTION IS AN AREA OF LOW
PRESSURE ACROSS THE MIDWESTERN STATES...MOVING TOWARD THE CENTRAL
GREAT LAKES. THE CENTER OF THIS LOW WILL WEAKEN AND FILL ACROSS THE
GREAT LAKES BUT WILL LEAVE A BROAD AREA OF CYCLONIC CIRCULATION
WHICH WILL MAINTAIN THE SOUTHEAST TO SOUTHERLY WINDS AND THUS THE
WARM ADVECTION. EXPECT TO ENCOUNTER SCATTERED SHOWERS THROUGH THE
DAY AND THIS EVENING...BECOMING MORE NUMEROUS TONIGHT AS ANOTHER
REGION OF LOW PRESSURE MOVES NORTHWARD FROM THE MISSISSIPPI VALLEY.

HIGH TEMPERATURES TODAY WILL BE IN THE UPPER 30S TO LOWER 40S ACROSS
THE NORTH COUNTRY WITH MIDDLE 40S ACROSS THE REST OF THE FORECAST
AREA. LOWS TONIGHT WILL OCCUR EARLY WITH READINGS IN THE LOWER 40S
ACROSS THE REGION...THEN LIKELY RISING TEMPERATURES OVERNIGHT.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
THE FOCUS FOR THIS PERIOD CONTINUES TO BE ON THE IMPACTS ASSOCIATED
WITH STRONG CYCLOGENESIS CHRISTMAS EVE AND CHRISTMAS DAY. STRONG
UPPER LEVEL JET OF NEAR 175 KNOTS SAMPLED LAST EVENING BY THE 00Z
SALT LAKE CITY UTAH RAOB WILL AMPLIFY THE CENTRAL CONUS LONGWAVE
TROUGH ALREADY IN PLACE. STRONG ENERGY ROUNDING THE BASE OF THE
TROUGH WILL LIFT NORTHWARD...BECOMING NEGATIVELY TILTED AND CLOSING
OFF BY WEDNESDAY. ASSOCIATED SURFACE CYCLOGENESIS WILL TAKE
ADVANTAGE OF A PREEXISTING BAROCLINIC ZONE...DEEPENING SOME 18 TO 20
MB FROM 12Z WEDNESDAY TO 06Z THURSDAY...AS IT LIFTS FROM THE
SOUTHERN US TOWARD THE EASTERN GREAT LAKES.

SECOND WAVE OF RAIN SHOULD ALREADY BE INTO THE REGION AS WE START
THE PERIOD...AS THE SECONDARY WAVE STRENGTHENS SOUTH OF THE REGION.
THE WELL ADVERTISED MODEL DISCREPANCIES WITH THIS WAVE CAUSING THIS
FORECASTER HEADACHES. HOWEVER...THERE DOES FINALLY SEEM TO BE SOME
MODEL CONSENSUS EMERGING WITH THE 00Z MODEL SUITE. THE CONSENSUS
TRACK OFFERED BY THE 00Z GFS/ECMWF/CANADIAN TAKES THE STRENGTHENING
SURFACE LOW FROM AROUND MIDDLE TENNESSEE AT 12Z WEDNESDAY...
NORTHWARD TO LAKE HURON BY AROUND 06Z THURSDAY...KEEPING IT WEST OF
WESTERN NEW YORK. DESPITE THIS EMERGING CONSENSUS...THERE ARE STILL
DIFFERENCES IN THE TIMING AND STRENGTH OF THE SURFACE LOW.

PLENTIFUL GULF MOISTURE WILL ADVECT INTO THE REGION WEDNESDAY WITH
PRECIPITABLE WATER VALUES TO OVER AN INCH...SOME 4 TO 5 STANDARD
DEVIATIONS ABOVE NORMAL FOR THIS TIME OF YEAR. LIFT WILL INCREASE AS
WELL DUE TO SYSTEM-RELATIVE ISENTROPIC ASCENT. THE RESULT WILL BE A
WET AND VERY MILD CHRISTMAS EVE WITH THE SURFACE LOW TRACKING TO THE
WEST OF THE AREA.

WEDNESDAY NIGHT...A STRONG COLD FRONT IS STILL EXPECTED TO PLOW
ACROSS ACROSS THE REGION. THERE IS SOME CONCERN FOR A NARROW COLD
FRONTAL CONVECTIVE LINE WHICH COULD CAUSE SOME ENHANCED WIND SPEEDS
AS IT MOVES THROUGH. BEHIND THE FRONTAL PASSAGE...THE RAIN WILL
QUICKLY END FROM WEST TO EAST AS A SHARP DRY SLOT SURGES INTO THE
REGION. THE MAIN CONCERN WITH THIS SYSTEM CONTINUES TO BE THE
POTENTIAL FOR STRONG AND POSSIBLY DAMAGING POST COLD FRONTAL WINDS
NORTHEAST OF LAKES ERIE AND ONTARIO. THE TRACK AND FORECAST
DEEPENING OF THE LOW AS IT MOVE TO THE WEST AND THEN TO THE NORTH OF
THE AREA IS A CLIMATOLOGICALLY FAVORED TRACK TO PRODUCE STRONG WINDS
NORTHEAST OF LAKES ERIE AND ONTARIO...WHERE WINDS ARE CHANNELLED BY
THE LAKES AND TERRAIN. CONFIDENCE IN THESE AREAS IS HIGH ENOUGH AT
THIS POINT TO GO AHEAD AND ISSUE A HIGH WIND WATCH FOR THE LATE
WEDNESDAY NIGHT THROUGH THURSDAY TIME FRAME. IT SHOULD BE NOTED THAT
THE TOP 15 CIPS ANALOGS VALID AT 60 HOURS SHOWING MULTIPLE AREAWIDE
HIGH WIND REPORTS. WHETHER THIS IS ASSOCIATED WITH A CONVECTIVE LINE
OR GRADIENT WINDS IS NOT KNOWN...BUT DOES GIVE A BIT MORE CONFIDENCE
FOR THE POTENTIAL OF HIGH WINDS IN THE AREA OUTLINE IN THE WATCH AND
EVEN THE FURTHER THOUGHT OF POSSIBLE EXPANSION TO OTHER AREAS IN
LATER FORECASTS.

THE COLD SECTOR AIR MASS WILL INFILTRATE THE AREA CHRISTMAS DAY WITH
THE PRECIPITATION CHANGING OVER TO WET SNOW AS THE LOW MOVES OFF TO
THE NORTH. 850 MB TEMPERATURES ONLY FALLING TO AROUND -5C/-6C WHICH
WILL BE TOO WARM FOR MUCH OF A LAKE RESPONSE. THEREFORE...WHATEVER
SNOW ACCUMULATION WE GET WILL BE WITHIN THE WRAP AROUND MOISTURE.
THIS MOVES THROUGH RATHER QUICKLY...SO EXPECT LITTLE IF ANY SNOW
ACCUMULATION FOR MOST OF THE AREA...WITH THE POTENTIAL FOR AN INCH
ON THE HIGHER TERRAIN.

ANY LINGERING LIGHT SNOW SHOWERS CHRISTMAS NIGHT WILL END OVERNIGHT
AS A RIDGE OF HIGH PRESSURE BUILDS TOWARDS THE LOWER LAKES AND ANY
REMAINING MOISTURE IS STRIPPED AWAY. WINDS WILL ALSO BE DIMINISHING
FAIRLY QUICKLY.

&&

.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 /12Z TUESDAY THROUGH SATURDAY/...
A SMALL AREA NEAR THE SAINT LAWRENCE RIVER IS JUST BELOW FREEZING
AND HAD BEEN EXPERIENCING SOME LIGHT FREEZING RAIN...OTHERWISE
TEMPERATURES ARE ABOVE FREEZING ELSEWHERE WITH ONLY SCATTERED
SHOWERS ACROSS THE REST OF THE REGION.

EXPECT MAINLY VFR CEILINGS TODAY WITH SOME MVFR CIGS ACROSS THE
SOUTHERN TIER AND EASTERN LAKE ONTARIO REGION. THE SOUTHERN TIER MAY
HAVE IFR CIGS EARLY IN THE MORNING...IMPROVING TO MVFR BY 14Z.

AS LOW PRESSURE FORMS OVER THE SOUTHERN MISSISSIPPI VALLEY...THE
LIKELIHOOD OF RAIN WILL INCREASE LATER IN THE DAY AND
EVENING...ESPECIALLY FOR THE WESTERN TAF SITES.

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 INTO THE CENTRAL GREAT LAKE REGION AND WEAKEN
TO AN OPEN TROUGH TODAY.  ON WEDNESDAY...A MUCH STRONGER AND
DEEPENING SYSTEM WILL MOVE UP THE MISSISSIPPI VALLEY AND INTO THE
CENTRAL GREAT LAKES...WITH SMALL CRAFT AND EVENTUALLY GALE FORCE
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...FREEZING RAIN ADVISORY UNTIL 10 AM EST THIS MORNING FOR NYZ007-
     008.
     HIGH WIND WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
     EVENING FOR NYZ007.
     HIGH WIND WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
     AFTERNOON FOR NYZ001-002-010-011-019-085.
MARINE...GALE WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
         AFTERNOON FOR LEZ040-041.
         GALE WATCH FROM THURSDAY MORNING THROUGH THURSDAY
         EVENING FOR LOZ043>045-063>065.
         GALE WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
         EVENING FOR LOZ042-062.

&&

$$

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







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