Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 211130
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
630 AM EST SUN DEC 21 2014

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN IN PLACE TODAY WITH DRY WEATHER LASTING
INTO MONDAY. INCREASING SOUTHERLY WINDS WILL BRING A SIGNIFICANT
WARMING TREND TOWARDS THE MIDDLE OF NEXT WEEK WITH TEMPERATURES
SOARING TO WELL ABOVE AVERAGE. A STRONG AREA OF LOW PRESSURE WILL
THEN MOVE THROUGH THE CENTRAL GREAT LAKES AND PRODUCE RAIN AND GUSTY
WINDS ON WEDNESDAY FOLLOWED BY GUSTY WINDS AND A FEW LIGHT RAIN OR
WET SNOW SHOWERS FOR CHRISTMAS DAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
SURFACE RIDGE EXTENDING FROM QUEBEC TO THE SOUTHERN PLAINS
CONTINUING TO CAUSE LIGHT LOW LEVEL WIND FLOW ACROSS OUR AREA...
RESULTING PERSISTENCE OF STRATUS TRAPPED BENEATH INVERSION BASED
AROUND 3K FEET. MID LEVEL MOISTURE/LIFT ASSOCIATED WITH A WEAK
SHORTWAVE MOVING EAST ACROSS THE AREA WAS ALSO RESULTING IN SOME
FLURRIES...BUT A LAYER OF DRY AIR BETWEEN STRATUS AND MID LEVEL DECK
SHOULD PREVENT ANY MEASURABLE PRECIPITATION FROM OCCURRING.

UPPER LEVEL TROUGH CROSSING THE ROCKIES EXPECTED TO GRADUALLY
AMPLIFY OVER THE PLAINS OVER THE NEXT 24 HOURS AS STRONG WEST TO
EAST ORIENTED JET OVER THE EASTERN PACIFIC BEGINS TO OVERSPREAD
THE WESTERN CONUS. THIS WILL RESULT IN GRADUAL BACKING/INCREASE OF
LOW LEVEL FLOW ACROSS OUR AREA WHICH MAY SCOUR OUT SOME OF THE LOW
CLOUDS BY TONIGHT...BUT STILL EXPECT ANOTHER MOSTLY CLOUDY PERIOD AS
MID AND HIGH CLOUDS SHOULD ALSO BE MOVING INTO THE AREA FROM THE
WEST.

THE CLOUD COVER SHOULD RESULT IN A SMALL DIURNAL TEMPERATURE RANGE
THROUGH THE PERIOD WITH HIGHS TODAY IN THE LOWER/MID 30S AND LOWS
TONIGHT IN THE MID/UPPER 20S.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
A RIDGE OF HIGH PRESSURE SURFACE AND ALOFT WILL LIE ACROSS THE
NORTHEAST STATES THROUGH TUESDAY AS AN AMPLIFYING LONGWAVE TROUGH
DIGS ACROSS THE CENTRAL STATES. MOISTURE TRAPPED BELOW THE MID LEVEL
SUBSIDENCE INVERSION WILL CONTRIBUTE TO THE PARTLY TO MOSTLY CLOUDY
SKIES WHICH WILL PERSIST IN SPITE OF THE HIGH PRESSURE. ON MONDAY
NIGHT THROUGH TUESDAY NIGHT STRENGTHENING SOUTHERLY FLOW WILL ADVECT
INCREASING MOISTURE NORTHWARD ACROSS OUR REGION WHICH WILL REINFORCE
THE CLOUDY SKIES.

TUESDAY AND TUESDAY NIGHT WARM ADVECTION AND ISENTROPIC LIFT AHEAD
OF THE DEVELOPING SURFACE LOW OVER THE LOWER MISSISSIPPI RIVER
VALLEY WILL BRING LOW CHANCES OF A SHOWER ACROSS UPSTATE NEW YORK.
MOISTURE PROFILES DO NOT BECOME FULLY SATURATED UNTIL CHRISTMAS EVE
MORNING SO THERE WILL BE A MOISTENING FROM ALOFT TO KEEP LIGHT RAIN
SHOWERS FROM EVAPORATING ON THEIR WAY TO THE GROUND. BEST CHANCES
FOR LIGHT RAIN TUESDAY EVENING AND NIGHT WILL BE ACROSS THE SOUTHERN
TIER. SURFACE TEMPERATURES AND ESPECIALLY BOUNDARY LAYER TEMPS
SHOULD WARM SUFFICIENTLY TUESDAY NIGHT TO KEEP TEMPS WELL ABOVE
FREEZING AND AVOID THE POSSIBILITY OF A FREEZING WINTRY MIX OF
PRECIPITATION.

THE STRENGTHENING SOUTHERLY FLOW WILL KEEP OUR TEMPERATURES CLIMBING
AHEAD OF THE DEVELOPING SURFACE LOW. TEMPS WILL WARM INTO THE MID
30S TO AROUND 40 ON MONDAY. MONDAY NIGHT THROUGH TUESDAY WE WILL
CONTINUE TO SEE 850MB TEMPS INCREASE TO AROUND +10C. MOST AREAS WILL
REMAIN AT OR ABOVE FREEZING MONDAY NIGHT EXCEPT FOR THE HIGHER
ELEVATIONS THEN TEMPS PUSH WELL INTO THE 40S ON TUESDAY AND WILL
STEADY OR CONTINUE TO RISE TUESDAY NIGHT. THE STRENGTHENING
PRESSURE GRADIENT WILL BRING GUSTY WINDS ON TUESDAY AFTERNOON WITH
HIGHEST GUSTS TO NEAR 40 MPH ALONG THE LAKE ERIE SHORELINE.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
THE FORECAST FOR CHRISTMAS EVE AND CHRISTMAS DAY CONTINUES TO BE
FOCUSED ON A STORM EXPECTED TO DEVELOP OVER THE NORTHERN GULF STATES
AND SHIFT NORTH ACROSS THE GREAT LAKES. PLENTY OF UNCERTAINTY
REMAINS WITH RESPECT TO THE STRENGTH AND SPEED OF THIS STORM.

ON CHRISTMAS EVE WARM MOIST AIR WILL BE TRANSPORTED NORTH AHEAD
OF THIS STORM BRINGING RAIN AND VERY MILD TEMPERATURES TO WESTERN
AND NORTH-CENTRAL NEW YORK. NAEFS PWATS ARE FORECAST TO RISE TO NEAR
ONE INCH WHICH IS NEAR THE 99TH PERCENTILE IN A 30 YEAR PWAT CLIMO.
THIS MOISTURE COMBINED WITH THE STRONG SYNOPTIC FORCING ASSOCIATED
WITH THE LOW AND TEMPERATURES WARMING INTO THE 50S CHRISTMAS EVE
SHOULD YIELD SOME MODERATE TO OCCASIONALLY HEAVY RAIN SHOWERS. THESE
SHOWERS MAY HELP TO DRAG DOWN SOME GUSTY WINDS ASSOCIATED WITH A 50
KNOT 850MB JET STREAKING OVERHEAD.

A COLD/OCCLUDED FRONT WILL SHIFT ACROSS WESTERN AND NORTH-CENTRAL
NEW YORK WEDNESDAY NIGHT AS THE SURFACE LOW TRACKS ACROSS THE
CENTRAL GREAT LAKES. EXACT TIMING OF THE FRONTAL PASSAGE STILL NEEDS
TO BE FINE TUNED AS THE ECMWF IS ABOUT 6 HOURS FASTER THAN THE GFS.
THIS FRONT WILL BE THE LEADING EDGE TO COOLER TEMPS. IT IS IMPORTANT
TO MENTION THAT WITHOUT A STEEP RIDGE OVER THE WESTERN STATES THE
SOURCE REGION OF THIS COLD AIR WILL BE PACIFIC BASED AND NOT ARCTIC
BASED SO THIS LACK OF AN ARCTIC AIRMASS WILL BRING A REDUCED THREAT
OF ANY SIGNIFICANT SNOW THROUGH CHRISTMAS DAY. 850MB TEMPS ARE
WARMER WITH TODAYS RUNS ONLY DROP TO BETWEEN -5C AND -8C. SURFACE
TEMPS WILL ONLY FALL INTO THE MID 30S ON CHRISTMAS DAY AND LOW 30S
ACROSS THE HIGHER TERRAIN. THE LATEST FORECAST NOW REFLECTS A
RAIN/SNOW MIX ACROSS THE LAKE SHORES AND LOWER TERRAIN WITH SOME
LIMITED SNOW ACROSS THE HIGHER TERRAIN. SOME WEAK LAKE ENHANCEMENT
IS ALSO POSSIBLE PENDING AVAILABLE POST-FRONTAL MOISTURE.

ALTHOUGH THERE WAS A CONCERN OF HIGHER WINDS MIXING TO THE SURFACE
FOLLOWING THE PASSAGE OF THE COLD FRONT...00Z GFS AND ECMWF SHOW
THAT THE HIGHER WINDS ARE PREFRONTAL AND STILL ABOVE A FAIRLY STEEP
TEMPERATURE INVERSION. WINDS FOLLOWING THE COLD FRONT APPEAR TO BE
MORE WESTERLY AND WITH LESS MAGNITUDE...STILL POSSIBLE FOR A QUICK
BLAST OF GUSTY WINDS 35 TO 45 KNOTS ACCOMPANYING THE THE COLD FRONT.

BEYOND CHRISTMAS...MODELS SHOW A BRIEF PERIOD OF FAIR WEATHER
POSSIBLE ON FRIDAY AS SHORTWAVE RIDGING QUICKLY SHIFTS ACROSS THE
LOWER GREAT LAKES. FURTHER OUT WE WILL BE WATCHING NEXT WEEKEND FOR
ANOTHER POSSIBLE GREAT LAKES CUTTER STORM WHICH COULD BRING ANOTHER
ROUND OF STRONG WINDS AND MORE RAIN SHOWERS.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
PERSISTENT LOW STRATUS REMAINS IN PLACE ACROSS THE AREA. WHILE MVFR
CONDITIONS WILL BE MOST COMMON THIS MORNING...EXPECT A TRANSITION TO
VFR CONDITIONS ACROSS THE AREA DURING THE DAY.

OUTLOOK...
TONIGHT AND MONDAY...VFR.
TUESDAY...MAINLY VFR.
WEDNESDAY...MVFR WITH RAIN AND GUSTY WINDS.
THURSDAY...MVFR WITH SNOW SHOWERS AND GUSTY WINDS.

&&

.MARINE...
HIGH PRESSURE WILL REMAIN IN PLACE TODAY WITH VERY LIGHT WINDS
AND FLAT WAVE ACTION. SOUTHEAST WINDS WILL BEGIN TO INCREASE SOME ON
MONDAY BUT CONDITIONS WILL REMAIN BELOW SMALL CRAFT ADVISORY LEVELS
UNTIL AT LEAST LATER TUESDAY WHEN SOUTH TO SOUTHEAST WINDS INCREASE
FURTHER.

A DEEP AREA OF LOW PRESSURE IS THEN FORECAST TO LIFT THROUGH THE
CENTRAL GREAT LAKES WEDNESDAY THROUGH THURSDAY. THIS MAY PRODUCE A
PERIOD OF GALE FORCE WINDS ON BOTH LAKES...ESPECIALLY ON THURSDAY AS
COOLER AIR PUSHES BACK INTO THE LOWER LAKES.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...TMA
NEAR TERM...TMA
SHORT TERM...SMITH/WCH
LONG TERM...SMITH/WCH
AVIATION...TMA
MARINE...TMA




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