FXUS61 KBGM 252344
AFDBGM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BINGHAMTON NY
644 PM EST FRI DEC 25 2009

.SYNOPSIS...
A STRONG AREA OF LOW PRESSURE WILL TRACK SLOWLY ACROSS THE UPPER
MIDWEST THROUGH SUNDAY. PRECIPITATION...IN THE FORM OF RAIN AND
AREAS OF FREEZING RAIN WILL OVERSPREAD THE AREA THROUGH EARLY THIS
EVENING WELL TO THE EAST OF THE STORM. THE PRECIPITATION WILL
CHANGE TO ALL RAIN LATE TONIGHT AND SATURDAY MORNING AS WARMER AIR
GRADUALLY MOVES OVER THE AREA. TEMPERATURES WILL RUN SLIGHTLY
ABOVE NORMAL SUNDAY BEFORE A DRAMATIC CHANGE TO MUCH COLDER AIR
AND LAKE EFFECT SNOW SHOWERS EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
A BAND OF PRECIPITATION CONTINUES TO MOVE NORTHEAST OVERSPREADING
THE AREA LATE THIS AFTERNOON. TEMPERATURES HAVE RISEN ABOVE
FREEZING EVERYWHERE BUT THE MOHAWK VALLEY AND PORTIONS OF THE WESTERN
CATSKILLS LATE THIS AFTERNOON... AND THE BAND APPEARS TO BE ENTIRELY IN
THE FORM OF RAIN AS IT MOVES NORTH ACROSS NORTHERN PA AND THE
CENTRAL SOUTHERN TIER OF NY. EXPECT THIS BAND TO CONTINUE TO
PRODUCE RAIN IS IT MOVES NORTHEAST ACROSS THE AREA THROUGH EARLY
THIS EVENING. HOWEVER MODEL SOUNDINGS INDICATE SLIGHT COOLING
POSSIBLE THIS EVENING AS WET BULB COOLING OCCURS IN THE ABSENCE OF
MUCH WARM ADVECTION. NAM/RUC SOUNDINGS INDICATE SLIGHT COOLING AS THE
PRECIPITATION MOVES IN EARLY THIS EVENING. THIS COULD RESULT IN
LOW ENOUGH TEMPERATURES TO ALLOW FOR SOME MIXING WITH FREEZING
RAIN OVER HIGHER ELEVATIONS FOR AWHILE. MEANWHILE... A MORE
WIDESPREAD FREEZING RAIN APPEARS LIKELY LATER THIS EVENING INTO
THE OVERNIGHT HOURS OVER THE WESTERN MOHAWK VALLEY AND WESTERN
CATSKILLS AS THE PRECIPITATION MOVES INTO PROGRESSIVELY COOLER...
DRYER AIR. THE NAM FORECAST SOUNDING EVEN INDICATES A BRIEF PERIOD
OF SNOW OR SLEET POSSIBLE AT RME LATER THIS EVENING AS THE
PRECIPITATION DEVELOPS. PRECIPITATION WILL BECOME LIGHTER AS IT
MOVES NORTHEAST INTO THE DRYER AIR LATER TONIGHT... AND ALL MODELS
INDICATE A DECREASE IN PRECIPITATION OVER THE AREA LATER TONIGHT
AFTER THE INITIAL SHOT OF ISENTROPIC LIFT MOVES OVER THE AREA THIS
EVENING.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
A SECONDARY WAVE OF LOW PRESSURE IS FORECAST TO MOVE FROM THE MID-
ATLANTIC STATES NORTH TO NEW ENGLAND ON SATRDAY... ACCOMPANIED BY
MORE PRECIPITATION. EXPECT TEMPERATURES TO BE GENERALLY WARM
ENOUGH FOR JUST RAIN WEST OF I-81 AFTER 12Z SATURDAY. FARTHER
EAST AREAS OF FREEZING RAIN WILL PROBABLY HANG ON FOR AWHILE...
WITH TEMPERATURES POSSIBLY NOT GETTING ABOVE FREEZING EVERYWHERE
IN THE CATSKILLS AND MOHAWK VALLEY UNTIL SOMETIME SATURDAY
AFTERNOON. 

THE LAST WAVE OF PRECIPITATION WILL MOVE NORTHEAST ACROSS MAINLY
THE EASTERN HALF OF THE AREA SATURDAY EVENING... FOLLOWED BY
DRYING LATE SATURDAY NIGHT. AT THIS TIME THE WAVE DOES NOT APPEAR
TO BE STRONG ENOUGH TO THROW MUCH MOISTURE BACK INTO INCREASINGLY
COOL AIR LATE SATURDAY NIGHT... SO THE MOST LIKELY SCENARIO WILL
BE FOR RAIN SHOWERS TO END BEFORE ANY CHANGE-OVER TO SNOW. 

SUNDAY LOOKS FAIRLY QUIET IN A WEAK COLD ADVECTION PATTERN BEHIND
THE CURRENT SYSTEM. THE UPPER LEVEL LOW ASSOCIATED WITH THE GREAT
PLAINS BLIZZARD WILL SWING EAST ACROSS THE AREA SUNDAY NIGHT INTO
MONDAY MORNING PROBABLY ACCOMPANIED BY SOME LIGHT SNOW OR SNOW
SHOWERS. WEAK COLD ADVECTION FOLLOWS BEHIND THAT SYSTEM MONDAY...
THEN AN ARCTIC COLD FRONT WILL CROSS THE AREA LATE MONDAY OR
MONDAY NIGHT ACCOMPANIED BY MORE SNOW SHOWERS.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
REGION WILL RESIDE IN A POST FRONTAL AIRMASS TO START THE PERIOD ON 
TUESDAY WITH BROAD NORTHWEST FLOW IN COMBINATION WITH VERY COLD H85 
TEMPS (-20C) RESULTING IN LAKE EFFECT SNOW SHOWERS DOWNWIND OF LAKE 
ONTARIO. WITH SUCH A COLD AIRMASS OVERHEAD...HIGH TEMPS ON TUESDAY 
WILL STRUGGLE TO MAKE IT OUT OF THE TEENS ACROSS MUCH OF THE AREA. 
BY TUESDAY NIGHT...H85 RIDGING AND SURFACE HIGH PRESSURE WILL MOVE 
OVERHEAD ESSENTIALLY HALTING TO ANY LINGERING LAKE EFFECT BY 
TUESDAY NIGHT.  WITH HIGH PRESSURE IN FIRM CONTROL TUESDAY 
NIGHT...OVERNIGHT LOWS WILL QUICKLY FALL INTO THE SINGLE DIGITS WITH 
SUBZERO VALUES POSSIBLE ACROSS THE TRADITIONAL COOL LOCATIONS. TEMPS 
WILL BEGIN TO MODERATE SLIGHTLY ON WEDNESDAY IN ADVANCE OF THE NEXT 
STORM SYSTEM MOVING THROUGH CENTRAL CANADA. AS THIS FEATURE 
ARRIVES...PRECIP WILL OVERSPREAD THE REGION FROM WEST TO EAST WITH 
SCATTERED SNOW SHOWERS BECOMING MORE LIKELY BY EVENING. 
GFS/ECMWF AGREE WITH THE OVERALL SYNOPTIC SET-UP HOWEVER THE ECMWF 
DELAYS PRECIP ARRIVAL UNTIL OVERNIGHT WHILE THE GFS BRINGS IT IN 
DURING THE AFTERNOON. THE SYSTEM WILL THEN SLOWLY PASS TO THE NORTH 
THROUGH THE REMAINDER OF THE PERIOD WHICH WILL MAINTAIN A THREAT FOR 
SNOW THROUGH THE CONCLUSION OF THE FORECAST. GENERALLY FOLLOWED HPC 
GUIDANCE WITH MINOR TWEAKS MAKE TO HIGH/LOW TEMP GRIDS WHEN COLDEST 
AIR IS EXPECTED TO BE OVER THE AREA.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
LOW-LEVEL SOUTHEASTERLY FLOW WILL PREVAIL THRU THE TAF PD IN
ADVANCE OF MAJOR CYCLONE IN THE UPPER MIDWEST. THE LL SE FLO WILL
CONT TO ADVECT PLENTY OF LOW-LVL MOISTURE INTO NE PA AND C NY THRU
THE PD. CIGS WERE MAINLY MVFR ATTM WITH IFR AT KBGM. I EXPECT IFR
TO BECOME MORE WIDESPREAD AS A BAND OF MAINLY RA WITH SOME FZRA
CONTS TO INCREASE IN COVERAGE OVER THE FORECAST AREA B4 6Z. I EXPECT
IFR TO PREVAIL MOST OF THE TAF PD AT KBGM AND KAVP WITH SOME IFR
EVENTUALLY MAKING IT TO KRME. IFR WILL BE SPOTTY ELSEWHERE.
CONFIDENCE LEVEL THRU 6Z FOR IFR IS HIGH AT KBGM...MEDIUM AT KAVP
AND LOW ELSEWHERE B4 6Z.

FZRA WILL PREVAIL AT KSYR AND KRME INTO THE OVERNIGHT HOURS WITH
KSYR REACHING ABV FRZG ARND 9Z AND KRME GOING ABV FRZG LAST ARND
17Z. KBGM WILL SEE A FEW PDS OF FRZA B4 6Z...AND KITH BTWN 4-8Z. 
CONFIDENCE LEVEL FOR FZRA IS HIGH AT KSYR AND KRME. KRME HAS THE
BEST SHOT FOR A PROLONGED PD OF FZRA. CONFIDENCE LVL FOR KBGM AND
KITH IS LOW TO MEDIUM. REST OF TAFS HIGH CONFIDENCE THAT NO FZRA
WILL FALL THRU THE NIGHT.

NEXT THREAT IS LLWS WHICH DVLPS AS A STRG SRLY LL JET WORKS OVR
THE REGION BETWEEN 00Z AND 09Z. THE LLWS WILL BE MOST PREVALENT AT
KRME WHERE LL ERLY WINDS ARE ADVECTING COLD DRY AIR UP THE MOHAWK
UNDER A MOIST SRLY WIND. THE COLD LL/S ARE INCREASING THE CHANCES
FOR STRG SHEAR. ADDNTLY AT KAVP LLWS WILL BE MOST PREVALENT GIVEN
THE COLD AIR ADVECTING UP THE POCONOS WHICH WILL SPILL DOWN TO
WHERE THE AIRPORT IS. THIS WILL SLOW DOWN THE LL WINDS AND
INCREASE SHEAR. CONFIDENCE IS HIGH FOR LLWS AT KAVP AND
KBGM...MEDIUM AT KITH...KBGM AND KELM AND LOW AT KSYR.

.OUTLOOK...
SAT NIGHT...MVFR/IFR IN RAIN.
SUN/MON/TUE...MVFR WITH AREAS OF LAKE EFFECT SNOW MOSTLY AT NY
SITES. 
WED...VFR.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY UNTIL 10 AM EST SATURDAY FOR 
     PAZ038>040-043-044-047-048-072.
NY...WINTER WEATHER ADVISORY UNTIL 10 AM EST SATURDAY FOR NYZ018-
     022>025-036-044-045-055-056.
     FREEZING RAIN ADVISORY UNTIL 4 PM EST SATURDAY FOR NYZ062.
     FREEZING RAIN ADVISORY UNTIL 1 PM EST SATURDAY FOR NYZ009-037-
     046-057.

&&

$$
SYNOPSIS...MSE
NEAR TERM...MSE
SHORT TERM...MSE
LONG TERM...CMG
AVIATION...DJN