FXUS61 KBGM 240544
AFDBGM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BINGHAMTON NY
1244 AM EST THU DEC 24 2009
.SYNOPSIS...
WEAK LAKE EFFECT SNOW SHOWERS AND FLURRIES, WILL CONTINUE ACROSS
UPSTATE NEW YORK TONIGHT. HIGH PRESSURE WITH COLD AND DRY
CANADIAN AIR, WILL BE IN CONTROL FOR THURSDAY INTO CHRISTMAS
MORNING. A WINTER STORM WILL SPREAD A MIX OF SLEET AND ICE INTO
THE AREA LATE ON CHRISTMAS DAY. THIS WINTRY MIX WILL GRADUALLY
CHANGE TO RAIN, BUT WILL CONTINUE INTO SATURDAY.
&&
.NEAR TERM /THROUGH TODAY/...
A SFC TROF MOVG SW THROUGH THE CWA HAS LOWERED THE INVERSION
HEIGHT AND SHIFTED THE LOW LEVEL FLOW TO 320. ADDED MOISTURE FROM
LAKE HURON IS GONE. THE SHORT WAVE HAS ALSO MOVED SE WHILE 850
TEMPS HAVE RISEN. THE LAKE EFFECT BANDS HAVE DIMINISHED TO MOSTLY
FLURRIES THIS EVENING. HAVE CANCELLED THE ADVISORY. AN INCH OR
LESS OF ADDITIONAL ACCUMULATION TONIGHT.
PREVIOUS DISCUSSION...
MULTI-BAND SNOW SHOWERS CONTINUE SOUTHEAST OF LAKE
ONTARIO THIS AFTERNOON. A SHORT WAVE TROUGH IS FORECAST TO ROTATE
SOUTH AROUND THE CLOSED LOW OVER NORTHERN NEW ENGLAND THIS
AFTERNOON. THIS IS EXPECTED TO DEEPEN THE MOISTURE AND WILL RESULT
IN SEVERAL HOURS OF DEEP MOISTURE IN THE DENDRITIC SNOW GROWTH
LAYER OVER CENTRAL NY THIS AFTERNOON. THE FLOW IS FORECAST TO
REMAIN BETWEEN 300 AND 315 DEGREES WHICH WILL CONTINUE TO FAVOR
THE ZONE FROM CAYUGA TO SOUTHERN ONONDAGA...CORTLAND AND NORTHERN
CHENANGO COUNTIES. A LAKE EFFECT SNOW ADVISORY WILL CONTINUE
THROUGH THIS EVENING FOR THESE AREAS. GRADUALLY THE INVERSION
LOWERS AND THE TEMPERATURES WARM MOVING OUT OF THE DENDRITE SNOW
GROWTH LAYER. THE FLOW WILL BECOME MORE NORTHERLY FAVORING SOME
FINGER LAKE BANDS TONIGHT. UPSLOPE FLOW AND MOISTURE UNDER THE
INVERSION WILL PRODUCE SOME STRATUS. RIDGE BUILDS IN THURSDAY
DECREASING THE CLOUDS INTO THE AFTERNOON. TEMPERATURES WILL
REBOUND SOME TOWARD THE FREEZING POINT.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
HIGH PRESSURE OVER QUEBEC WILL BRING MOSTLY CLEAR... COLD WEATHER
ACROSS THE AREA ON CHRISTMAS EVE. STRONG STORM OVER THE PLAINS
WILL SPREAD CLOUDS ACROSS THE AREA ON CHRISTMAS DAY... WITH SOME
LIGHT PRECIPITATION REACHING THE SOUTHWESTERN AND CENTRAL PART OF
THE FORECAST AREA BY THE END OF THE DAY. EXPECTED SCENARIO AT THIS
TIME IS FOR TEMPERATURES TO RISE JUST ABOVE FREEZING DURING THE
AFTERNOON ON CHRISTMAS. HOWEVER... WHEN THE PRECIPITATION MOVES IN
WEST OF I-81 SOME WET BULB COOLING WILL LOWER TEMPERATURES TO NEAR
FREEZING DURING THE LATE AFTERNOON AND EVENING. BASED ON THIS AM
EXPECTING A MIX OF RAIN AND FREEZING RAIN DURING THE EVENING OVER
THE WESTERN HALF OF THE FORECAST AREA. MEANWHILE... FARTHER
EAST... PRECIPITATION WILL BE FIGHTING VERY DRY AIR ASSOCIATED
WITH THE EASTERN CANADIAN HIGH PRESSURE AS IT TRIES TO MOVE EAST.
SOME LIGHT FREEZING RAIN COULD DEVELOP EAST OF I-81 DURING THE
EARLY EVENING ON CHRISTMAS... BUT THE BETTER CHANCE FOR THOSE
AREAS WILL BE LATER AT NIGHT AS THE DRY AIR SLOWLY GIVES WAY.
TEMPERATURES IN THE MOHAWK VALLEY AND WESTERN CATSKILLS SHOULD BE
COLD ENOUGH SO THAT ANY PRECIPITATION FRIDAY NIGHT WILL BE
FREEZING RAIN. NO MODEL PROFILES ARE INDICATING ENOUGH COLD AIR
ALOFT TO SUPPORT SNOW.
FORECAST BECOMES EVEN MORE COMPLEX ON SATURDAY AS A SECONDARY AREA
OF LOW PRESSURE IS FORECAST TO DEVELOP ALONG THE MID-ATLANTIC COAST
AND MOVE NORTH TOWARD NEW ENGLAND. MODELS HAVE BEEN TRENDING
SLIGHTLY STRONGER WITH THIS SYSTEM... BUT A FAIRLY WEAK SYSTEM IS
STILL INDICATED. THE EFFECT OF THIS SYSTEM WILL BE TO PROLONG THE
CHANCE OF SATURDAY INTO SATURDAY EVENING... AND TO HELP TO LOCK
IN COLD AIR AT LOW- LEVELS OVER THE MOHAWK VALLLEY AND WESTERN
CATSKILLS. CURRENT MODEL PROFILES INDICATE THAT LOW-LEVEL
TEMPERATURES COULD REMAIN AT OR BELOW FREEZING THROUGH THE DAY
SATURDAY OVER THE MOHAWK VALLEY. BASED ON THIS HAVE MENTIONED THE
CHANCE OF FREEZING RAIN THROUGH SATURDAY. DEEP S-SE FLOW
ASSOCIATED WITH THIS SYSTEM COULD RESULT IN SOME MODERATELY HEAVY
RAIN SATURDAY INTO SATURDAY NIGHT... BUT WITH MINIMAL SNOW COVER AND
GENERALLY DRY CONDITIONS OVER THE PAST COUPLE OF MONTHS BELIEVE
THAT ANY FLOOD THREAT IS VERY LOW AT THIS TIME.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SATURDAY NIGHT PRIMARY LOW REMAINS WELL BACK ACROSS WESTERN GREAT
LAKES UNDER UPPER LEVEL CIRCULATION WHILE SECONDARY LOW MOVES
NORTHEAST INTO SOUTHERN NEW ENGLAND. DEEP ATLANTIC FETCH WILL
PROLONG PRECIP WELL INTO SATURDAY EVENING WITH LIKELY POPS ALL
AREAS. MODELS DIFFER SIGNIFICANTLY ON RATE OF CAA BEHIND SYSTEM WITH
GFS MUCH COLDER THAN ECMWF/CANADIAN GEM. WILL MENTION BOTH RAIN/SNOW
SHOWERS LIKELY THROUGH EVENING THEN CHC OF SNOW SHOWERS AS COLUMN
COOLS. SUNDAY THROUGH MONDAY, UPPER LEVEL LOW GRADUALLY LIFTS
NORTHEAST WITH GFS MUCH MORE PROGRESSIVE THAN ECMWF/GEM. WILL
CONTINUE WITH SEASONAL TEMPS AND CHC OF SNOW SHOWERS. T85 THROUGH
PERIOD ONLY DOWN TO -10C THEREFORE NOT A LOT OF LAKE RESPONSE
EXPECTED BUT WILL CARRY HIGHER POPS ACROSS NRN CWA. MONDAY NIGHT
SECONDARY TROF SWINGS THROUGH WITH MUCH COLDER AIRMASS DROPPING INTO
CWA. BY 12Z TUE T85 GENERALLY -18/-20C, RESULTING IN LOWS BOTH
MONDAY NIGHT AND TUESDAY NIGHT GENERALLY 10 TO 15 DEGREES WITH HIGHS
IN THE 20S. WILL KEEP HIGHER POPS ACROSS NRN CWA THEN FINGER LAKES
REGION AS LOW LEVEL FLOW BECOMES MORE NORTHERLY. UPPER LEVEL RIDING
ALONG WITH SFC HIGH PRES IN THE MID ATLANTIC REGION WILL PROVIDE DRY
WEATHER WEDNESDAY.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
LOW LEVEL MOISTURE TRAPPED UNDER AN INVERSION WILL PRODUCE MVFR
CIGS THROUGH DAYBREAK AT KELM/KSYR/KRME/KAVP WITH IFR CIGS LIKELY AT KBGM
AND KITH. MODEL SOUNDINGS INDICATE THAT THE DECK MAY LOWER A BIT
TOWARD DAYBREAK. MOST OF THE STIES MENTIONED ABOVE WILL REMAIN IN
THE SAME CATEGORY. HOWEVER...ACROSS THE HIGHER TERRAIN SITES OF KITH/KBGM
LIFR CIGS ARE POSSIBLE BETWEEN 09Z AND 13Z AS THE DECK
LOWERS. ON THURSDAY, IFR/MVFR CIGS WILL BE SLOW TO IMPROVE BUT
EXPECT VFR CONDITIONS AT ALL SITES BY 18Z.
NORTHWEST WINDS AROUND 10 KNOTS THIS EVENING WILL BECOME LIGHT
LATER TONIGHT THEN N/NE ON THURSDAY AROUND 5 KNOTS.
.OUTLOOK...
THURSDAY NIGHT/FRI...VFR.
FRI NGT...MVFR IN MIXED PRECIP.
SATURDAY/SATURDAY NIGHT...IFR POSSIBLE IN RAIN AND SNOW.
SUN/MON...MVFR WITH AREAS OF LAKE EFFECT SNOW AT NY SITES.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...BMW/TAC
NEAR TERM...BMW/TAC
SHORT TERM...MSE
LONG TERM...RRM
AVIATION...HEDEN/RRM
