FXUS61 KBGM 232347
AFDBGM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BINGHAMTON NY
647 PM EST WED DEC 23 2009
.SYNOPSIS...
LAKE EFFECT SNOW SHOWERS WILL CONTINUE ACROSS UPSTATE NEW YORK
THIS AFTERNOON AND INTO THIS EVENING. SOME FLURRIES WILL LINGER
OFF THE FINGER LAKES OVERNIGHT. ANOTHER COLD NIGHT TONIGHT WITH
TEMPERATURES DROPPING INTO THE TEENS. DRY WEATHER THURSDAY. THE
NEXT STORM SYSTEM WILL SPREAD A MIX OF SNOW AND ICE INTO THE AREA
LATE ON CHRISTMAS DAY. THIS WINTRY MIX WILL CONTINUE INTO SATURDAY
CHANGING TO RAIN.
&&
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
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 /MIDNIGHT 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 /00Z THURSDAY THROUGH MONDAY/...
LOW LEVEL MOISTURE TRAPPED UNDER AN INVERSION WILL PRODUCE MVFR
CIGS AT ALL SITES OVERNIGHT EXCEPT FOR KAVP WHERE MVFR CIGS MAY
ONLY OCCUR BTW 09Z-13Z. LINGERING SNOW SHOWERS WILL DIMINISH
TO JUST FLURRIES BY 03Z, WITH MVFR SNOW SHOWERS POSSIBLE AT
KITH/KBGM UNTIL THEN. ALSO AT KITH/KBGM, IFR CIGS ARE POSSIBLE
TOWARD DAYBREAK BETWEEN 09Z-13Z. ON THURSDAY, 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...LAKE EFFECT SNOW ADVISORY UNTIL 1 AM EST THURSDAY FOR NYZ017-
018-036-044-045.
&&
$$
SYNOPSIS...BMW
NEAR TERM...BMW
SHORT TERM...MSE
LONG TERM...RRM
AVIATION...RRM
