FXUS61 KGYX 090143
AFDGYX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
843 PM EST TUE DEC 8 2009
.SYNOPSIS...
AN OCCLUDED FRONT AHEAD OF STRONG LOW PRESSURE OVER THE MIDWEST
WILL LIFT NORTHEAST TONIGHT AND THURSDAY AND WILL PUSH NORTH OF
THE REGION WEDNESDAY NIGHT AS LOW PRESSURE MOVES INTO SOUTHERN
QUEBEC. LOW PRESSURE WILL CONTINUE TO SLOWLY LIFT NORTHEAST
THURSDAY AND FRIDAY AS HIGH PRESSURE BUILDS SOUTH OF NEW ENGLAND.
HIGH PRESSURE WILL CREST OVER THE REGION ON SATURDAY. AN ARCTIC
COLD FRONT WILL CROSS THE AREA ON SUNDAY FOLLOWED BY COLD HIGH
PRESSURE FOR MONDAY AND TUESDAY.
&&
.NEAR TERM /UNTIL 7 AM WEDNESDAY MORNING/...
845 PM...HAVE TWEAKED GRIDDED DATABASE FOR TEMPS/DEWPTS PER LATEST
OBSERVATIONS. NO OTHER CHANGES AT THIS TIME.
PREVIOUS DISCUSSION...
THE LITTLE SKIFF OF SNOW THAT
RIPPLED ACROSS NORTHERN NEW ENGLAND THIS AFTERNOON HAS PRETTY MUCH
FALLEN APART AS IT MOVES OFFSHORE. TONIGHT THERE SHOULD BE SOME
LIMITED CLEARING BEFORE THE CIRRUS FROM THE INCOMING STORM
ENVELOPS THE REGION. SNOW WILL BEGIN AFTER MIDNIGHT IN
SOUTHWESTERN NEW HAMPSHIRE AND SHORTLY AFTER DAYBREAK IN WESTERN
MAINE.
&&
.SHORT TERM /7 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
THE NAM IS NOW TRENDING COLDER IN THE
LOW LEVELS WITH THE STORM AND IS ALSO CLOSING OFF A SURFACE
PRESSURE CONTOUR NEAR THE NEW HAMPSHIRE COAST LATE WEDNESDAY. THE
GFS IS TRENDING THIS WAY BUT NOT SHOWING AS MUCH COLD AIR DAMMING
AS THE NAM. WE SUSPECT THE NAM TREND IS CORRECT BUT HAVE GONE
WITH A BLEND OF THE TWO MODELS AT THIS TIME TO MAINTAIN
CONSISTENCY. HAVE GONE GENERALLY WITH THE RIVER FORECAST CENTER QPF
FOR THIS EVENT WHICH YIELDS 1.0 TO 1.25 INCHES OF LIQUID
EQUIVALENT. INITIALLY WE ANTICIPATE HEAVY SNOWFALL RATES AS THE
VERTICAL MOTION EFFICIENTLY GENERATES AN ISOTHERMAL PROFILE TO 10
KFT. EVENTUALLY THE WARM ADVECTION WINS OUT AND BEGINS TO ERODE
THE EFFICIENT SNOW MACHINE...WITH THE CHANGEOVER TO RAIN BEGINNING
ALONG THE NEW HAMPSHIRE COAST AND SPREADING NORTHEASTWARD. TOTAL
SNOW AMOUNTS ARE EXPECTED TO RANGE FROM 3 TO 6 INCHES ALONG THE
NEW HAMPSHIRE COAST TO AS MUCH AS 10 TO 16 INCHES IN THE MOUNTAINS
BY WEDNESDAY EVENING. THE WIND WILL BE THE OTHER BIG ISSUE...WITH
MIXING SUFFICIENT TO BE ABLE TO PUNCH TO THE SURFACE NEAR THE
COAST AND ALSO AT HIGHER INLAND ELEVATIONS. EXPECTING WINDS AND
WIND GUSTS TO WARNING CRITERIA ALONG THE MID COAST OF MAINE WHERE
SUSTAINED 45 TO 50 MPH WINDS ARE LIKELY LATE WEDNESDAY AFTERNOON
BEFORE THE SECONDARY LOW PASSES INTO DOWNEAST MAINE AND THE
GRADIENT RELAXES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
PRECIPITATION WILL CUTOFF QUICKLY DURING THE EVENING HOURS WEDNESDAY
NIGHT AS OCCLUSION LIFTS NORTHEAST THROUGH THE REGION. THE EXCEPTION
WILL BE THE MOUNTAINS OF MAINE AND NEW HAMPSHIRE WHERE DEVELOPING
UPSLOPE FLOW WILL KEEP SNOW SHOWERS IN THE FORECAST WITH SOME MINOR
ADDITIONAL ACCUMULATION LIKELY. WEST TO SOUTHWEST WINDS WILL REMAIN
STRONG AND GUSTY THROUGH THE NIGHT.
LOW PRESSURE OVER SOUTHERN CANADA SLOWLY LIFTS NORTHEAST ON THURSDAY
WITH A STRONG WESTERLY GRADIENT ADVECTING COLDER AIR INTO THE REGION
THROUGH THE DAY. EXPECT HIGH TEMPERATURES IN THE MORNING THEN SLOWLY
FALLING THROUGH THE DAY. UPSLOPE SNOW SHOWERS WILL CONTINUE IN THE
MOUNTAINS WITH MINOR ADDITIONAL ACCUMULATIONS. DOWNWIND OF THE
MOUNTAINS LOOKING FOR PARTLY SUNNY SKIES.
LOW PRESSURE CONTINUES TO PULL AWAY THURSDAY NIGHT AS HIGH PRESSURE
BUILDS SOUTH OF NEW ENGLAND. THIS WILL KEEP STRONG WESTERLY GRADIENT
IN PLACE THROUGH THE NIGHT AND INTO FRIDAY ALONG WITH VARIABLE
CLOUDS AND PERSISTENT SNOW SHOWERS IN THE MOUNTAINS.
WINDS DIMINISH SOMEWHAT ON FRIDAY AS HIGH PRESSURE CRESTS OVER THE
MID ATLANTIC AND LOW PRESSURE CONTINUES TO SLOWLY PULL AWAY TO THE
NORTHEAST. LOOKING FOR A CONTINUING CHANCE OF SNOW SHOWERS INT HE
MOUNTAINS AND PARTLY SUNNY ELSEWHERE.
HIGH PRESSURE RIDGES IN FROM THE SOUTHWEST ON SATURDAY AND WESTERLY
GRADIENT FINALLY RELAXES IN THE AFTERNOON. LOOKING FOR VARIABLE
CLOUDINESS DOWNWIND OF THE MOUNTAINS AND A CONTINUING CHANCE OF SNOW
SHOWERS OR FLURRIES IN THE NORTH.
VERY CHILLY CONDITIONS SETTING UP FOR SATURDAY NIGHT AS HIGH
PRESSURE CRESTING OVER THE REGION PRODUCES GOOD RADIATIONAL
COOLING. EXPECT LOW NEAR ZERO IN THE MOUNTAINS AND IN THE TEENS IN
THE SOUTH.
SHORTWAVE FORECAST TO CROSS SOUTHERN CANADA ON SUNDAY DRAGGING A
TRAILING COLD FRONT THROUGH THE REGION AND BRINGING AN ADDITIONAL
SHOT OF ARCTIC AIR INTO THE AREA. ARCTIC FRONT WILL LIKELY SET OFF
SNOW SHOWERS AND SQUALLS AS IT CROSS THE FORECAST AREA IN THE
AFTERNOON WITH SOME MINOR ACCUMULATIONS POSSIBLE. TIGHT NORTHWEST
GRADIENT WILL HELP TO KEEP TEMPERATURES FROM FALLING AS LOW AS THEY
MIGHT AND UPSLOPE FLOW WILL KEEP SNOW SHOWERS LINGERING IN THE
MOUNTAINS THROUGH SUNDAY NIGHT.
HIGH PRESSURE BUILDS INTO THE AREA MONDAY WITH TEMPERATURES
CONTINUING WELL BELOW NORMAL.
HIGH PRESSURE WILL CREST OVER THE REGION ON TUESDAY AS ANOTHER
STRONG SHORTWAVE APPROACHES FROM THE WEST.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
SHORT TERM...NO ISSUES EXPECTED THROUGH TONIGHT UNTIL THE SNOW
BEGINS FROM SOUTHWEST TO NORTHEAST. LIFR CONDITIONS WILL BE
WIDESPREAD IN SNOW WEDNESDAY WITH STRONG WINDS...ESPECIALLY IN
COASTAL LOCATIONS. VISIBILITIES WILL IMPROVE WEDNESDAY NIGHT
THROUGH IFR CEILINGS WILL LIKELY PERSIST INTO THURSDAY MORNING.
LONG TERM...VFR THURSDAY AFTERNOON THROUGH SATURDAY. MVFR/IFR
CEILINGS/VSBY DEVELOPING ON SUNDAY AHEAD OF AN ARCTIC FRONT.
&&
.MARINE...
SHORT TERM...WINDS INCREASE TO GALES WEDNESDAY MORNING AS THE
SURFACE LOW RATCHETS UP. WINDS INCREASE TO STORM FORCE IN ANZ150
WEDNESDAY AFTERNOON AND EVENING BUT SHOULD REMAIN AT STRONG GALE
ELSEWHERE THROUGH WEDNESDAY NIGHT. 9 TO 16 FOOT SEAS BUILD
WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING IN EASTERLY FETCH BEFORE
WINDS SHIFT TO OFFSHORE AND SEAS BEGIN TO SUBSIDE.
LONG TERM...GALES POSSIBLE THURSDAY THROUGH FRIDAY AND AGAIN LATE SUNDAY.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...WINTER STORM WARNING FROM 5 AM TO 10 PM EST WEDNESDAY FOR
MEZ018.
WINTER STORM WARNING FROM 9 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR MEZ007>009-012>014-019>022-024>028.
HIGH WIND WARNING FROM 1 PM TO 10 PM EST WEDNESDAY FOR MEZ022-
026>028.
WIND ADVISORY FROM 1 PM TO 10 PM EST WEDNESDAY FOR MEZ024-025.
WINTER WEATHER ADVISORY FROM 5 AM TO 10 PM EST WEDNESDAY FOR
MEZ023.
NH...WINTER STORM WARNING FROM 5 AM TO 10 PM EST WEDNESDAY FOR
NHZ001>010-013.
WINTER WEATHER ADVISORY FROM 5 AM TO 10 PM EST WEDNESDAY FOR
NHZ014.
MARINE...GALE WARNING FROM 7 AM WEDNESDAY TO 3 AM EST THURSDAY FOR
ANZ151>154.
STORM WARNING FROM 7 AM WEDNESDAY TO 3 AM EST THURSDAY FOR
ANZ150.
&&
$$
