FXUS61 KGYX 051724
AFDGYX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
1224 PM EST SAT DEC 5 2009
.SYNOPSIS...
LOW PRESSURE FORMING OFF THE MID ATLANTIC COAST THIS AFTERNOON WILL
INTENSIFY AND MOVE TO THE NORTHEAST TONIGHT. HIGH PRESSURE WILL
BUILD TO THE SOUTH OF THE AREA SUNDAY AND MONDAY. A WEAK
DISTURBANCE WILL CROSS THE AREA LATE MONDAY AND MONDAY NIGHT. AN
AREA OF HIGH PRESSURE FOLLOWS FOR TUESDAY AND EARLY WEDNESDAY. LOW
PRESSURE WILL APPROACH FROM THE GREAT LAKES ON WEDNESDAY, THEN
REDEVELOP ALONG THE MID ATLANTIC COAST AND TRACK NORTHEAST ALONG
THE NEW ENGLAND COAST WEDNESDAY NIGHT AND EARLY THURSDAY. THIS
SYSTEM WILL GRADUALLY EXIT INTO THE MARITIMES LATE THURSDAY INTO
FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
QUICK UPDATE TO ISSUE WINTER WX ADVSRY ALG ENTIRE CSTL ZNES AND
ERN INTERIOR ZNES OF ME STARTING VRY LATE THIS AFTN THRU TNGT. LATEST
MODEL GUID CONTINUES TO SUGGEST CLOSE TO A 1/2 INCH OF QPF IN FORM
OF SNOW ALG THE IMMEDIATE CST LATE THIS AFTN THRU LATE TNGT BUT
AMTS SHARPLY DROPS OFF IN THE INTERIOR.
PREV DISCUSSION;
WEAK AREA OF HIGH PRES SLIDES ACROSS THE REGION TDA. LOW PRES
FORMS OFF THE SE COAST THIS MORNING THE TRACKS TO THE NE AND
INTENSIFIES. THIS SPREADS SN N INTO THE FCST AREA LATE TDA.
DEPENDING ON BOUNDARY LAYER TEMPS THE PRCP MAY START AS A MIX OF RN
AND SN...BUT WITH EVAPORATIONAL COOLING SHOULD QUICKLY CHANGE TO
ALL SN. WINDS PICK UP FROM THE N AS THE LOW APPROACHES. THIS WILL
BRING IN SOME DRIER AIR FROM THE N WHICH MAY SLOW DOWN ONSET OF
PRCP BUT ALSO HELP CHANGE OVER TO SN. GENERALLY USED THE GFS40
WITH A BLEND OF MAV AND MET MOS FOR TEMPS AND DEW POINTS.
&&
.SHORT TERM /SUNDAY/...
THE LOW CONTINUES TO INTENSIFY AND TRACK TO THE NE. AT THIS TIME
MODELS CONT TO SHOW THE LOW TRACKING OUTSIDE THE 40N 70W LAT/LON
BENCHMARK FOR A SIGNIFICANT SNOW EVENT FOR THE FCST AREA. MODELS
STILL VARYING IN HOW THEY HANDLE THIS EVENT BUT MOST LIKELY
SCENARIO AT THIS TIME SUGGESTS LIGHT ACCUMULATIONS OF SNOW WITH
HIGHEST AMOUNTS NEAR THE COAST AND LOWEST AMOUNTS WELL INLAND.
ACCUMULATIONS EXPECTED TO BE LESS THAN 4 INCHES AS SUPPORTED BY
HPC SNOW FCST. THUS NO HEADLINES (IN PARTICULAR A WINTER WX
ADVISORY) WILL BE ISSUED AT THIS TIME. SE NEW HAMPSHIRE IS THE
AREA THAT HAS THE BEST CHC OF REACHING WINTER WX CRITERIA OF 4 OR
5 INCHES OF SNOW. GENERALLY USED THE GFS40 WITH A BLEND OF MAV
AND MET MOS FOR TEMPS AND DEW POINTS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
LATEST AVAILABLE ECMWF AND GFS WERE IN DECENT AGREEMENT THROUGH
NEXT THURSDAY. EVOLVING PATTERN RESULTS IN A DEEP TROUGH VICINITY
OF THE FOUR CORNERS REGION WITH A CLOSED LOW SITUATED JUST WEST OF
HUDSON BAY. THE RESULTING WEST-SOUTHWEST FLOW ALOFT WILL ALLOW
ARCTIC AIR TO SEEP SOUTHWARD INTO THE NORTHEAST AND PLAINS AND
GIVE RISE TO A MAJOR DISTURBANCE IN THE FOUR CORNERS REGION BY
EARLY NEXT WEEK. EARLY INDICATIONS ARE THAT THIS SYSTEM WILL
APPROACH THE AREA BY MID WEEK WITH A TRACK AND SUBSEQUENT COASTAL
DEVELOPMENT THAT FAVORS A WINTRY MIX...CHANGING TO RAIN ALONG THE
IMMEDIATE COAST.
OTHERWISE...COLD AND RATHER QUIET THIS PERIOD WITH ONLY OTHER
SYSTEM OF NOTE A WEAK DISTURBANCE THAT MAY TOUCH OFF A FEW SNOW
SHOWERS LATE MONDAY AND MONDAY NIGHT AS IT CROSSES THE AREA.
&&
.AVIATION /17Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM /THROUGH TONIGHT/...VFR CONDITIONS LWR TO IFR AS SNOW
DEVELOPS LATE TDA AND CONTINUES THRU THE NGT. THE EXACT TRACK OF
THE OCEAN LOW WILL DETERMINE HOW MUCH SNOW FALLS AND AS A RESULT
IF CONDITIONS ONLY LWR TO MVFR (IN PARTICULAR FOR AREAS AWAY FROM
THE COAST) IF THE TRACK IS FURTHER OUT TO SEA OR IF THEY LWR TO
LIFR WITH A TRACK CLOSER TO THE COAST. N WINDS PICK UP AND BECOME
GUSTY AS WELL.
LONG TERM...MVFR POSSIBLE LATE MON AND MON NIGHT IN SNOW
SHOWERS. IFR POSSIBLE WEDNESDAY IN SNOW.
&&
.MARINE...
SHORT TERM /TODAY THROUGH TONIGHT/...NO REAL CHANGES AT THIS TIME
OTHER THAN A FEW MINOR TWEAKS. WINDS INCREASE AS OCEAN LOW
INTENSIFIES AND MOVES TO THE NE TDA AND TNGT. NORTHERLY WINDS AND
GUSTS INCREASE THRU THE SHORT TERM...REACHING SMALL CRAFT ADVISORY
OVER THE BAYS AND GALE FORCE OVER THE REST OF THE WATERS BY
MIDNIGHT TNGT...THEN CONTINUING THRU THE NGT. SEAS WILL BUILD
QUICKLY IN RESPONSE TO THE INCREASING WINDS AND APPROACHING LOW.
LONG TERM...GALE MAY LINGER SUNDAY MORNING...WITH SMALL CRAFT
WINDS AND SEAS LIKELY FOR THE BALANCE OF SUNDAY. GALE FORCE WINDS
ARE POSSIBLE WEDNESDAY.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 7 AM EST
SUNDAY FOR MEZ022>028.
NH...WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 7 AM EST
SUNDAY FOR NHZ014.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST
SUNDAY FOR ANZ151-153.
GALE WARNING FROM 10 PM THIS EVENING TO 10 AM EST SUNDAY FOR
ANZ150-152-154.
&&
$$
