FXUS61 KBOX 120940
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
440 AM EST SAT DEC 12 2009
.SYNOPSIS...
LARGE LOW PRES OVER EASTERN CANADA WILL CONTINUE TO GENERATE BLUSTERY AND
UNSEASONABLY COLD WEATHER ACROSS SOUTHERN NEW ENGLAND TODAY. A WEAK WAVE
OF LOW PRESSURE AND ASSOCIATED FRONT WILL PUSH ACROSS THE REGION
SUNDAY AFTERNOON AND NIGHT...BRINGING MAINLY RAIN TO THE AREA. WEAK HIGH
PRESSURE FOLLOWS MON PROVIDING DRY AND SEASONABLY WARM WEATHER BEFORE
ANOTHER ROUND OF PRECIPITATION ARRIVES LATE MONDAY NIGHT AND TUESDAY.
BLUSTERY AND COLDER THAN NORMAL WEATHER RETURNS MID TO LATE NEXT WEEK.
&&
.NEAR TERM /UNTIL 2 PM THIS AFTERNOON/...
ANOTHER UNSEASONABLY COLD DAY IS ON TAP FOR SOUTHERN NEW ENGLAND...AS
850 MB TEMPS HOVER AROUND -16C. DESPITE PLENTY OF SUNSHINE THESE
TEMPS ALOFT WILL ONLY PROVIDE HIGHS TODAY IN THE MID TO UPPER 20S
WITH LOW 30S IN THE COASTAL PLAIN...INCLUDING BOSTON - PROVIDENCE
CORRIDOR. HIGHS WERE DERIVED FROM THE COOLER METNAM WHICH HAS BEEN
OUTPERFORMING THE WARMER GFS MOS IN THIS COLD REGIME.
GUSTY WEST WINDS OF 25-35 MPH WILL CONTINUE AND JUST ADD TO THE COLD
CONDITIONS BY PROVIDING WIND CHILLS IN THE TEENS INLAND AND LOW 20S
IN THE COASTAL PLAIN. IT COULD BE MUCH WORSE...AS ON THIS DATE BACK
IN 1992 /DEC 11-12/ A POWERFUL NOREASTER AFFECT MUCH OF THE NORTHEAST
WITH HEAVY SNOW/RAIN/DAMAGING WINDS AND MAJOR COASTAL FLOODING.
&&
.SHORT TERM /2 PM THIS AFTERNOON THROUGH 6 PM SUNDAY/...
TONIGHT...
COLD NIGHT AHEAD /ESPECIALLY OUTSIDE OF THE URBAN AREAS/ AS WINDS
DIMINISH...CLEAR SKIES AND A VERY DRY AIRMASS ALLOW TEMPS TO PLUMMET
AFTER SUNSET. DEPENDING ON HOW THICK CIRRUS CANOPY IS LATER TONIGHT
TEMPS MAY LEVEL OFF SECOND HALF OF THE NIGHT. NEVERTHELESS A COLD
NIGHT AHEAD.
SUNDAY...
AFTER SOME MORNING SUNSHINE CLOUDS WILL BE ON THE INCREASE AS MID
LEVEL TROF AND ASSOCIATED FRONT APPROACH FROM THE OH VLY. MODELS
INCLUDING THE GFS/NAM AND 03Z SREF ARE IN GOOD AGREEMENT ON THE
TIMING OF THE ONSET OF PRECIP...WITH ARRIVAL TIME AROUND 18Z CT RVR
VLY TO 21Z EASTERN MA. SURFACE HIGH SLIDES SOUTHEAST OF NEW ENGLAND
SUNDAY...SO RETURN SOUTHERLY FLOW WILL QUICKLY ERODE COLD AIR/WARM
BOUNDARY LAYER ESPECIALLY ACROSS THE COASTAL PLAIN OF RI AND MA.
THEREFORE EXPECTING PTYPE TO BE RAIN ACROSS THIS AREA. THE ONLY
EXCEPTION WILL BE ACROSS NORTHWEST MA INTO SOUTHWEST NH WHERE
THE BOUNDARY LAYER WILL TAKE A BIT LONGER TO WARM. AS A RESULT PRECIP
WILL START AS SNOW AND MAY ACCUMULATE A FEW INCHES BEFORE THE
CHANGEOVER TO RAIN SUNDAY EVENING. THIS SCENARIO IS SUPPORTED BY BOTH
NAM AND GFS SOUNDINGS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
LONG RANGE MODELS AND ENSEMBLES IN FAIRLY GOOD AGREEMENT IN THE
EXTENDED...WITH SOME DIFFERENCES IN THE DETAILS BY WEDNESDAY.
SUNDAY NIGHT...CATEGORICAL POPS IN THE EVENING AS FAIRLY ROBUST
THERMAL ADVECTION OCCURS IN ASSOCIATION WITH A WARM FRONT. A 45 TO
50 KT SOUTHERLY LOW LEVEL JET WILL ALLOW FOR NEARLY STEADY OR SLOWLY
RISING TEMPERATURES DURING THE EVENING. BLYR-850MB TEMPERATURES WILL
BE WARM ENOUGH TO SUPPORT RAIN ACROSS MUCH OF THE AREA...EXCEPT ACROSS
THE FAR NORTHWEST INTERIOR WHERE NEARLY ISOTHERMAL THERMAL PROFILES
COULD SUPPORT SOME WET SNOW LINGERING INTO THE EARLY EVENING HOURS.
LITTLE IF ANY ACCUMULATION IS EXPECTED.
MONDAY...A DRY DAY EXPECTED AS THE FORECAST AREA WILL BE UNDER THE
INFLUENCE OF SFC HIGH PRESSURE AND INCREASING SUBSIDENCE. DOWNSLOPING
NW FLOW SHOULD ALLOW FOR HIGHS WELL INTO THE 40S.
MONDAY NIGHT...A WARM FRONT WILL EXTEND EAST INTO THE FORECAST AREA
ALLOWING FOR INCREASING CLOUDS OVERNIGHT. INCREASING WARM AIR
ADVECTION WILL ALLOW FOR SOME OVERRUNNING PRECIPITATION LATE AT
NIGHT. THERMAL PROFILES ACROSS THE INTERIOR ARE COLD ENOUGH TO
SUPPORT A PERIOD OF SNOW AND SLEET...FOLLOWED BY SOME FREEZING RAIN
AS THE MID LEVELS CONTINUE TO WARM. THIS MAY BE ENOUGH TO CAUSE SOME
ISSUES FOR THE TUESDAY MORNING COMMUTE.
TUESDAY...SOME DISCREPANCIES ARISE REGARDING THE PLACEMENT OF A WARM
FRONT ON TUESDAY. THE GFS/NAM GENERALLY AGREE THAT THE FRONT WILL CROSS
MOST OF THE AREA...BUT MAY NOT LIFT NORTH OF THE NEW HAMPSHIRE BORDER
UNTIL THE AFTERNOON. THE BEST ISENTROPIC LIFT WILL REMAIN NORTH OF
THE FRONT DURING THE DAY. ELSEWHERE...THE FORECAST AREA WILL BE
LOCATED WITHIN THE WARM SECTOR. MAY SEE LINGERING PRECIPITATION IN
THE MORNING ACROSS THE NORTHERN ZONES FOLLOWED BY SCATTERED SHOWERS
DURING THE AFTERNOON DUE TO AN APPROACHING COLD FRONT. OTHERWISE
HAVE KEPT CHANCE POPS IN THE FORECAST. FURTHER ADJUSTMENTS MAY BE
NECESSARY DUE TO TIMING ISSUES.
WEDNESDAY THROUGH FRIDAY...MODELS HINTING THAT THE COLDEST AIR MAY BE
DELAYED UNTIL THURSDAY...AS A TRAILING SHORT WAVE CROSSES THE AREA
WEDNESDAY AFTERNOON. MAY NEED TO EVENTUALLY ADD POPS FOR SNOW SHOWERS
WEDNESDAY AND WEDNESDAY EVENING. OTHERWISE ARCTIC AIR OVERSPREADS
THE AREA WEDNESDAY NIGHT AND REMAINS THROUGH THURSDAY. SOME SIGNS
THAT AN ALBERTA CLIPPER MAY APPROACH BY FRIDAY...PROVIDING A
REINFORCING SHOT OF COLDER AIR...BUT FOR NOW GIVEN TIMING AND
PLACEMENT ISSUES HAVE JUST A SLIGHT CHANCE POP.
&&
.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
TODAY...
VFR WITH ONE MORE DAY OF GUSTY WEST WINDS OF 25-35KT...FINALLY
DIMINISHING LATE IN THE DAY FROM WEST TO EAST.
TONIGHT...
VFR ALONG WITH LIGHT WINDS.
SUNDAY...
VFR AND LIGHT WINDS TO START...THEN CIGS LOWER TO MVFR DURING THE
AFTERNOON FROM WEST TO EAST. PRECIP WILL ALSO OVERSPREAD THE REGION
DURING THE AFTERNOON FROM WEST TO EAST WITH CIGS POSSIBLY LOWERING TO
IFR BY DAYS END. WINDS BECOME SOUTHERLY AND YIELDS WARMER TEMPERATURES
WITH PRECIP TAKING THE FORM OF RAIN... EXCEPT A LOW PROB OF AN HOUR
OR TWO OF SNOW AT THE START AT ORH AND MHT.
OUTLOOK /SUNDAY NIGHT THROUGH WEDNESDAY/...
SUNDAY NIGHT...WIDESPREAD MVFR CEILNGS/VSBYS IN -RA WITH -SN WELL
INLAND AS A WARM FRONT APPROACHES THE AREA....BRIEF IFR POSSIBLE
A FEW HOURS SURROUNDING 00Z MONDAY.
MONDAY...VFR BUT PERHAPS MVFR/IFR CEILINGS EARLY ACROSS THE CAPE AND
ISLANDS.
MONDAY NIGHT...COULD SEE A PERIOD OF MVFR CEILINGS AND VSBYS AFT 06Z
WITH LOCAL IFR BY 12Z IN SNOW SHOWERS...MIXED WITH SLEET AND
FREEZING RAIN ACROSS THE NW HALF OF THE REGION...GENERALLY WET SNOW
AND RAIN MIXED NEAR THE COASTAL PLAIN.
TUESDAY...IFR/MVFR CEILINGS. MVFR VSBYS IN MIXED PCPN ACROSS THE
INTERIOR AND SHRA ALONG THE COAST AS A WARM FRONT LIFTS N DURING THE
MORNING. SCT SHRA IN THE AFTERNOON AHEAD OF A COLD FRONT.
TUESDAY NIGHT AND WEDNESDAY...VFR. COULD SEE BRIEF LOCAL MVFR OR IFR
IN WIDLY SCT SNOW SHOWERS WEDNESDAY AFTERNOON WITH A COLD FRONT. NW
WINDS GUSTING TO 30 TO 35 KT...PERHAPS UP TO 40 KT BY WEDNESDAY
EVENING AS THE ARCTIC FRONT CROSSES THE AREA.
&&
.MARINE...
TODAY...
WEST GALES CONTINUE INTO THIS MORNING FOR THE SOUTH COAST AND WILL
LIKELY LINGER ACROSS THE EASTERN MA WATERS ALL DAY.
TONIGHT...
WINDS DIMINISH AS HIGH PRES BUILDS OVER THE AREA.
SUNDAY...
SOUTH WINDS DEVELOP AHEAD OF APPROACH FRONT. SPEEDS MAY INCREASE TO
20-25 KT BY DAYS END. VSBY WILL LIKELY DECREASE WITH RAIN
OVERSPREADING THE WATERS FROM WEST TO EAST DURING THE AFTERNOON.
OUTLOOK /SUNDAY NIGHT THROUGH WEDNESDAY/...
SUNDAY NIGHT...SMALL CRAFT ADVISORIES SHOULD BE NECESSARY. SW WINDS
COULD GUST UP TO 25 KT AHEAD OF A COLD FRONT. SEAS BUILDING TO 4 TO 6
FT. UNDERCUT WNA SEAS BY 20 PCT DUE TO BIAS IN SW FLOW EVENTS.
MONDAY...A SMALL CRAFT ADVISORY FOR NW WINDS GUSTING UP TO 25 KT
ACROSS THE OUTER WATERS THEN SHIFTING TO NE AND DIMINISHING. SEAS
UP TO 6 FT DUE TO SW SWELL.
MONDAY NIGHT...WINDS SHIFTING TO E THEN SE AHEAD OF A DEVELOPING
WARM FRONT. WINDS AND SEAS SHOULD REMAIN BELOW SCA CRITERIA.
TUESDAY...A SMALL CRAFT ADVISORY MAY BE NEEDED. SHIFTING WINDS TO
SOUTHWEST AHEAD OF A COLD FRONT. WINDS COULD GUST TO 20 TO 25 KT AND
SEAS MAY BUILD UP TO 5 FEET LATE.
TUESDAY NIGHT AND WEDNESDAY...MARGINAL GALES POSSIBLE BEHIND A COLD
FRONT. STRONGER GUSTS POSSIBLE BY WEDNESDAY NIGHT AS MUCH COLDER AIR
USHERS ACROSS THE WATERS.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...GALE WARNING UNTIL 7 PM EST THIS EVENING FOR ANZ231-232-250-
251-254-255.
GALE WARNING UNTIL 8 AM EST THIS MORNING FOR ANZ230-233>235-
237-256.
SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR ANZ236.
&&
$$
SYNOPSIS...NOCERA/STRAUSS
NEAR TERM...NOCERA
SHORT TERM...NOCERA
LONG TERM...STRAUSS
AVIATION...NOCERA/STRAUSS
MARINE...NOCERA/STRAUSS
