FXUS61 KBOX 240321
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1021 PM EST WED DEC 23 2009
.SYNOPSIS...
HIGH PRESSURE FROM QUEBEC WILL BUILD SOUTHWARD INTO NEW ENGLAND
PROVIDING MAINLY DRY WEATHER INTO FRIDAY ALONG WITH MODERATING
TEMPERATURES. LOW PRESSURE WILL TRACK UP THE EASTERN SEABOARD THIS
WEEKEND BRINGING A PERIOD OF WINTRY WEATHER INLAND...WITH MAINLY RAIN
AND WIND ALONG THE COAST. THE LOW AND ITS PRECIPITATION SHOULD DEPART
THE REGION SOMETIME LATER SUNDAY...FOLLOWED BY COLDER AND BLUSTERY
WEATHER EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
POLAR VORTEX OVERHEAD PROVIDING CLOUDS AND A COLD CORE ALOFT.
A BAND OF CLOUDS MOVING SOUTH DURING THE EVENING THROUGH OUR
NORTHERN AND WESTERN AREAS...THIS WILL MOVE ACROSS THE REMAINDER OF
SOUTHERN NEW ENGLAND OVERNIGHT AS THE UPPER LOW SLIPS SOUTHEAST.
RADAR SHOWS VERY LIGHT ECHOES IN NORTHERN MASS AS WELL AS A BANDED
STRUCTURE ACROSS THE OUTER CAPE. THIS LAST ISN/T SURPRISING...AS THE
COLD CORE ALOFT IS CREATING A SFC-850 MB TEMP DIFFERENTIAL IN THE LOW
TO MID 20S. WITH THE COLD CORE MOVING OFF OVERNIGHT...THIS WILL
LESSEN WITH THE DELTA-T EXPECTED AROUND 10-11C BY 12Z.
SO FLURRIES ARE POSSIBLE OVER EASTERN AREAS OVERNIGHT...EXCEPT
SCATTERED LIGHT SNOW SHOWERS VCNTY THE OUTER CAPE. CHANCES SHOULD
DIMINISH TOWARD MORNING.
FORECAST MIN TEMPS WERE LOWERED 2-3 DEGREES BASED ON OBSERVED VALUES
AT 10 PM.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
DRY WEATHER THIS PERIOD AS DEEP LAYER RIDGE BUILDS IN FROM THE WEST
AS POLAR VORTEX MOVES OFFSHORE EARLY THU. TEMPS ACTUALLY WARM AT 925
AND 850 DURING THIS TIME. SO EXPECT A NICE REBOUND IN TEMPS TOMORROW
WITH HIGHS IN THE UPPER 30S AND LOW 40S. NORTHERLY FLOW EARLY THU
WILL LIKELY YIELD MOSTLY CLOUDY SKIES ACROSS EASTERN MA. THE
COMBINATION OF CLOUDS AND BRISK NORTH WINDS WILL YIELD COOLER
CONDITIONS ACROSS EASTERN MA. AT LEAST PARTIAL SUNSHINE IS EXPECTED
ACROSS SOUTHWEST NH/WESTERN MA AND INTO CT.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
FORECAST CONCERNS DURING THIS TIME FRAME REVOLVE AROUND POTENTIAL
WINTER WEATHER EVENT FOR THE WEEKEND.
WE ARE STILL LOOKING AT TIMING ISSUES WITH THE ONSET DEPARTURE OF
HEAVIEST PRECIPITATION OVER THE WEEKEND...WITH THE GFS CONTINUING TO
BE A GOOD 6 TO 12 HOURS FASTER THAN THE ECMWF. WILL CONTINUE TO
COMPROMISE ON TIME OF ARRIVAL...TAKING A BIT OF A SLOWER ROUTE AS THE
MEAN MID LEVEL FLOW BECOMES INCREASINGLY MERIDIONAL. WE STILL THINK
THE HEAVIEST PRECIP WITH THE EVENT WILL OCCUR SATURDAY NIGHT INTO
SUNDAY MORNING.
WE THINK FRIDAY /XMAS DAY/ IS A DRY ONE WITH HIGH PRESSURE THROUGHOUT
THE COLUMN DOMINATING. AT THIS TIME WE CAN/T RULE OUT SOME SPRINKLES
ACROSS CT AS LOW LEVEL EASTERLY FLOW TENDS TO MOISTEN DOWN THAT WAY.
AS FAR AS FRIDAY NIGHT GOES...THE LOW LEVELS TEND TO MOISTEN UP A BIT
MORE WITH THE LOW LEVEL EASTERLY FLOW REMAINING IN PLACE.
HOWEVER...THE MID LEVELS LOOK TO REMAIN DRY. DEPENDING ON SURFACE
TEMPERATURES THIS COULD POSSIBLY AID IN THE DEVELOP OF SOME DRIZZLE
OR FREEZING DRIZZLE FOR A GOOD PORTION OF THE AREA...SO WE WILL HAVE
TO CONTINUE TO WATCH THAT ASPECT.
THE COLUMN EVENTUALLY MOISTENS UP DURING THE DAY ON SATURDAY AND THIS
SHOULD ALLOW FOR MORE STEADY MEASURABLE PRECIP TO BEGIN VERY SLOWLY
PROGRESSING ACROSS THE CWA FROM WEST TO EAST. IT/S NOT OUT OF THE
QUESTION THAT AREAS ALONG AND EAST OF I-95 REMAIN DRY THROUGHOUT MUCH
OF THE DAY. AS FAR AS PRECIP TYPE GOES...A MIXTURE WILL BE IN ORDER.
ACROSS THE INTERIOR /MAINLY NORTH OF THE MASS PIKE/...IT LOOKS LIKE A
LIGHT MIXTURE OF SLEET AND SNOW IS THE BEST WAY TO GO FOR NOW. TOWARD
THE COASTAL PLAIN...IT'LL PROBABLY BE WARM ENOUGH FOR RAIN...BUT A
MIXTURE OF SLEET AND RAIN ALONG WITH A FEW SNOWFLAKES WILL BE
POSSIBLE.
THE MAIN FORCING MECHANISMS FOR STRONG ASCENT WILL ARRIVE SATURDAY
NIGHT. THIS WILL LIKELY RESULT IN A PERIOD OF HEAVY PRECIPITATION.
THE FAR INTERIOR SHOULD REMAIN LOCKED IN WITH LOW LEVEL COLD
AIR...AND THIS SHOULD ALLOW FOR ANY SNOW/SLEET TO CHANGE TO A
FREEZING RAIN. THE AMOUNT OF ACCRETION WILL DEPEND ON LOW LEVEL
TEMPS...ANY LOW LEVEL DRY AIR ADVECTION...AS WELL AS PRECIP
INTENSITY. THE POTENTIAL EXISTS FOR A QUARTER TO HALF INCH OF ICE
SOMEWHERE ACROSS THE FAR INTERIOR...BUT WE ARE STILL AWAYS OUT FROM
THE EVENT SO WE HAVE TIME TO HONE IN ON THIS WITH SUBSEQUENT
FORECAST. ON THE COASTAL PLAIN...A RAIN EVENT IS FORECAST. AS OF
RIGHT NOW...AROUND AN INCH TO AN INCH AND A HALF OF PRECIP IS
EXPECTED...BUT LOCALLY HIGHER AMOUNTS OF UP TO 3 INCHES IS POSSIBLE
DUE TO UPSLOPE ENHANCEMENT AND GOOD SELY INFLOW. THIS WOULD BRING
INTO PLAY A CONCERN FOR URBAN AND POOR DRAINAGE FLOODING...BUT THIS
WOULD DEPEND ON HOW MUCH THE CURRENT SNOWPACK WILL ABSORB. IT MAY
ABSORB A LOT...ESPECIALLY SINCE TEMPS AREN/T EXPECTED TO BE VERY WARM
ON THE COASTAL PLAIN FOR A LONG PERIOD OF TIME. COULD SEE IT BRIEFLY
HIT 50F ALONG I-95 CORRIDOR FOR A FEW HOURS.
THE HEAVIEST PRECIP WILL END SUNDAY MORNING AS DRY SLOT RAPIDLY
SWEEPS IN FROM SW TO NE. SUNDAY AFTERNOON COULD ACTUALLY BE HALFWAY
DECENT WITH SUN AND RELATIVELY WARM TEMPS ON THE COASTAL PLAIN BEFORE
COLDER AIR COMES IN AT NIGHT. AS FOR SFC LOW TRACK...THE PRIMARY LOW
SHOULD DIE OFF AS IT MAKES IT TO THE BERKSHIRES WITH A SECONDARY LOW
PROBABLY GOING ROUGHLY FROM NYC-PVD-BVY.
WE/LL PROBABLY HAVE SNOW SHOWERS AROUND ON MONDAY AS UPPER LOW
TRAVERSES THE REGION. COULD PICK UP AN INCH OR TWO IN SPOTS. COULD
END UP BEING A WINDEX-TYPE EVENT MONDAY NIGHT AS ARCTIC BOUNDARY CUTS
ACROSS REGION. WINDY AND MUCH COLDER MONDAY NIGHT AND TUESDAY IN THE
WAKE OF THE FRONT.
FAIR WED BUT CONTINUED COLD.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
TONIGHT...
HIGH CONFIDENCE ON VFR CIGS LOWERING TO MVFR AFTER 06Z. CONFIDENCE IS
LOW ON WESTWARD EXTENT OF MVFR CIGS. THINK HIGHEST PROBABILITY OF
MVFR CIGS LATE TONIGHT ARE FROM MHT/BOS/HYA/FMH AND ACK. ALTHOUGH LOW
PROB OF MVFR CIGS EXTENDING WEST TO PVD-ORH. VFR VSBYS EXPECTED.
NORTHWEST WINDS DIMINISH.
THURSDAY...
HIGH CONFIDENCE ON MVFR CIGS BUT LOW CONFIDENCE ON WESTWARD EXTENT.
FOR NOW EXPECT MVFR CIGS FROM MHT/BOS/HYA/FHM AND ACK...WITH LOWER
CONFIDENCE WESTWARD. NORTHWEST WINDS BECOMING NORTH DURING THE
AFTERNOON. GUSTS 25-30 KT ACROSS HYA AND ACK. WINDS MUCH LESS
ELSEWHERE.
THU NIGHT...
MODERATE TO HIGH CONFIDENCE OF MVFR CIGS CONTINUING AT
MHT/BOS/HYA/FMH AND ACK. VFR ELSEWHERE. NORTH TO NORTHEAST WINDS
BEGIN TO DIMINISH AT HYA AND ACK.
OUTLOOK...FRIDAY THROUGH MONDAY...
FRIDAY...VFR...POSSIBLY BECOMING MVFR LATE.
SATURDAY...VFR OR MVFR TO START...LOWERING TO MVFR OR IFR FROM W-E AS
RAIN OR MIXED PRECIPITATION PUSHES E. LOW CONFIDENCE ON TIMING.
SATURDAY NIGHT AND SUNDAY...IFR CIGS AND MVFR-IFR VSBYS LIKELY WITH
RAIN OR MIXED PRECIPITATION. LOW CONFIDENCE ON TIMING. BECOMING VFR
FROM WEST TO EAST LATE SUN MORNING OR AFTERNOON.
MONDAY...VFR...BUT POSSIBLE MVFR IN SNOW SHOWERS AT TIMES.
&&
.MARINE...
TONIGHT...
NORTHWEST WINDS CONTINUING TO GUST TO 25 KT.
THU...
NORTHWEST WINDS BECOME NORTH WITH GUSTS TO 25 KT.
THU NIGHT...
WINDS DIMINISH AS CANADIAN HIGH PRES BUILDS INTO NEW ENGLAND.
OUTLOOK...FRIDAY THROUGH MONDAY...
FRIDAY...LIGHT NORTHEAST TO EAST WINDS. SEAS STILL AOA SCA
LEVELS...MAINLY ON OUTER WATERS.
FRIDAY NIGHT...SMALL CRAFT WINDS AND SEAS.
SATURDAY-SUNDAY...EAST-SOUTHEAST WINDS PROBABLY INCREASE TO GALE
SATURDAY NIGHT AND CONTINUE INTO SUNDAY. SEAS BUILD.
MONDAY...SCA WINDS AND SEAS.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST THURSDAY FOR ANZ231>235-
237-250-251-254>256.
&&
$$
SYNOPSIS...NOCERA/EKSTER
NEAR TERM...WTB
SHORT TERM...NOCERA
LONG TERM...EKSTER
AVIATION...NOCERA/EKSTER
MARINE...NOCERA/EKSTER
