FXUS61 KBOX 270943
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
443 AM EST FRI NOV 27 2009
.SYNOPSIS...
A COASTAL STORM DEVELOPING SOUTH OF NANTUCKET WILL RAPIDLY INTENSIFY
AS IT TRACKS NORTHWARD INTO THE GULF OF MAINE THIS AFTERNOON AND
THEN INTO THE MARITIMES TONIGHT AND SATURDAY. HIGH PRESSURE WILL
BRING DIMINISHING WINDS AND MILDER CONDITIONS SUNDAY. A COLD FRONT
MOVES ACROSS THE AREA BRINGING SHOWERS MONDAY AND MONDAY
NIGHT...FOLLOWED BY COOLER AND DRIER WEATHER TUESDAY AND WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
COASTAL STORM SOUTH OF ACK WILL UNDERGO RAPID CYCLOGENESIS THROUGH
TODAY IN RESPONSE TO FAVORABLE JET DYNAMICS AND 200-240M HEIGHT FALL
CENTER MOVING OFF THE COAST. MID LEVEL TROF BECOMES NEG TILTED
WHICH FORCES STORM TO HUG NEW ENG COAST AND MOVE NWD INTO GULF OF
MAINE THIS AFTERNOON.
RAIN IS OVERSPREADING SNE EARLY THIS MORNING AND WILL CONTINUE TO
MOVE NWD THROUGH 12Z. DRY SLOT MOVES ACROSS THE COASTAL PLAIN AFT
12Z WHICH WILL ALLOW THE RAIN TO TAPER OFF IN THIS REGION THIS
MORNING...BUT CANT RULE OUT A FEW TSTMS ALONG AND E OF I95 CORRIDOR
FROM BOS-PVD ON THE EDGE OF THE DRY SLOT. NAM/GFS BOTH SHOW STRONG
ELEVATED THUNDER SIGNAL WITH TT IN LOW TO MID 50S AND UNSTABLE SWI.
STEADIER RAIN WILL SHIFT TO THE INTERIOR AFT 12Z AND CONTINUING INTO
THE AFTERNOON AS DEFORMATION BAND SETS UP ALONG AND WEST OF THE
DEEPENING MID LEVEL CENTER. WE THINK THE NAM IS CAPTURING THIS
COMMA HEAD PRECIP THIS AFTERNOON BETTER THAN THE GFS. AS STORM
INTENSIFIES AND UPPER LOW MOVES OVERHEAD...DYNAMIC COOLING WILL COOL
THE COLUMN AND MAY SEE A MIX/CHANGE TO SNOW OVER THE HIGHER
ELVATIONS OF THE BERKS...MONADNOCKS AND NORTHERN ORH HILLS THIS
AFTERNOON. NAM IS MOST AGGRESSIVE WITH THIS COOLING AND WOULD
SUGGEST AT LEAST A FEW INCHES ABOVE 1000 FT...BUT GFS IS SLOWER WITH
THE COOLING WITH MINIMAL ACCUM. WE HAVE INDICATED A MIX OF
RAIN/SNOW OVER THE HIGHER TERRAIN BUT NO ACCUM YET. HOWEVER...DONT
THINK WE CAN COMPLETELY DISCOUNT THE NAM SOLUTION AS SREF IS SHOWING
INCREASING POPS FOR FOR 1" AND 4" OVER SW NH. DAY SHIFT WILL NEED
TO EVALUATE THIS FURTHER.
AS THE STORM MOVES TO THE NORTH...WINDS WILL SHIFT TO THE WEST AND
INCREASE THIS AFTERNOON...FIRST ALONG THE SOUTH COAST THEN SPREADING
NORTH. HOWEVER...THE STRONGEST WINDS WILL OCCUR TONIGHT.
MAX TEMPS WILL OCCUR THIS MORNING WITH COOLING TEMPS THIS
AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
VERTICALLY STACKED LOW WILL SLOWLY DRIFT EWD FROM GULF OF MAINE
TONGIHT. AREA OF DEEPER MOISTURE AND OMEGA ROTATING AROUND THE
UPPER LOW WILL SWING THOUGH SNE TONIGHT AND LIKELY BRING ANOTHER
PERIOD OF SHOWERS...WITH MIXED RAIN/SNOW HIGHER TERRAIN. MINOR
ACCUM POSSIBLE IN THE NW HIGHER TERRAIN. SFC TEMPS MAY HOLD STEADY
OR EVEN SLOWLY RISE TONIGHT AS MID LEVEL COLD POOL MOVES EWD.
AFTER COORD WITH SURROUNDING OFFICES...WE EXPANDED THE WIND ADVISORY
FOR ALL SNE FOR TONIGHT AS LOW LEVEL WIND FIELD INCREASES WITH 40-45
KT DOWN TO 925 MB. GFS IS MORE BULLISH THAN THE NAM ON THE STRONG
WIND POTENTIAL. STRONGEST WINDS WILL LIKELY BE NEAR THE COAST WHERE
BEST MIXING...WITH SECONDARY MAX POSSIBLE OVER THE HIGHER TERRAIN.
MODERATE TO HIGH CONFIDENCE FOR WIND ADVSY NEAR THE COAST WITH LOWER
CONFIDENCE IN THE INTERIOR.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
VERTICALLY STACKED LOW PRESSURE OVER THE MARITIMES CONTINUES MOVING
NORTH SATURDAY. THE LOW WILL BE LED BY PRESSURE FALLS OF 2 MB PER
HOUR AND TRAILED BY PRESSURE RISES OF 1 MB PER HOUR. THAT WILL MEAN
CONTINUED STRONG WINDS FOR AT LEAST THE START OF SATURDAY...WITH
WINDS THEN DIMINISHING LATE IN THE DAY AS THE STRONGEST RISES MOVE
INTO THE MARTIMES. THERE WILL ALSO BE SUFFICIENT COLD ADVECTION TO
PROMOTE MIXING OF STRONGER GUSTS FROM 3000-4000 FEET. WINDS AT THAT
LEVEL REACH 40 TO 45 KNOTS WITH WINDS 50 TO 60 KNOTS JUST ABOVE THE
EXPECTED MIXING HEIGHT. THE WIND ADVISORY WILL CONTINUE THROUGH AT
LEAST MIDDAY SATURDAY...BEST BETS FOR WINDS WOULD BE OVER THE CAPE
AND ISLANDS AND OVER THE HIGHER ELEVATIONS OF THE INTERIOR.
WINDS DIMINISH SATURDAY NIGHT AND SUNDAY AS HIGH PRESSURE BUILDS OVER
THE REGION.
THE NEXT WEATHER MAKER WILL BE A COLD FRONT MOVING ACROSS FROM THE
GREAT LAKES. CLOUDS LEADING THE FRONT MAY REACH US LATE SUNDAY...BUT
MOST INCREASE IN CLOUDS WILL OCCUR SUNDAY NIGHT. THE VARIOUS MODELS
HAVE DIFFERENT TIMING FOR THIS FRONT...WITH THE NAM AND GFS FASTER
AND THE ECMWF SLOWER. WITH THE DIGGING OF AN UPPER TROF OVER THE
LAKES AND RESULTING SOUTHWEST FLOW OVER US...WE PREFER THE SLOWER
ECMWF SCENARIO. THIS WOULD BRING THE FRONT THROUGH LATE MONDAY OR
MONDAY NIGHT. EXPECT LIGHT SHOWERS...THE PRECIP TYPE SHOULD MOSTLY BE
RAIN BUT FORECAST THERMAL PROFILES SHOW A POTENTIAL FOR A CHANGE TO
SNOW MONDAY NIGHT AFTER THE COLD FRONT MOVES THROUGH ESPECIALLY IN
THE NORTH AND WEST. THIS COULD BRING AN INCH OR TWO OF SNOW TO THE
BERKSHIRE EAST SLOPES/MONADNOCKS/NORTHERN WORCESTER HILLS.
TUESDAY AND WEDNESDAY LOOK DRY AND COOL AS HIGH PRESSURE MOVES
THROUGH. THE GFS SHOWS ANOTHER COASTAL LOW MOVING PAST ON WEDNESDAY
NIGHT...THE ECMWF BRINGS IT THROUGH ON THURSDAY. WILL FAVOR THE ECMWF
SOLUTION AND FORECAST CHANCE POPS FOR THURSDAY.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
WIDESPREAD IFR/MVFR CONDITIONS TODAY AS RAIN OVERSPREADS THE
REGION. MAY SEE A MIX WITH SNOW OVER THE HIGHER ELELVATIONS THIS
AFTERNOON AND HAVE INDICATED THIS IN THE ORH TAF. SOME IMPROVEMENT
POSSIBLE IN THE LOWER CT VALLEY AND COASTAL PLAIN THIS AFTERNOON AS
WESTERLY WINDS INCREASE. WEST WIND GUSTS INCREASE TO 25-30 KTS
LATER TODAY.
TONIGHT...GUSTY WEST WINDS TO 35-40 KT POSSIBLE...ESPECIALLY HYA-ACK
AND ORH. CONDITIONS SHOULD IMPROVE TO VFR IN THE COASTAL
PLAIN...BUT MVFR PERSISTING IN THE DISTANT INTERIOR...ESPECIALLY
ORH-MHT.
OUTLOOK /SATURDAY THROUGH TUESDAY/...
SATURDAY...CONDITIONS IMPROVING TO VFR IN THE MORNING. STRONG
NORTHWEST WINDS THROUGH AT LEAST MIDDAY WITH SUSTAINED WINDS 20 TO 30
KNOTS AND GUSTS 40 TO 45 KNOTS. WINDS WILL DIMINISH LATE SATURDAY.
SUNDAY...VFR.
MONDAY...CIGS LOWERING TO MVFR IN ADVANCE OF A COLD FRONT...AREAS OF
MVFR VSBYS IN SHOWERS.
MONDAY NIGHT...MVFR CIGS WITH SCATTERED MVFR VSBYS IN RAIN
SHOWERS...POSSIBLE SNOW SHOWERS FAR INTERIOR.
TUESDAY...VFR.
&&
.MARINE...
NE WINDS SHIFT TO THE WEST TODAY AS COASTAL STORM TRACKS NORTH OF
THE WATERS. STRONGEST WESTERLY WINDS WILL OCCUR LATER TODAY AND
ESPECIALLY TONIGHT AS LOW LEVEL WINDS INCREASE FROM SOUTH TO NORTH.
GALE WARNING EXPANDED TO ALL WATERS STARTING OVER THE SOUTH COASTAL
WATERS LATER TODAY THAN EASTERN WATERS TONIGHT. GUSTS TO 45 KT
LIKELY OVER THE COUTH COASTAL WATERS AND 35-40 KT ELSEWHERE. LOW
PROB FOR STORM FORCE WINDS TONIGHT SOUTHERN WATERS.
OUTLOOK /SATURDAY THROUGH TUESDAY/...
SATURDAY...NORTHWEST GALES CONTINUE...WITH WINDS DIMINISHING SATURDAY
NIGHT. SEAS BUILDING TO 8 TO 15 FEET ON THE OUTER WATERS...SUBSIDING
AFTER MIDNIGHT.
SUNDAY...WINDS AT SMALL CRAFT ADVISORY LEVEL IN THE MORNING BUT
DROPPING BELOW 25 KNOTS AFTERNOON. SEAS DIMINISH BELOW 5 FEET ON THE
INNER WATERS...BUT REMAIN AT OR ABOVE 5 FEET ON THE OUTER WATERS.
MONDAY-TUESDAY...INCREASING SEAS AND SOUTHWEST WINDS AHEAD OF A COLD
FRONT. WINDS AND SEAS MAY REACH SMALL CRAFT ADVISORY LEVELS.
CONDITIONS CONTINUE IN THE NORTHWEST FLOW BEHIND THE FRONT TUESDAY.
&&
.CLIMATE...
IT IS INTERESTING TO NOTE THAT BOSTON/S LOGAN AIRPORT HAS NOT FALLEN
TO THE FREEZING MARK SO FAR THIS SEASON. THE LATEST IN THE SEASON
THAT BOSTON HAS GONE WITHOUT HITTING 32F WAS DEC 2ND 1975. IT IS
POSSIBLE WE BREAK THAT RECORD...BUT IT WILL BE CLOSE SUNDAY NIGHT...
AND NOT COMPLETELY OUT OF THE QUESTION SATURDAY NIGHT...BUT A LOWER
PROBABILITY THEN.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...WIND ADVISORY FROM 6 PM THIS EVENING TO NOON EST SATURDAY FOR
CTZ002>004.
MA...WIND ADVISORY FROM 6 PM THIS EVENING TO NOON EST SATURDAY FOR
MAZ002>024-026.
NH...WIND ADVISORY FROM 6 PM THIS EVENING TO NOON EST SATURDAY FOR
NHZ011-012-015.
RI...WIND ADVISORY FROM 6 PM THIS EVENING TO NOON EST SATURDAY FOR
RIZ001>008.
MARINE...GALE WARNING FROM 3 PM THIS AFTERNOON TO 3 PM EST SATURDAY FOR
ANZ232>235-237-255-256.
GALE WARNING FROM 6 PM THIS EVENING TO 3 PM EST SATURDAY FOR
ANZ230-231-236-250-251-254.
&&
$$
SYNOPSIS...WTB/KJC
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...WTB
AVIATION...WTB/KJC
MARINE...WTB/KJC
CLIMATE...
