FXUS61 KBOX 090358
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1058 PM EST TUE DEC 8 2009
.SYNOPSIS...
A STRONG STORM WILL AFFECT SOUTHERN NEW ENGLAND WEDNESDAY WITH
MIXED PRECIPITATION AND A PERIOD OF STRONG WINDS ON THE COAST.
BLUSTERY AND CHILLY WEATHER WILL FOLLOW THURSDAY INTO EARLY NEXT
WEEK. A PERIOD OF RAIN AND OR SNOW SHOWERS ARE POSSIBLE ON SUNDAY
IN ASSOCIATION WITH A WAVE OF LOW PRESSURE.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
REVIEWED 00Z NAM AND BUFKIT OUTPUT WHICH SUPPORTS CURRENT FORECAST
AND HAZARDOUS WEATHER IMPACTS. 00Z NAM CONTINUES TO ADVERTISE SECONDARY
SURFACE LOW DEVELOPMENT MOVING UP THE COAST AND CROSSING IN VICINITY
OF CAPE COD CANAL WED AFTN. LATEST SURFACE ANALYSIS ALREADY SHOWING
SIGNIFICANT PRES FALL CENTER ALONG VA/NC COAST WITH 5MB PRES FALL
PAST 3 HRS.
THIS SECONDARY CIRCULATION WILL HELP TO BEND SURFACE WIND TO EAST-
NORTHEAST INLAND AND INITIALLY MAINTAIN LOW LEVEL COLD AIR. NAM IS
COLDER THAN PREVIOUS RUNS SO WILL HAVE TO WATCH THIS TREND AND SEE IF
GFS HAS COLD SIGNAL AS WELL. STRONG MID LEVEL SW JET EJECTING
NORTHWARD FROM MID ATLC WILL INTENSIFY OVERNIGHT WITH 80 KT CORE FROM
NE PA SOUTHWEST TO SOUTH OF LONG ISLAND. THIS JET CONTINUES TO
INTENSIFY TO 90 KT BY 18Z OVER CAPE COD. THIS WILL RESULT IN STRONG
MID LEVEL LIFT DURING THE MORNING HOURS WHICH COULD LEAD TO A BURST OF
HEAVY SNOW DURING THE MORNING COMMUTE AS FAR SOUTH AS I95 CORRIDOR.
THEREFORE WE MAY EXTEND WINTER WEATHER ADVISORY SOUTHEAST INTO THE
BOSTON- PROVIDENCE CORRIDOR. THE IMMEDIATE COAST SHOULD CHANGE OVER
FAIRLY QUICKLY GIVEN STRONG EASTERLY ONSHORE FLOW.
AS FOR THE HIGH WIND WATCH...00Z NAM HAS VERY STRONG PRES FALL CENTER OF
13MB/3HR CENTERED OVER CAPE COD 18Z-21Z! THIS COMBINED WITH STRONG
LOW LEVEL EASTERLY JET OF 65 KT WILL LIKELY RESULT IN A PERIOD OF
STRONG TO DAMAGING WINDS ACROSS NANTUCKET AND CAPE COD. NAM BUFKIT
SOUNDINGS SUPPORT GUSTS NEAR 50 KT ACROSS THIS AREA. THUS...LEANING
TOWARD A HIGH WIND WARNING. ALTHOUGH WILL REVIEW 00Z GFS/03Z SREF AND
OTHER MODEL DATA BEFORE DECIDING.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
*** MULTI HAZARD WEDNESDAY AND EXTRA TIME-CAUTION IS URGED REACHING
DESTINATIONS***
THE ADVISORY AND ASSOCIATED SNOW POSTED AT 4PM WILL PROBABLY NEED
CHANGES.
UNCERTAINTY EXISTS ALONG THE EDGES...ESPECIALLY ORH TO WOONSOCKET
BOSTON AND LWM WHERE AMOUNTS STILL COULD BE 1-2 INCHES HIGHER THAN
CURRENTLY FCST.
BL TEMPERATURES ON THE NAM ARE IN A SLIGHT WARMING TREND THE PAST
2 CYCLES. FGEN/SNOWGROWTH AND THE ASSOCIATED FRONT END THUMP /COINED
BY OTHERS IN OUR OFFICE/ CONTINUE BUT WITH SOME CONCERNS E OF THE
CT RVR VALLEY WHERE NOT QUITE AS IDEAL SNOWGROWTH AND WARMER BL
TEMPS SUGGEST THAT SNOWFALL RATES MAY BE CLOSER TO HALF AN INCH AN
HR AND PACKED DUE TO BL WARMTH.
PREFERRED CONSERVATIVE APPROACH...ESP SINCE IT WAS SLIGHTLY WARMER
TODAY THAN LAST FRIDAY AND THE SAT EVENT STRUGGLED ON PAVEMENT AMTS.
FOR NOW...2 HRS OF 1/HR APPEARS PROBABLE ALONG OR W OF I84 TO FIT
MHT.
PRIMARY SFC LOW TO OUR WEST IS A BAD SIGN BUT INTENSIFYING WFRONTAL
WAVE WILL TUCK SFC COLD AIR IN ALL DAY AND UNDERCUT THE BLENDED 12Z
NCEP MOS USING THE 12Z 2M NAM TEMPS.
WINDS WERE RUN OFF THE 12Z NAM MXG HTS. WE CKD MOS GUIDE WHICH WAS
EVEN HIGHER THAN OUR FCST GUSTS.
HEAVY RAIN WILL PROBABLY REQUIRE URBAN SMALL STREAM FLOOD ADVISORY
MIDDAY AND AFTN.
EVEN A SMALL CHC OF A GUSTY TSTM MID OR LATE AFTN SE COAST. 12Z
ECMWF ESP SUPPORTIVE.
COASTAL FLOODING IS RELATED TO THE GFS LOW BIAS ON ITS FCSTS WITH
ONSHORE FLOW...INCLUDING TUESDAY... PROMPTED THE NEED FOR CFA.
12Z SWAN GFS FINALLY UPPED THE WH. WE THINK THESE ARE PRETTY GOOD AND
BETTER THAN 12Z GFS WNA4.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
WEDNESDAY NIGHT THROUGH FRIDAY NIGHT...
SHORT RANGE MODELS THROUGH THURSDAY SHOWING FAIRLY GOOD AGREEMENT AS
LOW PRES PUSHES INTO THE MARITIMES...WITH MUCH COLDER TEMPERATURES
POURING INTO THE REGION LEADING INTO THE WEEKEND AS W WINDS CRANK UP.
EXPECT MAINLY DRY CONDITIONS ACROSS THE REGION...BUT THERE WILL
DEFINITELY BE A MORE WINTRY FEEL. WITH THE STRONG LOW LAYING ACROSS
EASTERN AND CENTRAL CANADA AND HIGH PRES ACROSS THE MID ATLC...
RATHER STRONG W-NW WINDS WILL PUMP COLD AIR ACROSS THE REGION. BOTH
925 AND 850 HPA HAVE STRONG WIND MAXIMAS MOVING ACROSS THE REGION...
KICKING IN WEDNESDAY NIGHT AND RUNNING THROUGH AT LEAST FRIDAY. H85
TEMPS CONTINUALLY FALL AS WELL...DROPPING TO -16C TO -18C BY 12Z
FRIDAY.
WITH THE STRONG W WINDS THROUGH THE LOWER LEVELS AND EXCELLENT
TRAJECTORY ACROSS NY STATE...EXPECT CONVEYOR BELT OF SNOW SHOWERS
OFF LAKE ONTARIO TO CROSS NY STATE INTO W MA/SW NH WEDNESDAY NIGHT
AND THURSDAY. HAVE MENTIONED CHANCE POPS INTO THE E SLOPES OF THE
BERKSHIRES INTO SW NH...POSSIBLY REACHING THE HARTFORD/SPRINGFIELD
AREAS INTO S CENTRAL NH THURSDAY AFTERNOON. COULD SEE ANOTHER BATCH
FRIDAY NIGHT...THOUGH NOT QUITE AS MUCH COVERAGE...POSSIBLY REACHING
INTO WESTERN FRANKLIN AND CHESHIRE COUNTIES.
ON THURSDAY...TEMPS WILL ONLY RISE A FEW DEGS ABOVE WEDNESDAY NIGHTS
LOWS AS THE STRONG COLD AIR ADVECTION WORKS IN...WITH HIGHS TOPPING
OFF CLOSE TO OR AS MUCH AS 5 DEGREES BELOW SEASONAL NORMS. OVERNIGHT
LOWS THURSDAY NIGHT WILL FALL TO THE TEENS AND 20S. HOWEVER...BY
FRIDAY...DAYTIME HIGHS WILL BE MUCH COLDER...STRUGGLING TO REACH THE
MID 30S ACROSS E MA EVEN ON THE CAPE AND ISLANDS...BUT REMAINING
BELOW FREEZING ACROSS THE HIGHER TERRAIN OF CENTRAL-W MA/S NH.
HOWEVER...WITH THE STRONG W WINDS...IT WILL FEEL MORE LIKE TEMPS IN
THE TEENS TO LOWER 20S.
SATURDAY AND SATURDAY NIGHT...
A RIDGE OF HIGH PRESSURE WILL BUILD IN FROM THE WEST AND PROVIDE DRY
WEATHER THROUGH SATURDAY NIGHT. TEMPERATURES WILL BE MILDER THAN ON
FRIDAY...BUT IT STILL WILL BE CHILLY. EXPECT HIGHS ON SATURDAY TO
RANGE FROM THE MID TO UPPER 30S ACROSS THE INTERIOR...AND FROM
AROUND 40 TO THE LOWER 40S ON THE COASTAL PLAIN.
SUNDAY...
HIGH PRESSURE MOVING OFF THE COAST WILL RESULT IN WARM AIR ADVECTION
AND SOME MID LEVEL LIFT. THIS MAY RESULT IN A PERIOD OF SNOW
SHOWERS ACROSS THE INTERIOR...BUT AMOUNTS AT THIS POINT LOOK LIGHT.
BOUNDARY LAYER MAY BECOME WARM ENOUGH ALONG THE COASTAL PLAIN FOR
RAIN OR SNOW SHOWERS. THERE ALSO IS A WAVE OF LOW PRESSURE THAT IS
EXPECTED TO SCOOT OFF THE MID ATLANTIC COAST. AT THIS POINT...THE
UPPER LEVEL FLOW DOES NOT LOOK AMPLIFIED TO BRING THE STORM CLOSE
ENOUGH TO THE COAST FOR A SIGNIFICANT STORM IN SOUTHERN NEW
ENGLAND. IN FACT...THE MODELS GENERATE MOST OF THE LIGHT QPF IN THE
WARM AIR ADVECTION PATTERN. HOWEVER...THIS IS A DAY 5 FORECAST AND
WILL CERTAINLY HAVE TO KEEP OUR OPTIONS OPENED FOR A TRACK CLOSER TO
THE COAST THAN CURRENTLY EXPECTED. FOR NOW JUST RAN WITH SOME
CHANCE POPS FOR A PERIOD OF RAIN OR SNOW SHOWERS ON SUNDAY.
SUNDAY NIGHT THROUGH TUESDAY...
A COLD FRONT LOOKS TO MOVE THROUGH THE REGION SOMETIME SUNDAY
NIGHT OR MONDAY...BUT THE MODELS DIFFER A BIT ON THE TIMING. EITHER
WAY...CONFIDENCE IS MEDIUM TO HIGH THAT A SHOT OF COLD AIR WILL WORK
IN BEHIND THE FRONT. A FEW PASSING RAIN/SNOW SHOWERS ARE CERTAINLY
POSSIBLE WITH THE FRONT SUNDAY NIGHT OR MONDAY...BUT JUST WENT WITH
A 20 POP AS MOISTURE WILL BE LACKING. OTHERWISE...EXPECT MAINLY DRY
AND COLD WEATHER FOR MONDAY NIGHT AND TUESDAY.
ANOTHER LOW PRESSURE SYSTEM DEVELOPING OFF THE MID ATLANTIC COAST
MAY THREATEN THE REGION WITH SNOW OR MIXED PRECIPITATION BEGINNING
TUESDAY NIGHT. HOWEVER...CONFIDENCE AND TIMING THIS FAR OUT IS LOW.
&&
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
TONIGHT...STARTING OFF WITH VFR CIGS...THEN LOWERING TO MVFR-IFR
CIGS/VSBYS AFTER MIDNIGHT ACROSS CT VALLEY...PUSHING TO CENTRAL MA/RI
BY 10Z.
WEDNESDAY...IFR-LIFR CIGS/VSBYS COMMON ACROSS THE REGION IN MIXED
RA/SN/PL EVENTUALLY CHANGING OVER TO RA FROM THE COAST TO INLAND
AREAS AS E WINDS INCREASE. COULD SEE WIND GUSTS CLOSE TO 50 KTS AT
COASTAL LOCATIONS AROUND MIDDAY OR EARLY AFTERNOON. WINDS WILL SHIFT
TO S-SW LATE IN THE DAY.
OUTLOOK /WEDNESDAY NIGHT THROUGH SUNDAY/...
WEDNESDAY NIGHT...MVFR CIGS/VSBYS IN RAIN/SNOW SHOWERS TO START...
THEN QUICKLY IMPROVE TO VFR. MVFR CIGS/VSBYS MAY LINGER ACROSS E
SLOPES OF THE BERKSHIRES IN -SHSN.
THURSDAY...VFR CONDITIONS. STRONG W WINDS WILL CARRY LAKE EFFECT
-SHSN ACROSS SW NH INTO W MA. EXPECT AREAS MVFR CIGS/VSBYS IN THESE
AREAS. W WINDS GUSTING TO 30-35 KT DURING THE DAY...DIMINISHING TO
AROUND 25 KT AT NIGHT.
FRIDAY...VFR. LOCAL MVFR CIGS/VSBYS IN -SHSN INVOF NORTHERN
BERKSHIRES INTO SW NH. W WINDS GUSTING TO AROUND 30 KT ALONG THE
COAST AND ACROSS HIGHER TERRAIN N CENTRAL AND NW MA/S NH.
SATURDAY AND SATURDAY NIGHT...MAINLY VFR.
SUNDAY...A PERIOD OF MVFR-IFR CONDITIONS ARE POSSIBLE IN RAIN AND OR
SNOW SHOWERS.
&&
.MARINE...
MWW HAS THE GALE AND STORM DETAILS BEHIND THE HEADLINES. PRD OF
STORM FORCE E GUSTS MIDDAY WED.
SFC WAVE CUTS THRU COASTAL SE MASS LATE AFTN. SEEMS LIKE IT WILL PASS
JUST E OF BOS BUT WEST OF 44013.
OUTLOOK /WEDNESDAY NIGHT THROUGH SUNDAY/...
WEDNESDAY NIGHT...W WINDS INCREASE TO GALE FORCE WITH GUSTS
APPROACHING 40 KT. USED A BLEND OF THE PREVIOUS FORECAST AND BOTH
THE WNA WAVEWATCH MODELS /INCLUDING THE HURRICANE VERSION/. FEEL
SEAS WILL BE HIGHER THAN DEPICTED BY WNA ALONE. SEAS COULD APPROACH
15 KT ON THE SOUTHERN OUTER WATERS.
THURSDAY...GALE FORCE WINDS CONTINUE WITH GUSTS UP TO 40-45 KT. SEAS
UP TO 10-15 FT.
FRIDAY...W WINDS CONTINUE AT GALE FORCE. SEAS SLOWLY SUBSIDE...BUT
STILL UP TO 10-12 FT.
SATURDAY...WESTERLY FLOW SHOULD YIELD SCA WIND GUSTS ACROSS MOST OF
OUR WATERS. IN ADDITION...SEAS 5 FEET OR HIGHER ARE EXPECTED TO
CONTINUE ACROSS THE OUTER-WATERS.
SATURDAY NIGHT AND SUNDAY...WINDS AND SEAS SHOULD DROP BELOW SCA
CONDITIONS FOR A TIME AS A RIDGE OF HIGH PRESSURE BUILDS OVER THE
WATERS. WINDS AND SEAS MAY PICKUP ONCE AGAIN LATER SUNDAY OR SUNDAY
NIGHT BEHIND A LOW PRESSURE SYSTEM IN THE COLD AIR ADVECTION PATTERN.
&&
.HYDROLOGY...
PRECIPITATION TOTALS /MOSTLY RAIN/ OF 1 TO 1.5 INCHES ARE POSSIBLE
NEAR COAST BY WED EVENING. WHILE THIS MAY RESULT IN URBAN AND POOR
DRAINAGE FLOODING...ESPECIALLY NEAR S COAST...MAINSTEM RIVERS ARE
EXPECTED TO REMAIN WITHIN THEIR BANKS.
&&
.TIDES/COASTAL FLOODING...
SE GRADIENT RAISES RISK OF MINOR COASTAL FLOODING ALONG MAINLY SE
FACING COASTLINES DURING THE WED AFTERNOON HIGH TIDE. ETSS OUTPUT
GIVES ABOUT 1.5 FT ALONG THE MA E FACING COAST AND 2 TO 3 FT ALONG
THE S FACING COASTS OF RI AND BUZZARDS BAY. RECOGNIZING THAT THE
SURGE FROM THE ETSS TENDS TO BE CONSERVATIVE...WE HAVE ADDED A FEW
TENTHS TO HALF A FOOT TO THE MODEL VALUES. THE STRONGEST GRADIENT
LOOKS TO COINCIDE CLOSELY WITH THE TIME OF HIGH TIDE ALONG BOTH THE
S COAST AND E COAST OF MA...EVEN THOUGH THE HIGH TIDE TIMES
THEMSELVES ARE DIFFERENT. WAVES OF 10 TO 15 FT NOT TOO FAR OFFSHORE
WILL YIELD A SPLASH OVER RISK ALONG THE EXPOSED COASTLINES. UPPER
NARRAGANSETT BAY COULD GET CLOSE TO MODERATE...SO A CHANCE THAT THE
ADVISORY MAY HAVE TO BE UPGRADED THERE. ONE SPECIAL CASE IS
PROVINCETOWN HARBOR. WOULD NOT EXPECT A SE WIND TO GENERATE MUCH
SURGE THERE BUT ONCE THE WIND SHIFTS TO SSW...THEN COULD SEE A
SUDDEN SURGE OF PERHAPS 1.5 FEET OR SO AND AN ONSHORE WIND FOR
SPLASH OVER ALONG THE HARBOR FRONT.
&&
.EQUIPMENT...
GLOUCESTER NWR TRANSMITTER IS NOW ON THE AIR. MAINTENANCE AT THE
JOHNSTON/PROVIDENCE NWR TRANSMITTER HAS ALSO BEEN COMPLETED. THIS
STATION SHOULD BE BACK ON FULL POWER.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY FROM 4 AM TO 9 AM EST WEDNESDAY FOR
CTZ002>004.
MA...WIND ADVISORY FROM 8 AM TO 3 PM EST WEDNESDAY FOR MAZ007-015-
016-018>021.
COASTAL FLOOD ADVISORY FROM 3 PM TO 7 PM EST WEDNESDAY FOR
MAZ007-014>016-019-022.
WINTER WEATHER ADVISORY FROM 4 AM TO 9 AM EST WEDNESDAY FOR
MAZ006-007-013-014.
WINTER WEATHER ADVISORY FROM 4 AM TO 1 PM EST WEDNESDAY FOR
MAZ002>005-008>012-026.
COASTAL FLOOD ADVISORY FROM NOON TO 3 PM EST WEDNESDAY FOR
MAZ020-021.
HIGH WIND WATCH FROM 7 AM EST WEDNESDAY THROUGH WEDNESDAY
AFTERNOON FOR MAZ022>024.
NH...WINTER STORM WARNING FROM 4 AM TO 5 PM EST WEDNESDAY FOR
NHZ011-015.
WINTER WEATHER ADVISORY FROM 4 AM TO 1 PM EST WEDNESDAY FOR
NHZ012.
RI...WIND ADVISORY FROM 8 AM TO 3 PM EST WEDNESDAY FOR RIZ006>008.
WINTER WEATHER ADVISORY FROM 4 AM TO 9 AM EST WEDNESDAY FOR
RIZ001.
COASTAL FLOOD ADVISORY FROM NOON TO 3 PM EST WEDNESDAY FOR
RIZ002-004>007.
MARINE...STORM WARNING FROM 9 AM TO 5 PM EST WEDNESDAY FOR ANZ231-232-
250-254-255.
GALE WARNING FROM 7 AM TO 5 PM EST WEDNESDAY FOR ANZ230-
233>237-251-256-270>273.
&&
$$
SYNOPSIS...DRAG/FRANK
NEAR TERM...NOCERA
SHORT TERM...DRAG
LONG TERM...FRANK/EVT
AVIATION...DRAG/FRANK/EVT
MARINE...DRAG/FRANK/EVT
HYDROLOGY...
TIDES/COASTAL FLOODING...
EQUIPMENT...
