291
FXUS61 KBOX 180658
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
158 AM EST THU DEC 18 2025
WHAT HAS CHANGED
HIGH WIND WATCH FOR CAPE AND ISLANDS UPGRADED TO A HIGH WIND
WARNING. WIND ADVISORIES REMAIN IN EFFECT FOR REST OF SOUTHERN NEW
ENGLAND. STORM WARNINGS ISSUED FOR WATERS ADJACENT TO CAPE COD AND
SOUTH OF THE ISLANDS.
KEY MESSAGES
- LOCALLY HEAVY RAINFALL AND STRONG TO DAMAGING WIND GUSTS LATE
TONIGHT INTO FRIDAY
- MUCH COLDER WITH GUSTY WEST WIND GUSTS FRIDAY NIGHT
- COASTAL FLOOD RISK ALONG SOUTH COAST FRIDAY MORNING HAS ENDED
- NEXT SYSTEM MOVES THROUGH LATE SATURDAY INTO SUNDAY BRINGING
LIGHT RAIN SATURDAY AND GUSTY WINDS SUNDAY INTO MONDAY.
DISCUSSION
KEY MESSAGE 1...LOCALLY HEAVY RAINFALL AND STRONG TO DAMAGING
WINDS.
A WIDESPREAD RAIN EVENT IS EXPECTED LATE THU NIGHT INTO FRI AS A
ROBUST UPPER TROUGH AND STRONG COLD FRONT APPROACHES FROM THE WEST.
AN ANOMALOUS LOW LEVEL JET WILL TRANSPORT ABUNDANT MOISTURE
NORTHWARD INTO SNE. STRONG FORCING FOR ASCENT ACTING ON THIS
MOISTURE WILL BRING A PERIOD OF WIDESPREAD RAIN, DEVELOPING IN THE
WEST LATE THU NIGHT THEN MOVING EAST ACROSS SNE DURING FRIDAY. THE
WIND AND PWAT ANOMALIES AND MARGINAL ELEVATED INSTABILITY SUPPORT
LOCALLY HEAVY RAIN WITH SOME DOWNPOURS AND CAN'T RULE OUT AN
ISOLATED T-STORM GIVEN STRONG FORCING AT THE NOSE OF THE LOW LEVEL
JET. HOWEVER, MEAGER INSTABILITY WILL LIMIT RAINFALL RATES AND
DURATION OF HEAVY RAIN WILL BE LIMITED SO WE ARE NOT LOOKING AT AN
EXCESSIVE RAINFALL EVENT. GENERALLY WIDESPREAD RAINFALL OF 0.50 TO 1
INCH, WITH LOCALLY 1-2 INCHES POSSIBLE WHERE MORE PERSISTENT
DOWNPOURS OCCUR. WESTERN NEW ENG HAS BEST CHANCE OF MORNING COMMUTE
BEING IMPACTED BY LOCALLY HEAVY RAIN BASED ON TIMING, BUT
SIGNIFICANT FLOODING IMPACTS ARE NOT EXPECTED.
IT'S A FAIRLY FAST MOVING SYSTEM SO RAIN WILL BE TAPERING OFF DURING
THE AFTERNOON FROM WEST TO EAST AFTER THE COLD FRONT MOVES THROUGH
AND MUCH DRIER AIR MOVES IN FROM THE WEST. THE RAIN MAY END AS A
BRIEF PERIOD OF SNOW IN THE BERKSHIRES AS THE COLUMN COOLS FROM TOP
DOWN. WHILE DRIER AIR IS MOVING IN DURING THE AFTERNOON, RISK OF
SCATTERED RAIN OR SNOW SHOWERS WILL CONTINUE LATE AFTERNOON AND
EARLY EVENING AFTER THE MAIN RAIN SHIELD EXITS AS THE ROBUST UPPER
TROUGH AND COLD POOL MOVE IN FROM THE WEST.
REGARDING WIND POTENTIAL, THIS LOOKS TO BE A DECENT WIND EVENT,
ESPECIALLY FOR EASTERN NEW ENG AS A ROBUST 70-80 KT DEVELOPS 12-18Z
WITH THE JET POTENTIALLY STRENGTHENING TO 90+ KTS AS IT MOVES EAST
OVER THE CAPE/ISLANDS AROUND 18Z BEFORE MOVING OFFSHORE. WIND
ANOMALIES APPROACH +4SD AS THE JET MOVES OFFSHORE AND THE ENSEMBLE
FORECAST LOW LEVEL WIND IS NEAR THE MAXIMUM RELATIVE TO CFSR
CLIMATOLOGY. AS IS THE CASE WITH ALL SOUTHERLY LLJ EVENTS IT'S
ALWAYS ABOUT THE EXTENT OF MIXING. SOUNDINGS DO SHOW A FAIRLY STRONG
INVERSION FOR THE CAPE/ISLANDS BUT THERE ARE IMPRESSIVE PRESSURE
FALLS WHICH OFTEN HELPS TO ACCELERATE WINDS FROM ISALLOBARIC
CONTRIBUTION. ALSO TEMPS FOR THE CAPE GET INTO THE MID 50S WHICH
WILL HELP TO WEAKEN THE INVERSION SOMEWHAT. WE DECIDED TO UPGRADE TO
A HIGH WIND WARNING FOR THESE REASONS AS WELL AS THE POTENTIAL FOR A
90+ KT LOW LEVEL JET WHICH JUST TAKING 50% YIELDS GUSTS CLOSE TO
HIGH WIND CRITERIA. POTENTIAL FOR 55-65 MPH GUSTS FOCUSED FROM LATE
MORNING INTO EARLY AFTERNOON. NOW FOR THE REST OF SNE, WE CONTINUED
WIND ADVISORIES FOR 40-50 MPH GUSTS IN THE MORNING, BUT THERE IS
POTENTIAL FOR AN AREA OF ENHANCED WINDS ACROSS RI AND SE MA. THIS IS
WHERE TEMPS MAY GET CLOSE TO UPPER 50S WHICH COULD ERODE INVERSION
ENOUGH TO PRODUCE SOME 60 MPH GUSTS HERE. THIS WILL HAVE TO BE
MONITORED FOR POSSIBLE UPGRADE TO A WARNING HERE.
KEY MESSAGE 2...MUCH COLDER WITH GUSTY WEST WIND GUSTS FRIDAY
NIGHT
AFTER THE COLD FRONT MOVES THROUGH STRONG COLD ADVECTION WILL RESULT
IN WELL MIXED BOUNDARY LAYER WHICH WILL SUPPORT STRONG WEST WIND
GUSTS. THE STRONGEST GUSTS TO 40-50 MPH WILL LIKELY BE CONFINED TO
THE BERKSHIRES, WORCESTER HILLS AND ISLANDS. THERE IS A LOW RISK FOR
A FEW 50+ GUSTS. ELSEWHERE, LOOKING AT POTENTIAL FOR A PERIOD OF 35-
45 MPH GUSTS. SOUNDINGS SUPPORT STRONGER GUSTS THAN THE WIND
GUIDANCE IS SUGGESTING SO ADJUSTMENTS TO THE FORECAST MAY BE
NECESSARY. THE STRONG COLD ADVECTION WILL RESULT IN TEMPS FALLING
INTO AND THROUGH THE 20S OVERNIGHT FRI NIGHT.
KEY MESSAGE 3...COASTAL FLOOD RISK HAS ENDED
GUIDANCE IS IN AGREEMENT THAT THE CORE OF THE LOW LEVEL JET AND
STRONGEST WINDS AND SURGE WILL OCCUR AT LEAST A FEW HOURS AFTER HIGH
TIDE ON THE SOUTH COAST. AS A RESULT WE ARE NOT EXPECTING ANY
COASTAL FLOOD IMPACTS. IT WOULD TAKE ABOUT A 3 FT SURGE AT HIGH TIDE
TO PRODUCE MINOR FLOODING ALONG NARRAGANSETT AND BUZZARDS BAY. WHILE
A 3 FT SURGE AT PROVIDENCE IS POSSIBLE, WE HAVE HIGH CONFIDENCE IT
WILL OCCUR AFTER HIGH TIDE.
KEY MESSAGE 4...NEXT SYSTEM MOVES THROUGH LATE SATURDAY INTO SUNDAY
BRINGING LIGHT RAIN AND GUSTY WINDS LINGERING INTO MONDAY.
A MID-LEVEL SHORTWAVE TROUGH MOVES THROUGH LATE SATURDAY INTO SUNDAY
BRINGING SCATTERED RAIN SHOWERS TO SOUTHERN NEW ENGLAND. ANOTHER 40
TO 60 KT LOW LEVEL JET, QUICKLY FOLLOWED BY A COLD FRONT, IS
EXPECTED TO PUSH NORTH INTO SNE BY EARLY SUNDAY MORNING. WHILE THERE
IS CURRENTLY SOME UNCERTAINTY IN THE GUIDANCE ON WHERE EXACTLY THE
CORE OF THE JET WILL SET UP, THE COLD FRONT PUSHING THROUGH BEHIND
THE JET WILL PROVIDE AN OPPORTUNITY FOR EFFICIENT MIXING AND LIKELY
BRING 30 TO 40 MPH GUSTS TO AT LEAST THE COASTAL WATERS, POSSIBLY
THE CAPE AND ISLANDS, SUNDAY INTO MONDAY.
AVIATION /06Z THURSDAY THROUGH MONDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
06Z TAF UPDATE:
TODAY...HIGH CONFIDENCE
VFR. LIGHT WESTERLY WINDS 5-10 KTS SHIFT SOUTHERLY THIS AFTERNOON.
TONIGHT THROUGH FRIDAY...HIGH CONFIDENCE IN TRENDS
MVFR/IFR CEILINGS BEGIN TO CREEP IN FROM WEST TO EAST LATE TONIGHT,
WITH RAIN CHANCES BEGINNING DURING THE LATE OVERNIGHT/EARLY MORNING
HOURS. SOUTHERLY WINDS BEGIN TO INCREASE TO 10 TO 15 KTS WITH GUSTS
20 TO 30 KTS, AND WINDSHEAR ONCE AGAIN BECOMES A CONCERN OVERNIGHT
AND INTO FRIDAY MORNING WITH 2KFT WINDS AROUND 35 TO 40 KTS.
KBOS TERMINAL...HIGH CONFIDENCE IN TRENDS. MODERATE CONFIDENCE IN
TIMING.
VFR TODAY, THEN MVFR/IFR BY LATE TONIGHT/EARLY FRIDAY MORNING.
WINDSHEAR POSSIBLE OVERNIGHT AND INTO MID-FRIDAY MORNING WITH RAIN
MOVING IN BY EARLY MORNING.
KBDL TERMINAL...HIGH CONFIDENCE IN TRENDS. MODERATE CONFIDENCE IN
TIMING.
VFR TODAY, THEN MVFR/IFR BY LATE TONIGHT/EARLY FRIDAY MORNING.
WINDSHEAR POSSIBLE OVERNIGHT AND INTO MID-FRIDAY MORNING WITH RAIN
POSSIBLY MOVING IN AROUND MIDNIGHT.
OUTLOOK /FRIDAY NIGHT THROUGH MONDAY/...
FRIDAY NIGHT: VFR. STRONG WINDS WITH GUSTS UP TO 45 KT.
SATURDAY: VFR. WINDY WITH LOCAL GUSTS UP TO 30 KT.
SATURDAY NIGHT: VFR. WINDY WITH AREAS OF GUSTS UP TO 30 KT.
SUNDAY: VFR. WINDY WITH LOCAL GUSTS UP TO 30 KT. SLIGHT CHANCE
RA.
SUNDAY NIGHT THROUGH MONDAY: VFR. WINDY WITH LOCAL GUSTS UP TO
30 KT.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
GALE AND STORM WARNINGS IN EFFECT FOR FRIDAY
WINDS DECREASE AND SEAS SUBSIDE BRIEFLY DURING THE DAY TODAY.
WINDS THEN INCREASE LATE TONIGHT WITH A PERIOD OF SOUTHERLY GALE
FORCE GUSTS TO 45 KT DURING FRI MORNING AND EARLY AFTERNOON.
STORM FORCE GUSTS TO 50 KT ARE EXPECTED OVER THE WATERS ADJACENT
TO CAPE COD AS A STRONG LOW LEVEL JET MOVES THROUGH. STORM FORCE
WINDS WILL DIMINISH TO GALES BY MID-LATE AFTERNOON WITH
WESTERLY GALES CONTINUING ON ALL WATERS FRI NIGHT. SEAS INCREASE
TO 8-12 FT FRIDAY OVER THE OUTER WATERS WITH 12-15 FT POSSIBLE
FOR THE OUTER SOUTHERN WATERS.
OUTLOOK /FRIDAY NIGHT THROUGH MONDAY/...
FRIDAY NIGHT: GALE FORCE WINDS WITH LOCAL GUSTS UP TO 45 KT.
ROUGH SEAS UP TO 16 FT.
SATURDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS UP
TO 30 KT. AREAS OF ROUGH SEAS.
SATURDAY NIGHT: LOW RISK FOR GALE FORCE WINDS WITH GUSTS UP TO
35 KT. AREAS OF ROUGH SEAS.
SUNDAY: STRONG WINDS WITH GUSTS UP TO 35 KT. ROUGH SEAS UP TO
11 FT. SLIGHT CHANCE OF RAIN.
SUNDAY NIGHT: STRONG WINDS WITH GUSTS UP TO 40 KT. ROUGH SEAS
UP TO 12 FT.
MONDAY: STRONG WINDS WITH GUSTS UP TO 35 KT. AREAS OF ROUGH
SEAS.
BOX WATCHES/WARNINGS/ADVISORIES
CT...WIND ADVISORY FROM 4 AM FRIDAY TO 1 AM EST SATURDAY FOR
CTZ002>004.
MA...WIND ADVISORY FROM 4 AM FRIDAY TO 1 AM EST SATURDAY FOR
MAZ002>021-026.
HIGH WIND WARNING FROM 7 AM TO 3 PM EST FRIDAY FOR MAZ022>024.
RI...WIND ADVISORY FROM 4 AM FRIDAY TO 1 AM EST SATURDAY FOR
RIZ001>008.
MARINE...GALE WARNING FROM 5 AM FRIDAY TO 7 AM EST SATURDAY FOR ANZ230-
250-251.
STORM WARNING FROM 9 AM TO 3 PM EST FRIDAY FOR ANZ231>234-254-
255.
GALE WARNING FROM 3 AM FRIDAY TO 7 AM EST SATURDAY FOR ANZ235-
237-256.
GALE WARNING FROM 5 AM FRIDAY TO 1 AM EST SATURDAY FOR ANZ236.
DISCUSSION...KJC/MCMINN
AVIATION...MCMINN
MARINE...KJC/MCMINN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page