203
FXUS61 KBOX 301951
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
251 PM EST FRI JAN 30 2026
WHAT HAS CHANGED
- COLD WEATHER ADVISORIES HAVE BEEN EXTENDED INTO FRIDAY NIGHT AND
SATURDAY MORNING FOR HAZARDOUS WIND CHILLS.
- A WINTER STORM WATCH CONTINUES FOR CAPE COD AND THE ISLANDS, WITH
THE RISK OF ACCUMULATING SNOW AND STRONG WINDS SUNDAY CONFINED TO
THIS AREA, FROM A POWERFUL OFFSHORE WINTER STORM.
- THE POTENTIAL FOR WIDESPREAD MODERATE COASTAL FLOODING HAS
DECREASED DUE TO A MORE OFFSHORE STORM TRACK.
- GALE WARNINGS HAVE BEEN ISSUED FOR THE NEARSHORE WATERS
INCLUDING BOSTON HARBOR AND NARRAGANSETT BAY.
KEY MESSAGES
- FRIGID TEMPERATURES TONIGHT INTO SATURDAY MORNING.
- A POWERFUL OCEAN STORM LOOKS MORE LIKELY TO PASS FARTHER OFFSHORE
OF SOUTHERN NEW ENGLAND SUNDAY INTO SUNDAY NIGHT. GREATEST OVERALL
IMPACTS FROM ACCUMULATING SNOW AND STRONG WINDS WILL BE ACROSS
SOUTHEAST COASTAL PLYMOUTH COUNTY, CAPE COD AND THE ISLANDS SUNDAY
AND SUNDAY NIGHT. MUCH LIGHTER ACCUMULATING SNOW WITH LESSER OVERALL
IMPACT FURTHER INLAND INTO SOUTHEAST MA, WITH LITTLE IF ANY IMPACT
INTO THE BOSTON-PROVIDENCE CORRIDOR SUNDAY.
- MINOR TO PERHAPS MODERATE COASTAL FLOODING SUNDAY INTO MONDAY
ALONG THE EASTERN MASSACHUSETTS COAST.
DISCUSSION
KEY MESSAGE 1...FRIGID TEMPERATURES ONCE AGAIN TONIGHT INTO SATURDAY
MORNING.
COLD WEATHER ADVISORIES HAVE BEEN EXTENDED INTO TONIGHT AND SATURDAY
MORNING, WITH ACTUAL AIR TEMPS FALLING TO ZERO TO MINUS 10 ACROSS
THE REGION! THESE TEMPS WERE DERIVED FROM THE NBM AND THE COLDER MOS
GUIDANCE, GIVEN LIGHT WINDS TONIGHT. HOWEVER, A SUFFICIENT LIGHT WNW
BREEZE AT 5-10 MPH TO GENERATE COLDER WIND CHILLS FROM MINUS 10 TO
MINUS 15, WHICH MEETS OUR EXTREME COLD ADVISORY CRITERIA. HENCE, WE
EXTENDED THE COLD WEATHER ADVISORY INTO TONIGHT/EARLY SAT MORNING
FOR MOST OF RI/MA/CT. WE EXCLUDED THE SOUTH COAST AS WIND CHILLS
THERE ARE MORE IN THE ZERO TO MINUS 5 RANGE. STILL VERY COLD, BUT
SHY OF CRITERIA. NONETHELESS, DANGEROUS COLD FOR ANYONE OUTDOORS
TONIGHT/EARLY SATURDAY.
KEY MESSAGE 2...12Z MODELS CONTINUE THE TREND FROM THE OVERNIGHT
GUIDANCE, TRACKING A POWERFUL VERTICALLY STACKED LOW (SUB 970 MB) A
FAIRLY GOOD DISTANCE SOUTHEAST OF THE 40N/70W BENCHMARK. HOWEVER,
GIVEN ITS VERY LARGE CIRCULATION AND PRECIP SHIELD, COMBINED WITH
OCEAN EFFECT SNOW (OES) BANDS, ALONG WITH POSSIBLE 850-700 MB FGEN
SNOW BANDS CLIPPING THE CAPE AND ISLANDS, WE DECIDED TO HOLD WITH
THE WINTER STORM WATCH FOR THIS REGION. SUFFICIENT GUIDANCE
SUPPORTING 0.3 TO 0.6 INCHES OF QPF OVER THIS AREA, WHICH INCLUDES
THE 3KM NAM, CANADIAN, ICON, AI MODELS AND SOME ENSEMBLE MEMBERS.
THEREFORE THIS SUPPORTS A RISK OF 4-7" ACROSS THE CAPE AND ISLANDS,
WITH HIGHEST TOTALS OVER ACK AND THE OUTER CAPE GIVEN OES
ENHANCEMENT. AS WE KNOW, NORTHWEST OF THE MID LEVEL FGEN BANDS,
THERE IS STRONG SUBSIDENCE. THUS, A SHARP CUTOFF IN ACCUMULATING
SNOW NORTHWEST OF THE CAPE COD CANAL. HENCE, WE LOWERED SNOW TOTALS
OVER SOUTHEAST MA TO 1-2", UP TO 3" SOUTHEAST COASTAL PLYMOUTH
COUNTY GIVE OES. THEN AN INCH OR LESS IN THE BOSTON-PROVIDENCE
CORRIDOR, WITH A SHUTOUT WESTWARD INTO CT/WESTERN-CENTRAL MA. SNOW
WILL ADVANCE SOUTH TO NORTH EARLY SUNDAY MORNING AND CONTINUING
THROUGH THE DAY AND INTO SUNDAY NIGHT.
REGARDING WINDS, DESPITE THE LOW TRACKING WELL SOUTHEAST OF THE
40N/70W BENCHMARK, THE SUB 970 MB LOW AND ITS LOW LEVEL NNE JET WILL
SCRAP CAPE COD AND THE ISLANDS WITH 50-55 KT AT 925 MB SUNDAY
AFTERNOON. MODEL SOUNDINGS INDICATE NNE WINDS GUSTING UP TO 45 KT/50
MPH ARE POSSIBLE ACROSS THE CAPE AND ISLANDS, WITH LESS WIND
NORTHWEST OF THE CANAL, WITH DIMINISHING WIND FIELD ALOFT COMBINED
WITH A MORE NORTHERLY WIND TRAJECTORY THERE. THESE WIND SPEEDS ARE
COVERED IN THE WINTER STORM WATCH.
KEY MESSAGE 3...MINOR TO PERHAPS MODERATE COASTAL FLOODING SUNDAY
INTO MONDAY ALONG THE EASTERN MASSACHUSETTS COAST.
THE POTENTIAL FOR WIDESPREAD MODERATE COASTAL FLOODING HAS DECREASED
DUE TO A MORE OFFSHORE STORM TRACK, BUT AREAS OF MODERATE FLOODING
SHOULD BE LIMITED TO LOCATIONS SOUTH OF BOSTON, ESPECIALLY ON CAPE
COD (BAY SIDE), MARTHA'S VINEYARD, AND NANTUCKET, AND IS MORE LIKELY
DURING THE SUNDAY EVENING AND MIDDAY MONDAY HIGH TIDES.
ENSEMBLE GUIDANCE STILL SHOWS LARGE RANGES IN POSSIBLE WATER LEVELS
FOR NANTUCKET AND DENNIS, WHICH IS TIED TO UNCERTAINTY IN STORM
TRACK AND TIMING OF THE HIGHEST SURGE. FARTHER NORTH, THESE FORECAST
RANGES ARE MUCH SMALLER WHICH INDICATES HIGHER CONFIDENCE IN MINOR
FLOODING IMPACTS FROM BOSTON TO THE MERRIMACK RIVER.
SINCE WE STILL HAVE A GOOD AMOUNT OF UNCERTAINTY, WE DECIDED TO
MAINTAIN THE COASTAL FLOOD WATCH. IF THE STORM TRENDS EVEN FARTHER
OFFSHORE, WATER LEVELS AND IMPACTS WOULD BE LOWER THAN CURRENTLY
FORECAST, AND WOULD LIKELY RESULT IN MINOR IMPACTS FOR MUCH OF THE
COASTLINE. ADDITIONALLY, THE TIMING OF THE HIGHEST SURGE APPEARS TO
BE NEAR LOW TIDE SUNDAY AFTERNOON, BUT IF IT IS DELAYED (OR ARRIVES
SOONER) IT WOULD COINCIDE CLOSER TO HIGH TIDE AND WOULD LEAD TO
HIGHER WATER LEVELS AND GREATER IMPACTS, ALTHOUGH A REASONABLE HIGH-
END SCENARIO WOULD STILL BE WITHIN THE MODERATE FLOOD CATEGORY.
AS A REMINDER:
MINOR FLOODING REFERS TO SHALLOW FLOODING UP TO 1 FOOT DEEP AND CAN
RESULT IN TEMPORARY ROAD CLOSURES ON MORE VULNERABLE COASTAL ROADS.
MODERATE FLOODING REFERS TO FLOODING 1 TO 3 FEET DEEP AND CAN CAUSE
MORE WIDESPREAD ROAD CLOSURES, DAMAGE TO SHOREFRONT PROPERTY, AND
DEBRIS ON COASTAL ROADS FROM LARGE WAVES. VEHICLES LEFT IN FLOOD
PRONE AREAS CAN ALSO BE FLOODED.
AVIATION /19Z FRIDAY THROUGH WEDNESDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
18Z UPDATE...
THROUGH SATURDAY...HIGH CONFIDENCE.
VFR THROUGH SATURDAY, ALONG WITH DRY WEATHER. GUSTY WEST WINDS
UP TO 30 KT AT TIMES FRIDAY AFTERNOON, DIMINISH WITH SUNSET,
THEN BECOMING LIGHT WNW TONIGHT AND SATURDAY.
SATURDAY NIGHT...MODERATE CONFIDENCE.
VFR AND DRY WEATHER, BUT MVFR/VFR CIGS ARRIVE TOWARD MORNING IN
EASTERN MA.
SUNDAY/SUN NIGHT...MODERATE CONFIDENCE.
PERIODS OF LIGHT SNOW/FLURRIES THIS PERIOD WITH A COMBINATION OF
MVFR/VFR CONDITIONS. NORTH WINDS 15-25 KT SUNDAY, BECOME NNW SUN
NIGHT.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF THRU SATURDAY.
GUSTY WEST AT 20-25 KNOTS DIMINISH WITH SUNSET. LIGHT WNW WINDS
TONIGHT AND SATURDAY.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF THROUGH SATURDAY.
OUTLOOK /MONDAY THROUGH WEDNESDAY/...
MONDAY THROUGH MONDAY NIGHT: VFR. BREEZY.
TUESDAY THROUGH TUESDAY NIGHT: VFR.
WEDNESDAY: VFR. SLIGHT CHANCE SN.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
* MODERATE TO HEAVY FREEZING SPRAY DEVELOPING ON THE WATERS TONIGHT
INTO FRIDAY
* DANGEROUS MARINE CONDITIONS DEVELOPING SUNDAY
A PERIOD OF WNW GUSTS TO 25-30 KT WILL CONTINUE TODAY, THEN
DIMINISHING WIND TONIGHT. THE GUSTY WINDS WILL BE ACCOMPANIED
BY A REINFORCING SHOT OF ARCTIC AIR WHICH WILL RESULT IN
WIDESPREAD MODERATE FREEZING SPRAY WITH AREAS OF HEAVY FREEZING
SPRAY OVER SOME OF THE NEARSHORE WATERS. SIGNIFICANT ACCRETION
OF ICE IS EXPECTED ON VESSELS OVER THE WATERS. FREEZING SPRAY
ADVISORIES AND HEAVY FREEZING SPRAY WARNINGS REMAIN IN EFFECT.
OUR ATTENTION TURNS TO A POWERFUL OCEAN STORM WHICH TRACKS WELL
SOUTH AND EAST OF THE WATERS ON SUNDAY. POTENTIAL FOR STORM
FORCE NE GUSTS TO 50-55 KT OVER THE OUTER WATERS PEAKING DURING
SUNDAY, WITH 40-50 KT GUSTS OVER NEARSHORE WATERS. SEAS EXPECTED
TO BUILD TO 20+ FT ON THE WATERS EAST OF CAPE COD RESULTING IN
DANGEROUS CONDITIONS FOR MARINERS. IN ADDITIONS, AREAS OF LIGHT
TO MODERATE FREEZING SPRAY WILL DEVELOP SAT NIGHT THOUGH SUN
NIGHT.
OUTLOOK /MONDAY THROUGH WEDNESDAY/...
MONDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS UP
TO 30 KT. ROUGH SEAS UP TO 16 FT. FREEZING SPRAY LIKELY.
MONDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF ROUGH SEAS.
TUESDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING 5 FT.
TUESDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING
5 FT.
WEDNESDAY: WINDS LESS THAN 25 KT. SLIGHT CHANCE OF SNOW.
BOX WATCHES/WARNINGS/ADVISORIES
CT...COLD WEATHER ADVISORY FROM 7 PM THIS EVENING TO 10 AM EST
SATURDAY FOR CTZ002>004.
MA...COLD WEATHER ADVISORY FROM 7 PM THIS EVENING TO 10 AM EST
SATURDAY FOR MAZ002>019-026.
COASTAL FLOOD WATCH FROM SUNDAY MORNING THROUGH MONDAY
AFTERNOON FOR MAZ007-015-016-019-022>024.
WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH LATE
SUNDAY NIGHT FOR MAZ022>024.
RI...COLD WEATHER ADVISORY FROM 7 PM THIS EVENING TO 10 AM EST
SATURDAY FOR RIZ001>004.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR ANZ230-
236.
GALE WARNING FROM 7 AM SUNDAY TO 1 AM EST MONDAY FOR ANZ230.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
ANZ231>235-237-251.
FREEZING SPRAY ADVISORY UNTIL 1 AM EST SATURDAY FOR ANZ231-235-
237-250-251-254-256.
STORM WATCH FROM SUNDAY MORNING THROUGH LATE SUNDAY NIGHT FOR
ANZ231-232-250-254>256.
HEAVY FREEZING SPRAY WARNING UNTIL 1 AM EST SATURDAY FOR
ANZ232>234-255.
GALE WARNING FROM 6 AM SUNDAY TO 1 AM EST MONDAY FOR ANZ233-
234.
GALE WARNING FROM 3 AM SUNDAY TO 1 AM EST MONDAY FOR ANZ235-
237.
FREEZING SPRAY ADVISORY UNTIL 7 PM EST THIS EVENING FOR ANZ236.
GALE WARNING FROM 5 AM TO 11 PM EST SUNDAY FOR ANZ236.
SMALL CRAFT ADVISORY UNTIL 1 AM EST SATURDAY FOR ANZ250-
254>256.
GALE WARNING FROM 6 AM SUNDAY TO 4 AM EST MONDAY FOR ANZ251.
DISCUSSION...MCMINN/JWD/NOCERA
AVIATION...JWD/NOCERA
MARINE...JWD/NOCERA
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