430
FXUS61 KBOX 141120
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
620 AM EST SUN DEC 14 2025
SYNOPSIS
FAST MOVING LOW PRESSURE WILL BRING ACCUMULATING SNOW TO THE
REGION INTO MIDDAY ESPECIALLY SOUTH OF THE MASSACHUSETTS
TURNPIKE. THE SNOW WILL LINGER INTO THE AFTERNOON ACROSS RHODE
ISLAND AND ESPECIALLY ACROSS FAR EASTERN MASSACHUSETTS WHERE IT
MAY PERSIST INTO THIS EVENING. A BRIEF SHOT OF ARCTIC
AIR FOLLOWS TONIGHT INTO MONDAY, WITH WIND CHILL VALUES
DROPPING TO BETWEEN 0 TO 10 BELOW ZERO. COLD WEATHER CONTINUES
MONDAY NIGHT INTO TUESDAY BUT WITH MUCH LIGHTER WINDS. A WARMING
TREND BEGINS WEDNESDAY AND ESPECIALLY BY THURSDAY WHEN HIGH
TEMPERATURES OF 50+ ARE POSSIBLE. UNSEASONABLY MILD TEMPERATURES
WILL BE ACCOMPANIED BY A ROUND OF SHOWERS SOMETIME LATER
THURSDAY INTO EARLY FRIDAY WITH PERHAPS A PERIOD OF STRONG
SOUTHERLY WINDS AND HEAVY RAIN. A BRIEF SHOT OF MUCH COLDER
WEATHER WITH ANOTHER PERIOD OF STRONG WINDS POSSIBLE LATER
FRIDAY INTO SATURDAY.
NEAR TERM /UNTIL 6 PM THIS EVENING/
KEY MESSAGES...
* ACCUMULATING SNOW ENDS BY LUNCHTIME ACROSS WESTERN MA/CT, BUT
PERSISTS INTO THE AFTERNOON ESPECIALLY ACROSS EASTERN MA
* HOURLY SNOWFALL RATES GENERALLY ON THE LIGHTER SIDE...BUT
BRIEF BURSTS OF MODERATE SNOW POSSIBLE NEAR THE SOUTH COAST
TREND IN HIGH RES GUIDANCE HAS BEEN TO SHIFT THE TIMING OF THE END
OF THE STEADIEST SNOW FROM MID MORNING TO THE AFTERNOON FOR MUCH OF
RHODE ISLAND AND EASTERN MASSACHUSETTS. MODEL GUIDANCE, NAMELY THE
HRRR AND NAM3KM HAVE ALSO BEGUN TO RESOLVE AN INVERTED TROUGH AND
WRAP AROUND OCEAN EFFECT SNOW EXTENDING FROM LOW PRESSURE AS IT
PULLS AWAY. TROUGH WILL BE A GOOD FOCUS FOR VERTICAL MOTION AND
MOISTURE AS OMEGA INCREASES TO -10 TO -15 UBAR/SEC. SHARPLY COLDER
AIR FILTERING BEHIND DEPARTING LOW PRESSURE WILL INTRODUCE NON-ZERO
MLCAPE VALUES WHICH COULD HELP WITH OCEAN ENHANCEMENT OF ANY
SNOWBANDS. DESPITE THESE FAVORABLE PARAMETERS, DAYTIME WILL LIKELY
BE LIMITED BY MARGINAL SFC TEMPS IN THE MID AND EVEN UPPER 30S.
TEMPS MAY BE LOCALLY LOWER UNDER ANY OCEAN EFFECT BANDS BUT ITS
REALLY GOING TO TAKE CONSIDERABLE RATES TO COOL THE PBL FROM THE
INFLUENCE OF 45-47F WATER TEMPS. AS A RESULT, STILL THINK THAT
ADVISORY LEVEL SNOW TOTALS 2-4" FOR RI/SE MA WITH LOCALIZED 5-6"
AMOUNTS POSSIBLE NEAR THE SOUTH COAST AND CAPE COD.
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/
KEY MESSAGES...
* VERY COLD WITH WIND CHILL VALUES NEAR OR BELOW ZERO
* WINDY CONDITIONS WITH GUSTS UP TO 40 MPH SUNDAY NIGHT AND MONDAY
THE COLDEST AIRMASS OF THE SEASON THUS FAR WILL MOVE IN BEHIND THE
SNOW FOR SUNDAY NIGHT AS 850MB TEMPS CRASH INTO THE -15C TO
-20C RANGE. THIS WILL RESULT IN OVERNIGHT LOW TEMPERATURES BOTTOMING
OUT IN THE SINGLE DIGITS ACROSS THE INTERIOR, TO THE LOW TEENS NEAR
THE COASTAL PLAIN. A STRONG PRESSURE GRADIENT WILL RESULT IN GUSTY
WINDS OVERNIGHT, AROUND 25-40 MPH. THIS WILL BRING THE WINDCHILL
INDEX/FEELS-LIKE TEMPERATURES DOWN TO THE 0F TO -5F RANGE, WITH -5F
TO -15F IN THE HIGH TERRAIN.
MONDAY
HIGH PRESSURE HELPS TO KEEP AN ARCTIC AIR MASS IN PLACE THROUGH THE
DAY ON MONDAY AS GFS AND EURO ENSEMBLES KEEP TEMPERATURE ANOMALIES
NEAR 10 DEGREES COLDER THAN NORMAL. OTHER STORY MONDAY WILL BE A
STEEP PRESSURE GRADIENT KEEPING A STIFF NW WIND IN PLACE FOR THE
REGION. WIND GUSTS BETWEEN 25 AND 35 MPH WILL MAKE HIGH TEMPERATURES
IN THE TEENS (AT HIGHER ELEVATIONS) AND 20S ELSEWHERE FEEL MORE LIKE
THE SINGLE DIGITS TO LOWER TEENS AT THEIR WARMEST.
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/
KEY MESSAGES...
* A FEW BRIEF SNOW SHOWERS POSSIBLE MON NIGHT, OTHERWISE DIMINISHING
WINDS WITH LOW TEMPS MAINLY IN THE TEENS
* DRY & CHILLY TUE...HIGHS MAINLY IN THE LOWER TO MIDDLE 30S
* TURNING MILDER WED WITH CONTINUED DRY WEATHER & HIGHS INTO THE 40S
* SHOWERS WITH HEAVY RAIN & POTENTIAL BRIEFLY STRONG SOUTHERLY WIND
GUSTS LATER THU INTO EARLY FRI WITH UNSEASONABLY MILD TEMPS
* BRIEF SHOT OF MUCH COLDER TEMPS RETURNS BEHIND THE FRONT LATER FRI
INTO SAT WITH ANOTHER ROUND OF STRONG WINDS POSSIBLE
DETAILS...
MONDAY NIGHT INTO TUESDAY...
A WEAK SHORTWAVE MAY BRING A FEW BRIEF SNOW SHOWERS TO THE REGION
MONDAY NIGHT. OTHERWISE...STILL CHILLY MON NIGHT INTO TUE BUT WITH
LIGHT WINDS. LOW TEMPERATURES MON NIGHT WILL MAINLY BE IN THE TEENS.
HIGHS ON TUE WILL RANGE FROM THE UPPER 20S IN THE HIGHEST TERRAIN TO
MAINLY THE LOWER TO MIDDLE 30S ELSEWHERE.
WEDNESDAY...
THE DEVELOPING -PNA AND HIGH PRESSURE TO OUR SOUTH SLIDING FURTHER
EAST WILL ALLOW FOR THE BEGINNING OF A PATTERN CHANGE AND MILDER
TEMPERATURES. WHILE IT WILL REMAIN DRY ON WED, GUSTY SOUTHWEST WINDS
DEVELOPING WILL PUSH HIGH TEMPERATURES WELL INTO THE 40S.
THURSDAY INTO FRIDAY MORNING...
STRONG SHORTWAVE ENERGY OVER THE NORTHERN PLAINS WILL MOVE EASTWARD
INTO THE GREAT LAKES. AS THIS HAPPENS...STRONG SURFACE LOW PRESSURE
PERHAPS SUB 980 MB WILL PASS WELL TO OUR NORTH ACROSS QUEBEC. GIVEN
THE POTENTIAL STRENGTH OF THE SURFACE LOW PRESSURE SYSTEM...THE LONG
RANGE GUIDANCE IS INDICATING A STRONG SOUTHERLY LLJ NEARLY 3
STANDARD DEVIATIONS OUTSIDE CLIMATOLOGY. NOT ONLY WILL THIS BRING UP
UNSEASONABLY MILD TEMPERATURES AND PWATS EXCEEDING 1 INCH. THIS WILL
COMBINED WITH STRONG FORCING AHEAD OF THE COLD FRONT AND BRING
SHOWERS WITH PERHAPS BRIEF HEAVY RAIN SOMETIME LATER THU INTO FRI.
IN ADDITION...GIVEN THE MAGNITUDE OF THE SOUTHERLY LLJ WE WILL HAVE
TO WATCH FOR A BRIEF PERIOD FOR STRONG SURFACE WIND GUSTS IF THE
INVERSION IS ABLE TO MIX OUT. IT IS WAY TOO EARLY TO ASSESS
THAT...BUT DEPENDING ON THE TIMING TEMPERATURES MAY RISE WELL INTO
THE 50S THU NIGHT/EARLY FRI AND MAY EVEN FLIRT WITH 60 DEGREES. IF
WE ARE ABLE TO GET MILD ENOUGH...THE POTENTIAL FOR A PERIOD OF
STRONG WINDS TO BE REALIZED WILL INCREASE. AGAIN...WAY TOO EARLY TO
SAY MUCH MORE THAN THAT BUT SOMETHING TO WATCH IN THE COMING DAYS.
LATER FRIDAY INTO SATURDAY...
BRIEFLY TURNING MUCH COLDER LATER FRIDAY INTO SATURDAY BEHIND THE
COLD FRONT. MAINLY DRY WEATHER EXPECTED, BUT ANOTHER PERIOD OF STRONG
WINDS THIS TIME FROM THE WEST IS POSSIBLE IMMEDIATELY BEHIND THE
COLD FRONT.
AVIATION /12Z SUNDAY THROUGH THURSDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
12Z TAF UPDATE..
TODAY...MODERATE CONFIDENCE
LIGHT SNOW WILL RESULT IN A LOT OF IFR CONDITIONS THIS MORNING
WITH VSBYS IN THE 1-3 MILE RANGE. BANDS OF MODERATE SNOW AND AND
LIFR CONDITIONS SHOULD MAINLY BE CONFINED TO RI/SE MA. THE LIGHT
SNOW WILL END ACROSS WESTERN MA/CT BY LUNCHTIME, BUT LINGER INTO
THE AFTERNOON EAST OF THE CT RIVER VALLEY ESPECIALLY ACROSS
EASTERN MA. SO IMPROVEMENT TO MVFR AND EVEN VFR CONDITIONS WILL
BE CONFINED TO MAINLY INTERIOR SOUTHERN NEW ENGLAND THIS
AFTERNOON.
TONIGHT...HIGH CONFIDENCE
MVFR-IFR AND EVEN BRIEF LIFR CONDITIONS ARE EXPECTED IN AREAS
TOWARDS THE CAPE AND ISLANDS IN OCEAN EFFECT SNOW SHOWERS. THIS
ACTIVITY SHOULD DISSIPATE THOUGH AFTER MIDNIGHT. OTHERWISE, NW
WIND GUSTS OF 20 TO 25 KNOTS WITH A FEW GUSTS NEAR 30 KNOTS
ACROSS THE HIGH TERRAIN AND NEAR THE COAST DEVELOP TONIGHT.
MONDAY...HIGH CONFIDENCE
MAINLY VFR WITH NW GUSTS OF 30-35 KNOTS. A FEW CU BUT SHOULD BE
ABOVE MVFR CEILINGS.
KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. LIGHT SNOW CONTINUES
MUCH OF THE DAY WITH VSBYS GENERALLY IN THE 1-3 MILE RANGE. THE
STEADY LIGHT SNOW SHOULD FINALLY COME TO AN END BY LATE
AFTERNOON/EARLY EVENING. TOTAL SNOW ACCUMULATIONS OF 1-3".
KBDL TERMINAL...MODERATE CONFIDENCE IN TAF. LIGHT SNOW ENDS BY
LUNCHTIME WITH SNOW ACCUMULATIONS OF 1-2" EXPECTED.
OUTLOOK /MONDAY NIGHT THROUGH THURSDAY/...
MONDAY NIGHT: VFR. BREEZY. SLIGHT CHANCE SHSN.
TUESDAY: VFR.
TUESDAY NIGHT: VFR. BREEZY.
WEDNESDAY: VFR. WINDY WITH AREAS OF GUSTS UP TO 30 KT.
WEDNESDAY NIGHT THROUGH THURSDAY: VFR. BREEZY.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TODAY THROUGH MONDAY NIGHT ...HIGH CONFIDENCE.
LIGHT N/NW WINDS THROUGH THE EARLY AFTERNOON. WINDS QUICKLY INCREASE
TO GALES AROUND 21Z AND GALES CONTINUE THROUGH 20Z MONDAY. STRONG
COLD ADVECTION ALLOWS FOR AMPLE MIXING RESULTING IN WIND GUSTS
BETWEEN 35-40KTS SUNDAY EVENING THROUGH MONDAY AFTERNOON. AREAS OF
VERY LIGHT FREEZING SPRAY POSSIBLE 00Z MONDAY - 19Z MONDAY.
ELSEWHERE, SMALL CRAFT ADVISORY CONDITIONS EXPECTED IN NARRAGANSETT
BAY AND BOSTON HARBOR.
OUTLOOK /MONDAY NIGHT THROUGH THURSDAY/...
MONDAY NIGHT: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH
GUSTS UP TO 25 KT. LOCAL ROUGH SEAS. SLIGHT CHANCE OF SNOW
SHOWERS.
TUESDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING 5 FT.
TUESDAY NIGHT: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH
GUSTS UP TO 30 KT. SEAS LOCALLY APPROACHING 5 FT.
WEDNESDAY: STRONG WINDS WITH GUSTS UP TO 30 KT. AREAS OF ROUGH
SEAS.
WEDNESDAY NIGHT: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH
GUSTS UP TO 25 KT. LOCAL ROUGH SEAS.
THURSDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS UP
TO 30 KT. AREAS OF SEAS APPROACHING 5 FT.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
MAZ017>024.
RI...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
RIZ001>008.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 3 PM EST
MONDAY FOR ANZ230-236.
GALE WARNING FROM 7 PM THIS EVENING TO 1 PM EST MONDAY FOR
ANZ231>235-237-250-251-254>256.
SYNOPSIS...FT/FRANK
NEAR TERM...FT
SHORT TERM...FT
LONG TERM...FRANK
AVIATION...FT/FRANK
MARINE...FT/FRANK
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