456
FXUS61 KBOX 312322
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
622 PM EST WED DEC 31 2025
WHAT HAS CHANGED
WINTER WEATHER ADVISORY EXPANDED ACROSS SOUTHERN NEW ENGLAND DUE TO
THE POTENTIAL FOR OROGRAPHIC ENHANCEMENT ALONG THE WESTERN HILLS.
SNOWFALL TRENDING LOWER ACROSS THE ISLANDS, POTENTIAL FOR RAIN TO
MIX WITH SNOW ON NANTUCKET HAS LOWERED TOTALS, WHICH LEAD TO THE
CANCELLATION OF THE WINTER WEATHER ADVISORY ON THE ISLAND.
KEY MESSAGES
- LIGHT TO MODERATE SNOWFALL THIS EVENING THROUGH EARLY TOMORROW
MORNING, POSSIBLY ENDING WITH A SNOW SQUALL DUE TO AN INCOMING
ARCTIC COLD FRONT.
- VESSEL ICING DUE TO ACCRETION OF LIGHT FREEZING SPRAY OVER THE
WATERS IS POSSIBLE THURSDAY NIGHT INTO THIS WEEKEND.
- INCREASING CHANCE FOR SNOW SHOWERS ON SUNDAY, OTHERWISE NO CHANGES.
DISCUSSION
KEY MESSAGE 1...LIGHT TO MODERATE SNOWFALL THIS EVENING THROUGH
EARLY TOMORROW MORNING, POSSIBLY ENDING WITH A SNOW SQUALL DUE TO AN
INCOMING ARCTIC COLD FRONT.
BOTTOM LINE UP FRONT: SNOW OVERSPREADS THE REGION BETWEEN 10PM TO
MIDNIGHT WEST, AND MIDNIGHT TO 2AM EAST, HEAVIEST SNOWFALL OVERNIGHT
2AM TO 6AM THURSDAY. IF YOUR PLANS FOR CELEBRATING THE NEW YEAR
INCLUDE TRAVEL BY CAR, PLEASE TAKE IT SLOWLY WHEN YOU RETURN HOME.
ROADWAYS WILL BECOME SNOW COVERED QUICKLY GIVEN THE ANTECEDENT
CONDITIONS.
WHAT'S NEW: GUIDANCE OVER THE LAST 24-HOURS HAS SHOWN A SUBTLE SHIFT
IN WIND DIRECTION TO THE SOUTHWEST FROM THE WEST-SOUTHWEST. AS FOR
NANTUCKET, CONSENSUS HAS GROWN IN A PRIMARY WIND DIRECTION OUT OF
THE SOUTH-SOUTHWEST, LENDING A "WARMER" OUTCOME, LEADING TO RAIN
MIXING IN WITH SNOW OVERNIGHT, THUS LOWERING TOTALS. OPT'D TO CANCEL
THE WINTER WEATHER ADVISORY HERE - THOUGH, THOSE TRAVELING TONIGHT
ON THE ISLAND SHOULD EXPECT MINOR SNOW ACCUMULATION AROUND AN INCH
OR LESS. WITH THE RAIN, SOME OF THE ACCUMULATIONS COULD WASH AWAY BY
MORNING AND FALLING AFTERNOON TEMPERATURES COULD LEAD TO ICY ROADS
IF UNTREATED. WITH A SHIFT IN THE PREVAILING WIND TO THE SOUTHWEST,
SNOWFALL AXIS HAS SHIFTED FURTHER NORTH. WILL DISCUSS FURTHER BELOW,
BUT EXPANDED THE WINTER WEATHER ADVISORY TO INCLUDE; WESTERN ZONES
OF FRANKLIN AND HAMPSHIRE COUNTIES, WORCESTER COUNTY, TOLLAND AND
WINDHAM COUNTIES, MOST OF RHODE ISLAND, AND ALL OF SOUTHEAST
MASSACHUSETTS. HERE WE FEEL THERE IS THE BEST POTENTIAL FOR 2-4"
WITH THE HIGHER OF THE TOTALS ON THE WESTERN FACING HILLS, DUE TO
UPSLOPING FROM THE SOUTHWEST FLOW.
FORECAST DETAILS: QUIET THROUGH THE REST OF THE DAYLIGHT HOURS, THEN
A ROBUST 850MB SHORTWAVE RACES THROUGH SOUTHERN NEW ENGLAND THIS
EVENING THROUGH EARLY TOMORROW MORNING. THIS FEATURE HAS NEAR NORMAL
MOISTURE TO WORK WITH, PWATS OF 0.3" TO 0.4" DOESN'T SOUND OVERLY
TOO IMPRESSIVE, BUT IS ENOUGH TO WORK WITH. LOOKING THROUGH BUFKIT
FORECAST SOUNDINGS, THERE IS GOOD SATURATION AND OMEGA/LIFT IN THE
DENDRITIC GROWTH ZONE (DGZ), WITH LIGHT TO MODERATE SNOW FOR SEVERAL
HOURS 2AM TO 6AM. HREF SUPPORTIVE OF THIS IDEA, WITH PROBABILITIES
BETWEEN 30% AND 60% FOR SNOWFALL RATES 1+" AN HOUR DURING THIS TIME
ACROSS CONNECTICUT, RHODE ISLAND, AND SOUTHEAST MASSACHUSETTS. AS
MENTIONED ABOVE, THOSE TRAVELING LATE TONIGHT OR TOMORROW MORNING
WILL WANT TO PLAN ACCORDINGLY AS SLICK TRAVEL IS EXPECTED. THERE IS
A LEVEL OF UNCERTAINTY AROUND HOW FAR NORTH THE WARM AIR REACHES,
FOR THE TIME BEING CONFIDENCE FOR THE NORTHERN EXTENT IS NANTUCKET.
IT IS THERE THE BEST CHANCE FOR RAIN TO MIX WITH THE SNOW.
ELSEWHERE, REMAINS COLD ENOUGH TO STAY SNOW. ADDITIONALLY, SOUTHWEST
FLOW ENHANCES SNOW POTENTIAL DUE TO OROGRAPHIC LIFT/UPSLOPE ALONG
WESTERN FACING HILLS OF NORTHEASTERN CONNECTICUT, CENTRAL
MASSACHUSETTS... EVEN WESTERN HILLS OF RHODE ISLAND BENEFIT FROM AN
UPSLOPE COMPONENT. FINALLY, THE SHORTWAVE MOVES OFF SHORE EARLY
THURSDAY MORNING, FOLLOWED WITH AN ARCTIC FRONT MIDMORNING, WITH
ADDITIONAL SNOW SHOWERS OR POSSIBLY SNOW SQUALLS.
POST: CAA BRINGS FALLING TEMPERATURES INTO THE AFTERNOON, LOWERING
INTO THE 20S AND TEENS DURING THE AFTERNOON. SOUTHWEST WIND SHIFTS
TO THE NORTHWEST WITH GUSTS REACHING BETWEEN 30 TO 40 MPH. DRY AND
COLD WEATHER EXPECTED THURSDAY AFTERNOON AND OVERNIGHT. NIGHTTIME
LOWS DIP FURTHER, REACHING DOWN INTO THE TEENS AND UPPER SINGLE
DIGITS.
KEY MESSAGE 2...VESSEL ICING DUE TO ACCRETION OF LIGHT FREEZING
SPRAY OVER THE WATERS IS POSSIBLE THURSDAY NIGHT INTO THIS WEEKEND.
MOSTLY FOR MARINE INTERESTS, BUT WITH A PROLONGED PERIOD OF COLD AIR
OVER THE RELATIVELY MILDER OCEAN WATERS, PERIODS OF FREEZING SPRAY
COULD ACCRETE ON VESSELS THROUGH THE FIRST WEEK OF JANUARY. THERE IS
POTENTIAL FOR MODERATE FREEZING SPRAY LATE THURSDAY NIGHT INTO EARLY
FRIDAY, THEREFORE A FREEZING SPRAY ADVISORY HAS BEEN ISSUED FOR THE
WATERS OFF OF CAPE ANN, BUZZARDS BAY, VINEYARD SOUND, AND NANTUCKET
SOUND.
THREAT FOR FREEZING SPRAY CONTINUES THIS WEEKEND, WITH A LOWER SEA
STATE THE THREAT SHOULD BE MINIMAL. HOWEVER, WE DID WANT TO GIVE IT
AT LEAST A MENTION, SINCE THE RISK FOR LIGHT VESSEL ICING DUE TO A
PROLONGED PERIOD GIVEN THE SPELL OF COLDER TEMPERATURES.
KEY MESSAGE 3...COLD BUT DRY THROUGH EARLY NEXT WEEK. INCREASING
CHANCE FOR SNOW SHOWERS ON SUNDAY.
SIGNIFICANT -NAO BLOCK SETS UP ALLOWING FOR A COLD BUT DRY PERIOD OF
WEATHER FROM THE END OF THIS WEEK THROUGH THE START OF THE NEXT
WEEK. WAVE OF LOW PRESSURE APPROACHES FROM THE S ON SUNDAY BUT
IMPACTS, IF ANY, ARE UNCERTAIN AT THIS TIME.
HIGH PRESSURE TAKES CONTROL OF OUR WEATHER TO CLOSE OUT THE WEEK
WITH COLD AND DRY CONDITIONS DEVELOPING. EXPECTING WELL BELOW
AVERAGE TEMPS WITH 925 MB TEMPERATURES BETWEEN -10C AND -15C
TRANSLATING TO SFC TEMPS THE MID 20S TO LOWER 30S. OVERNIGHT LOWS
ARE LIKELY TO BE SLIGHTLY MORE VARIABLE, IN THE MID TEENS THROUGH
THE FIRST HALF OF THIS WEEKEND, THEN DROPPING TO SINGLE DIGITS TO
LOWER TEENS BY SUNDAY NIGHT.
BEYOND THE SUSTAINED COLD, THERE IS SOME UNCERTAINTY IN THE OVERALL
PLACEMENT/TRACK OF AN AREA OF LOW PRESSURE LATER SUNDAY INTO SUNDAY
NIGHT. GENERAL THEME AMONGST GUIDANCE IS FOR A DEEP TROUGH TO DIG
ACROSS THE EASTERN CONUS WITH TWO EMBEDDED DISTURBANCES. GUIDANCE
SHOWS A POTENT NORTHERN STREAM DISTURBANCE AND A WEAKER, MORE
DIFFUSE DISTURBANCE ALONG THE SOUTHERN JET. GENERAL CONSENSUS
AMONGST OPERATIONAL AND ENSEMBLE GUIDANCE IS TO KEEP THESE FEATURES
SEPARATE WITH A WEAKER AND MORE SUPPRESSED LOW. THE 12Z SUITE HAS
SHOWN A BIT MORE AMPLIFICATION WITH THE CHANCE FOR SLIGHTLY FASTER
INTENSIFICATION BUT EVEN IN THESE RUNS, ANY SNOWFALL COMES PURELY
FROM THE NORTHERN STREAM SHORTWAVE WITH MINIMAL PHASING. IN SHORT,
WHILE LIGHT SNOW IS POSSIBLE, UPPER LEVEL CONFLUENT FLOW WILL LIKELY
SUPPRESS THE BULK OF THE PRECIPITATION WELL OFFSHORE.
AVIATION /00Z THURSDAY THROUGH MONDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
00Z TAF UPDATE...
TONIGHT INTO THURSDAY MORNING...HIGH CONFIDENCE.
VFR INTO THIS EVENING. A STEADY SHIELD OF SNOW SHOULD OVERSPREAD
THE REGION FROM WEST TO EAST IN THE 03Z TO 06Z TIME FRAME. THIS
WILL RESULT IN IFR TO BRIEFLY LIFR CONDITIONS DEVELOPING. PTYPE
SHOULD BE ALL SNOW EXCEPT FOR ACK WHERE A PERIOD OF RAIN OR
RAIN AND SNOW MIXED WILL OCCUR. STEADY SHIELD OF SNOW DEPARTS BY
10Z/11Z...BUT LINGERS A FEW HOURS LONGER NEAR THE CAPE AND
ISLANDS. IN ADDITION...A COLD FRONT MAY TRIGGER BRIEF SCATTERED
SNOW SHOWERS AND PERHAPS A LOCALIZED SNOW SQUALL OR TWO BETWEEN
10Z AND 15Z. TOTAL SNOW ACCUMULATIONS OF 1 TO 4 INCHES WITH THE
HIGHER AMOUNTS NEAR THE SOUTH COAST AND WESTERN HILLS OF
MA/CT/RI. SW WINDS 5-12 KNOTS TONIGHT SHIFTING TO THE WNW WITH
GUSTS OF 25-35 KNOTS DEVELOPING THURSDAY MORNING BEHIND THE
COLD FRONT.
THURSDAY AFTERNOON AND NIGHT...HIGH CONFIDENCE.
VFR CONDITIONS. WNW WIND GUSTS OF 25 TO 35 KNOTS THU AFTERNOON
GRADUALLY DIMINISH THU NIGHT AND BECOME MORE WESTERLY.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. SNOW ARRIVES AFTER
05Z/06Z AND CONTINUES UNTIL ABOUT 10Z/11Z. A BRIEF ROUND OF
SCATTERED SNOW SHOWERS AND PERHAPS A LOCALIZED SNOW SQUALL WILL
THEN BE POSSIBLE WITH THE COLD FRONTAL PASSAGE THROUGH ABOUT
15Z.
KBDL TERMINAL...HIGH CONFIDENCE.
HIGH CONFIDENCE IN TAF. SNOW ARRIVES AFTER 04Z/05Z AND
CONTINUES UNTIL ABOUT 08Z/09Z. A BRIEF ROUND OF SCATTERED SNOW
SHOWERS AND PERHAPS A LOCALIZED SNOW SQUALL WILL THEN BE
POSSIBLE WITH THE COLD FRONTAL PASSAGE THROUGH ABOUT 13Z/14Z.
OUTLOOK /FRIDAY THROUGH MONDAY/...
FRIDAY: VFR. BREEZY. SLIGHT CHANCE FZRA.
FRIDAY NIGHT THROUGH SATURDAY: VFR. BREEZY.
SATURDAY NIGHT: VFR. CHANCE SN.
SUNDAY: VFR. SLIGHT CHANCE SN.
SUNDAY NIGHT THROUGH MONDAY: VFR.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
* NORTHWEST GALE FORCE WINDS LATE TONIGHT THROUGH FRIDAY MORNING
ALONG WITH THE THREAT OF MODERATE FREEZING SPRAY FOR SOME WATERS.
THIS AFTERNOON THROUGH THURSDAY NIGHT... HIGH CONFIDENCE.
SOUTHWEST FLOW THROUGH THIS AFTERNOON AHEAD OF AN APPROACHING COLD
FRONT, THIS PRODUCES GUSTS IN THE RANGE OF 20-25 KNOTS. LATE TONIGHT
THE WIND SHIFTS TO THE NORTHWEST WITH GALE FORCE GUSTS THROUGH
THURSDAY NIGHT FOR ALL WATERS. EASING WIND BY FRIDAY MORNING.
THREAT FOR MODERATE FREEZING SPRAY FOR WATERS NORTH OF CAPE ANN TO
THE MERRIMACK RIVER, AS WELL AS BUZZARDS BAY, VINEYARD SOUND, AND
NANTUCKET SOUND BETWEEN THURSDAY EVENING AND FRIDAY MORNING.
BUILDING SEAS, OVERNIGHT ARE 3-5 FEET AND ARE INCREASING 5-9 FEET ON
THE SOUTHERN WATERS AND 4-8 FEET ON THE EASTERN WATERS.
OUTLOOK /FRIDAY THROUGH MONDAY/...
FRIDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS
UP TO 25 KT. LOCAL ROUGH SEAS. FREEZING SPRAY, SLIGHT CHANCE OF
FREEZING RAIN, SLIGHT CHANCE OF SNOW.
FRIDAY NIGHT: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH
GUSTS UP TO 25 KT. LOCAL ROUGH SEAS. FREEZING SPRAY.
SATURDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT.
SATURDAY NIGHT THROUGH SUNDAY: WINDS LESS THAN 25 KT. SLIGHT
CHANCE OF SNOW.
SUNDAY NIGHT THROUGH MONDAY: WINDS LESS THAN 25 KT.
BOX WATCHES/WARNINGS/ADVISORIES
CT...WINTER WEATHER ADVISORY UNTIL 1 PM EST THURSDAY FOR CTZ003-004.
MA...WINTER WEATHER ADVISORY UNTIL 1 PM EST THURSDAY FOR MAZ002-004-
008-012-013-016>023-026.
RI...WINTER WEATHER ADVISORY UNTIL 1 PM EST THURSDAY FOR RIZ001>007.
MARINE...GALE WARNING FROM 7 AM THURSDAY TO 4 AM EST FRIDAY FOR
ANZ230>237-251.
FREEZING SPRAY ADVISORY FROM 10 PM THURSDAY TO 1 PM EST FRIDAY
FOR ANZ232>234-250-251.
GALE WARNING FROM 7 AM THURSDAY TO 7 AM EST FRIDAY FOR ANZ250-
254-255.
GALE WARNING FROM 4 AM THURSDAY TO 7 AM EST FRIDAY FOR ANZ256.
DISCUSSION...DOOLEY/FT
AVIATION...MCMINN
MARINE...DOOLEY/FT
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