024
FXUS61 KBOX 071729
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
1229 PM EST SAT FEB 7 2026
WHAT HAS CHANGED
THE WINTER STORM WATCH FOR ESSEX COUNTY HAS BEEN UPGRADED TO A
WINTER STORM WARNING. WINTER WEATHER ADVISORIES CONTINUE FOR THE
REMAINDER OF EASTERN MA INTO THE WORCESTER HILLS AND DOWN INTO RI.
KEY MESSAGES
- 3-6 INCHES OF SNOW EXPECTED ACROSS CENTRAL AND EASTERN MA INTO
RI, WITH LOCALIZED BANDS OF HEAVIER SNOW, POSSIBLY UP TO 8
INCHES IN ESSEX COUNTY. LESS SNOW WESTWARD INTO CT AND WESTERN
MA.
- DANGEROUS COLD TONIGHT INTO SUNDAY. GUSTY WINDS SUPPORTING
WIND CHILLS THAT FALL 10 TO 30 DEGREES BELOW ZERO. HIGH
CONFIDENCE IN HAZARDOUS FREEZING SPRAY OVER THE WATERS.
DISCUSSION
KEY MESSAGE 1...3-6 INCHES OF SNOW EXPECTED ACROSS CENTRAL AND
EASTERN MA INTO RI, WITH LOCALIZED BANDS OF HEAVIER SNOW,
POSSIBLY UP TO 8 INCHES IN ESSEX COUNTY. LESS SNOW WESTWARD
INTO CT AND WESTERN MA.
VERY DYNAMIC SYSTEM MOVING THROUGH TODAY AS DEEP AMPLIFYING
TROUGH BECOMES NEGATIVELY TILTED AND CLOSES OFF SOUTH OF NEW
ENG WITH -38C POCKET AT 500 MB. STRONG HEIGHT FALLS WILL YIELD
CYCLOGENESIS WELL OFFSHORE BUT DEEP UPSTREAM MID LEVEL TROUGH
AXIS WILL RESULT IN INVERTED/NORLUN TROUGH EXTENDING NW FROM THE
OFFSHORE LOW INTO SNE SAT. MEANWHILE, ARCTIC FRONT WILL BE
MOVING THROUGH SNE AND EVENTUALLY MERGING WITH INVERTED TROUGH.
INCREASING FORCING FOR ASCENT COMBINED WITH DEEP SATURATED LAYER
THROUGH THE MID LEVELS HAS RESULTED IN SNOW DEVELOPING ACROSS
SNE EARLY THIS MORNING AND THIS WILL CONTINUE THROUGH THE DAY,
ALTHOUGH THE FOCUS WILL SHIFT TO CENTRAL/E MA AND RI LATE
MORNING THROUGH THE AFTERNOON. WE MAY SEE SOME BRIEF ENHANCEMENT
TO THE SNOW ALONG THE ARCTIC FRONT AFTER 12Z IN WESTERN NEW
ENG, THEN SNOW SHOULD TAPER OFF HERE BY MID-LATE MORNING BEHIND
THE FRONT. OTHERWISE, WE WILL HAVE TO WATCH FOR SOME HEAVIER
BANDS OF SNOW DEVELOPING ACROSS RI AND POSSIBLY INTO CENTRAL MA
THIS MORNING ALONG AN AREA OF LOW LEVEL CONVERGENCE. THEN VERY
INTERESTING AND COMPLEX EVOLUTION LATE MORNING THROUGH THE
AFTERNOON AS HI-RES GUIDANCE INDICATING SNOW BANDS MOVING
WESTWARD ACROSS NE MA WITHIN CONVERGENT NE FLOW THEN ROTATING
SOUTHWARD ACROSS EASTERN MA THROUGH THE AFTERNOON AS IT MERGES
WITH INVERTED TROUGH. THESE INVERTED TROUGHS ARE NOTORIOUS FOR
LOCALIZED HEAVY SNOW BANDS AND IT IS LIKELY THAT THIS WILL BE
THE CASE TODAY AS THERE ARE STRONG MODEL SIGNALS FOR POTENTIALLY
HEAVY SNOWFALL RATES. STEEP 0-3KM LAPSE RATES COMBINED WITH
STRONG LOW LEVEL CONVERGENCE/FRONTOGENESIS AND MARGINAL LOW
LEVEL CAPE ARE STRONG INDICATORS OF HEAVY SNOWFALL RATES. THE
SNOW SQUALL PARAMETER REALLY LIGHTS UP MID-LATE AFTERNOON ACROSS
EASTERN AND SE MA WHERE ARCTIC FRONT MERGES WITH INVERTED
TROUGH ENHANCING LOW LEVEL CONVERGENCE. GFS AND NAM SOUNDINGS
ALSO SHOWING STRONG OMEGA, IN SOME CASES 20-30 UB/S, EXTENDING
THROUGH THE DGZ. THIS WILL LIKELY RESULT IN A 2-4 HOUR PERIOD OF
HEAVY SNOW DURING THE AFTERNOON ACROSS PORTIONS OF EASTERN MA
WITH LOCALIZED SNOWFALL RATES OF 1-2"/HR.
FORECASTING THE EXACT PLACEMENT OF THESE MESOSCALE FEATURES
WITH THESE INVERTED TROUGH EVENTS AND WHERE HEAVY BANDS WILL SET
UP IS QUITE CHALLENGING AND OFTEN OFFERS LOW PREDICTABILITY
UNTIL IT BEGINS TO DEVELOP. ADDITIONALLY THERE ALSO CAN BE AREAS
OF SUBSIDENCE BETWEEN BANDS LEADING TO HIGH VARIABILITY IN
SNOWFALL AMOUNTS OVER SHORT DISTANCES.
BECAUSE MESOSCALE FACTORS WILL BE A BIG FACTOR IN SNOWFALL WE
LEANED ON HI-RES GUIDANCE FOR SNOW ACCUM FORECAST. A LOT OF THE
GUIDANCE IS SUGGESTING A MAX QPF AXIS ACROSS ESSEX COUNTY WHERE
THERE IS LOW LEVEL CONVERGENCE FROM LAND SEA INTERFACE, WHILE A
SECONDARY MAX IS POSSIBLE IN RI FROM LOW LEVEL CONVERGENCE
WHICH SETS UP THIS MORNING. OVERALL, WE ARE LOOKING AT ACCUMS OF
3-6 INCHES ACROSS MUCH OF THE ADVISORY AREA FROM CENTRAL AND
EASTERN MA DOWN ACROSS RI, WITH LOCALLY UP TO 8 INCHES ACROSS
ESSEX COUNTY WHERE THE WINTER STORM WATCH WILL BE UPGRADED TO A
WARNING. THERE IS A LOW RISK THAT LOCALIZED AMOUNTS COULD EXCEED
8 INCHES IN ESSEX COUNTY. WE DO HAVE SOME CONCERN THAT SOME OF
THE HEAVIER SNOW COULD EXTEND DOWN THE COAST INTO BOSTON AND
PLYMOUTH COUNTY WHERE SOME 6+ INCH AMOUNTS ARE POSSIBLE BUT
CONFIDENCE IN EXCEEDING 6 INCHES HERE IS LOW. AND CAN'T RULE OUT
LOCALIZED 6 INCH AMOUNTS IN RI IF THE HEAVIER SNOW BANDS HERE
COME TO FRUITION. FURTHER WEST AMOUNTS WILL DROP OFF WITH
GENERALLY 1-3 INCHES ACROSS WESTERN MA INTO THE CT VALLEY. WE
WANT TO EMPHASIZE THAT FORECAST CONFIDENCE IS MODERATE AS THE
PLACEMENT OF THESE HEAVY SNOW BANDS CAN SHIFT.
THE SNOW IN RI AND EASTERN MA SHOULD TAPER OFF AND END BETWEEN 4-7
PM. THEN OCEAN EFFECT SNOW SHOWERS WILL LINGER ON CAPE COD AND
NANTUCKET THROUGH THE EVENING WITH ADDITIONAL ACCUM BRINGING TOTAL
ACCUMS TO 2-4 INCHES HERE.
KEY MESSAGE 2...DANGEROUS COLD FOR SATURDAY NIGHT INTO SUNDAY. GUSTY
WINDS SUPPORTING WIND CHILLS THAT FALL 10 TO 30 DEGREES BELOW ZERO.
HIGH CONFIDENCE IN HAZARDOUS FREEZING SPRAY OVER THE WATERS.
CONFIDENCE REMAINS HIGH FOR THE DANGEROUSLY COLD CONDITIONS THAT
WILL FOLLOW THE ARCTIC FRONTAL PASSAGE. THE FRONT MOVES THROUGH THE
REGION DURING THE AFTERNOON HOURS SATURDAY, AND AN ARCTIC AIRMASS
FOLLOWS BEHIND IT. LOWER LEVEL TEMPERATURES AROUND -10C (AT 925 MB)
FALL TO AROUND -20C AND LOWER ACROSS THE REGION, PARTICULARLY THE
INTERIOR BY SUNDAY MORNING. SOME GUIDANCE HAS 925 MB TEMPERATURES
OVER EASTERN MA BETWEEN -15C AND -12C, BUT THE BOTTOM LINE IS THAT
THE ENVIRONMENT WILL BE HIGHLY SUPPORTIVE OF DANGEROUSLY COLD
TEMPERATURES. WIND CHILL VALUES WILL BE THE GREATEST CONCERN. A 925
MB JET DEVELOPS HEADING INTO SATURDAY NIGHT/SUNDAY MORNING WITH WIND
SPEEDS AROUND 40 TO 45 KNOTS. FORECAST SOUNDINGS CONTINUE TO
INDICATE THAT THESES WINDS ARE ALSO AT THE TOP OF THE MIXED LAYER,
SO WITH THESE WINDS MIXING DOWN TO THE SURFACE POST-FRONT, GUSTS
BETWEEN 30-40 MPH ARE HIGHLY PROBABLE THROUGH THE NIGHT. THIS WILL
BRING WIND CHILLS DOWN TO 30 BELOW 0F IN PARTS OF THE BERKSHIRES AS
AIR TEMPERATURES ON THEIR OWN ARE ALREADY EXPECTED TO BE IN THE
NEGATIVES. THE REST OF THE INTERIOR COULD SEE WIND CHILL VALUES DOWN
TO 25 BELOW 0F AND EASTERN MA CAN EXPECT WIND CHILLS GENERALLY
AROUND 10 BELOW 0F, WITH THE OUTER CAPE AND ISLANDS THE WARMEST IN
THE POSITIVE SINGLE DIGITS.
HEAVY FREEZING SPRAY IS ANOTHER MAJOR CONCERN THROUGH MONDAY MORNING
WITH THESE VERY COLD TEMPERATURES COMBINED WITH STRONG, GUSTY WINDS.
ICE ACCRETION RATES BETWEEN 0.5-1" PER HOUR ARE POSSIBLE WITHIN THE
HEAVY FREEZING SPRAY WARNING AREA, WHICH INCLUDES ALL WATERS EXCEPT
BOSTON HARBOR. THOUGH, LIGHT FREEZING SPRAY IN BOSTON HARBOR IS NOT
OUT OF THE REALM OF POSSIBILITY; ICE ACCRETION RATES ARE NOT EXPECTED
TO GET THAT HIGH THERE.
THE DISTANT OFFSHORE LOW TO OUR SOUTHEAST CONTINUES ITS WAY OUT TO
SEA FOR THE START OF THE WEEK AND HIGH PRESSURE OVER THE EASTERN
GREAT LAKES BUILDS IN. GUSTY WINDS FROM 20 TO 30 MPH PERSIST THROUGH
SUNDAY BEFORE THE PRESSURE GRADIENT STARTS TO WEAKEN, AND HIGH
PRESSURE TAKES CONTROL OF THE PATTERN OVER SOUTHERN NEW ENGLAND
MONDAY INTO TUESDAY. DRY CONDITIONS MAKE A RETURN WITH CONTINUED
BELOW-NORMAL TEMPERATURES, THOUGH WEDNESDAY COULD SEE HIGHS IN THE
MID 30S. THESE ARE STILL BELOW NORMAL, BUT MAY FEEL MUCH WARMER THAN
WHAT WE'VE DEALT WITH LATELY.
WE ARE CONTINUING TO MONITOR ANOTHER POSSIBLE SYSTEM THAT COULD
IMPACT SOUTHERN NEW ENGLAND SOMETIME MIDWEEK. LATEST GUIDANCE STILL
DOESN'T HAVE A SOLID GRASP ON TRACK OR EXACT TIMING, WHICH IS NOT
EXPECTED THIS FAR OUT. BUT GENERALLY, 925 MB TEMPERATURES COULD
CLIMB TO AROUND -5C AND EVEN 0C BY WEDNESDAY MORNING. A LOW FROM THE
NW MAY CROSS OVER THE NORTHEAST THAT COULD LEAD TO SHOWERS ACROSS
SOUTHERN NEW ENGLAND. BUT AGAIN, IT IS TOO FAR OUT TO KNOW FOR
CERTAIN AND MUCH CAN AND WILL CHANGE BETWEEN NOW AND THEN.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
18Z TAF UPDATE...
THIS AFTERNOON...MODERATE CONFIDENCE.
MVFR-IFR CONDITIONS IN AREAS OF SNOW WITH LOCALIZED HEAVIER SNOW
BANDS AND LIFR ACROSS EASTERN MA AND RI TERMINALS. INCREASING
N-NW WINDS FROM W TO E WITH GUSTS TO 25-35 KT DEVELOPING.
TONIGHT...MODERATE CONFIDENCE IN TIMING.
MVFR IMPROVES TO VFR DURING THE EVENING, EXCEPT FOR CAPE COD AND
NANTUCKET WHERE LOWER CIGS/VSBYS LINGER IN OCEAN EFFECT SNOW
SHOWERS. NW WIND GUSTS 25-35 KT. OCCASIONAL GUSTS ON CAPE COD
AND NANTUCKET TO 40 KT POSSIBLE JUST BEFORE MIDNIGHT.
SUNDAY...HIGH CONFIDENCE.
VFR. GUSTY NW WINDS CONTINUE TO GUST 25-30 KTS IN THE MORNING,
DECREASING TO TO 18-25 KTS IN THE AFTERNOON.
OUTLOOK /SUNDAY THROUGH WEDNESDAY/...
SUNDAY: VFR. WINDY WITH LOCAL GUSTS UP TO 30 KT.
SUNDAY NIGHT THROUGH MONDAY NIGHT: VFR. BREEZY.
TUESDAY: VFR.
TUESDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. CHANCE SN.
WEDNESDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. SLIGHT CHANCE
SN.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
HEADLINES:
* GALE WARNINGS FROM SAT AFTERNOON INTO SUNDAY.
* HEAVY FREEZING SPRAY WARNINGS FOR SATURDAY AFTERNOON THROUGH
EARLY MON MORNING.
INCREASING NE WINDS ON EASTERN MA WATERS BECOMING N LATER TODAY,
WITH INCREASING N-NW WINDS ON THE SOUTH COASTAL WATERS. GUSTS
INCREASING TO 30-40 KT MID TO LATER AFTERNOON THROUGH TONIGHT BEHIND
THE ARCTIC FRONT. AREAS OF HEAVY FREEZING SPRAY WILL DEVELOP TONIGHT
INTO SUNDAY AS GUSTY GUSTY WINDS COMBINE WITH ARCTIC AIR MOVING INTO
THE REGION. HEAVY FREEZING SPRAY PRODUCES ICE ACCRETION RATES UP TO
1 INCH/HR CREATING VERY DANGEROUS CONDITIONS FOR VESSELS.
OUTLOOK /SUNDAY THROUGH WEDNESDAY/...
SUNDAY: STRONG WINDS WITH GUSTS UP TO 30 KT. ROUGH SEAS UP TO
12 FT. FREEZING SPRAY.
SUNDAY NIGHT: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH
GUSTS UP TO 25 KT. ROUGH SEAS UP TO 10 FT. FREEZING SPRAY.
MONDAY: WINDS LESS THAN 25 KT. AREAS OF ROUGH SEAS. FREEZING
SPRAY.
MONDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. FREEZING
SPRAY.
TUESDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING 5 FT.
TUESDAY NIGHT: WINDS LESS THAN 25 KT. CHANCE OF SNOW.
WEDNESDAY: WINDS LESS THAN 25 KT. CHANCE OF RAIN, CHANCE OF
SNOW.
BOX WATCHES/WARNINGS/ADVISORIES
CT...EXTREME COLD WARNING FROM 6 PM THIS EVENING TO 1 PM EST SUNDAY
FOR CTZ002>004.
MA...EXTREME COLD WARNING FROM 6 PM THIS EVENING TO 1 PM EST SUNDAY
FOR MAZ002>004-008>012.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MAZ004-
005-012>021-026.
COLD WEATHER ADVISORY FROM 6 PM THIS EVENING TO 1 PM EST
SUNDAY FOR MAZ005>007-013>023-026.
WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR MAZ006-
007.
WINTER WEATHER ADVISORY UNTIL 1 AM EST SUNDAY FOR MAZ022>024.
RI...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
RIZ001>008.
COLD WEATHER ADVISORY FROM 6 PM THIS EVENING TO 1 PM EST
SUNDAY FOR RIZ001>008.
MARINE...GALE WARNING FROM 4 PM THIS AFTERNOON TO 7 AM EST SUNDAY FOR
ANZ230-236.
FREEZING SPRAY ADVISORY FROM 4 PM THIS AFTERNOON TO 7 PM EST
SUNDAY FOR ANZ230.
GALE WARNING FROM 4 PM THIS AFTERNOON TO 1 PM EST SUNDAY FOR
ANZ231-232-250-251-254.
HEAVY FREEZING SPRAY WARNING FROM 4 PM THIS AFTERNOON TO 7 AM
EST MONDAY FOR ANZ231>237-250-251-254>256.
GALE WARNING UNTIL 10 AM EST SUNDAY FOR ANZ233>235-237.
GALE WARNING UNTIL 1 PM EST SUNDAY FOR ANZ255-256.
DISCUSSION...KJC/HRENCECIN
AVIATION...BW/KP
MARINE...KJC
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