433
FXUS61 KBOX 240516
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
116 AM EDT MON MAR 24 2025
SYNOPSIS
INCREASING CLOUD COVER TONIGHT AS A FRONTAL SYSTEM SPREADS A
ROUND OF INTERIOR SNOW TO WINTRY MIX INTO MONDAY MORNING, WITH
PLAIN RAIN EXPECTED FOR THE COASTAL PLAIN. A MINOR ACCUMULATION
OF SNOW AND SLEET IS EXPECTED WITH VERY LIMITED IMPACTS MONDAY
MORNING BEFORE TRANSITIONING OVER TO PLAIN RAIN IN INTERIOR
SOUTHERN NEW ENGLAND. DRYING OUT FOR TUESDAY, BUT THERE IS
POTENTIAL FOR ANOTHER ROUND OF SHOWERS MID-WEEK AS A SYSTEM
TRACKS TO THE SOUTHEAST OF NEW ENGLAND. THURSDAY TRENDS DRIER
WITH TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL. A WEAK SYSTEM
BRINGS CHANCES FOR SCATTERED SHOWERS THURSDAY NIGHT INTO EARLY
FRIDAY.
NEAR TERM /UNTIL 6 AM THIS MORNING/
KEY MESSAGES:
* DECREASING NORTHWEST WIND GUSTS BY SUNDOWN.
* INCREASING CLOUD COVER OVERNIGHT, WITH LOWS UPPER 20S TO MID
30S BEFORE SLOWLY RISING INTO THE PRE-DAWN HOURS.
DETAILS:
STILL ARE DEALING WITH SOME NORTHWEST GUSTINESS OUT THERE THIS
AFTERNOON, BUT THE MAGNITUDES HAVE BEEN COMING DOWN AND THAT
WILL CONTINUE TO BE THE CASE AS WE WORK TOWARDS SUNSET. RATHER
CHILLY DAY WITH CURRENT TEMPS UPPER 30S TO MID 40S COMBINED WITH
LOW RHS (DOWN TO 15% IN SOME AREAS, 20-30% COMMON). VISIBLE
SATELLITE SHOWS THE LEADING EDGE OF AN INCREASING HIGH CLOUD
CANOPY ADVANCING INTO THE LOWER HUDSON VALLEY AND CATSKILLS IN
NEW YORK. THIS IS ASSOCIATED WITH A FRONTAL SYSTEM THAT WILL BE
SETTING ITS SIGHTS ON SOUTHERN NEW ENGLAND BY EARLY MONDAY
MORNING.
SO FOR TONIGHT EXPECT DECREASING NORTHWEST WINDS AND BECOMING
LIGHT/VARIABLE DURING THE MID-EVENING HOURS. AS LOW PRESSURE
BEGINS TO APPROACH, EXPECT WINDS TO BECOME SE AROUND MIDNIGHT
AND THAT WILL ALLOW FOR SLOW BUT STEADY SURFACE TEMPERATURE
WARMING NEAR THE COASTLINES. SOME RADIATIONAL COOLING IN
INTERIOR SOUTHERN NEW ENGLAND SHOULD ALLOW FOR LOWS IN THE MID
TO UPPER 20S FOR MOST OF THE INTERIOR PRIOR TO PRECIPITATION
BREAKING OUT AFTER ~3-5 AM, WHILE LOWS ELSEWHERE IN THE COASTAL
PLAIN AND CITIES REACHING INTO THE 30-34F RANGE WITH SLOWLY
RISING TEMPS AS SE WINDS BRING A SOMEWHAT WARMER MARITIME AIR
COMPONENT.
SHORT TERM /6 AM THIS MORNING THROUGH 6 AM TUESDAY/
KEY MESSAGES...
* INTERIOR SNOW TO WINTRY MIX WITH MINOR SNOW ACCUMULATION
BEFORE CHANGING TO RAIN. OTHER THAN A VERY BRIEF PERIOD OF WET
SNOWFLAKES MONDAY MORNING, MOST OF THE COASTAL PLAIN SEES
PREDOMINANTLY RAIN.
* GRAY/RAW MONDAY FOR MUCH OF SOUTHERN NEW ENGLAND WITH HIGHS
UPPER 30S TO LOW 40S.
SHIELD OF STEADY PRECIPITATION THEN BEGINS TO MOVE IN DURING THE
PRE-DAWN TO MID-MONDAY MORNING HOURS FROM WEST TO EAST. THE MAIN
CHANGE IN TERMS OF FORECAST GUIDANCE TRENDS IS FOR A SLOWER
ARRIVAL OF PRECIPITATION, PERHAPS A CONSEQUENCE OF THE VERY DRY
AIR CURRENTLY IN PLACE OVER SOUTHERN NEW ENGLAND. ALTHOUGH
SURFACE TEMPS MAY COOL OFF WITH INITIAL PRECIP ONSET THROUGH
WET-BULB COOLING OF INITIALLY DRIER AIR, WHICH WILL HELP
SUSTAIN SURFACE SUB- FREEZING AIR IN INTERIOR SOUTHERN NEW
ENGLAND FOR A WINTRY MIX OF SNOW AND SLEET (SOME FZRA IN THE
HIGHEST ELEVATIONS), THIS WET-BULB COOLING EFFECT NEAR THE
BOSTON- PROVIDENCE I-95 CORRIDOR AND COASTAL PLAIN SHOULD BE
OFFSET BY SEVERAL HOURS OF MODIFYING/SLOWLY WARMING TEMPS IN THE
FACE OF INCREASED SE SURFACE FLOW.
SO FOR THE COASTAL PLAIN, OTHER THAN A SHORT-LIVED PERIOD OF
WET SNOWFLAKES DURING THE MONDAY MORNING COMMUTE, THE MAJORITY
OF THE PRECIPITATION ASSOCIATED WITH THIS SYSTEM WILL FALL IN
THE FORM OF RAIN. IF ANY INITIAL PRECIP FALLS AS SNOW FOR THESE
AREAS (ROUGHLY INSIDE OF I-495 AND I-95), IT'S LIKELY THAT ANY
COATINGS WHICH DEVELOP WILL BE QUICKLY WASHED AWAY BY RAINS.
STORM TOTAL RAINFALL FOR THE COASTAL PLAIN AROUND A HALF TO TWO
THIRDS OF AN INCH.
FURTHER INLAND, INCLUDING THE AREA NORTH AND WEST OF I-95, THIS
IS WHERE A PERIOD OF MORE SUSTAINED WINTRY WEATHER TAKES PLACE,
ALTHOUGH THIS AREA WILL ALSO GRADUALLY SEE A SOUTH-TO-NORTH
TRANSITION OVER TO PLAIN RAIN WITH WARMING SURFACE TEMPS. MODEL
SOUNDINGS SHOW A WEAK WARM NOSE WITH MAX TEMPS IN THAT WARM
NOSE AROUND 1-1.5 C WITH A SHALLOW LAYER OF SUB-FREEZING AIR
IMMEDIATELY BENEATH IT TO THE SURFACE. THIS SUGGESTS A LIGHT
WINTRY MIX OF SNOW WITH REFROZEN SLEET PELLETS AT ONSET, WHICH
THEN GRADUALLY CHANGES OVER TO PLAIN RAIN DURING THE MONDAY LATE
MORNING TO AFTERNOON PERIOD. THERE COULD BE SOME REALLY MINOR
ICE ACCRETION IN THE HIGHEST ELEVATIONS IN THE BERKSHIRES MONDAY
MORNING BUT FORECAST AMOUNTS AND EXPECTED VERY LIMITED IMPACT
(FALLING ONTO A LIGHT SNOWPACK) TO PRECLUDE THE NEED FOR WINTER
WEATHER ADVISORIES. FORECAST SNOW/SLEET ACCUMULATIONS OF UP TO A
COUPLE INCHES BEFORE THE TRANSITION OVER TO RAIN, AND THIS RAIN
WILL HELP WASH THIS SLUSHY MINOR ACCUMULATION AWAY HERE AS
WELL.
MONDAY IS LIKELY GOING TO BE A PRETTY RAW DAY, WITH ABUNDANT
CLOUD COVER AND RAIN, WITH PRECIPITATION COMING TO AN END FROM
WEST TO EAST BY THE LATE AFTERNOON TO SUNDOWN PERIOD. TEMPS MAY
ONLY RISE INTO THE UPPER 30S/NEAR 40 NORTHERN MA, TO THE MID
40S ELSEWHERE. FOR MONDAY EVENING, ALTHOUGH WE DO CLEAR OUT IN
TERMS OF PRECIPITATION, A DRYSLOT TRAPPING SHALLOW MOISTURE
COULD ALLOW FOR PARTLY TO MOSTLY CLOUDY SKIES BEFORE IMPROVING
LATE MONDAY NIGHT/EARLY TUESDAY. LOWS IN THE MID 30S TO NEAR 40.
LONG TERM /TUESDAY THROUGH SUNDAY/
KEY MESSAGES:
* POTENTIAL FOR SYSTEM TO BRING A ROUND OF SHOWERS WEDNESDAY.
* SCATTERED SHOWERS POSSIBLE THURSDAY NIGHT INTO EARLY FRIDAY.
* MORE UNSETTLED WEATHER POSSIBLE FOR THE WEEKEND.
TUESDAY:
DRY CONDITIONS PREVAIL TUESDAY WITH BREEZY WESTERLY WINDS. DESPITE
COOLER 850MB TEMPERATURES, DOWNSLOPING AND PERIODS OF SUNSHINE WILL
BRING HIGH TEMPERATURES IN THE UPPER 40S TO MID 50S ACROSS SOUTHERN
NEW ENGLAND.
WEDNESDAY - FRIDAY:
AN UPPER LEVEL TROUGH REMAINS ANCHORED ACROSS THE NORTHEAST WITH AN
EMBEDDED SHORTWAVE TROUGH MOVING THROUGH THE FLOW WEDNESDAY. THIS
WILL TRACK A SYSTEM NEAR THE REGION BRING OUR NEXT SHOT AT SEEING
PRECIPITATION. DETAILS STILL NEED TO BE IRONED OUT ESPECIALLY WITH
THE TRACK WHICH WILL IMPACT QPF AND PRECIPITATION CHANCES. ENSEMBLE
GUIDANCE SHOWS DECENT AGREEMENT AMONG MEMBERS WITH THE SURFACE LOW
TRACKING SOUTHEAST OF SOUTHERN NEW ENGLAND. PROBABILITIES FOR >0.10"
OF QPF ARE HIGHEST ACROSS THE CAPE AND ISLANDS WHERE THEY RANGE FROM
50 TO 70 PERCENT ACROSS VARIOUS ENSEMBLE GUIDANCE. RAIN AMOUNTS WILL
DEPEND ON HOW THE SURFACE LOW TRACKS, BUT OVERALL THIS STILL
LOOKS LIKE LIGHTER RAIN EVENT ON MOST GUIDANCE.
THURSDAY WILL FEATURE A BRIEF DRY PERIOD WITH A TRANSIENT AREA OF
HIGH PRESSURE BUILDING IN FROM THE SOUTH. DESPITE THIS, HIGH
TEMPERATURES WILL REMAIN SLIGHTLY BELOW NORMAL IN THE MID 40S TO
UPPER 40S. A WEAK EMBEDDED SHORTWAVE WITHIN TROUGH ALOFT MAY BRING
ANOTHER ROUND OF LOW COVERAGE/SCATTERED SHOWERS LATER THURSDAY INTO
EARLY FRIDAY. THE HIGHER ELEVATIONS OF THE INTERIOR MAY SEE A FEW
SNOW SHOWERS. THERE IS A LOW CHANCE FOR LIGHT SNOW ACCUMULATION FOR
THE HIGH POINTS OF THE BERKSHIRES OVERNIGHT. BREEZY CONDITIONS
FRIDAY WITH HIGHS IN THE UPPER 40S TO LOW 50S IN MOST SPOTS.
WEEKEND:
ENSEMBLES SUGGEST THAT THE PARADE OF SHORTWAVES CONTINUE INTO NEXT
WEEKEND. THERE IS THE POTENTIAL FOR YET ANOTHER AREA OF LOW PRESSURE
LATER SATURDAY INTO SUNDAY. ENSEMBLES EVEN SUGGEST A PERIOD OF
WINTRY PRECIPITATION AT THE ONSET, BUT DETAILS ARE FAR FROM CERTAIN
AT THIS TIME.
AVIATION /05Z MONDAY THROUGH FRIDAY/
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
06Z TAF UPDATE:
THROUGH 12Z: HIGH CONFIDENCE IN TRENDS, THOUGH SOME UNCERTAINTY
ON TIMING OF PRECIPITATION.
VFR TO START THEN DECREASING TO IFR LATE MORNING AND AFTERNOON
IN RA. ARRIVAL OF PRECIP AND MVFR CEILINGS/VISBYS AROUND
08-12Z, WHICH WOULD START AS A PERIOD OF LIGHT SNOW MIXED WITH
PL MIXING IN FOR INTERIOR TERMINALS. THERE IS A LOW PROBABILITY
OF A BRIEF PERIOD OF FZRA AT BAF DURING THE TRANSITION FROM SN
TO RA. LITTLE ACCUM OF SN OR FZRA IF ANY BEFORE 12Z. SN/SNPL CHANGING
TO RA FOR THE INTERIOR AIRPORTS BETWEEN 14-17Z. ELSEWHERE,
OTHER THAN A BRIEF PERIOD OF WET SNOW AT ONSET FOR PVD, BED AND
BOS AROUND 13-14Z, VAST MAJORITY OF PRECIP IS RA. RA FOR THE
CAPE/ISLANDS. PRECIP ENDS FROM WEST TO EAST 20-23Z, BUT CEILINGS
MAY STILL BE LOW AS DRYSLOT MOVES IN ALOFT AND TRAPS CLOUD
COVER AROUND. SE TO S WINDS 10 TO 15 KT WITH GUSTS NEAR THE
SOUTH COAST AROUND 25 KT. SOME LOW LEVEL SHEAR POSSIBLE FOR PVD
AND THE CAPE AIRPORTS BETWEEN 18 AND 20Z. LOW LEVEL SHEAR MAY
CONTINUE THRU 23Z ACROSS THE CAPE.
TONIGHT: HIGH CONFIDENCE.
INITIAL MVFR-IFR CEILINGS SLOWLY IMPROVE TO MVFR, MAINLY AFTER
MIDNIGHT. SW WINDS DECREASING TO AROUND 5 KT OR LESS.
TUESDAY: HIGH CONFIDENCE.
VFR. WSW WINDS 10-15 KTS GUSTING 15 TO 20 KTS.
BOS TAF...MODERATE CONFIDENCE IN TAF. SMALL PROBABILITY OF SN
MIXING IN AT THE ONSET OF PRECIPITATION.
BDL TAF...MODERATE CONFIDENCE IN TAF. PRECIPITATION MAY BEGIN
AS LATE AS 13Z.
OUTLOOK /TUESDAY THROUGH FRIDAY/...
TUESDAY: VFR. BREEZY.
TUESDAY NIGHT: VFR. SLIGHT CHANCE RA.
WEDNESDAY: VFR. CHANCE RA.
WEDNESDAY NIGHT: VFR.
THURSDAY THROUGH FRIDAY: VFR. BREEZY.
MARINE
FORECASTER CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
415 PM UPDATE:
OVERALL HIGH CONFIDENCE.
SMALL CRAFT ADVISORIES ISSUED FOR MONDAY INTO MONDAY NIGHT.
FOR TONIGHT, DECREASING NW WIND GUSTS TO BECOME LIGHT/VARIABLE,
THEN WINDS BECOME E-SE AROUND 5-10 KT. SE WINDS THEN INCREASE TO
AROUND 15-25 KT WITH GUSTS TO 30 KT MONDAY MORNING WHICH
CONTINUE INTO MONDAY AFTERNOON. WINDS BECOMING S AND DECREASING
TO AROUND 10-15 KT MONDAY NIGHT. SEAS DECREASE TO AROUND 3-4 FT
ALL WATERS TONIGHT, THEN INCREASE TOWARD MONDAY MORNING TO
AROUND 4-8 FT, HIGHEST ON THE SOUTHERN OFFSHORE WATERS. RAIN
DEVELOPS MONDAY MORNING AND CONTINUES INTO EARLY MONDAY NIGHT,
WITH VISBYS DECREASING TO 2-4 MILES.
OUTLOOK /TUESDAY THROUGH FRIDAY/...
TUESDAY: WINDS LESS THAN 25 KT. LOCAL ROUGH SEAS.
TUESDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT. SLIGHT CHANCE OF RAIN.
WEDNESDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING
5 FT. CHANCE OF RAIN.
WEDNESDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS
APPROACHING 5 FT. SLIGHT CHANCE OF RAIN.
THURSDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT.
THURSDAY NIGHT: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH
GUSTS UP TO 25 KT. AREAS OF SEAS APPROACHING 5 FT.
FRIDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS
UP TO 25 KT. SEAS UP TO 5 FT.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR ANZ230-236.
SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 2 AM EDT
TUESDAY FOR ANZ231>235-237-251.
SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 5 AM EDT
TUESDAY FOR ANZ250.
SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 8 PM EDT
TUESDAY FOR ANZ254>256.
SYNOPSIS...LOCONTO/FT
NEAR TERM...LOCONTO
SHORT TERM...LOCONTO
LONG TERM...FT
AVIATION...BW/FT
MARINE...LOCONTO/FT
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