400
FXUS61 KBOX 281124
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
724 AM EDT TUE APR 28 2026
WHAT HAS CHANGED
INCREASED RAINFALL AMOUNTS WEDNESDAY NIGHT INTO THURSDAY.
OTHERWISE, NO OTHER SIGNIFICANT CHANGES WERE MADE TO THE
FORECAST.
KEY MESSAGES
- PLEASANT WEATHER CONTINUES TODAY AND TONIGHT WITH THE WARMEST
TEMPERATURES INLAND AND ACROSS THE CT VALLEY. MUCH COOLER CONDITIONS
ALONG THE COAST WITH HIGHS IN THE UPPER 40S TO LOWER 50S.
- INCREASING CHANCE FOR SHOWERS ACROSS COASTAL AREAS WEDNESDAY.
BETTER CHANCE FOR A MORE WIDESPREAD SOAKING RAIN THURSDAY.
- UPPER LEVEL LOW KEEPS THINGS COOLER AND UNSETTLED FRIDAY INTO THE
WEEKEND.
DISCUSSION
KEY MESSAGE 1... PLEASANT WEATHER CONTINUES TODAY AND TONIGHT WITH
THE WARMEST TEMPERATURES INLAND AND ACROSS THE CT VALLEY. MUCH
COOLER CONDITIONS ALONG THE COAST WITH HIGHS IN THE UPPER 40S TO
LOWER 50S.
RIDGE OF HIGH PRESSURE CRESTS OVERHEAD THIS AFTERNOON THROUGH THE
OVERNIGHT. THIS RESULTS IN A MAINLY CLEAR DAY OUTSIDE OF A FEW MID
AND HIGH LEVEL CLOUDS AHEAD OF AN AREA OF LOW PRESSURE THAT WILL
PASS WELL TO THE NORTHWEST OF THE CWA. OF GREATER CONSEQUENCE WILL
BE A FAIRLY STIFF ONSHORE FLOW THAT WILL BE 5-10 MPH STRONGER THAN
WHAT WE SAW ON MONDAY. THE STRONGER ONSHORE FLOW WILL LIKELY HELP
KNOCK TEMPS A FEW DEGREES LOWER THAN WE'VE SEEN IN RECENT DAYS.
NONETHELESS...STILL EXPECT HIGHS TO REACH INTO THE 60S IN MOST
LOCATIONS AWAY FROM THE IMMEDIATE COAST. THE MILD SPOTS WILL AGAIN
BE THE CT VALLEY WHERE HIGH TEMPS OF 70+ SEEM LIKELY.
MEANWHILE...ONSHORE FLOW WILL HOLD HIGH TEMPS MAINLY IN THE
LOWER TO MIDDLE 50S ALONG THE IMMEDIATE COAST, CAPE AND ISLANDS.
MAINLY DRY AND COOL AGAIN TONIGHT WITH ANOTHER NIGHT OF DECENT
RADIATIONAL COOLING. THE MAGNITUDE OF COOLING WILL BE LESS THAN
PREVIOUS NIGHTS WITH A MID AND HIGH LEVEL CLOUD DECK BUILDING
OVERHEAD. LOWS WILL BE IN THE 30S IN MANY LOCATIONS WITH LOWER 40S
IN MOST AREAS. HIGH RES GUIDANCE SHOWS AREAS OF LOW STRATUS, PATCHY
SHOWERS, AND DRIZZLE MAINLY ACROSS SE MA AND THE ISLANDS LATE
TONIGHT. STILL SOMEWHAT LOW (20-35%) POPS MAINLY CONTINGENT UPON THE
ORIENTATION/LOCATION OF AN INVERTED TROUGH EXTENDING FROM A DISTANT
COASTAL LOW.
KEY MESSAGE 2...INCREASING CHANCE FOR SHOWERS ACROSS COASTAL AREAS
WEDNESDAY. BETTER CHANCE FOR A MORE WIDESPREAD SOAKING RAIN
THURSDAY.
MOST PLACES REMAIN DRY FOR WEDNESDAY AS HIGH PRESSURE WILL BE
SLOW TO MOVE OFFSHORE. AS A TROUGH APPROACHES FROM THE WEST,
PRECIPITABLE WATER (PWATS) INCREASE TO 0.5-1.0 INCHES.
THEREFORE, EXPECT CLOUDY SKIES FOR THE DAY WITH CONTINUED NE
FLOW. HIGHEST CHANCE OF SHOWERS ACROSS EASTERN MASS AND
ESPECIALLY THE ISLANDS WHERE HIGH RES GUIDANCE SHOWS THE
INVERTED TROUGH SETTING UP AND ACTING AS A SOURCE OF LIFT.
MORE BROAD SYNOPTIC-SCALE LIFT FROM AN APPROACHING SHORTWAVE BRINGS
AN INCREASING CHANCE FOR WIDESPREAD LIGHT TO PERHAPS MODERATE
RAINFALL WEDNESDAY NIGHT INTO THURSDAY MORNING. PWAT VALUES RISE TO
AROUND 1.0-1.5", SUPPORTIVE OF WIDESPREAD SHOWERS/RAIN. MODEL
GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THE IDEA OF A SECONDARY
LOW DEVELOPING OFFSHORE OF THE CAPE THURSDAY. WE ARE STILL
MONITORING THE RISK FOR COASTAL FLOODING BUT THE PROBABILITY IS
STILL QUITE LOW AT THIS POINT FOR THE EASTERN COASTAL AREAS. FOR
EXAMPLE, THE STEVEN'S INSTITUTE COASTAL FLOODING GUIDANCE DOES
INDICATE A LOW PROBABILITY (~5%) OF NEAR FLOOD/SPLASHOVER FOR EAST-
FACING BEACHES. THANKFULLY, NOT LOOKING AT A SIGNIFICANT CHANCE FOR
FRESHWATER FLOODING AS RAINFALL WILL BE QUICK TO MOVE OUT THURSDAY
AFTERNOON. THE 01Z NBM MEAN 24 HOUR QPF HAS INCREASED FROM A
WIDESPREAD 0.5-0.75" TO 0.75-1.0". THERE IS EVEN A SWATH OF MEAN
QPF >1" ACROSS NE MASSACHUSETTS.
KEY MESSAGE 3...UPPER LEVEL LOW KEEPS THINGS COOLER AND UNSETTLED
FRIDAY INTO THE WEEKEND.
WEATHER PATTERN REMAINS UNSETTLED FRIDAY THROUGH THE WEEKEND AS A
REX BLOCKS KEEPS AN UPPER LEVEL LOW ABOVE NORTHERN NEW ENGLAND. THIS
PATTERN WILL BRING A MUCH COOLER AIRMASS WITH 850MB TEMPERATURE
ANOMALIES FALLING TO 6-8C BELOW NORMAL. NON ZERO POPS CONTINUE
THROUGH THE WEEKEND UNDER A SLOW MOVING COLD POOL ALOFT (500MB TEMPS
FALLING TO -20 TO -30C). THIS WILL LEAD TO SOME INSTABILITY, SO
CAN'T RULE OUT A GRAUPEL WITHIN ANY SHOWERS. THERE ARE STILL
MODEL/ENSEMBLE MEMBERS THAT INDICATE THE POTENTIAL FOR A COASTAL
SYSTEM TO GIVE A GLANCING BLOW TO SOUTHERN NEW ENGLAND OVER THE
WEEKEND. THE TREND WITH THE 00Z ENSEMBLES HAS BEEN A SOLUTION MUCH
FURTHER TO THE EAST. THE OTHER SCENARIO IS A CLOSER TRACK WITH
RAIN/GUSTY WINDS LATER SATURDAY INTO SUNDAY TO PORTIONS OF SOUTHERN
NEW ENGLAND. AGAIN, THIS IS STILL LOW PROBABILITY SCENARIO
RIGHT NOW BEING DISPLAYED BY A SMALL PERCENTAGE OF MODEL
SOLUTIONS. THIS WILL CONTINUE TO BE MONITORED AS CONFIDENCE IN
THE UPPER PATTERN AND DETAILS INCREASES AS WE GET CLOSER.
AVIATION /12Z TUESDAY THROUGH SATURDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
12Z TAF UPDATE:
TODAY...HIGH CONFIDENCE. LOW/MOD FOR LOW CLOUDS ON
CAPE/ISLANDS.
VFR FOR MOST. A STRATUS DECK WILL LIKELY IMPACT THE IMMEDIATE
EAST COAST OF MA INCLUDING BOS THROUGH AROUND 16Z. CONFIDENCE
LOWER IN THE POTENTIAL FOR PERIODS OF BKN LOW CLOUDS NEAR THE
CAPE AND ISLANDS ESP LATER IN THE DAY. E-NE WINDS 6-15 KTS WITH
THE STRONGEST NEAR THE COAST. NE WINDS GUST TO BETWEEN 20 AND 25
KNOTS ACROSS THE CAPE AND ESPECIALLY NANTUCKET DURING THE
DAYLIGHT HOURS.
TONIGHT...HIGH CONFIDENCE. MODERATE FOR CEILINGS.
VFR FOR MOST. MVFR-IFR CEILINGS DEVELOP ACROSS CAPE AND ISLANDS
POTENTIALLY REACHING THE EAST COAST AND BOS AFTER MIDNIGHT.
CONFIDENCE IN THE INLAND EXTENT OF THESE CONDITIONS IS LOW AT
THIS TIME BUT COULD EXTEND AS FAR INLAND AS BED.
KBOS TERMINAL...MODER CONFIDENCE IN TAF. THIS IS MAINLY
ATTRIBUTED TO THE TIMING AND PERSISTENCE OF THE STRATUS DECK
THAT'S APPROACHING FROM THE EAST EARLY THIS MORNING.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK /WEDNESDAY THROUGH SATURDAY/...
WEDNESDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. CHANCE SHRA.
WEDNESDAY NIGHT: MAINLY VFR, WITH LOCAL IFR POSSIBLE. BREEZY.
CHANCE SHRA.
THURSDAY: MVFR/IFR CONDITIONS POSSIBLE. BREEZY. SHRA.
THURSDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY.
SLIGHT CHANCE SHRA.
FRIDAY: VFR. BREEZY.
FRIDAY NIGHT: VFR.
SATURDAY: VFR. SLIGHT CHANCE SHRA.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TODAY THROUGH WEDNESDAY..HIGH CONFIDENCE.
HIGH PRESSURE CENTERED OVER THE CANADIAN MARITIMES WITH DISTANT LOW
PRESSURE WELL SOUTHEAST OF THE BENCHMARK CONTINUES NE FLOW THROUGH
MUCH OF THE WEEK. THIS LONG FETCH WILL GENERATE 3 TO 6 FOOT SEAS
ACROSS THE OUTER-WATERS...SO CURRENT SMALL CRAFT HEADLINES WILL
PERSIST THROUGH AT LEAST THURSDAY.
OUTLOOK /WEDNESDAY THROUGH SATURDAY/...
WEDNESDAY: WINDS LESS THAN 25 KT. AREAS OF ROUGH SEAS. CHANCE
OF RAIN SHOWERS, PATCHY FOG.
WEDNESDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF ROUGH SEAS.
CHANCE OF RAIN SHOWERS.
THURSDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS UP
TO 25 KT. AREAS OF ROUGH SEAS. RAIN SHOWERS, SLIGHT CHANCE OF
THUNDERSTORMS.
THURSDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. CHANCE
OF RAIN SHOWERS.
FRIDAY THROUGH FRIDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO
5 FT.
SATURDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT. SLIGHT CHANCE OF RAIN SHOWERS.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR ANZ250-
254>256.
DISCUSSION...MENSCH/FT
AVIATION...BW/MENSCH/FT
MARINE...FRANK/MENSCH
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