134
FXUS61 KBOX 082317
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
717 PM EDT THU OCT 8 2026
WHAT HAS CHANGED
CONFIDENCE HAS INCREASED IN THE ARRIVAL OF REMNANT TROPICAL
MOISTURE SUNDAY AFTERNOON/EVENING, WITH THE HEAVIEST RAINFALL
FAVORING THE SOUTH COAST AND IMPROVING CONDITIONS EXPECTED LATER
MONDAY.
KEY MESSAGES
- MOSTLY CLEAR TO PARTLY CLOUDY THROUGH FRIDAY NIGHT, WITH
WESTERLY AFTERNOON BREEZES IN THE 20 TO 30 MPH RANGE. FROST
POSSIBLE FRIDAY NIGHT.
- SUNNY AND DRY FOR SATURDAY WITH LIGHT WINDS.
- RAIN IS INCREASINGLY LIKELY SUNDAY AFTERNOON INTO COLUMBUS
DAY AS REMNANT TROPICAL MOISTURE MOVES INTO SOUTHERN NEW
ENGLAND. A SOAKING RAIN IS POSSIBLE, ESPECIALLY NEAR THE SOUTH
COAST, BEFORE CONDITIONS IMPROVE LATER MONDAY. ADDITIONAL
SHOWERS TUESDAY, THEN COOLER WEDNESDAY.
DISCUSSION
KEY MESSAGE 1...MOSTLY CLEAR TO PARTLY CLOUDY THROUGH FRIDAY NIGHT,
WITH WESTERLY AFTERNOON BREEZES IN THE 20 TO 30 MPH RANGE. FROST
POSSIBLE FRIDAY NIGHT.
MAIN SYNOPTIC-SCALE FEATURES OF INTEREST THROUGH FRIDAY NIGHT IS A
BROAD CYCLONIC MID-LEVEL FLOW ALOFT ACROSS THE US/CANADA BORDER,
WITH AN EXPANSIVE 1024-1028 MB SURFACE HIGH PRESSURE FROM THE GT
LAKES REGION TO THE NORTHERN MID-ATLANTIC, WHICH MOVES INTO SOUTHERN
NEW ENGLAND BY LATE FRIDAY NIGHT INTO SATURDAY.
THERE IS AN EMBEDDED MID-LEVEL SHORTWAVE DISTURBANCE MOVING THROUGH
THE BROADER CYCLONIC FLOW, WHICH COULD SPARK ISOLATED POP-UP SHOWERS
ESPECIALLY NORTH OF THE MASS PIKE THROUGH THIS AFTERNOON, BUT THE
VAST MAJORITY OF THE TIME THROUGH TODAY IS DRY.
THE MID/UPPER LEVEL TROUGH WILL MAINTAIN A COOLING BOUNDARY LAYER
WITH STRONG DIURNAL MIXING FOR THE REST OF TODAY AND AGAIN ON
FRIDAY. MIXING DEPTH PROGS SHOW THE TOP OF THE PBL AS HIGH AS 800
MB, WITH WESTERLY JET OF 3O TO 35 KT PROGGED ON THE NAM/GFS. THIS
WILL SUPPORT WESTERLY BREEZES AND FALLING DEWPOINT TEMPERATURES,
BOTH THIS AFTERNOON AND AGAIN BY FRIDAY MID-MORNING UNTIL SUNDOWN.
WESTERLY GUSTS THROUGH SUNDOWN TODAY IN THE 20-25 MPH RANGE
WITH GUSTS UP TO 30 MPH, AND SHOULD BE A SIMILAR IF NOT UP TO 5
MPH HIGHER ON FRIDAY. HIGHS MAINLY IN THE MID 60S FOR FRIDAY
WITH MOSTLY SUNNY SKIES.
THE HIGH PRESSURE OVER THE MID-ATLANTIC STATES BEGINS TO SHIFT
EASTWARD INTO SOUTHERN NEW ENGLAND FRIDAY NIGHT, WITH DECREASING
WINDS AND INCREASINGLY EFFICIENT RADIATIONAL COOLING. THE TIMING OF
WIND CESSATION - WHICH HINGES ON HOW QUICKLY WILL THE HIGH MOVE IN -
WILL BE IMPORTANT ON LOW TEMPS AND IF FROST CAN DEVELOP, BUT HAVE
SHOWN LOWS FRIDAY NIGHT IN THE MID/UPPER 30S IN THE TYPICALLY COOLER
OUTLYING LOCATIONS AND THE LOW TO MID 40S FOR THE URBAN CENTERS AND
THE COASTLINES. THAT COULD WARRANT FROST HEADLINES FOR PARTS OF THE
AREA PENDING HOW QUICKLY WINDS EASE UP.
KEY MESSAGE 2...SUNNY AND DRY FOR SATURDAY WITH LIGHT WINDS.
SATURDAY IS THE PICK OF THE WEEKEND, AS HIGH PRESSURE CRESTS OVER
SOUTHERN NEW ENGLAND, THEN MOVES OFFSHORE INTO SATURDAY EVENING.
AFTER A BIT OF A CHILLY START, HIGHS SHOULD REBOUND BACK INTO THE
LOW TO MID 60S UNDER FULL SUN. WITH LIGHT WINDS, IT'S A GREAT DAY
FOR ANY OUTDOOR PLANS. WARM ADVECTION TAKES PLACE SATURDAY EVENING
AND WITH A MODEST INCREASE IN SE WINDS, LOWS SHOULD BE QUITE A BIT
MILDER THAN FRIDAY NIGHT, IN THE MID 40S TO LOW 50S.
KEY MESSAGE 3...RAIN IS INCREASINGLY LIKELY SUNDAY AFTERNOON
INTO COLUMBUS DAY AS REMNANT TROPICAL MOISTURE MOVES INTO
SOUTHERN NEW ENGLAND. A SOAKING RAIN IS POSSIBLE, ESPECIALLY
NEAR THE SOUTH COAST, BEFORE CONDITIONS IMPROVE LATER MONDAY.
ADDITIONAL SHOWERS TUESDAY, THEN COOLER WEDNESDAY.
GUIDANCE CONTINUES TO COME INTO BETTER AGREEMENT REGARDING THE
ARRIVAL OF REMNANT MOISTURE FROM ISAIAS, WITH RAIN INCREASINGLY
LIKELY SUNDAY AFTERNOON/EVENING AND CONTINUING INTO COLUMBUS DAY.
IMPORTANT TO EMPHASIZE THAT SOUTHERN NEW ENGLAND WILL NOT BE
DIRECTLY IMPACTED BY A TROPICAL SYSTEM, BUT RATHER MOISTURE
ASSOCIATED WITH WHAT WAS ONCE A TROPICAL SYSTEM. WHILE CONFIDENCE IN
THE TIMING HAS INCREASED, UNCERTAINTY REMAINS REGARDING HOW FAR
NORTH THE PRECIPITATION SHIELD EXTENDS. THE HEAVIEST RAINFALL
CONTINUES TO FAVOR AREAS CLOSER TO THE SOUTH COAST. FORTUNATELY,
THIS LOOKS TO BE A FAIRLY PROGRESSIVE SYSTEM, WITH CONDITIONS
IMPROVING DURING THE SECOND HALF OF MONDAY.
THERE REMAINS POTENTIAL FOR A SOAKING RAIN, ESPECIALLY ACROSS
SOUTHERN PORTIONS OF THE REGION. DESI PROBABILITIES FOR 0.50+ INCHES
OF RAINFALL, FROM 8PM SUNDAY TO 8PM MONDAY, REMAIN AROUND 45 PERCENT
ACROSS NORTHERN MASSACHUSETTS, INCREASING TO 60-75 PERCENT ALONG AND
SOUTH OF HARTFORD, PROVIDENCE AND TAUNTON. CANNOT RULE OUT LOCALLY
HIGHER AMOUNTS, WITH PROBABILITIES FOR 2+ INCHES AROUND 10-20
PERCENT FROM MONTAUK POINT THROUGH COASTAL RHODE ISLAND, INCLUDING
BLOCK ISLAND, INTO SOUTHEAST MASSACHUSETTS AND THE ISLANDS. GIVEN
THE PROGRESSIVE NATURE OF THIS SYSTEM, THE OVERALL FLOODING THREAT
APPEARS LOW, THOUGH CANNOT COMPLETELY DISMISS LOCALIZED POOR
DRAINAGE FLOODING, ESPECIALLY WHERE FALLEN LEAVES MAY CLOG STORM
DRAINS. WHILE THE SEVERE WEATHER THREAT REMAINS UNCERTAIN, THE
TROPICAL ORIGINS OF THIS MOISTURE WARRANT CONTINUED MONITORING FOR
ANY LOW-END SEVERE POTENTIAL.
A BRIEF LULL IN PRECIPITATION IS ANTICIPATED LATE MONDAY INTO EARLY
TUESDAY BEFORE ANOTHER ROUND OF SHOWERS ACCOMPANIES A COLD FRONT
TUESDAY. TEMPERATURES REMAIN MILD BY OCTOBER STANDARDS AHEAD OF THE
FRONT, WITH HIGHS IN THE UPPER 60S TO LOWER 70S SUNDAY THROUGH
TUESDAY. DEWPOINTS INCREASE INTO THE MIDDLE TO UPPER 50S SUNDAY,
THEN INTO THE 60S MONDAY AND TUESDAY. BEHIND THE FRONT, A COOLER AND
DRIER AIRMASS ARRIVES WEDNESDAY, WITH HIGHS RETURNING TO THE UPPER
50S TO LOWER 60S AND DEWPOINTS FALLING INTO THE 40S TO LOWER 50S.
AVIATION /00Z FRIDAY THROUGH TUESDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
00Z TAF UPDATE...HIGH CONFIDENCE.
VFR CONDITIONS CONTINUE THROUGH FRIDAY. INITIALLY GUSTY W/NW
WINDS RELAX OVERNIGHT TO BETWEEN 5-10 MPH AT MOST TERMINALS.
VFR FRIDAY WITH W WIND 10-15 KTS GUSTING TO 20 TO 30 KTS THROUGH
THE AFTERNOON. COULD SEE A SCT LAYER DEVELOP AT 045, BUT
OTHERWISE FRIDAY IS A VFR DAY.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK /FRIDAY NIGHT THROUGH TUESDAY/...
SATURDAY THROUGH SUNDAY: VFR.
SUNDAY NIGHT: MVFR/IFR CONDITIONS POSSIBLE. SHRA LIKELY.
COLUMBUS DAY: MAINLY VFR, WITH LOCAL IFR POSSIBLE. SLIGHT
CHANCE SHRA.
MONDAY NIGHT: VFR.
TUESDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY. SLIGHT
CHANCE SHRA.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
THROUGH FRIDAY NIGHT: HIGH CONFIDENCE.
SMALL CRAFT ADVISORIES REMAIN IN EFFECT THROUGH 7 PM THIS EVENING,
AS WESTERLY WINDS HAVE BEEN GUSTING IN THE 25 TO 30 KT RANGE ON MOST
WATERS AND SHOULD REMAIN SO THROUGH SUNDOWN. ALTHOUGH WINDS SHOULD
EASE SOME INTO TONIGHT TO AROUND 10-15 KT, WE WESTERLY GUSTS RESUME
IN THE SCA RANGE (25-30 KT) STARTING FRIDAY MID TO LATE MORNING
THROUGH THE AFTERNOON WITH STRONG MIXING EXPECTED OVER THE WATERS.
WE'LL LIKELY NEED TO RE-ISSUE SCAS FOR MOST WATERS ONCE THE EXISTING
ONES EXPIRE. SEAS AROUND 4 FT OR LESS FOR ALL WATERS, WITH GOOD
VISIBILITY EXPECTED.
OUTLOOK /FRIDAY NIGHT THROUGH TUESDAY/...
SATURDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING 5 FT.
SATURDAY NIGHT THROUGH SUNDAY: WINDS LESS THAN 25 KT.
SUNDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING
5 FT. RAIN SHOWERS LIKELY.
COLUMBUS DAY: WINDS LESS THAN 25 KT. AREAS OF ROUGH SEAS.
CHANCE OF RAIN SHOWERS.
MONDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF ROUGH SEAS.
SLIGHT CHANCE OF RAIN SHOWERS.
TUESDAY: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. SLIGHT CHANCE
OF RAIN SHOWERS.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
ANZ230>237-250-251-254>256.
DISCUSSION...LOCONTO/DOOLEY
AVIATION...LOCONTO/FT
MARINE...LOCONTO/DOOLEY
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