BOX issues Area Forecast Discussion (AFD) at Sep 25, 7:13 PM EDT361
FXUS61 KBOX 252313
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
713 PM EDT Thu Sep 25 2025
.SYNOPSIS...
Widespread showers and a few thunderstorms are expected into this
evening as a frontal system moves into the region. Locally heavy
rainfall may produce street flooding, and can't rule out an isolated
strong to severe storm in western New Eng. Improving conditions
Friday with increasing sunshine and warm conditions. The weather
pattern is mostly dry this weekend into next week, but watching
showers to the south may impact the region Saturday night into
Sunday. Mostly warm conditions expected into early next week, then a
strong cold front will deliver a fall airmass by next Wednesday
with temperatures well below normal.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
2PM Update:
Rest of Today and Tonight
Key Messages:
* Continued low risk of severe weather, including a tornado,
mainly across western MA/CT.
* Showers/thunderstorms winding down tonight
A mid-level shortwave lifts northeast this evening into the
overnight hours. Strong integrated water vapor transport ahead of
the associated cold front will support a surge of PWATs up to 2+
inches this afternoon. This will allow for periods of heavy
downpours across southern New England this evening. The latest high-
resolution guidance favors the heaviest rainfall west of Worcester,
where an additional 0.5 to 1 inch of rain is possible through around
midnight with locally higher amounts possible. Elsewhere, expect
more scattered to isolated showers with the potential for a
localized downpour or rumble of thunder.
After midnight, the mid-level trough axis shifts east of the region,
resulting in a wind shift to the west. This will push the
anomalously moist airmass offshore, beginning a drying trend that
will persist into the weekend. Dewpoints will gradually fall
overnight, though still remain elevated enough to support mild low
temperatures in the low to mid 60s.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Tomorrow and Tomorrow Night
Key Messages:
* Warm and humid Friday
* Trending cooler/drier into the weekend
A secondary pulse of shortwave energy crosses southern New England
during the day Friday. Redeveloping low-level southwest flow ahead
of this feature will promote warm air advection, maintaining 925 mb
temperatures in the 1718C range. This will translate to surface
highs in the upper 70s to lower 80s, several degrees above normal.
Despite the mid-level energy, dry air aloft should suppress any
shower activity. Still, a stray shower cannot be ruled out across
southeastern MA where somewhat deeper moisture lingers. Overall,
expect a warm, quiet day with a mix of sun and clouds.
Friday night, west to northwest flow develops as the shortwave exits
offshore. This will usher in cooler and drier air, with PWATs
falling below 1 inch. 925 mb temps dip into the 1012C range. With
clear skies and light winds, efficient radiational cooling will
allow lows to fall into the low to mid 50s across much of the
interior, with upper 50s to lower 60s closer to the coast.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Key Messages:
* Saturday remains dry during the daytime hours, but chances of
showers Saturday night into Sunday morning.
* Above normal temps this weekend into Monday, then turning much
cooler by Wed with a touch of fall
* Humberto expected to remain offshore next week
Expecting the daytime hours of Saturday to remain warm and dry, but
continuing to watch a stream of moisture move northward into
southern New England Saturday evening. GFS remains the most
aggressive (PWATs > 2") and brings a period of showers into the
region Saturday night into Sunday; however, model discrepancies
remain quite large, so confidence is not high at this time. Based on
ensemble probs of 0.1" QPF, we have chance showers south of the MA
Pike Saturday night into Sunday morning. If showers do develop temps
will be several degrees cooler than current forecast (likely in the
60s), but 70s if it remains dry. Warm weather continues into Monday
with potential for 80+, then a cold front pushes southward on
Tuesday, which will bring a fall airmass by Wednesday as a strong
high pressure builds to the north.
A Canadian high and strong front early next week should keep
Humberto offshore. Latest global ensemble tracks are in agreement
that Humberto will remain well to the south before curving offshore.
&&
.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
Tonight...Moderate Confidence
IFR/MVFR ceilings persist for several hours with periods of
-SHRA through about 04-06Z. Low confidence in coverage of
showers, but likely at BAF/BDL. Other terminals will be hit or
miss. Can't rule out an isolated thunderstorm, but latest
observations suggest little thunderstorm activity associated
with a line of showers approaching from the west. Ceilings
should start to improve away from The Cape/Islands terminals
after 09Z. Expect VFR by 12Z everywhere but the Cape/Islands.
Winds prevail from the south/southwest after 06Z with sustained
speeds of 10 knots and some gusts up to 20 knots possible.
Tomorrow...High Confidence
Skies gradually clearing by late morning/early afternoon. Mainly
VFR with MVFR/IFR ceilings over The Cape/Islands through about
15-16Z. VFR likely everywhere after 18Z. West winds around 10
knots.
Tomorrow Night... High Confidence
VFR. Winds becoming northwest 5-10 knots.
KBOS Terminal...Moderate Confidence. MVFR likely with possibly
intermittent periods of both VFR/IFR. Low confidencein shower
potential, but would likely be between 02-04Z. Expect VFR
conditions to return between 10-12Z.
KBDL Terminal...Moderate confidence in TAF.
Outlook /Saturday through Tuesday/...
Saturday: VFR.
Saturday Night through Sunday: VFR. Slight chance SHRA.
Sunday Night through Monday Night: VFR.
Tuesday: Breezy.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight through Friday Night...High Confidence
Seas build to 56 feet across the outer coastal waters overnight,
maintaining Small Craft Advisory conditions through Friday morning.
Conditions gradually improve during the day Friday as seas subside
and winds ease from the west/southwest. A dry cold front crosses the
waters Friday night, shifting winds to the north/northwest with
speeds and gusts generally 10 kt or less. Overall, relatively quiet
boating conditions are expected late Friday night into Saturday
morning.
Outlook /Saturday through Tuesday/...
Saturday: Winds less than 25 kt.
Saturday Night: Winds less than 25 kt. Chance of rain showers.
Sunday through Sunday Night: Winds less than 25 kt. Slight
chance of rain showers.
Monday: Winds less than 25 kt.
Monday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Slight chance of rain showers.
Tuesday: Winds less than 25 kt. Areas of rough seas. Slight
chance of rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 2 AM EDT Friday for ANZ231-251.
Small Craft Advisory until 6 AM EDT Friday for ANZ232>234.
Small Craft Advisory until 8 AM EDT Friday for ANZ250-254.
Small Craft Advisory until noon EDT Friday for ANZ255-256.
&&
$$
SYNOPSIS...RM
NEAR TERM...RM/JWD
SHORT TERM...RM
LONG TERM...McMinn
AVIATION...RM
MARINE...KJC
Source:
BOX issues Area Forecast Discussion (AFD) at Sep 25, 7:13 PM EDT----------------
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