930
FXUS61 KBOX 172334
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
734 PM EDT Thu Jul 17 2025

.SYNOPSIS...
An approaching cold front may bring a brief shower through this
evening. Behind the front, cooler and much less humid air will
follow Friday and Saturday. Another cold front will likely
bring a round of showers and thunderstorms to the region
Sunday. High pressure will bring dry weather with near normal
temperatures early next week.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Key Messages...

 * Few showers or a thunderstorm possible in northern MA this
   evening.
 * Drier air works into the region overnight.

Line of showers ahead of the cold front was moving through
southern NH this evening. Drier air aloft has already worked
into region and has limited shower/thunderstorm development
despite plenty of instability. It`s possible the southern end of
this line develops more into northern MA this evening, perhaps
even with an embedded thunderstorm, but farther to the south dry
weather should prevail.

Cold front will work through SNE tonight, bringing an end to the
heat and humidity.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Key Messages...

* Cold front brings relief from high heat and humidity

Details...

Friday...

Any showers that spring up this afternoon and evening will exit
southern New England overnight. A drier airmass moves in post-
FROPA, bringing much needed relief from the high heat and
humidity heading into the weekend. Mostly sunny & beautiful
weather for Fri with highs mainly between 80 and 85 and very
comfortable humidity levels.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Key Messages...

* Another round of showers and thunderstorms late Sat night-Sun.

* Dry with average temps most of next week - warms up again Wed/Thu.

Northern stream dominates into next week which suppresses
subtropical ridge and keeps the heat/humidity away, though as we
head toward the end of next week there are signs the ridge may
return and bring increasing heat and humidity by Thu (although
probably not to the levels we saw this week).

Overall, dry weather should dominate with the exception of late
Sat night into Sun, when low pressure tracking to our NW brings
a round of showers/storms. ML guidance shows a low risk of
severe storms with environment featuring decent instability with
surface CAPE up to 2000 J/kg across interior and strong 0-6km
shear of 35-45kt, but as usual mid level lapse rates look fairly
weak. Moisture convergence looks impressive, however, with a
decent theta-e ridge over SNE and PWATs climbing to around 2",
so any storms could produce localized downpours and street
flooding, but not seeing much of a signal for flash flooding
right now (even in ML guidance).

&&

.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. Exception is near Cape Cod and Islands where persistent SW
flow has maintained IFR conditions, but this should erode
quickly toward midnight as cold front comes through and shifts
winds to W/NW. Most airports should see some 20-25kt gusts
overnight into Fri morning as cooler/drier air arrives, then
winds become N and diminish Fri afternoon and evening.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Saturday through Tuesday/...

Saturday: VFR. Breezy.

Saturday Night: Mainly VFR, with areas MVFR possible. Breezy.
SHRA likely, chance TSRA.

Sunday: Mainly VFR, with local MVFR possible. Breezy. Slight
chance SHRA, slight chance TSRA.

Sunday Night through Monday Night: VFR.

Tuesday:

&&

.MARINE...
Forecaster Confidence Levels...

Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.

High confidence through Sat.

SCAs remain posted for 25kt gusts through early tonight on most
of south coastal waters, and for outer waters into Fri due to
lingering 5 ft seas as well as NW winds gusting to 25kt behind
cold front. Winds and seas diminish Fri afternoon as high
pressure builds over waters, with generally light winds and calm
seas into Sat.

Outlook /Saturday night through Tuesday/...

Saturday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas locally approaching 5 ft. Chance of rain
showers, slight chance of thunderstorms.

Sunday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers, slight chance of thunderstorms.

Sunday Night through Tuesday: Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 2 AM EDT Friday for ANZ231>237.
     Small Craft Advisory until 2 PM EDT Friday for ANZ250-251-
     254>256.

&&

$$

SYNOPSIS...JWD
NEAR TERM...JWD
SHORT TERM...McMinn
LONG TERM...JWD
AVIATION...JWD
MARINE...JWD