633
FXUS61 KBOX 011805
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
205 PM EDT Mon Sep 1 2025

.SYNOPSIS...
High pressure remains in control through at least Thursday, bringing
an extended stretch of dry weather and seasonably warm temperatures.
Turns more humid by Friday, with an approaching cold front bringing
showers and a chance of thunderstorms. Warm and humid conditions and
risk for showers linger into Saturday ahead of the cold front, then
cooler and drier weather returns next Sunday and Monday behind
the cold front with slightly below normal temperatures.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Messages:

* Cool night with light winds. Decreasing cloud cover with some
  patchy late night fog possible

Upper low over the mid Atlc region will lift northward tonight
through New York. As it does high clouds will move north with
partial clearing developing from the south tonight. With high
pres in control and light winds radiational cooling will allow
low temps to fall to 50-55 for most locations with some upper
40s in the coldest radiators, but upper 50s urban centers.
Patchy radiation fog is possible in the normally prone
locations.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
Key Messages:

* Mostly sunny Tue with onshore flow and highs in the 70s
* Another cool night Tue night with light winds

Tuesday...

Upper low and canopy of high clouds will be well to the north
resulting in a mostly sunny day. There is some slight warming at 925
mb so highs should be 1-2 degrees warmer Tue with highs mid-upper
70s. But high pres from Maritimes to New Eng will maintain a low
level NE flow which will keep temps coolest near the eastern
MA coast.

SE swell forecast is a bit less on Tue, around 3-4 ft over SE waters
so opting not to issue a rip current statement. Highest risk for rip
currents will be at Nantucket beaches where risk is in the moderate
category.

Tuesday night...

A good radiational cooling night with high pres overhead with clear
skies, light winds and dry airmass. Expect similar low temps 50-55,
with mid-upper 40s in the colder radiators in western MA and
interior eastern MA. Can`t rule out patchy late night fog developing.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Key Messages:

* Dry with seasonable temperatures Wednesday and Thursday.

* Next chance for rainfall arrives by Friday with rain and a some
  embedded thunderstorms possible later in the day.

* Front moves through by Sunday bringing slightly below normal
  temperatures for Sun/Mon.

Deterministic/ensemble guidance show the extended period to be
dominated by an upper ridge across the western CONUS and troughing
across the east.

Wednesday and Thursday are favored to be dry with a center of high
pressure positioned offshore of southern New England. Wednesday
850mb temperatures warm up to around +10C and with sufficient mixing
will help yield highs in the 70s. A few spots in the valleys may hit
80. SE flow will keep the south-facing coastal areas a touch cooler
in the lower 70s. On Thursday, high pressure will weaken through the
day in response to an upper level trough shifting eastward across
the Great Lakes region. Thursday should still remain dry with
temperatures in the 70s to around 80.

An upper low center slowly moves across eastern Canada before
lifting north Thursday through the first half of the weekend.
Ensemble guidance keeps the associated trough and shortwave energy
to the north and west of southern New England as it tracks closer to
the northeast on Friday. Forcing will be more limited; however,
there should be weak ascent and sufficient moisture to support rain
Friday. There will be sufficient instability in place later Friday
which may support embedded thunderstorms. Across ensemble guidance,
the highest probabilities for rain amounts are in the 0.01-0.50"
range with the best chances for the upper range in western parts of
the region. With the potential for embedded thunderstorms and above
normal moisture present, localized areas may receive high
amounts of rainfall. We`ll be able to tap into more detail as we
get closer.. Dry air/high pressure offshore and limited forcing
may keep the Cape/Islands on the lower end of the rainfall
range. Temperatures should range in the mid 70s to near 80 with
higher humidity with breezy SW winds.

Model guidance hints at another brief wave that may bring a
secondary round of scattered light showers on Saturday. We still
remain in the "warmer" airmass on Saturday which will support
similar temperatures/humidity levels to Friday.

A cold front will push through later Saturday into early Sunday
bringing back cooler highs and lower humidity Sunday and Monday.
Highs will likely range slightly below normal in the lower 70s
and even some upper 60s in the higher terrain spots.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...

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

18z TAF Update:

Tonight through Tuesday night...High confidence.

VFR through the period. Patchy late night radiation fog possible
tonight and Tue night at BAF, BDL and BED.

NE winds 5-15 kt this afternoon becoming light to calm tonight. E-
NE wind 5-15 kt Tue then light to calm again Tue night.

KBOS TAF...High confidence in TAF.

KBDL TAF...High confidence in TAF. Low risk of late night
patchy fog after 07z.

Outlook /Wednesday through Saturday/...

Wednesday through Wednesday Night: VFR.

Thursday: VFR. Breezy.

Thursday Night: Mainly VFR, with local IFR possible. Breezy.
Chance SHRA.

Friday: Mainly VFR, with local IFR possible. Breezy. Chance
SHRA, slight chance TSRA.

Friday Night: VFR. Breezy. Chance SHRA.

Saturday: VFR. Breezy. Chance SHRA, chance TSRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Tue night...High confidence.

E-NE winds averaging 5-15 kt through Tue becoming light and variable
Tue night. Seas will remain below SCA thresholds, peaking around 4
ft over waters south and east of the Islands.

Outlook /Wednesday through Saturday/...

Wednesday through Wednesday Night: Winds less than 25 kt. Seas
locally approaching 5 ft.

Thursday: Winds less than 25 kt.

Thursday Night: Winds less than 25 kt. Slight chance of rain
showers.

Friday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas locally approaching 5 ft. Slight chance of rain
showers.

Friday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Slight chance of rain showers.

Saturday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of seas approaching 5 ft. Chance of rain
showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

SYNOPSIS...KJC/Mensch
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...Mensch
AVIATION...KJC/Mensch
MARINE...KJC/Mensch