638
FXUS61 KBOX 261914
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
314 PM EDT Wed Mar 26 2025

.SYNOPSIS...
A fast moving disturbance may trigger a few brief passing rain/high
terrain snow showers through this evening. Dry and pleasant weather
follows for Friday. Periods of unsettled weather are on tap Friday
night through Monday with temperatures highly uncertain depending on
the location of a backdoor front, but leaning towards temperatures
being on the chilly side except perhaps for parts of Connecticut and
southwest Massachusetts.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Key Messages:

* A few showers will exit the coast later this evening
* Clearing and colder overnight

Mid level low moving across northern New Eng this afternoon will
exit to the NE this evening. Cold pool aloft with -36C at 500 mb
will contribute to steep low-mid level lapse rates resulting in
widely scattered rain or higher elevation snow showers moving
across SNE through late afternoon with showers exiting SE New
Eng later this evening. Behind the departing mid level low,
drier air will move into the region with clearing skies
developing overnight. Decent pressure gradient in place tonight
will result in a steady NW flow which will limit radiational
cooling but modest cold advection will allow low temps to to
drop into the upper 20s inland and lower 30s near the coast.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Thursday...

Weak shortwave ridging builds into the region between mid level
low to the NE and approaching shortwave dropping SE from
Canada. Subsidence and rather dry air in the column will result
in abundant sunshine and it will become breezy with deep and
well mixed boundary layer. NW winds are expected to gusts to 25
mph. The deep mixing will also contribute to very dry air with
dewpoints dropping through the teens. 850 mb temps around -6C
during the afternoon which translates to high temps ranging from
low-mid 40s northern MA higher terrain to around 50 in the
coastal plain which is close to normal for late March.

Thursday night...

The aforementioned shortwave from Canada will move into New Eng
late evening and may be accompanied by a few rain or snow
showers as a slight increase in PWATs noted ahead of the
attendant cold front. At the very least an increase in cloud
cover is expected. Winds will turn to the SW 5-15 mph ahead of
the front with lows in the low-mid 30s, except upper 20s higher
elevations. FROPA expected by daybreak followed by with a wind
shift to W-NW and clearing skies.

&&

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

* Dry & pleasant on Friday with highs mainly in the 50s

* Periods of unsettled/wet weather Sat through Mon with backdoor
  cold in the vicinity of SNE. Highs in the 30s/40s north of the
  front and 60s/70s to the south of the boundary

* Warm Mon, but high pressure settles in Tues and Weds bringing
  another round of cooler temps and dry wx.

Details...

Friday...

A brief ridge of high pressure builds in behind the shortwave on Fri
allowing for a pleasant day overall. High temps likely to be in the
mid 50s across the CWA. Some WNW wind gusts of 20+ mph are possible.
Can`t rule out a stray shower or two Friday, especially across the
southern shores, Cape, and Islands.

Friday night through Monday...

A tricky forecast for the weekend... At the same time as a low
pressure system in the central Plains lifts northeastward towards
the Great Lakes, a strong high pressure builds over the James Bay.
Ensemble guidance is suggesting this high tops out around 1030mb at
the surface on Saturday which will allow for a backdoor cold front
to push south into southern New England. Uncertainty is still rather
high regarding how far south the front will drop, but it is
increasingly likely it may bisect somewhere across southern New
England for a period of time. High temps Saturday will likely
struggle to reach 45F north of the front; however, high temps south
of the front have a pretty good chance to reach 70F.

It also looks quite unsettled for the weekend, with wet weather
likely across most of the CWA. Saturday in particular looks to have
widespread rain for most of the day while Sunday looks to have
intermittent periods of drying. Rain will be the predominant precip
type; however, given the strength of the high over the James Bay, we
can`t rule out the low risk for a bit of snow/ice across the
interior high terrain along the MA/NH/VT line.

The backdoor cold front looks to lift out of SNE on Monday as the
low over the Great Leaks moves further north into southern Ontario.
As the low moves closer, winds will become primarily south-
southwesterly and bring a surge of warmer air to the area... likely
resulting in warmer temps for the day.

Tuesday & Wednesday...

The middle of next week is also quite tricky to nail down given high
uncertainty this far out. Regardless, the low over southern Ontario
looks to lift out, and a high is likely to build in over the Great
Lakes Tuesday and Wednesday. This setup will likely bring another
round of cold, dry, Canadian air into southern New England, and
limit temperatures across the CWA.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

18z TAF Update...

Through 00z...

MVFR cigs over Cape/Islands will improve to VFR 19-20z.
Otherwise VFR cigs 5-8k ft with a few rain showers developing,
possibly snow showers higher terrain.

Tonight...High Confidence.

A few showers possible across SE MA and Cape/Islands this
evening, otherwise clearing skies. WNW winds 5-10 knots.

Thursday...High Confidence.

VFR. WNW winds 8-15 kt with gusts to 20-25 kt

Thursday night...High confidence.

VFR cigs developing. A few rain or snow showers possible. Winds
turning SW 8-15 kt.

BOS TAF...High confidence. Sea-breeze wind will shift to NW
around 00z.

BDL TAF...High confidence.

Outlook /Friday through Monday/...

Friday: VFR. Breezy.

Friday Night: MVFR/IFR conditions possible. RA likely.

Saturday: MVFR/IFR conditions possible. Breezy. Chance RA.

Saturday Night through Sunday: MVFR/IFR conditions possible.
Chance RA, FZRA likely.

Sunday Night: MVFR/IFR conditions possible. Breezy. RA likely.

Monday: MVFR/IFR conditions possible. Breezy. Chance RA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight through Thursday night: High Confidence.

Increasing NW winds tonight behind a upper level trough passage with
winds increasing to 15-20 kt with a few higher gusts. Similar winds
speeds Thu with NW flow becoming W during the afternoon. We may see
some 25 kt gusts in the Thu afternoon/evening over southern waters
and SCA may eventually be needed. Another approaching shortwave will
bring increasing SW wind gusts to 25 kt overnight Thu night. Seas
expected to build to 5 ft over southern waters late Thu and Thu
night.

Outlook /Friday through Monday/...

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

Friday Night: Winds less than 25 kt. Chance of rain.

Saturday through Saturday Night: Winds less than 25 kt. Local
rough seas. Chance of rain.

Sunday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain.

Sunday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Rain likely.

Monday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of rough seas. Chance of rain.

&&

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

&&

$$

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