Leominster, Massachusetts 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

021
FXUS61 KBOX 281915
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
315 PM EDT Thu May 28 2026

.WHAT HAS CHANGED...
A Gale Watch has been issued for all of the coastal and outer
waters for Saturday. Gusty northerly winds are possible with the
passage of a strong low pressure system.

&&

.KEY MESSAGES...

- Isolated showers and thunderstorms develop across eastern MA
today. Cooler and drier conditions arrive Friday.

- Highly anomalous pattern brings a period of rain, strong winds,
and well-below normal temperatures on Saturday.

- Brief drier weather returns for Sunday, but another upper level
low pressure brings scattered diurnally-driven showers and cooler
than normal temps early to mid next week.


&&

.DISCUSSION...
KEY MESSAGE 1...Isolated showers and a thunderstorm or two develop
across eastern MA today. Cooler and drier conditions arrive Friday.

Expecting an uptick in shower activity through the afternoon as a
mid level shortwave rotates southward across the region with an
accompanying increase in moisture. Low-level lapse rates underneath
the disturbance and its associated cold pool steepen to 7-9 C/km.
Best signal for more organized shower activity this afternoon sets
up across eastern MA into RI where the seabreeze pushes inland and
enhances convergence. The showers will wind down this evening as the
shortwave moves to the east followed by subsidence.

Friday is a mainly dry day as the region sits between disturbances.
Will see an increase in mid and high clouds throughout the day as a
potent shortwave begins to dive S from Canada. Highs will be fairly
similar to today if not a few degrees warmer in river valley
locations. Shower chances increase after sunset with increasing
forcing from the incoming vigorous shortwave.

KEY MESSAGE 2... Highly anomalous pattern brings a period of rain,
strong winds, and well-below normal temperatures Friday night and
Saturday.

Deep trough over the eastern CONUS will have a series of stronger
embedded shortwaves as it builds S. First in the series will feature
heights as low as 534 dm, or about 3-5 sigma below climatology!
upper level disturbance will also feature quite the cold pool
with 850mb temps around 0C. In terms of sensible weather,
Saturday will be quite a cold and raw day with highs in the
upper 40s to low 50s for much of the interior. Some guidance
including the NAM even shows a non-zero chance for a few
snowflakes under heavier precip in the Worcester Hills and
Berkshires. Any wintry precipitation would be confined to the
coldest part of the cold pool and with heavier precipitation
rates. In short, this will not be widespread wintry event.

Bigger issue overall will be strong winds on the western edge of
surface low pressure as it deepens just offshore. Guidance has honed
in on the potential for unseasonably strong low level jet (LLJ) on
the order of 55-65kts at 925 mb. At the surface, this may translate
to a period of strong easterly winds Saturday with gusts between 45
and 50 mph across coastal Massachusetts as well as the Cape and
Islands. With fully leafed out trees, winds of this magnitude may
cause areas of tree damage and potential power outages. Saving grace
for this wind event will be limited coverage and duration of the
strongest winds as the bulk of the strongest wind gusts will be over
by 00z.

KEY MESSAGE 3...Brief drier weather returns for Sunday, but another
upper level low pressure brings scattered diurnally-driven showers
and cooler than normal temps early to mid next week.

Blocky 500 mb height pattern governs most of North America, with 500
mb troughing in the mean into at least midweek across the Northeast
United States, downstream of an amplified 500 mb ridge over central
Canada and the north-central tier of states. This background pattern
will tend to support unsettled conditions with a diurnal risk for
scattered, pop-up showers or low-topped thundershowers and
temperatures running cooler than typical early-June normals.

The potent upper low from Fri night/Sat will be moving offshore by
Sat night into Sun. Sun is the pick of the weekend by a wide margin,
with initially clear skies then trending toward partial cloudiness,
but with drier weather and slightly cooler than normal temps in the
mid 60s to lower 70s.

Unfortunately ensemble model-forecast guidance is consistent in
showing another closed mid-/upper-low moving in Sun night from the
northwest, and lingering/meandering around nearby through at least
Tues. It remains unclear how long until this closed low will begin
to exit offshore beyond Tues, with some ensemble members holding
back its eastward passage until Thurs/Fri while others offer drier
weather by Wed.

Frontal forcing is rather nebulous Mon and Tue and will be hard to
focus much activity. This will favor diurnally-driven showers or
possible low-topped thundershowers but with limited severe weather
potential Mon-Tue, the risk being greater during the peak-heating
hours with a minimum around and after sundown. Even still, no one
day necessarily looks to be a washout. Though the forecast has a lot
of mention of Chance-PoPs Mon and Tue, expect there to be scattered
showers/low-topped storms to dodge but several hours of dry weather
in between. Temps each day should end up cooler than normal, in the
mid 60s to lower 70s, with low 60s near the eastern coast.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
Forecaster Confidence Levels...

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

18z TAF Update...

Today...High Confidence.

VFR outside brief scattered showers through the rest of the afternoon
especially across eastern MA. Low risk for an isolated t-storm
or two...But certainly northing widespread. Winds will become
N-NW winds at 10-15 kts with gusts of 20+ kts for the interior
terminals and E-NE 7-13 kts near the eastern MA coast.

Tonight...High confidence.

VFR. Light N-NW wind.

KBOS...High confidence in TAF. The main risk for brief scattered
showers in the vicinity of terminal will be after 18z through
about 00z/01z. There is a low risk for a brief rumble of
thunder as well.

KBDL...High confidence in TAF.

Outlook /Friday through Tuesday/...

Friday: VFR. Breezy.

Friday Night: Mainly VFR, with local MVFR possible. Strong
winds with local gusts up to 40 kt. Chance SHRA, patchy BR.

Saturday: Mainly VFR, with local IFR possible. Strong winds
with areas of gusts up to 40 kt. Chance SHRA.

Saturday Night: VFR. Windy with local gusts up to 30 kt.

Sunday: VFR.

Sunday Night: VFR. Slight chance SHRA.

Monday: VFR. Chance SHRA, slight chance TSRA.

Monday Night: VFR. Chance SHRA.

Tuesday: VFR. Chance SHRA, slight chance TSRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Tonight and Friday...

Generally tranquil with wave heights between 1 and 2 feet for
most of the waters. Winds from the NW between 5 and 10 mph with
gusts as high as 20 mph.

Saturday into Saturday Night...

Gale Watch was upgraded to a Gale  Warning for all the waters
on Saturday due to increased confidence in the strength and
track of an area of low pressure across the region expected to
bring gusty N-NE winds. There is even a chance for areas of
storm force winds with a stronger area of low pressure.


Outlook /Friday through Tuesday/...

Friday: Winds less than 25 kt. Seas locally approaching 5 ft.

Friday Night: Low risk for gale force winds with gusts up to
40 kt. Areas of seas approaching 5 ft. Chance of rain showers,
patchy fog.

Saturday: Moderate risk for gale force winds with local gusts
up to 45 kt. Rough seas up to 12 ft. Rain showers.

Saturday Night: Low risk for Small Craft Advisory winds with
areas of gusts up to 30 kt. Areas of rough seas.

Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft.

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

Monday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Chance of rain showers.

Monday Night through Tuesday: Winds less than 25 kt. Seas
locally approaching 5 ft. Chance of rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Gale Warning from 2 AM to 8 PM EDT Saturday for ANZ230>237-250-
     251-254>256-280>283.

&&

$$

DISCUSSION...Loconto/FT
AVIATION...Frank/FT
MARINE...Mensch/FT