Leominster, Massachusetts 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

353
FXUS61 KBOX 122333
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
733 PM EDT Mon May 12 2025

.SYNOPSIS...
A weak backdoor cold front will drop south through New England
late tonight as high pressure remains over the Maritimes
through Wednesday. Low pressure over the Carolinas Wednesday
will weaken as it approaches the Northeast Thursday and Friday,
then a cold front should cross the region Saturday.

&&

.NEAR TERM /THROUGH TUESDAY/...
Updated 130 PM Mon

Key Message:

 * Continued dry but cooler near coast Tue.

Our area remains under influence of NW-SE oriented ridge from
Great Lakes to Mid Atlantic with one upper low over Maritimes
and another across southeastern states. This pattern stays
locked in through Tue but a weak backdoor front will drop south
through New England, either dissipating or pushing south of New
England Tue morning. Its only effect will be a wind shift to NE,
and with high pressure remaining offshore and a weak gradient,
onshore flow Tue will bring cooler temps to locations near coast
while interior areas have another day of above normal temps.

&&

.SHORT TERM /TUESDAY NIGHT/...
Updated 130 PM Mon

Key Message:

 * Few showers possible late Tue night in western MA/CT.

Ridge axis slowly shifts into northern New England as upper low
over Maritimes exits region. This will also allow the other
closed low over Carolinas to begin to eject northward, but
plenty of dry air should remain over SNE to limit northward
extent of any showers. It`s possible we see a few showers sneak
into western parts of MA/CT late Tue night but that could end up
just being a few sprinkles or brief showers from a mid level
cloud deck.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Updated 130 PM Mon

Key Messages:

 * Pattern turns warmer/more humid into weekend.
 * Best chances for showers/storms Fri and Sat.

Seeing good agreement among longer range guidance which gives us
higher confidence in overall pattern. Weakening upper low from
the south opens up over Northeast later this week as it runs up
into upper ridging that shifts into Maritimes, and is eventually
kicked out by a stronger northern stream closed low which
tracks across southern Canada.

Increasing southerly flow aloft will result in at least a few
showers in Wed-Thu timeframe. We should see more instability
and stronger dynamics ahead of cold front in Fri-Sat timeframe
when showers/storms should be more numerous. CSU ML guidance
also shows a low risk of severe storms both days but pattern
doesn`t look to favorable here in SNE and higher odds are
certainly farther W and SW of our region - something to monitor
in coming days. Later in weekend, broad upper trough remains in
place which should bring at least diurnal clouds if not a few
showers, and onshore flow should also bring cooler temperatures
(closer to average for mid May).

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

00Z TAFs: High confidence.

VFR. SW winds gust to 20-25kt before diminishing this evening
between 00z-002z and shifting to N/NW overnight. E/NE winds
10-15kt Tue diminishing to 10kt or less Tue night.

KBOS TAF...High Confidence in TAF.

KBDL TAF...High Confidence in TAF.

Outlook /Wednesday through Saturday/...

Wednesday: Mainly VFR, with local MVFR possible. Slight chance
SHRA.

Wednesday Night: MVFR/IFR conditions possible. Chance SHRA.

Thursday: Mainly VFR, with areas IFR possible. Chance SHRA,
isolated TSRA.

Thursday Night: Mainly VFR, with areas IFR possible. Slight
chance SHRA.

Friday: Mainly VFR, with local IFR possible. Chance SHRA,
isolated TSRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Updated 130 PM Mon

Overall high confidence through late in the week.

Decided to hoist SCAs for Boston Harbor and most of E MA waters
for 25kt gusts through early this evening based upon seeing
deeper mixing aloft on forecast soundings. Probably marginal for
most but confidence is higher around Cape Cod and Islands,
especially near shore.

Weak backdoor front drops south later tonight which shifts winds
to N/NW, then onshore winds (mainly E/NE) expected Tue and Tue
night but winds and seas stay well below SCA.

Later in week, low pressure over Carolinas weakens as it
approaches Northeast Thu-Fri.

Outlook /Wednesday through Saturday/...

Wednesday: Winds less than 25 kt. Seas locally approaching 5
ft. Slight chance of rain showers.

Wednesday Night through Thursday: Winds less than 25 kt. Areas
of seas approaching 5 ft. Chance of rain showers, isolated
thunderstorms.

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

Friday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ230.
     Small Craft Advisory until 9 PM EDT this evening for
     ANZ231>234-250-254-255.

&&

$$

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