South Berwick, Maine 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

098
FXUS61 KGYX 291845
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
245 PM EDT Sun Jun 29 2025

.SYNOPSIS...
High pressure builds through Monday bringing mostly dry
conditions and a warming trend, as well as increased humidity.
Low pressure tracking through Quebec will drag a cold front
across the area Tuesday bringing chances for thunderstorms, a
few of which may be strong to severe. Outside of some mountain
showers, the middle to second half of next week looks mostly dry
and seasonably warm.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure builds in from the southwest tonight with cloud
cover diminishing with the loss of surface heating. Hi res
guidance suggest fog will develop over the waters and push into
the coast overnight with valley fog likely forming over the
interior. Lows tonight will range from the low 50s north to low
60s south.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
High pressure will settle south of the area Monday for fair
weather and rising temperatures. Highs will climb into the mid
80s to low 90s across the interior. Onshore winds will provide
some cooling near the coast where highs will be closer to 80
degrees.

High pressure shifts southeast Monday night with a warm front
approaching from the southwest. Increased moisture may allow for
more areas of fog along the coastal plain with clouds increasing
west to east towards Tuesday morning. It will be a mild and more
humid night with lows and dewpoints in the 60s.


&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Pattern Overview: The pattern remains unsettled as broad
troughing dominates at the 500 mb level, but periods of more
westerly flow aloft will introduce drier air and keep
precipitation minimal through late week despite a sharper trough
passage (or even a closed low). Deep layer ridging may get a
chance to build back in toward the end of the weekend.


Impacts and Key Messages:
* Tuesday remains a day to watch as warm moist conditions ahead
  of a cold frontal passage may lead to the development of a few
  strong to severe thunderstorms and heavy rain.

Details: Tuesday: Dewpoints increase to the upper 60s and low
70s on southwesterly flow Tuesday morning. However, 850 mb
temperatures will be decreasing, so while the building humidity
will make it feel warmer actual surface temperatures are going
to be a few degrees cooler than Monday. In fact, parts of
southeastern New Hampshire may approach Heat Advisory criteria
as apparent temperatures may feel close to the mid 90s.
Elsewhere, expect it to feel more in the upper 70s north of the
mountains and upper 80s to the south. Low pressure moving out of
the Great Lakes Region looks to drag a cold front through later
on Tuesday and with plenty of moisture and instability in
place, this will be the forcing for afternoon thunderstorms to
develop, a few of which may be strong to severe. The latest LREF
has trended a bit farther south with the higher values of
MUCAPE, but we are still left with 1000-1800 J/kg and deep layer
shear 30-35 kts. This suggests more organized convection, but
the limiting factor looks to be the lapse rates. Now that we are
in the window of the NAMNest, the 12Z run suggests poor lapse
around 5.5 to 6 C/km which may keep things sub-severe. Other
failure modes like timing of the front and cloud cover will have
to be watched as well. SPC has introduced a Day 3 Marginal
Risk. Forecast soundings also show the potential for these
storms (severe or not) to produce very efficient rainfall with
warm cloud depths 12kft+ and feeding on a very moist airmass
with PWATs around 2". Fast storm motions should limit instances
of flooding, but it can`t be ruled out completely. WPC maintains
a Day 3 Marginal Risk for excessive rainfall.

Wednesday and Thursday: Seasonable weather will return as
dewpoints come down behind the front. Wednesday looks to be
mostly dry outside of the mountains, where westerly surface flow
may help sustain a few showers, with full sun helping
temperatures climb into the 80s areawide. Skies remain clear
overnight, with temperatures dropping into the upper 50s and low
60s. Thursday could feature some scattered showers and some
rumbles of thunder as models continue to suggest a sharper
trough digging in from the Great Lakes Region along with an
advancing surface cold front. High temperatures will be similar
to Wednesday with slightly cooler low temperatures Thursday
night.

Friday-Sunday: The July 4th holiday continues to look mostly
dry, but some uncertainty remains with respect to the location
of the trough and an upper low, which the Euro, GFS, and
Canadian now all have. Being in the proximity of an upper low
may equate to more cloud cover and/or a better chance for
periods of showers. This trend will have to be watched, but for
now long range ensembles and the NBM remain on the optimistic
side so I will too.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Short Term...Valley fog will likely bring periods of
restrictions to KLEB, KHIE, KCON, and possibly KMHT. Fog may
develop over the waters and push inland to bring periods of
restrictions along the coastal plain. Conditions improve to VFR
Monday. Fog may become more prevalent Monday night bringing
restrictions to most TAF sites.

Long Term...Thunderstorms look to cross the area on Tuesday
which may bring about brief restrictions to area terminals.
Terminals that see rain during the day may also see some patchy
fog develop briefly on Tuesday night. A frontal passage will
quickly bring conditions back to VFR Wedensday, with that being
the prevailing condition through Friday.

&&

.MARINE...
Short Term...Winds and seas will remain below SCA thresholds
tonight through Monday night. Increasing moisture will likely
bring areas of fog over the waters tonight and again MOnday
night.

Long Term...A brief period of SCA winds and seas are possible
with a frontal passage Tuesday night. This front may also push
thunderstorms and heavy rain across the waters Tuesday evening.
The waters then are on the periphery of high pressure through
Friday with sub-SCA conditions expected. Winds will be generally
southwesterly, with seabreezes likely to develop each
afternoon.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.

&&

$$

NEAR/SHORT TERM...Schroeter
LONG TERM...Baron