647
FXUS61 KGYX 220240
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1040 PM EDT Mon Jul 21 2025

.SYNOPSIS...
High pressure builds in tonight and holds over the Northeast
through mid week. Temperatures moderate through the week, with
increasingly humid conditions by late week as the high moves
onshore. Hot and humid conditions are increasingly likely for
late week. A cold front likely moves through late Friday, with
high pressure returning for the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
1040 PM Update...Mainly made edits to temperatures as northern
and valley locations have decoupled and are beginning to free
fall. Overall, dropped low temperatures another degree or two
with the quick start.

625 PM Update...Just minor changes to align with observed trends
as the forecast remains in great shape. Wind gusts will subside
over the next couple of hours, allowing locations to decouple
overnight and bring about very cool low temperatures.

Previous Discussion...
Breezy but comfortable day underway this afternoon as tight
pressure gradient gradually shifts east. Broad low pressure
moving east of Nova Scotia will continue to bring cool and dry
air into the region overnight. Winds will substantially decrease
this evening, along with the loss of our daytime cumulus.

Once mixing subsides, some parts of the region will see better
decoupling than the others. Points further from the low will
tend to see winds go calm quicker, this includes much of central
and western NH, with higher areas in the Kennebec Valley
remaining somewhat mixed. Regardless, overnight temps will be
cooler still, in the mid 40s to lower 50s. Other than some
valley fog developing, weather conditions remain calm.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
High pressure centers over the region Tuesday, with mostly sunny
skies to start. Temperatures will be more uniform in the 70s for
the forecast area with much lighter winds. NBM winds do show a
wind shift for the coast in the afternoon, likely due to a sea
breeze. HRRR and NAMnest runs depict this more vividly, and
would expect this to begin pushing inland around noontime. This
would likely drop the coastal zones a couple degrees as it
passes, along with more breeze.

Cirrus will be around much of the day, and this cloud cast
should push northeast with time in the evening. Once it does
depart, expect better conditions for radiational cooling Tuesday
night. Blended in some MOS guidance for overnight temps that
will be similar to tonight`s lows.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Overnight Update...No significant changes to the long term
forecast with the implementation of the latest NBM. The focus
remains in Thursday and Friday as building 500 mb heights will
allow 850 mb temperatures to climb into the 18-20C range
bringing about another period of elevated heat and humidity.
Questions remain about conditions for the weekend as guidance
continues to slow down the front, but for now it remains mostly
dry with low chance PoPs.

Previous Discussion...
Overview...

High pressure moves through New England on Wednesday, and
remains east of New England through the end of the week. Heat
and humidity build through late week, with a cold front likely
then crossing on Friday. High pressure returns behind the front
for the weekend.

Details...

Temperatures continue to moderate on Wednesday, with highs
warming into the mid 70s across the north, to the mid 80s across
the south. As the high moves offshore, a southerly flow starts
an upward trend for dew points, but Wednesday remains
comfortable with dew points mainly in the 50s.

By Thursday, the heat and humidity return as highs warm into
the mid 80s across the north, and low to mid 90s across the
south. A southerly flow does keep the coastline cooler, with a
sea breeze moving onshore by the early afternoon. Dew points
will also be on the rise, with dew points in the mid to upper
60s likely for the afternoon hours. This may push heat indices
into the mid 90s across parts of southern New Hampshire and
southwest Maine.

Models appear to be coming to a consensus on a cold front that
we have been monitoring crossing through during the afternoon on
Friday. Some scattered showers and storms ahead of the front
may reach northern areas late Thursday, but would be weakening
as they arrive. Thursday night then looks sticky, with lows
mainly in the 70s.

The heat peaks on Friday, with widespread 90s south of the
mountains, and mid to upper 90s likely across southern
locations. Heat indices may reach the triple digits in these
areas on Friday. Further north, showers and storms associated
with the front are most likely to arrive by the early afternoon
and help keep highs to the low 80s. As the front moves southward
during the afternoon, showers and storms likely accompany the
front, and some could be strong given the heat ahead of the
front.

The front slows as it moves through, likely only making it just
south of the area by Saturday. This brings some relatively
cooler and drier air to the area, but 80s look most likely
across the area with dew points still in the mid 60s across the
south. The timing and progress of the front remains the
determining factor on storms and Saturday temperatures. The
trend over the last few days has only been for the front to be
slower and less progressive, and there`s no signals otherwise at
this point. So that`s how it looks now, but it will be worth
monitoring over the next few days to see just how much of a
difference this front ends up making for the the weekend
conditions.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Short Term...VFR with breezy NW winds subsiding this evening.
Valley fog may develop along the CT River Valley tonight, mainly
impacting HIE and LEB. Can`t rule out other low valley fog
elsewhere in vicinity to inland terminals. Mainly high cirrus
for Tuesday under high pressure. Winds will have lightened,
although a sea breeze may invade coastal terminals around noon
local time.

Long Term...VFR prevails during the daytime at all terminals on
Wednesday. Marine fog is possible at RKD on Thursday and
Friday, with VFR prevailing elsewhere. Nighttime valley fog is
possible each night at LEB and HIE. Brief periods of showers and
thunderstorms are possible at all terminals on Friday. VFR then
likely returns for the weekend.

&&

.MARINE...
Short Term...Breezy conditions this morning and afternoon should
subside this evening. While some gusts will reach 25 kts early
this afternoon, do not expect SCA to be needed. High pressure
centers over the area Tuesday.

Long Term...Fair conditions prevail with high pressure on
Wednesday. The high then moves east of the waters, with areas of
fog possible on Thursday and Friday. A cold front approaches
from the west on Thursday and Friday, with SCA conditions in
southwesterly flow possible by late Thursday, and continuing
until the frontal passage Friday night. High pressure then
returns to the waters this weekend.

&&

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

&&

$$

NEAR TERM...Baron/Cornwell
SHORT TERM...Cornwell
LONG TERM...Baron/Clair