Area Forecast Discussion
Issued by NWS Portland, ME

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418
FXUS61 KGYX 021744
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
144 PM EDT Tue Sep 2 2025

.SYNOPSIS...
Continued fair weather today as high pressure remains in
control. A disturbance moving through Quebec will bring chances
for showers and isolated storms Wednesday afternoon, mainly
north of the foothills. A trough swinging into the Great Lakes
will send a cold front towards New England, bringing increasing
chances for showers Thursday night through Saturday. Showers may
linger in the mountains on Sunday before high pressure brings
dry conditions back for early next week.


&&

.NEAR TERM /THROUGH TONIGHT/...
Terrain induced convection may get tall enough today for some
isolated showers in the White Mtns north to the Canadian border.
However these will do little to alleviate any drought concerns.

Overnight decent radiational cooling conditions remain in place.
More valley fog is anticipated...especially in the lower CT
River Valley. Model guidance also hints at some advection fog
developing overnight. There were patches along the Nova Scotia
coast this morning...however the rest of the Gulf of ME is
rather clear. I did add some patchy fog for the Midcoast...but
did not get too aggressive at this time given the uncertainty.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
Very similar conditions on Wed. Afternoon showers and
thunderstorms are possible once again along the higher terrain.
With a little more wind thru the column Wed these storms could
be a little more robust. Low freezing levels could lead to some
small hail in the strongest storms.

Otherwise the moisture advection continues overnight and model
guidance is a little more bullish on fog for the interior.
Radiational cooling inland combined with the higher dewpoints
advection in over from the waters could result in a band of fog
developing just inland from the shore. I have added patchy fog
in these areas...but made no other significant changes.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Within the longwave troughing over the eastern CONUS, shortwave
ridging aloft moves overhead on Thursday. Once the morning fog
clears up, the ridge will provide a dry and mostly sunny day with
temperatures reaching from the mid 70s to lower 80s. The exception
may be the Midcoast with sea fog hanging near the immediate
coastline.

The ridge then shifts east as a cold front approaches through late
week before eventually crossing late Saturday into Saturday night.
Increasing southerly flow and moisture advection will continue
chances for fog and stratus moving in at night and possibly
continuing over portions of the Midcoast during the daytime Friday
and/or Saturday.

In addition, this will be our best chance of measurable
rainfall this week with multiple rounds of showers possible from
Thursday night through Saturday evening. Diving a little
deeper...the highest of the shower chances during these couple
of days look to be Thursday night into Friday morning as a
shortwave crosses and then again Saturday ahead of the front,
although showers are still possible at other times. Rainfall
amounts are uncertain, but ensembles continue to advertise the
highest probabilities for seeing more than 0.50" of rain across
western and northern NH into the western ME mountains.

Global models remain pretty consistent in bringing the cold front
through the area late Saturday and into Saturday night with showers
gradually coming to an end as drier air begins to move in. The
exception will be in the mountains, where more clouds and upslope
showers may linger into Sunday. Temperatures will be slightly cooler
with mid-upper 60s in the mountains to low 70s to the south.

Conditions continue to dry out early next week with high pressure
building into the Northeast. Daytime temperatures look to remain
fairly similar to those of Sunday. Monday night has the potential
for excellent radiational cooling if we can get the surface
high overhead as currently being advertised.

&&

.AVIATION /17Z TUESDAY THROUGH SATURDAY/...
Short Term...Mostly VFR conditions continue thru Wed night.
Widespread VFR during the day with local IFR or lower each night
in valley fog. There is also some potential for advection fog
tonight and maybe more widespread Wed night. For now I have kept
it near RKD tonight...but that could expand to include
PSM...PWM...and AUG Wed night.

Long Term...Mainly VFR Thursday, but there may be marine fog
and stratus near the coast during the day. A cold front then
approaches the region, bringing multiple opportunities for
showers and possibly thunderstorms Thursday night through
Saturday. Ahead of the front, there will be increasing chances
for IFR to LIFR fog and low stratus, especially at RKD, AUG, and
PWM. The front crosses late Saturday into Saturday night with
mostly VFR Sunday, except there may be a few showers and MVFR
ceilings near HIE on Sunday.

&&

.MARINE...
Short Term...Winds and sea are expected to remain below SCA
thresholds. Both tonight and again Wednesday night some
advection fog may develop. It will likely develop near the
shoreline...but some of the narrow bays and inlets may be
susceptible to lower visibility at times.

Long Term...Conditions are expected to remain below SCA levels
Thursday, but when SCA conditions are possible Friday and/or
Saturday as southerly flow increases ahead of a cold front. In
addition, the potential for marine fog will increase across the
waters. The front crosses Saturday evening into Saturday night
with winds turning west to northwest for Sunday. High pressure
builds across the Northeast early next week, keeping conditions
under SCA levels.

&&

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

&&

$$


NEAR TERM...Legro
SHORT TERM...Legro
LONG TERM...Combs