948
FXUS61 KGYX 031022
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
622 AM EDT Wed Sep 3 2025

.SYNOPSIS...
A disturbance moving through Quebec will bring chances for
showers and isolated storms this 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 into Friday. Another front approaches for
Saturday perhaps allowing for more substantial rainfall and
thunderstorms over a wider area. High pressure moves in early
next week.

&&

.NEAR TERM /THROUGH TODAY/...
620 AM Update...Just minor changes to align with observations
early this morning as the forecast remains on track. Pockets of
dense fog developed overnight and are present currently in the
Midcoast area. This will clear in the next couple hours giving
way to clear skies and building instability away from the
coast.

Previous Discussion...
Impacts and Key Messages:
* No significant weather impacts are expected.

The few showers that had developed in northern New Hampshire
late last evening have dissipated and fog will begin to fill
into the Connecticut River Valley through the early morning
hours. Nighttime microphysics satellite at this hour is also
starting to show signs of fog development on the Midcoast as
well.

Fog clears these locations early on this morning giving way to
clear skies across the area. Temperatures climb into the mid- to
upper 70s areawide, with valley locations touching 80. The
latest HREF suggests daytime heating will aid in the development
of 300-500 J/kg of CAPE in the mountains and foothills, with
the coastal plain and southern New Hampshire staying more stable
with the onshore flow. As a result, an approaching shortwave
combined with orographic lift initiates showers and
thunderstorms in the mountains during the afternoon and evening
hours. The latest CAMs suggest some of these may spill into
foothills, but lack of any additional synoptic forcing should
keep them from developing any further south. Shear only around
20kts and lapse rates only around 6 C/km should preclude any
kind of a severe threat, but this is sufficient enough for a
stronger storm to form. Forecast soundings suggest low freezing
levels and steep low level lapse rates which mean those storms
that do grow taller may be capable of producing small hail and
gusty winds.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
Impacts and Key Messages:
* No significant weather impacts are expected.

Tonight: With loss of daytime heating and subtle 500mb height
rises, any showers and storms will dissipate after sunset with
skies clearing early on in the night as well. This should lead
to another night with some degree of radiational cooling. As a
result temperatures should fall into the mid- to upper 40s north
of the mountains and in the valleys, and into the low to mid
50s south of the mountains. Continued southerly flow increases
low level moisture and looks to develop marine and coastal fog,
with radiation fog in the valleys.

Thursday: Once daytime mixing clears out any fog Thursday, it
will be a mostly clear day. Deep mixing will once again allow
some drier dewpoints to mix down and drop relative humidity
values into the 35-45% range. On the coastal plain, where
continued southerly flow continues to advect moisture onshore,
dewpoints and relative humidity values will remain higher.
Temperatures climb into the mid- to upper 70s areawide once
again, with valley locations touching 80. As a front makes its
approach Thursday afternoon and evening, a tightening pressure
gradient looks to kick up some breezy southerly wind gusts in
the range of 15 to 20 mph, with some 25 mph gusts not out of the
question.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Early morning long term update...The 01z NBM and various other
ensembles and deterministics are in reasonable agreement through
the weekend although details need to be worked out going
forward. A cold front approaches Thursday night with a chance of
showers and perhaps a thunderstorm but the timing with with
respect to diurnal heating will likely only allow a weakening
line of showers to move through overnight into Friday morning. A
more substantial threat for showers and thunderstorms appears
to be possible with the next short wave trough which arrives
Saturday during a more favorable portion of the day for heating
and subsequent instability.

Previously...

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 /10Z WEDNESDAY THROUGH SUNDAY/...
Short Term...Fog clears from impacted terminals early this
morning, with VFR prevailing through the day. Showers and
thunderstorms develop in the afternoon, mainly in the mountains
and foot hills with HIE the most likely terminal to have these
in the vicinity. Fog returns tonight and may be more widespread
along the coast. Similarly, once it clears Thursday morning,
ceilings will return to VFR with lower ceilings beginning to
approach from the west Thursday evening.

Long Term...A cold front approaches the region Thu night,
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...Wind gusts and seas remain below SCA criteria
through the day Thursday as high pressure remains over the
waters. Winds will be generally southerly through this period
with gusts generally less than 15 kts, increasing to 15-20kts
Thursday afternoon. Expect seas to be generally 2-3ft through
the day Thursday.

Long Term...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...Baron
SHORT TERM...Baron
LONG TERM...Combs/Ekster