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198
FXUS61 KGYX 130021
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
821 PM EDT Sat Jul 12 2025

.SYNOPSIS...
An airmass with high humidity over the area will linger into
Sunday. Look for a chance of a few showers or a thunderstorm
during peak heating tonight. A cold front will near the region
on Monday with widespread showers and thunderstorms, some of
which could produce locally heavy rainfall. Drier weather
returns Tuesday, with heat and humidity building in for the rest
of the week.

&&

.NEAR TERM /UNTIL 7 AM SUNDAY MORNING/...
-- Changed Discussion --
820 PM Update...Shower and storm activity has diminished after
flash flooding was observed earlier this evening across western
Hillsborough County. Recent runs of the HRRR suggest isolated
showers cannot be ruled out across central NH through interior
western Maine through tonight. Otherwise visibilities will be on
the downward trend as fog becomes more prevalent, especially
near the coast.

Previously...

Stagnant pattern with weak onshore flow continues to keep
stratus over the coast through the foothills today and tonight.
There will be some breaks of sun through mid to late afternoon,
but expect overnight conditions to again thicken and lower with
fog redeveloping.

To points north of the mountains, a mostly sunny day is underway
with the warmest temps in the forecast area. Shower and storm
activity is still expected this afternoon and early afternoon,
boosted by daytime heating in mostly sunny areas. With no
prominent lifting feature, showers/storms may anchor themselves
on terrain initially, before drifting in weak steering flow.
Based on morning showers that went through southern ME, these
slower moving cells will have the capability to reach 1 to 2
inch per hour rainfall rates. Combined with their slow motion,
localized lowland flooding will be possible through the evening.

In contrast to the previous nights, MUCAPE dwindles over the CWA
tonight. This should limit coverage of showers to this evening
with activity remaining west and NW of the area.

Fog builds down later tonight. Would expect dense fog to limit
visibility for the coast, interior, and foothills once again.
-- End Changed Discussion --

&&

.SHORT TERM /7 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
Sunday begins similar to Saturday with low stratus and fog in
place. Points north and west of the mountains see the best
chance at sun for the morning, but again will see afternoon
showers and some thunder develop. CAMs portray less shower
coverage for the daytime before forcing increases Sunday night.

Overnight, a cold front will advance east from the Great Lakes.
Associated warm front was forecast to push through the CWA
overnight, but has since weakened on eastward extent. Thus
concentration of precip will remain west with just a few showers
or storms passing through overnight.

Increasing clouds and the passing warm front may favor a mild
night. The CT Valley and southern NH may retain some daytime
heat with overnight lows in the upper 60s to around 70.

Otherwise, the day/night trend of fog moving in overnight
continues for another day.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Key Messages


 - Flash flood risk Monday with frontal passage

 - Steamy hot/hazy summer days starting Tuesday

 - Mainly hit/miss (30%) thunderstorm chances mid-late week

Monday will start off with a cold front approaching from the north.
This feature combined with weak but sufficient dynamics will touch
off scattered showers and thunderstorms, higher chances near the
international border, and mainly after 17Z. Generally looking at
weak dynamics with SBCAPE ~600 and bulk shear 10-20 knots.
PWAT values >1.75" (2 standard deviations above normal) with the
potential for pooling ahead of the front pushing PWATs to 2".
This will make for more concerns over heavy-rainers than for
severe weather. The relatively weak flow suggests some slow-
moving storms, and the corfidi vectors favor regenerative
propagation and set-up for training. WPC has much of the area
outlooked in a marginal for Monday, despite models not depicting
much QPF at this time. Believe there could be local amounts of
2-3", but if the pattern holds I wouldn`t be surprised to see
upwards of 4" on a very localized basis. We`ll continue to
highlight heavy rain potential in the grids and in our Hazardous
Weather Outlook.

Once the frontal passage clear the area there will be a brief drop
in humidity going into Tuesday. Looking a plentiful sunshine which
will allow temps to rise into the upper 80s to low 90s for most
areas. The expansion of the summertime upper ridge and the Bermuda
high will dominate the weather across much of the east coast for
much of the work week. This pattern will favor a return to
summertime hot and hazy days. A progressive zonal flow regime late
week will likely bring scattered showers and thunderstorms, but
timing of these weak features is difficult this far out. Have stuck
with the typical diurnal risk windows in the afternoon until
conditions become clearer. Overall, Tuesday looks to be the best
chances for dry weather, while Friday could see the more widespread
showers and storms as another surface cool front approaches.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Short Term...Some breaks in the clouds will offer a window of
MVFR to VFR conditions along the coast this afternoon. SHRA and
TSRA develop mainly along the western and northwestern borders
this afternoon and evening. Overnight, a return to IFR and LIFR
is expected for most terminals along the coast and interior.
Sunday begins similar with a slow improvement in vis before
ceilings break even slower. Coastal terminals may remain IFR for
an extended period. Less SHRA coverage Sunday and Sunday night.

Long Term...Stratus/fog possible again on Sunday night into early
Monday, however an approaching cold front will limit the extent and
duration. Heavy rain with IFR conditions possible with scattered
showers Monday, then improving to VFR under sunny skies Tuesday.
Mainly VFR thereafter.

&&

.MARINE...
Short Term...Below SCA conditions as onshore flow continues.
Expect marine stratus and fog to continue over the coastal
waters, limiting visibility at times.

Long Term...Expect similar to above through much of the work week.
Winds with the initial cold front Monday night washout out so apart
from light and variable there are no notable wind shifts. Looking at
predominant S/SW/SE winds throughout the forecast, with waves 2`
with a 7-8 sec swell.

&&

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

&&

$$


NEAR TERM...Cornwell/Schroeter
SHORT TERM...Cornwell
LONG TERM...Jamison