931
FXUS61 KGYX 171819
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
219 PM EDT Sun Aug 17 2025

.SYNOPSIS...
A cold front will bring a round of showers and a few
thunderstorms today, followed by cooler weather for the start of
the work week. A weak trough will trigger some showers
Wednesday, followed by high pressure building in from the west.
Temperatures will warm back into the 80s by late week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Impacts and Key Messages:
* A few strong to marginally severe thunderstorms are expected
  this afternoon and evening, with strong winds being the main
  threat.

Things seem to be on track this afternoon as showers are
starting to cross into our area from across the International
Border, with no lightning yet. This was expected as early clouds
kept temperatures and instability lower up there. Storms are
beginning to PoP up in the vicinity of the White Mountains and
points south. Also, no lightning yet at the time of this
writing, but as they move into the hot and humid airmass near
the coast they should be able to rise quickly. SPC mesoanalysis
suggests we have been able to build up 1000-1500 J/kg of SBCAPE
this afternoon south of the mountains which will be plenty for
storms to feed off of. At the same time mid-level lapse rates
are analyzed to be poor (around 5.5 C/km) which suggest more
isolated coverage, but low level lapse rates are steep (near 8.5
C/km) so any of the more robust convection that is able to get
going will pose a strong wind threat. Precipitation remains hit
or miss for much of the area south of the mountains and west of
Augusta, with the 12Z HREF mean suggesting zero to a tenth of an
inch and the max suggesting a sporadic 0.25-0.50 for any one
lucky enough to get under a more robust storm. Again, there will
likely be more than a few locations that miss out completely
this evening. In central Maine and the Midcoast, where models
have been consistently putting more robust convection, the HREF
mean is in the ballpark of 0.50-0.75, with the max suggesting
getting under the core of a good storm could net a location up
to 1.50-2", but again these are isolated amounts. By the 7-8PM
window showers and storms should be either departing off the
coast or losing their fuel.

Cooler and drier air quickly follows behind the front allowing
for temperatures to plummet up north, to around 40F. The front
will continue to slowly sink south with the foothills dropping
to the upper 40s and around 50F, and the coastal plain more in
the mid- to upper 50s. This quick entrance of the high will
tighten the pressure gradient behind the front so many locations
probably see breezy winds (15-20mph) most of the night, maybe
closer to 25mph along the immediate coast. This should stave off
any fog as well.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
Impacts and Key Messages:
* No significant weather impacts expected.

High pressure builds back into the region with 500mb heights
rising as well, as the trough continues out to sea. The cold
frontal passage will have ushered in cooler and drier air,
making for a welcomed pattern change, at least on the
temperature front. High temperatures are going to give us an
early taste of Fall as they only climb into the low to mid-70s
south of the mountains, and into the upper 60s and low 70s to
the north. The unfortunate aspect is that clear skies mean we
will continue to see drying across the area and likely expansion
of drought conditions, especially in areas that miss out on
rain today (Sunday). Winds gusts 15-20mph may continue into the
morning, mainly in the coastal plain, but high pressure builds
in quickly, so would expect them to slacken by the afternoon.

Calm winds and clear skies should allow for a very cool night
areawide. There is some suggestion that low pressure will be
slowly approaching from the Great Lakes Region overnight Monday
causing some subtle height falls and streaming some clouds into
the region late in the period (more toward sunrise Tuesday).
Whether clouds actually make it or not, I think there is plenty
of time for some radiational cooling to occur and blended in
some MAV guidance to overnight temperatures. This brings low
temperatures into the 40s pretty much areawide, with maybe some
coastal locations holding near 50F.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Key messages

-Overall trend favors below normal temperatures and rainfall
 for much of the extended.
-Warming trend for late week into the weekend

Looking at a cold start on Tuesday with many locations in the
40s, and with light winds we can expect steam fog over inland
water bodies. High pressure will dominate on Tuesday with just a
few fair wx cumulus clouds. Return flow out of the S will try
to bring in some moisture, but daytime mixing will counteract
much of it keeping dewpoints <50F. Clouds drift in Tuesday night
as a shortwave swings across the area. This feature will have
dynamics to support scattered showers, but models are starting
to recognize the moisture-starved airmass ahead of it and have
backed off on both POPs and QPF. Most areas will be lucky to get
0.1" out of this system, with best probs in the north. Cloud
cover will keep temps a few degrees cooler on Wednesday, with
60s to low 70s for most areas. Mainly dry conditions are
expected Wed night through Fri as high pressure slides east.
Ridging aloft will support warming temperatures for both Fri and
Sat, with highs in the 80s returning. The next chance for rain
is likely to be associated with a cold front Sunday, but low
confidence on coverage at this point.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Short Term...Showers and thunderstorms move through this
afternoon and evening. AUG and RKD are the most likely to see
lighting in the vicinity and that has been included in the TAF
accordingly. Otherwise, run of the mill showers should not cause
any issues. Winds will be breezy tonight with all terminals
likely to see gusts up to 15kts at times and coastal terminals
like PWM could see gusts up to 20kts. Wind gusts will begin to
relax Monday morning with VFR ceilings prevailing.

Long Term...There will be localized river valley fog through
the first part of next week that will cause localized
reductions, especially across the northern terminals. Otherwise,
large area of Canadian-sourced high pressure will expand across
the region providing widespread VFR conditions through the
entire TAF period.

&&

.MARINE...
Short Term...Showers and thunderstorms are possible as a cold
front approaches the waters this evening. A brief period of
northerly wind gusts 25-30 kts is possible overnight tonight
into early Monday morning behind a cold front moving over the
waters.

Long Term...The long term will start with N/NE winds at 10 kt
N/NE and >3 ft seas. Conditions will gradually deteriorate as
long period swell from Erin makes its way to the Gulf of Maine.
Looking at long period swells of 12-15 sec reaching the area
Wednesday, growing to 17-20 sec Thu into Fri. Wave heights will
peak on Friday with SCA conditions likely with seas >5` for much
of the coastal area. High rip current threat all but
guaranteed, and a good chance for high surf conditions for at
least the Midcoast. Winds during this time will be <10kt with
predominantly offshore flow.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory from 11 PM this evening to 10 AM EDT
     Monday for ANZ150-152-154.

&&

$$

SYNOPSIS...Jamison
NEAR/SHORT TERM...Baron
LONG TERM...Jamison