917
FXUS61 KGYX 110757
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
357 AM EDT Mon Aug 11 2025

.SYNOPSIS...
High pressure remains in control for the next few days, and
temperatures continue to rise through the first half of this
week as a ridge of high pressure builds over the Northeast. The
ridge starts to break down mid week and that will allow for some
chances of showers and thunderstorms as a cold front
approaches. The weekend looks to be dry at this time with a
warming trend possible by Sunday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

355AM Update...Just resending to add a climate section as
forecast temperatures could threaten daily record highs today
through Wednesday.

Previous...

There will be patchy fog in some areas this morning,
especiallthreateny within river valleys, but once this clears
by 8 to 9 AM, the focus remains on the heat with temperatures
expected to climb even higher than yesterday. A strong ridge of
high pressure builds directly overhead today bringing mostly
sunny, hot and dry conditions. 850mb temps of +18C to +20c
supports highs reaching the lower to mid 90s across much of the
interior today with heat indices likely above 95F for a few
hours this afternoon across the Maine interior/foothills
stretching into southeastern NH, where the Heat Advisory is in
place. Looking back at the past few days, NBM and MAV guidance
have had consistent a cool bias away from the coast, possibly
due to how dry it is. So I`ve played the persistence card on
temps today by going a degree or so above the NBM, but this
doesn`t really change the overall message of it`s going to be
hot regardless. A little more moisture toward the mountains may
result in a shower or two this afternoon but mainly just a tad
more in the way of clouds than southern areas.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Fortunately there will be some relief to the heat tonight.
Mostly clear skies and light winds will allow for radiational
cooling, and since the airmass is not as humid as past heat
events this summer, temperatures will be able to reach the low
to middle 60s for lows, possibly even the upper 50s in some of
the northern valleys. Speaking of valleys, valley fog will
probably develop in many areas and possibly the Augusta and
Midcoast regions as well.

The synoptic patterns remains largely unchanged with strong ridge of
high pressure remaining directly overhead for Tuesday, bringing
nearly identical conditions to those of today: hot and mostly
sunny with only a very low chance of a shower or two in the
mountains. Temperatures away from the coast are expected to
reach the low to mid 90s, possibly even upper 90s in some spots,
with heat index values likely exceeding 95F for a few hours in
many areas, where the Heat Advisory remains. Those not in the
Heat Advisory can still expected heat indices in the 90-95F
range, even closer to the coast before the seabreeze moves
ashore in the afternoon.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Early morning long-term update...

Key messages from the previous shift remain the same through
Wednesday as another hot day is expected. There`s a good chance
that the heat advisory will have to be extended for Wednesday.
The same holds with precipitation chances as the best chance for
at least widely scattered showers and thunderstorms looks to be
during the afternoons Wed and Thu. Widespread rains are not
expected however.

Previously...


Key Messages:
* Heat continues Wednesday with highs in the upper 80s to mid
  90s. A Heat Advisory with continuation into Wednesday likely.
* Cold front approaches Wednesday, decreasing temperatures late
  week.

Details: Continued to increase temperatures Wednesday from the
NBM deterministic. Combination of dry surface conditions and
mostly sunny skies should allow for quick morning warmup to
around 90 for much of the forecast area. From here, highs push
into the low to mid 90s across the interior and even mtn
valleys. Along the coast (especially the Midcoast), light
onshore flow will tend to strengthen in the afternoon,
reinforced by seabreeze. Thus, temps along the coast peak early
afternoon, with a moderating airmass for remainder of the day.

The good news, despite this longer period of heat, is the
relative dryness of the airmass as well as good overnight
recovery temperatures in the 60s. Dewpoint temps will tend to
run low considering dry antecedent surface conditions, but there
won`t be enough momentum transfer to mix down even drier values.
This keeps heat index values close to actual temperatures.

Given the confidence in this airmass, an extension to the Heat
Advisory will likely be needed for Wednesday, but next incoming
cold front offers some uncertainty in cloud cover and possible
showers.

Consensus does keep precipitation largely west of the CWA into
early Wed afternoon, but can expect some clouds ahead. With
building CAPE and forcing, could see some showers and
thunderstorms develop ahead of the main forcing. However, lapse
rates are not steep and shear of around 20 kts could prevent a
more widespread thunder event.

Winds shift NW behind the front Thursday, with a dip in expected
high temperatures late week into the mid to lower 80s.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
Short Term...No change in the weather pattern. Fog will bring
restrictions through early this morning, mainly at LEB, HIE, and
RKD, and then VFR the rest of today. The same sites will likely see
fog again tonight and possibly AUG, but then VFR returns the
remainder of Tuesday.

Long Term...VFR conditions look to prevail, but there will be
the chance for some restrictions due to coastal and valley fog.
This appears most likely during the overnight and early morning
hours. Weak winds in the low levels present little risk of LLWS
development, with wind shifts expected around daily sea breeze
fronts.

&&

.MARINE...
Short Term...Conditions remain below SCA levels across the waters with
prevailing south to southwest winds through Tuesday, backing to the
S/SSE and increasing slightly in the afternoons with the seabreeze.
Seas over the outer waters will run 2-3 ft, occasionally up to 4 ft
today. Fog/stratus will also be possible, especially across the
eastern waters and near Penobscot Bay.

Long Term...High pressure centered to the south will keep
conditions over the waters below SCA criteria. Expect some
marine stratus/fog to develop in warming air temperatures this
week. Onshore flow directions expected for the most part, with
diurnal sea breeze. Wave heights generally remain 2 to 3 ft.

&&

.CLIMATE...
Daily record highs and year(s) set for today, August 11 through Wednesday,
August 13 for Portland, Augusta, and Concord.

          Portland          Augusta       Concord
Aug 11    99F (1944)        94F (2016)    98F (2016, 1944)
Aug 12    99F (2016, 1944)  93F (2002)    99F (2016, 1944)
Aug 13    99F (1947)        94F (2004)    99F (1944)

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Heat Advisory from 11 AM this morning to 8 PM EDT Tuesday for
     MEZ012>014-018>022-033.
NH...Heat Advisory from 11 AM this morning to 8 PM EDT Tuesday for
     NHZ010-012-013.
MARINE...None.

&&

$$

NEAR TERM...Combs
SHORT TERM...Combs
LONG TERM...Cornwell/Ekster