557
FXUS61 KGYX 262355 AAA
AFDGYX

Area Forecast Discussion...UPDATED
National Weather Service Gray ME
755 PM EDT Sat Jul 26 2025

.SYNOPSIS...
Smoke and haze from Canadian wildfires continue through
this evening, but otherwise the rest of today remains warm with
lower humidity. High pressure shuffles east as the next system
moves in Sunday with chances of showers and storms, especially
across southern NH. Heat and humidity begin to build again early
next week.

&&

.NEAR TERM /THROUGH SUNDAY/...
8pm Update: Quick update to drop the beach hazards statement for
the Midcoast region and also to extend the haze mention through
the remainder of the evening per visible satellite...
webcams...and latest smoke forecasts from the HRRR. Otherwise no
changes to the forecast as temperatures slowly settle back from
afternoon highs with a dry profile overhead as per 26.00Z GYX
RAOB.

Previous Discussion Below...

High pressure that is currently overhead will provide a warm
and dry rest of the day today with humidity levels remaining
comfortable as we mix down dry air aloft to keep dewpoints in
the 40s and 50s. We`re starting to get some high clouds across
western areas, and it may also remain hazy into early this
evening as northwest flow aloft brings in Canadian wildfire
smoke. The high will steadily shift to the east through tonight
and give way to an approaching shortwave trough. Clouds will
increase through tonight, which is expected to both keep temps a
little milder than this morning and also largely prevent fog
from developing. Forecast lows are mostly in the 60s, but far
northern and eastern areas still could cool into the 50s with
lesser/thinner cloud cover. A vort max associated with the
incoming shortwave may start bringing showers into SW NH as we
approach daybreak, but I think most of these will hold off until
after.

&&

.SHORT TERM /SUNDAY NIGHT/...
Chances for showers and a few thunderstorms will increase through
the morning and afternoon on Sunday as the 500mb shortwave crosses.
Guidance continues to favor the southern half of NH and into far
southwest ME for the higher of the precip chance with even better
chances for SW NH. Increasing PWATS and a deep warm cloud layer
suggest some of the showers and storms could contain heavy
downpours with the latest HREF suggesting localized amounts of
1-1.5" rain possible across SW NH. Storms are not expected to be
strong or severe with limited instability and it being mostly
remaining elevated. These areas should see a decrease in chances
later in the afternoon once the wave passes, but some degree of
redevelopment is possible. Farther to the north and east,
chances for precip decrease as the air will be drier and more
subsident, but a secondary shortwave dropping to the south and
east in Canada still may bring a few showers and storms in the
afternoon and evening.

Clouds and more precip will likely keep southern areas cooler and in
the 70s, but less clouds to the north and east will probably still
allow temps to reach the lower 80s.

Mostly dry conditions are expected Sunday night, but a moist
boundary layer and little to no low-level flow will allow for fog
development in some areas, especially those that see rain on Sunday.
Lows will be in the upper 50s to low 60s.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Overview: Warm and humid conditions will prevail early next week
with scattered showers and thunderstorms, especially during the
afternoon hours. Cooler weather will then arrive by the middle to
end of the week through the upcoming weekend with mainly dry
conditions.

Impacts: Afternoon heat index values could reach the 95-100F
range across portions of south-central NH and southwestern ME
Monday and Tuesday. Otherwise, confidence is low for any
hazardous weather at this time.

Forecast Details: Monday will feature warm and humid conditions as
H5 ridging builds overhead with sfc high pressure to our southwest.
High temperatures will range from the upper 80s/lower 90s for
interior locations with upper 70s/lower 80s along the coast due to
onshore flow. A few afternoon showers and thunderstorms are possible
as a weak stationary boundary remains in the region. A weak wave of
energy may cross Monday night, allowing for a continued chance for
scattered showers with the greatest potential of rain across the far
north and mountains. Lows will be primarily into the 60s.

Warm and humid conditions will persist on Tuesday ahead of a sfc
cold front that will be approaching from the north. Ahead of this
front, highs will soar into the lower to middle 90s south of
the mountains with heat indices approaching 95-100F. Scattered
showers and thunderstorms are possible, some of which may
contain gusty winds. Lows will once again be mainly into the
60s. A secondary cold front will likely cross on Wednesday with
scattered showers and rumbles of thunder under partly cloudy
skies. A large temperature range is likely with readings ranging
from the 70s across the north to near 90 in southern NH. Cooler
air will begin to filter in on Wednesday night with lows into
the 50s/60s.

The rest of the week and the upcoming weekend will feature cooler
temperatures as troughing develops over the Northeast. Other than a
few scattered showers at times, much of the period will be dry.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Short Term /through Monday/...

Summary: A trough will push through the region on Sunday
bringing deteriorating conditions and a chance of showers and an
embedded thunderstorm. High pressure and improving conditions
arrive for Monday.

Restrictions:  VFR conditions through tonight...with deterioration
to MVFR south of HIE from west to east on Sunday as clouds lower
with showers and embedded thunderstorms possible.  Any shower/storm
activity will end by mid/late afternoon. Skies clear Sunday
night...with overnight fog possible throughout the region.

Winds: Winds currently diminishing to 5kts or less for the overnight
before shifting southerly 10g15kts for the day Sunday.  Winds again
diminish to 5kts or less Sunday night before shifting northwest 5-
10kts for the day Monday with afternoon seabreezes PSM/PWM/RKD.

LLWS: 1-1.5kft southwesterlies increase to 20kts overnight...a bit
short of LLWS criteria.  This llevel shear will end quickly Sunday
morning as mixing commences with no LLWS expected through Monday.

Lightning: There is some potential for thunder for LEB/CON/MHT/PSM
by late Sunday morning through mid afternoon.  No thunder is
expected beyond this through Monday.

Long Term...Mainly VFR conditions are expected through the
period outside of any scattered SHRA/TSRA. Some valley FG and
marine FG may develop mid-late week as well, possibly bringing
localized restrictions.

&&

.MARINE...
Short Term...SCA conditions are not expected through Sunday
night. High pressure will shift east of the waters tonight with
south to southwest flow prevailing ahead of a weak low pressure
and front that will bring showers and few storms to the waters
Sunday morning and afternoon, primarily south of Casco Bay. The
weak front crosses sometime Sunday night, and winds may shift
briefly to more westerly.

Long Term...Winds and seas to remain below SCA criteria through
the period as a series of weak fronts move near or across the
waters.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Air Quality Alert until 11 PM EDT this evening for MEZ007>009-
     012>014-018>028-033.
NH...Air Quality Alert until 11 PM EDT this evening for NHZ001>015.
MARINE...None.

&&

$$

NEAR TERM UPDATE...Arnott
AVIATION UPDATE...Arnott