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566
FXUS61 KGYX 301750
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
150 PM EDT Mon Jun 30 2025

.SYNOPSIS...
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High pressure moves east of New England today, bringing mostly
dry conditions and a warming trend, as well as increased
humidity. Low pressure tracking through Quebec will drag a cold
front across the area Tuesday bringing chances for
thunderstorms, a few of which may be strong to severe. Outside
of some mountain showers and a chance of showers and storms on
Thursday, generally dry conditions are expected from Wednesday
through Saturday.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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Impacts and Key Messages:
* No significant impacts expected

At this hour some high clouds are just starting to a enter into
southwestern New Hampshire. Current temperatures are in the
upper 70s to around 80 across the area and we still have a few
more hours of good warming before things begin to level off.
Cloud cover thickening from southwest to northeast will be the
trend through tonight which will keep low temperatures in the
mid to upper 60s in southwestern New Hampshire (the first to see
thicker clouds move in) and lower 60s in northern New Hampshire
and western Maine where it will stay clearer longer. Showers
move in after midnight and may even contain some rumbles of
thunder as the warm front advances into the region toward
sunrise. Even some of these early showers/storms may be capable
of producing downpours and gusty winds.
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&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
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Impacts and Key Messages:
* Strong to severe thunderstorms are possible Tuesday. The
  stronger storms may produce damaging wind gusts.
* These storms will also be capable of producing heavy rain.
  Isolated flash flooding is possible in locations that see
  repeated rounds of storms.

Tuesday`s severe weather threat looks very conditional as
ongoing showers and storms during the morning hours will
contribute to cloud debris that could inhibit the development of
much instability ahead of the front. Latest Hi-Res Ensemble
Forecast guidance shows the best forcing from the front crossing
in the late afternoon early evening. This only leaves a small
window for instability to build if any areas can break out into
some clearer skies. With a moist airmass in place (dewpoints in
the upper 60s to low 70s) and shear around 30 kts, the
environment will be primed provided we can get the CAPE.
Ensemble guidance continues to suggest that even with a
shortened window, around 1500 J/kg of CAPE could develop which
would be plenty to achieve some robust convection. It wouldn`t
be a GYX severe weather discussion if I didn`t mention our poor
lapse rates, only around 5.5 C/km, this may also work to limit
coverage and keep storms sub-severe. The other threat we will
have to watch is the possibility of some isolated flash flooding
as PWATs climb to around 2 inches over the Northeast. It is
hard to say if I have any more confidence in this threat as I
feel like it would also take some more robust convection (it
won`t have to be severe) to actually cause issues, and with
progressive storm motions it would take repeated rounds over a
location as well, which with limited coverage of storms would be
harder to materialize. I don`t want to sound like I am
downplaying any threats, as any severe storms would be capable
of producing damaging wind gusts and the environment is primed
for very efficient rainfall rates, but it should be noted there
is quite a bit of bust potential as well.

Any severe threat looks to pass not long after sunset as storms
will quickly lose their fuel. Despite clear skies and light
winds, elevated dewpoints will keep low temperatures from
dropping much past the low to mid 60s, with southern New
Hampshire maybe even staying pretty close to 70.
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&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
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Wednesday will be a warm and drier day as Tuesday`s frontal
system will be east of the area, taking the deep moisture along
with it. There still may be enough moisture in the mountains for
a few showers early in the day with a weak wave aloft and
upslope flow, but otherwise, partly sunny skies are expected
with temperatures mostly in the 80s.

An upper low then drops southward into Quebec on Thursday,
which will send another cold front through and bring another
chance of showers and storms. Depending on the time of day, some
of the storms could be strong away from the coast as deep layer
shear is modeled to be around 35 to 40 kt. Temperature will
again be warm and mostly in the 80s. Those that receive rain
during the day Thursday may see fog develop overnight as flow
will be light.

The upper low will slowly move eastward across or just north of
the area on Friday, and even though Thursday`s front will be
east of us by then, enough lift/moisture from the upper low will
bring a chance of showers and maybe a couple of storms, mainly
across northern and eastern areas. Instability and shear
parameters do not look favorable for strong storms at this time.
Western and southern areas are expected to remain dry as
heights begin to rise and subsidence increases. Temperatures
come down slightly with mid 70s to low 80s.

Dry conditions are expected on Saturday with increasing
subsidence and further heights rises as a 500mb ridge works into
New England. There is then a general consensus in the global
models in a low pressure passing well to the north Sunday into
Monday and dragging a frontal boundary toward or into New
England. The GFS breaks the ridge down much faster and increases
rain chances as early as Saturday night while the ECMWF holds
the ridge and dry weather through Sunday. However, the ensembles
favor the unsettled pattern/higher rain chances from Sunday
into early next week, which is supported in the increasing PoPs
from the NBM Sunday into next Monday.
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&&

.AVIATION /17Z MONDAY THROUGH FRIDAY/...
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Short Term...Increasing moisture will aid in the development of
areas of fog at valley and coastal terminals tonight. This
likely brings about IFR/LIFR conditions until it mixes out. It
may not be too quick to mix out as passing showers and a few
thunderstorms early on Tuesday morning would help to lock in
lower ceilings until mid morning or so with western terminals
clearing first and coastal terminals clearing last. A renewed
chance of thunderstorms and therefore brief restrictions, comes
about late Tuesday afternoon for western terminals and closer to
00Z for coastal terminals. A brief period of fog and/or low
stratus is possible in the immediate wake of showers and storms
late on Tuesday, but a frontal boundary will sweep through
improving conditions to VFR overnight.

Long Term...Mainly VFR Wednesday through Saturday. Afternoon
showers and storms Thursday may produce localized TEMPO IFR TO
MVFR restrictions with the highest chances away from the coast.
Fog then may develop Thursday night in areas that receive rain.
Chances for showers/storms are lower on Friday but still could
see a few near LEB-HIE and AUG-RKD.
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&&

.MARINE...
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Short Term...SCA conditions are not expected through Tuesday
morning as high pressure moves over the waters. A frontal
boundary then crosses the waters Tuesday night which may create
a brief period of wind gusts up to 25ft and seas up to 5ft in
the outer waters. These elevated wind gusts and seas will
quickly subside overnight behind the front.

Long Term...Weak low pressure/front crosses the waters Wednesday into
Thursday, but SCA conditions are not expected. Conditions remain
below SCA levels Friday into Saturday with broad high pressure in
control. A low pressure passes well to the north Sunday into Monday
of next week, and winds/seas may increase to SCA levels during this
time as a frontal boundary approaches New England.
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&&

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

&&

$$


NEAR/SHORT TERM...Baron
LONG TERM...Combs