Twin Mountain, New Hampshire Weather Forecast Discussion

545
FXUS61 KGYX 230645
AFDGYX
Area Forecast Discussion
National Weather Service Gray ME
245 AM EDT Tue Sep 23 2025
.SYNOPSIS...
A cold front slowly sags south out of Quebec today while
southwest winds will advect warm and humid air into the region
ahead of the front. The approaching front will bring chances for
showers across the north this morning with showers chances
spreading south through the afternoon. The front will stall
across southern New England through Wednesday keeping chances
for showers in the forecast. An area of low pressure will track
across the Northeast Thursday bringing the best chance for a
widespread soaking rainfall followed by a drying trend into the
weekend.
&&
.NEAR TERM /THROUGH TODAY/...
Impacts and Key Messages:
* No significant weather impacts are expected.
Showers have remained north of our area overnight, but they
should begin to sink southward into northern zones toward
daybreak. These will be light as we lack significant forcing to
really squeeze the full potential of the 1.25 to 1.50 PWATs out.
These light showers will continue to sink southward with the
front, making it to the foothills by the early afternoon, and
then spreading across southern New Hampshire and southern Maine
as the afternoon progresses. Before clouds and showers reach
these areas, the 00Z HREF and bufkit soundings suggest we build
a couple hundred J/kg of tall skinny CAPE. This may lead to a
few rumbles of thunder, mainly in southern New Hampshire. The
00Z HREF mean suggests daytime totals range from around a tenth
up to 0.25", with higher amounts nearing a half inch in southern
New Hampshire. Clouds and showers will limit high temperatures
north of the mountains to the upper 60s and low 70s, with
locations south of the mountains seeing more sun into the
afternoon and pushing into the mid to upper 70s. Southeastern
New Hampshire and the southern Maine coast may reach 80F.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
Impacts and Key Messages:
* No significant weather impacts are expected.
Tonight: The frontal boundary will continue to push southward
tonight with multiple waves of low pressure continuing to ride
along it. The latest hi-res models seem to hinting at some
enhanced rainfall as an area of convergence sets up somewhere
near the New Hampshire-Massachusetts border. The 00Z run of the
HRRR keeps this axis of heavier rain south of the border, where
as the 00Z NamNest is right on the boarder with some higher
amounts in far southern New Hampshire. While the location of the
axis of heavier rain is still somewhat uncertain, the models
have been dancing around this area the last few runs which gives
me some confidence that locations in southern New Hampshire
have the higher chances of seeing a soaking rain during the
first part of the night. With lingering instability and warm air
advection in this area, it is not out of the realm of
possibility for some isolated thunderstorms to develop, that may
contribute to higher amounts as well. The 00Z HREF mean
suggests areas south of Concord into the southern tip of York
County get pushed over the half inch to 1 inch mark with these
showers. The PWATs will be trending downward but they will still
be up around 1.50 to 1.75 inches, so if we use the HREF 90th
percentile as a gauge for high end amounts in convection, some
localized amounts up to 1.25 inches are entirely possible.
Beneficial rain for sure, but not a drought buster by any means.
The bulk of the showers then push off the coast, during the
second half of the night with some light showers lingering into
the early morning. Clouds and precipitation keep lows mild (in
the 50s) again tonight, with clouds also limiting fog
development.
Wednesday: Shortwave ridging builds into the region Wednesday,
along with drier air behind the front. This will act to further
limit shower activity during the day. Skies look to clear a bit
in far northern zones during the afternoon as high pressure
briefly noses in. The rest of the area remains under the
influence of low pressure and cloudy skies. This looks to make
for a pretty uniform high temperature spread, with mid to upper
60s areawide. Continued warm air advection will continue the
chance for light showers, but expect any lingering showers to
only add another few hundredths to maybe a tenth of an inch to
totals. Also of note, long period swell arriving from TC
Gabrielle looks to be right on the edge of a high surf advisory
(5ft at 10 seconds) and may pose a moderate to high rip current
risk. Will let the day shift take another look, but being that
it`s late in the beach season and it is marginal, I will forego
advisories at this time, but folks should use caution around the
water regardless.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
01Z NBM Update...No significant changes noted in the latest NBM
through the long term period. The main focus will be the next
shot of widespread rain Thursday into Friday morning. Ensembles
have slightly trended higher for QPF and NBM bringing around 0.5
to 0.75 inches along and south of the mountains from Thursday
morning into Friday morning.
Previously...
Key Message: Finally some chances for rain thru the end of the week.
The rain will be welcomed but do little to alleviate drought.
Impacts: No significant weather impacts anticipated beyond
maintaining/deepening drought conditions.
Forecast Details:
Northwestern Atlantic ridging builds back quickly Wednesday
night as large upper low over the Midwest lifts into the Great
Lakes. This WAA pattern will keep temps running near to above
normal...but also keep the threat of showers in the forecast due
to diurnal heating.
The strongest push of WAA will occur on Thu...and that may bring
another round of light wetting rain. Ensemble guidance is a little
more spread with this event...but similar to Tue into Wed...the 90th
percentile rainfall is about a half inch and a mean around 0.20
inches. It will not be enough to break the drought by any
means...but it will be welcomed rainfall nonetheless.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Short Term...After fog dissipates early this morning we should
see VFR conditions for the remainder of the morning before an
MVFR deck and showers move into the area this afternoon.
Isolated thunderstorms are possible this afternoon and evening.
IFR low stratus decks are possible at some coastal terminals tonight,
but fog development should be limited with the increased cloud
cover. This may result in not much improvement in ceilings past
MVFR for Wednesday with showers continuing to linger.
Long Term...There will be a period from Wed night into Thu
where precip and marine influence will lead to lower CIGs. Aside
from local MVFR or lower in SHRA/RA...there may also be an area
of marine fog/stratus that develops Wed night and moves
southwestward down the coast. Coastal terminals could see IFR or
lower conditions thru Wed night...especially from PWM south.
Conditions improve Friday as drier air begins to work into the
area.
&&
.MARINE...
Short Term...Swell from TC Gabrielle continues to build today,
with seas reaching 5ft and remaining there through at least the
day Wednesday. Winds gusts remain below 25kts. Southwesterly
winds will shift northerly overnight as a front crosses the
waters. Winds will continue to shift around to almost due
westerly by the end of the day Wednesday.
Long Term...Swell from Gabrielle may linger into the second
half of the work week. Areas of fog may develop Wed night and
linger into Thu ahead of frontal systems moving thru the region.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory from 2 AM Tuesday to 8 PM EDT Wednesday
 for ANZ150-154.
&&
$$
NEAR/SHORT TERM...Baron
LONG TERM...Legro/Schroeter

NWS GYX Office Area Forecast Discussion