Area Forecast Discussion
Issued by NWS Portland, ME

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628
FXUS61 KGYX 170547
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
147 AM EDT Fri Oct 17 2025

.SYNOPSIS...
Low pressure south of Nova Scotia loosens its grip on the
region today as it drifts east and high pressure builds in from
the west. High pressure settles south of New England Saturday
and moves east Sunday in response to trough swinging through the
Great Lakes. This trough will send a frontal system into New
England Sunday night and Monday bringing chances for some
beneficial rain. Troughing lingers over the Northeast through
the middle of next week with additional chances for showers.

&&

.NEAR TERM /TODAY/...
At the upper levels, a low continues to spin out over the ocean
with a ridge axis located to our west over the Midwest. High
pressure will start to move into the region at the surface
through the day but the pressure gradient will remain fairly
tight through the morning and early afternoon, leading to more
breezy winds out of the north and diminishing cloud cover.
Additionally, there could be some patchy frost this morning,
especially across our western zones where winds are quicker to
diminish.

Today will be a touch warmer than yesterday with highs mainly in
the lower 50s to lower 60s. A few readings in the 40s are likely
across the mountains.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
Winds will diminish tonight and we should have clear skies so
conditions should be ripe for radiational cooling. For lows
tonight, utilized a blend of NBM and the NBM 10th percentile to
nudge temperatures a bit closer to what we expect. Forecast lows
will range from the low to mid 20s north and across the
mountains, to the low/mid 30s south and a long the coast. With
the light winds, widespread frost is likely overnight. In
coordination with the neighbors, will hold off on any headline
decisions for now, but frost/freeze products may be needed
tonight for some southern New Hampshire and interior zones.

The ridge axis moves overhead on Saturday, leading to another
slight warmup and plenty of sunshine with highs mainly ranging
from the mid 50s to the mid 60s. We should start to see some
increasing cloud cover across New Hampshire during the later
afternoon hours but the forecast will remain dry.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
01Z NBM Update...No significant changes noted in the latest NBM
other than a slight increase in PoPs Sunday night into Monday
and Tuesday night into Wednesday. There is a spread amongst
ensembles with respect to QPF Sunday night into Monday with
the GEFS mean QPF around 0.25 to 0.5 inches and the ECMWF/CMC
ensembles around 0.75 inches with higher amounts in the
mountains. Overall looks like some beneficial rain by Monday
evening. Unsettled conditions likely persist into the middle of
the week with another possible frontal system crossing around
Wednesday.

Previously...

Pattern Overview: A ridge moves east Sunday for continued mostly
dry weather and above normal temperatures. The pattern then
becomes increasingly unsettled as multiple upper level lows look
to pass through the region next week.

Impacts and Key Messages:
* Temperatures trend above normal through the weekend
* The pattern becomes increasingly unsettled next week with
  multiple disturbances to keep an eye on

Details:

Sunday and Monday: The ridge axis shifts eastward over the Gulf
of Maine Sunday increasing the southwesterly flow aloft and
warming 850mb temperatures to around +11C. This looks to be the
warmest day with temperatures south of the mountains able to
climb into the mid- to upper 60s, and into the low to mid 60s to
the north under mostly clear skies. Clouds build in during the
evening and overnight as a potent trough approaches the region.
This keeps Sunday night mild with lows only able to fall into
the 40s areawide, with the coastline hovering around 50F. Models
have come into slightly better agreement regarding timing of
the front Monday, but the positioning of the low is still up in
the air as the Euro continues to cut off the low over the Mid
Atlantic, while the GFS has an inside runner that whips off to
the northeast. The GFS solution is faster and drier with
ensemble probabilities of greater than a half inch less than
30%. The Euro solution would result in a more prolonged event
with probabilities greater than a half inch in the 30-50% range.


Tuesday-Thursday: The main difference in the above solutions
mainly effects Tuesday`s outcome. As mentioned the GFS solution
is in and out on Monday making for a mostly dry Tuesday. The
Euro has the low crawling eastward continuing showers through
the day Tuesday. The QPF looks light and largely inconsequential
if the Euro ends up correct, but the difference between a dry
day and light showers is, so this will have to be watched. There
is decent agreement in another upper low swinging in right
behind this one midweek and taking the southern/coastal track.
This one being at the end of the forecast period means there is
plenty of time for further developments, but an early look at
ensemble probabilities for the Wednesday-Thursday period suggest
another round of mostly light showers with probabilities of
greater than a half inch less than 30% in both suites.
Stretching this out to look at the probability of greater than
an inch accumulating from both events yields a 40-60% chance
from the Euro ensemble suite and 20-40% for the GFS suite. As
has been said many times over the past few months, beneficial
rain may be on the way, but it won`t be a drought buster.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Short Term...AUG and RKD continue to see MVFR ceilings holding
on early this morning, but we should start to see improvement
here over the next few hours as the stratus deck continues to
erode to the east. Otherwise, VFR conditions should prevail
through at least Saturday. Some patchy fog will be possible
across the valleys and coastal areas Saturday night.

Long Term...VFR likely prevails Sunday before ceilings begin to
thicken and lower after 00Z Monday. Monday could be a mix of
MVFR and potentially lower conditions as showers move through
the region. This may result in fog Monday night if the showers
come to an end. Tuesday may also feature some showers, but even
if it does not, ceilings likely remain largely MVFR.

&&

.MARINE...
Short Term...Gusty north northwest winds should continue through
the morning. Marginal gales outside of the bays will transition
to SCAs at some point early this morning. SCA conditions will
also linger in the bays this morning. High pressure builds in
later today and winds/seas will continue to gradually diminish.

Long Term...Winds and seas will be below SCA thresholds Sunday.
Southerly winds increase Sunday night into Monday along with
building seas ahead of a cold front. SCAs will likely be need
for winds and seas during this time period. Winds drop below SCA
thresholds Monday night while elevated seas may necessitate SCAs
into Tuesday.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Gale Warning until 8 AM EDT Friday for ANZ150-152-154.
     Small Craft Advisory until 8 AM EDT Friday for ANZ151-153.

&&

$$


NEAR TERM...Hargrove
SHORT TERM...Hargrove
LONG TERM...Baron/Schroeter