Sandown, New Hampshire Weather Forecast Discussion

487
FXUS61 KGYX 042230
AFDGYX
Area Forecast Discussion
National Weather Service Gray ME
630 PM EDT Thu Sep 4 2025
.SYNOPSIS...
A trough swinging into the Great Lakes will send a cold front
towards New England, bringing increasing chances for showers
tonight into early Friday morning. Another front approaches for
Saturday perhaps allowing for more substantial rainfall and
thunderstorms over a wider area. High pressure moves in early
next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
625 PM Update...Little change to the going forecast. Diurnal CU
will gradually dissipate allowing for a mostly clear evening. A
cold front will approach from the west with showers entering the
CT River Valley region just prior to midnight. An isolated
thunderstorm is possible as well.
Previously...
Seasonably warm and dry conditions continue this afternoon with
shortwave ridging in place across New England. A tightening gradient
ahead of an approaching cold front will support wind gusts of 20-25
mph at times will make for increased fire sensitivity when combined
with afternoon RH of 35 to 45% across the region.
Going into tonight, no big changes to the forecast. A line of
showers is forecast to reach the CT River around midnight along a
weakening cold front, with showers gradually expanding eastward
through the night but with a decaying trend based on today`s
12Z hi-res guidance. Western and northern NH and into the
western ME mountains stand the better chance of wetting rains
with up to 0.25" possible with amounts decreasing to the south
and east. Moist, southerly flow remains in place, so am
expecting more fog and stratus tonight, especially in western
ME, where fog could be locally dense. However, a limiting factor
to dense fog may be boundary layer flow being a hair more than
last night and this morning.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
There remains come uncertainty in how well the shower activity holds
together as it progresses eastward Friday morning, but the trend
will be for shower chances to decrease as the morning goes on as the
responsible wave exit to the east and the front washes out. Any
lingering fog should also clear by mid morning, except it could
stick around a little longer near the Midcoast.
For the rest of the day, isolated to scattered showers remain
possible with cyclonic flow in place and a small amount of diurnal
instability. Expect partly cloudy skies going into the afternoon for
much of the area, but skies could remain mostly cloudy farther east
into western Maine (toward Augusta and the Midcoast). This may keep
temps a little cooler if more clouds hang on, but highs for the most
part will be in the mid to upper 70s and even low 80s for portions
of southern NH and far SW Maine.
Except for a few showers across the north Friday night ahead of the
next frontal boundary, dry conditions should prevail. With the moist
southerly flow, more fog and low stratus is expected, especially
across portions of western ME, and valley fog may be limited farther
west over NH by increasing cloud cover. Overnight temperatures will
be milder ranging from the mid-upper 50s across the north to the 60s
in southern areas.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Saturday morning, moisture-laden air stemming from the remnants of
East Pacific TC Lorena will move into the area. The moist air could
increase PWATs up to nearly 1.8 inches by Saturday afternoon.  In
addition, some daytime heating and veering winds aloft could create
an environment where storms could become strong in the afternoon.
Model trends over the past 24 hours have shown an uptick in PWATs
and CAPE, which could allow for the possibility of gusty winds,
small hail and heavy downpours Saturday afternoon as a cold front
moves southeastward. New Hampshire will likely see more of an early
afternoon timing of the frontal passage, with it getting into
coastal Maine later on in the evening.
In addition, the aforementioned daytime heating may also make
Saturday feel a bit muggy and hotter. Highs could reach up to
85F, with some mid-day dewpoints approaching 70F.
Once the front passes, conditions start to improve, though a few
showers are still possible throughout the day Sunday. Skies clear
out nicely for Monday morning, as high pressure moves into New
England. Next week is looking pretty dry, though there may be a shy
chance to see a little bit of rain towards the end of the week.
Temperatures should run around average for this time of year, with
highs in the low to mid-70s most places.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Short Term...Prevailing VFR today except for RKD, but then IFR
to LIFR restrictions look likely again for many sites this
evening and tonight with fog and/or stratus. Rain showers are
also likely, especially across the western NH terminals through
tonight. Have not introduced precip to any other terminals yet
due to uncertainty in how far the precip will make it. Ceilings
and visibilities will improve on Friday, with NH terminals
expected to reach VFR, but AUG and RKD may hold onto IFR/MVFR
ceilings through the day. Fog and low stratus will be most
likely again for the western ME sites, especially RKD and AUG.
Long Term...
Lowered restrictions are expected from Saturday morning through
Sunday morning. Mostly VFR expected Sunday through the end of next
week.
&&
.MARINE...
Short Term...Southerly flow will continue to increase across the waters
through Friday night ahead of a couple of cold fronts. There could
be a brief period of SCA conditions south of Portland this evening
into tonight with gusts to around 25 kt. However, a longer duration
of SCA conditions are looking more likely Friday afternoon into
Friday night over the outer waters. Fog remains possible at times,
mainly east of Portland and Cape Elizabeth.
Long Term...
Southerly winds at 15-22kts and seas of 4-6ft should continue
through the end of the day Saturday. An SCA is likely to be issued
Saturday. Seas lower to 2-4ft and winds shift to westerlies Saturday
night. Winds will also weaken to 4-8kts by daybreak Sunday. Mostly
light and variable winds, with seas of 2-4 feet are expected through
most of next week.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory from 2 PM Friday to 8 PM EDT Saturday for
     ANZ150-152-154.
&&
$$
SYNOPSIS...
NEAR TERM...Combs/Ekster
SHORT TERM...Combs
LONG TERM...Palmer
AVIATION...
MARINE...

NWS GYX Office Area Forecast Discussion