548
FXUS61 KGYX 251057
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
657 AM EDT Wed Sep 25 2024

.SYNOPSIS...
High pressure retreats northward as moisture works its way into
the region today and tonight. Low pressure keeps north as a
triple point of fronts moves through the area Thursday. This
brings much needed rainfall to the area, albeit heavy at
times. Dry weather returns in time for the weekend as high
pressure moves overhead.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
7am Update...Expanded rain chances in western NH this morning.
Showers have been drifting through NY and VT overnight, and look
to clip NH for a couple hours. Precip is expected to be light,
but will create some damp spots through noon. Otherwise, a few
passing sprinkles continue in southern NH and ME.

Previous Discussion...
Cloudy and cooler today ahead of wetting rainfall tonight
through Thursday.

Onshore flow will continue today, bringing with it moist low
level air. This will be responsible for a lower deck of cloud
for much of the coast and interior today, with some breaks in
the mountains and towards the Quebec border. Can`t rule out a
sprinkle here and there as upper moisture also passes through
the region from the SW. Should dry layer thin enough in places
through the morning hours, could see brief seeder/feeder
showers.

With the clouds in place, went a little lower than guidance
today for highs. Highs in the mid to lower 60s are forecast for
much of the area. This may only be exceeded by southern NH
locations which have instead been insulated by the overnight
cloud, missing a window of radiational cooling in the Tues
evening hours.

Along the coast, there remains waves of 5 to 6 ft at long
periods that can bring moderate to high surf and rip currents.
Will continue to assess the needs for any coastal products, but
current thinking is more overcast today will lead to less
crowded beaches.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Mild tonight as cloud cover from the daytime sticks around. The
area will also see increasing WAA through much of Thursday as
return flow strengthens ahead of incoming low pres from the
north.

Tonight, shower chances increase west to east as low pres
advances. There is uncertainty on exact start time of steadier
rain, but it should be falling come Thursday morning for much
of the interior and northern NH. The day shift already pointed
out some good parameters to watch for this much needed batch of
rain including a favorable PWAT range and warm cloud depth of
around 12 kft. With some elevated instability present, I added
mention of thunder in the afternoon across southern NH and ME.
This comes into play around when upper level 140kt jet flattens
with good net lift across the CWA. Some longer time frame CAMs
are picking up on the likelihood of heavy rain, Thursday
afternoon. HRRR and NAMnest are trying to even resolve a fine
line of convection developing in the region. Strong winds with
this line are currently not forecast, but can`t rule out some
additional gusts amid a quick wind shift as this passes. The
biggest impact may be very heavy rainfall as it passes, reducing
visibility and contributing to the risk of hydroplaning around
the afternoon commute.

The threat of flash flooding remains low due to the very dry
antecedent conditions, as well as progressive nature of this
system tonight through Thursday. That said, some enhanced
rainfall rates could lead to nuisance ponding of water around
low spots as well as if any storm drains have collected the
first fallen leaves of the season.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Overview: The period will start wet as a 500mb trough dives
into the region and moves overhead Friday. It exits by Friday
night followed by height rises through the weekend. The ridge
axis looks to be centered on us Monday, before another trough
approaches Tuesday along with another chance for showers.

Impacts:
* No significant weather impacts expected.

Details: Showers exit the area shortly after sunset and skies
begin to clear overnight, but gradual enough that low
temperatures likely only bottom out in the 50s.

There will be just enough moisture wrapping around the low on
Friday to squeeze out a couple light showers, mainly in and
around the mountains, as the upper low slowly exits through the
day. Otherwise, high pressure begins nosing in from the north
so mostly clear skies will allow temperatures to warm into the
upper 60s and low 70s from the foothills south, and in the
mountains and points north, northerly flow and a tad more cloud
cover will keep temperatures in the low 60s. Low temperatures
Friday night will be a bit cooler than Thursday night, but
lingering clouds will keep them very similar. High pressure
takes full control for the weekend with Saturday and Sunday
featuring mostly clear skies, calm winds, high temperatures in
the 60s, and low temperatures in the upper 40s.

High pressure looks to hang on for Monday before the pattern
becomes a little more uncertain due to the fact that Tropical
Cyclone Helene will be moving inland in the southern U.S. This
will have an effect on the timing of the next trough, as
differences in global models currently show, so will stick with
the NBM low chance PoPs on Tuesday for now.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
Short Term...MVFR today for most terminals, with periods of IFR.
A trend towards VFR is possible for RKD/AUG this afternoon, but
the trend returns to MVFR/IFR restrictions after midnight into
Thursday. SHRA works into the region overnight, becoming RA for
Thursday. Some TS possible in the afternoon for mostly southern
terminals. RA may be heavy at times, causing additional vis
restriction.

Long Term...Thursday will likely feature a mix of MVFR and VFR
ceilings as rain, locally heavy,moves through the area. Friday
morning may feature some fog but afterward VFR should be the
prevailing condition right through the weekend. Winds will be
light with gusts generally 10-15kts.

&&

.MARINE...
Short Term...Wave heights 4 to 6 ft continue through Thursday,
mainly for the waters south of Penobscot Bay. Have extended the
SCA through to Thursday evening. This may need extension
northward for tomorrow. Wave heights and periods continue to
align for possible high surf at times. Either way, those
recreating along the beaches should be aware of moderate rip
current risk, potentially extending through late week.

Long Term...Max wave heights of 5ft remain through at least
Friday morning before finally dropping below 5ft later in the
day and remaining below SCA criteria through the weekend. Winds
will be gusting 15-20 kts on Thursday and Friday before high
pressure begins to move over the waters and calm them a bit for
the weekend.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 8 PM EDT Thursday for ANZ152>154.

&&

$$


NEAR TERM...Cornwell
SHORT TERM...Cornwell
LONG TERM...Baron