Area Forecast Discussion
Issued by NWS Portland, ME

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480
FXUS61 KGYX 191040
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
640 AM EDT Thu Sep 19 2024

.SYNOPSIS...
A developing offshore storm brings cooler air and enough
moisture for some scattered showers over the next couple of
days. Increased surf and some minor coastal flooding are also
likely with this system. High pressure then builds in from the
north late this weekend with seasonable temperatures and dry
weather expected.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

6:40am Update... No notable changes with this update, mostly
just fitting temps to trends so far this morning. A bit of fog
has made its way onshore, but it expected to mostly burn off by
mid morning.

Previous...

A developing offshore storm takes control of the weather
pattern starting today, and continues for the next several days.
Cooler temps and cloud cover will be the most notable change
today, with some light scattered showers also possible at times
across southern areas. Easterly flow keeps the coastline the
coolest with highs around 70, and some patchy fog in the morning
as well. Farther north and west, one more day with temps in the
low 80s and mostly sunny skies is expected.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
The trend continues tonight, with more clouds, a few showers,
and some patchy fog through coastal and southern areas. The
northern valleys see mostly to partly clear skies overnight,
allowing for some fog through the northern valleys overnight
tonight. Lows look to mainly bottom out in the 50s to near 60
overnight.

Tomorrow looks similar to today, but cooler and with a better
chance for showers as the offshore storm makes its closest pass.
Highs mainly range from the mid 60s along the coast, to the mid
70s across northwestern areas. The chance for showers also
extends into central New Hampshire as well, but any rainfall
amounts look to remain light, with generally less than a tenth
of an inch expected.

Surf and rip currents will also be elevated by tomorrow by the
storm, with dangerous rip currents likely, especially across the
beach of southern Maine and New Hampshire.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
12Z operational models and ensemble solutions continue to
suggest a relatively disorganized area of low pressure will
remain southeast of Nantucket Island as we begin the extended
portion of the forecast. During the period Friday through midday
Saturday, moisture will be attempting to reach southern portion
of the forecast area as moisture from off the coastline
collides with drier air over the interior. A northern and
western adjustment to the QPF has occurred since yesterday. This
is more consistent with the latest operational Canadian and
European runs but less in par with its ensemble solutions. In
any case, have raised pops across portion of the region, but
still on the low side of guidance. Despite the cloud cover,
temperatures will likely top out over 70 degrees in most
locations.

Models also remain in relatively good agreement that this
system will begin to exit out to sea late Saturday allowing
Canadian High pressure over the Maritimes to retrograde back
into our region. This will allow for drying with any leftover
showers beginning to dry up by Saturday evening.

The Canadian High will allow for dry and seasonable conditions
Sunday and Monday across the Northeast. Temperatures will be
near normal for this time of the year.

The next chance for significant precipitation will hold off
until Tuesday and Wednesday of next week. A complex frontal
system will enter the region from the west accompanied by a
vigorous upper level trough that will track over the Great
Lakes. Temperatures will be seasonably cool for this time of the
year.

Coastal Flooding...The onshore winds forecast for the coast on
Friday will coincide with very high astronomical tides. This
may lead to minor coastal flooding near the times of high tide
during the early morning hours Friday, but moreso and more
likely during the Friday afternoon high tide.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
Short Term...Coastal fog lifts at most terminals this morning,
with RKD holding onto it most of the morning. Any valley fog at
HIE and LEB burns off by mid morning. VFR is expected at most
terminals, except at RKD. More fog and periods of LIFR
conditions are expected at most coastal terminals tonight, with
valley fog possible at HIE and LEB. Mainly VFR conditions are
expected tomorrow.


Long Term...VFR likely prevails during the day time late
Saturday and Sunday with MVFR conditions possible in scattered
showers Friday into Saturday. Night time valley fog will bring
the potential for IFR/LIFR most nights at KLEB and KHIE. Onshore
flow and increasing clouds from a system passing south of New
England will also bring the potential for cigs around MVFR
thresholds Thursday night and possibly into Friday.

&&

.MARINE...
Short Term...A developing gale center south of Cape Cod brings
freshening east to northeasterly winds starting today, and
continuing through tomorrow. SCA conditions are likely by late
today with building seas across the southern waters, and
possible elsewhere by late tonight outside of the bays.

Long Term...Low pressure passing south of the Gulf of Maine
will bring seas building to 5 ft by Friday with continued NE
flow with gusts around 25 kts, reaching SCA criteria. Seas
remain elevated around 5 feet into the weekend with NE winds
subsiding from their peak on Friday.

&&

.TIDES/COASTAL FLOODING...
High astronomical tides will combine with a strengthening
onshore flow over the next few days. Minor coastal flooding is
possible for several tide cycles, starting tonight and lasting
through at least Sunday. Waves will also build by Saturday, with
the greatest impacts due to waves likely along the New Hampshire
Seacoast.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory from 6 PM this evening to 8 PM EDT Friday
     for ANZ154.

&&

$$


NEAR TERM...Clair
SHORT TERM...Clair
LONG TERM...Cannon