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563
FXUS61 KGYX 202312
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
712 PM EDT Fri Sep 20 2024

.SYNOPSIS...
Low pressure south of Cape Cod meanders through tomorrow
before slowly drifting southward by early next week. The low
continues to bring cooler conditions, a few showers, and impacts
along the coastline. High pressure builds in across New England
by late this weekend and early next week, bringing seasonable
temperatures and dry conditions.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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710 PM Update... Went ahead and allowed the high surf advisory
to expire on time as the sun sets across the region. Radar
imagery continues to show mainly weak returns across the Gulf of
Maine and approaching the coastline with a few reports of
sprinkles thus far. Fine tuned PoPs through the overnight hours
based on latest radar trends and hi-res guidance, which keeps
the majority of mentionable PoPs along the immediate coast.
Otherwise, just made some minor adjustments to temperatures,
dew points, and winds.

Previously...
A large band of precipitation over the Gulf of Maine will
continue to attempt to retrograde westward as the moisture
interacts with dry air over land. This attempt at the pivoting
of precipitation remains in association with a nearly stationary
surface low southeast of Cape Cod along with an upper level low
stacked over the system. Most available guidance keeps much of
the region dry, but also brings some measurable rainfall to the
southwest coast of Maine and the Seacoast of New Hampshire. The
latest Namnest solution brings over a quarter inch of
precipitation to this region showing somewhat of a Norlun
looking inverted trough overnight. Will monitor the development
of this boundary this evening, however, considering how dry it
has been and dry level in place across the interior, this
precipitation may be overforecast and in more agreement with
other model solutions which keep limited precipitation over the
region.

Along portions of the southwest coast of Maine and the Seacoast
of New Hampshire, dangerous surf will continue with rip
currents.

Elsewhere, mainly dry conditions can be expected outside an
isolated shower. Patchy drizzle can be expected over southeast
New Hampshire and southern Maine with patchy fog as well once
again tonight.

Temperatures will be slightly cooler tonight, mainly in the
upper 40s and 50s.
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&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Any precipitation will be limited to far southern areas once
again on Saturday. Low pressure will remain southeast of
Nantucket before beginning its exit out to sea Saturday night.
Drier air will then enter all areas at that time setting the
stage with a sunny end to the weekend for all areas.

Highest temperatures will be over northern areas on Saturday
where the most sunshine will occur, mainly in the 60s.

A backdoor high pressure system will enter the region from the
Canadian Maritimes Saturday night. This will allow for
temperatures to be a little cooler, mainly in the 40s to lower
50s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Overview: Uncertain weather pattern evolving in the extended after
the breakdown of a block. After upper low lifts out of the Gulf of
ME...the blocky nature of the pattern will remain. Guidance attempts
to set up another rex block but the location remains low confidence.

Impacts: Pretty wide range of potential impacts...from continued dry
weather and increasing fire weather risk...to a more changeable
pattern with rain chances.

Forecast Details: The higher confidence portion of the forecast this
weekend will feature at least brief ridging as upper low departs the
local waters and drifts east. Northeast flow should keep temps on
the near normal side versus the mild weather of late. We will also
have to keep an eye on lingering moisture and potential fog/stratus
near the coast before westerly winds can sweep it away.

Beyond Mon a trof will approach from the west and that is where
forecasts diverge. Some guidance favors the base of the trof cutting
off and pinwheeling around for several days. Other guidance favors a
more progressive trof. Some of this may be tied to potential
tropical cyclone development in the Gulf of Mexico later in the
period...and ridge building ahead of it. Examining clusters in
DESI...guidance is roughly split 50/50 between the two
ideas...though the location of the cutoff will determine local
sensible weather. As a result I will not stray too far from the
multi-model consensus blend.

In general temps will gradually moderate thru the week. Rain shower
chances will develop by midweek and may linger into the weekend.

&&

.AVIATION /23Z FRIDAY THROUGH WEDNESDAY/...
Short Term...HIE and LEB may see nighttime valley fog again
tonight. A few showers are possible along the coast and southern
New Hampshire through at least tomorrow morning, and then
ceilings gradually improve to VFR by late in the day Saturday
into Saturday night.

Long Term...Generally VFR conditions expected to start the
period...though there is a low probability of some IFR or lower
conditions near the coast in marine fog/stratus. Local MVFR or lower
conditions possibly develop by midweek in SHRA as a trof approaches
from the west. Valley fog would be most likely Sun night/Mon morning
as surface ridge noses into the region from the northeast.

&&

.MARINE...
Short Term...SCA conditions continue over the outer waters through
tomorrow night as a gale center lingers south of Cape Cod. A
few gale force gusts can be expected near IOSN3. The system
gradually begins to drift southward by late Saturday, but seas
remain elevated even as winds begin to gradually decrease.

Long Term...Behind the departing low pressure northeast winds may gust
near 25 kt outside of the bays on Sun. That will support continued
wave heights above 5 ft. Those will gradually diminish thru the
week...but may remain at or above 5 ft thru at least Thu.

&&

.TIDES/COASTAL FLOODING...
We are at the peak of our astronomical tide cycle through the
weekend with the highest tides occuring during the afternoon
hours. Meanwhile, a gale center will remain south of Cape Cod
over the next few days. This will lead to multiple cycles of
minor coastal flooding due to storm surge values around a foot,
mainly from Portland and points south.

Beach surveys and Emergency Managers continue to indicate
compromised dune systems along the coastline from our storms
this past winter. Therefore, building nearshore waves may lead
to splash-over as well.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
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ME...Coastal Flood Advisory from 1 AM to 4 AM EDT Saturday for
     MEZ023-024.
     High Surf Advisory from 8 AM to 7 PM EDT Saturday for MEZ023-
     024.
NH...Coastal Flood Advisory from 1 AM to 4 AM EDT Saturday for
     NHZ014.
     High Surf Advisory from 8 AM to 7 PM EDT Saturday for NHZ014.
MARINE...Small Craft Advisory until 8 PM EDT Saturday for ANZ150>154.
-- End Changed Discussion --

&&

$$

NEAR TERM...Tubbs
SHORT TERM...Cannon
LONG TERM...Legro