Area Forecast Discussion
Issued by NWS Portland, ME

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976
FXUS61 KGYX 221444
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
944 AM EST Fri Nov 22 2024

.SYNOPSIS...
Low pressure will track north tonight, bringing rain to the
area overnight. The broad system will be slow to exit, with
chances for precipitation continuing through Saturday.
Conditions will start to dry out Sunday into Monday as the low
pressure lifts into the Canadian Maritimes.

&&

.NEAR TERM /THROUGH TONIGHT/...
930am Update...More of an overall update here to adjust morning
trends. Much of the precip has pushed north into the mountains
and Kennebec Valley at this hour. Here it may remain through
early afternoon while the southern CWA resides in a dry slot.
This will feature breaks of sun and fairly puffy cu. There is
low level instability present, but not too much moisture. Thus
these should be prominent through early afternoon. Can`t rule
out a brief shower out of these, but more isolated. Next, will
be focused on resumption of more widespread rain this evening
and overnight.

8am Update...Quick update here to expire Gale headlines on the
coastal waters and put up SCAs through this evening. Winds will
fall off early this morning, but wave action of 5 to 8 ft is
still expected through today.

628 AM Update...
The steady rainfall will continue to quickly retreat to the
north this morning. In its place a lighter southeast flow will
develop. Scattered showers shown on latest KBOX radar imagery
will cross the region from time to time, similar to the most
recent HRRR solution. Winds will continue to diminish this
morning from north to south as well this morning as the dry slot
rolls through. Otherwise, only minor modifications to the
latest forecast package.

Prev Disc...
Low pressure retrogrades through eastern New York this morning.
A moisture band will finally pivot across the forecast area
around the vertically stacked system. Rain will continue across
the region this morning before a dry slot enters the region from
the south. Will taper off pops from the mid morning hours to
early this afternoon over southern and central portions of the
forecast area. Across the far north, rain will continue into the
afternoon hours with some snow mixing in over the higher
elevations.

The strong, gusty winds will diminish during the day as the
gradient relaxes. Temperatures will climb into the 40s north by
afternoon with lower 50s in the south.

&&

.SHORT TERM /SATURDAY/...
Models continue to develop an areas of low pressure well off the
southern New England coastline tonight. There is some
disagreement in the track and intensity of this system which
impacts the timing of precipitation retrograding back into the
forecast area from east to west during the night. In any case,
will lean towards categorical pops after midnight in most areas.
The NamNest and other models do show a fairly potent inverted
trough entering the area.

Rain will continue on Saturday as the system intensifies and
briefly stalls over the Gulf of Maine. Ptype will be an issue
as well as enough cold air will be present in the northern
mountains and also portions of western New Hampshire to allow
for snowfall. It will be cooler, with highs only in the 30s
across the mountains with lower to mid 40s elsewhere.

Have upped the winds a tad for Saturday and this may need to be
increased further. A tight gradient behind a departing strong
area of low pressure may lead to very gust winds out of the
north and northwest. Bufkit profiles suggest a brief period of
35kt+ winds is possible during the day and into the evening
hours.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
04Z Long Term Forecast Update...
Latest ensemble and global forecast guidance continues to
indicate unsettled conditions to persist until Saturday night as
low pressure drifts to the Canadian Maritimes. While doing so,
colder air will be brought down from the north with
northwesterly flow and this could allow for a brief period of
wet snow to mix in south of the mountains before ending. Another
s/wv trough looks to cross on Sunday, bringing additional
rain/snow showers that will be mainly confined to the
north/mountains. Brief s/wv ridging builds on Monday, allowing
for dry and mainly sunny conditions. The pattern becomes more
unsettled again mid-late week as the next storm system
approaches the region.

Broad upper low will be centered near Cape Cod Saturday
morning, and waves of energy rotating to the north and west over
the area will prolong cloudy and rainy conditions for at least
the morning hours with snow toward the north and higher
elevations (although a few flakes may mix in early farther to
the south). The upper low will gradually move off to the
northeast through the day and into Saturday night, and there`s
still come uncertainty among the models on how quickly this
occurs, but the general trend will be decreasing precip chances
south of the mountains going into the afternoon and evening,
although could be more Saturday night per the ECMWF. A surface
low will also be deepening as it lifts northward into Nova
Scotia, and with the tightening gradient expected breezy
conditions to develop by the afternoon with gusts of 20 to 30
mph possible.

Once precip tapers off, skies are expected to remain partly-
mostly cloudy south of the mountains through Saturday night
while the mountains stay cloudy with scattered upslope snow
showers.

Stacked low pressure will remain near the Canadian Maritimes on
Sunday leaving northern New England in a northwest flow, which
will be on the breezy side with a tight pressure gradient. Based
on latest forecast soundings, we`re looking like upwards of
25-30mph. Rain and snow showers will likely continue across the
north and mountains, and a few of these may occur downwind of
the mountains if we can get enough daytime instability and
Froude numbers are high enough (the NAM is more supportive of
this) as there will be an upper trough nearby.

The upslope precip in the mountains will wind down either
Sunday night or early Monday as high pressure briefly builds
into the region bringing a dry day with seasonable temperatures
mainly in the 40s. As quickly as the high moves in, it will
quickly give way to an upper trough and surface low moving
across the Great Lakes that bringS the next shot at widespread
precipitation Monday night and into Tuesday. Temperature profiles
may be cold enough to support some snow or even a mix Monday
night or Tuesday morning, but confidence is low and would probably
be across northern areas if anywhere.

After this system passes, there is a good support among the GFS
and ECWMF ensembles members with dry conditions on Wednesday
(other than mountain upslope snow showers). Going into next
Thursday/Thanksgiving, the operational GFS is hinting at low
pressure potentially bringing some snow to the area, but this is
the faster solution with many of its ensemble members (as well
as the ECWMF) keeping conditions mostly dry. The NBM PoPs of
slight chance across southern areas capture this well.

Lastly, there is pretty high confidence in a cooler airmass
arriving toward the end of next week, and even though this is
just beyond the extended forecast, there is a signal for what
could be the first measurable snowfall of the season for many
areas. This would potentially be in the day 8 or 9 time period,
and as always this far out, details (such as amounts and timing)
are uncertain.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
Short Term...Winds slacken this morning as some improvement in
restrictions with IFR becoming MVFR and perhaps VFR later in the
afternoon. Another round of lowered ceilings arrives Friday
night with RA. More in the way of SN may be possible along the
western ME mountains and the Whites Friday night. These lowered
condition continue Saturday.

Long Term...Conditions look to improve to VFR late in the day
into Saturday night with the exception of HIE and LEB, where
MVFR ceilings and possibly rain and snow showers continue
through Sunday or even Sunday night. . Elsewhere, mostly VFR
expected Sunday and Monday with northwest wind gusts 25-30 kt
possible on Sunday. A few rain or snow showers may also develop
Sunday afternoon. Another low pressure system looks to bring
increasing precipitation chances Monday night and Tuesday along
with flight restrictions.

&&

.MARINE...
Short Term...Winds slacken early this morning, falling below
SCA criteria. However, wave heights remain 5 to 8 ft today
into the evening outside of Penobscot Bay. Another set of gales
may be needed for Saturday.

Long Term...Conditions may be able to fall to below SCA levels
late Monday or Monday night as high pressure briefly builds in
before winds increase ahead of and also behind a low pressure
and front that look to cross around Tuesday. Another area of low
pressure may approach the waters toward the end of next week,
but confidence is low on timing and potential track of the low.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 10 PM EST this evening for ANZ150-
     152>154.
     Small Craft Advisory until 11 AM EST this morning for ANZ151.

&&

$$


NEAR TERM...Cannon/Cornwell
SHORT TERM...Cannon
LONG TERM...Tubbs