636
FXUS61 KGYX 230400
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1100 PM EST Fri Nov 22 2024

.SYNOPSIS...
Low pressure will track north tonight, bringing another round of
steady rain to the area tonight and into Saturday. The broad
system will be slow to exit, with chances for precipitation
diminishing late in the day Saturday into Saturday night.
Conditions will start to dry out Sunday into Monday as the low
pressure lifts into the Canadian Maritimes. Another low pressure
will bring the next chance of widespread precipitation around
Tuesday of next week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...

11:00pm Update... Minor tweaks to POPs based on recent radar
trends to bring the expanding rain shield in a little sooner.
Also brought up temps slightly for tonight, but overall this
didn`t affect the snowfall expectations as they hold off until
winds turn more northerly late tonight. Otherwise, the forecast
remains on track at this point.

7:25pm Update... Rain continues to rotate toward the area this
evening, with the leading edge of the steadier rain moving into
southern New Hampshire at this hour. Temps are running a bit
warmer across interior locations than previous thinking, but
these should steadily cool to the wet bulb temp as the rain
continues to overspread through the evening. Overall no notable
changes with this update as the forecast remains on track.

Previous...

Broad circulation of stacked low pressure dominates the
Northeast this afternoon. It`s symmetry is fleeting however as a
strong mid/upper jet rounds the base, ejecting off the coast of
the Southeast this evening. Jet dynamics will be favorable for
additional surface low pres development tonight towards the
Gulf of Maine. Through Saturday morning, this new surface low
will undergo a similar process as the low just last evening, but
translated 200 miles east.

Moisture advection is more meridional and readily available this
evening, thus expect a more widespread precip shield for the
CWA tonight. Steady precip will be moving in around midnight,
with showers increasing in coverage beforehand. Rain is expected
for most locations, but snow will be possible for higher
elevations. Winds slowly shift north overnight as the low nears
Nova Scotia around daybreak.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Wind and morning rain highlight Saturday, in the mountains,
accumulating wet snow likely.

Low pressure will make its closest pass to ME early Saturday
afternoon, sharpening a pressure gradient across northern New
England. Expect winds to increase early, peaking through the
afternoon and continuing into the evening hours. Momentum
transfer has some peaks sampling 45 to 50 mph for the Kennebec
Valley region and again for southern NH. However, the spread is
wide, and average gusts should fall below these for the day. A
more realistic forecast for tomorrow is gusts of 30 to 40 mph
for the region. Wind orientation relative to the mountain ranges
limits downslope enhancement prospects for this event.

The precip shield that pushed into the region overnight will
slowly slide east as the day goes on. Behind it, cold air
advection and wetbulbing may promote some flakes mixing in
outside of the mountains, however accumulation is unlikely as
precip rates lighten and ground temps remain mild.

Breezy NW winds continue into the evening and overnight hours.
This bring in a good setup for upslope snow continuing for
northern NH and the western ME mountains. Froude numbers are
subcritical, leading to much of this activity remaining upstream
of the ridges. That said, enough low level moisture remains
locked in for light accumulations into Sunday morning.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...

Long Term Update...

Ensemble suites remain consistent on bringing precipitation into the
area during the Tuesday through Tuesday Night timeframe, but have
trended slightly lower in terms of QPF. Uncertainty remains on how
organized this system will become by the time it`s moving through
New England. A much wider spread amongst the models continues for
the system later in the week. This one continues to have the
potential to be a more impactful system, but the GEFS continues to
show a much weaker and less impactful system than the Euro
Ensembles.

Full Discussion...

Stacked low pressure stays across the Canadian Maritimes on
Sunday, leaving northern New England in a breezy west-northwest
flow with forecast soundings suggesting gusts 25-35 mph,
possibly over 40 mph on occasion as the gradient remains tight.
Snow showers will likely continue in the mountains with the
upslope flow, and there are signals for a few rain or snow
showers for areas downwind of the mountains as well with low-
level lapse an upper trough axis swinging through in the late
morning or early afternoon. This is supported by forecast
soundings showing steep low-level lapse rates and a little bit
of instability, so I have also gone a little bit higher on cloud
cover.

If anything develops south of the mountains, it will diminish
toward sunset, but scattered snow showers will continue in the
mountains through at least Sunday night, possibly into the first
part of Monday as well. The rest of the area will see dry
conditions on Monday as high pressure briefly builds with still
somewhat breezy conditions.

The next shot at widespread precipitation occurs either late
Monday night or Tuesday as models are in good agreement showing
a progressive system crossing through. Ensemble means from the
GFS/ECWMF suggest QPF on the order of 0.25" to 0.50" with this
system, and most of this is expected to be rain, except snow or
even a mix is possible across the north and higher terrain. It
should be noted that a few solutions (mainly the ECMWF) are
farther south with the low pressure which would in turn bring
the potential for the wintry precip a bit farther south as well.
This system quickly exits Tuesday night with a dry day for
Wednesday, other than the usual upslope snow showers in the
mountains.

There remains a signal in today`s 12Z model guidance in a
developing low pressure off the Mid-Atlantic and lifting
northeast toward the end of next week. As alluded to in
yesterday`s discussion, there is more confidence in a colder
airmass moving into the region, and this low could bring the
first measurable snow of the season for portions of NH and
western ME if it comes to fruition. Some guidance is suggesting
as early as Thursday night, but there is a better support within
the ensembles to favor Friday or even Saturday for the higher
PoPs at this point.

&&

.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
Short Term...Cigs again lower this evening as another round of
rainfall moves in tonight. MVFR to IFR is expected, with limited
vis in light to moderate rain. North winds increase by Sat AM,
gusting 30 to 35 kt at times Saturday. Winds slacken overnight,
becoming NW into Sunday morning. Ceilings will begin to improve
towards VFR for terminals outside of the mountains late
Saturday afternoon. This comes as the RA shield pulls east. More
in the way of SN is possible for this evening for terminals NW
of the mountains. Snow showers continue here Saturday night
with IFR.

Long Term...HIE may continue to see MVFR cigs and/or snow
showers Sunday into Sunday night, but otherwise VFR conditions
expected Sunday and Monday. Winds will be continue to be breezy
on Sunday with gusts 25-30 kt, possibly up to 35 kt on
occasion. A brief rain or snow shower may also occur south of
the mountains Sunday morning or afternoon, but chances look like
they`ll be too low for any TAF inclusion once we get to that
point.

Another system expected to move through around Tuesday with
flight restrictions looking more likely. Precip type is expected
to be mainly rain, but there could more of a mix at HIE and
LEB. VFR returns Wednesday, except the possibility of upslope
rain/snow showers at HIE once again.

&&

.MARINE...
Short Term...Two areas of low pressure will drift south of the
coastal waters this evening. These will pull north with time
overnight, spreading additional rain into the region and winds
shifting north. These lows consolidate over Nova Scotia, with a
tight pressure gradient across the region. A long period of gale
conditions will result Saturday and Saturday night, potentially
lasting into Sunday. Can`t rule out a few gusts to Storm force
along the Midcoast as the low nears Saturday afternoon.

Long Term...Low pressure over the Canadian Maritimes and a
tight gradient will keep at least SCA conditions on Sunday and
Sunday night, but it`s certainly possible gusts could continue
to exceed gale force during the day Sunday, especially over the
outer waters. Some improvement is possible on Monday or Monday
night winds and seas increase again on Tuesday into Tuesday
night as low pressure quickly crosses the region. Brisk westerly
winds follow this system on Wednesday, and there`s potential
for another low pressure to pass near or just south of the
waters toward the end of next week.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Gale Warning from 7 AM Saturday to 7 AM EST Sunday for
     ANZ150>154.

&&

$$


NEAR TERM...Clair
SHORT TERM...Cornwell
LONG TERM...Combs