342
FXUS61 KGYX 191447
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
947 AM EST Sun Jan 19 2025

.SYNOPSIS...
Weak high pressure briefly builds through early afternoon
before another wave forms along the front that tracks
northeastward towards the Gulf of Maine today and tonight. Snow
will spread into the area to the northwest of the track later
this afternoon and become heavy at times tonight. Then Arctic
air pours into the country and lingers through midweek.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
945 AM...Update mainly focus on today with adjustment to
Sky/T/Td based on current conds, and some tweaking of timing of
arrival of snow late this afternoon into early evening. Still
should be a mainly sunny day, at least into early afternoon
across much of the CWA, with clouds increasing after that and
maxes in the low 30s N to around 40 in the S.

6 AM Update...Have allowed the dense fog advisory across
southern NH to expire. However, have issued another one until 8
am for portions of central and southern ME as the fog has gotten
thicker over the last hour. It should lift fairly soon with cold
FROPA but until then low vsbys and icy roads will continue.

Previously...

Cold front pushes offshore very early on this morning with
locally dense fog, especially in the Merrimack Valley,
hopefully mixing out before dawn.

The morning hours will be fair with no precipitation along with
temperatures that will remain in the 30s to near 40 on the
coastal plain with 20s in the mountains. Clouds should scour out
for a few hours as well, allowing for a decent amount of sun
for awhile. Not a bad morning.

Low pressure at the SFC developing over Georgia as of 07z this
morning will move quickly northeastward to off the NJ coast by
00z this evening. Forcing for ascent will quickly increase late
this afternoon across southernmost NH and will allow for snow to
break out before sunset or near sunset.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
The snow will quickly spread northeastward this evening and
overnight and then quickly end by sunrise Monday. A very quick
mover.

Have converted most of the winter storm watch to winter storm
warnings albeit marginal. This looks like one of those fast
movers that yield no more than the 4-8 inch range which could
end up being an advisory for a portion of the warning area.
However, ratios are expected to be quite large so there will be
a "fluff factor" that should give most of the warning area
around a 6 inch snowfall. In addition, there are signs that
strong dendritic growth will occur for at least a few hours this
evening. The HREF is picking up on this possibility, showing
around a 60% chance for greater than 1 inch per hour snowfall
rates tonight, especially across southern NH and the ME coast,
where our highest confidence is in our snowfall forecast.

I addition, strong cold air advection overnight will aid in
gusty N/NW winds, possibly gusting to 25 to 35 MPH especially on
the ME coastal plain northward to portions of central ME. Given
the expected fluffy nature of the snow, have added blowing snow
to the forecast in these areas.

The system quickly moves out late tonight/early Monday morning
with cold air continuing to move on in.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
500mb shortwave and associated surface low will already be in the
process of lifting northward into the Canadian Maritimes Monday
morning with breezy northwest winds kicking in and bringing in drier
and colder air. So any lingering light snow across eastern areas
should quickly come to an end with continued decreasing cloudiness
going into the afternoon along with blustery conditions. Winds
gusting to 25 to 30 mph through the day will likely start wind
chills below zero in the morning (well below zero in the mountains),
and these won`t recover much through the day as temperatures likely
remain in the teens and even single digits in the mountains with
strong cold air advection.

Winds are forecast to gradually ease Monday evening and Monday as
the gradient relaxes, but there will still be enough of a breeze to
produce very cold wind chills as temperatures continue to fall with
the arctic air mass. Forecast wind chills south of the mountains are
-5 to -10F and -15 to -25F in the mountains, where cold weather
headlines may be required.

The arctic air stays put through Thursday before temperatures
moderate to finish up the week and to start the weekend. In general,
wind chills likely will be below zero in the evenings through the
morning hours south of the mountains and then limited to the single
digits during the afternoon as highs are only forecast to reach the
teens with somewhat breezy conditions. Wind chills in the mountains
are forecast to remain well below zero from the evenings through
morning and may not make it above zero during the afternoon as temps
only forecast to reach the single digits.

There may be some upslope mountains snow showers from time to time
Tues-Wed, but in general conditions look mostly dry during this
period. Good mixing will promote steep low-level lapse rates, and
Froude numbers do look to increase during the afternoons. This
suggests it could be cloudier than currently forecast south of the
mountains along with a few snow showers if we have enough low-level
moisture. Worth mentioning: models are showing a deepening low over
the western Atlantic as a shortwave approaches Tuesday night into
Wednesday. NBM slight chance PoPs suggest southern/coastal areas
could see very light snow out of this, but there is much more
support in the ensembles to keep this low well to the south and
east.

Thursday starts cold, but daytime highs will recover a bit as high
pressure shifts east bringing a return to southerly flow. Temps
continue to moderate for Friday and Saturday, and there are hints of
another coastal low moving late week as a northern stream shortwave
attempts to phase with southern stream energy. This will need to be
monitored as it could bring snow to portions of the area, but
ensembles currently favor a more offshore track and keep the bulk of
the QPF to the south and east.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
Short Term...VFR returns this morning after low clouds and
locally dense fog, especially in the Merrimack Valley lift.
However, expecting MVFR conds to return late this afternoon
with IFR or lower in SN at all terminals tonight. NW wind gusts
up to 30 KT possible tonight, especially on the coastal plain
northward to KAUG.

Long Term...Clouds continue to clear out from west to east Monday
morning with mainly VFR prevailing through Thursday. A couple of
exceptions will be the possibility of MVFR ceilings and snow showers
at HIE from time to time

&&

.MARINE...
Short Term...Seas subside today, but low pressure quickly moving
into the Gulf of Maine tonight will allow for low-end NWly
gales with some freezing spray possible.

Long Term...SCA conditions will likely continue Monday into Monday
night (maybe Tuesday as well) as low pressure lifts into the
Canadian Maritimes, and there may be a brief period of gales on
Monday. A distant low pressure passing to the south and east of the
waters may then bring another period of SCA conditions as winds turn
to the north/northwest, but that depends on its track. High pressure
builds toward the Northeast Thursday. By late week or the start of
next weekend, there is some signal for a coastal low pressure...but
confidence in any particular track is low as to weather it crosses
the waters or remains to the south and east.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory from 6 PM this evening to 7 AM EST
     Monday for MEZ007>009-012>014-033.
     Winter Storm Warning from 4 PM this afternoon to 7 AM EST
     Monday for MEZ018>028.
NH...Winter Weather Advisory from 6 PM this evening to 7 AM EST
     Monday for NHZ001>005.
     Winter Storm Warning from 4 PM this afternoon to 7 AM EST
     Monday for NHZ006>015.
MARINE...Gale Warning from 9 PM this evening to 7 AM EST Monday for
     ANZ150>152-154.
     Small Craft Advisory from 5 PM this afternoon to noon EST
     Monday for ANZ153.

&&

$$

SYNOPSIS...
NEAR TERM...Cempa/Ekster
SHORT TERM...Ekster
LONG TERM...Combs
AVIATION...
MARINE...