Heavy Snow in Alaska, December 29 to 30, 2022

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
153 PM AKST Thu Dec 29 2022

.SHORT TERM.../ Through Friday night / The trough extends from
the parent low south of the Central Aleutians, across the Gulf of
Alaska, and into the southern panhandle on Thursday. The trough
will move north through the panhandle and northern gulf through
Thu night and weaken. As the feature moves northward into the
northern zones should see 2 to 3 inches of snow falling from the
band of showers.

The rain-snow line will likely be from the Cross Sound area to a
little north of Angoon to Endicott Arm then along the coastal
mountains. Expect that Hyder should stay snow and north and east
of the line will be snow or potentially even a mix close to the
line.

A high-pressure ridge will remain in place over Western Canada so
the gap flow tonight is still on the breezy side. Gradients will
be slackening after the trough weakens so anticipate winds
diminishing so most will be 20 kt or less, with just the
Northcentral gulf coast hanging on to stronger easterly winds
within 30 miles of the coast.

.LONG TERM.../Saturday through Thursday/...A strong low pressure
system moves into the Western Gulf tracking toward Kodiak for the
weekend. The first associated front tracks into the NE Gulf
Saturday night with storm force barrier jet. This will bring the
first heavy band of precip to the NE Panhandle coast. Second front
more N to SE oriented and will bring in storm force winds to most
of the Eastern Gulf Sunday. Seas building to 30+ ft as well with
these advancing fronts. Inner channel winds will near gale force
as the second front tracks over the panhandle. In addition to the
increased winds the second front will bring in moderate to heavy
precipitation due to long fetch of tropical moisture. NE Gulf
Coast will be getting precip from both fronts and thus have
highest totals for the weekend. Rainfall totals of upwards of 2-3
inches for NE Coast with 1-2 for other areas for the event. With
the southerly flow and WAA raising surface temps into the 40s
precip will fall mostly as rain, with the exception of far
northern locations and at higher elevations. Those northern areas
that will remain mostly as snow could see accumulations of 4 to 8+
inches of heavy wet snow. Latest model runs were backing off on
PoP and precip totals for the southern areas as well as getting a
more defined/narrow band of storm force winds over the gulf. GFS
has been still most aggressive with the winds.

The low from the New Year storm system weakens and dissipates near
Kodiak Island Monday through Tuesday. Another developing low will
move northwards into the eastern half of the gulf. The models and
ensembles have poor agreement on positioning and strength, only
agree that something will move through around midweek.

&&

.AVIATION...Frontal trough tracking northward over the region is
causing rain showers over the southern TAF sites and snow in
Hyder. LLWS with ESE winds of 30-40kt between 1-2kft (some
occasional surface gusts) will track northward with the front.
That wind is keeping conditions MVFR at worst. Freezing levels
across the south will continue rising above 2kft while the
northern inner channels remains near the surface, and PAYA hovers
between the surface and 1kft over the next 24hrs. Therefore, as
the front reaches the north through Thursday evening, precip will
fall as mainly snow showers but easterly offshore flow ahead of
the front should keep CIGs higher than usual with snow. Behind the
trough, showers will be more widely scattered, winds will
diminish and become variable at times leading to potential for
some patchy fog.

&&

.MARINE...Gale force winds Thursday evening along the coast from
Cape Edgecumbe to Icy Bay then weakening Small Craft levels for
the outer coastal areas and and continuing mainly due to combined
seas at 8 ft or higher over the gulf waters. Incoming system
around Sunday has a vigorous front associated with it so there is
the potential of strong gale to low storm force winds suggested
at. Stay tuned for further updates on this storm.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind until 5 PM AKST this afternoon for AKZ323-328.
MARINE...Gale Warning for PKZ042-043-051.
     Small Craft Advisory for PKZ012-013-022-031-033-035-036-041-052-
     053.

&&

SHORT TERM...Bezenek
LONG TERM....PRB
AVIATION...Ferrin

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