Extreme Cold in Alaska, January 2 to 4, 2025

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
455 AM AKST Thu Jan 2 2025

.SHORT TERM...Winter continues across the panhandle with the cold
dry outflow pattern continuing to dominate. Areas protected from
outflow winds will continue to see colder than normal minimum
temperatures due to increased radiational cooling overnight. In
the far northern panhandle, the Klondike Highway will continue to
see hazardous cold temperatures, reaching as low as 40 below
Thursday night into Friday morning as cold air continues to funnel
through from the interior and winds increase with gusts up to 50
mph. A decaying front extending from a low approaching the gulf
will bring some light showers to the far southern panhandle later
tonight, with a low chance of making it past Sumner Strait. This
will however increase the N/S pressure gradient, causing winds to
pick up further along Lynn Canal and other such oriented inner
channels Thursday evening and overnight into Friday.

Overall little changes made to inherited forecast aside from
adjustments to winds based upon observations, as well as tweaks to
temperatures to reflect disparity between sheltered and non
sheltered areas.

.LONG TERM...While outflow winds have underperformed this week,
expecting peak conditions by Friday as pressure differences
between Whitehorse and Juneau reaches 18 to 20mb. Historically we
see around 40 to 45 knots of sustained wind in Lynn Canal/northern
Chatham and fully developed seas near 13ft. Heavy freezing spray
is also a concern around Taiya Inlet. Elevated winds of 25 to 30
knots continue Saturday before diminishing Sunday for Lynn Canal.

Over the weekend expect a pattern shift from cold/dry to
wet/warm, with a portion of the forecast challenge focused on
timing of snowfall transition to rain. For now, expect some light
snow to move over the region Friday, with 24-hour totals of a few
inches later Saturday into Monday for most of the Panhandle. If
we can sustain cold air at the surface as the AR moves in Tuesday,
significant accumulations are likely for portions of the northern
Panhandle. For now, the current forecast reflects a transition to
warmer air mid-week as snow levels rise above 1,000ft, keeping
24-hour snowfall accumulations less than advisory levels.

Significant wave heights along our near shore northern coast
should remain at or below 12ft until late Saturday, with
southeasterly near-gales increasing seas to 12ft to 15ft south of
Cape Suckling. A larger threat emerges Monday. Guidance is
starting to show agreement on a storm force low south of Kodiak by
Monday into Tuesday which would increase winds to gale force
along most of our coast and Hecate Strait, potentially reaching
storm force. Confidence is high that 20 to 25 ft, potentially
30+ft, seas return Monday or Tuesday for the gulf, complicating
any travel through our coast and Dixon Entrance. Southerly near-
gale to gales likely for some inner channels by Tuesday

&&

.AVIATION...Another day of predominant VFR flight conditions
expected through under SKC across panhandle. Main aviation concern
through the period will be winds, strongest winds expected near
Skagway and Haines with sustained winds 20 to 30kts with isolated
gusts up to 45kts possible through the afternoon as pressure
gradient tightens in the Lynn Canal. Cross- barrier mountain waves
and outflow winds continue through today, especially near Taku
Inlet and over S Gastineau Channel.

&&

.MARINE...The northerly outflow currently impacting the panhandle
is expected to remain relatively stagnant through the first half
of Thursday. Strong breezes to gale force winds are expected to
continue in north south facing channels, particularly Lynn Canal,
Chatham Strait, Stephen's Passage, and parts of Fredrick Sound. A
frontal band moving northward from a system in the northern
Pacific Thursday night will enhance pressure gradients across the
panhandle, bringing up wind speeds. Though weakening as it
approaches, this frontal band will bring increasingly easterly
winds to the southern half of the panhandle. Seas in Lynn Canal
are expected to become fully developed down to around Point
Gardner by Thursday evening, with up to 13-15 ft seas expected.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Cold Weather Advisory until 9 PM AKST this evening for AKZ318.
     Strong Wind through late tonight for AKZ318.
     Extreme Cold Warning from 9 PM this evening to noon AKST Friday
     for AKZ318.
MARINE...Gale Warning for PKZ012-013-661.
     Small Craft Advisory for PKZ021-022-031-032-034-641>644-651-652-
     662>664-671-672.

&&

SHORT TERM...STJ
LONG TERM....AP
AVIATION...NM
MARINE...STJ

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