Winter Storm in Alaska, March 13 to 14, 2024

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
435 PM AKDT Wed Mar 13 2024

.SHORT TERM...While the initial weakening front diminishes over
the panhandle today, a quickly developing low in the gulf will
move northward and swing a gale force front towards the panhandle
tonight. As mentioned in the extensive previous discussion, the
parent low is set to be strengthening up until pushing inland
later Thursday morning east of Cape Suckling. The overall
forecast has stayed relatively on track with the primary impacts
from this system being widespread heavy precipitation, especially
the central and northern panhandle late Wednesday night through
Thursday morning as the front surges northward. For the Haines and
Klondike Highways, significant snow is expected closer to the
borders with Canada, while the towns of Haines and Skagway will
likely see little to snow accumulation with southerly winds
picking up tonight with the advancing warm front. A winter storm
warning has been issued for the Haines and Klondike highways with
the heaviest snow expected between 7 pm tonight and 7 am Thursday,
with additional minor accumulations possible heading into Friday.
For more on that, see the long term discussion.

For the southern panhandle, snow levels will likely reach excess
of 6000 ft, with the Icy Strait Corridor rising to at least 3500
ft. As such, there will be extensive snow melt at sea level and
elevation, which combined with heavy rain could lead to ponding in
poor drainage areas and rises in streams and rivers.

The other primary impact for this system will be gusty winds,
especially when combined with the expected heavy precipitation.
Southern POW Island is already seeing strong winds with gusts to
45 mph this evening, and these winds will continue to spread up
the gulf coast tonight as the front moves northward with the
strengthening parent low. For the inner channels, winds up to gale
force will spread northward with Lynn Canal expected to reach high
end gales as the gradient tightens when the parent low jumps
inland later Thursday morning. This will also lead to strong
winds with gusts of 45 mph or more along the Chilkat Peninsula as
well as Skagway, as well as a brief period for Juneau early
Thursday morning.

.LONG TERM.../ Friday through Wednesday / Building ridge over western
Canada from Friday and shifting east towards the Rockies by
Sunday. The southerly flow continues to stream across the eastern
gulf and over Southeast Alaska. This stream will push the warm
frontal like feature through the panhandle to the Northeast Gulf
Coast by Saturday morning. A good portion of the panhandle may be
dry Saturday to early Sunday until the upper level trough over the
gulf is lifting NE towards the panhandle, bringing the cold front
into the eastern gulf and to the panhandle to start the week.

The cold front will also bring in cooler temperatures across the
gulf to the panhandle, and this will push out the warm temperatures
that will have spread north through the panhandle Friday to Sunday.
A quick glance at record high temperatures for the weekend is
suggesting that a few locations may be approaching record values
Highs for the panhandle are looking to range from the mid 40s to
lower 50s.  Will need to watch this as have not been that optimistic
on cloud cover, if it clears out, there will likely be a degree or
two warmer than forecast.

With the warmer air and high freezing levels, there will be
additional snow melt with freezing levels rising Friday to Sunday,
so will need to keep an eye on river and stream levels.  The early
forecast today is hinting that the rises should stay below Action
Stage, only Jordan Creek in Juneau was reaching that level.  We will
continue to watch this situation.

&&

.AVIATION.../Until 00Z Friday/...Primarily CIG and VIS flight
conditions within the MVFR category are anticipated through the 24-
hour TAF period as the area will be under the influence of a warm
frontal system approaching from the southwest. Locations could
periodically dip down to within the IFR category under areas of
heavier precipitation. Any remaining frozen precipitation near
sea level at the beginning of the period should transition over
to liquid after the 1st 6-hours of the TAF period. Gusty SFC winds
are likely over the entire region, especially over the northern
Panhandle where the tightest pressure gradient will be situated.
LLWS magnitudes of up to around 45 kt out of a generally south to
southeasterly direction are likely, which will be centered up at
around 2 kft over the region as the front approaches and moves
through during the timeframe.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind from late tonight through Thursday morning for
     AKZ317.
     Winter Storm Warning from 7 PM this evening to 7 AM AKDT
     Thursday for AKZ318-319.
     Strong Wind from 1 AM AKDT Thursday through Thursday afternoon
     for AKZ318.
     Strong Wind from 1 AM AKDT Thursday through Thursday morning for
     AKZ319.
     Strong Wind from 10 PM AKDT this evening through Thursday
     morning for AKZ320-325.
     Strong Wind from 10 PM AKDT this evening through Thursday
     morning for AKZ323.
     Strong Wind from 1 AM AKDT Thursday through late tonight for
     AKZ327.
     Strong Wind through Thursday morning for AKZ328.
     Strong Wind from late tonight through Thursday morning for
     AKZ329.
MARINE...Gale Warning for PKZ012-013-021-022-031>033-036-641>644-651-
     661>664-671-672.
     Small Craft Advisory for PKZ011-034-035-053-652.

&&

SHORT TERM...STJ
LONG TERM....Bezenek
AVIATION...JLC

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Special Weather Statement
National Weather Service Juneau AK
343 PM AKDT Wed Mar 13 2024

AKZ320>332-141200-
Glacier Bay-Eastern Chichagof Island-
Cape Fairweather to Lisianski Strait-City and Borough of Sitka-
Admiralty Island-City and Borough of Juneau-Petersburg Borough-
Western Kupreanof Island and Kuiu Island-Prince of Wales Island-
City and Borough of Wrangell-Ketchikan Gateway Borough-
City of Hyder-Annette Island-
Including the cities of Gustavus, Hoonah, Tenakee Springs,
Elfin Cove, Pelican, Sitka, Angoon, Juneau, Petersburg, Kake,
Port Alexander, Craig, Klawock, Hydaburg, Coffman Cove,
Thorne Bay, Wrangell, Ketchikan, Hyder, and Metlakatla
343 PM AKDT Wed Mar 13 2024

...WARMING TEMPERATURES WITH PERIODS OF HEAVY RAIN INTO THE
WEEKEND...

A frontal band will spread more moisture Wednesday night and
Thursday into the panhandle, bringing a period of moderate to
heavy precip to the area, with the heaviest rates expected
Wednesday night into Thursday. Current 24 hour precipitation
totals for the panhandle from Wednesday morning through Thursday
morning range from 1 to 2.5 inches, with the highest totals along
the outer coast and southern panhandle. By the end of the work
week, the plume of moisture directed over more southerly locations
will shift northward, bringing another round of moderate to heavy
precipitation.

In addition to the heavy precip, another concern is a significantly
warmer low level airmass that is projected to move over the
panhandle. This warmer air may result in snow levels rising to
more than 5000 feet across the southern panhandle and from 2000
to 3500 feet over the northern panhandle by next weekend. Snowmelt
at higher elevations will add to the heavy precipitation near sea
level that may result in flooding along creeks, streams, and
rivers. Ponding in areas with poor or blocked drainage may also
become an issue.

We will continue to monitor this potential hazardous situation.