Gale Warning 67, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
533 AM AKST Thu Feb 8 2024

.SHORT TERM...Satellite and radar data indicate that the clear
skies that SE AK enjoyed on Wednesday have disappeared. In their
place a cloud deck has moved back in, associated with a weak
system which will move off to the SE through Thursday. Expect
chances of showers across much of the panhandle with this system,
especially along the outer coast. Do not expect more than minor
snow accumulation with this system, given its lack of moisture and
dynamic support.

The big story will be a far stronger system arriving on Friday.
This system has the potential to bring with it respectable
accumulating snowfall, along with windy conditions, rain, and
ultimately a warmup in temperatures for much of the area. For
additional details, see the long term forecast discussion.

.LONG TERM...Continuing from the short term, a strong low in the
western gulf will push a storm force front towards the panhandle
Friday bringing gale force winds to the NE gulf and moderate
precipitation to the northern half of the panhandle. With a cold
stable airmass in place ahead of this front, precipitation will
start as snow with a transition to mix along the Icy Strait
corridor and possibly all rain by Saturday afternoon.

The difficulty in this forecast timeframe as usual for this time
of year is the transition for precipitation type. While strong
northerly outflow winds do not exist to oppose the progression of
the surface front, the cold stable airmass in place will still
provide resistance. Also, the surface front is far removed from
the parent low, and therefore may not have as much northward
momentum behind it after it reaches the outer coast. If the front
struggles to push inland, winds in the inner channels may remain
light or weakly out of the north. In this scenario, precipitation
would remain snow for longer leading to higher storm snowfall
totals. With this in mind, Juneau could see storm accumulations
from Friday through Saturday morning of 10 - 15 inches (25%) with
lesser totals across Icy Strait communities as well as Elfin Cove
and Pelican. If the front is more progressive, a transition to
mixed precipitation or rain could occur as early as Friday night.
This would lead to significantly lower snowfall amounts across the
area.

In either scenario, southerly flow will eventually push in and the
panhandle will see increasing temperatures through the weekend.

&&

.AVIATION.../Until 12Z Friday/..Primarily VFR conditions are
anticipated through the period with the exception of some
intermittent MVFR conditions caused by isolated snow showers from a
disturbance moving over the northern 2/3 of the Panhandle through
mid-morning Thursday. SFC winds of 10 kt or less and rather
minimal LLWS look to be the story for most areas through the TAF
period. The exception to this looks to be for the Northern Lynn
Canal area, including Haines and Skagway, which may see winds
gusting up to around 20 kt through the period from a tightened NE
to SW pressure gradient.

&&

.MARINE...
Gulf and Coastal waters:
A storm force low enters the gulf Thursday, resulting in an
increase in southeasterly winds Thursday across the northern
coast, reaching gale force along most of the north by early Friday
morning, with storm force likely near Cape St. Elias into Prince
William on Friday. These winds will build steep 10-14ft seas from
the southeast, before a dominant southwest swell impacts the Gulf
later Friday into Saturday. Looking at the dynamic fetch and
winds of this system, with wave nomograms, there is agreement on
18-22ft seas; wave guidance concurs. However, if this system
deepens further than anticipated, could see 25ft significant wave
heights.

Inner channels:
Winds continue to be between 10 to 20 kt across the inner
channels through Thursday. The pressure gradient tightens up
Friday morning, with strong southerlies impacting the central and
southern Panhandle, with gale force likely out of Cross Sound.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gale Warning for PKZ644-652-662>664-671-672.
     Small Craft Advisory for PKZ022-035-036-053-641>643-651-661.

&&

SHORT TERM...GFS
LONG TERM....STJ
AVIATION...JLC

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