Storm Warning 27, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
517 AM AKST Sat Dec 21 2024

.SHORT TERM...The active pattern continues, with stronger systems
which will bring more robust precipitation totals to SE AK on the
way through the latter half of the weekend.

Aloft, a deep upper level trough across the Gulf of AK has seen
multiple lows and their associated fronts impacting the panhandle
as they swing up from the SE. These systems have thus far been
more wind producers than precip producers, with the most recent
system having largely departed the areas as of early Saturday
morning. In its wake, lingering showers have affected parts of the
northern half of the panhandle, along with some freezing drizzle
around parts of Juneau. These showers will diminish through the
early morning hours on Saturday, and a brief period of drier
weather is expected before the next system rotates into the area
later in the day (and for some locations, the nighttime hours) on
Saturday. This next system will bring with it more rain, more gale
force and small craft winds to various maritime areas, and likely
enough warm air advection to finally mix out the remaining pockets
of cooler air for most locations barring the far northern
panhandle.

Another system will swiftly follow this one, bringing in heavier
rainfall on Sunday and Monday across the area, as significantly
better system dynamics allow for stronger and more organized
frontal bands. The primary changes made to the forecast were some
minor refinements in wind direction and wind speeds for the inner
channels, alongside a delay in warming temperatures for parts of
the central panhandle.

.LONG TERM.../Sunday through Friday/...
Overview: Active weather into the mid range with a series of
strong lows and fronts moving into the AK Gulf from the south.
Expect warm temps, moderate to heavy rain, and strong gusts winds.
Model differences really show up Tuesday into Wednesday depicting
a low tracking towards Haida Gwaii making any forecast from that
point onward uncertain.

Mid level low over the Western Gulf remains in place through
Tuesday keeping that SW flow that keeps moving in the strong
surface lows. Sunday front looking good for storm force winds over
the Gulf and small craft to gale force winds over the inner
channels. Any marine travel Sunday will be difficult at best. With
the main low pulling off to the west overland wind gusts looking
to stay in the 40 to 55 mph range, but occasional gusts of 60 mph
or more not out of the question. Again there are indications of
near record high temps as the warm mid level air moves in so any
precip falling should be rain. And the 24 hour rainfall amounts
upwards of an inch to two inches should be seen Sunday and Monday
with lesser amounts Tuesday.

Mid week onward we are watching for a low tracking up from the
south over Haida Gwaii. GFS as been most aggressive with the
strength, timing, and northern track of this feature. Other
models starting to depict this feature but all much weaker. What
this means for SE AK if this low develops: dryer and bit cooler
weather to the north, windy and warmer with more moderate to
heavy precip for the south again. Beyond mid week, looks like much
of the same with multiple lows tracking in and no real indication
of any cold air or extended weather breaks.

&&

.AVIATION...Flying weather this morning is a lot better than this time
yesterday with the exception of some pockets of freezing rain
where the air mass switches from cold to warm at the surface.
Overall, conditions remain VFR to MVFR for ob sites around SE AK.
The big concern today for flying is going to be the LLWS near the
surface as well as turbulence and icing. LLWS is expected to
increase as the next front moves closer to the region this
morning. Behind the front, LLWS potential is expected to decrease
but there could still be some isolated areas. AAWU forecasts
reflect an increase as well in turbulence and potential for icing
with the higher likelihood for these conditions developing along
the outer coast and offshore water along the front. Closer to
shore, VFR to MVFR CIGs are expected to persist throughout the TAF
period. Although CIGs and VIS are expected to drop as this next
front moves into the area. Conditions then improve briefly as we
see a break before another system moves into the area towards the
end of the TAF period.

&&

.MARINE...Elevated winds continue across the maritime areas, with
gale force winds across the outer coastal waters and small craft
conditions at times across the inner channels expected to last
through the weekend and into the upcoming week.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind late tonight for AKZ317.
     Strong Wind from 3 PM AKST this afternoon through late tonight
     for AKZ323.
     Strong Wind late tonight for AKZ327-329.
     Strong Wind from this evening through late tonight for AKZ328-
     330.
     Strong Wind this evening for AKZ332.
MARINE...Gale Warning for PKZ036-641>644-651-652-661>664-671-672.
     Small Craft Advisory for PKZ012-021-022-031>035-053.

&&

SHORT TERM...GFS
LONG TERM....PRB
AVIATION...SF
MARINE...GFS

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