Winter Storm in Alaska, January 12 to 16, 2024

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
215 PM AKST Fri Jan 12 2024

.SHORT TERM...Pattern change in the works for the short range
period as we transition from clear, cold, and dry, to cloudy and
snowy with a gradual warm up through the weekend. We are already
seeing signs of the change with cloud cover and flurries starting
to be observed over the northern panhandle this afternoon.

Through the weekend we will see a series of weak systems move
into the northern panhandle that will produce a long duration snow
event for the northern panhandle and a gradual warming trend. The
first is a weak trough that is just offshore this afternoon and
will gradually move inland through Saturday. Following that is a
weak front for Saturday night and Sunday. Each one of these will
gradually reinforce and intensify the snow that will be falling
over the northern panhandle and NE Gulf Coast. Total snow amounts
and rates are still difficult to pin down exactly as with the cold
air in place over the panhandle. Most of the snow is expected to
start out as dry, granular snow especially over the northern inner
channels that may not pile up as fast. That may gradually change
into wetter and heaver snow by Sat night or Sun especially along
the outer coast as temperatures gradually warm and snow type turns
more dendritic. Currently have issued a winter storm warning for
Pelican as highest snow rates are expected there. Advisories
issued for Yakutat, Gustavus, Hoonah, and Juneau with the highest
snow totals there in the Juneau area. Haines and Skagway will miss
out on the heavier snow as they will be shadowed by the mountains
to the west. Southern panhandle will likely see little in the way
of snow as more offshore low level flow is dominant through the
period there. Temperatures will be slowly warming with
temperatures reaching above freezing for the outer coast and
southern panhandle by Sunday.

As far as winds and seas not much to talk about as neither of the
systems coming in is a prolific wind maker. At most, likely some
25 to 30 kt SE winds along the near shore waters of the gulf
Saturday night into Sunday as the second front moves inland.
Otherwise mostly 20 kt or less for the inner channels through
Sunday. Seas while down to 5 to 7 feet now in the gulf will be
picking up again to around 8 to 10 ft into the weekend as these
system churn the gulf a bit more.

.LONG TERM...Snow showers continue Sunday night into Monday,
moving south. Snow pauses Tuesday bringing a short break from
precip. Uncertainty plagues the long range with different
solutions regarding a surface low south of the AOR. Depending on
low strength and location, we will see different impacts on wind
strength, direction, temperatures, and moisture placement.

Late Sunday night a trough will close aloft and position itself southwest
of the Gulf by a couple hundred miles as snow showers continue to move
south over the Panhandle. As this closed system develops, an accompanying
surface low will deepen, dropping 10 to 12mb in 24 hours. Guidance
continues to struggle with extent and placement of stronger southerly
winds on the northeast quadrant of this system, with the GFS solution
more concerning than the ECMWF ensemble influenced forecast that was
inherited. Have increased winds a touch Sunday night and Monday for
the eastern Gulf and coastal waters, with updates to winds needed as
guidance gets a better handle on the deepening surface low.

While ensembles struggle with location and extent of the robust low, both
show a trend of this feature slowly lifting north into the coast through
the midrange time frame. The GFS keeps the low further west as it
lifts north, with much lighter offshore winds for the Panhandle. Opposite
is the ECMWF, with this solution bringing the low further east before
lifting into the northern Gulf, with widespread low- end southerly
gales to Dixon and much stronger offshore winds from a tighter
pressure gradient. Current forecast reflects a mix of the two
solutions, with lighter winds for most of the coastal environment
and increased easterly winds for Cross Sound starting Wednesday.
Moving through to the weekend expecting to see winds pick up across
the inner channels, with gales or stronger likely in Lynn Canal.

Integrated Vapor Transport into the region remains low, with CW3E guidance
indicating low threat for any significant AR events on the horizon;
however, still expecting a few waves of snow and rain during the
week bringing moderate impacts. While specifics remain unclear,
all guidance continues to bring in warmer air for the south, with
the northern portions of the Panhandle remaining cold.

&&

.AVIATION...Skies continuing to cloud up from the northwest to
southeast. Light snow increasing for the central and northern areas
as front moves in through the evening. Clouds lowering in late
evening with CIR down to 1500 ft. Visibility reduction to 3 sm with
some periods of moderate snow to 1 sm at times. Southern areas
remaining mostly dry for next 24 hours with some mid level clouds
increasing. Snow fall continues for multiple days.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory until 9 AM AKST Sunday for AKZ317.
     Winter Weather Advisory from 6 AM Saturday to 5 AM AKST Monday
     for AKZ320-321-325.
     Winter Storm Warning from 3 AM Saturday to 4 PM AKST Sunday for
     AKZ322.
MARINE...Small Craft Advisory for PKZ022-053-641>644-651-652-661>664-671-
     672.

&&

SHORT TERM...EAL
LONG TERM....AP
AVIATION...PRB

Visit us at http://www.weather.gov/Juneau