Storm Warning 11, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
241 PM AKST Mon Feb 26 2024

.SHORT TERM.../Through Tuesday night/ Main story of the short
range is the incoming front on Tuesday that will be bringing snow
to a wide area of the panhandle through Tuesday night at least. A
lingering cold air mass over just about all of the panhandle
interacting with the incoming front will be the driver of the
precipitation. It looks like a surface arctic boundary will set
up across the southern panhandle and outer coast from Annette
Island and Ketchikan across Prince of Wales Island and over to
Baranof Island as the front from the gulf moves in. This arctic
boundary will be the focus of the heavier precip and depending on
how it moves (or does not move) will determine what areas get a
lot of snow and what areas receive less. Though just about all of
the panhandle will see some amount of snow, the highest
accumulations are expected around Ketchikan, Prince of Wales
Island, Kuiu Island, and Easter Baranof. The highest rates of
precip are expected Tuesday with a gradual diminishing trend into
Tuesday night and lingering showers into Wednesday.

At the current time Winter Storm Warnings have been issued for
the Southern Panhandle and Outer Coast with Winter Weather
Advisories for just about everywhere else except Skagway, Haines,
and Yakutat. Complicating the forecast is the gusty winds that the
front will be bringing in for the south. Gusts to 30 to 40 mph
are possible Tuesday which could blow the snow around and reduce
visibilities to below one mile at times. We will be on the look
out for blizzard conditions (1/4 mile vis in blowing snow for 3 or
more hours) though it looks to be a low chance at this time. Snow
ratios will also be tricky in that with the cold air in place the
snow may be rather dry and fluffy to start with (around 20:1 snow
ratios or higher), but southern areas could see wetter snow
(around 10:1 or 15:1 ratios or less) as temperatures warm in the
afternoon. Also a few areas (Annette Island, Southern Prince of
Wales, and Sitka) could warm enough Tuesday afternoon that a mix
of rain and snow could be observed rather then all snow lowering
snow totals somewhat.

.LONG TERM.../Wednesday through Monday/...The previous days low
pressure system over the gulf continues its slow track
southeastward while weakening. Showers diminish from north to
south with only the far southern panhandle still under any threat
of snow through early Thursday. Tricky part of the forecast is
that as the low moves in those shower bands there will be a large
differences in accumulation due to terrain and possible training
of showers. In addition the south will warm just above freezing
and that will alter snow ratios. Fro now southern Baranof Island
and western POW have greater chances for a few more inches of
accumulation Wednesday. Elsewhere skies begin to clear and the
northerly and outflow winds increase. Lynn Canal hits upper levels
gale force while other areas will rise to above small craft
levels. Outflow and gap wind areas such as Taku inlet and downtown
Juneau will also see gusts of 40 to near 50 mph. cold arctic air
remains and temps may dip down into the single digits for northern
locations and wind sheltered areas. This pattern lasts into the
weekend when we start to see the next system approaching from the
west. High uncertainty regarding this system and if the front hits
the panhandle. GFS has been more aggressive moving overland while
ECMWF keeps things more offshore. Plenty of run to run
inconsistencies and ensembles pretty much wash out details that
far out. So keeping an eye out on another possible snow event,
followed by airmass change and warming temps.

&&

.MARINE...Widespread higher winds expected in just about all
marine areas starting Monday night into Tuesday as the front comes
inland. Highest winds expected to reach min storm force in the
northern Gulf late monday night into early Tuesday. Gales expected
for the rest of the gulf waters, Clarence Strait, and Southern
Chatham as the front moves east Tuesday. Just about all of the
rest of the inner channels can expect 25 to 30 kt winds except for
the far northern inner channels. Seas will be elevated in the
gulf as well with 20+ foot seas for the northern gulf by late
Monday night. Winds and seas are expected to diminish through
Tuesday night and into Wednesday.

&&

.AVIATION...VFR conditions and breezy weather begins the TAF
issuance with no notable aviation concerns through the evening.
Good flying conditions end in the overnight period as a strong
front approaches from the west. Cold air in place will yield light
and fluffy snow, which yields some VIS concerns. Particularly
along the outer coast and southern panhandle, windy conditions
combined with light and fluffy snow look to bring down VIS to LIFR
conditions for extended periods of time. Not as much moisture
looks to work its way inland, meaning IFR VIS conditions for
areas up to Juneau. Furthermore, windy conditions aloft will
bring LLWS concerns in the aforementioned areas, with winds at
2000 ft approaching a maximum of 50 kt, with the highest winds
around the southern panhandle.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory from 3 AM Tuesday to 5 AM AKST Wednesday
     for AKZ320-321-324>326-329.
     Winter Storm Warning from 3 AM Tuesday to 5 AM AKST Wednesday
     for AKZ322-323-327-328.
     Strong Wind from late tonight through Tuesday morning for AKZ323.
     Strong Wind from Tuesday morning through Tuesday afternoon for
     AKZ325.
     Strong Wind from late tonight through Tuesday morning for AKZ327.
     Strong Wind Tuesday morning for AKZ328.
     Winter Storm Warning from 6 AM Tuesday to 5 AM AKST Wednesday
     for AKZ330-332.
     Winter Weather Advisory from 9 AM Tuesday to 5 AM AKST Wednesday
     for AKZ331.
MARINE...Storm Warning for PKZ644-652-664-671-672.
     Gale Warning for PKZ022-035-036-641>643-651-661>663.
     Small Craft Advisory for PKZ012-013-021-031>034-053.

&&

SHORT TERM...EAL
LONG TERM....PRB
AVIATION...NC

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