Storm Warning 11, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
255 PM AKST Tue Feb 28 2023

.SHORT TERM.../Through Wednesday night/ Significant winter storm
expected to impact just about all of the panhandle during the
short range period as a rapidly intensifying low moves into the
northern gulf tonight into Wed. Winter weather headlines are up
for all of the panhandle with warnings for the NE gulf coast,
northern panhandle, and central inner channels, and advisories for
the southern inner channels and E gulf coast. In addition,
widespread 25 to 30 kt winds in the inner channels, and gale
force (and even storm force) winds, and seas reaching 30 kt for
the gulf are expected with this system.

For the snow, cold air is entrenched in the panhandle right now
which will be overrun by the warmer moist air from the S and SW
tonight and Wed. This precip will come in two pulses. The first
will arrive late tonight as a warm frontal feature, while the
second will be the trailing cold front expected Wed afternoon.
Most areas in the northern half of the panhandle are expected to
remain snow for most of the event and will receive the higher snow
accumulations due to the cold air in place (upwards of 8 to 15
inches). The southern half has the possibility of enough
southerly flow at low levels ahead of the cold front that rain
will start to mix in with the snow which will limit snow totals.
Currently the greatest uncertainly lies from Angoon and Sitka
southward particularly around Angoon, Petersburg, Kake, and
Wrangell. In these areas, southerly flow will try and warm
temperatures up, but snow melt cooling and just the higher precip
rates may keep temperatures cool enough for snow to continue
falling. Decided to error on the side of caution since dew points
are still expected to be rather low which would favor the cooler
and more snow scenario. The precip is expected to switch from
heavy stratiform precip to more convective post front late Wed
night.

As for the marine areas, Winds are expected to increase through
the night with widespread gales and even storm force winds in the
gulf by morning. A second area of storm force winds is expected to
develop over the central gulf Wed afternoon on the south side of
the strong low. It is this second area of storm force winds that
will kick up the seas up to 30 ft across the gulf wed afternoon
and night. This is mainly due to the westerly direction these
winds are coming from which will have a long fetch to build up
seas. Inner channels will mainly see 25 to 30 kt winds Wed with
mainly Clarence and southern Chatham seeing gale force winds.
Winds generally will remain high across the board into Wed night
as strong W onshore flow takes over.

.LONG TERM.../Wednesday Night through Sunday/ A rapidly developing
low in the Gulf of Alaska is expected impact the region with the
heaviest snow accumulation expected Wednesday morning and through
the afternoon. Gale force winds will accompany the front
extending from this feature as it impacts the panhandle early
Wednesday with some areas experiencing storm force winds along the
outer coast as the front approaches. Winds in the inner channels
will also increase to upwards of 25 knots before subsiding through
Thursday night. Winds in the gulf are expected to reach storm
force Wednesday night before beginning to slacken as the low
stalls and progressively weakens over the northern gulf.
By Wednesday night, the heaviest of precipitation is expected to
be over with mostly trailing showers and persistent onshore flow
as the low remains in the northern gulf. Thursday and Friday, most
of the panhandle is expected to see continuing diminishing
showers, shifting to all snow for the southern half of the
panhandle as temperatures continue to drop heading into the
weekend.

Both deterministic and model guidance continue to suggest the low
departing the gulf to the south on Friday, with high pressure
building over the Yukon Territory. Thus the panhandle will once
again be shifting into a northerly outflow pattern with winds in
Lynn Canal reaching gale force Friday night into Saturday. The
gradient associated with this high pressure may shift to be
oriented more East/West, thus leading to winds in the northern
inner channels slackening early next week, but still maintaining
overall outflow.

&&

.AVIATION...VFR conditions with good conditions for most of the
panhandle to start out this TAF issuance followed by worsening
conditions tonight as a strong low moves into the gulf. Already,
multiple pireps from all areas are reporting turbulent conditions. Expect
to see the front move along the panhandle from north to south
with dropping conditions as it moves. Across the panhandle,
widespread IFR and LIFR VIS conditions from widespread heavy
snowfall rates. Along with the low VIS, increased LLWS along and
behind the front is expected, with wind speeds approaching 45 kts
in some areas.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Storm Warning from 6 PM this evening to noon AKST
     Wednesday for AKZ317.
     Strong Wind Wednesday morning for AKZ317.
     Winter Storm Warning from midnight tonight to midnight AKST
     Wednesday night for AKZ318>322-325.
     Winter Weather Advisory from midnight tonight to noon AKST
     Wednesday for AKZ323-328.
     Strong Wind Wednesday afternoon for AKZ323.
     Winter Storm Warning from midnight tonight to 6 PM AKST
     Wednesday for AKZ324-326-327-329.
     Winter Weather Advisory from 3 AM to noon AKST Wednesday for
     AKZ330-332.
     Strong Wind Wednesday afternoon for AKZ330-332.
     Winter Storm Warning from 3 AM Wednesday to midnight AKST
     Wednesday night for AKZ331.
MARINE...Storm Warning for PKZ051-052.
     Gale Warning for PKZ012-035-036-041>043.
     Small Craft Advisory for PKZ011-013-021-022-031>034-053.

&&

SHORT TERM...EAL
LONG TERM....STJ
AVIATION...NC

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Special Weather Statement
National Weather Service Juneau AK
1226 PM AKST Tue Feb 28 2023

AKZ328-282230-
Prince of Wales Island-
Including the cities of Craig, Klawock, Hydaburg, Coffman Cove,
and Thorne Bay
1226 PM AKST Tue Feb 28 2023

A winter weather advisory has been issued for the area. Please see
that statement for more information.