Gale Warning 354, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
502 AM AKDT Tue Apr 2 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:
Today through Thursday night)...

A complex upper level trough stretched out between the western
Alaska Range and northern Gulf coupled with some appreciable
instability in the temperature profile over Southcentral helped
produce a few concentrated clusters and bands of snow (and
graupel) showers overnight. This activity is beginning to slowly
fall apart over the Cook Inlet and Kenai Peninsula as colder,
drier air rushes in from the north and west and as the low levels
also become more stable. This strong cold air advection and
offshore flow is helping to produce fairly hefty gap wind this
morning, with gusts now picking up to around 40 mph near Whittier,
Seward and Kodiak while storm force sustained winds roar through
the Barren Islands.

By later this afternoon, northerly cold advection will cease as
the upper trough moves off into Southeast and is replaced by a
transient upper ridge moving into the southern Mainland ahead of a
powerful low pressure system out over the Bering. Gap winds along
the coast will die off quickly as their support wanes by this
evening into tonight. While it will be fairly chilly in the 20s to
low 30s, some clearing skies and sun are likely to poke out by the
afternoon as dry air aloft moves into place ahead of the
approaching high to the west.

Looking out to Wednesday and beyond, a somewhat more active
pattern will begin to take shape again. By Wednesday morning, the
front associated with the large Bering low will cross the Alaska
Range into the Cook Inlet region. The front will be weakening
fairly quickly as it moves through, but higher elevations of the
Anchorage Hillside, Talkeetnas and Chugach Range could pick up an
inch or so of light snow as the frontal wave passes by on
Wednesday. By Thursday morning, a second front will begin to move
up past Kodiak Island and into the western Gulf ahead of a broad
upper trough approaching the AKPen. While discrepancies for the
progression of this next system remain, most solutions are showing
a new low form over the northern Gulf as the leading shortwave
shifts into Southcentral by Thursday evening. There will be
potential for widespread light snow to spread into much of the
region north of the low, but there is still significant model
spread in terms of how quickly the main upper trough and surface
low lift northeast, and the exact details are yet to be pinned
down. Suffice to say, it may be April, but winter is not going
away just yet.

-AS

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA, BERING SEA, AND ALEUTIAN
ISLANDS (Days 1 through 3: Today through Thursday)...

The forecast remains on track, with only a few minor updates since
yesterday afternoon's forecast package. A strengthening low
approaches the western Aleutians this morning, with ASCAT
scatterometer data showing southerly storm force winds wrapping
around the low. A High Wind Warning remains in effect until this
afternoon for the Western Aleutians as this core of strong winds
moves through. The Western Aleutians could see gusts as high as 85
mph today, with seas as high as 40 feet for the Western Bering
Sea.

The low's front pushes east at a brisk pace, bringing warmer air
and transitioning snow over to rain as it moves across the Bering
Sea/Aleutian Chain and towards Southwest Alaska. As the front
moves into Southwest Alaska later this morning, southeasterly
winds gusting as high as 45 mph combined with the arrival of snow
will cause conditions to deteriorate quickly through the evening,
leading to likely blizzard conditions along the coast from the
Western Capes of Bristol Bay north to Toksook Bay and including
Nunivak Island.

The front pushes inland quickly such that by Wednesday morning,
winds weaken and shift out of the southwest with precipitation
tapering to snow showers as the front continues inland. Then, a
shortwave trough lifts across the eastern Aleutians and Alaska
Peninsula for Wednesday, bringing rain to these regions. As the
trough lifts north, colder air will gradually transition
precipitation to snow, with a rain/snow mix likely for southern
Bristol Bay (including Dillingham) and snow likely for the
Kuskokwim Delta and Valley. Behind the trough axis, continued
upslope flow and cold advection off the Bering Sea will lead to
snow showers persisting along the western slopes of mountains into
Thursday. The southwesterly flow will have a persistent fetch
across the Bering Sea thanks to a large slow-moving low in the
Northern Bering, which may lead to some minor coastal storm surge
impacts on Wednesday/Wed night, with the potential for water to
reach 1 to 2 ft above highest astronomical tide. With shorefast
ice along much of the Kuskokwim Bay coastline, the most
significant impact from this is likely to be some water pooling on
the icepack.

-KC/CQ

&&

.LONG TERM FORECAST (Days 4 through 7)...Friday through Monday

A weakening upper level trough extending from a low over the
Seward Peninsula across the Interior into the Gulf of Alaska
pushes into the Canadian Provinces late Saturday. Arctic air
associated with this low moves over Northern Alaska through the
period. Its surface front slips across the Gulf and dissipates by
Sunday. A Central Bering ridge flattens out over the Western Gulf
by Sunday. A well developed Western Bering low tracks along the
Aleutians into the Gulf of Alaska, slowly decaying through Monday.
This surface system moves swiftly over the Aleutians and Bering
into Bristol Bay for Sunday and crosses into the Gulf by Monday.
Widespread and locally heavy rainfall accompanies the front across
Southern Alaska. Gusty Southwesterly surface winds with areas of
gale force gusts spread Eastward from the Western Aleutians
Saturday, and the Central and Eastern Aleutians by Sunday before
diminishing late Sunday and move out to sea. Gusty Easterly winds
approach gale force across the Northern and Central Bering through
late Sunday. Although Saturday. Areas of minor coastal flooding
North of Bristol Bay to the Yukon Delta are expected. The winds
and precipitation continue across the Alaska Peninsula over Kodiak
Island and the Southcentral portions of the state through Monday.

Kutz

&&

.AVIATION...

PANC...Early this morning snow showers pushed through the area,
leading to prolonged periods of LIFR visibilities and ceilings.
These showers have since weakened and shifted out of the area,
clearing to MVFR and eventually VFR conditions by noon today.
Afterwards, calm winds and VFR conditions are expected to persist
through Wednesday afternoon.

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
155 PM AKDT Tue Apr 2 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0633 AM     Snow             South Anchorage         61.11N 149.86W
04/02/2024  M3.5 Inch        Anchorage          AK   Public

            A member of the public measured 3.5 inches
            of snow.

0833 AM     Snow             Rabbit Creek            61.07N 149.77W
04/02/2024  M0.6 Inch        Anchorage          AK   Trained Spotter

            A trained spotter measured 0.6 inches of
            snow overnight.

0841 AM     Snow             SE Anchorage            61.11N 149.77W
04/02/2024  M0.8 Inch        Anchorage          AK   Public

            A trained spotter measured 0.8 inches of
            snow.

&&