Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 241425
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
525 AM AKST Sat Feb 24 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...

A potent shortwave moving over Cook Inlet this morning coupled
with a deepening surface low southwest of Seward are bringing
another round of snow from the Kenai Peninsula north to the
Susitna Valley this morning. A band of heavy snow, with rates of
one to two inches per hour, is lifting northeast away from Kenai
and Soldotna this morning, after dropping a couple of inches
of snow along the Sterling Highway overnight. This band will move
over Anchorage and the Mat-Su Valleys by 6AM with similar snowfall
rates. Anywhere from 2 to 4 inches of snow could fall for these
areas by mid-morning, before the heavy snow bands transition to a
lighter snow.

These bands of heavy snow will also move over the eastern Kenai
Peninsula and into Prince William Sound this morning, with the
highest amounts expected near the Whittier area as the surface low
stalls to the east by noon, then drops south into the Gulf of
Alaska. As the low and attendant shortwave move south, the flow
aloft will shift to the northwest. Lingering moisture over the
Anchorage area will be advected toward the front range of the
Chugach, allowing for persistent snow showers along the Glenn
Highway corridor and Anchorage Hillside through Saturday evening.

In total, a general 2-4 inches is expected for the western Kenai,
3-5 inches for the Mat-Su Valleys, 3-8 inches for the eastern
Kenai Peninsula, 4-8 with locally higher amounts at elevation for
the Anchorage Bowl, and 1-4 inches for Valdez to Cordova.

As the low departs, gusty northerly gap winds will develop. Gusts
to 40 mph or more are possible from Seward to Whittier and Valdez
Saturday night through Sunday. These wind will likely result in
areas of blowing snow during this time, with the Portage and
Whittier areas likely to see significantly reduced visibilities a
times due to resuspended snow. There may also be reduced
visibilities due to blowing snow through Turnagain Pass and
Thompson Pass at times, although confidence in this for Thompson
Pass is low given the one inch or so of expected snow with this
current system.

Following this system another weak ridge will begin to build in
and another wave will be advancing up the southern Gulf of Alaska
pushing over Kodiak Island by late Sunday night/Monday morning. So
this may be a repeating pattern, however it is currently looking
like this ridge building over Southcentral will be a bit more
robust, keeping the worst conditions south of us over the northern
Gulf.

-TM

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days
1 through 3: Today through Monday)...

A broad, longwave upper trough brings deep zonal flow and
continued widespread snow showers to much of the domain. A break
in widespread showery precipitation is anticipated for much of
Southwest Alaska and the central/eastern Bering and Aleutians by
this afternoon as weak mid/upper ridging builds in. By later this
afternoon, a deepening mid/upper level low over the Kamchatka
Peninsula will eject a shortwave towards the western Aleutians,
and an associated surface low will strengthen as it tracks into
the Bering through the weekend into Monday. Precipitation and
elevated winds will first reach the western and central Aleutians
this afternoon before spreading northeastward across the rest of
the Aleutian Chain and Bering through Sunday. As the front lifts
across the Pribilof Islands Sunday morning through Sunday evening,
snowfall combined with winds gusting near 45 mph could lead to
periods of reduced visibilities at times. The front is forecast
to reach the Southwest coast around midnight Sunday/early Monday
morning while the low center follows in tow, tracking over the
Pribilof Islands Monday morning. A swath of westerly winds along
the southern periphery of the low (over the southern Bering in
between the Pribilof Islands and Aleutians) are expected to gust
up to hurricane force Monday morning before diminishing to storm
force gusts by Monday afternoon. As the aforementioned front
reaches Southwest Alaska on Monday, it will bring widespread
steady snow and increased winds. The greatest snow amounts are
anticipated for Bristol Bay as well as the Kuskokwim Delta, and
gusty winds combined with snowfall may produced periods of blowing
snow at times. The low itself will track over Southwest through
Monday and precipitation will become more showery in nature.

-AF

&&


.LONG TERM FORECAST (Days 4 through 7: Tuesday through
Friday)...

There is a lot of model spread by Day 4. A few items can be
gleaned, the Gulf of Alaska will be under the influence of
cyclonic flow but the exact track of the surface low remains
questionable. The global models have also pinged into a surface
low in the Northern Bering. It is a weak feature, but it is
discernible on each global model. There is a dome of high pressure
south of the Western and Central Aleutians. The main feature of
interest and also the main forecast challenge will be the system
in the Gulf Of Alaska. By Thursday, the low in the Gulf of Alaska
is still impacting the region, but there is a new potent low
moving towards the Western Aleutians. Overall, expect a
progressive pattern with the jet stream south of the mainland and
a return of brutally cold temperatures over the Copper River Basin
and the Mat-Su Valley.


&&

.AVIATION...

PANC...VIS expected to remain predominantly IFR this morning (and
likely as low as LIFR by mid-morning) as a band of moderate to
heavy snow moves in. Snowfall rates may briefly approach 1 to 1.5
inches per hour. Snow intensity decreases after noon, with VFR
conditions expected to return by evening. Light winds will persist
through the weekend.

-KC

&&


$$


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