Area Forecast Discussion
Issued by NWS Anchorage, AK

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14

000
FXAK68 PAFC 151259
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
459 AM AKDT Fri Mar 15 2024

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

A weakening inverted trough is pushing bands of showers through
Prince William Sound this morning. These showers will dissipate in
both intensity and coverage as the trough moves to the eastern
Kenai Peninsula and falls apart later today. The bigger weather
story will be a frontal system moving from the eastern Gulf of
Alaska early Saturday morning to the eastern Kenai and Kodiak
Island coasts late Saturday. This system will bring widespread
precipitation from the Copper River Basin to western Prince
William Sound Saturday. As the front sweeps to the west, a
northeasterly flow aloft will shift southeasterly, allowing
warmer air to advect across Southcentral from east to west. The
warmer air will cause snow levels to rise, first from sea level
to around 1,000 ft by Saturday afternoon, then to 2,000 ft across
eastern Prince William Sound and to near 1,500 ft across the
eastern Kenai Peninsula as a secondary system trails the initial
front with continued moisture and warm air advection.

Cordova will be first to see a transition from rain to snow
Saturday morning, followed by Valdez, Whittier, Seward, and
Portage Saturday afternoon/evening. Moisture will also likely
spill over the Chugach and Kenai Mountains Saturday, with weak
easterly flow aloft initially. Northerly flow near the surface
will keep temperatures west of the coastal mountains colder, with
better chances for all snow on Saturday. Snowfall amounts,
however, look to remain light, on the order of an inch or two for
locations such as Anchorage and Kenai, before a southeasterly
flow aloft strengthens and downsloping develops. Snow amounts in
the western Susitna Valley could be higher. The highest snow
amounts, though, are likely across Thompson Pass and the southern
Copper River Basin, where 8 to 12 inches of snow could fall.

Although guidance diverges with the evolution and track of
successive lows and/or waves, a persistent southeasterly flow
should keep moisture streaming into the Southcentral coast
through Monday. As each low or wave lifts north, a more south-
southeasterly flow should develop for inland locations susceptible
to gap winds - Anchorage, Palmer, Glennallen. Thus, temperatures
are expected to climb above freezing Sunday into Monday. The
bigger uncertainty will be if any precipitation can make it over
the mountains in conjunction with each wave. If so, any snow for
these locations could mix with or change to rain Sunday and
Monday. Specific details beyond early Sunday morning will still
need to ironed out given the model uncertainty, so stay tuned for
forecast updates.

-TM

&&


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

The overall pattern remains largely unchanged as we move into the
weekend. A longwave trough axis extends over Southwest Alaska, an
upper level low resides near the Eastern Aleutians and a front
stretches across the western Bering and Central Aleutians.

Conditions across Southwest Alaska will remain mostly quiet.
Clearer skies will continue through at least early Saturday
morning. High temperatures today and tomorrow across Bristol Bay
and the lower Kuskokwim Valley will be in the teens and low 20`s,
while temperatures in the Kuskokwim Delta will be cooler, with
values in the single digits.

Snow showers and widespread low stratus continue across much of
the Bering Sea, as well as the Eastern Aleutians, southern Alaska
Peninsula and the Pribilof Islands today.

The front extending across the western Bering Sea and Central
Aleutians is producing a band of precipitation, rain/snow, and
areas of small craft and gale force winds, that will persist into
tonight.

There is a chance for precipitation to return to the eastern
portions of Southwest Alaska by Sunday (along the Alaska and
Aleutian Ranges). There is some disagreement regarding a system
moving into the Gulf and precipitation chances and timing will be
dependent on that low`s track.

&&


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

A pair of high amplitude systems control the Alaskan weather
through the forecast period. A well developed upper level trough
over the Bering steers a number of shortwaves and their associated
North Pacific surface systems through the pattern. This will
bring more active weather across the Aleutians into Western
Alaska. A developing ridge expands to cover the Mainland portion
of the state, bringing warmer temperatures across the Interior.

A well developed North Pacific low Monday extends a front over
the Aleutians and moves through the Bering Tuesday and Wednesday
into the Chukchi Sea by Thursday. Gusty winds and locally heavy
precipitation accompany the system over the Aleutians Monday and
Tuesday, and across the Pribilofs late Tuesday into Wednesday. A
second well developed low approaches the Western Aleutians
Tuesday. Its front pushes across the Western Aleutians and Bering
to the Central Aleutians, Alaska Peninsula. Western Alaska and the
Pribilofs by Thursday. Areas along the West Coast of Alaska may
see changes from snow to rain with additional warmth coming up
with the Southerly Winds.

The remnants of a weakening low and front expends its rainfall
over the Copper River Delta through Monday, with snow diminishing
inland through the period. Warmer temperatures pump into the
Northern Interior through Thursday, with some significant daytime
heating expected.


Kutz

&&

.AVIATION...

PANC...VFR conditions and light winds will persist. Cloud cover
increases Friday through Saturday as an upper level shortwave
approaches from the south. This will lead to lowering ceilings
Saturday morning, possible virga over the terminal, and area
showers most likely over high terrain. Confidence is high that
ceilings will remain VFR.

&&


$$


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.