Unalaska, Alaska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

822
FXAK68 PAFC 150207
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
507 PM AKST Thu Nov 14 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:
Friday through Sunday evening)...

The front of a robust low pressure system has moved over the
northern Gulf of Alaska and Southcentral. As the system continues
to overspread Southcentral this evening, precipitation will fill
in the region from Cook Inlet and the Mat-Su Valleys east into
Prince William Sound. With plenty of cold air in place ahead of
the front, precipitation will start as snow for most of
Southcentral, with warmer air moving in for coastal locations, a
shift from all snow to a rain/snow mix is possible. With those
exceptions, Southcentral will see generally snowy weather
overspread the region, with the highest accumulations expected in
the Prince William Sound region. The initial surge of moisture has
started light snowfall in Anchorage, however the winds will
orientate in a more downslope favored pattern later this evening.
Cold and gusty winds are expected to begin accelerating out of the
Mat- Valley into Wasilla around midnight tonight/Friday morning.
There is the potential for a snow shower to have moved through, or
be active in the area at the time of growing winds, which would
be favorable for some areas to see drifting/blowing snow. This
would likely be short duration as winds out of the valley are
expected to come down by early Friday morning.

For Portage Valley and Turnagain Pass, the combination of snow
and wind, at least initially, may produce a period of blowing
snow. Several inches of snow is also possible for Valdez and
Thompson Pass with this system. Snow and blowing snow is also
expected for coastal Western Kenai Peninsula, with the most
impactful conditions expected near Nikiski, with blowing snow
possible south along the Sterling Highway towards Anchor Point.
Multiple Winter Weather Advisories and a Special Weather Statement
are in effect for the Kenai Peninsula and Valdez area. Please see
these products for more information.

Given that the system organizes and pulls into a low pressure
system, precipitation is expected to persist into the early
weekend. By Friday morning, the low is expected to shift the wind
field and allow for a band of snowfall to re-establish from Palmer
to Kenai including Anchorage. This band on the backside of the
low is currently expected to lack a substantial moisture content
but a favorable persistence. This could indicate a potentially
long-duration very light snow event for Anchorage and the
surrounding area from Friday morning into Saturday. Storm snow
totals through Saturday afternoon for Anchorage may reach up to 3
to 5 inches.

-TM/CL

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA, AND THE BERING
SEA/ALEUTIANS (TODAY THROUGH SUNDAY AFTERNOON)...

Here is an update on the products that we currently have out for
Southwest Alaska:

* Blizzard Warning for parts of Kuskokwim Delta north and west of
  the Kuskokwim River, including Nunivak Island. Set to expire at
  4 AM Friday

* Winter Weather Advisory for 6-10 inches of snow along the Lower
  Kuskokwim Valley. Set to expire at 4 AM Friday.

* High Surf Advisory for Togiak Bay coastline. Set to expire at 1
  AM Friday.

Locations along the coastline of Bristol bay, including Dillingham
and Togiak, have transitioned over from rain to snow and will
remain as rain until the late overnight hours. Meanwhile,
blizzard conditions have been experienced in Bethel, Napakiak,
and Nunapitchuk since the late morning hours. While snowfall rates
will decrease as the evening progresses, strong winds will
continue to produce potential whiteout conditions in the form of
blowing snow. The rain/snow line could creep up towards places
like Kwigillingok and Eek as onshore flow persists over the next
few hours, though winds will quickly shift to a northeasterly flow
this evening as the Bering low shifts east towards Bristol Bay.
Storm force winds will persist through midnight for Bristol Bay,
continuing the threat for high surf near Togiak Bay into the
overnight hours.

For Friday, conditions over most of Southwest and the Aleutians
will quiet down as the impactful low moves towards Southcentral
and the Gulf of Alaska. Snowfall will end for most interior
locations by the afternoon, with the exception of mountainsides
due to persistent northerly upslope flow. On Saturday, morning
temperatures will drop below 20 for interior Southwest, with
showery conditions possible over the eastern Bering and Southwest
coastline. As cold air continues to move southward, northerly gap
winds along the Alaska Peninsula and eastern Aleutians are
expected to increase as the day progresses. A weak shortwave will
also pass over the western Bering and central Aleutians Saturday,
though impacts are currently forecast to be limited.

Sunday will be the beginning of a drastic pattern shift to
significantly colder temperatures as an Arctic trough is expected
to dig in over Southwest by the end of the forecast period.
Additional shortwave energy ahead of the trough will allow for
more showery conditions across the eastern Bering and Southwest
coast, with increasing northerly flow aiding in upslope snowfall
for the Kilbuck and Ahklun Mountain ranges. Temperatures will
begin to drop drastically Sunday night, with lows potentially
dropping below zero for interior Southwest.

-BS

&&

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

Monday, the persistent low over the Gulf of Alaska starts to move
off to the southeast, as a ridge high pressure moves into the
region from the west. This high brings much colder temperatures
and clearing skies to South Central and the Copper River Valley on
Tuesday and Wednesday, with temperatures beginning to moderate by
Thursday as the pattern breaks down.

In the west, a ridge of high pressure builds into the Bering Sea
on Monday, expanding eastward into the state through midweek. The
high forces a Kamchatka low northward over the ridge, moving into
northwest Alaska on Thursday, bringing gusty winds and snow to the
region.

-MB

&&.AVIATION...

PANC...Fog concerns around PANC should be over with for the time
being as a front is approaching the area and will likely bring
some light snowfall into this evening. MVFR conditions, with
brief periods down to IFR, are possible in the snow, but snow
should end by midnight and conditions return to VFR. Heavier,
accumulating, snow is expected to develop around 21Z Friday and
bring in IFR visibility and IFR to MVFR ceilings through Friday
night.

&&


$$