Brisk Wind Advisory 29, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
504 PM AKST Tue Feb 27 2024

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

A storm-force low continues to drift southeast across the Gulf of
Alaska this afternoon. Gusty winds across Cook Inlet are expected
to increase through tonight as colder air advects from the north
and a strong surface high pressure develops over the interior. For
coastal locations, gusty gap winds persist and will continue to
increase in intensity Wednesday into Thursday. Winds are likely to
gust in excess of 50 mph for Seward and Valdez beginning
Wednesday, with Thompson Pass, Whittier and Kodiak City
potentially seeing winds gusting over 60 mph. For areas farther
inland, including Anchorage and portions of the Mat-Su Valleys,
winds could gust in excess of 30 mph beginning late Wednesday.

The biggest challenge in the short term will be where
temperatures bottom out by Thursday morning. For locations removed
from the gusty winds, temperatures will easily fall between -10F
and -20F, and likely close to -30F, in the Copper River Basin. For
areas experiencing gusty winds, mixing near the surface may
inhibit deep inversions, and very cold temperatures, from
developing. Still, temperatures in the 20s along the coast will
slowly drop toward the single digits by Thursday with windier
interior locations seeing temperatures in the teens falling to
between 0 and -10F.

For many locations across interior Southcentral, winds chills
could fall between -20 and -35F, with the coldest values in the
Northern Copper Basin and across the Susitna Valley. Through
Thompson Pass, Broad Pass and Isabel Pass, wind chill values
through could fall to -40F by Thursday morning.

This cold airmass looks to remain in place through Friday. By the
weekend, models diverge on whether this unseasonably cold air
persists or begins to retreat as a frontal system approaches from
the west.

&&

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

The weather pattern is in a slight lull as most of the active
weather producers have moved out of the area. This has left
Southwest Alaska to clear and dry out with a definitive shift
toward cold, dry northerly air. These colder temperatures in
conjunction with the departing low pressure system to the
southeast of the Alaska Peninsula will create gusty winds across
the Alaska Peninsula tonight. Storm force winds in the marine
areas on the southern side of the Peninsula will kick up this
evening, returning to gale-force through the day Wednesday.
Further north for mainland Southwest Alaska, temperatures will
continue to grow increasingly colder the next few days. Persistent
and gusty northerly winds will create ideal conditions for low
wind chills, with the Lower Kuskokwim Valley to see the worst of
conditions. Wind chill values in this area will be lowest in the
very early morning hours of Wednesday, Friday, and particularly
Thursday when wind chills may reach as low as -50 degrees F. Skies
will be mostly clear over Southwest Alaska for the remainder of
the workweek, allowing for the temperatures to recover slightly
during the day due to solar heating, but will similarly heighten
the cooling overnight. As such, a Special Weather Statement has
been issued for Southwest with regards to the cold temperatures,
please see that for more information.

By later tonight into Wednesday, a small polar low is expected to
form near or just south of the ice edge out to the west of Saint
Matthew, then track southeast towards the Pribilofs during the
day on Wednesday. Depending on the exact track of this feature, a
brief period of winds gusting as high as 40 to 50 mph along with
snow and blowing snow will be possible for the Pribilof Islands as
the polar low brushes past just off to the north. The low will
then dives into the southern AKPen by Wednesday evening as it
begins to lose integrity, with an uptick in areas of snow again
possible along the southern AKPen and out to Dutch Harbor late in
the day Wednesday.

Further west, a north Pacific low pressure system will swing a
pronounced warm front into the westernmost Aleutians beginning
Wednesday morning. Along the initial frontal push, widespread snow
and gusty winds out of the southeast will begin in Shemya and Attu
by Wednesday morning. Behind the front, very warm air well above
freezing will move in which will allow snow to quickly change over
to rain between Adak and Shemya on Wednesday afternoon as the
boundary lifts north into the southwestern Bering. The front will
continue to slowly shift northeast on Thursday, bringing returning
chance for precipitation to the Pribilofs and eastern Aleutians.
There are some early indications that warm air aloft may begin to
overrun the frigid air mass slowly retreating east at the surface,
and this could allow a mix of snow, sleet and freezing rain to
develop along a transition zone ahead of the front. The eastern
Aleutians and Pribilofs will have the best chance to see this
wintry mix materialize as the front approaches from the west late
on Thursday.

-CL/AS

&&

.LONG TERM FORECAST (Days 4 through 7) Saturday through Tuesday...

Model tracks and strengths become more uncertain through the
forecast period. The weather pattern across the region is
dominated by moderately high amplitude troughs and ridges
traveling from West to East. A strong upper level trough over the
Central and Eastern Interior exits into the Canadian Provinces for
Sunday. On its heels is a upper level ridge that moves into the
Mainland by Tuesday. This draws a considerable amount of subzero
Arctic air all the way down to Southcentral and Southwest Alaska
through the weekend. Gusty outflow winds are expected along the
Southcentral coast and through Bristol Bay on Saturday.

In the West, a fairly strong low enters the Western Bering on
Sunday and tracks across the Northern Bering through Tuesday.
Widespread gusty winds with areas of gale force gusts spread over
the Southern Bering and Aleutians, diminishing late Monday, before
a second developing low approaches the Western Aleutians for
Tuesday. This low will bring another round of widespread gusty
winds with areas of gale force gusts spread over the Southern
Bering and Aleutians late Monday into Tuesday. Both lows deliver
locally heavy precipitation through Tuesday.

Kutz

&&

.AVIATION...

PANC...VFR conditions will persist. Northerly winds will be the
story from this evening through the next few days. The strongest
winds look to be Wednesday afternoon and evening when gusts could
reach up to 35 kt.

&&