Gale Warning 123, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
538 PM AKST Sun Feb 5 2023

.ANALYSIS AND UPPER LEVELS...

The pattern remains amplified across the North Pacific. An upper
level low currently extends across the Bering Sea and is slowly
moving eastward. An upper level ridge extends across the west
coast of Canada. Closer to the surface, radar and observations
shows snow moving across the Kenai Peninsula and a mix of rain and
snow in Prince William Sound. Observations show rain and
temperatures in the mid to upper 30sF across Kodiak Island.
Observations show snow across Bristol Bay and snow showers across
the Kuskokwim Delta.

&&

.MODEL DISCUSSION...

Guidance is in good agreement with the placement and intensity of
synoptic scale features. The biggest challenge continues to be
resolving small mesoscale local effects. Forecast confidence
overall is above average.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist. Vicinity snow
showers will continue through 06th/14z.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:
Sunday night through Wednesday night)...

A strong low is pushing over the northern half of Kodiak Island
this evening. This low has been producing storm force winds with
gusts to 65 knots observed near Augustine Island. Elevated winds
are expected to continue around the low through the evening hours
and also in association with a front overspreading the Kenai
Peninsula. Winds should diminish by or just after midnight as the
front and associated low finally begin to weaken. Onshore of the
coast, the combination of snow and gusty winds is contributing to
poor visibility through Portage Valley and Turnagain Pass.
Afternoon observations have shown visibility down to less than one
half mile at times and a winter weather advisory for blowing snow
remains in effect through 9pm this evening from Portage Valley to
Turnagain Pass. While winds are expected to taper off through
tonight, poor visibility from snow and blowing snow may persist
through the morning hours. Total snow accumulations of 8 to 14
inches remain forecast for the advisory area with local amounts as
high as 20 inches possible near the Whittier Tunnel. Elsewhere,
blustery conditions are also ongoing across Thompson Pass.
Forecast models continue to trend upward with snow amounts for
Thompson Pass, which could see a foot of snow through tomorrow,
especially for northern Thompson Pass. Hazardous travel conditions
will be present through the overnight hours with slick roads and
reduced visibility expected.

On Monday snow will finally return to the Anchorage Bowl and
Mat-Su as a strong southeasterly flow over the Chugach Mountains
finally weakens and allow some moisture to reach the surface.
Snow is forecast to increase in coverage across the Anchorage Bowl
during the morning hours, potentially during the morning commute,
before peaking by midday. Modest snow amounts of 1 to 2 inches
are forecast, though some locations, especially on the Hillside,
could see higher amounts closer to 3 inches through Monday
afternoon.

Through the rest of the week transient high pressure is expected
to materialize over Southcentral, which should lead to drier
conditions inland of the coast, with a gradual cooling trend
through Wednesday night.

&&

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

The primary weather maker today is a strong low currently north
of Kodiak Island that is spreading snow over the Aleutian Range
and into Bristol Bay. Gusty northerly winds in response to the low
have resulted in blowing snow in the low lying areas of Bristol
Bay, which should come to an end by 7pm when the winds relax.
Influence from this low will abate tomorrow, but a quasi-
stationary upper level low will keep some areas from Bristol Bay
north into the Kuskokwim Valley in light snow through Tuesday.
Expect temperatures to gradually fall over the coming days as cold
air continues to stream in from the north.

&&

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

Broad northerly winds and brief, but heavy snow showers will
linger across the Bering and Chain through Monday evening as a
complex low with multiple centers weakens and moves east.
Starting Monday night a series of compact, yet moderately strong
lows will move across the chain, bringing localized areas of gales
and rain/snow showers. Over the water, areas of extreme freezing
spray are possible near the ice edge from Cape Newenham to near
St. Matthew Island. Expect temperatures to remain near freezing.

&&

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

Confidence continues to remain high on both domains remaining
rather active with no real sustained quiet stretches with high
pressure firmly in control, but rather transient ridges between
systems; the only exception might be coastal southwest Alaska.
Southern Alaska still remains under the influence of a broad
negatively trough. Expect more  precipitation for the eastern
Kenai Peninsula, Prince William Sound, the northern Gulf Coast, as
well as interior southwest Alaska. The western Kenai Peninsula,
Anchorage, Mat-Su Valleys, and Copper River Basin could also see
precipitation chances during the first half of the longterm as
well, but uncertainty exists with potential cross barrier flow
issues. The models converge on the idea of a return to unsettled
weather as a deep Bering Sea low sends multiple fronts and
shortwaves eastward into the coast through at least Saturday. By
Sunday, there is a lot of model divergence at the surface, but the
consensus is that the longwave trough will continue to influence
the region.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...ED
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CJ
LONG TERM...PJS