Gale Warning 102, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
437 PM AKST Fri Jan 28 2022

.ANALYSIS AND UPPER LEVELS...

A vertically stacked low near Kodiak Island is continuing to
drive snowfall along the coast in southeasterly flow out ahead
of it. Despite the widespread radar returns, much of the
precipitation farther inland is not reaching the ground. Heaviest
precipitation is seen near Prince William Sound and will gradually
taper off through the evening as the low tracks eastward over the
Gulf. Farther west, gusty winds are occurring south of the Alaska
Peninsula in northwesterly flow behind the aforementioned lows.
These will also diminish through the evening. Otherwise the only
other feature of note is a compact low in the far western Aleutians.
Strong southerly winds ahead of it are bringing rain to Adak.
Benign conditions are observed elsewhere across the rest of the
Bering/Aleutians in a weak flow pattern.

&&

.MODEL DISCUSSION...

As a low begins to track eastward in the Gulf this evening, there
remains some model disagreement as to how it will merge with
another circulation tracking northward in the eastern Gulf. In
any case, impacts to the coast will be the same, with snowfall
gradually tapering off into Saturday morning. The strength and
position of a low in the far western Aleutians is well-handled.

&&

.AVIATION...

PANC...VFR ceilings are likely to persist, although brief MVFR
ceilings are possible through this evening. Little to no
precipitation is expected.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 to 3: Tonight
through Monday):

An upper level low near Kodiak Island will continue to sink
southeast into the Gulf through Sunday morning, with its
attendant surface low pressure wobbling across the gulf towards
the AK Panhandle. What's left of the snowfall event will end for
most locations by early tomorrow morning as the low pulls away
from the coast, with initially easterly flow around the low and
downslope drying preventing any remaining snow from reaching the
ground across the Mat-Su Valleys tonight. In contrast, areas west
of Prince William Sound still seeing moderate snow with upslope
enhancement could see several more inches of snowfall before the
low shifts farther into the Gulf, with locally up to another foot
possible near Turnagain Pass and Portage Valley through late
tonight.

Overall quiet and slightly cooler conditions will prevail for the
rest of the weekend into early next week as dry offshore flow
develops around an upper level ridge moving into the western half
of the state. The coldest and densest air will pool into the
Copper River Basin, helping to drive gap winds through namely the
Valdez Arm, Thompson Pass and Copper River Delta for the next few
days. These winds are not expected to be anything out of the
ordinary, with the main Gulf low departing to the east by tomorrow
night and consequently decreasing support for a stronger pressure
gradient along the North Gulf Coast. Otherwise, expect a good
chance for some sun to return as early as Saturday afternoon with
the drying flow from the interior helping to gradually clear out
the overcast skies currently in place. Temperatures will cool
somewhat to the 10s to 20s for highs and single digits for lows
for most areas away from the coast through Monday, except over the
Copper River Basin, where lows well below zero are possible both
Sunday and Monday morning.

&&

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

Southwest will see cooler temperatures as we move into the weekend.
Northeasterly winds will be prevalent but mild thanks to an upper
low situated along the Gulf coast. This low is forecast to amplify
westward into Bristol Bay on Saturday as a shortwave trough over
central Alaska digs southwestward into the Bering and a ridge of
high pressure over the Bering shifts northward and over arctic
Russia. Ultimately this should maintain light northeasterly winds
and generally clear conditions into Saturday for much of Southwest.
Winds across the Alaska Peninsula and interior Bristol Bay,
however, will see north to northwest winds as the surface flow
wraps into the departing upper low over the Gulf. Sunday will see
little in the way of impacts as weak height rises briefly overspread
Southwest, which could result in slightly warmer temperatures by
a couple of degrees. Into Monday, however, a pattern change may
commence with the arrival of front into the Kuskokwim Delta and
Bristol Bay. Precipitation chances will return to the coast by
late Monday along with a chance for a wintry mix.

&&

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

A cold air mass over the Bering will begin to vacate northward
over the next 24 hours as a weak upper low moves toward Kamchatka.
In the short term this low is producing scattered showers and
overcast skies for much of the Western and Central Aleutians.
Winds on the leading edge of an occluded front may gust to storm
force at times from Attu Station to north of Adak with widespread
gales anticipated across the western Bering. Also in the short
term and further east, northerly gap winds gusting to 50+ knots
will remain possible through the bays and passes of the Alaska
Peninsula into tonight before tapering off during the morning
hours on Saturday. An ASCAT pass from this afternoon revealed 50+
knot winds south of Chignik which should persist through tonight.

A new North Pacific upper low will begin to approach the Aleutian
Chain late on Saturday with scattered showers for the Central
Aleutians. Shower activity is expected to expand in coverage by
Sunday as the low brings a front across the Aleutians and into the
Alaska Peninsula Sunday into early Monday. While snow cannot be
ruled out, it looks like rain will become the predominant
precipitation type as a strong southerly push of warm air follows
in the wake of the front. By Monday the upper low and its
associated front are forecast to depart the Bering to the north.

&&

.MARINE (Days 3 through 5 - Monday through Wednesday)...

Gulf of Alaska:

High pressure exits the Gulf for Tuesday. A front enters the
Western Gulf Tuesday and extends across the Gulf by Wednesday.
Forecast confidence is good. Southerly gales are likely as the
front cross the Gulf, particularly in the barrier jet locations
along the north Gulf coast as well as in the Barren islands to
Kamishak Bay area. These stronger winds look like they will be
brief, diminishing by Wednesday.

Bering Sea/Aleutians:

Expect an active weather pattern across the Bering Sea and Aleutians,
with multiple storms tracking from the Pacific northward across
the Bering Sea. Forecast confidence in the specific track of each
storm is low. However, confidence is high in a long duration of
gale force winds across the region. There is also potential for
smaller areas of storm force winds near the low centers. Seas will
remain elevated above 20 feet for the much of the three day period.

&&

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

A robust blocking pattern dominating the Gulf will remain in place
in spite of multiple long-wave troughs from the Bering riding
along the high trekking through the Southwest and Southcentral
through the long term. These waves could bring increased clouds
and potentially light snow and a wetter regime over the area. As
the ridge axis settles across the state beginning Wed morning,
dry conditions and rising temperatures are expected for both
Southwest and Southcentral. Though precipitation type issues may
become a challenge, the presence of the upper ridging could help
minimize unstable energy lurking farther inland of Southcentral by
Fri and Fri night.

Over the Bering/Aleutians, a gyre complex North Pacific low will
usher stronger winds with periods of higher gusts along the gaps
and passes starting Tue afternoon through Wed night. Another North
Pacific low races through the central Aleutians bringing more
tropical moisture and stronger winds there and Pribilof Islands
into Fri afternoon. Warm temperatures associated with the
aforementioned lows will produce rain/snow mixed over much of the
Bering/Aleutians through the end of the week. Model solutions
struggled quite a bit with the wind coverage of the latter low,
but clearly points out similar tracks as the low pushes north of
the southern Bering Fri morning.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning 130 131 150 155 174 175 176 177 178 185.
 Heavy Freezing Spray Warning 130 138 150 155 165 179 185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...AP
SOUTHCENTRAL ALASKA...AS
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...BL
MARINE/LONG TERM...CB