Gale Warning 50, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
546 AM AKST Sun Jan 12 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Today
through Tuesday night)...

Key Points:

* A major winter storm is impacting Southcentral Alaska, the Gulf
  coastal waters, and Kodiak Island. Dangerous winds and heavy
  precipitation from this storm will persist through the morning
  hours, with some improvement for most of the region as we
  continue through the remainder of the day.

* Gusty winds will persist all the way through Monday morning
  before dying down Monday afternoon.

* Temperatures will remain above freezing for most of Southcentral
  through Monday, then drop down below freezing Monday night.

* The week ahead looks more "normal", with cooler temperatures and
  multiple chances for snow.

Satellite imagery shows a very large and impressive storm system
impacting nearly all of Alaska. The low is tracking northward into
the eastern Bering Sea, with a very strong frontal system
progressing out from the low center toward southern Alaska. A
strong upper jet stream and atmospheric river are supporting heavy
heavy precipitation from Kodiak to the eastern Kenai peninsula
and Prince William Sound region. The significant warm air
advection with the front has not yet arrived in these areas. As a
result, the precipitation intensity has helped drag the snow
level down to sea level, with snow being reported in places such
as Whittier, Valdez, and much of the Seward Highway corridor
across the eastern Kenai Peninsula. Warmer air will arrive at the
eastern Kenai Peninsula within the next few hours, leading to a
transition to rain for lower elevations. The rain on snow covered
roads will contribute to hazardous travel conditions.

Meanwhile, dangerously high winds have been observed ahead of the
frontal system. Most impressive have been the winds in Anchorage,
where winds have been strong and erratic, with wind directions and
speeds frequently changing over short periods of time. This is
indicative of mountain waves, which have been the focus of the
forecast and decision to issue High Wind Warnings. The highest
wind gust thus far was 110 mph in Bear Valley. Gusts of 75 to 85
mph have been frequent across the Anchorage Hillside. At lower
elevations of Anchorage, winds have peaked at 40 to 60 mph thus
far.

The worst is not quite over. As the front continues to approach
Southcentral this morning, winds will strengthen along the north
Gulf coast into the Prince William Sound region. High winds will
continue in the Anchorage area through about mid morning before
starting to let up just a bit. Winds will also continue to
increase in the Matanuska Valley this morning. The occluded front
will push onshore and rapidly weaken around Noon today. At this
point, winds will diminish well below peak values, but remain
strong and gusty across most of Southcentral and the Gulf.
Precipitation intensity will also diminish a bit along coastal
areas, but precipitation will continue through Monday morning as
a series of upper level short-waves move through. Upslope flow and
instability as cold air aloft advects into the region tonight
into Monday will lead to locally heavy showers at times. A shift
in wind direction to the south will allow showers to progress
inland. As the colder air moves in, snow levels will drop and
precipitation will transition from rain to snow.

Impacts from this storm will finally wrap up Monday afternoon,
with winds and precipitation largely ending. A series of weaker
storms and upper level troughs will track up from the Pacific this
week and affect Southcentral and the Gulf. Confidence in the
details of these is low to moderate. However, what can be said
with confidence is that there will be a return to more "normal"
winter time weather with cooler temperatures and a good chance of
snow for most of the region.

-SEB

&&

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

A large storm-force low pressure system in the eastern Bering Sea
is producing gusty easterly winds across Southwest Alaska, with
the strongest winds exiting through Kamishak Gap into the greater
Bristol Bay region this morning. Rain and snow has also moved
back across much of the area as well. Northerly gale force winds
across the Pribilof Islands and eastern Aleutians are bringing in
a colder air mass from the western Bering Sea, leading to blowing
snow reducing visibility to near one mile. Temperatures remain
above freezing which is limiting the potential for visibility
reduction, but cooling temperatures later this morning may allow
visibility to drop as low as one-half mile. Winds diminish over
the next several hours across Southwest Alaska, but winds remain
enhanced across the Bering Sea/Pribilofs through this afternoon
before diminishing and shifting westerly.

Light to moderate snowfall over Nunivak Island and for the
Kuskokwim Delta coast north of Kipnuk will allow for several more
inches of accumulation through the morning hours before
precipitation tapers off to showers. Sustained winds of 30 to 35
mph along the coast is also leading to blowing snow this morning.
With winds expected to diminish over the next several hours, the
blowing snow threat will quickly diminish. Blowing snow may make a
return this evening as the Bering low lifts northward, bringing a
push of southwesterly winds and renewed snow showers. However,
current thinking is that snow intensity will be too light to lead
to visibilities as low as one half mile for any sustained period
of time. The showery nature of precipitation may also contribute
to limiting the threat.

Southwesterly winds contribute to continued coastal flooding
potential, with a Coastal Flood Advisory remaining in effect for
the Kuskokwim Delta coast, particularly between Kipnuk and
Kwigillingok coincident with high tide today and Monday evenings.
An additional High Surf Advisory has been issued as the strong
onshore push of winds through Bristol Bay will bring elevated
water levels there as well for high tide this afternoon and early
Monday morning. The main threat with this is likely to be high
surf and potential for coastal erosion along the Bristol Bay
coast.

Out west, a compact gale-force low tracks near the western
Aleutians. With a cold air mass moving into the western Bering
Sea, there is also potential for blowing snow for those islands
this evening through Monday morning, however the showery nature of
precipitation will likely make visibility reductions below one
mile intermittent. The cold air mass spreads across the Bering
Sea and into Southwest Alaska with the northward exit of the large
low Sunday night, dropping temperatures into the 20s for Monday
and into the teens Monday night. Expect this colder air mass to
also bring drier conditions across the region as well for the
beginning of next week. The gale force low over the western Bering
tracks into the northern Bering for Tuesday, spreading snow
showers as far as the Pribilof Islands.

Quesada/Eovino

&&

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

On the Alaska Weather map, an elongated upper level trough
stretching from the Russian Far East across the Aleutians and
Bering. This trough gets a little boost from passing shortwaves to
reorient over Southwest Alaska and the Gulf of Alaska for
midweek, before continuing its Eastward track into Canada by
Thursday. An upper ridge building across the Western Aleutians
Tuesday moves to extend across the Gulf of Alaska and Western
Alaska into Northeast Russia through the end of the week.
Deterministic GFS and ECMWF carry the features and changes well
through Thursday with the Canadian models joining up into the
weekend.

A decaying surface low on the Southcentral coast spreads locally
heavy rains along the coastal locations, with locally heavy snow
further inland and over higher elevations through Wednesday. A
second low over the Shumagin Islands brings mostly rain with snow
over Bristol Bay from the Eastern Aleutians, Alaskan Peninsula and
Kodiak Island through midweek, before moving over the Kenai
Peninsula before dissipating over Prince William Sound Thursday.
Bands of snow progress across the Bering through Thursday. A well
developed North Pacific low and fronts spreads snow changing to
rain across the Western and Central Aleutians Wednesday and
continues over The Bering, Southwest Alaska and the AKPEN by
Friday. Gusty winds with gale force gusts work their way from the
Central Aleutians over the AKPEN and Bering through Friday.

&&

.AVIATION...

PANC...The big story for the TAF forecast remains significant
winds. Mountain waves coming down the Chugach Mountains have led
to strong and erratic winds overnight. This will continue until
frontal passage, which is roughly around 18Z. Then expect the
Turnagain Arm jet to bend into the terminal and winds will become
more consistent out of the southeast. Winds will diminish this
evening as pressure gradients slacken, but then strengthen again
out of the south overnight tonight into Monday morning as cold air
advection moves up Cook Inlet.

VFR conditions will prevail through this afternoon due to the
strong southeast flow across the mountains. The low level flow
will then gradually veer toward the south this evening, leading
to lowering ceilings. Weak upper level short-waves will cross the
region tonight through early Monday and combine with instability
to produce showers. This could lower ceiling/vis to MVFR at
times, though think the gusty winds will largely keep ceilings
above 3000 feet most of the time.

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
107 PM AKST Sun Jan 12 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1116 AM     Rain             1 S Crown Point         60.42N 149.37W
01/12/2025  M2.70 Inch       Kenai Peninsula    AK   Public

            Corrects previous rain report from 1 S Crown
            Point. 2.7 inches since midnight, non stop
            but varying intensity. Temps btwn 33.4-35.6
            and precip switches to heavy wet snow/mix
            occasionally but mostly rain. Our
            semi-sheltered weather station has max gust
            of 22 mph at 6am but nearby Kenai Lake RAWS
            shows 33 mph. No downed trees or damage from
            wind, but report of one tree in highway
            nearby earlier. Approx 1 inch of slush and
            areas of pooled water in yard.

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
108 PM AKST Sun Jan 12 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1229 PM     Tstm Wnd Dmg     1 E Chugiak             61.40N 149.45W
01/12/2025                   Anchorage          AK   Public

            Trees down.

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
111 PM AKST Sun Jan 12 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1138 AM     Non-Tstm Wnd Dmg 1 SE Eagle River        61.31N 149.54W
01/12/2025                   Anchorage          AK   Public

            Broken tree in yard, small branches breaking
            off consistently. Rain/snow mix along with
            strong winds.

&&

CL

Preliminary Local Storm Report
National Weather Service Anchorage AK
117 PM AKST Sun Jan 12 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1215 PM     Non-Tstm Wnd Dmg Anchorage (South Additi 61.21N 149.91W
01/12/2025                   Anchorage          AK   Public

            Downed tree on truck and blocking roadway.

&&

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Preliminary Local Storm Report
National Weather Service Anchorage AK
204 PM AKST Sun Jan 12 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1223 PM     Non-Tstm Wnd Dmg 1 E Eagle River         61.32N 149.53W
01/12/2025                   Anchorage          AK   Public

            Branches down. Flags torn. Roof flashing
            torn. Plant pots overturned.

&&