Gale Warning 81, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
516 AM AKST Mon Jan 20 2025

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

Monday will bring a brief respite from the otherwise active weather
that's been occurring across Southcentral Alaska in recent days.
Precipitation across the eastern half of the Copper River Basin,
primarily east of the Richardson Highway, will gradually clear out
this morning as the associated trough ejects eastward. Ridging will
then amplify across the area in wake of the system, leading to
generally quiescent weather. Low clouds and patchy fog may be a bit
slow to scour out this morning across the northern Cook Inlet,
portions of Anchorage, and the Mat-Su without a stronger mixing
mechanism, and as light southerly flow carries low-level moisture
into these areas.

Heading into tonight and tomorrow, attention turns towards an area
of low pressure moving towards the southern AK Peninsula, and the
associated front pivoting northward into the western Gulf of Alaska.
A tightening pressure gradient and down-inlet flow will help clear
out any remaining fog/stratus across the Kenai, Anchorage, and Mat-
Su. Simultaneously, widespread small-craft and then gale-force
winds will begin to spread across the Gulf. Model consensus
indicates the front should reach Kodiak Island late tonight and
then the Kenai Peninsula Tuesday afternoon and evening.

This front will bring about many of the same impacts as the last,
though perhaps a bit weaker and quicker moving. Ridgetop winds will
once again be rather strong, with gusts in excess of 60 mph not out
of the question of the Anchorage Hillside and other higher elevation
areas. Precipitation will largely be confined to the typical
windward locations of the eastern Kenai Peninsula and south slopes
of the Prince William Sound and Chugach Mountains. Cooler residual
air and short duration of return flow before the arrival of this front
will likely produce slightly lower snow levels than with the last
couple systems. At this point in time, snow levels look closer to
500 ft, though higher precipitation rates may occasionally drag
snow down to sea level. Turnagain and Thompson Passes will once
again be the 'winners' of this system, with snow amounts expected
to be in the 6 to 12 inch range. Brief periods of 1"/hr rates may
be possible, which would ultimately lead to whiteout conditions /
reduced visibility at times in those locations.

Precipitation will taper off Tuesday night into Wednesday behind the
front, though upslope flow is likely to keep precipitation lingering
along coastal mountains, as well as the Valdez-Thompson Pass area.
The upper-level trough and associated weak surface low will quickly
move eastward across the northern Gulf on Wednesday, bringing
continued unsettled weather over the open water, though additional
impacts inland are not expected at this time.

-Brown

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA AND THE BERING
SEA/ALEUTIANS (Monday morning to Thursday morning)...

An occluded front brings rain to the Aleutians/AKPen, reduced
visibility from snow across the Pribilofs this morning, and snow
for the Southwest mainland tonight into Tuesday. The responsible
low remains south of the eastern Aleutians before crossing the
AKPen Tuesday morning. Warm southerly, low-level flow behind the
front will limit snow to higher elevations, melting snow before it
reaches the ground for lower elevations. Below freezing
temperatures aloft should prevent freezing rain and sleet. This
warm airmass pushes inland toward Bethel, across Bristol Bay and
past Dillingham to Lake Iliamna on Tuesday.

As the main core of the former low passes over the Southwest by
Wednesday morning, cold air wrapping around the back of the system
will move in from the south, dropping temperatures below freezing
north of Dillingham by Wednesday afternoon. Lingering moisture
could produce snow showers north of Dillingham through Wednesday
afternoon.

Meanwhile, in the western Bering, a Kamchatka low is preparing to
send its front sweeping into the Southwest coast by Thursday
morning with widespread gales and areas of storm-force wind. This
may be followed by a long fetch of water vapor and an embedded
low streaming into the region from the North Pacific. This
tentatively appears to be the start a several-day period of
precipitation lasting into the weekend, followed by cold air
sweeping across the Bering Sea which will decisively switch
precipitation to snow by the end of the week. A pattern change
appears to be on the way.

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

Active weather will continue along the south central coast of
Alaska ahead of a large area of low pressure expected to move into
the state from the west around midweek. This low will transit
southwest and south central Alaska by Friday and Saturday and
bring much colder temperatures to most of the state for the
weekend. By Sunday, high pressure will bring drier conditions
gradually building east into the AKPEN and western Kenai by late
Sunday.

&&

.AVIATION...

Fog/mist and drizzle persists through later this morning resulting
in alternating MVFR to VFR conditions. Southerly to southeasterly
winds prevail in the afternoon leading to VFR conditions afterward
and into tomorrow morning. A front arrives tomorrow afternoon
bringing southwesterly wind gusts and VFR conditions.

Preliminary Local Storm Report
National Weather Service Anchorage AK
932 AM AKST Mon Jan 20 2025

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

0742 AM     Snow             Trapper Creek           62.32N 150.23W
01/20/2025  M8.9 Inch        Matanuska-Susitna  AK   Trained Spotter

            Storm total 8.9 inches of fairly wet snow.
            The snow to liquid water ratio was 9:1.
            Temperatures remained just below freezing.
            Currently the snow has stopped.

&&

AS

Preliminary Local Storm Report
National Weather Service Anchorage AK
935 AM AKST Mon Jan 20 2025

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

0837 AM     Snow             5 E Valdez              61.11N 146.22W
01/20/2025  M9.0 Inch        Chugach            AK   CO-OP Observer

            Updated total snowfall since yesterday
            morning. Total snow water equivalent of 1.64
            inches. Mix of rain and snow turned to heavy
            wet snow overnight.

&&

AS