507
FXAK68 PAFC 121139
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
339 AM AKDT Wed Mar 12 2025

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

Conditions across Southcentral this morning are, for the most
part, rather tranquil, with widespread low cloud cover , light
winds, and warmer overnight low temperatures than the previous
two nights. The reason for the quiet weather this morning, is that
coastal Southcentral is sitting underneath a col, an area of weak
flow between two upper-level troughs and upper-level ridges. This
area between upper-level features, however, is transient and will
give way to the upper-level trough over the AL-Can border this
morning sliding southwest across the Alaska Range today.

The slow and steady southwestward push of this feature will
provide additional dynamic support by cooling the upper levels
and steepening the environmental lapse rates. Multiple vorticity
maxima dropping underneath the flow and moving from the Susitna
Valley and across Cook Inlet this morning will also aid in
additional lift across Prince William Sound, resulting in the
development of numerous snow showers across the immediate
Southcentral coast and coastal mountains. As of 4am, increasing
shower activity is already evident on radar and satellite imagery.
The cyclonic flow in the mid and upper levels around the trough
is driving the bulk of the showers toward Valdez at the moment.

The multiple vorticity maxima will result in the development of a
surface low somewhere near Seward by this afternoon. As the
upper- level trough slides southwest, the south to southwesterly
flow in the atmosphere will push the low into Prince William Sound
and eventually back to the northwest as the flow aloft backs to
the southeast. This track of these feature will result in shower
activity first over eastern Prince William Sound and the Copper
River Basin today sliding west over the eastern Kenai north the
Talkeetnas this evening. As has been the case with these features,
models continue to struggle with the exact placement and
evolution of these features. As such, where the bands of steadier
snow showers develops, remains difficult to pin down.

Currently, it does look like the heaviest snow amounts will be
from Valdez east across the Chugach Mountains, where 2 to 4+
inches of snow could fall for Valdez and Thompson Pass. Farther to
the east, a drier northerly flow near the surface will also act
to limit snowfall and snow amounts. However, it does look like
there will be a period of snow showers from around Talkeetna south
to the Anchorage Bowl and across the eastern half of the Kenai
Peninsula by this evening. Any accumulations for locations west of
the coastal mountains will likely be light, on the order of a
dusting to less than an inch. However, it is possible that any
training snow showers could result in a quick accumulation snow.
especially along the Seward Highway corridor.

By early to mid Thursday, the overall consensus is that the
eastern Kenai Mountains could see 2-4" of snow out of this system
with flurries to a couple tenths of an inch of snow for the
Anchorage bowl, Wasilla, and Palmer. 2-4+" of snow with the
surface low could extend as far northeast as Valdez (especially
since moisture hangs on longer) and up to an inch for the central
Copper River Basin, dependent on the track of the low.

-TM/AM

&&


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

A large North Pacific low extends its front across the
Aleutian Islands into the southern Bering Sea, bringing easterly
gale force winds and a mix of rain and snow to the islands this
morning. Heavier snowfall has generally failed to materialize in
association with the front, with rain the predominant
precipitation type observed at Adak and Atka and the front now
lifting north of the islands where even warmer air from the North
Pacific, in the mid to upper 30s can begin to impinge on the
central Aleutians today. As a result, have generally warmed up
precipitation types with this front as it continues to progress
into the eastern Aleutians today, bringing initially a rain/snow
mix that transitions to primarily rain by this evening. The front
weakens below gale force today with the exception of a small area
of northerly winds to the west of Adak.

The front will begin to stall out as it reaches the southern
Alaska Peninsula Wednesday night and starts to pivot around a new
low developing south of Sand Point. Precipitation becomes more
showery and changes back over to snow along the Aleutian Chain
through Friday morning as the new low slowly heads towards the
Gulf and colder air moves in across the Bering Sea behind the low.
Friday evening, a stronger front, likely with high end southerly
gales moves into the western Aleutians. The front brings fairly
warm air, so while precipitation may initially start as snow, it
is expected to quickly transition over to rain.

For Southwest Alaska and the eastern Bering Sea, relatively quiet
and dry conditions continue through Thursday with weak high
pressure extending across the region. Clear skies and dry north
to northeasterly flow filtering in from the Interior will also
allow temperatures to cool today and Thursday for Southwest
Alaska. From Thursday to Friday, an upper level low will move
from the eastern Interior to the west coast of Alaska, which
could draw enough moisture north from the Gulf to produce at least
increasing cloud cover, and possibly even areas of light snow
across parts of Bristol Bay and the Lower Kuskokwim Valley on
Friday. Any snowfall that does develop will likely be fairly
light.

CQ/AS

&&

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

A generally unsettled weather pattern covers the Alaska Region
from Siberia to Canada. The main feature across the North serves
as a pathway for low centers to transit from West to East, with a
couple of upper level ridges pushing across the Southern portions.
It all smoothes out to a single extended trough by the end of the
forecast period. A cutoff low in the Gulf of Alaska exits along
the West Coast for Monday. Model guidance is good across the
domain, with some uncertainty with transitory lows South of the
Alaska Peninsula Sunday. The GFS pushes stronger and faster
systems for the new week.

Lingering areas of snow moves over Southwest Alaska through
Saturday. A well developed surface and front pushes locally
moderate rain and gusty winds into the Western Aleutians and
Bering beginning Saturday. Areas of gale force winds develop
closer to the low center as it slips into the Western Bering,
diminishing Sunday. Gusty Easterly winds continue across the
Bering through Tuesday. This system continues an Eastward track
into Southwest Alaska for Sunday, then spreads the locally
moderate rain across Kodiak Island and the Southcentral coastal
zones through Tuesday. Areas of locally heavy rain are expected
along the Eastern Kenai and Western Prince William Sound late
Monday into Tuesday. Back in the Far West, another well developed
low and front approaches the Western Aleutians and Bering late
Monday, repeating the moderate rain and gusty winds for Tuesday.

- Kutz

&&

.AVIATION...

PANC...VFR conditions and light winds out of the north will
persist. The chance for light snow ticks up this afternoon, with
the most likely chance for light snow occurring late this
afternoon into the evening. Ceilings may drop below 5000 ft at
times today, but conditions are generally expected to remain VFR.
Any snow shower activity tapers off Thursday morning to Thursday
afternoon.

&&


$$