Gale Warning 309, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
524 AM AKDT Fri Apr 11 2025

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

Discussion:

The system that brought periods of moderate to heavy snowfall across
portions of the Kenai Peninsula, Prince William Sound, and the
Anchorage Borough is finally trying to wind down as the upper trough
ever so slowly creeps northwards across the northern Gulf. The
surface low is currently moving into the upper Cook Inlet/Turnagain
Arm and will continue to weaken as it moves towards the Susitna
Valley. With the surface low in the vicinity, and still quite
unstable in the mid-levels, moderate snow showers continue to
develop along the Turnagain Arm and move down the Arm and over the
Anchorage Bowl. Overnight temperates in the lower 30s have allowed
any snowfall that fell last night to stick to area roads, so expect
another slushy drive for the morning commute. As such, the Winter
Weather Advisories will remain in effect this morning until
conditions improve and/or they are allowed to expire. Further east
towards Portage, Whittier, and Turnagain Pass...moderate to heavy
snowfall overnight allowed for some modest snowfall accumulations as
of early this morning. Conditions for these areas have improved as
heavy snow has come to an end; however, scattered showers are
possible through the day today. The upper trough finally moves
inland by early this afternoon with shortwave ridging building into
Southcentral Saturday.

Looking ahead... A strong low will dive southwards across the Bering
Sea and merge with a low moving up towards the AKPEN from the North
Pacific. As the North Pacific low rotates up across the AKPEN, a
stout pressure gradient will form over Kodiak Island to the southern
Kenai Peninsula bringing widespread gales to the northern Gulf. Gale
to storm force winds are expected to develop through the Barren
Islands and Kamishak Bay with strong winds also developing over the
southern tip of the Kenai Peninsula. Seldovia could see wind gusts
of up to 50 mph Saturday night. As the front lifts north,
precipitation will once again move into coastal Southcentral.
Precipitation might start out as snow for most locations with a
change-over to rain as warmer temperatures move in.

- PP

&&

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

Two lows bring impactful weather across much of the Bering Sea and
Southwest Alaska from through Sunday afternoon. There is still
some uncertainties with the track of these lows that has created
difficulties pinpointing hazardous conditions. The Winter Weather
Advisory for Nunivak Island and the Kuskokwim Delta coast remains
in effect starting this morning and persisting through Saturday
morning. For mariners, confidence is also high that heavy to
extreme freezing spray is likely along the sea ice edge in the
Northern Bering. A weak surface low southwest of Saint Matthew
Island will rapidly strengthen as it moves towards Nunivak Island
through this morning. This low will bring snow and gusty winds to
Nunivak Island and the Kuskokwim Delta coast. With temperatures
remaining much below freezing, confidence is high that these
conditions will bring blowing snow and visibilities reduced to
one-half mile or lower at times, hence the advisory in effect for
this area.

There is lower confidence regarding the potential for blowing
snow for the Pribilof Islands. With roughly a 120 mile difference
between the farthest southeast and northwest model solutions for
the aforementioned low, there are two possible outcomes for late
Friday night/Saturday. With a further east solution, the Pribilof
Islands could see gusty northeasterly winds, snow and blowing snow
with visibility reductions to one-half mile or less. A further
west solution would put the core of strongest winds offshore,
lessening the chance for blowing snow, though snow showers are
still likely to occur.

For the Eastern Aleutians, there's potential for the compact low
to cause significant visibility reductions in blowing snow from
Saturday afternoon through Saturday evening, though the strongest
winds will likely remain west of Unalaska. From late Saturday
night through Sunday, a low curving south from Bristol Bay could
also bring hazardous blowing snow conditions, though the Eastern
Aleutians will sit at the periphery of the impact area. If this
low's track stays where models currently have it, the worst
conditions will likely occur along the southern tip of the Alaska
Peninsula instead.

With impactful weather forecast but lower confidence in the
details, please stay tuned as we continue to update and refine the
forecast.

-Chen/Mitchell

&&

.LONG TERM FORECAST (Days 4 through 7/Monday through Thursday)...

The extended forecast period will start out with highly amplified
upper level flow, supported by strong polar and subtropical jet
streams. An upper trough will be centered over nearly all of
Alaska, with an upstream ridge over the northwest Pacific and a
downstream ridge over western Canada. A deep low in the northwestern
Gulf Sunday night will head inland and rapidly weaken on Monday.
The track of the low inland is highly uncertain this far out, but
there is potential for wind and precipitation to spread inland
with the low. Moderate to heavy rain along the coast Sunday will
likely transition to mostly snow Sunday night into Monday morning
as cold air wraps around the low center. The remnant upper low
center and surrounding short-wave troughs will cause areas of
light precipitation to linger over southern AK through Tuesday,
while winds will lighten up significantly by late Monday.
Meanwhile, along the back side of the upper trough conditions
will be relatively quiet across the Bering Sea and Aleutians,
with just some snow showers early in the week.

As we continue to the middle of next week, attention will shift to
a rapidly deepening low tracking out of the northeast Pacific and
into the Gulf. There is some model spread in the placement of the
low in the Gulf, but good agreement in a vertically stacked low
staying over the Gulf. As a result, the primary impact will be
winds over the Gulf offshore and some of the nearshore coastal
waters. The bulk of precipitation with this storm looks to remain
offshore, perhaps bringing a period of light precipitation to
Kodiak Island the Gulf coast on Tuesday. Otherwise, the weather
looks mostly dry with seasonable temperatures for southern AK and
the eastern Bering Sea regions mid to late next week. As the upper
pattern continues to progress eastward, a new trough will bring
unsettled weather back to the Aleutians and western Bering Sea
Wednesday through Thursday, though features all look weak at this
point, with no significant impacts expected.

-SEB

&&

.AVIATION...

PANC...Snow continues through this morning along with MVFR to IFR
conditions. LIFR conditions are also possible within heavier snow
showers. Steady snow tapers off to scattered snow showers by mid-
morning today. MVFR conditions area still possible into the
afternoon hours with any snow showers that make it over the
mountains and into the terminal with VFR conditions between snow
showers. VFR conditions return for the remainder of the TAF late
tonight into Saturday morning as southeast flow strengthens.

Southerly to southwest winds today will eventually turn briefly
southeast late tonight before turning north by Saturday morning.
Gusty southeast winds bending into the terminal through Turnagain
Arm are possible late tonight into very early Saturday morning.
Strong down-inlet flow ensues Saturday morning at the end of the
TAF period as gusty Turnagain Arm winds bend southward with light
northerly winds across the terminal by then.

&&

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
1052 AM AKDT Fri Apr 11 2025

AKZ704-728-112130-
Portage-West Prince William Sound & Whittier-
Including the cities of Portage, Whittier, and Chenega
1052 AM AKDT Fri Apr 11 2025

...SNOW SHOWERS WILL CONTINUE TO BRING PERIODS OF SNOW TO WHITTIER
AND PORTAGE THROUGH EARLY AFTERNOON...

Scattered snow showers moving westward towards Turnagain Arm from
Prince William Sound will bring periods of brief, but heavy snowfall
from Portage through Whittier. Visibility may drop below 1 mile at
times with quick accumulating snowfall on untreated roadways.
Temperatures will rise above freezing by this afternoon, which will
limit additional accumulation on roadways. Showers will then
diminish by this evening.

Motorists are urged to slow down, turn on headlights, and use
caution when driving.

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
151 PM AKDT Fri Apr 11 2025

AKZ704-120100-
Portage-
Including the city of Portage
151 PM AKDT Fri Apr 11 2025

...SNOW SHOWERS WILL CONTINUE TO BRING PERIODS OF SNOW TO PORTAGE
THROUGH THIS AFTERNOON...

Scattered snow showers moving westward towards Turnagain Arm from
Prince William Sound will bring periods of brief, but heavy
snowfall to the Portage area. Visibility may drop below 1 mile at
times with quick accumulating snowfall on untreated roadways.
Temperatures will rise above freezing by late this afternoon,
which will limit additional accumulation on roadways. Showers will
then diminish late this evening.

Motorists are urged to slow down, turn on headlights, and use
caution when driving.

Preliminary Local Storm Report
National Weather Service Anchorage AK
321 PM AKDT Fri Apr 11 2025

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

0319 PM     Snow             Upper Potter Valley     61.06N 149.76W
04/11/2025  E5.0 Inch        Anchorage          AK   Trained Spotter

            24-hour snow accumulation. Estimated 5
            inches due to rapid daytime melting. Liquid
            water equivalent of 0.62 inches.

&&

CL