Gale Warning 305, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
511 PM AKDT Thu Apr 10 2025

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

This afternoon an upper level trough centered over the Bering
Strait, extends across Southwest Alaska, terminating in a
negatively tilted shortwave over the Gulf of Alaska. An associated
surface low in the Gulf has ushered several waves of
precipitation into Southcentral. With the exception of rain in
Cordova, and a rain/snow mix in Whittier, snow has fallen across
much of Southcentral for the much of the day. Precipitation is
expected to continue into Friday as another shortwave lifts
inland, shutting off by Friday afternoon for the Anchorage bowl
and northwestern Kenai Peninsula.

Conditions may be quieter Saturday morning while the upper level
low over the Bering Strait drops south through the Bering Sea, off
the western mainland coast. By Saturday afternoon the system will
have crossed the Alaska Peninsula into the North Pacific. It fuels
a surface low that will bring widespread gales and areas of storm
force wind to the northern Gulf. Precipitation will once again
blanket coastal Southcentral through the weekend, although warmer
surface temperatures may signal a rapid changeover from snow to
rain. Areas of lightning may be possible in the western Gulf
Sunday night into Monday due to cold, unstable air which moves in
behind the low, and relatively warm sea surface temperature in the
Gulf.

&&

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

Two lows bring impactful weather across much of the Bering Sea and
Southwest Alaska from Friday morning through Sunday afternoon.
Unfortunately, uncertainties with the track of these lows means
that while we do expect hazardous conditions, it's difficult to
pinpoint when and where the worst conditions will be until models
come into better agreement on the low tracks. For now, confidence
has been high enough for the issuance of a Winter Weather Advisory
for Nunivak Island and the Kuskokwim Delta coast from Friday
morning 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. With impactful weather forecast
but lower confidence in the details, please stay tuned as we
continue to update and refine the forecast.

Diving into the details... a weak surface low currently southwest
of Saint Matthew Island will rapidly strengthen as it moves
towards Nunivak Island by tomorrow 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.

As this compact surface low curves away from Nunivak Island and
towards the Pribilof Islands through Saturday, we're monitoring
the potential for blowing snow. This forecast has been difficult
because the forecast will be extremely sensitive to the low track,
and models have not shown great run-to-run consistency. Currently,
the low is forecast to track southwards just to the east of the
Pribilof Islands. This means that the Pribilof Islands will likely
see snow showers, but winds are right at the line of what we'd
like to see to forecast visibilities to one-half mile or less in
blowing snow. If the track shifts slightly westward, winds will be
weaker and blowing snow will not cause major visibility reductions.
If the track shifts slightly eastward, winds may be strong enough
to cause a blizzard. Given these uncertainties, we're planning to
wait at least one more model cycle before making a determination.

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.

-Chen

&&

.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 showers are expected to continue both at and around
the vicinity of terminal. IFR conditions will likely prevail
through the TAF period, though LIFR cigs and vis will be possible
late this evening through early morning Friday (2z through 10z)
at times during periods of more intense snowfall (with rates of
one inch or more per hour possible at times). Light northerly
winds will become more westerly this afternoon then become
variable by late evening.

&&