Gale Warning 165, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
437 PM AKST Wed Feb 7 2024

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

The overall pattern we've seen in place for the past couple days
remains in place, with multiple shortwave troughs lifting over the
top of a broad longwave ridge focused over the Northeast Pacific.
More specifically, a negatively tilted trough is now lifting into
the western Gulf and past Kodiak Island, helping to generate areas
of light rain and snow drifting into the southern Kenai Peninsula
and western Prince William Sound ahead of the approaching trough.
The rest of Southcentral is still situated under shortwave
ridging in place upstream from the trough over the western Gulf.
A few flurries are possible ahead of the trough axis as it lifts
through tonight towards the Cook Inlet and Mat-Su Valleys, but dry
conditions will generally persist for the remainder of
Southcentral through Thursday morning.

By Thursday afternoon, all attention shifts to a strong North
Pacific low already visible on satellite imagery well to the south
of the Aleutians. This low will approach the Alaska Peninsula late
on Thursday and push its occluding front north across the Gulf as
it does so. There is little change overall to the forecast
thinking for the progression of this system as it continues to
lift north over the course of the night on Thursday into Friday.
Strong east to southeast winds will spread north into the Kenai
and Chugach Mountains, Prince William Sound and along the
Turnagain Arm as the front lifts closer to the coast between
Thursday night and Friday. Moderate precipitation initially in the
form of snow will similarly spread into much of the same region
from south to north. However, warming low level temperatures will
result in a transition to rain near sea level, first along the
coast, then a bit farther inland along the Turnagain Arm and from
the Mat Valley south to the western Kenai Peninsula by Friday
afternoon. Very little precipitation will reach the ground to the
lee of the mountains (including the Mat Valley and Anchorage) through
Friday evening due to strong cross-barrier and downslope flow
ahead of the front. The opposite will be true on the other side of
the Kenai Peninsula, where upslope enhancement will lead to over a
foot of snowfall accumulation along the higher elevations of the
Seward Highway, namely through Turnagain Pass.

An warm, unsettled pattern will continue into the start of the
weekend through Saturday. As the front lifts north towards the
Susitna Valley and Copper Basin and as the parent low moves over
Southwest, flow will shift to a more southerly orientation. This
along with a southeast to northwest pressure gradient lingering in
place will allow winds blowing out of the Turnagain Arm to bend
north into Anchorage by early Saturday morning, with winds more
broadly switching to south to southeasterly elsewhere as well.
This may help much of the region hold on to surface temperatures
at or slightly above freezing in spite of slightly cooling
temperatures aloft. Multiple upper level waves will stream north
into Southcentral behind the frontal passage on Saturday, leading
to continued areas of snow possibly mixing with rain near sea
level at times through Saturday evening.

- AS

&&

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

A vertically stacked low is located over the northern Bering this
afternoon. Its associated surface front continues to decay across
Southwest Alaska and will promote some scattered snow and rain
showers through tonight. While this low weakens and tracks north
into Russia, a large North Pacific low tracks north to the Alaska
Peninsula on Thursday morning. Its front will lift north across
the rest of Southwest through Thursday as the low center tracks
along the Alaska Peninsula. The Pribilof Islands, eastern Bering
and Aleutians, and all of Southwest Alaska can expect to see the
majority of the active weather with this system. Easterly winds
are expected to be especially strong and gusty across the Greater
Bristol Bay area, eastern Bering, and Alaska Peninsula (including
the marine waters on its southern side). For inland Southwest,
most of the precipitation will be focused along the eastern-facing
slopes of the mountain ranges due to strong cross-barrier flow.
By Saturday, the low is expected to cross the Alaska Peninsula and
generally reach the Southwest coast/land. There are currently
some model discrepancies with the exact placement of the low
center for the weekend. Nonetheless, Southwest Alaska can
anticipate relatively active weather through at least Saturday.

For the rest of the Bering and Aleutians, persistent northerly
flow and cold air advection along the backside of both
aforementioned lows will promote continued widespread snow showers
through Saturday.

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

Large scale features persistent through the forecast period
include upper level ridging over northwestern Canada and the
eastern interior of Alaska, with an area of low pressure over the
Bering Sea and the western coast of Alaska.
Saturday morning a surface low over the Kuskokwim River Delta
continues on a northbound track and weakens. Sunday afternoon into
Monday morning a North Pacific low crosses the Alaska Peninsula
into the Bering Sea with storm force winds. Several shortwave
features pass over Kodiak and the western Gulf through Tuesday
morning.

&&

.AVIATION...

PANC...Expect increasing cloud decks above 10,000 feet this
afternoon and then lowering overnight and Thursday morning with
MVFR CIGS with light snow a possibility between 12z and 18z. CIGS
and VIS (if the drop) will slowly improve after 18z Thursday.
Light winds will persist through the duration of the TAF period.

-CC

&&