746
FXAK68 PAFC 292305
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
305 PM AKDT Mon Apr 29 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Monday
evening through Thursday)...

An upper-level ridge persists over Southcentral this evening with
generally clear and dry conditions. There are a couple of
exceptions to this. The first is an upper-level shortwave
dropping across the northern and western Copper River Basin. This
feature is producing some isolated showers, mainly from
Glennallen northwest along the Tok Cutoff. The other exception is
low stratus underneath the ridge lingering across Prince William
Sound. Another, more widespread area of stratus, is lifting north
across the Gulf of Alaska.

The ridge will begin to breakdown through Tuesday as the pattern
shifts. An upper-level trough will dig south over the AKPen which
will allow the upper level flow to turn southerly for Tuesday and
southeasterly for Wednesday. The southerly flow will advect more
moisture in the form of clouds and showers into Southcentral,
with the bulk of the precipitation across Kodiak, along the
immediate Southcentral coast, and across the south to
southwesterly facing foothills of the interior mountain ranges.
Most inland valley locations should remain dry due to downsloping
winds; however an isolated shower, especially Tuesday, is not out
of the question. The shift in the pattern will also bring a return
of southeasterly gap winds, with the strongest winds likely
Tuesday and Wednesday afternoon and evening across Turnagain Arm,
Knik River, and near the Copper River.

-TM

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today
through Thursday morning)...

The main upper level ridge over the Mainland is beginning to break
down and move east as multiple shortwave troughs move into the
region from the west and north. This ridging will likely lead to
more stratus and fog tomorrow morning before influence of the
approaching trough becomes the main weather feature. Winds will
increase along the Alaska Peninsula Tuesday night and encompass
most of Southwest Alaska Wednesday and Thursday. Precipitation
will mostly be confined to upslope areas along the northern
Bristol Bay coastline, but isolated to scattered showers are also
expected for other areas.

For the Bering, a gale force front is currently over Shemya and
will reach Adak and Atka around midnight. The front will slowly
weaken as the low occludes and stalls out west of Shemya. The main
forecast change is that the low is now expected to be broader and
farther north as it develops along the front and moves into the
Eastern Bering Wednesday and Thursday. This will bring light rain
and 15 to 30 kt winds to the Eastern Aleutians. On Thursday,
another low will take a similar track to the current system,
sending it`s front east along the Chain through Fri.

&&


.LONG TERM FORECAST (Days 4 through 7: Friday through Monday)...

A weak ridge wobbles between the Northern Interior and the Arctic
Coast and weakens by Monday. Elsewhere, a broad area of low
pressure stretches across the Aleutians and Bering into Mainland
Alaska through the forecast period. A series of surface low track
over or along the Aleutians and cross the Alaska Peninsula over
Kodiak Island into the Gulf of Alaska into next week. Ensemble
models demonstrate good confidence through the weekend, but
diverge into the new week. A well developed area of gusty winds
with gale force gusts push over the Western and Central Aleutians,
diminishing late Saturday, but linger along the Eastern Aleutians
and AKPEN for Sunday. Widespread precipitation accompanies the
low, with locally heavy amounts expected for the AKPEN and along
the Alaska Range and Eastern Kodiak Island Friday and Saturday.
Rainfall continues along the Eastern Kenai Peninsula over Prince
William Sound and along the Southcentral Coast through Sunday.

- Kutz

&&

.AVIATION...

PANC...VFR conditions and light winds will persist. High
confidence for Turnagain Arm winds to bend into Anchorage
tomorrow afternoon. There is moderate confidence regarding timing,
current consensus is the winds picking up around 4PM (00Z) tomorrow
afternoon with wind speeds 12 to 15 knots.

&&


$$