335
FXAK68 PAFC 241328
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
528 AM AKDT Fri May 24 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:
Tonight through Sunday Night)...

Cool, cloudy weather with increasing rain chances will characterize
the end of the work week for southcentral Alaska. GOES water vapor
imagery shows an upper-level low currently off the SW coast of
Alaska with a leading shortwave trough ejecting towards the Kenai
Peninsula. Radar imagery shows light and scattered shower activity
has already begun to move into the central and southern Kenai
Peninsula.

Showery activity is expected to advance a bit farther north today
towards Anchorage and the Mat-Su Valley, but likely be much more
spotty in nature. High-resolution models suggest the bulk of todays
precipitation will remain from about Soldotna-Kenai southward, as
well as communities adjacent to the Gulf of Alaska and Prince
William Sound.

As a triple point low develops along the front in the Gulf today, a
weak coastal ridge builds. This will drive southerly winds through
the typical gaps, including Turnagain Arm, the Knik River Valley,
and the Copper River Valley. The low shifts into the central Gulf
tonight, allowing the coastal ridge to relax and gaps winds to
diminish. Cooler air aloft accompanies the low, which will drop snow
levels to around 2500 ft through much of the coastal mountains. The
main impact will be potential for light snow through Thompson Pass
tonight.

The low`s front lingers along the coast, keeping these areas wet
through Saturday. Further inland, a shift to northerly flow as
the low tracks into the Gulf will lead to some initial drying and
breaks in the clouds to start the weekend. One exception is an
upper-level easterly wave which tracks across the Copper Basin on
Saturday, bringing further rainfall.

On Sunday, confidence is increasing that an upper-level low will
move from the North Slope southwestward to western Alaska. This
will place portions of southcentral Alaska, such as the Susitna
Valley south through the Cook Inlet, between southwest flow of
this system and east/northeast flow from the departing low. The
low/mid-level convergent flow, a deformation zone with a col
centered near Anchorage, will result in additional rainfall for
these areas. The NAM and its derivatives are the most bullish on
the precipitation, suggesting that it develops by late Saturday
evening. Meanwhile, most other guidance suggests precip will hold
off until Sunday. Either way, expect continued cool and cloudy
weather with the occasional shower.

-Brown/Quesada

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA AND THE
ALEUTIANS (Days 1 through 3)...

A vertically stacked low sits roughly 80 nautical miles north of
the Pribilof Islands this morning. Downstream of the low a
shortwave trough is lifting through the Kuskokwim Delta with
scattered showers. Additional shower activity is noted over
Greater Bristol Bay with a second shortwave shifting into Cook
Inlet. Westerly winds continue to gust to gale force along the
Eastern Aleutians, both on the Bering side and the Pacific side.
Gusty conditions will linger from Nikolski to Unalaska to Cold Bay
through Saturday morning with winds ranging from 25 to 35 mph.

The weather story remains the same for Southwest Alaska with
below normal temperatures and showery conditions expected to
persist through Saturday. The low tracks into the Gulf of Alaska
Saturday morning and associated rain over Southwest Alaska is
forecast to taper off throughout the second half of the day as a
result. In the low`s place a tightened pressure gradient over the
eastern Bering will promote northerly winds over the Bering and
into the Eastern Aleutians and Alaska Peninsula. Sunday will see
winds trend downward across Southwest Alaska and any remaining
rain comes to an end. The next weather system begins to take shape
as a Kamchatka low brings a front into the Western and Central
Aleutians late Sunday.

-BL

&&

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

The Alaska Weather Map is under a very broad area of upper level
lows, with three separated centers. The first is a weakening
center in the Southern Gulf of Alaska/Northeast Pacific that is
drifting Eastward. The second is a somewhat energetic center
meandering around the Bering Strait. The weakest of the three is a
center in the Western Aleutians and Bering. The main focus is
along the Southern portions of the state with additional energy
that arrives via the North Pacific through the forecast period.
The Northern low center contributes to weather producers over
Western Alaska. Model confidence is good with a deterministic
blend changing over to a one-half ensemble blend by midweek. The
end result is an elongated areas of low pressure extending across
the Bering into the Gulf for Thursday.

Overall looking at a good mix of sunny breaks and wetter weather.
Periods of rain spread across Southcentral Alaska to just North
of the Alaska Range through Thursday. A well developed front
brings locally heavy rain over the Aleutians and Bering, spreading
into Southwest Alaska late Wednesday. A second well developed low
and front bring another round of locally heavy rain into the
Western Aleutians and Bering late Wednesday into Thursday.

-Kutz

&&

.AVIATION...

PANC...VFR conditions will persist throughout much of the TAF
period. A frontal system will move up into Southcentral later this
afternoon, bringing some potential for periods of light rain to
reach the terminal along with possible ceiling reduction below
5000 ft. Turnagain Arm winds are likely to develop and bend into
Anchorage late this afternoon and evening, with southeast gusts up
to 25 kts possible until winds diminish later tonight.

&&


$$