345
FXAK68 PAFC 230024
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
424 PM AKDT Thu May 22 2025

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

A surface wave of low pressure aligned with a rather robust 500
mb shortwave and associated dCVA is ejecting from the Aleutians
and phasing with a remnant area of low pressure in the Gulf of
Alaska. An occluded front continues to slowly shift southeastward
away from the northern Gulf coast, allowing rain to decrease in
coverage - although Kodiak Island will continue to see rain
showers through Friday morning.

Expect another round of southeasterly gap winds for Turnagain Arm
and the Knik and Copper River Valleys this afternoon and evening;
however, the magnitude of these winds will be less than what was
observed yesterday. Ageostrophic down-inlet flow will result from
relative high pressure in the interior and lower pressure to the
south. A few scattered showers will also be possible this
afternoon and evening, especially over higher terrain and along
the western foothills of the Talkeetna and Chugach Mountains. Some
of these showers may make it over the southern and western
portions of the Mat-Su Valleys.

Guidance is trending warmer for temperatures to approach or
surpass 60F Friday and Saturday, especially across the interior,
causing an increase in instability. Isolated thunderstorms are
possible across northern portions of the Copper River Basin Friday
afternoon and early evening as an easterly wave works westward
from Yukon, Canada. Likewise, Saturday also features increased
instability across the interior with the northeast Copper River
Basin looking the most unstable. While the best chance for
isolated thunderstorms will exist over the northeast Copper Basin
Saturday, western portions of the Susitna Valley could also have
enough instability present to generate a few lightning strikes
with any more intense showers that develop in the foothills of the
eastern facing slopes of the Alaska Range.

-TM/DAN/AM

&&


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

Weak, elongated low pressure is located along the central and
eastern Aleutians this afternoon, with a weak trough extending up
along the Kuskokwim Delta coast. Winds below gale force and light
rain result from the weak low along the Aleutians, while the
trough extending up to the Southwest coast has spread rainfall
across much of the Kuskokwim Delta and Nunivak Island. Elsewhere,
weak high pressure contributes to mostly dry conditions, though
some scattered showers are tracking west across portions of
Bristol Bay this afternoon. The Aleutian low drops south into the
North Pacific tonight, leading to some gusty northerly winds,
primarily through the eastern Aleutians and southern Alaska
Peninsula, as precipitation diminishes. The trough along the
Kuskokwim Delta coast lingers through the night, producing
continued scattered shower activity. Weak ridging builds in over
Southwest Alaska through the weekend, leading to increasing
temperatures and a general downtrend in precipitation. By
Saturday, high temperatures for interior portions of Bristol Bay
and the Lower Kuskokwim Delta reach into the mid 60s, and the
associated instability promotes scattered shower activity each
afternoon and evening.

Out west, a strong gale force low begins to move into the western
Bering Sea with the arrival of its front in the western Aleutians
tonight. Precipitable water values of 1-1.5 inches suggest that
rainfall could be moderate to heavy for the Aleutian Islands as
the front pushes east through the end of the week. The front
reaches the Pribilof Islands Friday night, though precipitation
amounts will be lower north of the Aleutian chain, and by
Saturday, as the front sweeps across the eastern Aleutians, the
front begins to weaken. Gale force winds will be limited to the
western Aleutians as the low center remains out over the far
western Bering until Sunday. Models suggest the low and front
progress east a bit slower than previously forecast, so steady
precipitation associated with the front may stall off the
Southwest coast on Sunday with only diurnal shower activity
bringing rain chances to the Southwest mainland. The approach of
the front and increased cloud cover, however, lead to cooler
temperatures on Sunday for Southwest Alaska, with many locations
that hit the threshold on Saturday failing to reach 60 degrees.

&&


.LONG TERM FORECAST (Days 4 through 7: Sunday through Wednesday)...

A broad upper level low stretches from Siberia across the Bering
before angling into the Gulf of Alaska. Several shortwaves help
the low centers slip through the pattern as the low becomes more
organized over the Eastern Bering and Western Mainland by the end
of the forecast period. The most persistent low anchors over the
Gulf of Alaska through midweek. Models favor the GFS through the
new week maintaining strengths and tracks of features.

Lingering showers are expected over the Southern half of Mainland
Alaska through Wednesday. A rain-wrapped low and front pushing
across the Central Aleutians and Bering brings moderate rain and
locally gusty winds into the Alaska Peninsula and Southwest Alaska
through Monday. The low sweeps into the Gulf of Alaska, spreading
the rain into Southcentral Alaska and North to the Alaska Range
until Wednesday. Snow is expected over higher elevations,
diminishing Tuesday. In the West, a well developed North Pacific
low and front does a drive-by over the Western and Central
Aleutians for Tuesday and Wednesday before curving back into the
North Pacific.

- Kutz

&&

.AVIATION...

PANC...VFR conditions are anticipated through the TAF period.
Southeasterly Turnagain Arm winds will increase early this
afternoon and persist through the evening hours. Gusts up to 25
knots are expected before diminishing overnight.

&&


$$