263
FXAK68 PAFC 201232
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
432 AM AKDT Sun Apr 20 2025

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

Cloud cover and precipitation will spread slowly from southwest
to northeast over the next 24 to 36 hours as an upper level trough
currently over the tip of the Alaska Peninsula pushes into the
shortwave ridge currently over Southcentral. The Kenai Peninsula
and Kodiak Island will be the first to receive some light rain
today as a leading shortwave moves over these areas. Otherwise,
the remainder of Southcentral will have some southeasterly gap
winds and increasing clouds. By Monday morning a closed upper low
will move over the Kenai Peninsula, producing lift for widespread,
very light precipitation throughout Southcentral. Temperatures
aloft remain fairly cool, which will support snow in the Copper
River and northern Susitna Valleys and a mix of rain and snow at
sea level elsewhere Monday morning with temperatures in the mid-
to-low 30s.

By Monday afternoon the upper trough will shear apart, leading to
a more showery regime. The focus will then shift to a broad upper
low and its evolution as it moves over the Alaska
Peninsula/Bristol Bay Monday night into Tuesday. The majority of
the forecast guidance has this low splitting apart, with the
southern piece of energy moving into the Gulf or over Kodiak
Island Wednesday morning. This will reintroduce southeasterly flow
aloft, coastal precipitation, and gale force winds over most of
the coastal marine zones. The north/south position of this low
will determine the intensity of the wind and rain in the Sound,
Kodiak Island, and northern Gulf.

-CJ

&&


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

The relatively quiet weather across the Southwest mainland is
coming to an end with the approach of a weak low in the Bering.
This low will knock the ridge that is currently over the Southwest
mainland out of the area, pushing it eastward. The low`s front
will shortly bring about increased precipitation chances and
warmer air. Due to the warmer temperatures, most precipitation
will be in the form of rain. However, the Kuskokwim Delta coast
and the western capes of Bristol Bay could see some snowfall
before transitioning to rain when temperatures warm above freezing
Sunday afternoon. Snowfall totals are uncertain and will highly
depend on how long temperatures remain at or below freezing. Due
to the weak nature of the low, wind speeds will remain quite low,
even when the front pushes onshore. As for the Bering, they will
continue to see areas of low stratus and scattered rain through
Monday.

On the heels of the first low comes a second low. This low is
also on the weaker side, but will increase wind speeds and
precipitation chances a little bit in the western Aleutians before
moving east. This low will absorb the first low and will grow
into one big, weak low by Monday afternoon. The effects of this
merger are wider swaths of precipitation and weaker than small
craft winds that stretch from the western Aleutians to the
mainland. The back end of this low will have winds turn northerly,
so cooler air gradually advects into the Bering through Tuesday,
particularly at higher levels.

By Wednesday, the big, weak low will have moved off into the Gulf
of Alaska and precipitation chances and wind speeds will diminish
as a ridge builds in. Winds will remain northerly, allowing for
cooler temperatures aloft. Surface temperatures, however, will be
warmer than before during the day as skies become more clear. By
Wednesday afternoon, another low will push into the western
Aleutians, bringing stronger winds and more precipitation than the
previous lows. Confidence is not yet high on the potential of
this low.

-JAR

&&
.LONG TERM FORECAST (Days 4 through 7/Wednesday through Saturday)...

The Alaska upper level weather map opens with an energetic
pattern with several significant shortwaves passing across the
region. A closed low South of Kodiak Island drifts along the
Southern Gulf before exiting Southeastward for Friday. A moderate
amplitude but narrow ridge over the Central Aleutians and Bering
weakens and flattens as it moves into the Eastern North Pacific
through Saturday. A second low enters the Bering from the Russian
Far East, centers over the Central Aleutians and expands all the
way across Mainland Alaska into the Canadian Provinces in more
zonal flow by the weekend. A loose ECMWF / GFS / Canadian cluster
renders into an ensemble blend by Saturday, but supporting surface
instability throughout the period.

A moderate strength surface low South of Kodiak Island spreads a
shield of locally moderate rain from the Alaska Peninsula over
Kodiak Island and along the Southcentral Coast to the Canadian
Border through late Thursday before diminishing. Areas of snow are
expected inland, mostly over higher elevations. To the West, a
well developed North Pacific low and front pushes over the Western
Aleutians and Bering Wednesday. The system continues to spread
locally moderate rain over the Central Aleutians and Bering
Thursday before diminishing across the Eastern Bering and Alaska
Peninsula for Friday. Interior Mainland areas should remain under
quiet weather conditions.

- Kutz

&&

.AVIATION...

PANC...VFR conditions and light winds will persist through Sunday
morning. Southeasterly Turnagain Arm winds gusting up to 25-30
knots are likely to affect the terminal beginning Sunday
afternoon. At the same time, ceilings may begin to drop below 5000
ft, but are most likely to remain VFR. There will be a chance of
light rain Sunday night after midnight through late Monday
morning and gusty winds may become more intermittent. With heavier
periods of rainfall, there is some potential for ceilings to drop
to MVFR. By Monday afternoon, ceilings improve back above 5000 ft,
rain clears out, and Turnagain Arm winds move back into the
terminal more persistently.

&&


$$