099
FXAK68 PAFC 301325
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
525 AM AKDT Sun Jun 30 2024

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

Discussion:

The Bering low has ended its southward dive and will start to lift
northward along the south side of the far eastern Aleutians and
southern AKPEN today. The front looks to be bisecting Kodiak Island
this morning with the bulk of the rainfall having fallen late
yesterday and into the overnight hours resulting in about a quarter
inch of rain. As of this morning, only some light showers have moved
through and this on-again-off-again showers will be the trend for
the remainder of the day. Kodiak may see another round of more
widespread rainfall Monday as the Bering low edges closer and sends
another shortwave around its base.

Further north across the northern Gulf, a swath of rain is moving
eastwards towards the Prince William Sound and eastern Kenai coast.
This easterly wave will also help to advect a cooler, more moist
airmass into the Copper Basin today. While the Gulf coast coastal
mountains will see more uniform rainfall, the Copper Basin should
see more widely scattered showers develop and spread westward by
early afternoon. Models still favor an instability axis over the
Alaska Range and down towards the Talkeetna Mountains this
afternoon. As such, some isolated to scattered thunderstorms are
possible near the slopes of the Alaska Range, Wrangells, and
northern Susitna Valley with lesser chances down towards the
Talkeetna Mountains. May see a few showers clip the southern Kenai,
but as easterly cross-barrier flow establishes over the Kenai
Mountains and western Chugach, downsloping will keep most of the
western Kenai and Anchorage Bowl/Eagle River area dry. The Mat-Su
Valley also looks to stay mostly dry, though would be more
likely to see a few showers develop nearby.

A coastal ridge will also strengthen today with gusty gap flow winds
of 20-30 mph developing for the Turnagain Arm, Knik, and Copper
River Valley.

- PP

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA/ALEUTIANS
(Days 1 through 3: Sunday through Tuesday)...

A broad upper-level low continues to sit over the Bering as a
shortwave trough and subsequent front are moving towards the
eastern Aleutians and the Alaska Peninsula. Widespread
showers and gustier southeasterly winds are expected throughout
the day today and extending into tomorrow morning as the front
passes over the Southwest coast. On the backside of the upper
low, stronger northwesterly winds will impact the Pribilof Islands
and much of the central and eastern Aleutians through tomorrow
afternoon. In addition, extensive cloud cover over the Bering and
Southwest coast will also aid in keeping temperatures on the
cooler side in the near-term.

A secondary wave will begin to move over Southwest this afternoon,
starting over the Western Alaska Range and traversing
northwestward towards the Yukon Delta by Sunday night. The wave
will help produce widespread showers for much of the Middle
Kuskokwim Valley into this evening. An isolated thunderstorm is
possible over the area, but widespread cloud cover and cooler
temperatures may limit the extent of thunderstorm activity.

By this evening, a high amplitude ridge will build in over the
western Bering and slowly shift eastward over the next few days.
Widespread fog over is expected for areas under the ridge over the
Bering due to warmer temperatures aloft producing a steep
temperature inversion near the surface. The ridge will continue to
move eastward Monday and Tuesday, situating itself over the
central Aleutians and Pribilof Islands by the end of the forecast
period.

-BS

&&
.LONG TERM FORECAST (Days 4 through 7)...


Low pressure will move eastward through the Gulf of Alaska through
the end of next week. Its eastward trek will be inhibited
by the ridge in the Copper River Basin/Southcentral through this
time. Isolated to scattered thunderstorms are possible in the
Copper River Basin toward the end of the week, too.  Model
disparity of the low`s location and ridge`s westward progression
is high therefore, confidence in exact impacts and locations is
low. However, there remains high confidence that a ridge will
build into the Aleutians through the week.

-DJ

&&

.AVIATION...

PANC...VFR conditions expected on Sunday. The passage of a weak
trough through the Kenai Peninsula may result in temporary MVFR
ceilings and a low chance of some light, but brief, rain for the
rest of the morning. Turnagain Arm winds should return later this
afternoon and evening with southeasterly gusts up to 25 knots.

-BL

&&


$$