605
FXAK68 PAFC 271336
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
536 AM AKDT Thu Jun 27 2024

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

Discussion:

A large occluded low continues to spin over the Bering this morning
with frontal boundary slowly pushing across the AKPen and western
Gulf towards Kodiak Island. The southern portion of the front will
then stall near Kodiak and gradually wash out over the next several
days as the main upper forcing lifts across western Alaska. With the
stalled front nearby, Kodiak will see off-and-on light rain showers
and foggy conditions through the day today. Surface ridge over the
northern Gulf will elongate southeastward in response to the
approaching front allowing stratus to linger over the Prince William
Sound and coastal areas.

The Kenai Peninsula and southwestern portions of Southcentral will
see increasing cloud cover moving in from the south; however, the
northern edge of the cloud cover may erode some later today. The
upper ridge has shifted north and east with axis extending from
northeast Alaska down into northern British Columbia. This will
shift the best thunderstorm chances for Southcentral eastwards into
the Copper River Basin, though there may still be a few storms near
the Talkeetna Mountains this afternoon. Lack of any forcing feature
will result in the bulk of today`s convection to be diurnally
driven, and storms will quickly dissipate this evening as prime
daytime heating ceases. Friday will favor a similar set-up today,
but with ridge shifting even further east, best convection chances
will also shift to the east.

With surface ridge being squashed up against the northern Gulf
coast, the pressure gradient will steepen over the Chugach Mountains
allowing for some southerly gap winds to develop in the southern end
of the Copper Basin. Temperatures look to reach into the upper 70s
to near 80 if cloud cover remains fairly minimal, and with dewpoint
dropping into the lower to mid 40s...could see relative humidity
drop into the 25 to 35 percent range. The question will be how much
(if any) cloud cover spills into the southern end of the basin and
if the more moist southerly winds may help to modify the dewpoints
this afternoon.

- PP

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA/ALEUTIANS
(Days 1 through 3: Today through Saturday night)...

The forecast remains on track for the Southwest coast to remain
cooler, unsettled, and showery the next few days with warmer and
relatively drier conditions the interior locations. The interior,
especially along the Western Alaska Range, eastern portions of the
Lower Kuskokwim Valley, and along the Aleutian Range in interior
Bristol Bay have the chance at afternoon showers the next few
days. The best chance will be Friday afternoon. However, the
chances for lightning strikes is very low at this time as the air
should be more stable than it has been the previous few afternoons
across interior Southwest. With that, the frontal system that
lashed the Southwestern coast has weakened and continues to weaken
as it pushes further inland this morning. With the weakening
trend, winds and water levels have come down along the Northern
Kuskokwim Bay coast and the High Surf Advisory has been allowed to
expire. However, there could be another, albeit smaller, secondary
rise in water levels this afternoon aided by another push of
southeasterly flow from the central Bering low. Winds are also not
expected to be as strong as what was witnessed yesterday.

Meanwhile, the central Bering Sea low will continue pushing waves
of moisture into coastal Southwest through Friday while will help
to keep rain chances going. This low will eventually pivot back
towards the northwest Bering by Saturday. A shortwave is then
expected to lift east-northeastward through Saturday and
eventually make it to the southwest Gulf of Alaska Saturday night
and Sunday. This will aid in focusing precipitation along the
Aleutian Chain and southern Alaska Peninsula for Friday through
Saturday evening before it becomes more scattered and showery
Sunday morning. By that time, the low pressure in the northwest
Bering turns back and loops southward back into the south-central
Bering by saturday afternoon. The track of this low will aid in
focusing precipitation along the Pribilof Islands Friday night and
most of Saturday. This low will continue to spin in the vicinity
of the Pribilofs into Sunday as a frontal system moves over the
western Aleutians by then.

&&

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

A ridge will begin weaken over the Southcentral and Copper River
Basin Sunday. Isolated rain showers or thunderstorms are possible
though into the beginning of next week. An area of low pressure
will form in the Bering Sea and move into the Gulf of Alaska
Tuesday morning bringing precipitation and gusty winds to Bristol
Bay and the Alaskan Peninsula by mid week.

-DJ/DD

&&

.AVIATION...

PANC...VFR conditions are expected to persist through the TAF
period, with light southwesterly up-inlet flow prevailing into
Friday. Building high pressure over the area will also result in
decreased precipitation chances over the terminal.

&&


$$