853
FXAK68 PAFC 240041
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
441 PM AKDT Tue Apr 23 2024

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

Quiet weather continues throughout much of Southcentral as a ridge
of high pressure aloft amplifies over the northern Gulf up into
central and eastern Alaska. This has resulted in much of
Southcentral finally seeing sunny to mostly sunny skies. The
exception would be the southern half of the Kenai and Kodiak Island
where increased cloud cover and showers have lingered as a weakening
trough moves southeastward. Showers will continue to wind down from
north to south this afternoon and evening; however, Kodiak Island
will likely see showers and foggy conditions through Wednesday
morning. The 12Z sounding showed decent conditions for diurnal
cumulus this afternoon, but they have been slow to form over the
bowl and Mat-Su Valley. If they do form, a drier boundary layer
should limit any light precipitation.

The ridge will strengthen overnight tonight before starting to tilt
back to the west as a large low over the Bering starts to drop
southward and a frontal boundary lifts north over the Gulf. The
ridge, sandwiched between the Bering low and a low over northern
Canada, will get squished between the lows by the end of the week.
The front associated with the Bering low will bring another round of
showers to the western Gulf, Kodiak Island, and the southern Kenai.
Vertical moisture profile is fairly limited so no heavy
precipitation is anticipated and more of a steady light rain.

- PP

&&


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

A vertically stacked low roughly 250 nm west of the Pribilof
Islands continues lift slowly northward this evening. Latest model
guidance is in good agreement with stalling the low`s northward
progress by midday on Wednesday. Thereafter, the low is forecast
drop southeastward, eventually crossing the Eastern Aleutians near
Unalaska sometime Friday morning in a weakened state. In the
short term, water vapor satellite imagery shows the tail-end of a
lengthy occluded front lifting into Cold Bay. The same front
extends from the AKPEN northward up into the Northeast Russia
coastline before wrapping cyclonically around the western Bering
back down to just north of the Central Aleutians and back
northward into the low`s center. Small craft to gale force winds
will remain within the low`s broad circulation, mainly west of a
line from the Pribilof Islands to Nikolski through tonight. Winds
should gradually diminish through the course of the day on
Wednesday.

Showery conditions will persist along the length of the occluded
front. Evening radar shows light showers extending from the Alaska
Peninsula into the Kuskokwim Delta. Much of this activity has
transitioned to rain for all but Toksook Bay. Shower activity will
also persist along the portion of the front extending through the
western Bering. Snow has changed from snow to rain for Adak while
a rain/snow mix is ongoing in Shemya. Into Wednesday and Thursday
areas of light precipitation will continue over much of Southwest
Alaska as the front moves further inland. A more focused area of
precipitation will span the Central and Eastern Aleutians as the
occluded low ventures southeastward into the North Pacific the
next couple of days.

&&


.LONG TERM FORECAST (Days 4 through 7: Sat through Tue)...

The low that is currently over the Bering Sea will have meandered
into the Gulf of Alaska by this weekend. The trough is tending to
linger there through the extended forecast period, slightly
nudging each day closer to the eastern Gulf. At the same time, a
ridge builds over the Bering Sea Sunday through Monday and begins
to toward Southwest Alaska as another low reaches the western
Aleutians by Monday night and western Bering for Tuesday.

Moderate to low confidence that the low in the Gulf will be south
enough to not have much QPF along the Gulf coast. This could mean
the potential for easterly waves to bring pop up showers though,
should skies be clear and enough moisture and instability for
those to develop. There is low confidence on this time interval,
especially over the Bering, where a front off the low will develop
and the timing as it progresses across the Bering early next
week.

rux

$$


.AVIATION...

PANC...VFR conditions and light winds will persist.

-CC

&&


$$