374
FXAK68 PAFC 280032
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
432 PM AKDT Sat Apr 27 2024

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

Currently, the pattern over Southern Alaska is defined by a
rapidly building upper-level ridge over the area, with a low
pressure system in the Southwestern Gulf of Alaska. The low is
weakening and shifting quickly out of the area, as well as it`s
associated frontal boundary along the northern edge of it,
bringing showers into Kodiak Island this afternoon. Influence from
this low and front will cease overnight tonight as the ridge
grows and shifts more so over Southcentral Alaska. This will
encourage a predominantly clear pattern over our area through the
remainder of the weekend, and even into middle of the next
workweek. While the ridge is still building this weekend, cooler
air remains aloft, and along with the clear skies, ample surface
heating would be conducive to localized convective showers around
Southcentral. However, given the strength of the ridge, any
showers produced this way would likely be isolated and short-
lived. Additionally, given the surface heating, a return of the
Summer seabreeze is expected this weekend, predominantly Sunday,
in marine communities such as Seward, Valdez, and Whittier.

One area that may be more favorable for the aforementioned shower
activity, would be the Copper River Basin for late this weekend
into early next week. This area appears to have a bump up in
instability during this time due to a weak upper-level trough
riding up along the ridge. Showers produced by this would likely
originate over elevated terrain near the Wrangells and further
west into the Copper River Basin. There is still some uncertainty
how far west these showers may spawn. High-res guidance suggests
some showers may develop over the Talkeetnas down to Hatcher Pass.
Given that much of these elevated areas have lost significant
portions of snowpack, this provides an elevated source of heating
that may kick-start some showers. The likelihood of these showers
transitioning to thunderstorms is very low. Vertical motion and
lift from these systems would likely not be strong enough to
produce such an organized system. By Monday, will also see a
general increase in cloudiness across Southcentral as the weak
upper level ridge begins to breaks down.

-CL

&&


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

A ridge of high pressure remains over much of the Mainland as
evident by clear skies and warm temperatures over much of the
area. Over the Bering, multiple shortwaves, troughing and cooler
air is leading to some cloud cover and precipitation. A system
currently south of the Alaska Peninsula will continue to shift
south, leading to clearing or at least drier conditions for the
area. The other system of note is a weak low and upper level
shortwave south of the western Aleutians this afternoon. This
system will continue to graze the Chain as it moves east through
Sunday night. Nothing more than light rain and breezy conditions
are expected. For interior areas, a few more days of sun and warm
temperatures are expected before clouds return.

By Monday, a moderately strong system will move into the western
Bering, bringing southerly gales and rain to the western Aleutians
Monday. The front will slowly weaken as it moves east Tuesday,
bringing more widespread, but light rain to the eastern Aleutians
and Alaska Peninsula.

&&


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

A broad area of upper level low pressure extends across the
Bering through the forecast period. Several closed centers with
their associated fronts rotate over or to the South along the
Aleutians into the Gulf of Alaska and weaken slowly. A separate
low center travels across the Northern Mainland into the Arctic
through Friday, with a trough stretching back to the Bering low. A
weak ridge extending over the Mainland from Canada takes over
Interior weather through Thursday, then weakens through Saturday
as the Bering low slips into Western Alaska. Features overall are
best forecast using ensemble means, with fair confidence allowing
for some minor variations with the embedded systems moving
through.

The weather forecast opens with a Central Aleutian low and front,
pushing over the AKPEN, Kodiak Island and across the Gulf by
Saturday. Areas of locally heavy rains and some gusty winds spread
Eastward across Kodiak Island late Thursday into Friday and
across Southcentral Alaska through the week. A second and more
potent low and front moving out of Kamchatka enters the Western
Aleutians and Bering late Wednesday. Gusty winds and rain expand
over the region as the low moves to the Eastern Aleutians and
frontal weather spreads over much of the Bering and Western Alaska
by Saturday. Considerable cloudiness and rainfall will continue
over the entire Aleutian chain for the weekend.


-Kutz

$$



.AVIATION...

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

&&


$$