972
FXAK68 PAFC 191333
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
533 AM AKDT Wed Jun 19 2024

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

The upper level ridge continues to slide east with its axis over
the Alaska Panhandle this morning. This eastward progression of
the ridge will allow for the development of a more southerly flow
across the Gulf of Alaska that will advect a more stable airmass
over the southern half of Southcentral as well as drive a surface
front from the western gulf to the northern Gulf through Friday.

Weak upper-level waves will move through the southerly steering
flow between the exiting ridge and an advancing upper-level
trough. The first of these will move across the Copper River Basin
later today, allowing for the development of showers and isolated
thunderstorms across the northern and western periphery of the
basin. This trough should also allow for gap winds to develop
later this afternoon.

Along the coast, a marine stratus deck continues to hold over the
northern Gulf and immediate Prince William Sound coast. These
clouds should lift and become less expansive in coverage through
the day and into Thursday as influence from the aforementioned
ridge wanes.

By Thursday, the pattern will have shifted enough to have cleared
out the majority of very low clouds, but with southeast flow
aloft, more general cloudiness is expected over Southcentral for
the end of the week. The stable stratus marine layer clouds over
the northern Gulf of Alaska to be replaced by stratiform clouds
from the incoming trough, although enough instability may remain
in place along the Alaska Range for another round of showers and
isolated thunderstorms for Thursday afternoon. Southerly gap winds
will likely return for Thursday afternoon and evening as well.

All-in-all little change is expected for places like Kodiak, with
persistent easterly winds, clouds, and periods of light rain.

-TM/CL

&&


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


A North Pacific low will remain south of the area and reach the
Gulf by week`s end. Weak surface lows moving through the
Aleutians will bring continued southerly to southeasterly winds,
fog and scattered rain showers today there. A ridge will build in
the Central Aleutians tomorrow reaching the Eastern Aleutians
Friday morning with another low south of Adak as early as Friday
evening.

Scattered rain showers and a mostly cloudy sky is expected for
most of Southwest Alaska and the Alaska Peninsula today. The
North Pacific low working its way through the Pacific could cause
a weak wave of instability through the Alaska Range and Kuskokwim
Delta tomorrow afternoon. A few breaks in cloud cover could occur
tomorrow afternoon and evening resulting in a return of isolated
thunderstorms in this area. Though the thunderstorm chance is
greater (10%) for locations such as Sleetmute and Aniak compared
to Bethel (3%), some uncertainty exists for the amount of cloud
cover that will remain tomorrow afternoon and evening.

Friday afternoon and evening, a grater chance of scattered
thunderstorms, less cloud cover, increased CAPE and greater
instability, is likely in the Western Alaska Range and and
isolated thunderstorm in the Kuskokwim Delta. Elsewhere in the
Southwest, scattered rain showers are expected.



-DJ

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

Mainland Alaska remains under the influence of an upper level
ridge extending from Northwestern Canada through the forecast
period. Warmer than normal temperatures are expected over the
Southern half of the Mainland. On the surface, thermal troughs
support widespread convection. Arctic areas continue under a broad
low, with the Northwestern Bering low looping back into Siberia
for Tuesday. A very broad low stretches from Kamchatka across the
Aleutians and Bering into the Gulf of Alaska and Eastern North
Pacific. Model guidance continues in good confidence through most
of the period, but outliers develop into the new week. A series of
troughs slip along the Aleutians, spreading showers over the
Alaska Peninsula Southwest Alaska and Kodiak Island through
Tuesday. In the far West, a better organized front moves into the
Central Aleutians and Bering through Tuesday. A trough from the
Eastern North Pacific low brings showers to coastal locations from
the Canadian Border to Prince William Sound for the weekend.


-Kutz

&&

.AVIATION...

PANC...VRF conditions will prevail with westerly winds by late
morning becoming more southerly for late afternoon through
evening. Winds should remain 10 kts or less through the TAF
period; however, gusts to 20 kt are possible later this afternoon
and evening. Any gusts will diminish overnight when day-time
heating is lost.

&&


$$