523
FXAK68 PAFC 230038
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
438 PM AKDT Sat Jun 22 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: This
afternoon through Tuesday)...

It has been a very warm day across Southcentral with northerly
winds bringing in dry air and warming most places into the 70s,
including Kodiak and Anchorage. Seward joined the 70 degree club
before the sea breeze kicked in and cooled them off. Temperatures
pushed the 80 degree mark in the Susitna Valley and some northern
sections of the Copper River Basin. The northern Susitna Valley
and northern Copper River Basin have been hot, dry, and windy
enough for a Red Flag Warning through 10 PM tonight which denotes
the potential for extreme fire behavior.
While there has been limited convection as of early this
afternoon, cumulus fields are seen on satellite building over the
Talkeetna Mountains and Alaska Range. This area should build
farther southward this evening with isolated thunderstorms
possible over mountains this afternoon and evening. Sunday looks
like a better day for thunderstorm potential as the airmass over
Southcentral will be more unstable. One item of note is that the
GFS, Canadian, and HRRR models are all indicating for some 500 mb
vorticity advection over the Kenai, Chugach, and southern
Talkeetna Mountains Sunday evening. Should this occur, there might
be more organized convection for these areas which would hold
together off the mountains allowing the thunderstorms to move over
the Mat-Su Valleys, Anchorage and the western Kenai Peninsula.
This is not a terribly strong signal, but in an unstable
environment it could cause increased thunderstorm development.

Monday and Tuesday will see continued afternoon and evening
showers and thunderstorms, especially over mountainous areas.

&&


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

High clouds have persisted over much of the Middle Kuskokwim
Valley and Western Alaska Range on Saturday within the presence of
an upper trough. However, this has not prevented the development
of weak instability over the region. A few showers and
thunderstorms have already materialized over the Western Alaska
Range and to the north and northeast of Lime Village. Additional
wet thunderstorms will be possible across both the Middle
Kuskokwim Valley and Western Alaska Range through the evening
hours, as they meander generally southward. Temperatures on
Saturday have largely underperformed with high temperatures
struggling to get out of the upper 60s.

Sunday will likely be another day of cooler temperatures across
Southwest Alaska with areas of continued cloud cover. The trough
currently over the region should begin to meander southward,
allowing more breaks in cloud cover and another round of late
afternoon/evening showers and thunderstorms across the Middle
Kuskokwim Valley and Western Alaska Range.

Looking west, an occluded low skirting the Eastern Aleutians this
evening is forecast to drop southward into the North Pacific
through Sunday afternoon. Models are slowly coming into better
agreement with the arrival of the next upper low into the Western
Aleutians on Monday afternoon. This low will deepen into the 980
mb range while tracking just north of the Central Aleutians into
Tuesday. Expect widespread showers across the Western and Central
Aleutians on Monday with small craft easterly winds overspreading
the region over the latter half of the day.

BL

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

The long term consists of a high amplitude ridge over the AlCan
border and a high amplitude trough over the Bering. This will lead
to fairly bimodal weather between the Bering/Southwest and
Southcentral. In general, the Bering and Southwest will be wetter
and cooler than what has been observed recently as a series of
shortwaves move from the Bering and into Southwest Alaska and the
west coast. Southcentral will likely be cloudier in this pattern,
though influence from the ridge will keep temperatures above
average with possibilities of breezy conditions and thunderstorms.
The main uncertainty in the forecast for Southcentral will be how
far east the shortwaves are able to make it, and therefor the
extent of convection and rain.

-Jones

&&

.AVIATION...

PANC...VFR will persist through the TAF period. Winds will
increase out of the south through the evening and then abate again
overnight. Most shower and thunderstorm activity will remain out
of Anchorage today, but cannot completely rule out a shower or
two making it near Anchorage. Probability of daytime showers or
thunderstorms is a slight bit higher on Sunday, as easterly flow
aloft will assist in the westward movement of any convection that
develops across the Chugach front range.

&&


$$