094
FXAK68 PAFC 300041
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
441 PM AKDT Sat Jun 29 2024

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

A Bering Sea low is continuing to sink south with its front
pushing northward into the western Gulf and nearing Kodiak Island
by late tonight. Steady rainfall has already started. Models
consensus on total rainfall amounts differ quite a bit for Kodiak,
but on the low end Kodiak City could see a quarter inch through
Monday and up to an inch on the higher end. The expected total is
around three quarter inch or so through Sunday night. Kodiak could
start to see decreasing chances for rain Monday morning, though
the synoptic pattern will not change very much and chances for
showers will remain possible through the short term forecast for
Kodiak Island.

The upper ridge will start to build back into the central
interior of Alaska with ridge axis positioning itself along to
just north of the eastern Alaska Range by Sunday. Isolated
thunderstorms are possible along the slopes of the Alaska Range
and Wrangell Mountains Sunday, though models are hinting that a
low end instability axis might extend over towards the Talkeetna
Mountains and northern Susitna Valley Sunday afternoon.

With the Bering low and front to the south and west, and the
upper ridge building back west to the north...Southcentral will
see increasing easterly flow resulting in a more unsettled pattern
for the latter half of the weekend into early next week. Rain
showers will become more widespread overnight tonight into Sunday
morning for the northern Gulf as remnant lows in the eastern Gulf
become easterly waves. More widely scattered showers expected for
the Copper River Basin and northern Susitna Valley. The eastern
Kenai, Prince William Sound, and northern Gulf coast will see the
bulk of precipitation as the western Kenai, Anchorage Bowl, and
Mat-Su Valley will likely see downsloping set-up with lesser
chances for any showers. Chances for showers will gradually
decrease early Monday along the coast, but remain isolated to
scattered closer to terrain of the Susitna Valley and Copper River
Basin through Tuesday. Lastly, increasing pressure gradients
along the Gulf coast will result in gusty gap winds developing for
the Turnagain Arm and Copper Basin. The pressure gradient, and
therefore winds, could weaken Tuesday.

- PP / rux

&&


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

A broad, longwave trough continues to sit over the Bering,
anchored by a vertically stacked low centered north of Atka.
Downstream of this feature, a shortwave trough and attendant
surface front are moving from the eastern Aleutians to the Alaska
Peninsula this evening. The result is continued widespread shower
activity stretching from coastal Bristol Bay north to the
Kuskokwim Delta. Southeasterly winds ahead of the front are gusty
along the Southwest coast this afternoon. Extensive cloud cover
over Southwest Alaska is also helping to keep temperatures on the
cooler side.

The aforementioned low will slowly slide southeast through
Sunday, bringing persistent showers to the eastern half of the
Aleutian Chain, as well as coastal Southwest Alaska. In the wake
of the low, gusty northwesterly winds are expected from west of
the Pribilofs south across the central Aleutians due, in part, to
increasing instability as colder air works in aloft.

A secondary upper-level wave will move over interior Southwest
Sunday. This feature will produce widespread showers for the
Middle Kuskokwim Valley. An isolated thunderstorm is also
possible; however, convective parameters are marginal at best.

By Sunday evening, a large amplitude ridge of high pressure will
build over the western Bering and push eastward through at least
the end of the forecast period. Widespread fog is likely
underneath the ridge as temperatures at the surface remain quite
cool but temperatures aloft (~850mb) warm to 10C or warmer. The
ridge axis, as well as the fog, moves east from the western Being
to the central Bering and Pribilof Islands for Monday and Tuesday.

-TM

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


Low pressure will move eastward through the Gulf of Alaska through
the end of next week. Its eastward trek will be inhibited
by the ridge in the Copper River Basin/Southcentral through this
time. Isolated to scattered thunderstorms are possible in the
Copper River Basin toward the end of the week, too.  Model
disparity of the low`s location and ridge`s westward progression
is high therefore, confidence in exact impacts and locations is
low. However, there remains high confidence that a ridge will
build into the Aleutians through the week.

-DJ

&&

.AVIATION...

PANC...VFR conditions with light wind will persist through
Saturday afternoon. Slightly strong southeast winds out of the
Turnagain Arm may brush ANC this evening, but confidence remains
low. General light and southerly winds are expected to prevail
this evening. Confidence is significantly higher that strong,
gusty southeast winds will increase in strength Sunday afternoon
and continue through through into early Sunday night.

&&
$$