126
FXAK68 PAFC 160105
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
505 PM AKDT Sat Jun 15 2024

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

Only small changes to the forecast as we move into Sunday. High
pressure over western Alaska will begin to retrograde west and
northwest as an area of high pressure over interior Alaska drops
southward over the Alaska Range and Copper River Basin. A weak
upper low over the northern Gulf will pivot west and southwest
through Sunday night, becoming an open wave trough over Kodiak
Island by Monday morning. Warm temperatures and the chance for
convection remain the biggest concerns the next few days across
Southcentral. Saturday saw widespread upper 70s temperatures
across Southcentral with lower 80s temperatures observed across
the Susitna Valley and inland of Western Kenai Peninsula. This
resulted in RH values down to 25% or lower for the Susitna Valley
and also across the Copper River Basin. A lack of meaningful wind
has precluded hot-dry-windy conditions, but showers and isolated
thunderstorms will remain possible through the evening hours. A
strong, but not severe, storm was noted near Cooper Landing
earlier today with numerous lightning strikes noted on satellite.

For Sunday, high pressure shifting over the Copper River Basin
will see subsidence (sinking motion) and a stronger capping
inversion (think stable layer of warmer air aloft). This will
spell a break from precipitation over the Copper River Basin. The
threat for convection will thus be confined to along and west of
the Talkeetnas where high pressure is weaker, as well as further
south into the Western Kenai Peninsula. Temperatures will be
relatively cooler across the Mat-Su and Western Kenai Peninsula,
with fewer locations reaching 80 degrees. Further east and beneath
high pressure, the Copper River Basin is more likely to see a
greater number of locations warm into the upper 70s, a small
change from Sunday.

Monday continues the cooling trend as high pressure breaks down
over the Copper River Basin and a trough lifts from the western
Gulf into the Susitna Valley. Isolated to scattered showers and
thunderstorms will again be possible during the afternoon and
evening hours.

&&


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

An upper ridge remains over interior Alaska with weak upper level
shortwaves supporting thunderstorm activity across Southwest
Alaska, particularly along the western Alaska Range, through late
this evening. Convective activity is expected again across these
areas Sunday afternoon and evening. By Monday, a relatively
stronger easterly shortwave moves through supporting the potential
for more widespread thunderstorms extending from the western
Alaska Range through the Kuskokwim Delta.

A front and associated upper level low sitting over the Central
Aleutians will continue to bring rounds of rain showers and small
craft winds to the Western/Central Aleutians through the rest of
this weekend. Rain chances also return to the eastern Aleutians
Monday as a weak surface low forms south of the Aleutian Chain.

-ME

&&


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

A broad upper-level low extending along and south of the Aleutian
Islands and Alaska Peninsula on Wednesday shifts eastward through
the end of the week. Rainy conditions associated with a weak front
shift from the Alaska Peninsula, Kodiak Island, and Bristol Bay
into the Gulf of Alaska for Thursday. A series of shortwave
troughs embedded in the broad upper low lift into southern
mainland Alaska and then rotate westward on Thursday and Friday,
bringing a slight cooldown and wetter conditions. Increased lift
afforded by these shortwaves will lead to areas of more
widespread, steadier rainfall across portions of Southcentral and
Southwest Alaska. For Friday, a North Pacific low passes south of
the Gulf of Alaska, approaching Southeast Alaska/Haida Gwaii by
Saturday. The low pressure draws theta-e ridging southward from
Interior Alaska, allowing a return to warmer weather and
thunderstorm potential for the southern mainland next weekend.

Out west, surface high pressure over the Bering Sea will likely
support widespread fog and low stratus across the western and
central Bering on Wednesday and Thursday. A North Pacific low,
potentially gale-force, begins to push into the western/central
Aleutians for Friday, scouring out some of the fog, but bringing
windier, wetter conditions. Heading into the weekend, the low
progresses north and east, spreading rain and gusty southeasterly
winds potentially as far as the Alaska Peninsula.

Quesada

&&

.AVIATION...

PANC...VFR conditions and light winds will generally prevail
throughout the TAF period. Showers are expected to develop and
move off the mountains through the afternoon and evening hours
today. Can`t rule out a thunderstorm as well, but probability
remains too low for TAF inclusion at this point. Showers will
again develop on Sunday with coverage similar or a bit less than
that of today.

&&


$$