464
FXAK68 PAFC 200043
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
443 PM AKDT Fri Jul 19 2024

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

The warmer and drier weather has arrived today and is expected to
persist through the weekend. The only caveat is that mesoscale
easterly waves will move near or over Southcentral this weekend.
While most areas will stay dry, there is a chance of isolated
thunderstorms over the Copper River Basin and Mat-Su Valleys
Saturday with potentially a little more coverage on Sunday with
warmer temperatures and more instability expected. Depending
exactly where exactly the mesoscale waves track, the Chugach and
Kenai Mountains, including potentially the Anchorage Hillside, and
along either side of the Kenai Mountains, have a chance to see an
isolated storm for Sunday afternoon and into the evening.
However, confidence is low and there is uncertainty with the
tracks of the mesoscale waves. The warmest locations this weekend
will continue to be the Copper River Basin and Susitna Valley were
temperatures could touch 80 degrees. The warmer and drier weather
comes to an end on Monday as a more powerful easterly wave from
Yukon, Canada moves westward over the Copper River Basin
initially, and then the rest of mainland Southcentral through the
day.

&&


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

The axis of a high pressure ridge is spans from the eastern
Aleutians to the Southwest coast this afternoon. An occluded low
is centered over the western Aleutians with its triple point
located near Nikolski. A long fetch of subtropical moisture is
expected to spread across the Aleutians and into the Bering Sea
over the next few days.

Precipitation is moving through the central Aleutians and Bering
Sea, but later this evening, precipitation will lift into the
northern Bering and spread east to the Pribilofs and the eastern
Aleutians. Precipitation should remain steady and light, with
smaller moderate to heavy bands between Unalaska to the Pribilofs
by Saturday morning. The low will slowly linger in the Southern
Bering Sea while its front will slow down considerably as it
continues across the eastern Bering Sea and the Alaska Peninsula.
The slow progression will contribute to a total rainfall for St
Paul to be around an inch from tonight through Sunday afternoon.
Elsewhere along the Aleutians could expect roughly half inch to an
inch storm total rainfall. Winds along the front are expected to
be between 15 to 25 mph with gusts to about 30 to 40 mph.

Across Southwest Alaska, skies will gradually clear for this
weekend as the ridge moves east. Afternoon showers will be
possible through the weekend from southern Bristol Bay to the
foothills of the western Alaska Range as embedded easterly
shortwaves round the periphery of the a Gulf low. Winds are
expected to be light across Southwest as the upper level flow
weakens. Convective potential will increase each day, with
isolated thunderstorms possible Sunday afternoon.

&&


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

With some small adjustments with the position and strength of the
omega block over Mainland Alaska will come from the West through
the forecast period. One upper level low center exits the Gulf of
Alaska Wednesday with little effect to the high, moving onshore
into Canada by midweek. The other low in the Bering gathers
support from the Arctic and begins its move over the West Coast.
Shortwaves around the Bering low add increased instability for the
Western half of the state. Longer term rainfall continues across
the Aleutians and Bering through the end of the workweek. Forecast
model confidence remains higher for the Interior features, and
slightly less elsewhere. Periods of locally heavy rain spreads
over Southwest Alaska and the Alaska Peninsula for late Tuesday
and is sustained more over the West as the areal coverages expands
across Kodiak Island and Southcentral Alaska through Prince
William Sound by Friday. Locally heavier rains will also extend
inland to the Alaska Range during the forecast.

The Eastern Interior and along the Alaska Range will see warmer
temperatures as the bulk of the surface high holds in place
through the Yukon Valley. A higher risk of occasionally heavier
showers and thunderstorms through the Copper River Valley are
possible through the forecast period.


- Kutz

&&

.AVIATION...

PANC...VFR conditions and light winds will persist through
Saturday morning. Turnagain Arm winds will increase saturday
afternoon and push over the terminal with gusts to 20 kts
possible Saturday afternoon.

CCC

&&


$$