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FXAK68 PAFC 050046
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
446 PM AKDT Tue Jun 4 2024

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

The forecast remains generally on track with an eastern Gulf low
set to move northwestward over the next day or so. This low will
drag an easterly wave out of the Yukon and through interior
Southcentral Alaska, starting with the Copper River Basin late
this afternoon into the early evening hours. A strike or two of
lightning is possible for portions of the northern Copper River
Basin late this afternoon into early evening before the showery
regime transitions to steady rain. This steady rain will work from
east-to-west overnight tonight and through Wednesday. Most of the
interior, including Anchorage can expect anywhere from 0.25" to
0.75" of rain from this system. The highest totals are anticipated
across the Mat-Su Valleys and western Copper River Basin, with
lesser amounts toward the Western Kenai Peninsula.

Turnagain Arm winds look to bend into Anchorage tomorrow afternoon
as coastal ridging builds with the advance of the Gulf low. These
southeast winds could persist through Thursday with the gustiest
conditions being during the afternoon and early evenings of
Wednesday and Thursday.

Additional shortwaves will continue to lift to the coast through
Thursday which will help keep rain going for much of Prince
William Sound, the Northern Gulf Coast, and the Eastern Kenai
Peninsula. Showery conditions look to wane towards Friday
afternoon and evening with perhaps a nice start to the weekend.
However, there are some indications of a stronger North Pacific
low lifting northward to the vicinity of the Gulf for this
weekend, but confidence is very low regarding its track and
evolution at this time.

&&


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

An arctic upper low tracks south through the Bering through
tomorrow, ushering in an anomalously cold airmass with it. A
surface shortwave trough originating out of eastern Russia will
accompany on the western periphery of this upper low. As it skirts
west of the Pribilofs through early tonight, the trough will
develop into a weak closed low at the surface as it continues into
the southern Bering Sea. This will bring a period of steady rain
showers to the Central Aleutians/Unalaska Island area tonight.
Confidence is still low as to whether any showers clip the
Pribilof Islands (particularly St George Island), but thermal
profiles support snow should a shower move through early tonight.

By Wednesday morning, the low will be over the eastern Aleutians
and the Alaska Peninsula, bringing the cool air with it under
northerly flow. Snow showers are expected behind the main trough
for the Pribilofs. Precipitation for the eastern Aleutians and the
Alaska Peninsula will start off as rain, but as the colder air
advects southward, rain will switch to snow Wednesday night. Mixed
precipitation could potentially extend as far west as the central
Aleutians Wednesday night into Thursday morning. Some chances of
precipitation could spill over those mountains into the Kuskokwim
Valley. Showers will gradually decrease throughout Thursday for
most places across the Bering, Aleutians, and Southwest Alaska as
the low meanders and weakens. A few isolated thunderstorms are
possible for the western Alaska Range late Thursday
afternoon/evening as a few easterly waves move through with
marginal instability.

High temperatures for the Pribilofs and Aleutians will struggle
to make it out of the upper 30s to lower 40s over the next few
days. Temperatures for Southwest Alaska however will trend warmer
with highs climbing into the 50s, with 60s inland by this weekend.

-ME

&&

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

The upper level Alaska map continues under an elongated trough
stretching from Siberia across the Bering into the Gulf of Alaska
with low centers moving within the pattern. The first low center
in the Eastern North Pacific weakens and merges with a second low
coming over the Eastern Aleutians. This second low in the Eastern
Aleutians loses its energy from the North and begins an Eastward
track into the Gulf through the forecast period. A weak ridge over
the Western and Central Bering interrupts additional support from
the Russian Far East in the short term. A second weak ridge
continues its hold over the Central and Northern Mainland, which
support surface thermal troughs through Tuesday.

The reconstituted low center in the Gulf spreads easterly waves
across Southcentral Alaska, bringing onshore flow over the North
Gulf Coast. Expect locally heavy showers from the Canadian Border
to Kodiak Island through early next week. With the low center`s
closest approach to the coast, gusty winds spread across the
Copper River Delta and just outside of Prince William Sound for
Monday, diminishing Tuesday. Gusty winds will occur from Sitkinak
across the Shumagin Islands to the Eastern Aleutians on Sunday.
Showers will extend along the Aleutians through Tuesday.


-Kutz

&&
.AVIATION...

PANC...VFR conditions and light winds are expected to prevail
through Wed morning. Ceilings will begin to increase in coverage
and decrease to MVFR after 12Z with rain starting to move into the
Anchorage Bowl and terminal by 15Z. Periods of light to moderate
rainfall will allow for dips in visibility after 15Z.

&&


$$