410
FXAK68 PAFC 311330
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
530 AM AKDT Fri May 31 2024

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

An area of low pressure will continue to strengthen this morning
as it enters the southern Gulf of Alaska. A surface warm front
associated with this system will quickly occlude as it lifts north
into the northern Gulf by this afternoon. Widespread rain and
easterly gales will accompany the front spreading to the
immediate Southcentral coast. Farther west, strong northeasterly
winds and steady rain will continue for Kodiak Island as a
lingering trough axis over the region phases with the occluded
front while also serving as the focus for continued moisture
advection.

Farther north, expect generally clear and dry conditions from Cook
Inlet north into the Mat-Su Valleys and Copper River Basin as an
upper-level ridge builds over the region out ahead of the
aforementioned low. Subsidence with this ridge will should act to
keep any low-level and mid-level cloud cover to a minimum and
allow for daytime temperatures to push well into the 60s for many
locations, with the warmest temperatures over the Susitna Valley
and Copper River Basin. Gap winds will be the increase again
today; however, these winds are not expected to be as strong or
last as long as previous days.

The occluded front reaches the coast Saturday with rain across
the immediate coast and increasing chances for showers inland as
an upper-level shortwave ahead of the surface front moves inland.
The low center begins to track west on Saturday in response to the
longwave upper-level trough also lifting northwest. This westward
jog will allow a second round of strong winds and heavier rain
showers to move back over the northern Gulf and Kodiak Island.
The gusty winds and precipitation will likely persist across
Kodiak Island and the northwestern Gulf of Alaska into Sunday as
the low drifts slowly south of Kodiak Island.

The increasing clouds and scattered showers for interior
Southcentral Saturday will help to keep temperatures a few degrees
cooler than today. Conditions should improve again for Sunday with
only a few isolated showers as the upper level wave moves north
into the west central part of the state.

-TM

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today
through Sunday night)...

A 988 mb low in the Gulf of Alaska is extending a weak warm front
across the Alaska Range into Bristol Bay, where it is producing
isolated showers this morning. Light isolated rain showers extend
into portions of the Kuskokwim Valley, near Aniak and Kalskag,
as some mid-level moisture surges northward across Southwest
Alaska. This shower activity is forecast to wind down this
morning, giving way to a fairly warm and dry day. Northeasterly
offshore flow will bring in warmer air from Interior Alaska,
allowing high temperatures to approach and even eclipse 60
degrees at many places across Southwest Alaska. A relatively
stable environment will also mean a dry day for most places across
the region. The exception will be in the Kuskokwim Valley between
Sleetmute and Bethel, where marginal instability is expected to
support isolated to scattered rain showers this afternoon/evening.

Tonight, an occluded front off the low in the Gulf pushes across
the Alaska Range, bringing light rain into Bristol Bay. Despite
the frontal passage, warmer air continues to surge southwest from
the Interior, bringing continued warming conditions and more
unstable conditions which will be supportive of more numerous
showers across the Lower Kuskokwim Valley and interior Bristol Bay
on Saturday. There are indications that convection will continue
overnight with the support of a combination of the theta-e ridge
and easterly shortwaves tracking in from Southcentral Alaska. The
area of greatest instability shifts toward the Kilbuck/Ahklun
Mountains and potentially even into the Kuskokwim Delta for
Sunday as the low in the Gulf shifts northwest. However, there is
some uncertainty in the exact placement of the greatest
instability and therefore exactly where showers will set up.
Conditions appear, at best, marginal for thunderstorm
development, with a warm layer above 600 mb likely keeping
convection too shallow for more than a stray lightning strike or
two. Currently, though, lightning is not expected.

- Quesada

&&

.SHORT TERM FORECAST BERING SEA AND ALEUTIAN ISLANDS (Days 1
through 3: Today through Sunday night)...

An occluded gale-force low is centered just south of Agattu Island,
extending a front across the southern Bering Sea to the eastern
Aleutians this morning. Light rain is associated with the front
has begun to move into the eastern Aleutians, while rain showers
can be found near and just east of the low center pushing through
the western Aleutians. The low is forecast to gradually moves
east and weaken, its front crossing the Pribilof Islands and
moving into the Alaska Peninsula today before shearing out over
the eastern Bering Sea on Saturday morning. Light rain showers
near the center of the low track east along the Aleutian Chain
through Saturday as well, before dipping back into the North
Pacific. Much calmer and drier conditions are in store for the
Bering Sea and Aleutians on Saturday despite a broad trough
lingering behind the exiting low. This is short-lived, however, as
northerly winds increase over the western Bering/Aleutians in
response to the remnants of Typhoon Ewiniar passing well to the
south of the Aleutians on Sunday. Northerly winds spread eastward
to cover much of the Bering for the start of next week, but remain
below gale force.

- Quesada

&&


.LONG TERM FORECAST (Days 4 through 7) Monday through Thursday...

The Alaskan upper level map opens with a closed low to the South
of the Alaska Peninsula beginning its track around the Gulf of
Alaska. It draws closest to Southcentral through Wednesday before
curving past Kodiak Island into its exit for the end of the
forecast period. A second low center tracks out of the Arctic
along the West Coast late Tuesday before swirling out and stalling
in the Central Bering by Thursday. Several surface troughs rotate
over the Western Bering through Thursday. Jet stream support has
pushed further South. A weak upper level ridge holds over the
Central and Northern Mainland, and looks to support surface
thermal troughs, especially across the Central Interior.

Gusty Northerly winds are expected over the Eastern Bering as the
Arctic low moves through, diminishing late Tuesday. Showers
spread over the Bering, Southwest Alaska, AKPEN and the Aleutians.
Easterly to Southeasterly airflow over the Southcentral Alaska
spreads moisture as far North as the Alaska Range, and from the
Canadian Border across Prince William Sound and the Kenai
Peninsula. Locally heavy showers will come with each Easterly
wave, otherwise periods of light rain are expected. Potentially
larger amounts of rain over the Copper River Basin associated with
more convective events are expected.


-Kutz

&&
.AVIATION...

PANC...VFR conditions and light winds will persist through early
afternoon. Gusty winds are expected to pick back up out of the
south from Turnagain Arm by mid afternoon. These winds will
likely persist through late evening before diminishing again
overnight.

&&


$$