976
FXAK68 PAFC 011343
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
543 AM AKDT Sat Jun 1 2024

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

A vertically stacked occluded low over the central Gulf of Alaska
will slowly retrograde to the west, reaching an area of the
western Gulf south of Kodiak Island Sunday. Its occluded front
will remain draped over the northern gulf through the weekend,
producing steady rain and easterly gales across the northern Gulf
over to Kodiak Island through Sunday morning as a series of
upper-level waves and vorticity lobes move along the front.
Steady shower activity will also continue along the immediate
Southcentral coast, especially across the higher terrain of the
eastern and southern portions of the Kenai Peninsula.

Farther inland across Southcentral, clouds and showers will be on
the increase as an upper-level shortwave out ahead of the
occluded front moves from the northern panhandle of Alaska inland
over the Copper River Basin and Susitna Valley. The increase in
clouds and scattered shower activity will keep temperatures a few
degrees cooler than what was observed Friday across interior
Southcentral.

Conditions across Southcentral are expected to improve, with
clearing skies and warming temperatures, for Sunday as the low
over the western Gulf slides a bit farther south. This jog
southward will allow a ridge to push into the interior of the
Southern Mainland. For Kodiak Island, the low, coupled with an
advancing inverted trough, will allow showers and gusty winds to
persist into Monday. By Monday, the inverted trough and associated
easterly upper-level wave will move into the eastern half of
Southcentral with another round of scattered showers likely from
the Copper River Basin Monday morning into the Susitna Valley by
Monday afternoon.

&&


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

Nighttime microphysics satellite imagery shows the continued
presence of a broad upper low across the southern Bering, closely
centered over the Central Aleutians, along with a second low
located over the Gulf of Alaska, its front crawling westward and
encroaching into the Western Alaska Range. Unchanged, high
pressure over western Canada extends into interior Alaska. Let`s
begin with the Bering low first. This low has occluded and its
front is now pushing eastward toward the coast of Southwest
Alaska. The presence of the Bering low is promoting widespread
cloud cover, a mix of low stratus and fog. Saint Paul has flirted
with 1/2 mile visibility through the morning hours. Over the next
24 hours a passing shortwave trough south of the Aleutian Chain is
forecast to pick up the Central Aleutian low and carry it into
the North Pacific through midday Sunday. High pressure will
briefly set in over the southern Bering with drier conditions
expected to become more common through Monday.

Unsettled conditions are forecast across Southwest Alaska.
Morning radar shows rain has spread across much of Greater Bristol
Bay. An area of enhanced lift has likely helped with the
development of rain as upper level forcing spreads inland from the
Bering, and additional lift moves in from the Gulf of Alaska
side. Significant degradation of the Bering low is forecast as it
moves into the North Pacific over the next 24 hours. Thus, any
shower activity on Sunday and Monday will be driven by easterly
wave activity from low pressure over the western Gulf. Models are
in good agreement with bringing the next wave southwestward across
the western half of the Greater Bristol Bay area early Sunday
morning. Additional easterly waves will serve to further enhance
rain activity Sunday into Sunday night, with much of the Lower
Kuskokwim Valley to also experience a round of precipitation
Sunday night into Monday morning.

The biggest questions for Southwest Alaska entail the potential
for thunderstorms Saturday afternoon as well as Sunday afternoon.
Any clearing that develops on either day will help promote at
least weak instability. The most favorable location for lightning
on Saturday will exist north and northwest of Dillingham later
this afternoon and evening. Sunday`s thunderstorm chances spread
northward from both sides of the Kuskokwim Mountains into the
Middle Kuskokwim Valley.


&&


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

A broad upper-level trough over the Gulf of Alaska will continue
to persist through Wednesday evening, producing easterly waves
that will carry over Southcentral. As showers form from these
waves, precipitation totals will mostly be light. However, as
increased convective activity is currently expected over the
Copper River Basin through midweek, higher local amounts of
rainfall are possible with this system. The biggest chance for
widespread and heavier precipitation will be Tuesday into early
Wednesday as the majority of easterly waves will pass over the
region at that time.

The trough will start to dissipate and merge with a new trough
in the eastern Bering and Aleutians Wednesday night. Widespread
showers will be possible over Southwest as the trough lingers over
the Bering and slowly moves westward through the remainder of the
forecast period. Stronger winds will not be a major concern since
the low will be vertically stacked and past its peak intensity.
The track of the trough by Friday and into next weekend becomes a
bit more uncertain with current model guidance. Some models are
suggesting that the trough lingers over the central Aleutians
while others shift it much further south and east well outside of
the forecast region.

-BS

&&


.AVIATION...

PANC...VFR conditions and light winds will persist.

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 the early afternoon. These winds will
likely persist through late evening before diminishing again
overnight.

&&


$$