905
FXAK68 PAFC 250050
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
450 PM AKDT Fri May 24 2024

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

A low in the Gulf of Alaska is pushing a weakening occluded front
along the north Gulf coast, bringing rain to much of Prince
William Sound and areas eastward. Precipitation associated with
this front has been less than previously forecast for locations
inland of the coastal mountains, which has allowed for (limited)
breaks of sun and the development of rain shower activity across
portions of the western Kenai Peninsula and southern Susitna
Valley instead. A coastal ridge has also led to gusty southerly
winds through the Copper River Basin, while gap winds through
Turnagain Arm and the Knik River Valley are expected to pick up
this afternoon/evening. These winds relax later tonight as the
low shifts into the central Gulf tonight, allowing the coastal
ridge to weaken. Cooler air aloft accompanies the low, which will
drop snow levels to around 2500 ft through much of the coastal
mountains. The main impact will be potential for light snow
through Thompson Pass tonight.

The low`s front pulls away from the coast by Saturday, allowing
the area to see an end to precipitation likely during the morning
hours. Further inland, a shift to northerly flow as the low
tracks into the Gulf will lead to some initial drying and breaks
in the clouds to start the weekend. Warmer temperatures in the
lower levels of the atmosphere will also contribute to high
temperatures in the upper 50s to lower 60s for most of the inland
lower elevations. This will contribute to an unstable atmosphere
which will likely trigger potent rain shower activity in the
Copper River Basin and portions of the Susitna Valley Saturday
afternoon/evening. An isolated lightning strike or two from a
particularly strong shower cannot be ruled out. Southwesterly
storm motion combined with upper-level support from a shortwave
dropping south across the Alaska Range may allow for some rain
showers to push into Anchorage and the western Kenai late Saturday
evening into the overnight hours.

Then, an upper-level low dropping from south the North Slope will
interact with the low lingering over the Gulf and one or more
easterly shortwaves tracking in from Yukon. This produces a
fairly uncertain forecast for Sunday and beyond, though the
combination of features will provide support for rain showers and
likely some steadier rainfall at times nudging into the
easternmost portions of the forecast area as early as Saturday
night. These precipitation features will propagate generally east
to west, with the most likely areas to see over a tenth of an
inch of rainfall in the Copper River Basin. However, there is
moderate potential for this heavier rain to reach the western
half of Southcentral late Sunday and heading into next week.
Regardless, expect continued generally cool and cloudy weather
with the occasional break of sun as well as the occasional shower.

-Quesada

&&


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


An elongated trough through the Bering Sea will help to push the
Bering Low that has been impacting the region this week into the
Gulf of Alaska by tomorrow morning. The widespread effects of this
low including gusty winds, rain/snow showers, low clouds and fog,
will end overnight into tomorrow morning for most of Southwest
Alaska and the Alaska Peninsula from north to south. As the low
moves south and east, northerly winds will persist in the
Aleutians and coastal areas of Southwest Alaska. These northerly
winds will produce scattered rain showers for the northern side
of the Aleutians and coastal areas of Southwest Alaska tomorrow.
A Kamchatka Low brings its front to Shemya and the Western
Aleutians as early as tomorrow morning. Its progression eastward
will be slowed as weak high pressure moves into the North Pacific
resulting in a ridge over Central Aleutians. This ridge could
allow for warming temperatures for Sunday; ahead of the Kamchatka
Low`s eastward migration.

Weak northeasterly winds are likely tomorrow afternoon into
Sunday resulting in interior flow. Model trends the past few days
have consistently showed a weak shortwave moving through the
Kuskokwim Delta tomorrow afternoon into the evening hours. This
wave, aided by breaks in clouds, could result in isolated
thunderstorms for Bethel and surrounding areas late in the
afternoon into the mid-evening hours.

-DJ

&&

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

The long term begins Tuesday with weak deformation and troughing
remaining over Southcentral and a transient ridge moving from the
AKPen and eastern Aleutians toward Southwest Alaska. The weak
troughing over Southcentral will lend to continued shower activity
across the region, mainly across the mountains and interior
portions of Southcentral. The ridge continues east for Wednesday,
helping bring a temporary reprieve to the extensive cloud cover
and shower activity. However, the ridge quickly moves to the
Alaska Panhandle as the upper-level trough, anchored by an upper-
level low and associated surface low, reestablishes itself over
the eastern Bering and Aleutians by late Wednesday. The result
will be a return to widespread cloud cover and precipitation
moving from the AKPen Wednesday afternoon across almost all of
the Southern Mainland through Thursday. The broad long-wave trough
remains in place with continued unsettled weather and cooler
temperatures through the end of the week and into the start of
next weekend.

- TM

&&

.AVIATION...

PANC...VFR conditions are expected persist throughout the TAF
period, but occasional dips to MVFR are possible. A frontal
system will move up into Southcentral later this afternoon,
bringing with it the potential for light rain showers and/or
sprinkles to the terminal along with possible ceiling reduction
below 5000 ft. Turnagain Arm winds are likely to develop and bend
into Anchorage late this afternoon and evening, with southeast
gusts up to 25 kts possible until winds diminish later tonight.
Winds are expected to diminish by early Saturday morning then
shift out of the north. MVFR ceilings are also possible overnight
into early Saturday morning. However, confidence is low regarding
this solution.

&&


$$