821
FXAK68 PAFC 240055
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
455 PM AKDT Thu May 23 2024

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

Low stratus around Cook Inlet mixed out this morning, allowing for
some daytime heating to kick off cumulus/rain shower development,
especially over the southern Susitna Valley and the western Kenai
Peninsula. Isolated to scattered rain showers will continue
through the evening until the sun angle becomes too low to support
sufficient surface heating. Further east, a weakening front over
Yukon and extending into Interior Alaska is producing steadier
rainfall north and east of the Wrangell Mountains, for locations
including Mentasta Lake, Nabesna, and Chisana. These locations
have seen around half an inch of rain since this morning. This
rain will taper off through the evening hours and overnight
tonight as the front exits to the north and east.

The weak ridge contributing to relatively drier, sunnier
conditions for most of Southcentral will shift quickly eastward
tonight, as a low tracking into southern Alaska from the Bering
Sea moves in behind. This will bring cloudier conditions and
another round of precipitation to Southcentral into the weekend.
Rain chances return for much of the area on Friday, though the
heaviest, most persistent precipitation will occur along the north
Gulf coast. The front will attempt to move up Cook Inlet on
Friday, making rain a near certainty for much of the western Kenai
Peninsula, though the front weakens through the day as it pushes
north. As a result, Anchorage and the Mat-Su Valleys will likely
see much lighter, spottier precipitation.

As a triple point low develops along the front in the Gulf on
Friday, a weak coastal ridge builds. This will drive southerly
winds through the typical gaps, including Turnagain Arm, the Knik
River Valley, and the Copper River Valley. The low shifts into the
central Gulf Friday night, allowing the coastal ridge to relax and
gaps winds to diminish. 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 on Friday night.

The low`s front lingers along the coast, keeping these areas wet
through Saturday, though the low weakens for Sunday, allowing for
conditions to dry out. Further inland, a shift to northerly flow
as the low tracks into the Gulf will lead to some drying and
breaks in the clouds heading into the weekend. The one exception
looks to be an upper-level easterly wave which tracks across the
Copper Basin on Saturday, bringing further rainfall. The wave
shears apart as it tracks west, meaning much of the precipitation
does not look to make it past the Talkeetna/Chugach Mountains,
though a chance for precipitation remains.

- Quesada

&&


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

A Bering low will continue to move eastward reaching Bristol Bay
tomorrow and the Gulf of Alaska Saturday. Frequent rain showers
will persist in the Southwest and Alaska Peninsula through
tomorrow evening with scattered showers afterward into early
Saturday morning. Wet snow could mix in with the rain showers in
Mekoryuk-Toksook Bay-Kipnuk area his evening. The heaviest
precipitation through tomorrow afternoon is expected in Southwest
Alaska. The area of heaviest precipitation will shift southward to
the Alaska Peninsula afterward through Saturday morning.
Widespread fog could develop this evening into tomorrow morning.
Westerly wind gusts along the Aleutians will range from 35 to 45
mph through tomorrow evening before becoming more northerly to
northwesterly for Saturday. Cooler temperatures in the Aleutians
are also expected as a result of the northerly winds this weekend.
Clearing skies are expected with the switch to northerly to
northwesterly winds Saturday evening and Sunday in interior
Southwest Alaska.

A Kamchatka low will bring a front through the western Aleutians
reaching Adak as early as Sunday morning. Ahead of this,
southwesterly winds will signal a warmer and less cooler period
for Sunday in the Central Aleutians.

-DJ



&&

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

The Alaska Weather Map is under a very broad area of upper level
lows, with three separated centers. The first is a weakening
center in the Southern Gulf of Alaska/Northeast Pacific that is
drifting Eastward. The second is a somewhat energetic center
meandering around the Bering Strait. The weakest of the three is a
center in the Western Aleutians and Bering. The main focus is
along the Southern portions of the state with additional energy
that arrives via the North Pacific through the forecast period.
The Northern low center contributes to weather producers over
Western Alaska. Model confidence is good with a deterministic
blend changing over to a one-half ensemble blend by midweek. The
end result is an elongated areas of low pressure extending across
the Bering into the Gulf for Thursday.

Overall looking at a good mix of sunny breaks and wetter weather.
Periods of rain spread across Southcentral Alaska to just North
of the Alaska Range through Thursday. A well developed front
brings locally heavy rain over the Aleutians and Bering, spreading
into Southwest Alaska late Wednesday. A second well developed low
and front bring another round of locally heavy rain into the
Western Aleutians and Bering late Wednesday into Thursday.


- Kutz

&&
.AVIATION...

PANC...VFR conditions are expected through Friday morning. A
slight increase of west to southwest winds from Cook Inlet with
the sea breeze could occur through this evening, until about 06Z.
Otherwise, light south to southwest winds will prevail.

&&


$$