Flooding in Alaska, May 3 to 14, 2024

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
529 AM AKDT Fri May 3 2024

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

The forecast for southcentral Alaska remains stratus quo. The first
frontal system and associated low that brought rain to Kodiak
Island, Coastal Kenai Peninsula, and a few other locations has
weakened and shifted out of the area... but is quickly being
replaced by another low moving from the far eastern Bering into the
Gulf of Alaska. Radar coverage shows precipitation has already
intensified a bit across the southern Kenai Peninsula. Strong
southeast flow will result in downsloping, dry conditions for much
of the western Kenai Peninsula north through Anchorage and much of
the Mat-Su Valley. This second system will bring rain a bit farther
north than the previous, with locations along the Prince William
Sound expected to receive rain (high elevation snow) from later this
evening throughout much of the weekend.

Strengthening pressure gradient across the area will yield fairly
strong southeast gap winds today and tomorrow, particularly out of
the Turnagain Arm and Knik Arm. Wouldn't rule out gusts late today
and tomorrow upwards of 30mph in far south Anchorage by Turnagain
Arm, as well as up by Palmer/Butte. Temperatures will remain near
climatological averages, with highs in the 50s for most of the
region and lows in the mid/upper 30s to low 40s.

-Brown

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days
1 through 3)...

The Flood Watch for an Ice Jam near Aniak remains in effect
through Saturday morning.

The forecast continues to be mostly on track. Showery conditions
across much of Southwest Alaska as well as the Alaska Peninsula
and Eastern Aleutians today. Colder air advects into Southwest on
Saturday, bringing chances for snow or a rain/snow mix overnight.
Additionally, gusty winds will continue over the next couple of
days. From Saturday through Sunday, the triple point low will
occlude as it moves over Southwest Alaska. At the same time, an
upper low moving into the Bering Sea from the Arctic will bring
shot of cold air. Expect rain showers to slowly diminish in
coverage through the weekend, with the potential for some snow
showers late at night/early in the morning as temperatures reach
their daily minimum. Otherwise, daytime heating should keep
precipitation as mostly rain. The other hazard to monitor will be
the return of light freezing spray along the northern and eastern
Bering Sea beginning Saturday night.

-KC/KM

&&

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

The broad upper level Bering Sea trough harboring a closed low
near St Lawrence Island will be breaking down and moving through
the Gulf of Alaska into the Eastern North Pacific by the end of
the forecast period. Forecast models demonstrate less confidence
in the changing weather pattern through the week. The occasional
injection of North Pacific energy and some jetstream support helps
bring some significant weather producers across the Aleutians. It
also helps draw the Bering low Southward beginning Tuesday. The
system forms across the Central Aleutians and continues over the
Alaska Peninsula for Thursday. An Eastern Gulf low weakens and
moves into the Canadian Provinces as a trough by Wednesday. The
upper level ridge weakens but holds on over the Arctic Coast.

Widespread precipitation will be the order of the day across the
Western and Central Aleutians for Tuesday, and the Eastern
Aleutians, AKPEN, and the rest of Southern Alaska to the Canadian
Border through the forecast. Additional rainfall should not be a
factor with Interior Rivers dealing with ice jams and flooding due
to above average snow melt. Locally heaviest rainfall is expected
to spread from the Eastern Aleutians, AKPEN, parts of Cook Inlet,
Kodiak Island, the Eastern Kenai Peninsula and over Prince
William Sound for Wednesday and Thursday. The precipitation area
continues to spread Eastward along the Gulf through the Weekend.

-Kutz

&&

.AVIATION...

PANC...VFR conditions will persist. Confidence is higher today
that strong wind out of the Turnagain Arm will reach south
Anchorage and the ANC airport. However, the forecast challenge
will be with regards to timing. Current thinking is that it'll
begin to pick up after noon. The stronger east-to-southeast
winds aloft will likely not make it as low as 2000 ft for true low
level wind shear, but there may be some wind shear above the 2000
ft level through Friday.

-Brown

&&