621
FXAK68 PAFC 162358
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
358 PM AKDT Thu May 16 2024

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

A stout upper level ridge remains over eastern Alaska, with a
deep longwave trough axis situated over the eastern Bering and
southwest Alaska. A shortwave south the Alaska Peninsula rotating
around the base of this trough will close off and move eastward
over the gulf and underneath the ridge through tonight. At the
surface, an associated weak surface low near Kodiak Island will
move slowly eastward through Friday before quickly weakening. Rain
currently across Kodiak Island will continue to spread northward
into the Kenai Peninsula through tonight, quickly ending by Friday
afternoon. Behind the low, a weak shortwave ridge attempts to
build back into western Southcentral Alaska. Slightly warmer
temperatures will return on Saturday with some breaks in the
clouds possible, and much of the area remaining mostly dry
through at least early afternoon. Gusty southeasterly gap winds
through the Turnagain and Knik Arms and Copper River Basin will
also pick up again as a coastal ridge develops ahead of a low
entering the western Gulf.

Later on Saturday a robust upper level low will slide from the
Bering Sea into the western Gulf of Alaska, sending another period
of precipitation back into Kodiak Island. As the upper low and
accompanying surface low move into the western Gulf, precipitation
will also overspread the eastern Kenai Peninsula through Sunday
morning. Confidence remains low in regards to the northern extent
of precipitation through Sunday as there is still disagreement
among model guidance on where the upper low ejects into the Gulf;
a moderate, more steady rain may also make it further north into
the Prince William Sound and other areas along the coast of
Southcentral Alaska.

-ME

&&


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

The front is drifting east across Southwest and chances for
precipitation are decreasing as it pushes toward the Alaska Range
and Southcentral. Fog and low stratus could return in the morning
for the Kuskokwim Delta and coast. Meanwhile, a front is moving
across the Bering Sea with increasing chances for precipitation
expected overnight for the Pribilof Islands and the Eastern
Aleutians Friday morning. The front progresses into the eastern
Bering and the Alaska Peninsula Friday evening, where chances
linger through Saturday. By Saturday morning, the front will
extend precipitation to the Southwest Alaska coast. South to
southeasterly flow will be enhanced through gaps (to around 20 to
30 mph, gusting 25 to 35 mph) Saturday morning for Etolin Strait,
the passes and channels of the Alaska Peninsula, and Bristol Bay
Saturday. Southeast winds increase to 30 to 40 mph through
Kamishak gap Saturday afternoon and evening. Chances gradually
diminish Sunday from northwest to southeast. Slightly warmer
temperatures can be expected with southerly flow.

With the progressive pattern expected in the forecast, A ridge
will be sandwiched between systems and quiet weather will be
brief. The next front reaches the Western Aleutians Saturday
morning. Small craft wind gusts are possible, and widespread
precipitation mainly in the form of rain is currently expected as
the shortwave moves eastward. The front appears to weaken and
flatten into a more east west orientation as it passes Adak. As
such, isolated to scatter showers could linger behind the front
through Monday morning. The Pribilof Islands could also see some
light showers returning Monday morning.

rux

&&

.LONG TERM FORECAST (Days 4 through 7)...
The extended forecast looks to be a brief transitional period as
the longwave pattern reloads itself. Currently the pattern is
driven by an anchoring trough over Siberia with a cold pool
extending into the Bering Sea and southwest Mainland. Over the
weekend, a new stronger shortwave trough propagates within the
east Asian jet and into the Bering Sea which will re-orient the
longwave trough to look much the same as it currently does despite
the first system moving from the Bering Sea into the Gulf of
Alaska. For Southcentral Alaska, the northern extent of the Gulf
low pressure will potentially bring rain to coastal areas but
leave interior areas dry with continued clouds and slightly below
normal temperatures over the weekend.

What does this mean for sensible weather? Another slug of
tropical moisture will bring rain to the southwest Mainland and
Aleutians early next week along with gusty southerly winds. The
building ridge ahead of that front will bring at least of day of
drier possibly sunny weather, however, with the trough out west
positioned over the Bering Sea it is more likely than not that we
get another disturbance or moisture plume over Southcentral, but
confidence is lower and uncertainty high as the pattern
transitions. Stay tuned.

MTL

&&

.AVIATION...

PANC...VFR conditions will persist. The Turnagain wind may continue
to bend into the terminal through the evening then slowly taper
off into the overnight hours. Confidence on winds impacting the
terminal decrease as the evening goes on. Otherwise relatively
benign weather conditions are expected at the terminal.


MTL

&&


$$