711
FXAK68 PAFC 220123
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
523 PM AKDT Mon Jul 21 2025

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

A strong ridge in the North Pacific flattens and migrates
eastward allowing for multiple troughs and southwestward flow to
move over Southcentral Alaska through mid-week. Widespread
increasing gap winds and precipitation chances are expected.

Today, clouds over many areas of Southcentral dissipated as more
of a westerly to southwesterly wind component dominated. Places
in the Kenai Peninsula and portions as far north as Anchorage saw
prolonged periods of sunlight today. North of Anchorage, areas of
Prince William Sound and the Copper River Basin remained mostly
cloudy today as a more northerly component of the wind kept the
drier, aforementioned southwesterly flow from reaching those
locations. Additionally, scattered rain showers were present in
these areas today.

This evening into Tuesday afternoon, offshore, westerly winds
prevail leading to gusty gap winds through the Barren Islands and
Cook Inlet. Gusts ranging from 35 knots to 45 knots with wave
heights 6 to 10 feet are expected. Winds in the Homer outer waters
and closer to the Homer spit will also increase ranging from 30
to 35 knots and from 25 to 30 knots respectively beginning Tuesday
afternoon and continuing through late Wednesday evening at the
earliest. Wave heights range from 8 to 10 feet in the outer waters
and 4 to 6 feet closer to the Homer spit. A slight southwesterly
wind through Shelikof Strait causing gusts there ranging from 20
to 30 knots and wave heights ranging from 4 to 8 feet are expected.

A trough moves across Southcentral Tuesday afternoon as the Gulf
of Alaska High flattens further resulting in a more zonal flow
from west to east. The trough reaches Southcentral late Tuesday
afternoon. The trough will bring a reinforced period of offshore
winds through the Barren Islands and Cook Inlet. As the trough
moves through the Copper Basin, it deepens, both as a result of
the westward progression of the Gulf of Alaska high and an
eastward moving low in the Chukchi Sea. This deepening the continued
likelihood of rain mid-week. Rainfall amounts range from 0.5 to
1.0" on Wednesday in the Copper Basin.

&&

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

The story in Southwest Alaska is similar to yesterday, with
persistent southwesterly flow over the entire region. A large
upper level low near the Seward Peninsula will continually swing
shortwaves through Southwest Alaska for the next few days, being
the main driver of weather. A shortwave from this upper low passes
through the Kuskokwim regions increasing rain chances. Bristol
Bay is drier, with some areas of clearing skies. The Bering is
under a slight ridge, allowing for continued low stratus and areas
of fog, particularly in the Pribilof Islands. Another short wave
moves through the Pribilof Islands and then the Southwest mainland
by Tuesday afternoon. This will drive up rain chances for much of
the southwest mainland. Greater rainfall totals will be seen
closer to the coast in the Kuskokwim Delta region. Much of the
Bering west of Bristol will remain under a ridge, keeping wind
speeds and rain chances down. Yet another shortwave will move into
the Southwest mainland on Wednesday. Impacts will be similar to
Tuesday`s shortwave.

Finally, the large low itself decides to dive southward and enters
Southwest Alaska on Thursday. This is due to the ridge in the
Bering strengthening and increasing in area, and a weaker
shortwave from Kamchatka helping to pull it down. Depending on
how this plays out, Southwest Alaska may receive widespread heavy
rainfall in excess of 1 inch in some regions (high terrain and
coastal areas). Wind speeds will also crank up, with the
Kuskokwim Coast and Bristol Bay seeing onshore winds up to small
craft. Gusty westerly winds blow into the Kamishak Gap near
Illiamna. There is much uncertainty with the exact scenario as
model disagreement is high. Some models have the low dropping
later while others don`t have it dropping at all. What is known is
that rain chances will increase toward the end of the week.

-JAR

&&

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

Models indicate the upper level low, currently over the North
Bering Sea, will emerge from the center of the state and into the
Gulf of Alaska towards the end of the workweek. This area of low
pressure will slowly meander across the Gulf through the end of
the period. All of the Global models come to this scenario. This
will bring shower precipitation across the Alaska Range and
southern and southeast coast of the state. High pressure will
ridge into the Bering Sea and Aleutian Islands from the North
Pacific and extend across the western portion of the state. Some
uncertainty does exist with a potential upper level trough moving
into the western portion of the state, from the Bering Straight,
towards the end of the forecast period.

-DD

&&


.AVIATION...

PANC...VFR conditions will likely persist through early Tuesday
morning, with ceilings around 5,000 ft. A scattered deck around
2,500 ft is also possible, with the bulk of lower clouds situated
north and east of the terminal. A weak shortwave will move over
Cook Inlet beginning 9z. This feature will bring an increase in
lower clouds, and perhaps a few sprinkles, with ceilings likely
falling to between 2,500 ft and 3,500 ft after midnight. Light
west to northwest winds will persist through Tuesday.

&&


$$