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.

&&


$$

957
FXAK67 PAJK 220559 AAA
AFDAJK

Southeast Alaska Forecast Discussion...UPDATED
National Weather Service Juneau AK
959 PM AKDT Mon Jul 21 2025

.UPDATE... After the 06z TAF issuance the Aviation plans continue
on track. Marine deck clouds have made its way to Gustavus this
evening. This is the main change from the 00z issuance.


&&

.PREV DISCUSSION...ISSUED AT 246 PM Mon 21 July...

SHORT TERM.../Through Tuesday night/ Mostly clear skies and warm
temperatures are the rule of the day for most areas. The
exceptions are the NE gulf coast and Cross Sound areas where
marine layer clouds are keeping things much cooler in those
locations. Several inland locations in the south have reached 80
degrees or higher already this afternoon including on Annette
Island which was added to the heat advisories for today.

Through Tuesday night, cloud cover and how it will affect
temperatures is the main concern. Marine layer clouds will
continue to effect the outer coast through the period resulting in
lower high temperatures there, especially from Cape Edgecombe
northwestward. For the inner channels, today is expected to be the
warmest day. Tuesday is also expected to be warm, but with flow
changing to slightly onshore again and some higher level cloud
cover possible over the area, high temperatures are not expected
to get as warm as Monday. Widespread 60s and 70s will be the norm,
but 80+ is not expected. Sea breezes will also still be in effect
during the afternoons with localized areas possibly seeing up to
20 kt winds at times.

Late Tuesday night may see the return of some light rain for the
outer coast NW of Sitka and the Icy strait corridor from
thickening marine layer cloud processes. Expecting more light
rain/drizzle so rainfall amounts will likely be rather light.

LONG TERM.../Wednesday through next weekend/ The upper level
jet stream pattern will be changing for the mid to long term as
the persistent ridge over the gulf flattens with a westerly jet
being directed at the northern panhandle by Wednesday then sliding
southward. This will translate to the surface seeing some more
clouds (marine layer clouds likely to be pushed in) and
increasing chances of showers, although forecast confidence on
this part is on the lower end. Also, with that west wind, places
on the lee side of the mountains (Chatham Strait and other inner
channels/valleys) will likely still have some good sunny breaks,
but not as warm as Sunday/Monday.

The W-NW jet continues to be directed at the panhandle through
Friday with short-waves passing through, brining more potential
for rain showers. A more pronounced digging trough looks to move
out of the interior into the gulf for the end of the week,
becoming a closed low over the northern gulf on Saturday. This
will set up a front approaching the area with greater chances for
widespread rain. Slight differences in the track of the low will
be the difference in wet/dry across the north, the south
(particularly the southern outer coast), should see rain either
way. The large area of low pressure in the gulf looks to hold
through the weekend, which likely means continuing active weather
in the outlook.

&&

.AVIATION...Marine cloud deck out over the Gulf of Alaska Waters
that moves into the coastal locations like Yakutat, Sitka and
possibly Klawock. Lower clouds spread into Cross Sound and may
push into Gustavus area. Should see clouds burn back away from
coastal areas with solar heating Tuesday.

Predominately clear skies across the inner channels Monday
evening, to Tuesday morning. Sea Breeze winds in the afternoon to
early evening and reforming Tuesday may have some localized
turbulence.

&&

.MARINE...Inside water: Sea breeze circulations remain the main
concern for the inner channels for the next few days mainly during
the afternoons and evening. Some of these sea breezes could reach
20 kt at times. Otherwise winds are mostly 15 kt or less across
the inner channels with seas of 3 ft or less.

Outside Waters: Generally W to NW winds of 15 to 20 kt rule the
gulf with some areas (central gulf and near shore waters off
Prince of Wales Island) reaching 25 kt winds. Highest seas have
been off Prince of Wales Island with combined seas up to 8 ft.
Most of that has been wind wave while there has been a small swell
(4 ft S swell of 15 sec). Winds generally will be staying around
15 to 25 kt out of the W across the gulf for the next few days.
Seas however will be building to up to 10 ft across the central
gulf over the next few days as waves from the strong gap flow in
the western gulf work their way into the eastern gulf.

&&

.HYDROLOGY...The warmer temperatures across the northern
panhandle is increasing melt water runoff from glaciers and any
remaining snow at higher elevations through Tuesday. As of this
morning the Chilkat River did reach bankfull and warm temperatures
continue today. The flood watch that was out for the Chilkat
River has been changed to a Flood Advisory as minor flooding is
expected to start late tonight and will likely last into Thursday
before cooler weather drops river levels back below minor flood
stage.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ641-642-661>664.

&&

$$


SHORT TERM...EAL
LONG TERM....Ferrin
AVIATION...Bezenek
MARINE...EAL
HYDROLOGY...EAL


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