Crow Pass Trail, Alaska Weather Forecast Discussion

949
FXAK68 PAFC 302344
AFDAFC
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
344 PM AKDT Tue Sep 30 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...
The upper-level trough that brought an area of light snow
overnight and this morning along portions of the northern and
eastern Copper River Basin is exiting the region this afternoon.
In its wake, a ridge is building in from the west keeping
conditions cool and dry across most locations west of Prince
William Sound.
Skies will remain mostly clear through through late tonight from
the Kenai Peninsula north into the Susitna Valley, allowing for
widespread 30s for the overnight low. However, a frontal system
will move in from the west by early Wednesday morning, bringing
both an increase in cloud cover and southeasterly gap winds
through Turnagain Arm and the Knik River Valley. The combination
of increased clouds and wind will allow for temperatures to warm
in advance of the precipitation associated with the front.
The aforementioned precipitation will overspread the Susitna
Valley by mid-morning Wednesday and late-morning to early
afternoon for the Kenai Peninsula, Anchorage Bowl, Mat Valley, and
Prince William Sound areas. A strong south to southwest flow along
the front and upper-level trough will allow precipitation to fill
in over Cook Inlet, with the heaviest precipitation for upslope
areas of the northern Susitna Valley, Hatcher Pass, and Kenai
and Chugach Mountains. Snow levels will rise from around 2,500
feet or so Wednesday morning to around 3,500 ft by afternoon.
Thus, any snow accumulation will be confined to the mountains as
well as the northern half of Broad Pass and the extreme northern
and western Copper River Basin.
As the upper-level wave drives into Southwest Alaska late
Wednesday, a new surface low will spin up near southern Cook Inlet
and drive east through Thursday. This new system, along with its
upper-level support, stout moisture advection and southerly winds
aloft, will drive ample moisture and precipitation into the
northern Susitna Valley, Talkeetna Mountains, Prince William
Sound, and Chugach Mountains through late Thursday. Upwards for an
inch or more of rain is possible around Talkeetna with less than
an inch from Kenai to Anchorage and Palmer. Closer to 2 to 3
inches of rain is likely from Valdez to Cordova, with locally
higher amounts at elevation.
For locations that do see cooler temperatures and snow potential,
light accumulations, on the order of 1 to 3 inches, is possible
for Paxson and Eureka. 6 to 12 inches of snow could fall at
Summit Lake in Hatcher Pass. What`s that saying?...Winter is
coming!
As the low moves into then east of Prince William Sound, the
southerly gap winds, with gusts around 30 mph for parts of
Anchorage, the Matanuska Valley, and Copper River Valley, will
quickly diminish then become more northerly as colder air moves
in behind the low. Westerly and northerly gap winds are then
expected for Whittier and Seward, respectively, by Thursday
afternoon and lingering into Friday as precipitation quickly
comes to an end from west to east.
-TM
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days
1 through 3/Tonight through Friday)...
The upper level flow is quite progressive, which will lead to
changing weather conditions as a series of storms crossing the
region this week. Taking a look at satellite imagery, a large
vertically stacked low is spinning over the northwestern Bering
Sea (just offshore of Siberia). A strong short-wave is driving the
trough eastward toward western Alaska, with a surface cold front
approaching the Kuskokwim Delta this afternoon. A narrow band of
rain and southerly winds gusting 25 to 35 kt is being observed
just ahead of the front. The cold front extends southward across
the eastern Bering then wraps back to the west across the southern
Bering Sea in a much weaker state. This is due to the presence of
a gale force low south of the western Aleutian Islands. This has
taken a more northerly track then expected in previous days, with
steady rain and stronger winds (25-30kt) headed for the Aleutian
Islands.
Both storm systems will progress eastward tonight through
Wednesday. Short-waves will dig down the back side of the Bering
low, amplifying the low and interacting with the Pacific storm
system. This will reinvigorate the stalled cold front over the
southern Bering tonight and then steer the front back to the
south and east Wednesday through Wednesday night. The resultant
weather from both these systems will be rain spreading inland
across Southwest AK and across the Aleutian chain and Alaska
Peninsula. A quick shot of cold air advection with cold front
passage will lead to gusty northwesterly gap winds for the
Eastern Aleutians and Alaska Peninsula Wednesday night through
Thursday. Rain could be locally heavy at times along the northern
Alaska Peninsula (Port Heiden to King Salmon) and continuing
northward along the west side of the Aleutian and Alaska Ranges
as the upper trough amplifies Wednesday afternoon/evening.
Showery weather will settle in behind the cold front, especially
over Southwest AK as the cold upper trough moves overhead.
There will be a brief break in impactful weather Wednesday night
through Thursday as a flat ridge moves through, with zonal flow
aloft and just some very weak short-waves embedded in the flow.
Attention will then shift to a storm system crossing the northwest
Pacific on Thursday. A series of Arctic troughs will dig southward
to the west of this storm, amplifying the pattern and leading to
a strengthening of the surface low as it crosses the western
Aleutians into the Bering Sea on Friday. Another upper low and
trough will exit Siberia and move into the northern Bering Sea at
this time. The end result will be widespread rain and wind across
the region late this week and into the weekend.
With so many features interacting with each other in the upper
atmosphere, there is automatically some uncertainty in timing and
track of the main surface low. The most likely track based on
latest deterministic and ensemble model guidance is northward
across the Bering Sea and toward the Bering Strait. This will bear
watching as it is the ideal storm track to produce storm surge
flooding along the west coast of Alaska - including the Kuskokwim
Delta.
&&
.LONG TERM FORECAST (Days 4 through 7: Saturday through
Wednesday)...
The weekend starts out with a deep upper level low/trough
extending from the Chukchi Sea through the Bering Sea, Western
Aleutian islands and into the North Pacific with troughs rotating
through the region. These troughs will produce potentially strong
surface features, keeping the conditions unsettled across the
area. A significant deepening 970 mb low will cross the Bering
Sea before weakening slightly as it moves towards the Bering
Strait and Western AK Sunday and into Monday. The main concern
with this system will be possible gale force winds across the
Western Aleutians and steady strong southwesterly winds and
coastal erosion in the communities along the central west coast
of the state.
A second Sea of Okhotsk low will quickly pass over the Aleutians
and southern Bering sea and cross the Alaska
Peninsula on Tuesday then track northwestward to the Gulf of
Alaska impacting Southcentral towards the end of the forecast
period. There is a potential to see gale force winds and heavy
precipitation with this system as it passes over the Aleutians and
Bristol Bay and along the Gulf coast. Some snow accumulation
above the Pass levels is possible.
&&
.AVIATION...
PANC...Clouds will increase through this afternoon with overcast
conditions expected by the overnight hours. It will remain dry
through early tomorrow morning. A front arrives late overnight
bringing rain, wind gusts ranging from 15 to 25 knots and
ceilings ranging from 3000 feet to 5000 feet through the day.
&&
$$

NWS AFC Office Area Forecast Discussion