Alaska Extended Forecast Discussion
National Weather Service College Park MD
437 PM EDT Sat Sep 6 2025
Valid 12Z Wed 10 Sep 2025 - 12Z Sun 14 Sep 2025
...Rain and wind over the Aleutians into parts of coastal
Southcentral Wed/Thu...
...Guidance Evaluation/Preferences...
Upper pattern over the high latitudes will transition from higher
to lower amplitude from midweek into next weekend as a deep
system near/southeast of the Aleutians weakens into the Gulf.
Thereafter, upper ridging will build/hold over
northwestern/northern Canada as well as into eastern
Asia/Kamchatka, further anchoring troughing across the
mainland/155W. The models have continued to converge toward a
common solution (after a few days of stark disagreement) with the
track of the lead-in system and a blend of the latest 12Z guidance
offered a reasonable starting point. This should move the front
into southeastern Alaska/Panhandle at a bit quicker pace than
forecast 24 hrs ago, but perhaps lingering a bit near Haida Gwaii
as it runs into ridging to its east.
From Friday onward, the ensemble means all show troughing in
roughly the same longitude but the deterministic models indicate
potential for a minor shortwave to whisk southeastward on the
backside of the trough into the northern/northeastern Pacific
(south of 50N) and potentially spin up another system
near/south/southeast of the Gulf of Alaska by next weekend.
Confidence is low given the time range. A blend of the
ensemble/deterministic models showed some signs of a system near
or just north of 50N for now.
...Weather/Hazards Highlights...
With a central pressure in the high 970s or low 980s, the system
near the Aleutians should promote gusty winds over favored areas
across the archipelago and perhaps toward the AKPen, with modest
to heavier rain eastward across coastal Southcentral to around
Yakutat. This area will see the greatest moisture surge ahead of
the cold front combined with enhanced lift from the terrain.
Modest NW flow around the surface low could enhance gap winds
through the Aleutians as well on Wednesday. Rainfall totals of a
few inches are possible along the coast with several inches
(3-6"+) toward Yakutat per the NBM. For the rest of the Interior,
scattered showers will linger through the period thanks to
lingering upper troughing.
Temperatures will be below normal over the North slope, but near
to above normal over the rest of the state to start to period.
Then, temperatures will trend to near to below normal over much of
the mainland. Areas of the southeastern Alaska to the Panhandle
will see above normal temperatures ahead of the front that only
cool slightly into next weekend.
Fracasso
Additional 3-7 Day Hazard Information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can also be
found at:
https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html