Alaska Extended Forecast Discussion
National Weather Service College Park MD
700 PM EST Mon Nov 17 2025

Valid 12Z Fri 21 Nov 2025 - 12Z Tue 25 Nov 2025

...Synoptic Overview...

During the course of the extended period, an increasingly
amplified upper air pattern is forecast to establish across the
Alaska domain. This pattern will begin will a cyclone gradually
weakening over southwestern Alaska and the Gulf of Alaska followed
an increasingly negatively-tilted upper trough moving into the
Bering Sea and the Aleutians Sunday into Monday in conjunction 
with the establishment of a pronounced omega block across mainland
Alaska into the Arctic Ocean. Meanwhile, an arctic surface high 
pressure system is forecast to establish across eastern mainland 
Alaska into the Yukon Territory.


...Guidance Evaluation/Preferences...

With the increasingly amplified upper air pattern as noted, the
deterministic guidance exhibits greater than normal divergence
across the Alaska domain as the forecast extends into the weekend
and into early next week. Nevertheless, the ensemble means from
the major global models show decent agreement on this pattern
evolution out to Day 8, with a solid signal for an increasingly
amplified omega block sliding east into mainland Alaska by early
next week. The EC ensemble mean is the most pronounced ensemble
guidance compared with the GEFS mean and the CMC mean. The
ensemble trend has also supported a more pronounced and amplified
pattern heading into early next week for the Alaska domain.

The WPC medium-range forecast package is based on the consensus
blend of 40% from the 06Z/12Z GFS and 12Z GEFS, 40% from the 12Z
ECMWF and 00Z EC mean, and 20% from the 12Z CMC and CMC mean,
skewing markedly toward the consensus of the ensemble means on
Days 7 & 8. This blend yielded solutions that are quite
compatible with yesterday's WPC forecast package.


...Weather/Hazards Highlights...

Impacts associated with a cyclone sliding across the Alaska
Peninsula into the Gulf late this week will support the threat of
high winds along the southern and southeastern coastal sections,
with the South Central being the most likely location of receiving
heavy precipitation on Thursday, and the Peninsula to Kodiak 
Island being the locations for high winds. These conditions are
expected to gradually subside through the weaken as the cyclone
weakens.

Tight pressure gradient ahead of the next cyclone will likely 
bring gale to possibly storm force southeasterly winds into the 
Aleutians late in the weekend as the upper air pattern amplifies. 
The pronounced omega block establishing over mainland Alaska will 
block the eastward progress of the cyclone and deflect it 
northward into the Bering Sea. Meanwhile, an arctic high pressure
system is forecast to establish over eastern mainland
Alaska into the Yukon Territory this weekend into early next week
under the eastern branch of the omega block, where gradually
colder conditions can be expected. Otherwise, much of the
remainder of Alaska will remain milder than normal.


Kong




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