Alaska Extended Forecast Discussion
National Weather Service College Park MD
744 PM EDT Sun Oct 18 2026

Valid 12Z Thu 22 Oct 2026 - 12Z Mon 26 Oct 2026


...Bering Sea low will bring high wind and heavy
precipitation/snow threats to parts of the Mainland late week...


...Overview...

Upper troughing over the eastern half of Mainland Alaska will be
weakening and shunting east to start the period Thursday, while
mean upper ridging makes its way east across the Mainland
Thursday-Friday. This is in response to a large and broad
upper/surface low in the Bering Sea that will bring strong
southerly flow for warmer temperatures, heavy precipitation, and a
high wind threat for portions of Alaska on Friday into Saturday.
This system is forecast to gradually weaken over the weekend,
though additional troughing is forecast to reach the Bering Sea
and could bring another round of active weather to western parts
of the state by early next week.


...Guidance Evaluation and Preferences...

Model guidance is remarkably agreeable on the wavy and active
large scale pattern described above during the period. Even some
shortwaves early in the period--one moving through northwestern
Alaska and another lingering near the Gulf Thursday-Friday--show
some consensus, though the GFS runs are a bit stronger and west
with the latter shortwave compared to the other guidance.
Otherwise there is good agreement that the Bering surface low
should reach into the 960s mb Thursday-Friday but weaken a bit as
it moves east into Saturday. By Sunday there is some minor spread
with the potential for some energy to shift east across the
Mainland and some to shift north/northeast, but overall a
weakening and lifting upper trough is likely. Then guidance agrees
in principle that another upper trough/low will move across
Kamchatka Sunday and into the Bering by Monday with another
surface low, with some spread in the details like the exact
position and strength, but model variations are well within reason
for Days 7-8.

The WPC forecast was able to use a multi-model blend of the GFS,
ECMWF, CMC, and AIFS through the early part of the period. Used
some ensemble mean guidance in the fronts/pressures blend by the
mid to late period, but was able to use a majority of
deterministic models throughout, given the large scale agreement.
This increases confidence in the impactful pattern taking aim at
Alaska late week.


...Weather/Hazards Highlights...

A first impactful system affecting Alaska early this week, namely
a strong low in the Gulf, could have outflow winds on its
backside lingering across southern portions of Cook Inlet into
midweek. Modest precipitation is also forecast to continue across
Southeast Alaska into Thursday and even lighter amounts are likely
into Friday. The eastern part of the state should generally see a
drier pattern underneath ridging between the two systems.

Farther west, a deep low pressure/frontal system in the Bering
Sea will bring precipitation chances to the Aleutians by Thursday,
shifting into the Alaska Peninsula and western Mainland on
Friday, and spreading east across much of the Mainland over the
weekend. A moderate to strong atmospheric river will support
potentially heavy amounts across southern areas like the Alaska
Peninsula and Kuskokwim Delta Friday-Saturday and favored regions
of Southcentral Saturday. Sufficient moisture reaching farther
north could also lead to heavy snow across southern parts of the
Seward Peninsula and western to central parts of the Brooks Range.
The warming temperatures may allow snow to turn to rain even in
the Seward Peninsula, but it could get a push of heavy snow before
any changeover. High winds will be an additional threat with this
system with strong southerly flow across the Alaska Peninsula and
across the western Mainland, and localized coastal flooding
cannot be ruled out. The wind threat looks to stretch across
portions of the Brooks and Alaska Ranges with channeling/funneling
Friday-Saturday. Precipitation could continue into Sunday for
some areas of the Mainland, but amounts should be lighter. The
next Bering Sea low pressure system may start to bring the next
round of precipitation to western areas late Sunday into Monday.

Cooler than average temperatures may prevail in the eastern half
of the Interior into Southeast Alaska late week, but the broad and
deep southerly flow will bring warmer than average temperatures
first to western Alaska and then spreading across most of the
state over the weekend. This brings highs into the 40s for the Y-K
Delta and into the 30s for the Interior. The North Slope seeing
near to above freezing temperatures as forecast would be 20+
degrees above normal for this time of year. Southeast Alaska looks
to stay within a few degrees of average.


Tate


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