Alaska Extended Forecast Discussion
National Weather Service College Park MD
753 PM EDT Tue Oct 14 2025
Valid 12Z Sat 18 Oct 2025 - 12Z Wed 22 Oct 2025
...High winds and heavy precipitation for the Aleutians and
Alaska Peninsula this weekend and possibly spreading eastward...
...Overview...
A broad upper low is forecast to be in place atop eastern Siberia
into the Bering Sea this weekend into next week, with rounds of
potentially impactful cyclones on its periphery. First, a spoke of
the upper trough and possible embedded upper low will bring a
surface low pressure/frontal system into Southeast Alaska over the
weekend, with moderate precipitation. Another large surface low
is forecast to pass near the Aleutians this weekend for
potentially high winds and rain. The cyclone track is uncertain
after that, but areas of southern Alaska could see enhanced winds
and rain into next week. Additional energy looks to track from the
Kamchatka into the Bering Sea next week with yet another
potential surface low.
...Guidance Evaluation/Preferences...
Model guidance shows reasonable agreement with the first
upper/surface low pressure system moving into Southeast Alaska and
British Columbia over the weekend. Then most model guidance shows
a notably strong surface low (generally in the 950s or 960s mb)
impacting the Aleutians this weekend as well--at least multiple
ECMWF, GFS, and UKMET runs show this. CMC runs with a much weaker
low farther north seem to be outliers with weaker and displaced
energy aloft. A strong low with a non-CMC model blend seemed best
into Sunday. However, later Sunday into Monday, guidance is split
with how the upper low may pivot east or northeast, thus
affecting the surface low track. WPC continuity, earlier model
runs, and GFS runs and many GEFS members take the low more
northeasterly toward Bristol Bay. Meanwhile the 12Z ECMWF came in
much differently, tracking the low east into the Gulf of Alaska,
far south enough to even miss much of Southcentral for
precipitation. This EC-type solution was supported by the EC-AIFS
and many of the EC-based AI/ML models, with the GFS-based
Graphcast also showing some semblance of an eastern track. Thus
attempted to start trending the WPC forecast toward an easterly
track with less emphasis on Bristol Bay and vicinity for the low
movement, using the ECMWF, 00Z EC mean, and the CMC mean seemed
reasonable too. The 12Z EC ensemble members and mean have now also
trended toward this easterly type of low track. Of course it is
also a common pattern for low pressure to filter from Bristol Bay
toward the Gulf of Alaska, so this could be a complicating factor.
After that, models appear to show combining energies coming south
from Siberia and east from the Kamchatka Peninsula to reform an
upper low over the Bering Sea for around Monday-next Wednesday,
and another surface low could accompany. An ECMWF/ensemble mean
blend seemed reasonable for this feature too while awaiting better
model consensus.
...Weather/Hazards Highlights...
A round of moderate to locally heavy precipitation is forecast
for Southeast Alaska into Saturday ahead of the first
upper/surface lows moving through. Some light rain and snow
showers are likely across the Mainland on the backside, with some
minor enhancement in terrain. Meanwhile the Aleutians to the
Alaska Peninsula can expect ample rain and high winds this weekend
with the strong surface low. The track of the low going into next
week will have notable impacts on the sensible weather. With the
low track potentially farther south than the previous forecast,
did trim the northern side of the wind hazard out of the Kuskokwim
Delta. Areas of Southcentral Alaska have a particularly uncertain
forecast dependent on the low track, with not much to very heavy
precipitation all possibilities early next week, though by the
middle of next week precipitation chances may increase with the
next low pressure system. There does look to be moist inflow into
Southeast Alaska with the multiple low pressure systems, so will
continue to monitor for any potential precipitation hazards there.
Temperature-wise, lower elevation areas of the Mainland will
mostly be above average (especially for lows) through the period,
with chillier temperatures in the Brooks and Alaska Ranges.
Southeast should be generally near average in the 40s and low 50s.
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