Alaska Extended Forecast Discussion
National Weather Service College Park MD
636 PM EDT Mon Oct 20 2025
Valid 12Z Fri 24 Oct 2025 - 12Z Tue 28 Oct 2025
...Heavy rain and gusty winds likely for the Southeast this week...
...Overview...
An upper low will drift slowly south across the Bering while
multiple waves rotate around it. The low is forecast to elongate
early next week as it shifts from over the Bering to the Gulf of
Alaska. Another upper low is expected to linger over the Gulf
through the weekend. This upper level pattern will produce several
surface low pressure systems that will track across the Aleutians
and into the Gulf, resulting in generally unsettled weather for
southern Alaska, especially the Aleutians and Southeast Alaska.
Southeast Alaska may see heavy rain and gusty winds as a
relatively stronger low pressure systems approaches mid-to-late
this week.
...Guidance Evaluation/Preferences...
Model guidance continues to show relatively good agreement on the
overall large scale pattern, with some expected uncertainty in
the details. The highest uncertainty will surround the evolution
of low pressure moving from the Bering to the Gulf early next
week. Previous model runs were showing some interaction with an
Arctic low, but the 12Z model suite has backed off from that idea,
resulting in a cleaner consolidation of low pressure in the
Bering this weekend. As the low gradually shifts south towards the
Gulf early next week, the evolution becomes a bit messier with
several shortwave interactions that are harder for models to
resolve. For now, a blend of the best clustered deterministic
models (12Z GFS and ECMWF) and ensemble means from the GEFS and
ECENS produced a decent forecast that represents the pattern well.
WPC's forecast used a blend of the latest runs of the available
deterministic models (GFS/ECMWF/CMC/UKMET) for Friday and
Saturday, added ensemble means from the GEFS and ECENS (20% of
blend) on Sunday, and used a mix of the deterministic GFS and
ECMWF (60% of blend) and ensemble means from the GEFS and ECENS
(40% of blend) for Monday and Tuesday. This maintained good
consistency with yesterday's forecast and represents the pattern
well, smoothing out model differences while maintaining some
detail through the end of the period.
...Weather/Hazards Highlights...
Another round of heavy precipitation (with mountain snow) is
forecast for Southeast Alaska mid-to-late this week as a low
pressure system approaches from the Gulf. This system should be
pretty quick, producing a period of heavy precipitation Wednesday
into Thursday, then moving swiftly into Canada. Strong, gusty
winds will likely accompany this system on Thursday. The heaviest
winds (and consequently waves) will be offshore though, but this
will create a significant maritime threat. Some moderate gap winds
may be present in favorable locations on the backside of this low
as well.
Precipitation chances may linger over southern and Southeast
Alaska through the weekend and into Monday as low pressure lingers
over the northern Gulf with troughing extending along the coast.
Generally unsettled weather can be expected, but nothing
particularly hazardous is forecast. Precipitation chances should
decrease on Tuesday as high pressure nudges towards the region
from the northwest, steering an approaching Pacific low to the
south of the state.
Meanwhile, low pressure in the Bering is forecast to slowly move
south late this week into the weekend. Winds and precipitation
associated with this low should remain over the open waters of the
Bering, then move over the Aleutians late this weekend. Little to
no impacts are expected for western Alaska from this system. This
low will spawn several fronts that will pivot around it while it
is over the Bering, then one dominant frontal system will emerge
across the Aleutians into the Gulf early next week.
Quiet weather is expected for northern and interior Alaska with
relatively higher pressure forecast to develop over these regions
this weekend into early next week. High pressure combined with
generally southerly flow will result in above normal temperatures
through the period.
Dolan
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