Alaska Extended Forecast Discussion
National Weather Service College Park MD
750 PM EDT Thu Sep 25 2025
Valid 12Z Mon 29 Sep 2025 - 12Z Fri 03 Oct 2025
...Former Typhoon Neoguri could bring high winds and locally heavy
rain for the Aleutians into the southern Alaska Peninsula Monday
to Tuesday...
...General Overview with Guidance Evaluation/Preferences...
The medium-range period should begin with an occluded cyclone
passing close to the Aleutian Islands early next week. This
cyclone, which has transitioned from a former typhoon named
Neoguri by then, could bring a period of high winds and locally
heavy rain for the Aleutians into the southern Alaska Peninsula
from Monday into Tuesday. The 12Z ECMWF and CMC indicate the most
robust solutions, with the cyclone center brushing just south of
the island chain. The EC-AI runs, however, track the cyclone at a
fair distance away from the Aleutians, a solution supported by
the latest 18Z GFS run. A High Wind area is depicted on the WPC
Day 3-7 Hazards Outlook chart assuming a cyclone track similar to
what the ECMWF and CMC indicate.
Thereafter, the cyclone is forecast to weaken as it slides east
toward the Gulf of Alaska and links up with the remnant
vorticities coming from the Bering Sea low. There is a fair
amount of model spread regarding the timing and placement of the
individual low pressure waves. By late next week, ensemble mean
solutions show decent agreement on a fairly large but modestly
deep cyclone to be centered over the Gulf of Alaska.
Farther north, models show a relatively weak upper-trough
lingering across northern Alaska, with the EC mean keeping this
wave in place well into next week longer than other model
guidance as an omega block emerges over the Arctic Ocean. No
active weather is forecast to associate with this upper trough.
The WPC forecast package for Alaska was based on a consensus blend
of 40% from the 12Z EC/00Z EC mean, 40% from the 12Z GFS/GEFS
mean, and 20% from the 12Z CMC/CMC mean, with the majority of the
blend coming from the ensemble means toward the end of the
forecast period. This blend yielded a solution similar to
yesterday's WPC forecast package except a better-defined cyclone
tracking near the Aleutians for early in the forecast period.
...Weather/Hazards Highlights...
If former Typhoon Neoguri tracks as forecast by the ECMWF and CMC,
the Aleutians into the southern Alaska peninsula can expect a
period of high winds and locally heavy rain from Monday into
Tuesday. Thereafter, some modest amounts of precipitation are
expected to edge into the southwestern and southern coastal areas
and eventually into the Panhandle for the rest of next week. For
the rest of Alaska, other than some snow showers near the western
and eastern ends of the North Slope early next week, benign
weather is forecast to prevail across interior mainland Alaska
into the Brooks Range and North Slope.
In terms of temperatures, colder conditions will be commonplace,
with subfreezing overnight lows widespread across the Interior,
and 10s near the Brooks Range. The greater Anchorage area may have
overnight lows that approach the freezing mark early next week.
Meanwhile, near to slightly above normal temperatures are expected
for all of the southern coastline including the Aleutians and
Panhandle with lows in the 40s and highs in the 50s next week.
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