Alaska Extended Forecast Discussion
National Weather Service College Park MD
625 PM EDT Thu May 21 2026

Valid 12Z Mon 25 May 2026 - 12Z Fri 29 May 2026

...High winds and heavy precipitation possible from the
Aleutians through Southcentral Alaska early next week...

...Overview...

Upper level low pressure will build over the eastern Bering Sea
and western Mainland early next week as a Pacific low pressure
system approaches from the southwest. This system is forecast to
track into the Bristol Bay area, creating high wind and heavy
precipitation chances from the Aleutians through southwestern and
Southcentral Alaska. Low pressure will shift into the Gulf of
Alaska mid-to-late next week, which may steer upper level
shortwaves towards Southeast Alaska.


...Guidance Evaluation/Preferences...

Models remain in good agreement on the synoptic scale pattern,
with increasing agreement on the details of the low pressure
system early next week. The ECMWF remains on the slower end of the
guidance envelope, but the spread has narrowed significantly since
yesterday with the general consensus falling slightly faster than
the ECMWF. Impacts are also becoming more clear as we get closer
to the event. 

Uncertainty increases later next week, as is typical at this time
frame. Several weaker shortwaves should pivot around the upper
low/trough shifting into the Gulf of Alaska, and models are
struggling to resolve the timing and evolution of these features.
Shortwaves may focus precipitation chances over Southeast Alaska
and western Canada late next week, but precipitation chances will
ultimately be determined by the position of the shortwaves and any
associated surface features.

A blend of the available deterministic guidance, with a focus on
the GFS and ECMWF, was used as a starting point for the WPC
forecast, and ensemble means from the GEFS and ECENS were added in
increasing amounts Wednesday through Friday to help smooth out
model differences. Influence from the deterministic GFS and ECMWF
was maintained through the end of the period to preserve details
of individual systems.


...Weather/Hazards Highlights...

A strong low pressure system will cross the Aleutians and track
into the Bristol Bay area early next week. The steep pressure
gradient around the system will result in strong, gusty winds from
the Aleutians through southwestern and Southcentral Alaska Sunday
into Monday. Heavy precipitation chances are expected for the
Lower Kuskokwim Mountains and favored terrain areas in
Southcentral Alaska Monday through Wednesday as moisture streams
onshore ahead of the main frontal boundary. Heavy precipitation
may also be possible for upslope terrain on the southern side of
the Alaska Peninsula.

Low pressure will linger over the eastern Bering Sea and western
Mainland as the system weakens mid-week, then low pressure is
expected to shift into the Gulf of Alaska. This pattern will
prolong unsettled conditions for the southern half of the state
and could focus enhanced precipitation chances over Southeast
Alaska late next week.

Temperatures are forecast to remain below average for the
southern half of the state due to could cover and precipitation
and for the North Slope under the influence of high pressure to
the north. Temperatures will likely rise above average for
much of Interior Alaska where daily high temperatures are
forecast to reach the 50s and low 60s. Warm temperatures should
support scattered showers and isolated thunderstorms across the
Interior next week, which could increase chances of lightning
strikes starting wildfires.


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