Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
707 PM EDT Fri Mar 21 2025

Valid 12Z Tue 25 Mar 2025 - 12Z Sat 29 Mar 2025

...Overview...

A broad upper low/trough is expected to encompass most of the Gulf
region for the middle of the week, with a weakening surface low
south of the Kenai Peninsula and a forming low over the eastern
Gulf that will become dominant. This low should lift north and
then northwestward into Friday and Saturday over the northern Gulf
as a blocky upper level pattern becomes established. Meanwhile, an
upper ridge becomes amplified over the Aleutians and over the
southern Bering Sea going into the end of the week, with some
potential shortwave energy crossing the Bering Sea north of the
ridge axis.

...Guidance/Predictability Assessment...

The ensemble means are overall in agreement on the large scale
synoptic pattern across the domain in how the upper low evolves
across the Gulf and the downstream upper ridge across the
Aleutians and Bering Sea. However, the deterministic guidance
disagrees on how shortwaves from eastern Siberia cross the
northern periphery of the Aleutians ridge. The CMC and UKMET favor
a stronger shortwave reaching Bristol Bay and the southwestern
mainland around Thursday. In addition, the GFS becomes much
stronger with a closed upper low crossing the Bering and reaching
the western mainland around Friday, but its ensemble mean is not
on board with this scenario, so it was tapered down in the
forecast blend beyond Thursday. This also holds true for the UKMET
and CMC solutions by Wednesday. Given the deterministic spread by
next Saturday, the ensemble means accounted for about 2/3rds of
the model blend by that time. 


...Weather/Hazards Highlights...

The southern coast and Panhandle will likely see periods of 
mainly light to moderate coastal rain and mountain snow on 
Tuesday in association with gradually weakening low pressure 
settling over the southern Gulf. A weakening front could provide
precipitation to the Aleutians on Tuesday. Much of Alaska should 
be dry for midweek, but by late week, surface low re-development
over the northern Gulf will likely result in additional rain and
mountain snow for Southeast Alaska, though the details are yet to
be determined.

Expect temperatures to gradually moderate closer to normal by 
Tuesday and into Wednesday as the upper trough weakens. The North
Slope and Brooks Range should be near average through much of 
next week, while the Interior and the Panhandle could see a mix of
above and below normal temperatures.

Hamrick


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