Alaska Extended Forecast Discussion
National Weather Service College Park MD
721 PM EDT Sat May 31 2025

Valid 12Z Wed 04 Jun 2025 - 12Z Sun 08 Jun 2025


...Heavy rain and gusty winds to impact portions of the Southern
Coast and Alaskan Panhandle...

...Overview...

An upper low over the Bering Sea early next week will weaken as it
drifts inland by mid-week. A couple of shortwaves will swing 
south across the Aleutians helping to reinforce troughing over the
western Mainland and sending a couple of weak surface lows towards
the Gulf. This should help maintain a generally unsettled and wet
pattern for southern and southeast Alaska, with moderate to
locally heavy rains in some spots. By late week, ridging may build
across the Gulf and Panhandle but with uncertainty in how strong
it is and how quickly a trough to the west can track towards the
Gulf next weekend. This trough looks like it may send another
surface low towards the Peninsula or southern Coast.


...Guidance Evaluation/Preferences...

The latest guidance shows reasonable agreement through much of 
the period on the large scale pattern, but plenty of uncertainty 
in the details of individual lows. Greater uncercertainty begins
to build late week in regards to how amplified and progressive the
upper pattern becomes. The GFS shows less amplification of a ridge
over the Gulf which allows an upstream trough/shortwave to
progress much quicker than consensus. There seems to be a bit more
agreement for a little bit stronger ridge and a slower or more
northerly track for the shortwave and its associated surface low.
Regardless, there is agreement a surface low will traverse south
of the Aleutians but whether it moves more into the Gulf (GFS) or
the Peninsula/southern Coast (ECMWF and CMC) remains to be seen.
The WPC forecast for today used a blend of the deterministic
models for the first few days of the period, quickly transitioning
to a majority blend of the ensemble means to help mitigate the
greater detail differences later in the period.


...Weather/Hazards Highlights...

Weak surface lows into/towards the Gulf will continue a generally
wet pattern for much of southern and southeast Alaska. An intial
system Wednesday-Thursday will allow for a period of moderate to
locally heavy rains for the Southern Coast and Panhandle. Later
in the week, rainfall intensity should decrease but showers will
continue all along the coastal regions from the Aleutians to the
Panhandle, and even farther inland towards the Brooks range.
Another trough towards the Gulf will increase precipitation again
for parts of the southern Coast and Panhandle but with much more
uncertainty in the amounts and impacts.

High temperatures near and under the initial upper low are likely
to be cooler than average, covering southern Alaska early week.
Temperatures may moderate somewhat behind this trough and ahead of
the next one. The North Slope should also see colder than normal 
temperatures under the influence of an Arctic high.

Santorelli



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