Alaska Extended Forecast Discussion
National Weather Service College Park MD
742 PM EDT Fri Jun 27 2025


Valid 12Z Tue 1 Jul 2025 - 12Z Sat 5 Jul 2025

...General Overview...

The main theme of the overall weather pattern expected for the
first five days of July will be a broad upper low/trough that 
will be situated over the northern Gulf, and an upper ridge axis 
that evolves into a closed upper high over the western mainland 
towards the end of the week. With an incoming upper low from the 
western Bering, this will tend to form an omega block pattern that
will likely have some staying power from the middle of the week 
and beyond. Warm conditions continue across the mainland with 
scattered showers and storms for portions of Interior, and 
periods of light rain for the southern coastal areas.

...Guidance Evaluation/Preferences...

The 12Z model guidance suite is in good agreement with the low
over the northeastern Gulf, but struggles with incoming shortwave
energy from the Bering Sea that affects western mainland Alaska
and the Aleutians that is ahead of the larger upper low that
follows later in the week. This shortwave energy will tend to 
reinforce the upper low that will already be in place across the 
northern Gulf. Speaking of the next low entering the Bering late
in the week, the GFS seems to differ the most from the consensus
by being displaced well to the southwest, and this continues going
into next Saturday, so it was weighted less in the forecast blend
beyond Wednesday. The ensemble means were gradually increased to 
about half by next Friday.

...Weather/Hazards Highlights...

A broad upper level low with reinforcing surface lows will be
present across the northern Gulf through most of the forecast
period. The upper ridge axis appears likely to build back in to
the north across the central and northern mainland going into the
middle of next week and potentially forming an omega block type 
pattern as a closed upper high likely develops. Meanwhile, a 
trough approaches from eastern Siberia for the middle to end of
the week, but does not appear to be all that impactful for now.

There will likely be an increase in shower and thunderstorm 
coverage going into early next week across eastern portions of 
the Interior. Relatively moist northeasterly flow approaching the 
central and eastern portions of the Alaska Range will increase the
potential for heavier rainfall, with the highest totals where 
there is an upslope flow component where up to an inch of rainfall
will be possible. This rainfall would help to mitigate any 
ongoing fire weather concerns. Showers are also expected for 
southeast Alaska as moist onshore flow continues courtesy of the 
loitering low over the northern Gulf.

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