Alaska Extended Forecast Discussion
National Weather Service College Park MD
704 PM EDT Mon Jun 2 2025

Valid 12Z Fri 06 Jun 2025 - 12Z Tue 10 Jun 2025

...Overview...

The extended range period starts Friday with a weakening upper-
low over mainland Alaska that will linger into the weekend. To 
the South, an upper-level low and accompanying surface frontal
system will lift northeastward from the northeastern Pacific and
into the Gulf of Alaska. Both lingering precipitation chances from
the initial upper-low and the approach of the next system will
keep unsettled weather in the forecast at least through the
weekend, with a general downward trend in precipitation as the
Gulf system begins to weaken early next week. The presence of the
initial upper-low and quick approach of the next upper-low will
keep mean troughing in place and a period of generally below 
average temperatures for the state. 


...Guidance Evaluation/Preferences...

Most of the guidance remains in generally good agreement on the
overall synoptic pattern late this week, through the weekend, and
even into early next week. All models show an upper-low lingering
over the mainland following a Gulf system and period of heavy 
rainfall, particularly along the southern coast, during the middle
of this week. Models then show another upper-low/accompanying
surface frontal system over the northeastern Pacific lifting
northeastward into the Gulf of Alaska during the Friday-Saturday
timeframe. Thereafter, the latest runs of the GFS diverge compared
to both the ECMWF/CMC as well as the ensemble means, bringing the
upper-low northeastward and inland over southeastern portions of
the state/northwestern Canada faster as it transitions into an 
open wave, with the system at the surface weakening faster over
the Gulf as a result. The rest of the guidance, including the
ECMWF/CMC as well as the ensemble means, shows a slower
progression and the weakening system remaining in the Gulf longer
into Sunday/Monday. Then, all guidance besides the GFS shows a 
broadening area of higher pressures over the northeastern 
Pacific/Gulf, extending northwestward over the Aleutians, while 
the GFS depicts a weak upstream system moving into the Bering Sea.
The other guidance does indicate another system upstream may 
approach the Bering Sea/Aleutians, helping to break down the 
ridging, but likely later into the middle of next week beyond the 
current forecast period. The updated WPC forecast follows a 
similar guidance blend as the prior forecast based on this 
consistent pattern, initially using a composite blend of the 
GFS/ECMWF/CMC before favoring the ECMWF/CMC and an increasing 
contribution from the ECens/CMC ensemble means later in the 
period. The most notable trend in the updated forecast is a 
slightly faster and stronger depiction of the Gulf system this 
weekend, which will need to be monitored for potential associated 
impacts. 


...Weather/Hazards Highlights...

Precipitation chances will continue into the weekend and next 
week broadly across the mainland as a lingering upper-low remains 
in place, possibly reinforced by additional energies from the 
Arctic and incoming from the northeastern Pacific. Showers and 
possible thunderstorms will be most likely/widespread Friday 
before diminishing in coverage and intensity in the following 
days. A more concentrated area of heavier rainfall is likely along
the southern coast and into the Southeast this weekend as another
upper-low/accompanying surface frontal system lifts northeastward
from the northeastern Pacific and into the Gulf bringing another 
fetch of Pacific moisture. At least a couple inches of rainfall 
will be possible, possibly higher, especially from Cordova 
southeast past Yakutat and into northern portions of the 
Southeast. Shower chances may linger into early next week as the 
system weakens but with much lighter amounts of rainfall expected.
Some lighter showers will also be possible on the backside of the
system along the Alaska Peninsula and portions of the Aleutians. 

High temperatures across much of the state will remain below
average through the weekend and into early next week as mean 
troughing remains in place in the upper levels. Most of the state 
will see highs 5-15 degrees below average, with even greater 
anomalies along the North Slope of 15-25 degrees. Forecast high 
temperatures are generally in the 30s for the North Slope, 40s and
50s for western interior/coast and Aleutians, 50s for the 
Southeast, and 50s to low 60s for the central/eastern interior and
Southcentral. While temperatures will remain cooler and below 
average, there does look to be a slow but steady warm up through 
the period, with temperatures rising a degree or two each day. 

Putnam



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