Alaska Extended Forecast Discussion
National Weather Service College Park MD
644 PM EDT Tue Jul 1 2025


Valid 12Z Sat 05 Jul 2025 - 12Z Wed 09 Jul 2025

...General Overview...

An upper high will remain parked over the Arctic and North Slope
through the weekend, resulting in above average temperatures that
will contribute to heightened thunderstorm chances and fire 
weather concerns from the Interior to the North Slope. To the 
South, a few low pressure systems are expected to track east
across the Aleutians into the Gulf, which will result in 
unsettled weather and enhanced precipitation chances for the 
southern coast and Southeast Alaska.


...Guidance Evaluation/Preferences...

Overall, model guidance is in fairly good agreement on the upper
level pattern with some uncertainty in the evolution of individual
upper lows and associated surface features. Ensemble means from 
the GEFS/ECENS/CMCE are in very good agreement through the entire 
period, and the deterministic guidance from the 
GFS/ECMWF/CMC/UKMET are well clustered through the weekend. By 
early next week, the influence from the strong northern ridge 
wanes as the ridge weakens and the evolution of upper lows 
tracking to the south becomes uncertain. All models are in good 
agreement on the low tracks, moving east across the Aleutians and 
into the Gulf, but details such as timing and strength are still 
somewhat unclear. The largest differences appear Monday into 
Tuesday with the main low in the Gulf. The general consensus among
the deterministic and ensemble guidance is to slow/stall the main
low over the Gulf while a secondary low drops into the Gulf 
behind it and ridging builds ahead of it over western Canada. The
12Z GFS diverges significantly from the consensus, pushing energy
from the leading low into Canada and bringing the second low into
the Gulf much faster than expected. As the secondary low 
strengthens in the Gulf late Tuesday into Wednesday, model 
agreement increases again with an expected amount of model spread 
for this time range.

For WPC's forecast blend, a near even blend of the deterministic
GFS/ECMWF/CMC/UKMET was used through the weekend, then ensemble 
means from the GEFS/ECENS/CMCE were added in increasing amounts 
through early next week. Some influence from the deterministic 
guidance was retained Monday-Wednesday, with the ECMWF/CMC making 
up a minority portion of the blend. The GFS was phased out early 
next week as it seems to be an outlier from the general consensus.


...Weather/Hazards Highlights...

The influence of the strong upper ridge over the Arctic and North
Slope will be felt well into the Interior as high temperatures
rise into the 70s and 80s each day through the weekend.
Temperatures will decrease slightly but still remain warm early 
next week as the high weakens. Above average temperatures will
support isolated thunderstorm chances over the Interior, which 
may also lead to heightened fire weather concerns as lightning
could spark new fires amid dry antecedent conditions. 

For southern portions of the state, lows tracking into the Gulf
will result in unsettled weather and daily precipitation chances.
Heavy precipitation is expected to focus over the southern coast,
Kenai Peninsula, and Kodiak Island this weekend, then the focus 
should shift into Southeast Alaska early next week as an upper low
stalls over the Gulf. This pattern is expected to direct a plume 
of moisture at Southeast Alaska, which could result in heavy 
rainfall Tuesday and Wednesday. Chances for light to moderate
precipitation will likely linger along the southern coast through
early next week as well. Forecast precipitation and cloud cover 
should keep temperatures cooler in these areas with daily high 
temperatures in the 50s and 60s. 


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