Alaska Extended Forecast Discussion...UPDATED
National Weather Service College Park MD
528 PM EDT Tue Jul 8 2025

Valid 12Z Sat 12 Jul 2025 - 12Z Wed 16 Jul 2025

...Heat forecast to build across portions of interior and 
northern Alaska this period while it stays wet in the south...


...Synoptic Overview...
In general, upper level troughing persists in the Bering Sea while
ridging waxes and wanes across northern and central AK and ridging
marches eastward across Asia. Undercutting this blocking flow in
the northern stream is a fairly zonal pattern from the Aleutians
into the northeast Pacific/Gulf of AK.


...Guidance Evaluation and Preferences...
Overall, there is reasonable model agreement, but the devil
remains in the details, especially in about a week in the
Aleutians where the GFS/ECMWF bring a fairly strong low nearby. 
Uncertainty with the warm core ridge in AK is seen later on as the
guidance isn't sure what to do with a closed low retrograding
across portions of the Bering -- allow it to become absorbed by
the low to the south or let it retrograde into Siberia, and then
come back towards western AK, which would erode the ridge. 

To deal with the uncertainties in the forecast, an even blend of 
the deterministic 12z runs of the GFS/CMC/ECMWF/UKMET was used 
early on before using up to 40% of the 12z NAEFS/00z ECMWF
ensemble mean solutions later on



...Weather/Hazards Highlights...
A warm core moving into northern and interior AK from north of
Siberia is expected to lead to a period of heat that initially
builds across interior AK from the 11th to the 14th, bringing 
highs into the 80s, but more uncommonly brings 70s and possibly 
80s to the North Slope on the 14th. Uncertainties with the warm
core ridge strength later on keeps a confident answer elusive, but
hazardous heat areas were added to these areas. 

To the south, the series of lows moving into the Gulf will bring
persistent rain chances across southernmost AK, with rain on the
11th in the Panhandle and then another batch of potentially heavy
rainfall on the 14th and 15th -- heavy rain hazards exist across 
southeast AK and the AK Panhandle. With time, as ridging to the 
north erodes, the rainfall footprint and rain chances spread 
northward into central AK and into the Brooks Range, ending the 
interior and northern heat. The 12z Canadian shows heavy rain 
across the eastern interior later on, which will be watched in
case better guidance agreement emerges on this possibility on 
later days.

Roth




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