Alaska Extended Forecast Discussion
National Weather Service College Park MD
620 PM EDT Wed Jun 4 2025


Valid 12Z Sun 08 Jun 2025 - 12Z Thu 12 Jun 2025


...Another Gulf of Alaska storm to bring a heavy rainfall threat 
and winds to Southcentral and Southeast Alaska this weekend...


...Guidance Evaluation/Preferences...

The WPC Alaskan medium range guidance suite was mainly derived 
from a composite blend of well clustered guidance of the 12 UTC 
GFS/ECMWF/UKMET/Canadian models valid for Sunday and Monday. This 
solution has good ensemble and machine learning guidance support 
and maintains good product continuity in an active pattern with 
above average predictability. Guidance offers reasonably similar 
larger scale flow evolutions into next week, but model forecast 
spread and uncertainty grows more rapidly with smaller scale 
system depictions. Accordingly, prefer to pivot to a composite of 
better clustered guidance of the 12 UTC GEFS/ECMWF/Canadian
ensemble means for these longer time frames in overall more 
benign flow over the state. In this blend, applied greater 
weighting to the ECMWF ensemble mean that generally seems best in
line with more common multi-model details. 

...Weather/Hazards Highlights...

A concentrated area of heavier rainfall is expected along the 
southern coast and into the Southeast this weekend as another 
upper-low/accompanying surface frontal system lifts from the 
northeastern Pacific into the Gulf bringing a fetch of Pacific 
moisture. This collaborated threat is depicted on the WPC Hazards
Outlook. Some quite gusty winds are also expected, particularly 
for favorable gap locations around the main low. 

Meanwhile, expect scattered precipitation chances will continue 
Sunday into Monday down mainly across the west-central mainland 
as focused locally by a slowly southward shifting upper low. This 
low will gradually work from the northern to eastern Gulf of 
Alaska next week to support a moderately unsettled and rainy 
pattern from coastal Southcentral to the Southeast in replacement
of the much wetter/windy lead southern stream Gulf of Alaska low.

Upstream, high latitude system translations have less than stellar
run to run guidance continuity, but offer a pattern for some 
increased precipitation chances to northwestern areas of the 
state next week as moisture is channeled around a building ridge
into Southwest/West Alaska in the wake of the exiting weekend
Interior upper low. Also, a series of uncertain Pacific systems 
slated to work into the Bering Sea and Aleutians will likely 
bring some enhanced rainfall chances in unsettled flow, with depth
and detail emerging into shorter time frames to monitor.

Schichtel



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