Alaska Extended Forecast Discussion
National Weather Service College Park MD
704 PM EDT Fri May 30 2025

Valid 12Z Tue 03 Jun 2025 - 12Z Sat 07 Jun 2025


...Heavy rain and strong winds will impact portions of the Alaska
Peninsula and Southwest and Southcentral Alaska into early next 
week...

...Overview...

A consolidated upper low centered over the Bering Sea/eastern 
Aleutians to start the period on Tuesday will be relatively deep 
for early June. This will support a modestly deep surface low into
southwest Alaska Mainland on Tuesday which should weaken fairly 
quickly. Another low will lift northward towards the Gulf into
Wednesday continuing strong onshore flow to fuel moderate to heavy
rainfall across the southern Coast and Panhandle regions, with
some gusty winds. After mid-week, the guidance supports mean
troughing over western Alaska, with ridging building over the
Panhandle and eastern Mainland. Weak shortwaves will rotate south
of the main trough axis, keeping most systems well south of the
Aleutians and conditions over much of Alaska relatively stable.
Another surface low may lift into the Gulf late next week, with
another round of precipitation possible for the Southeast.


...Guidance Evaluation/Preferences...

The latest guidance shows reasonable agreement through much of the
period but plenty of uncertainty in the details of individual
lows. The guidance shows the main low moving quickly into
southwest Alaska the beginning of the period, but there remains
some question on additional energy rotating across the Peninsula
towards the southern Coast, and another weaker surface low lifting
up towards the Gulf. The Canadian and to some extent the UKMET are
on the faster side of the guidance with this low, and the GFS is
strongest, all of which has implications for heavy rainfall 
across the Southeast/Panhandle region. Behind this, later next
week, another surface low looks to lift north towards the
Peninsula/Gulf region, but with much more uncertainty in the
track. WPCs forecast for today used a blend of the deterministic
models the first half of the period, transitioning to half
ensemble means by the second half. 


...Weather/Hazards Highlights...

The ample moisture streaming into parts of southern Alaska in the
form of a weak to moderate atmospheric river will produce areas 
of rainfall that could be heavy across the Alaska Peninsula and 
north toward the Kuskokwim Delta, spreading eastward into the 
favored terrain of Southcentral Alaska early next week. Light to 
moderate precipitation is likely to expand north into the Interior
and perhaps reach the Brooks Range at times. Some higher 
elevation precipitation would be snow in the higher elevations. 
Modest rain is forecast to remain over the southern half of Alaska
as next week continues, while the upper low gradually weakens over
the Mainland. Light rain may reach Southeast Alaska by Monday, 
and moderate to perhaps locally heavy rain could occur in 
Southeast Alaska around midweek depending on the timing of lows.
Gusty winds may accompany these systems as well.

High temperatures near and under the primary upper low are likely
to be cooler than average, covering southern Alaska next week. 
Lows are expected to be closer to average. The Seward Peninsula to
the western and possibly central Interior will be the main area 
of above normal temperatures in the southerly flow just ahead of 
the upper low, especially early next week before moderating. The 
North Slope should also see colder than normal temperatures under 
the influence of an Arctic high.


Santorelli



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