Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
646 PM EDT Mon Mar 31 2025

Valid 12Z Fri 04 Apr 2025 - 12Z Tue 08 Apr 2025

***Heavy coastal rain and heavy mountain snow makes a return to
 southern Alaska for Friday into the weekend***

...General Overview...

A generally mild pattern is expected to be in place across most 
of the Alaska domain for the end of the week into the weekend, 
with an upper level ridge axis building northwest into the central
and eastern mainland from western Canada. Meanwhile, a large low 
pressure system organizes over the Gulf and slowly moves towards 
the Alaska Peninsula, and brings a return to heavy coastal rain 
and mountain snow to southern Alaska late Friday and into the 
weekend. Lighter valley rain and mountain snow is expected across
portions of the Interior as the moisture advects inland.

...Guidance/Predictability Assessment...

The 12Z model guidance suite features good overall agreement 
across the Alaska domain for the end of the week with some 
mesoscale differences noted across the Arctic and the North
Pacific, so a CMC/ECMWF/GFS model blend suffices as a starting 
point in the forecast process. The UKMET is faster and to the
north of the model consensus with the Gulf low. The CMC diverges
from the ECMWF/GFS/ensemble means consensus by Day 6 across the
Arctic, so it was reduced by Day 6 and beyond. By next Tuesday, a
broad trough axis tries to become established over the state as
the Arctic trough amplifies more and the weakening low from the
Gulf lifts northward, although the guidance differs on specifics. 
The ensemble means were gradually increased to about half by early
next week, with equal weighting of the ECMWF/GFS/ECENS/GEFS.

...Weather/Hazards Highlights...

Heavy precipitation becomes increasingly likely for the southern 
coastal areas from the Alaska Peninsula to the Prince William 
Sound, and then western portions of the southeast panhandle going
into Friday and the weekend. An expansive area of low pressure 
develops over the central/southern Gulf and slowly lifts north, 
bringing a return to moist and strong onshore flow with coastal 
rain and mountain snow, which will likely be heavy at times and 
potentially anomalous by April standards. This surface low has 
trended steady compared to yesterday's model runs. Gale force 
winds are likely over the open waters of the Gulf, and storm force
gap winds are possible for the eastern Aleutians and portions of 
the Alaska Peninsula on Friday and early Saturday.

Temperatures are generally expected to be above average across the
majority of the state for most of the forecast period, with
readings closer to early April averages across far western
portions of the mainland. It appears the greatest anomalies will
likely be over southeastern portions of the mainland, where
afternoon highs could reach near or just over 50 degrees for some
of the valley locations. A cooling trend likely commences for
early next week as the Arctic trough tries to build back in.

Hamrick


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