Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
758 PM EDT Wed Apr 16 2025

Valid 12Z Sun 20 Apr 2025 - 12Z Thu 24 Apr 2025

...General Overview...

The next organized storm system develops over the central/western
Aleutians on Sunday and will likely track in the general 
direction of the Alaska Peninsula come Tuesday morning, bringing 
more rain/mountain snow and gusty winds. Ahead of this storm will 
likely be a building ridge axis from the Gulf to the Interior, 
while a strong Arctic surface high and polar easterlies continue
from the Brooks Range northward. An upper trough is likely to
become established over the Gulf by the middle of next week.

...Guidance/Predictability Assessment...

The 12Z model guidance suite, along with the 18Z GFS, are in good
synoptic scale agreement across the Alaska domain for the upcoming
weekend. By Monday, the GFS becomes faster with the Bering Sea
storm system, and this continues to be the case going forward to
Monday/Tuesday, and then north of the model consensus by mid-week
as the system emerges over the Gulf, so less GFS was used for the
latter half of the forecast period. Model and ensemble spread is
higher than normal across the North Pacific and Gulf for Wednesday
and Thursday, with multiple adjustments to the forecast expected
in the days ahead. The WPC forecast transitioned to about half
ensemble means by midweek.

...Weather/Hazards Highlights...

Attention turns to the Aleutians storm by Sunday and into early
next week with southerly flow advecting moisture towards the 
terrain of the Alaska Peninsula, and eventually Kodiak Island and 
the Kenai Peninsula. This does not appear to meet hazardous level
criteria for now, but this will continue to be monitored in the 
days ahead. Temperatures are expected to be near to above average 
across central and southern portions of the mainland, and below 
average across the Brooks Range and to the Arctic Coast where the
Arctic high will have more of an influence on the weather. There
will likely be strong polar easterlies in place across northern
Alaska, and even though winds are not expected to reach hazardous
criteria, periods of blowing snow are possible.

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