Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
644 PM EDT Sun Apr 27 2025

Valid 12Z Thu 01 May 2025 - 12Z Mon 05 May 2025

...General Overview...

The first days of May are expected to be rather unsettled in terms
of expected weather conditions from the Alaska Peninsula to the
southeast Panhandle, courtesy of multiple low pressure systems 
and moist onshore flow from the Gulf. Aloft, a broad upper low is
expected to be in place across the Bering for the middle to end of
the week, and then pivoting to the Gulf by next weekend and next
Monday. Meanwhile, the Arctic surface high will continue to be
strong and result in sustained polar easterlies north of the
Brooks Range, and continued below average temperatures in many
cases.


...Guidance/Predictability Assessment...

The 12Z model guidance suite features good overall model agreement
for the middle to end of the week, and therefore a deterministic 
model blend suffices as a good starting point in the forecast 
process. Looking ahead to next weekend, timing differences become
more apparent across the North Pacific, especially with the 
second system approaching the Gulf region. There has been a
northward trend in the guidance with that low compared to 
yesterday by roughly 100 miles or so. Similar to yesterday, the 
CMC remains slower than the model consensus with the arrival of 
that weekend system, and therefore more weighting was applied to 
the ECMWF/GFS and their ensemble means for Sunday into Monday.


...Weather/Hazards Highlights...

Late season heavy rainfall is still expected from eastern portions
of the Alaska Peninsula to the Prince William Sound region for 
the middle of the week. An atmospheric river is likely east of a 
northern Gulf low Wednesday into Thursday morning, with 2-4 inches
of liquid equivalent for the south facing terrain. Although there
should be some abatement in precipitation intensity going into the
end of the week, it will unfortunately remain unsettled for the
southern coastal areas with damp onshore flow continuing and
periods of rain and mountain snow. Depending on what the next 
system does next weekend, there will likely be a return of 
additional rainfall for the southern coastal areas and extending
to the southeast Panhandle. 

A quasi-stationary frontal boundary draped across the Interior for
most of the forecast period will separate a mild and spring-like
airmass across south-central Alaska, from a much colder and
polar-like airmass from the Brooks Range northward. Temperatures
are generally expected to be below average with the Arctic surface
high continuing to govern the overall weather pattern.


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