Alaska Extended Forecast Discussion
National Weather Service College Park MD
737 PM EDT Wed May 21 2025
Valid 12Z Sun 25 May 2025 - 12Z Thu 29 May 2025
...General Overview...
The southern portions of Alaska will continue to remain rather
unsettled given the time of year with periods of rainfall likely
each day from the Kenai Peninsula eastward to the southeast
Panhandle region. A weakening low pressure system on Sunday will
give way to an incoming low from the Bering that will set up over
the central Gulf through the middle of next week, with moist
onshore flow. Meanwhile, an arctic trough will brush by the
northern third of the state through Monday and a weak upper ridge
axis across the Interior, where scattered showers and
thunderstorms are likely.
...Guidance Evaluation and Preferences...
The 12Z model guidance suite features better overall agreement
across the Alaska domain for the upcoming weekend when compared
to yesterday's guidance at similar time scales. The UKMET was a
bit slower with the Bering low when compared to the model
consensus, so it was weighted less in the model preference.
Additionally, the 12Z GEFS mean was also to the model consensus
through Tuesday, so this was favored slightly more than the slower
ECENS. The guidance has also come into better agreement on a
reinforcing trough/shortwave behind it, which will maintain the
low over the Gulf longer. The ensemble means were increased to
about half by next Thursday.
...Weather/Hazards Highlights...
Periods of rain and high mountain snow are expected from the
Alaska/Kenai Peninsulas to the southeast Panhandle region, with
the greatest coverage and intensity expected from Juneau and
points south. A heavy rain area remains depicted in the WPC
medium range hazards graphic for the 24th to the 28th given how
late in the season this is, and the duration of the rainfall
expected, even though it will not be as heavy as many early season
events. Farther inland across the Interior, scattered afternoon
and evening thunderstorms are likely to develop in the presence of
an unstable airmass, and lightning strikes from these storms may
increase the threat of wildfires in the region.
Temperatures overall are expected to be near to slightly above
average by late May standards across the central and southern
mainland, and slightly below north of the Brooks Range. Cooler
conditions are also likely for the coastal areas and the near
shore islands owing to increased cloud cover and rainfall.
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