Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
624 PM EDT Sat May 29 2021
Valid 12Z Wed Jun 02 2021 - 12Z Sun Jun 06 2021
...Overview and Guidance Evaluation...
The weather pattern for the medium range period will be featured
with a trio of upper lows across the region on Wednesday, with an
arctic low drifting southward near Nome, and the other two lows
across the north Pacific and the Gulf region. There may be a bit
of a Fujiwara effect as these lows pivot around each other through
the end of the week. By next weekend, the pattern looks to become
less active across the southern portions of the state as an upper
level ridge attempts to build in across the Gulf.
In terms of the models, there appears to be decent deterministic
agreement through Thursday night, mainly owing to the amplified
pattern in place. The 12Z GFS becomes more progressive and
stronger with the main upper low crossing the Aleutians and
northern Gulf region, whilst the ECMWF is considerably slower,
with the CMC between the two solutions. By next weekend, there is
good agreement that the arctic low will linger over far eastern
Siberia, while differences are more substantial across the north
Pacific. The WPC forecast was primarily derived from a blend of
the 12Z ECMWF/GFS/CMC through Thursday, and then a slight increase
in the ensemble means for Thursday through Saturday with less of
the operational GFS.
...Weather/Threats Highlights...
The persistent low pressure and onshore flow from the Alaska
Peninsula to the southeast panhandle region through the end of the
week is expected to produce multiple rounds of moderate rainfall
for coastal areas and nearby mountain ranges. Some locations
could receive an inch of rainfall through Thursday, especially
across topographically favored areas, followed by lighter rain and
some drier periods by the end of the week and into the weekend.
Some showers can also be expected across portions of the Interior,
mainly for the middle of the week. Temperatures are expected to
reach the 60s across much of the Interior for highs, and remaining
quite chilly north of the Brooks range where highs should remain
in the 30s and 40s.
Hamrick
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards 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