Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
646 PM EST Tue Dec 07 2021
Valid 12Z Sat Dec 11 2021 - 12Z Wed Dec 15 2021
...Another Major Storm for Alaska...
...Overview and Guidance Evaluation/Preferences and Weather/Hazard
Highlights...
A deep low pressure system over the Bering Sea will track toward
the Southwest Alaska, the Alaska Peninsula/Kodiak Island before
redeveloping into a potent low near the Kenai Peninsula by Friday.
This feature will impact a major of the state by ushering in
strong wind, cold temperatures and/or scattered to widespread
precipitation. Another system is expected follow, tracking over
the eastern Gulf of Alaska over the weekend/early next week; which
will spread the threat of high winds, Gulf waves along with heavy
coastal rains and terrain enhanced heavy snows from south-central
Alaska to the southeast Panhandle. Much below normal temperatures
will be settled in over much of the southern half of the state
after it the system passes. For specifics on the expected hazards,
refer to latest WPC Day 3-7 Hazards Outlook product listed and
linked below.
The global models (GFS, CMC, UKMET and ECWMF) have a decent
clustering with the initial low near the Bering Sea through about
12Z on December 13th before the spread increases. Like the
previous runs, the GFS/ECMWF remain best clustered and in line
with ensembles. There continues to be slowly growing guidance
signal to support additional Bering Sea storm genesis into these
longer time frames, but with an uncertain downstream track and
re-development toward Alaska. To maintain a since of continuity,
the WPC preferred blend had a starting point of the 12Z
GFS/CMC/UKMET/ECWMF/EC ensemble means that trended toward more
inclusion of the EC ensembles and GEFS mean by the later periods.
Campbell
Hazards:
- Heavy precipitation along the Alaska Panhandle to portions of
the south coast of Alaska, Fri, Dec 10.
- High winds across portions of southwestern Alaska and into the
Aleutians, Sat-Sun, Dec 11-Dec 12.
- High winds across central Aleutians, Fri, Dec 10.
- Much below normal temperatures across the southern half of
mainland Alaska and the Alaska Peninsula, Sat-Mon, Dec 11-Dec 13.
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