Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
537 PM EST Thu Dec 08 2022
Valid 12Z Mon Dec 12 2022 - 12Z Fri Dec 16 2022
...Overview...
An upper low/trough across portions of eastern Asia in the
northwest Pacific leads to a broad downstream ridge that, for the
most part, is over Alaska this period. This leads to broad
southwesterly flow across the state, which should act to moderate
interior temperatures for the chill that exists in the short
range. A stormy pattern exists across the Aleutians and portions
of the Bering Sea, while systems occasionally escape the trough to
the west to impact southern Alaska, with a preference for southern
AK to be wet.
...Guidance/Predictability Assessment and Preferences...
The guidance appeared very agreeable after the 00z/06z suite
became available, only to fall apart to some degree once 12z
guidance became available. The WPC preferred blend began with a
general consensus of the ECWMF/CMC/UKMET/GFS to deal with the
detail issues early on (Sunday into Tuesday). The ensemble means
were introduced during Day 5 and steadily increased to about 55%
by the end of the extended period/mid next week. This preference
maintained us much ridging as possible across AK, which early on
the 12z GFS was a champion of, before the Canadian/ECMWF flipped
the script late in the period.
...Weather/Hazards Highlights...
This pattern should lead to increasingly mild/less cold conditions
across the interior as Pacific moisture/cloudiness overwashes the
state. The west and south should be mild as onshore flow persists
more often than not. Storms moving through the western Bering Sea
should bring gale to storm force winds to the Aleutians at times,
with an initial system in the northeast Pacific/Gulf of AK
bringing gales to the south-central and southeast coasts early
next week. The southern part of the state should be quite wet due
to persistent onshore flow.
Roth
Hazards:
- Heavy precipitation across portions of mainland Alaska, Sun, Dec
11 and Thu, Dec 15.
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Mon, Dec 12.
- Heavy precipitation across portions of mainland Alaska and the
Aleutians, Wed, Dec 14.
- Heavy precipitation across portions of the Aleutians, Tue, Dec
13.
- High winds across portions of mainland Alaska, Sun, Dec 11.
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