Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
543 PM EST Mon Dec 07 2020
Valid 12Z Fri Dec 11 2020 - 12Z Tue Dec 15 2020
...Guidance and Uncertainty Assessment...
Aside from an agreeable start to the forecast period on Day 4, the
rest of the forecast remains challenging and complicated with
plenty of uncertainty. The basic synoptic pattern is expected to
feature fast zonal flow over the Gulf of Alaska while blocky
ridging over the Chukchi Sea should allow troughing to maintain
itself over the Interior. General storm tracks will favor over the
Aleutians toward Southeast Alaska. The WPC blend this cycle
favored the 12Z ECMWF/CMC deterministic solutions which maintains
a solution consistent with continuity. The 12Z GFS was less
preferred, even excluded by later periods, as it was showing very
fast bias with the storm tracks and synoptic pattern, becoming out
of phase with the other guidance and ensemble means. By day 6-8,
higher components of the ECENS was used.
...Weather/Hazards Highlights...
During Thu-Fri ahead of the strong Aleutians storm and its leading
occluded front, expect an area of strong winds along with focused
precipitation over the eastern Aleutians and possibly southwestern
Alaska Peninsula. The high winds threat will transition across
portions of the central/northern Interior this weekend.
Precipitation should be light and scattered for most of the
Mainland, aside from the coastal areas closer to the storm tracks.
Temperatures are expected to favor below normal to much below
normal, particularly for the central to northern Interior.
Taylor
Hazards:
- High winds across portions of mainland Alaska and the Aleutians,
Thu, Dec 10.
- High winds across portions of mainland Alaska, Sat-Sun, Dec
12-Dec 13.
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