Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
531 PM EST Fri Feb 12 2021
Valid 12Z Tue Feb 16 2021 - 12Z Sat Feb 20 2021
...Guidance/Uncertainty and Weather/Hazards Assessments...
The latest model guidance is fairly clustered and in general
agreement with the evolution of multiple storm systems passing
through the Bering and Gulf of Alaska within the upper-level
trough. This will keep much of the islands, peninsulas,
southwest/southern Mainland along with parts of the Panhandle
stormy through the next week. Each storm system will usher in
stronger wind gusts and precipitation mainly near the coasts
nearby inland areas. Meanwhile, the North Slope and areas into the
Interior will mainly be cold and dry as impulses traverse through
the upper ridge. Below normal temperatures across the Panhandle
initially with moderate by early next week. Due to model spread
increasing by mid/late periods over the eastern Gulf of Alaska,
there is uncertainty as to whether organized precipitation will
affect southern Mainland and the Southeast.
A combination of the 12Z GFS/ECMWF/CMC and the respective ensemble
means provided a decent forecast for the extended periods. The
weighting of the ensemble means were increased gradually to the
end of extended, where the spread over the eastern Gulf was more
pronounced.
Campbell
Hazards:
- Heavy precipitation across portions of mainland Alaska, Wed-Thu,
Feb 17-Feb 18.
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