Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
425 PM EST Thu Feb 11 2021
Valid 12Z Mon Feb 15 2021 - 12Z Fri Feb 19 2021
...Guidance/Uncertainty and Weather/Hazards Assessments...
An active, stormy pattern is expected across southern portions of
the region as a series of low pressure systems track from the
Bering Sea across the Gulf and southern Mainland within the broad
upper level trough. 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.
These deep lows tracking from the Bering to the western Gulf of
Alaska may be impactful to the Aleutians, southwest Alaska and
nearby Alaska Peninsula and Kodiak as the flow wraps around. 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.
Overall the deterministic models and their respective ensemble
means are fairly clustered and in mutual agreement with multiple
systems passing through the Bering Sea. A combination of the 12Z
GFS/ECMWF/CMC and GEFS/ECMWF ensemble means provided a decent
forecast for the extended periods. The weighting of the ensemble
means were increased for days 7 and 8 where the spread over the
eastern Gulf was more pronounced.
Campbell
Hazards:
- Much below normal temperatures across portions of the Alaska
Panhandle, Sun, Feb 14.
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