Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
453 PM EST Fri Feb 19 2021
Valid 12Z Tue Feb 23 2021 - 12Z Sat Feb 27 2021
...Overview and Guidance/Uncertainty Assessment...
The 12 UTC ECMWF/UKMET/Canadian models and GEFS/ECMWF ensemble
means solutions offer reasonable continuity and are generally well
clustered Tuesday-Thursday. A composite solution is preferred to
highlight the most predictable weather features. The 12 UTC GFS
seems more of an outlier. Leaned blend emphasis in favor of the
ensemble means days 7/8 consistent with growing model forecast
spread. The WPC medium range product suite was primarily derived
from these WPC blends along with the 19 UTC National Blend of
Models in a pattern with near average forecast
predictability/uncertainty.
...Weather/Hazards Highlights...
Expect much below normal temperatures for much of the Interior
into Southcentral Alaska to persist Monday in a pattern with
lowered heights underneath an Arctic Ocean upper vortex. Heights
rise and temperatures moderate some by midweek with Bering Sea
system approach, but may cool again later week as per a southward
Arctic frontal sag.
Meanwhile, a series of deepening lows in an energetic Pacific
stream will work over the Bering Sea/Aleutians all next week in an
active pattern. The storm track will focus precipitation and
wind/waves to the Aleutians, the AKpen and southwest/western
Alaska as they progress eastward, with energies to track into an
unsettled Gulf of Alaska to support periodic heavier precipitation
into southern and southeast Alaska.
Schichtel
Hazards:
- Much below normal temperatures across portions of mainland
Alaska, Mon, Feb 22.
- Heavy precipitation for parts of the Alaska Panhandle, Mon, Feb
22 and Wed, Feb 24.
- High winds across portions of the Aleutians, Fri, Feb 26.
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