Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
356 PM EST Sat Nov 14 2020
Valid 12Z Wed Nov 18 2020 - 12Z Sun Nov 22 2020
...Stormy Pattern next week for the Bering Sea and Gulf of
Alaska...
...Guidance/Predictability Assessment...
The WPC Alaskan medium range product suite was primarily derived
from a composite blend of the compatible 12 UTC GFS/ECMWF, 12 UTC
GEFS/ECMWF ensemble means and 19 UTC National Blend of Models days
4-8 in a pattern with average to above average system
predictability. Inclusion in the composite of the ensemble means
was intended to mitigate some model detail consistent with
uncertainty, but then manually adjusted offshore lows deeper
consistent with favorable upper support and model trends.
...Weather/Threats Highlights...
Short range transition of an amplified upper ridge from the Bering
Sea to over the Interior will moderate temperatures there
significantly next midweek and foster a mainly benign pattern over
the region as precipitation focusing upper trough energy lifts on
the western periphery of this ridge over western/northwestern
Alaska. Meanwhile, lead upper troughing held underneath over an
unsettled eastern Gulf of Alaska and Southeast Panhandle will
slowly weaken and lose influence over the area into Thursday.
Upstream, there is now a strong guidance signal supporting
amplified upper trough/closed low developments into the Bering Sea
and Aleutians mid-later next week. These will offer several
significant threats for deep offshore storms to focus enhanced
winds/waves and precipitation across the region, then increasingly
later next week/weekend into southwest Alaska, southern Alaska and
then eventually southeast Alaska as ample upper trough/deepened
storm energies work more in earnest into the Gulf of Alaska.
Schichtel
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