Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
516 PM EST Sun Nov 15 2020
Valid 12Z Thu Nov 19 2020 - 12Z Mon Nov 23 2020
...Stormy Pattern 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 quite compatible 12 UTC
GFS/ECMWF/Canadian, 12 UTC GEFS/ECMWF ensemble means and 19 UTC
National Blend of Models days 4/5 (Thu/Fri) in a pattern with
above average system predictability. Opted for a still compatible
ensemble mean and National Blend of Models composite blend days
6-8 amid growing forecast uncertainty, but again manually adjusted
offshore lows deeper consistent with favorable upper support and
model trends.
...Weather/Threats Highlights...
Upper ridging over the Interior/North Slope will moderate
temperatures significantly mid-later week in a mainly benign
pattern. Meanwhile, cooling lead upper troughing lingering
underneath over the far eastern Gulf of Alaska and Southeast
Panhandle will slowly lose influence over the area Thursday.
Upstream, there remains a strong guidance signal supporting
amplified upper trough/closed low developments into the Bering Sea
and Aleutians mid-later week, then again next Sun/Mon. These will
offer several significant threats for deep offshore storms to
focus enhanced winds/waves and precipitation across the region.
Downstream energy transfer later week through early next week will
also increasingly threaten southwest Alaska, southern Alaska, then
southeast Alaska as ample upper trough/deepened storm energies
work more in earnest across 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