Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
413 PM EST Thu Nov 12 2020
Valid 12Z Mon Nov 16 2020 - 12Z Fri Nov 20 2020
...Guidance/Predictability Assessment...
The WPC Alaskan medium range product suite was primarily derived
from a blend of the 12 UTC GEFS/ECMWF ensemble means and the 19
UTC National Blend of Models days 4-8. Opted for only a quite
limited inclusion of deterministic model guidance due to smaller
scale system and phasing variance that is evident earlier than
normal by the start of this forecast period. WPC continuity was
well maintained with this forecast strategy.
...Weather/Threats Highlights...
Above normal temperature should persist over the North Slope for
the next week and western Alaska under upper ridging, but expect a
cooling trend that will lead to below to much below normal
temperatures for much of the rest of the mainland into early next
week as an amplified upper trough works from the Interior to the
Gulf of Alaska. The upper trough favors unsettled conditions,
especially for the Southeast Panhandle. Cooled temperatures and
unsettled flow then overall moderates as support weakens/heights
rise.
Upstream, systems traversing the Bering Sea/Aleutians early next
week will gradually weaken into the lead/amplified upper ridge,
but still present unsettled maritime conditions and some onshore
precipitation into western/northwestern Alaska. There is then an
increasing guidance signal supporting additional upper
trough/closed low development and approach into the Bering Sea and
Aleutians through mid-later next week that would bring a threat
for periods of enhanced winds/waves and precipitation across the
region, then increasingly with time into portions of western and
southwestern/southern 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
Hazards:
- Much below normal temperatures across portions of mainland
Alaska, Sun-Mon, Nov 15-Nov 16.
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