Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
241 PM EST Tue Nov 20 2018

Valid 12Z Sat Nov 24 2018 - 12Z Wed Nov 28 2018

...Guidance/Predictability Assessment and Weather
Highlights/Hazards...

Model solutions vary throughout the medium range forecast period
aloft from the Arctic down into the Interior with respect to
shortwave trough digging/separation as well as ridge amplification
from western Canada into eastern Alaska. Accordingly,
collaboration with the NWS forecast offices in Fairbanks and
Anchorage culminated with usage of an ensemble mean forecast
approach to maximize continuity. This solution offers a weak
trough aloft with an axis over northwest Alaska and an amplified
ridge holding into the eastern interior. In this scenario, local
snow potential is limited given moisture and lack of clear focus
in guidance.

Farther south, guidance is well clustered overall with support of
weekend deep storm developments from to the south of the
Aleutians/AKpen to the Gulf of Alaska. Deterministic model
solutions begin differ more in ernest after the weekend these
lows. Accordingly, an ensemble mean forecast approach was utilized
for these features albeit with a need to apply manual adjustments
to insure deep main low pressures consistent with ample dynamic
support aloft. This storm track strongly favors heavy wind/waves
and precipitation for maritime interests along with a threat for
prolonged periods of highly unsettled weather including widespread
heavy precipitation working into southwest/southern and southeast
Alaska.

Schichtel

WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can be found at:

http://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
http://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html