Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
247 PM EDT Wed Oct 10 2018

Valid 12Z Sun Oct 14 2018 - 12Z Thu Oct 18 2018

...Weather Highlights/Hazards...

An amplified mid-upper level ridge will build from southeast
Alaska to over the interior/North Slope next week downstream from
a deep Aleutians to Alaska peninsula/southern Bering Sea closed
trough/low. This powerful storm remains well depicted in guidance
is slated to deepen and track near the Aleutians and AK peninsula
Sun/Mon before lifting to Bristol Bay then southwest/western
Alaska by next midweek on the western perphery of the blocking
downstream ridge. This is expected to offer a significant maritime
high winds/seas hazard and a heavy precipitation threat from the
Aleutians/AK peninsula and southwest/western Alaska onward to
southern Alaska consistent with a protracted period with deep
layered moisture inflow. Locally disruptive snow/ice is likely
where cold enough in terrain and the interior despite more modest
precipitation potential.

...Guidance and Predictability Assessment...

Well clustered model and ensemble forecasts suggest above normal
forecast confidence over the next week. Accordingly, the WPC
Alaskan medium range product suite was primarily derived from a
composite blend of the latest GFS/GEFS mean and ECMWF/ECMWF
ensemble mean, leaning blend weighting in favor of ensemble means
days 6/7 consistent with slowly growing forecast spread. This WFO
collaborated solution maintains good WPC continuity.

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