Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
245 PM EST Tue Dec 11 2018

Valid 12Z Sat Dec 15 2018 - 12Z Wed Dec 19 2018

Ensemble mean solutions from major global models this morning
agree very well that two large scale cyclones will pass south of
the Aleutians and then move toward the south coast of Alaska
during the medium range period.  The first cyclone should approach
southern Alaska Sunday into Monday as it rapidly weakens.  The
second cyclone will quickly follow in its wake and should move
along a similar path into the Gulf of
Alaska by next Wednesday.  Although the deterministic solutions
display the highest degree of uncertainty along the storm track to
the south of the Aleutians, their cyclone center positions are
reasonably clustered through Day 8 next Wednesday.  Therefore, the
WPC Alaskan grid package was derived mainly from the 00Z ECMWF
mean together with the 12Z GEFS mean, mixing in with some of their
deterministic solutions from Days 4 to 6.  In addition, the 00Z
NAEFS was used to derive the temperatures and POPs as well.

Kong


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