Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
406 PM EDT Fri Aug 24 2018

Valid 12Z Tue Aug 28 2018 - 12Z Sat Sep 01 2018

Model guidance this morning continues to support a deep-level
blocking high anchoring over the Northeast Pacific as a couple of
typhoons undergoing extratropical transition near Japan and Korea
are forecast to merge and move into the Bering Sea and western
Alaska during the latter half of next week.  The 00Z EC mean and
06Z GEFS seem to agree reasonably well with this overall synoptic
pattern evolution through the end of next week.  The 12Z GFS shows
a slower northeastward motion of the merger cyclone across the
Bering Sea next Wednesday than what the 00Z EC mean/06Z GEFS
shows.  Therefore, the 12Z GFS has not been included for the
longer range model blend.  The 00Z ECMWF is included for the early
part of the forecast period but is progressively taken out of
consideration toward the 00Z EC mean/06Z GEFS blend through Day 8
next Saturday.  This yields a slightly faster eastward progression
of the weakening cyclone across Alaska late next week compared
with yesterday's WPC progs.  For the temperature and POP grids,
the 12Z ECMWF has been included along with the 00Z EC ensemble
mean, 00Z NAEFS, and some of the 12Z GFS and 12Z GEFS.

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