Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
424 PM EDT Wed Aug 22 2018

Valid 12Z Sun Aug 26 2018 - 12Z Thu Aug 30 2018

...Guidance/Predictability Assessment and Weather Threats...

Models and ensembles continue to indicate that a blocking high
will become anchored over the Northeast Pacific as a broad
positively-tilted trough with numerous mid-latitude disturbances
are forecast to converge over the Bering Sea during the medium
range period.  It appears that the Aleutians northeastward into
western Alaska will be under an active storm track into next week
while southern and southeastern Alaska will be under the
protective influence of the blocking high to the south. 
Meanwhile, the extratropical merger of Typhoons Soulik and Cimaron
from the western Pacific could intensify as it heads toward the
Bering Sea during midweek next week, and possibly approaching the
west coast of Alaska by next Thursday.

Due to a severe network outage here at WPC from yesterday through
this morning, none of the 00Z guidance were available to us to
compose the Alaskan grids.  Nevertheless, we were able to make use
of the 06Z and 12Z GFS together with the 12Z GEFS to derive the
sea-level pressure field through Day 8 next Thursday.  The derived
synoptic patterns showed good agreement with what the 12Z ECMWF
showed (which arrived afterward).  For the temperature and POP
fields, a combination of the 06Z and 12Z GFS, the 12Z ECMWF, the
12Z GEFS mean, and the 15Z NBM were used.

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