Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
233 PM EDT Wed Aug 01 2018

Valid 12Z Sun Aug 05 2018 - 12Z Thu Aug 09 2018

Medium range period will be driven by a strong upper high south of
the central Aleutians that flattens late on Monday.  An upper
trough between Eastern Siberia and northern AK is expected to
consolidate with time.  The models/ensembles were in good
agreement on the pattern evolution, including many of the details.
 The 500 hPa heights, wind grids, and pressures were based on a
blend of the 00z UKMET, 00z Canadian, 06z GFS, and 00z ECMWF for
Saturday night into Sunday night before using increasing amounts
of the 00z ECMWF ensemble mean and 00z NAEFS mean thereafter,
eventually becoming 50% of the blend.  The remainder of the grids
were half deterministic (including the 12z GFS) and half ensemble
mean through the period to account for the usually greater
temperature and precipitation chance uncertainty.

Pattern will be rather wet for the panhandle near and east of a
persistent upper trough where onshore flow should continue through
the period.  The next system will slip eastward through the Bering
into western Alaska with another push of moderate to heavy
precipitation with a weak shortwave passing under the base of the
closed low, which is heavier in southeast AK and the AK Panhandle
from Tuesday through next Wednesday.  Temperatures should be
seasonably mild through the period.

Roth

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