Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
335 PM EDT Sat Jul 14 2018

Valid 12Z Wed Jul 18 2018 - 12Z Sun Jul 22 2018

The model guidance remains in general agreement concerning the
overall synoptic scale pattern across the Bering Sea, northeast
Pacific, and the Alaska mainland through about Thursday, with the
biggest differences across the Arctic region with perturbations
rotating around the polar vortex.  The 00Z ECMWF becomes more
amplified with the shortwave trough tracking southeast across
eastern Siberia and across the Bering Sea by Friday morning, and
this is where greater uncertainties enter the forecast domain. 
The 12Z GFS becomes slower with the upper trough over the Gulf of
Alaska by Friday, with the GFS and CMC farther east.  To account
for the increasing model spread by Friday and beyond, an
increasing portion of the GEFS and EC means was incorporated,
along with some previous WPC continuity.

The western portion of the Alaska mainland and much of the
Aleutians will become unsettled on Wednesday as the disturbances
from the Bering Sea approach the state.  Widespread organized
rainfall and some thunderstorms are possible across much of the
Interior for Thursday and going into Friday ahead of the deep
trough, courtesy of sustained moisture advection from the north
Pacific.  An enhanced area of rain is expected near the southern
Alaska coast and towards the Panhandle region for Friday and into
Saturday.  The warmest temperatures are expected on Wednesday and
Thursday across east central Alaska ahead of the front, with
cooler weather arriving by the end of the week with increased
cloud cover.

D. Hamrick



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