Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
418 PM EDT Fri May 25 2018

Valid 12Z Tue May 29 2018 - 12Z Sat Jun 02 2018

Model guidance is fairly well aligned early in the medium range
period, with the bulk of deterministic guidance showing a similar
evolution for an occluded front sweeping through the Bering Sea
and a surface low weakening near the Alaska Panhandle on Tuesday. 
However, uncertainty develops fairly quickly with the details of
upstream shortwave energy tracking south of the Aleutians and
towards the Gulf of Alaska next Wednesday into Thursday.  The WPC
forecast for Days 4-6 used a blend more weighted towards the ECMWF
rather than the GFS, since the ECMWF has been more consistent with
the timing and amplitude of the shortwave as well as an associated
surface reflection.  Beyond Day 6/Thursday, deterministic guidance
continues to show large run-to-run changes with any potential
strong Pacific lows impacting the state late next week, so the WPC
forecast stayed close to ensemble mean guidance for Days
7-8/Friday-Saturday.         

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
www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html


Gerhardt