Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
428 PM EDT Tue Apr 10 2018

Valid 12Z Sat Apr 14 2018 - 12Z Wed Apr 18 2018

Ensemble means and even the bulk of deterministic guidance remain
fairly locked into the large scale pattern across Alaska during
the medium range period, which should feature an upper low
dropping south from the Gulf of Alaska while upstream ridging
builds in over the Aleutians and Bering Sea this weekend.  Early
to mid next week, the ridge axis should shift eastward into
western portions of the state as an expansive upper low rotates
into the Bering Sea.  There also continues to be reasonable
predictability with the timing and strength of deep surface lows
crossing into the Bering, one expected to reach the western
Aleutians around 12Z Saturday and a second potentially centering
near St. Paul/St. George around 12Z Wednesday. 

The WPC Day 4-8 forecast was based on a blend of the 00Z GFS/GEFS
mean/ECMWF/ECMWF Ensemble mean/Continuity, with more weight
towards the ECMWF/ECMWF ensemble mean since the GFS still appears
to be an aggressive outlier with energy dropping into western
Alaska early in the forecast period.   


Gerhardt