Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
206 PM EDT Tue Jun 26 2018

Valid 12Z Sat Jun 30 2018 - 12Z Wed Jul 04 2018

An upper low and associated trough is forecast to drift east
northeast across northeastern Russia and then into the Chukchi
Sea/Arctic Ocean through the weekend and early next week.  The
trends are for slightly faster forward motion today. Sufficient
clustering of solutions leads to a consensus based approach on the
system's evolution.

A lead upper low near Kodiak Island Fri night drifts east across
the north Pacific/adjacent Gulf of Ak over the weekend.  The
models/ensembles are split on timing of the upper low as the 00z
ECMWF was on the fast edge of the timing distribution, while the
06z GFS was on the slow side of the distribution.  With the 12z
GFS speeding up the system several hours, it looks like an
intermediate solution in between the 06z GEFS mean and 00z ECMWF. 
Manual progs blended the 12z GFS and 00z ECMWF ensemble mean days
4-6, and integrated the 06z GEFS ensemble mean on day 7-8 to use a
blend of the preferred cluster.

In the wake of the departure of the upper trough, heights slowly
build west to east across the lower to mid Aleutians, with the
positively tilted ridge extending northeast across interior
Alaska.  The above normal heights and temperatures favor a pattern
of above normal temperatures in the early to middle portions of
next week across southern Alaska, including in the Aleutians.

Petersen

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