Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
216 PM EDT Mon Jul 16 2018

Valid 12Z Fri Jul 20 2018 - 12Z Tue Jul 24 2018

...Guidance and Predictability Assessment...

Latest model and ensemble forecast spread has become less
problematic days 4-7 and now overall offer near normal continuity,
albeit with some lingering timing and amplitude differences with
embedded systems. The 00 UTC ECMWF and 00 UTC GEFS/ECMWF/NAEFS
ensemble means provide max clustering and continuity and their
composite was used as the starting point for the WPC medium range
product suite. 

...Weather Highlights and Hazards...

A closed low spinning over the Arctic well north of the state is
now expected to only force modest height falls and wavy surface
front southeastward from the Chukchi Sea and Bering Strait to the
North Slope. This seemingly reasonable trend still allows the
front and scattered precipitation to linger over the next week.

An amplified and again slowed system progression now evident
underneath meanwhile starts with a lead system cresting the
southeastern Alaskan panhandle late Thursday along with lingering
precipitation. Upstream, mid-upper level trough energy should
support a slowed/organized surface low and frontal system approach
to fuel widespread precipittaion across southwest and southern
Alaska Friday through the weekend. Additional deepened shortwave
energy slated to dig behind this feature may renew weekend focus
down over the Aleutians then southwest Alaska.

Schichtel

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