Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
404 PM EDT Fri Aug 03 2018

Valid 12Z Tue Aug 07 2018 - 12Z Sat Aug 11 2018

The 12Z GFS and 00Z ECMWF both showed an occluded front
approaching Southwest Alaska by Tuesday and moving into
south-central Alaska by Wednesday.  The next system will move
south of the Aleutians by Thursday/Day 6.  The 00Z ECMWF and 12Z
GFS lined up well even by this point. A system in the western
Pacific is forecast to loop around high pressure centered across
the eastern Pacific and approach Alaska between Friday/day 7 and
Saturday/day 8. The GFS is much faster and a bit more aggressive
with this extratropical system, whereas the ECMWF is slower. The
00Z CMC was much faster than even the 12Z GFS.  However, the 00Z
GEFS and 00Z ECENS have better agreement showing a deepening low
near the Aleutians--even the 00Z CMC mean reflecting this
especially by day 8.  WPC used a blend of the 12Z GFS/00Z ECMWF
with some of the 00Z CMC through Day 5, dropping the CMC
completely by day 6 due to its treatment with the western Pacific
system.  By then, increased the usage of the 00Z ECENS/00Z GEFS
through the rest of the period.

Overall, the pattern is still expected to be wet for the
panhandle. By Tuesday, a frontal system will sweep across the
Aleutians and deliver moderate to heavy precipitation along this
area in addition to the Alaska Panhandle and southeast Alaska. 
Rainfall chances will begin to increase from west to east as the
potential deepening system approaches the Aleutians on Friday and
into Saturday. Temperatures are expected to be seasonably mild
through the period.


Reinhart



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