Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
223 PM EDT Sat Aug 18 2018

Valid 12Z Wed Aug 22 2018 - 12Z Sun Aug 26 2018

...Guidance/Predictabilty Assessment and Weather Threats...

Models/ensembles continue to offer better than average agreement
on the flow pattern evolution affecting Alaska through the end of
next week, bolstering forecast confidence. The 12 UTC GFS seems
more compatable with GEFS/ECMWF ensemble means and WPC continuity
for the coming week than the 00 UTC ECMWF. A composite blend of
the GFS and ensembles was used to derive the WPC medium range
product suite.

In this pattern, a lead/deep short range low working into southern
Alaska Tuesday and organized precipitation will weaken rapidly
across the inland high terrain and eastern interior Wednesday.
This will be followed by a potent cyclone and focus for high
winds/waves/rainfall across the Bering Sea through midweek to make
landfall into western/southwest Alaska then interior late
week/next weekend. Lead energy transfer also supports triple point
low development downstream over the northern Gulf of Alaska whose
precipitation swath would effect southern then southeastern
Alaska. Forecast spread/uncertainty increases into next weekend
for details with these systems and another potentially deepened
low to amplify then lift over the northern Pacific to threaten the
Aleutians late week.

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