Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
322 PM EDT Thu May 03 2018

Valid 12Z Mon May 07 2018 - 12Z Fri May 11 2018

...Stormy Aleutians/Bering Sea...

...Guidance/Predictability Assessment and Weather/Threats
Highlights...

Model and ensemble guidance now clusters quite well at medium
range time scales with a seemingly reasonable trend toward a
slightly less progressive and increasingly blocky flow pattern.
This bolsters forecast to above normal confidence levels despite
pattern transition. Deep layered ridging builds from NW Canada to
the Alaskan interior/North Slope next week as a potent upper low
settles into the Bering Sea, with energies sluggish to work
eastward through the Gulf of Alaska. Surface high pressure should
build down from northern Alaska into the interior in this pattern.
Meanwhile, a deep low pressure system with a significant threat
for widespread heavy winds/waves and precipitation will track near
the Aleutians then linger/slowly fill over the southern  Bering
Sea next week. A triple point low and associated weather slowly
working into the Gulf of Alaska should weaken as it encounters
downstream ridging, but this system along with Bering Sea low
proximity should favor main lead wet flow downstream across
southwest Alaska. Trailing shortwave energy rotating around the
Bering circulation may realize a surface front and surface low
developing well south of the Aleutians may then struggle to lift
northeastward toward the Gulf of Alaska later next 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
www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html