Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
350 PM EDT Wed Oct 03 2018

Valid 12Z Sun Oct 07 2018 - 12Z Thu Oct 11 2018

An amplified pattern is expected to continue through next week
across the Pacific as ridging maintains its presence between
140-150W. Although the guidance all show a similar longwave
pattern (trough/ridge), the embedded systems in the flow remain
much less clustered. The ECMWF has been more consistent than the
GFS, but in this pattern that may not mean as much. The ensemble
means, at least, were better clustered but much less defined with
the shortwaves but used them as a base and added detail with
nearby deterministic models (mostly the 00Z GFS/ECMWF) along the
line of continuity. The influx of future ex-Typhoon Kong-rey will
introduce additional uncertainty into the forecast but the models
generally takes the extratropical low into the Bering next Wed/Thu
with downstream ridging east of 150W.

This will be a fairly wet pattern for the eastern Aleutians into
southwestern Alaska as the mid-level flow becomes southerly.
Precipitable water values may rise to +2 to +3 sigma next week
(12Z GEFS probabilities of >50% for PW > +2 sigma) and the GEFS
M-Climate relative QPF was about the 98th-99th percentile by next
Tue-Wed. Temperatures will generally be above average due to the
strong ridging except for the Panhandle with the flow mostly out
of western Canada.

Fracasso


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