Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
139 PM EST Sat Dec 15 2018

Valid 12Z Wed Dec 19 2018 - 12Z Sun Dec 23 2018

Upper troughing is forecast to remain anchored along 160-170W next
week with ridging building into eastern Alaska. Pacific systems
will track south of the Aleutians and toward the Gulf/Panhandle as
the strong jet off Japan (150-170kts) only wobbles slightly
north-south. The 00Z ECMWF ensemble mean has been more consistent
than the GEFS mean and was more defined/deeper/amplified as well
which fit the preference given the up/downstream pattern. The 00Z
ECMWF and some of the 06Z/12Z GFS fit with the ensemble idea and
used various weights of those models to form a starting point.
This maintained good continuity from the previous forecast with
adjustments toward deeper and slower system progression.

Temperatures will slowly rise from below average to near or above
average over much of the state (especially eastern areas of the
interior) as heights build and lower level temperatures creep
upwards. Western Alaska may stay below average under the upper
trough. Precipitation will be favored over Southcentral (southern
Kenai) eastward to the Panhandle given the storm track with modest
amounts through the period. Ensembles focus most of the QPF into
southern British Columbia.

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