Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
233 PM EST Tue Feb 12 2019

Valid 12Z Sat Feb 16 2019 - 12Z Wed Feb 20 2019

Upper ridging along and east of 150W (through interior eastern
Alaska) will give way to wavy zonal flow by next week atop ridging
just south of the Aleutians. The 12Z GFS and 00Z ECMWF clustered
fairly well with the 06Z GEFS mean and 00Z ECMWF ensemble mean
through about next Mon/Tue with the lead system into
western/southwestern Alaska this weekend and then a significant
system crossing the western Aleutians late Sunday and moving into
the Bering Sea Monday. Timing differences were the main point of
contention rather than track or intensity, so a majority
deterministic blend worked well to start. This still yielded 40+
kts wind along/ahead of the front across the Aleutians into the
Bering late Sun into Mon with 30-35 kts behind the surface low.

For next Tue/Wed, Bering system will translate eastward as the
flow becomes quasi-zonal. Next system will perhaps approach the
western Aleutians at the end of the period but the ensembles
differ on that timing/track. Otherwise, the longwave pattern was
in good or very good agreement as the bigger differences existed
south of the area in the mid-latitudes and toward Hawai'i.

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