Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
238 PM EST Tue Jan 01 2019

Valid 12Z Sat Jan 05 2019 - 12Z Wed Jan 09 2019

Ensemble means continue to show decent agreement on the general
synoptic pattern evolution in the vicinity of Alaska through the
medium range period.  Below normal upper-level heights are
forecast to cover much of Alaska as a fast and progressive flow
regime continues to bring energetic waves across the Northeast
Pacific.  A preferred storm track is noted from south of the
Aleutians across the Northeast Pacific before turning northward
and dissipating near the Alaskan Panhandle. Farther north,
guidance continues to indicate the formation of an upper high
cutting off over eastern Siberia, which would open up much of
Alaska to drier and and colder northerly flow from the Arctic
Ocean.  Indeed, a cooling trend is indicated along the coastal
sections of Alaska with temperatures 20 to 30 degrees below
normal.  Meanwhile, a gradual warming trend is indicated for
interior Alaska.

With the deterministic solutions continue to show a high degree of
run-to-run variability, the WPC Alaskan grids are mainly based on
the ensemble mean solutions from global models.  The ECMWF
ensemble means continue to show the highest degree of run-to-run
stability whereas the GFS would occasionally spin up spurious low
pressure centers toward the west coast of North America, even into
the short range period.  Therefore, the latest WPC Alaskan grids
were based on a weighted consensus from these model solutions: 00Z
EC mean, 12Z ECMWF, 12Z GEFS, and some 12Z GFS.

Kong


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