Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
239 PM EST Wed Jan 02 2019

Valid 12Z Sun Jan 06 2019 - 12Z Thu Jan 10 2019

Model ensemble means continue to show decent agreement on the
general synoptic pattern evolution in the vicinity of Alaska
through the medium range period.  A fast and progressive flow
regime continues to bring energetic waves across the Northeast
Pacific.  The preferred storm track remains well south of mainland
Alaska while old occluded lows linger near the western Aleutians. 
Guidance indicates an upper-level cut-off high retrograding toward
the north into the Arctic Ocean as below normal upper-level
heights linger over mainland Alaska.  Temperatures are expected to
be below to much below normal over Alaska with a possible warming
trend over southwestern Alaska by the middle of next week. 
Occasional snow mixing with rain is expected across the Aleutians
due to the lingering occluded lows.  Otherwise, only some snow
could make it into southwestern and south coast of 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 continues to be problemetic due to
occasional spin-up of spurious low pressure centers over the
Northeast Pacific.  Therefore, the latest WPC Alaskan grids were
based on a weighted consensus from these model solutions: 00Z EC
mean, 00Z ECMWF, 06Z GEFS, and 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