Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
308 PM EST Thu Jan 03 2019

Valid 12Z Mon Jan 07 2019 - 12Z Fri Jan 11 2019

Model ensemble means continue to show a fast and progressive flow
regime sending energetic waves eastward across the Northeast
Pacific into late next week.  The preferred storm track remains
well south of mainland Alaska while old occluded lows linger near
the western Aleutians.  Over mainland Alaska, the ECMWF and EC
mean indicate that a cold upper low will slowly retrograde
westward across northern Alaska into northeastern Siberia through
next week.  This will keep much of the frigid air in place
especially across northern Alaska.  On the other hand, the GFS has
been indicating a strong ridge to build northward across Alaska by
the middle of next week, with a definite warming trend setting in.
 However, the latest (12Z) GFS suddenly flipped to a cold pattern
more in line with the 00Z ECMWF.  The 12Z ECMWF solidified this
cold preference by keeping the retrograding upper low well-defined
while tracking a large occluded cyclone south of the Aleutians. 
Given that the ECMWF/EC mean has handled the synoptic pattern the
best for areas south of Alaska lately, we will continue to lean
toward the ECMWF solutions.  Therefore, the latest WPC Alaskan
grids were based on a weighted consensus from these model
solutions: 00Z EC mean, 12Z ECMWF, 12Z GEFS, and 12Z GFS with a
preference to the ECMWF/EC mean.

This model preference means that the frigid temperatures across
Alaska are forecast to linger well into next week.  Nevertheless,
a slow warming trend is indicated toward the latter part of next
week.  In terms of precipitation, northern Alaska will remain dry.
 Farther south, occasional snow mixing with rain is expected
across the Aleutians due to the lingering occluded cyclones.  Some
of the snow should make its way across southern Alaska on Tuesday,
possibly reaching the panhandle on Wednesday with rain mixing in
near the coast.  By Thursday, a large occluded low center should
track south of the Aleutians.

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