Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
219 PM EST Thu Jan 24 2019

Valid 12Z Mon Jan 28 2019 - 12Z Fri Feb 01 2019

...Pattern Overview and Guidance and Predictability Assessment...

The overall large scale pattern over Alaska for the medium range
features a weakening shortwave/surface low retreating into Alaska
and northern Canada while behind it a blocky closed upper high
builds over the Bering Straight. Meanwhile, a deep closed upper
low moves into the western Aleutians while multiple waves
progressing eastward in the base of the trough sends a couple of
surface lows into the Gulf of Alaska. Days 4 and 5 show fairly
good large scale model agreement and thus a blend comprising
majority deterministic guidance (GFS/ECMWF) along with some
ensemble mean influence (GEFS/ECENS) worked well. After this time,
forecast spread/uncertainty and run-to-run-variability grows and
so increasing weighting of the ensemble means was used. This
approach maintains good WPC continuity.

...Weather/Hazards Highlights...

The Alaskan southern tier and Gulf of AK should remain in a
pattern with periodic precipitation days 4-8 with a series of
modest systems. Western portions of mainland Alaska and parts of
the Panhandle may see modest snows this weekend into early next
week with the approach of a deepened Bering Sea system and
subsequent trough moving inland early in the period. Meanwhile, a
major upstream low is forecast to affect the Aleutians early to
middle of next week presenting a threat for significant maritime
high winds/waves. Regarding temperatures, much above normal values
(10-20+ degrees) early in the period across interior Alaska should
cool to near normal or slightly below normal values by the end of
next week. 

Santorelli

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