Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
257 PM EST Fri Jan 25 2019

Valid 12Z Tue Jan 29 2019 - 12Z Sat Feb 02 2019

Upper pattern across much of the eastern Pacific is quite
uncertain from the sub-tropics northward into the Arctic. The
forecast in the medium range depends on the evolution of the
closed upper high near the Bering Strait and a weakening lead
closed low near the western Aleutians on Monday and the amount of
digging heights across the interior in addition to where a
mid-latitude shortwave or even closed low travels near the
Panhandle next Thu-Fri. The ensembles show nearly all solutions
offered by the recent deterministic runs with no clear indication
as to which way to trend. The 00Z ECMWF ensemble mean seemed least
resistant to multi-day changes so opted to rely mostly on its
forecast later next week. The 12Z GFS and 06Z GEFS mean were
included for a bit of detail as well as to compensate for
uncertainty. This would allow the upper high to drift
northwestward and allow at least some troughing to slip southward
into the Gulf (combined with the Bering system Mon-Tue) before the
pattern perhaps relaxes next weekend.


Precipitation will focus along Southcentral into the Panhandle
with the lead systems in the Gulf that will weaken and head east
Mon-Thu. Colder temperatures will push southward on the east side
of the upper high but the strength of the cold push is uncertain.
Blend of the 12Z NBM and 00Z ECMWF ensemble mean was a good
starting point. Next Bering system will spread more rain/snow
eastward Thu-Sat.


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