Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
329 PM EST Mon Nov 04 2019
Valid 12Z Fri Nov 08 2019 - 12Z Tue Nov 12 2019
Pattern remains quite uncertain from the central Pacific
northeastward across Southeastern Alaska/Panhandle. Upper high
forecast has trended toward a quicker weakening around Sunday
before again (perhaps) building to the north of northeastern
Russia (Wrangel Island) next week. This still favors troughing
south of the Aleutians into the southern Gulf and Panhandle, with
increased troughing into the Bering Sea. Uncertainty increases
from west to east along 50N with multiple smaller-scale features
lifting out of the northeastern Pacific and weakening before a
more coherent/significant system enters the picture next week.
Blend of the 12Z GFS/00Z ECMWF and their ensemble means offered a
reasonable starting point as the ill-defined means themselves were
at least agreeable if not detailed. The GFS/ECMWF were close
enough to their means that a nearly 50/50 blend maintained some
detail at the expense of some continuity from the previous
forecast. However, change in the upper pattern by this degree in
the ensembles necessitated a larger change than usual in some
areas. UKMET/Canadian departed from the ensemble mean consensus
early in the period around late Friday.
Rain/snow should mostly be confined to coastal and near-inland
areas from the Aleutians and across Kodiak Island into the
Panhandle as old occlusions weaken offshore. Heaviest amounts will
likely target the southern Panhandle near the better convergence
and moisture axis with each system. Several inches of liquid
precipitation are possible over the 5-day period around Annette.
Temperatures will remain near to above average over much of the
state, especially the North Slope and southwestern
Alaska/Southcentral where 850mb temperature anomalies will remain
near +1 to +2 sigma. The exception will be over the eastern
interior beneath surface high pressure and over the Panhandle
where the slipping Canadian high will funnel in cooler
temperatures on easterly flow later this week into the weekend.
Fracasso
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can also be
found at:
https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html