Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
546 PM EST Sat Dec 07 2019
Valid 12Z Wed Dec 11 2019 - 12Z Sun Dec 15 2019
Upper ridging is forecast to drift slowly north-northwestward out
of the Yukon into the Arctic Ocean late next week into the
weekend. This will favor reinforced/reinvigorated troughing to its
southwest out of the Bering Sea and also from the North Pacific.
Main system of interest will be a wound-up robust low moving
toward Kodiak next Wed-Thu per the consensus of the 12Z
ECMWF/UKMET/GEFS mean and 00Z ECMWF ensemble mean. 12Z GFS again
pulled farther northwestward on the other side of the AKPEN like
some ensemble members, but preferred to stay with the larger
cluster of solutions that linger the parent low just east of
Kodiak by early Fri. Next system will enter the Bering and move
east-southeastward through the Aleutians, with a trend toward a
bit quicker progression after a bit slower progression two days
ago. 12Z GFS fit well with the consensus with the Bering system
and was brought into the blend again for next weekend. This system
may slide into the Gulf with perhaps triple point redevelopment
around Kodiak.
Temperatures will largely be near/above average with a southerly
component to the flow and near/above average heights and low level
temperatures (850mb temperature anomalies about +1 to +2 sigma).
Precipitation will be focused along the coast from Southcentral to
the Panhandle around the occlusion along with stiff easterly
winds. Some rainfall could be heavy along the coast with
significant snowfall inland and in mountainous areas next week
before a drier pattern between systems.
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