Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
550 PM EST Fri Dec 06 2019
Valid 12Z Tue Dec 10 2019 - 12Z Sat Dec 14 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 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 pulled farther northwestward on the
other side of the AKPEN like many GEFS members, but preferred to
stay with the larger cluster of solutions. Next system will enter
the Bering and move east-southeastward through the Aleutians.
Blend of the 12Z ECMWF/GEFS mean and 00Z ECMWF ensemble mean
forged a good starting point for the latter days that was a bit
slower than the forecast 24 hrs ago.
After a brief cold snap over interior portions of Alaska,
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 in
the ECMWF ensemble mean). 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 into next
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
Hazards:
- Heavy precipitation across portions of southern Alaska, Mon, Dec
9, and Thu, Dec 12.
- High significant wave heights for coastal portions of mainland
Alaska, Mon, Dec 9.
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