Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
616 PM EST Fri Dec 25 2020
Valid 12Z Tue Dec 29 2020 - 12Z Sat Jan 02 2021
...Overview and Guidance/Uncertainty Assessment...
Upper troughing in the Bering will translate ESE into the southern
Gulf/Northeast Pacific later next week as ridging holds over the
Interior/eastern Alaska/NW Canada. Relatively weak systems will
rush through the North Pacific around the upper low's circulation
along 50-55N. These systems will be hard to time so a broad blend
of solutions offered a reasonable starting point. By next
Thursday, favored the ensemble means as a best guide with more
weight toward the better-defined and slightly slower 00Z ECMWF
ensemble mean vs the 12Z GEFS mean as a better-defined system
moves into and through the Bering Sea. Trend has been a little
quicker but still preferred not to be as quick as the 12Z GEFS
mean. Used a blend of the ECENS and the 12Z NAEFS mean which would
take the parent low and then triple point low eastward into next
Saturday.
...Weather/Hazards Highlights...
Generally lighter and scattered rain/snow is forecast for Tue-Thu
with the quicker-moving systems that stay generally offshore. By
the end of next week, more organized rain/snow will push through
the Aleutians and along the AKPen and southern coastal areas.
Triple point development could enhance precipitation over Kodiak
and southeastern areas of the Kenai Peninsula. Temperatures will
generally be near to above normal through the period, especially
over western areas of the mainland.
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 mainland Alaska, Mon-Tue,
Dec 28-Dec 29.
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