Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
756 PM EDT Tue Mar 30 2021
Valid 12Z Sat Apr 03 2021 - 12Z Wed Apr 07 2021
...Guidance/Uncertainty Assessment...
The latest runs of the model guidance and the ensemble means agree
on the big picture over the course of the extended period, however
there is quite a bit of spread beyond initialization. This spread
does lower the confidence on exactly timing, location and
amplitude of the various features. The ECWMF continues to be near
the fringe of being an outlier, especially in terms to amplitude.
A multi-model and ensemble blend was preferred to help dampen the
noise/spread, with a heftier lean toward the GFS and its mean.
...Weather/Hazards Highlights...
Portions of the Interior may have cool, unsettled weather with
possibly some locally enhanced snowfall Friday thanks to a
lingering upper-level trough. Meanwhile to the south, an amplified
upper trough dug over the eastern Gulf of Alaska will support a
lingering precipitation focus into the Panhandle.
Upstream, an unsettling northern Bering Sea system Friday will
progress into the mainland by the weekend. This should support
some threat of enhanced snows from western and southwestern Alaska
into the central mainland. There is an additional, but uncertain,
western Bering Sea system potential by early next week that could
effect the Aleutians. These system energies may tend to dig to the
lee of a mean upper ridge built up through the Aleutians. This
pattern may favor periodic reinforcement of surface lows from the
northern to eastern Gulf of Alaska that would offer a recurring
threat for lead flow to fuel periods of moderate terrain enhancing
precipitation for southeast Alaska.
Campbell/Schichtel
Hazards:
- Heavy snow across portions of mainland Alaska, Fri-Sat, Apr
2-Apr 3.
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