Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
537 PM EDT Wed Mar 24 2021
Valid 12Z Sun Mar 28 2021 - 12Z Thu Apr 01 2021
...Powerhouse weekend Bering Sea low to slam into the Alaskan
mainland into early next week...
...Guidance/Uncertainty Assessment...
The latest model and ensemble solutions are much better clustered
than normal days 4-8, further bolstering forecast confidence in a
stormy pattern. The 12 UTC GFS/ECMWF seem most reasonable
(Sunday-Tuesday), while the 12 UTC GFS and the 12 UTC GEFS/ECMWF
ensemble means seem best clustered days 7/8 (Wednesday-next
Thursday). This methodology maintains excellent WPC continuity.
Remaining guidance options are also well clustered at mid-larger
scales.
...Weather/Hazards Highlights...
A lead system with amplified upper trough support will work emerge
over the eastern Gulf of Alaska this weekend. This will support a
threat for terrain focusing heavy precipitation into the Alaskan
Panhandle before exiting the region. Upstream, a powerhouse low
with highly favorable upper support is meanwhile expected to
emerge back into the Bering Sea this weekend and provide a
significant maritime and Aleutians threat. The storm is expected
to reach/spread highly unsettled conditions over the mainland then
the Gulf of Alaska late weekend through next midweek. This will
include a likely threat of enhanced wrapping snows/precipitation
and high winds/waves. This continues to have a strong guidance
signal to be a major and protracted storm.
Schichtel
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Sat, Mar 27 and Tue-Wed, Mar 30-Mar 31.
- Heavy snow across portions of mainland Alaska, Sun-Mon, Mar
28-Mar 29.
- High winds across portions of mainland Alaska and the Aleutians,
Sun-Mon, Mar 28-Mar 29.
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