Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
741 PM EDT Wed Mar 31 2021
Valid 12Z Sun Apr 04 2021 - 12Z Thu Apr 08 2021
...Guidance/Uncertainty Assessment...
The latest ECWMF model guidance is less of an outlier than it has
been for the past couple of cycles. However, the CMC and NAM are
now more progressive and now clustered with the rest of the model
solutions. The GFS and its ensemble mean resemble the tracks of
the CMC and NAM however favor a slightly slower evolution as that
of the latest ECWMF. Spread within the guidance does persist,
especially by the mid and late periods so the confidence in
regards to specific details remains somewhat low. A multi-model
blend favoring the GFS solutions was used for this forecast.
...Weather/Hazards Highlights...
Cool and unsettled weather is expected for parts of the Interior
along with some locally enhanced snowfall. Portions of the
southern Mainland and the Southeast will have multiple days with
precipitation possible as an amplified upper trough digs across
the eastern Gulf of Alaska. A system leaving the Bering Sea will
progress into the mainland by the weekend, supporting cooler
temperatures and enhanced snows from western and southwestern
Alaska into the central mainland. An additional western Bering Sea
system potentially could effect the Aleutians by early next week.
These system energies may tend to dig to the lee of a mean upper
ridge built up through the Aleutians and 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
Hazards:
- Heavy snow across portions of mainland Alaska, Sat-Sun, Apr
3-Apr 4.
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