Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
648 PM EDT Thu Apr 01 2021
Valid 12Z Mon Apr 05 2021 - 12Z Fri Apr 09 2021
...Guidance/Uncertainty Assessment...
The latest guidance over the Alaska region for the extended range
period is mostly in agreement with the large scale/synoptic
pattern, though continue to show timing and detail differences,
particularly later in the period. A majority deterministic model
blend (between the 12z GFS and 12z ECMWF) served well as a
starting point for the first half of the period. After that, some
differences in timing of ridging across the Bering and the next
system upstream led to more weighting of the ensemble means the
rest of the week. This solution favors renewed surface low
pressure in the Gulf of Alaska and troughing along the Panhandle
region. High pressure should dominate across the Bering Sea and
much of the Aleutians through day 7, with the next deep surface
low entering the western edge of the domain by day 7-8, dragging a
cold front into the Western Aleutians. Initial surface troughing
over the mainland should be replaced by high pressure across most
of the state by the end of next week.
...Weather/Hazards Highlights...
A weakening surface low along the southern coast may continue to
support some snowfall across portions of interior Alaska through
Monday, although the heaviest snowfall is expected before the
start of the medium range period this weekend. Continued low
pressure across the eastern Gulf should keep showers in the
forecast through much of the week for Southeast Alaska and the
Panhandle. The rest of the mainland should dry out after Monday as
cold high pressure settles in. This would allow below normal
temperatures to expand across almost all of Alaska, with the
coldest anomalies (as much as 20-30+ below normal) across the
central mainland region. The next surface low entering the Bering
Sea by later in the week should bring leading precipitation into
the western and central Aleutians next Thursday and Friday.
Santorelli
Hazards:
- Heavy snow across portions of mainland Alaska, Sun, Apr 4.
- Much below normal temperatures across portions of mainland
Alaska, Tue-Thu, Apr 6-Apr 8.
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