Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
615 PM EDT Wed Apr 21 2021
Valid 12Z Sun Apr 25 2021 - 12Z Thu Apr 29 2021
...Overview and Guidance/Uncertainty Assessment...
A quiet weather pattern remains on tap for much of Alaska days
4-8. Latest guidance continues to depict a fairly blocky regime
into medium range time scales. An upper ridge/closed high will
dominate much of mainland Alaska into next week, albeit with
northwest Canada closed vortex energies nudging into the eastern
Interior. In this pattern, closed lows will work into/south of the
Aleutians and slide underneath the upper ridge into an unsettled
western Gulf of Alaska, with additional energies lifting on the
western periphery of the upper ridge. Feel more comfortable in a
blocky pattern to focus on guidance that maintains the mainland
upper ridge on the stronger end of the full envelope of solutions.
The 12 UTC Canadian and 00 UTC ECMWF ensemble mean are in that
camp and their well clustered guidance were blended days 4-8 for
the WPC product suite to provide detail consistent with a pattern
with near average predictability. This solution offers good WPC
continuity.
...Weather/Hazards Highlights...
Most of Alaska should remain dry through much of the period, with
modest precipitation confined to the Aleutians/Alaska Peninsula
and vicinity, particularly associated with a nearby low pressure
system Sunday into Monday. Unsettled maritime conditions are also
likely with this storm as with additional developments into the
Gulf of Alaska later next week that could eventually bring
precipitation into the Southeast Panhandle. Much above normal
temperature anomalies are expected from the Brooks Range down
across the western Interior under the upper ridge, especially this
weekend. Temperatures will meanwhile cool over the North Slope,
the eastern Interior and Southeast Alaska with frontal passages.
Schichtel
Hazards:
-Much above normal temperatures across portions of mainland
Alaska, Sat-Sun, Apr 24-Apr 25.
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