Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
622 PM EDT Thu May 13 2021
Valid 12Z Mon May 17 2021 - 12Z Fri May 21 2021
...Overview...
Rather unpredictable smaller wavelength pattern will mostly
feature troughing along 50N and far NW Alaska as weak upper
ridging meanders over the Interior and NW Canada.
With low pressure mostly over the northern Pacific into the Gulf,
appreciable precipitation will be limited to the Panhandle and
Aleutians.
...Guidance/Predictability Assessment...
The models have really been struggling with how the systems evolve
out of the western/central Pacific next week, and continue to
shift with each cycle. Even the ensemble means have been
susceptible to changes in timing, though can still show agreement
with each other. Felt a broad consensus was appropriate given the
less-than-normal predictability (though probably par for the
pattern) among the 12Z GFS/ECMWF/Canadian to start (with the
GEFS/ECMWF ensemble means), transitioning to a mostly ensemble
mean blend with only some details from the 12Z ECMWF. Preferred to
keep the system next Thu just south of the Aleutians based on the
ensemble overlap rather than have it lift into the Bering Sea.
...Weather/Threats Highlights...
Weak troughing over the mainland into the Gulf will promote
scattered showers across the Interior/North Slope into the
Panhandle early in the week. A more defined system may approach
the Aleutians around the middle of next week (lead system may
dissipate around Wednesday) with light rain for the island chain.
Temperatures will be within several degrees of normal over much of
the state, but near to below normal over the Panhandle.
Fracasso
Hazards:
No significant hazards are expected over Alaska during this
forecast period.
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