Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
549 PM EST Fri Mar 12 2021
Valid 12Z Tue Mar 16 2021 - 12Z Sat Mar 20 2021
...Overview and Guidance/Uncertainty Assessment...
The latest guidance continues to suggest a blocky pattern early in
the period from the Bering Sea through much of the eastern
Pacific. Here, the latest deterministic guidance shows reasonable
agreement for day 4 and day 5 and blends well from continuity. By
day 6 however, there is increasing model spread with respect to
the evolution of shortwave energy around 160W and its phasing with
northern stream energies. The GFS and GFSP were quicker to lift
this feature through the Aleutians while the ECMWF/CMC hold it
back and lift it more to the north/northwest. Downstream effects
from the GFS mean a faster/flatter flow over the eastern Pacific
developing by day 7 while the ECMWF/CMC offer a more blocky
amplified solution. At the surface, a couple waves of low pressure
will lift toward the southeast coast and southern mainland early
in the period then with some ridging expected to develop aloft for
day 6-8, a more benign stretch of sensible weather is forecast.
The WPC blend consisted of the 12Z ECMWF/CMC/GFS/UKMET blend for
day 4 and day 5 followed by mostly a ECENS/NAEFS blend for day 6-8.
...Weather/Hazards Highlights...
Aside from possible waves of low pressure brushing or affecting
the southeastern coast and Panhandle early on, the rest of the
period is increasingly looking relatively quieter from a sensible
weather perspective, especially for most of the mainland. Aside
from the North Slope (where temperatures are forecast to be above
normal), the rest of the region is expected to see slightly below
normal temperatures.
Rausch/Taylor
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