Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
524 PM EST Mon Mar 01 2021
Valid 12Z Fri Mar 05 2021 - 12Z Tue Mar 09 2021
...Overview and Guidance/Uncertainty Assessment...
Larger scale flow transition is overall decently handled in
guidance across medium range time scales, but the models struggle
with embedded system emphasis and complex interactions that seem
better resolved with the steadier ensemble means this weekend into
next week. Accordingly, favor a solution close to the 12 UTC
GFS/ECMWF Day 4/Friday before transition Saturday to the
compatible 12 UTC GEFS/ECMWF ensemble means and 19 UTC National
Blend of Models Sunday-next Tuesday. This forecast strategy
maintains good WPC product continuity in a pattern with near
average overall predictability.
...Weather/Hazards Highlights...
A closed mean upper vortex will anchor over northeast Russia days
4-8. While the brunt of storm energies focus from an unsettled
Bering Sea up into the Arctic Ocean, a series of ejecting and
weakening systems on the eastern periphery of the large
circulation will bring several rounds of moderate snows
increasingly onshore into western/northwestern Alaska and the
Interior in active flow. These systems also offer some maritime
threats and some potential for coastal high winds and associated
wave/ice effects.
Meanwhile, ample upper trough energies extending down over the
Bering and Aleutians are slated to break eastward into an also
unsettled Gulf of Alaska. This will support low developments over
the Gulf with lead focus digging through the region Friday-Sunday
and an additional potential period slated for early next week.
These systems offer a moderate maritime threat and the potential
for enhanced precipitation onshore mainly for the AKPen/Kodiak
Island and into southern Alaska.
Schichtel
Hazards:
- High winds across portions of mainland Alaska and the Aleutians,
Fri, Mar 5.
- High winds across portions of mainland Alaska, Sun, Mar 7.
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