Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
520 PM EST Sat Mar 06 2021
Valid 12Z Wed Mar 10 2021 - 12Z Sun Mar 14 2021
...Overview and Guidance/Uncertainty Assessment...
An upper low near the East Siberian Sea will drift northward
toward the Pole with quasi-zonal flow underneath it across the
North Pacific/Aleutians. The flow has lingering potential to
become unstable, leading to wave-breaking and a closed low (or
two) across the mid-latitudes, but should otherwise remain mostly
west-to-east along 50N. Consensus has drifted toward a
less-developed system into the Gulf Thu by way of differing
northern vs southern stream speeds. The 12Z GFS and ECMWF were
comparable enough toward a bit quicker evolution to use as a base,
even though the ECMWF ensemble mean was still quite
slow/developed. Felt the deterministic models may be leading the
ensembles a bit, but at least the 12Z Canadian ensemble mean was
in line with the GFS/ECMWF as the system moves into the Panhandle
early Fri. To the west, uncertainty increases with the details of
the Bering system but a consensus/ensemble blend sufficed.
Amplifying trough/ridge pattern may slow the system into western
Alaska next weekend.
...Weather/Hazards Highlights...
High pressure will settle into the Interior and Southcentral
Thu-Sat with colder temperatures 10-15 degrees below normal. Gulf
system will track to its southeast bringing the bulk of the
rain/snow to the central/southern Panhandle. Next system in the
Bering will bring windy conditions and some rain/snow to the
islands as the parent low stays well northwest toward northeastern
Russia. Milder temperatures will precede the Bering system on
southerly flow from west to east next weekend, but the Panhandle
and southeastern areas will see below normal temperatures as the
surface high drifts into NW Canada.
Fracasso
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