Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
611 PM EST Sun Nov 29 2020
Valid 12Z Thu Dec 03 2020 - 12Z Mon Dec 07 2020
...Storm systems are expected to lie over and south of Alaska
during the next week...
A blocky pattern characterized by ridging over Saskatchewan will
keep troughing and shortwave energy moving through portions of the
Alaska region over the next week with a coupe weaker low pressure
systems mainly over the open waters of the Gulf of Alaska this
week. However by this weekend a much stronger to significant
weather system could approach portions of the mainland. Forecast
guidance shows relatively good agreement in the synoptic scale but
as usual there are considerable progression/timing issues that
develop with individual storm systems particularly later in the
forecast period. As such, the WPC blend consisted of a
deterministic beginning using the 12Z ECMWF/GFS/CMC followed by
increasing weight of the ECENS/NAEFS means which resulted in a
blend that shows the latest model trends but maintains some
continuity given the uncertainty discussed above.
Much of the region will continue to experience above normal to
much above normal temperatures for highs and lows with some days
seeing anomalies of 20-30F across the interior areas. Expect the
best potential for below normal temperatures over the
west/southwest part of the mainland and through the
Peninsula/Aleutians, in an area of persistent mid-level troughing
into mid-week. By late in the weekend, if the storm system lifts
closer to the coast, then widespread precipitation and generally
unsettled weather could result in more normal to below normal
temperatures by day 8.
Roth/Taylor
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