Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
721 PM EDT Thu Nov 04 2021
Valid 12Z Mon Nov 08 2021 - 12Z Fri Nov 12 2021
...Overview and Model Guidance...
Mean upper level low pressure will be maintained over the Gulf of
Alaska region as an upper low rotates aloft and several shortwaves
reinforces troughing from over Alaska to the Eastern Pacific. This
sends various surface low pressure systems well south of the
Aleutians and into the Gulf as surface high pressure builds in
over the Mainland and western Aleutians. The 12z deterministic
guidance from today remains in relatively good agreement on the
overall, synoptic scale, pattern. Particularly the second half of
the period, models begin to show increasing uncertainty regarding
the details, placement, and strength of individual systems. WPC
favored a blend of the deterministic guidance (12z GFS, ECMWF,
CMC, and UKMET) through day 5/Tuesday, with increasing
contributions from the ensemble means thereafter to account for
and help mitigate the differences. This also maintains fairly good
continuity with yesterdays WPC forecast.
...Weather/Hazard Highlights...
Overall, the Alaska region should be relatively quiet in terms of
impactful precipitation and hazards with much of the mainland
remaining dry, with the exception of a few interior mountain snow
showers. Showers remain likely through much of next week from the
eastern Aleutians to the Panhandle as storms track well to the
south. Periods of moderate to locally heavy rainfall are possible
across southern portions of the Panhandle as a couple of surface
lows deepen in the Gulf sending their cold fronts into western
Canada.
For temperatures, the North Slope region of Alaska may begin the
period Monday above normal, but (with the exception of the far
northern coast) should trend cooler by the end of the week. The
rest of Alaska will also see a cooling trend through the week as
surface high pressure builds in across the region. Portions of
western and southwest Alaska could see daytime highs as much as 10
to 20+ degrees below normal.
Santorelli
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 outlook 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