Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
554 PM EDT Sat Nov 05 2022
Valid 12Z Wed Nov 09 2022 - 12Z Sun Nov 13 2022
...Synoptic Scale Overview...
Overall, ridging across southeast AK and western Canada should
generally maintain itself while wavering in intensity this period
while storminess impacts the southern and western extremities of
AK.
...Guidance/Predictability Assessment and Preferences...
Overall, the model guidance shows increasing disagreement due to
differences in the northern stream and southern stream, which has
consequences for cyclone track near the Aleutians. If that isn't
enough, the 12z GFS and 12z ECMWF become outliers with the
strength of a low moving by western Alaska. The Canadian
continues to phase streams and brings a very deep cyclone north to
northwest through the Bering and eastern Siberia. A compromise of
the 12z GFS, 12z ECMWF, 12z Canadian, and 12z UKMET was used
Monday night into Tuesday night before the spread became
overwhelming. With such a variety in the deterministic guidance
from Wednesday night onward, ECMWF/NAEFS ensemble means were
utilized thereafter (using a 70% percentage) to deal with all the
differences seen in the guidance for the pressures, fronts, winds,
and 500 hPa heights. The 19z NBM, 12z ECMWF ensemble mean, and
12z NAEFS mean were used more heavily in the QPF as a consequence,
with the usual 19z NBM heavily used in the remaining grids.
...Sensible Weather and Potential Hazards...,
Parts of Alaska will be cold and dry, particularly the eastern
interior, though moderation will be seen in the AK peninsula as
the flow comes in more off the northeast Pacific and the arctic
high moves farther afield downstream through Canada which should
allow temperatures to recover from their below average values
early on. Cloudy conditions should be dominant through the period
statewide. Rain chances are expected to be highest in the west
and southern parts of the state, with the heaviest rain down
south. Winds should be highest across southwest into
south-central AK as well as the Aleutians, though uncertainty in
the latitude of the cyclone track and depth of systems precludes
much more than gales from being anticipated ashore at this time.
There is higher potential for higher winds in portions of the
Aleutians Wednesday night and Thursday, perhaps storm force if the
track and depth of a pair of cyclones are most favorable.
Roth
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