Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
529 PM EST Thu Feb 4 2021
Valid 12Z Mon Feb 8 2021 - 12Z Fri Feb 12 2021
...Overview and Guidance/Uncertainty Assessment...
An upper level low that is expected to initially be over the Yukon
on Monday is expected to slowly settle in over central and
northern Alaska by the middle to end of next week. This will tend
to set up a block pattern across the Alaska region for the medium
range period. Meanwhile, a narrow ridge axis will likely exist
across the Aleutians and Bering Sea region that extends northward
from the North Pacific. A weak and quasi-stationary surface low
pressure is expected over the northern Gulf of Alaska with
multiple shortwaves pivoting around the main upper low over the
mainland. There is also the increasing possibility that a strong
surface low could affect the western Aleutians by Wednesday. It
is also interesting to note that a mega surface high just north of
the Arctic Coast, on the order of 1060+ mb, could come close to
setting high pressure records for Barrow (Utqiagvik). In terms of
the models, the 12Z GFS stood out from the model consensus by
midweek with keeping the core of the upper low over far
northeastern Alaska, whereas the CMC/ECMWF and the ensemble means
favored a solution farther southwest. Elsewhere, there are modest
model differences with the overall synoptic scale pattern, and
incorporating the CMC/ECMWF/some GFS along with some of the
ensemble means served as a good starting point, and less of the
GFS by Wednesday and beyond.
...Weather/Hazards Highlights...
Coastal low pressure over the Gulf of Alaska will tend to focus
periods of snow across the southeastern coast and the southeastern
Panhandle through the upcoming week. It appears that the heaviest
precipitation is most probable around Wednesday for this region,
and potentially for the central and western Aleutians depending on
the track of the next storm system. Depending on the eventual
strength of that storm, gusty winds could eventually become a
concern, but confidence is currently limited. Today's guidance
preferences would yield mainly light to moderate activity for most
of this time period. In terms of temperatures, it will likely be
bitterly cold across much of central and northern Alaska with
widespread 30 below readings expected north of the Alaska Range,
and perhaps as extreme as 50 below for the normally colder
locations.
Hamrick
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
Hazards:
- Much below normal temperatures across portions of mainland
Alaska, Sun-Thu, Feb 8-Feb 11.
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