Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
652 PM EST Fri Feb 04 2022
Valid 12Z Tue Feb 08 2022 - 12Z Sat Feb 12 2022
...Overview...
The pattern over Alaska during the medium range period will
feature an elongated upper trough over parts of the mainland,
which is likely to have an embedded upper low over the western
mainland/Bering Sea at least Tuesday-Thursday of next week, while
overall ridging builds across the eastern Pacific and into
northwestern North America. This pattern will allow for surface
low pressure systems to track between these upper-level features,
initially into the Gulf of Alaska Tuesday and likely farther west
around midweek. These will spread precipitation especially into
southern Alaska, with the heaviest precipitation over Southcentral
Alaska and into the Panhandle, with some snow farther north in the
mainland around Wednesday to Friday.
...Guidance/Predictability Assessment...
Guidance is agreeable with the potential for an upper low drifting
near western Alaska and the Bering Sea Tuesday through Thursday,
but with some variations on the exact position. As has been the
case over the past couple of days, ECMWF deterministic runs in
particular show this feature farther east of consensus. The WPC
Alaska desk saw a similar trough/ridge pattern a couple of weeks
ago where the ECMWF was too far east, and teleconnections relative
to the positive height anomalies associated with the building East
Pacific upper ridge show that higher heights over Alaska are
favored in that pattern. For these reasons as well as continuity,
leaned away from the eastern EC solution. The GFS runs were
periodically west of consensus, and ended up favoring the position
of the ensemble means and the CMC (which was the closest
deterministic model) as it meanders. Guidance generally shows
troughing remains across the northwestern part of the state but
easing toward the end of next week, though with large differences
in the details among deterministic guidance.
Farther south, the surface low early Tuesday has good agreement
for a position in the Gulf of Alaska from the ECMWF and GFS, with
the CMC a bit farther south. Then, consensus places another low
system into southwest Alaska early Wednesday, but with a bit more
variation in exact position and the ECMWF throwing a wrench in the
agreement with another, stronger low over the Gulf at that point.
It appears the upper low/trough orientation and the low
predictability shortwaves swinging around the southern side of it
are affecting the surface pattern in this way, so at this point
leaned toward a non-ECMWF solution for that. By the latter part of
the week, the general storm track appears to be south of the
Aleutians with possibly some potent surface lows. However, the
specifics are quite variable and forecast confidence for any
particular solution is low. The initial WPC model blend was based
on mainly deterministic solutions early but gradually phased in
the more agreeable ensemble means to the majority by the end of
the period, which maintained good continuity from the previous
forecast.
...Weather/Hazard Highlights...
Southwesterly flow between the Bering Sea upper low/trough and the
East Pacific/far western Canada ridge will support wet weather
over southern Alaska during most of next week. Individual surface
lows will periodically help to focus heavier episodes of rain in
low/coastal areas and heavy snow in higher elevations. Highest
totals are likely to be from the southeastern coast through the
Panhandle, while amounts over locations farther west will depend
more on exact storm track. Each storm may also produce brisk to
strong winds and rough seas between the Aleutians/Alaska Peninsula
and the Panhandle. Some snow may extend farther north into the
mainland mid-late week based on a most likely storm track into the
southwestern mainland. The majority of the state should see below
normal temperatures early next week, with Southcentral and the
Panhandle tending to be the exception with above normal readings.
The evolving upper pattern should promote a warmer trend by
mid-late week, ultimately confining most of the below normal
temperatures to the far western mainland.
Tate/Rausch
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Mon-Thu, Feb 7-Feb 10.
- Much below normal temperatures across portions of mainland
Alaska, Mon-Wed, Feb 7-Feb 9.
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