Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
451 PM EST Thu Jan 27 2022
Valid 12Z Mon Jan 31 2022 - 12Z Fri Feb 4 2022
...Overview...
The Alaska domain will likely experience a blocky upper level
pattern through the first few days of February with a ridge axis
remaining anchored in place over the eastern Gulf region and also
across eastern Siberia, with a col over western mainland Alaska.
A large upper level gyre is expected just south of the western
Aleutians with multiple shortwaves rotating northward towards the
eastern Aleutians and the Alaska/Kenai peninsulas with several
rounds of rain/snow expected.
...Guidance/Uncertainty Assessment...
Overall, the 12Z guidance and the ensemble means are in relatively
decent agreement on the overall synoptic scale pattern across
mainland Alaska and western Canada through Wednesday. Similar to
the past couple of days, the greatest model and forecast
uncertainty resides over the Bering, Aleutians, and North Pacific
with multiple shortwave perturbations pivoting around a large
scale upper level gyre, with significant timing differences with
the individual shortwaves as they lift northward over the
Aleutians and then the Bering. A weaker disturbance makes it
farther east over the northern Gulf region by the middle of next
week, and the GFS/ECMWF/CMC support this scenario. Given the
model uncertainties over the Bering/Aleutians later in the
forecast period, an ensemble mean approach appears prudent as a
starting point for now.
...Weather/Hazard Highlights...
Arctic high pressure slowly weakens during the medium range
period, but keeps most of mainland Alaska dry and cold. Snow
showers and gusty winds are likely for the southern coast from the
Kenai Peninsula to the southeast panhandle as a weak low pressure
system develops along a stationary boundary. Some of this snow
could be heavy at times on Thursday with greater onshore flow
expected.
Meanwhile, a number of uncertain storm systems in regards to
timing offer the potential to bring highly unsettled periods of
wet and windy weather to the Aleutians through this period, and
potentially with slow erosion of the Omega block pattern. Most of
the Interior should be near to below average for temperatures, and
generally above average for southwestern Alaska and the Aleutians.
Hamrick
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Thu, Feb 3.
- Heavy precipitation across portions of the Aleutians, Mon-Wed,
Jan 31-Feb 2.
- High winds across portions of the Aleutians, Sun-Wed, Jan 30-Feb
2.
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