Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
639 PM EST Mon Jan 24 2022
Valid 12Z Fri Jan 28 2022 - 12Z Tue Feb 01 2022
...Overview...
The latest guidance continues to support the development of an
Omega block pattern setting up over the Alaska region with little
change through at least the weekend and into early next week.
Storm tracks remain confined to the Gulf where a couple of systems
may bring unsettled weather to Southeast Alaska this weekend. To
the west, a couple of modestly deep cyclones get forced northward
across the central/western Aleutians as surface high pressure
holds strong over the Mainland. Models indicate the ridge/block
may strengthen and slowly shift east with time as the upper low in
the Gulf slides farther south.
...Guidance/Uncertainty Assessment...
Good synoptic agreement amongst the latest 12z model guidance
lends to modest confidence that an Omega block will maintain
itself through the entire period. The greatest uncertainties lie
in the strength of the ridge and block, especially as you go later
in the period. This results in a rather chaotic array of surface
lows near the western Aleutians and also in the Gulf. The 12z CMC
is much stronger/farther west with the upper high by early next
week generally resulting in a more westward track of lows
south/west of the Aleutians. The GFS and UKMET are weaker with the
ridge, tending to bring systems farther east across the Aleutians
into the Bering. At this time, the 12z ECMWF seems to represent a
good middle ground between the weaker GFS and stronger CMC, and is
best in line with the ensemble means. In the Gulf, the GFS and
ECMWF have good agreement with each other on consolidating low
pressure until the very end of the period when the GFS pulls the
low quicker to the south towards the Northwest U.S..
The WPC progs for today used a majority deterministic blend with
more weighting towards the ECMWF days 4-6. After this, the CMC was
dropped (due to its exceptionally strong ridge/block) in favor of
more ensemble means to help mitigate the detail differences which
are hard to resolve at these longer time scales. Despite the
uncertainty, the overall forecast maintains good continuity with
yesterdays WPC progs as well.
...Weather/Hazard Highlights...
Arctic High pressure holding strong during the medium range period
will keep most of Mainland Alaska cold and dry. Meanwhile, storm
systems in the Gulf will translate to unsettled conditions along
the Southeast coast and Panhandle regions. Moderate to heavy
precipitation will shift slowly southward this weekend with
conditions tending to dry out by early next week as the upper low
moves farther south and some upper ridging tries to build in. A
decent pressure gradient along the coast may bring a period of
gusty winds as well to these areas. The eastern
Aleutians/Peninsula should stay quiet through much of the period
although a couple of storm systems to the west likely brings
renewed wet weather to the western and central Aleutians.
Temperatures across most of the state should start out below to
much below normal on Friday (except the Panhandle), though ease
with time as the upper ridge axis shifts slowly inland. By
Sunday-Monday, parts of the Western Alaska and North Slope regions
may see temperatures back to above normal, with the Panhandle
transitioning to much below normal.
Santorelli
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
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Thu-Fri, Jan 27-Jan 28.
- High winds across portions of the Alaska Panhandle and mainland
Alaska, Thu-Fri, Jan 27-Jan 28.
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