Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
354 PM EST Wed Dec 27 2023
Valid 12Z Sun Dec 31 2023 - 12Z Thu Jan 04 2024
...Wet pattern for the southern fringes of Alaska...
...Windy conditions expected in pockets around the state,
especially early to mid next week, as a large and deep storm moves
into the region...
...Overview/Guidance Evaluation/Preferences...
A deep layer cyclone is expected to waver between the southern
Bering Sea and Aleutians this period, which gets significantly
reinforced by a large and strong cyclone early to mid next week.
The 12z GFS was a slight outlier when compared to the other
guidance, so didn't weight it as much as usual. Most of the grids
were weighted towards the agreeable 12z Canadian, 12z ECMWF, 12z
NAEFS mean, 00z ECMWF ensemble mean with many grids using an NBM
starting point. This should deal with small scale issues, such as
the smaller low approaching the AK Peninsula Sunday night and the
position of the upcoming large and deep cyclone late in the period.
...Weather/Hazards Highlights...
The expected flow pattern leads to some confidence in multiple
inches of precipitation (coastal rains, with snow at higher
elevations/inland) near south-central AK, particularly late in the
period as the large and deep cyclone moves in from the west. Gale
to storm-force winds are expected offshore the North Slope,
Kotzebue Sound, Norton Sound, the Aleutians, favored locations in
southern AK, with hurricane-force winds south of the Aleutians and
potentially channeling between Kodiak Island and Kenai Peninsula
from Tuesday into next Wednesday. This will also include
wave/swell threats. Meanwhile, a significant warming trend will
be happening across western and southern Alaska through the
period, with cold air harder to scour out of the North Slope and
the eastern interior due to how far south the cyclone track/cold
low is expected to be in the southern Bering Sea. Temperatures
across western and southern Alaska should warm to well above
normal.
Roth
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