Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
659 PM EST Thu Feb 23 2023
Valid 12Z Mon Feb 27 2023 - 12Z Fri Mar 03 2023
...Threat of heavy precipitation from southwestern Alaska to the
Panhandle early to middle of next week...
...Pattern Overview, Model Guidance/Predictability Assessment and
Weather/Hazard Highlights...
An occluding cyclone forecast to approach southwestern Alaska
early next week will likely be the main system of concern during
the medium-range period. This system will likely bring heavy
precipitation from west to east across the southwestern and
southern periphery of Alaska from late Monday onward. Potential
exists for moderate to locally heavy snow to impact farther inland
across interior sections of southwestern Alaska later on Monday
into Tuesday. This scenario is best supported by the ECMWF which
continues to bring a stronger cyclone across Bering Sea and with
the northern-most track among the guidance. The deterministic
GFS, on the other hand, has continued to indicate a more southern
track but recent runs have subtly nudged the track further and
further north. Meanwhile, the GEFS mean track has been much
farther north than the deterministic GFS, and is in much better
agreement with the ECMWF, CMC, and their ensemble means. In
addition, the GEFS has been nudging the low track farther north as
well. Therefore, inclusion of the deterministic GFS is minimized
in today's WPC blend, especially for the early part of next week.
The WPC fronts and PMSL forecasts were derived mainly from the 00Z
& 12Z ECMWF and the EC mean, the 12Z GEFS, as well as smaller
contributions from the 12Z GFS, 12Z CMC and CMC mean. The results
are quite compatible with WPC continuity.
The medium-range period should begin with relatively quiet weather
next Monday with below to much below normal temperatures across
west-central Alaska. However, precipitation ahead of the
aforementioned low pressure system is forecast to reach the
southwestern Alaska late Monday/Tuesday. Precipitation near the
coast will have the highest chance to be in the form of a wintry
mix. Farther inland however, potential exists for moderate to
locally heavy snow to spread into interior sections of
southwestern Alaska later on Monday into Tuesday depending on how
far north the system will take. Thereafter, models are in
relatively good agreement for heavy precipitation to spread from
west to east across the southern coast to all of the Panhandle
through next Thursday as a triple-point low develops near the
southern coast by about next Wednesday. By next Friday, models
agree that a drying trend should set in as the coastal system
degenerates.
Kong
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Tue-Wed, Feb 28-Mar 1.
- Heavy snow across portions of mainland Alaska, Tue-Wed, Feb
28-Mar 1.
- Much below normal temperatures across portions of mainland
Alaska, Sun-Mon, Feb 26-Feb 27.
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