Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
754 PM EDT Thu Oct 20 2022
Valid 12Z Mon Oct 24 2022 - 12Z Fri Oct 28 2022
...A Bering Sea low will bring a threat of high winds and waves to
the Aleutians early to middle of next week with heavy snow
possible for inland western Alaska midweek...
...Overview and Guidance/Predictability Assessment and
Weather/Hazards Highlights...
The extended period will begin with a deepening cyclone entering
the western portion of the Bering Sea. The ECMWF has been the
fastest among the guidance while the GFS and CMC keep the cyclone
center farther to the west over the Bering Sea. The ensemble
means also indicate this tendency. The system is expected to
spread high winds and waves across the Aleutians into the Alaska
Peninsula especially on the back side of the system with very
gusty winds by midweek. Precipitation amounts across the
Aleutians are not expected to be excessive. However, by the time
the system reaches the West Coast by around next Wednesday, deep
south to southwesterly flow from the Pacific overrunning trapped
inland cold air is forecast to bring a threat of heavy snow across
the inland sections of western Alaska midweek.
Toward the end of next week, ensemble means show decent agreement
with the main cyclone center sliding into the Gulf of Alaska. The
GEFS again favor a slower evolution into this overall pattern.
Heavy precipitation is possible late next week from the southern
coast to the Panhandle. The faster ECMWF and CMC favor the
heaviest precipitation to focus farther down across the Panhandle.
The suite of Alaska products was based on 40% 12Z ECMWF/00Z/12Z EC
mean, 40% from the 12Z GFS/GEFS, and 20% from the 12Z CMC/CMC
mean. The faster EC/CMC solution is favored toward the end of the
forecast period, in which mostly a comprise of the ensemble means
is used. This blend maintains reasonably good continuity on the
mass fields with the previous forecast package. On the other
hand, the QPF amounts have increased along the southern periphery
of Alaska.
Kong
Hazards:
- High winds across portions of mainland Alaska and the Aleutians,
Mon-Wed, Oct 24-Oct 26.
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