Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
757 PM EDT Tue Apr 04 2023
Valid 12Z Sat Apr 08 2023 - 12Z Wed Apr 12 2023
...Overview with Guidance Evaluation/Predictability Assessment and
Weather/Hazard Highlights...
A cold upper low from the Arctic Ocean will likely meander over
the western portion of mainland Alaska through the medium-range
period under a rather blocky upper-level pattern across the
Arctic. Model solutions are in rather good agreement on this
scenario with some tendency for the upper low to slide
southeastward across southwestern Alaska by early next week. Dry
but much colder than normal conditions can be expected for western
and southwestern Alaska through the medium-range period
Temperatures may begin to recover slowly early next week if the
upper low erodes some, but with increasing spread in this scenario
in the longer range forecasts. Meanwhile, the southern coastal
and mountainous sections of Alaska will see waves of moisture
arriving from the Pacific, with the Panhandle likely experiencing
the peak of the moisture surge Sunday into Monday as a cyclone
edges toward the Gulf of Alaska from the south. Excessive
precipitation is not expected under this modestly strong moisture
plume. The next cyclone of concern appears to be moving into the
western Bering Sea by about next Tuesday to Wednesday as the lead
frontal system is forecast to pass through the Aleutians at a
relatively quick pace. Model ensemble means are in good agreement
on this system for a Day 7-8 forecast while the deterministic
solutions did not diverge too badly either. The speed of the
front will appear to limit the threat of heavy precipitation
across the Aleutians although some high winds cannot be ruled out.
The WPC Alaskan forecast package was based on a blend of 40% from
the 12Z EC and EC mean, 40% from the 12Z GFS and GEFS, and 20% CMC
and CMC mean for Days 4-6, followed by a slightly increased
weights given to the ensemble means from Day 6 through Day
8.
Kong
Hazards:
- Much below normal temperatures across portions of mainland
Alaska, Fri-Tue, Apr 7-Apr 11.
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