Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
529 PM EST Sat Feb 22 2020
Valid 12Z Wed Feb 26 2020 - 12Z Sun Mar 01 2020
Spread among model guidance across Alaska and the North Pacific
during the extended forecast period continues to improve as
guidance gets a somewhat better handle on the evolving large scale
flow pattern over the upcoming week. Some of the specific details
of individual systems continue to be a bit murky, however. A
closed upper-level high should gradually weaken across the
northern Bering Sea by late in the week. This setup will allow for
increasing influence from arctic flow across much of mainland
Alaska, with another round of very cold temperatures seeming
likely. Farther south, a very active North Pacific storm track
will plague the Aleutians and the Gulf of Alaska with frequent low
pressure systems spaced 24-36 hours apart.
An area of low pressure is forecast to move northeast across the
western Gulf of Alaska on Wed. The GFS and UKMET were the
solutions most well-situated in the center of ensemble member
spread, and these solutions were weighted heavily during days 4-5.
By day 5 (Thu) another similar low pressure system is forecast to
enter the Gulf of Alaska, this one a bit farther east than the one
a day earlier. Both of these systems are expected to bring
potentially heavy precipitation to portions of southern mainland
Alaska and the Alaska Panhandle. Farther west, models show the
potential for a couple low pressure system to affect the Aleutians
later next week, one Thu night-Fri and another one (the stronger
of the two) Fri night-Sat. Due to high variability and spread
among deterministic guidance, leaned much closer to ensemble means
by later next week, along with some continued use of the GFS,
which was reasonably well-centered within the ensemble spread.
Ryan
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards 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