Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
602 PM EST Fri Feb 26 2021
Valid 12Z Tue Mar 02 2021 - 12Z Sat Mar 06 2021
...Overview and Guidance/Uncertainty Assessment...
Upper pattern will transition from defined/semi-amplified to more
zonal by the end of next week, suggesting decreased confidence in
system timing/track/amplitude. The models/ensembles showed signs
of this lower predictability pattern with a bit less agreement
than in the past few days. However, overall agreement remained
good to start and a mostly deterministic blend sufficed as a
starting point. Gave a bit more weight to the GFS/ECMWF which
offered better agreement with the ensemble means (GEFS and ECMWF
EPS) than did the UKMET and Canadian. After the lead system moves
through the Panhandle early Tue, pattern will trend toward weaker
systems that move quickly through the flow or try to develop
around the backside of the Gulf upper trough. Focus for upper
troughing will turn to eastern Asia/northeastern Russia as upper
heights build over the North Central Pacific, aiding in a
quickening N Pac jet. Trended toward a majority ensemble weighting
by the end of next week as this increasingly zonal pattern
develops, due to a decrease in model agreement (though the
ensemble means were still in good agreement overall).
...Weather/Hazards Highlights...
Gulf system on Tue will bring rain/snow to the region and turn
showery for the end of the week as the upper trough digs
into/through the Gulf. Light to perhaps locally modest rain/snow
is likely for the Aleutians later in the week in response to the
far NW Bering system and frontal passage. This may spread some
light snow into southwestern areas as the weakenig system moves
into the Gulf. Temperatures will generally be below normal over
much of the state next week (especially Tue-Wed), focused over the
western/southwestern portion of the state as the upper low moves
through. Some moderation is forecast as ridging moves into the
area, by the end of the week, limiting the cold air to much of the
Interior as well as the Panhandle.
Fracasso
Hazards:
- High winds across portions of mainland Alaska and the Aleutians,
Mon, Mar 1.
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