Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
527 PM EDT Sat May 30 2020
Valid 12Z Wed Jun 03 2020 - 12Z Sun Jun 07 2020
...Overview and Weather Hazards/Threats...
A mid/upper-level ridge centered across the Beaufort Sea/Arctic
Ocean is expected to meander over the Beaufort/Arctic and only
slowly weaken by next weekend. This favors above average
temperatures for western mainland Alaska into parts of the
Interior to start the period but will trend cooler with time. High
temperatures in the 70s for some Interior locations will be about
5 to 15 deg F above average and cooler than the short term. To the
south, an upper low south of Kodiak will slowly move eastward then
southeastward to be replaced by another from northeastern Russia
which will bring cooler temperatures to western areas. Weak
mid-level flow near the Alaska Range to the Tanana Valley will
promote scattered showers and some convection through the period,
some of which could be locally modest in amounts. Additional light
rainfall will be possible over Southeastern areas especially on
Wednesday as a surface trough lingers over the Gulf in the wake of
a frontal passage in the short term. By next weekend, a system
over the central North Pacific will creep northeastward but likely
remain well south of the area.
...Guidance/Predictability Assessment...
Latest 12Z guidance mostly aligned with the track of the old
parent low through the southern Gulf and then southeastward,
though the GFS was just to the southeast of the better consensus
of the ECMWF/UKMET/Canadian. The models/ensembles showed good
agreement to the north with the nearly stationary upper high that
may maintain itself into next weekend. To the west, better
agreement existed with a weak upper low out of northeastern Russia
that should maintain itself across the Bering, but may not
manifest itself much down to the surface. Consensus approach was
adequate there. Farther south, models agreed on the track/speed of
the north central Pacific system until later in the week when the
GFS/Canadian left the better consensus of the ECMWF and part of
each ensemble system (GEFS a bit farther west like the GFS and
ECMWF ensemble mean a bit farther east like the ECMWF). Preferred
to stay near the ECMWF for this system which should continue on a
more easterly rather than northerly trajectory, but confidence was
no better than average.
Fracasso
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