Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
354 PM EDT Sat Jun 22 2019
Valid 12Z Wed Jun 26 2019 - 12Z Sun Jun 30 2019
A relatively benign weather pattern will persist across Alaska
during the medium range, with a persistent upper-level ridge axis
extending from the North Pacific across western mainland Alaska
north to the Arctic. Shortwave energy will traverse a mean upper
trough centered across the western Bering Sea/western Aleutians,
with a couple waves of low pressure will move through the mean
trough, with energy splitting as it encounters the ridge, either
deflecting north back into the mean Bering trough or east, well
south of Alaska across the north Pacific. Meanwhile, on the
eastern periphery of the upper ridge, weakening arctic cold fronts
should move southward, bringing a return to near or slightly below
average temperatures to the North Slope and eastern portions of
the Interior, along with the potential for isolated to scattered
showers.
The WPC forecast was based on a blend of the GFS and ECMWF during
days 4-5, with more weight placed on the GFS due to continued
better run-to-run consistency relative to the ECMWF. Increasing
weight was placed on ECENS and GEFS ensemble means from day 6
onward to account for increasing spread, including differences in
how solutions handle the upper ridge and the track of low pressure
systems traversing the mean upper trough.
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