Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
428 PM EDT Wed May 02 2018

Valid 12Z Sun May 06 2018 - 12Z Thu May 10 2018

Ridging will build across NW Canada into eastern Alaska next week
as an upper low settles into the Bering Sea and becomes blocked
from moving eastward through the Gulf of Alaska. The
models/ensembles remain in excellent agreement on the longwave
pattern and a blend of the 12Z GFS / 00Z ECMWF (and some 00Z
Canadian) with increased weight of the 06Z GEFS and 00Z ECMWF
ensemble means offered a good starting point for much of the
forecast. Trend has been toward a track along or just south of the
Aleutians with the next system Sun-Tue that should take its triple
point low toward the Gulf but should likely get sheared apart as
it encounters ridging to the east next Wed/Thu. Trailing shortwave
rotating around the Bering circulation may realize a surface front
well south of the Aleutians that may try to lift northeastward
toward the Gulf next Wed/Thu (per the 12Z GFS) but this may be
overdone at face value given the strength of the upper ridge.

Near to below average temperatures are expected over most of the
state for the start of next week, but eastern/interior areas will
see a trend toward above average temperatures by the middle of
next week as ridging pokes in from the southeast.
Rainfall/mountain snowfall will be focused over coastal
southcentral areas into the Panhandle where max temperatures will
be below average. Rain and mountain snow will exit the
interior/Panhandle by Monday as the stationary boundary dissipates
and ahead of the Bering system which will bring in another round
of modest precipitation from the Aleutians to Kodiak.


Fracasso


WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can be found at:

http://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html