Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
248 PM EST Thu Nov 08 2018

Valid 12Z Mon Nov 12 2018 - 12Z Fri Nov 16 2018

Ensembles show reasonable agreement through the period with the
slow movement of the upper low eastward along the eastern
Aleutians to the Gulf of Alaska. Though there remains
intra-ensemble system clustering the overlap areas usually prove
to be a good starting point as a first pass. With the 12Z GFS and
00Z ECMWF forming the near bookends of the spread due to
individual system timing/strength/track, opted to rely on the
ensemble mean consensus for roughly 50% of the blend which
maintained good continuity from the previous forecast albeit a bit
slower with the second system later next week. This seems to fit
the trend of having the stubborn ridging over the west coast of
North America (though sometimes squashed) at least slow down the
eastward progression of embedded systems.

Rainfall potential is on the high side for Southcentral
(especially the southern Kenai peninsula but also eastward toward
the Panhandle) with a strong southerly influx of moisture ahead of
the first system early next week. In-house QPF guidance and NBM
QPF show 5-10 inches over a few day period. The east-west extent
is in question due to the sfc wave modulation of the moisture
plume as well as uncertain sustainability over a focused area.
Nevertheless, heavy coastal rain and elevation snow is probable.
Temperatures will trend colder in time over most of the state,
especially the interior, from above average to below average.

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