Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
141 PM EST Sat Mar 02 2019
Valid 12Z Wed Mar 06 2019 - 12Z Sun Mar 10 2019
Upper ridging will only slowly trend eastward by the end of next
weekend into western Canada. This favors a continued stormy
pattern for the Bering Sea/Aleutians and western/southwestern
Alaska that will slowly trend across Southcentral and eventually
the Panhandle by the end of the period. The models/ensembles were
fairly well-clustered through the period and the 12Z GFS/00Z ECMWF
were close enough to their means and each other to utilize a
consensus blend for at least the first half of the forecast
period. Trended to just the ECMWF and especially its ensemble mean
for next Sat/Sun due to differences in track/timing in the Bering
Sea that spill eastward. The ECMWF ensemble mean has been
consistently south with that weekend storm compared to the GEFS
mean (which has trended southward toward its maximum spread). This
also seemed to fit the pattern evolution of retreating ridging.
A pair of deep systems will move through the Bering Sea/Aleutians
with strong winds (40-50kts) and a swath of rain/snow into western
then southern Alaska. The first will be Wed/Thu and the second
next Sat/Sun, each with a central pressure nearing 960mb.
Precipitation will focus along/ahead of the front initially into
Southcentral with southerly flow. Temperatures will trend colder
back toward climatological values in the interior as heights
lower.
Fracasso
WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can 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