Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
200 PM EST Mon Mar 04 2019
Valid 12Z Fri Mar 08 2019 - 12Z Tue Mar 12 2019
Despite the stark change in the upper pattern across Alaska by
next week, the models/ensembles remain in good agreement through
the period. A blend of the GFS/ECMWF with their ensemble means
(about 60/40 deterministic/ensemble weighting) served as a good
starting point given the expected track/depth shifts in the models
from cycle to cycle. ECMWF has generally been a bit more
consistent but the GFS was certainly within the tight cluster of
solutions.
Lead deep system out of the short range will split and
weaken/dissipate by Saturday as another deep system (central
pressure perhaps below 960mb and wind 40-50kts) that will finally
be the catalyst that dislodges the seemingly omnipresent upper
ridging over the 49th state the past few weeks. This will bring in
colder air to the interior/North Slope but milder air to the
Panhandle which will lose its cold easterly flow for onshore flow
and much more rain/snow. Ensembles and certainly the deterministic
models pick up on another system out of the central North Pacific
next Sunday/Monday that may lift into the Gulf next Tuesday or so
as troughing settles along 160W.
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