Really good AFD from my office.
With cold air firmly in place, the stage is set for our next round
of wintry weather. Northwesterly flow aloft will allow for a clipper
system to move southeast over the region. Models suggest the ridge
over the West may be a bit stronger, pushing our storm system more
northward into southern Alberta. This stronger ridging to our west
may also allow the shortwave to dig further south as it moves over
the Plains Wednesday night/Thursday morning. A deeper diving low
would lead to a stronger system overall. Similar to yesterday,
models that show a stronger mid-level shortwave trough, create more
snow and take that snow further east. This is the case for the NAM,
ECMWF and the Canadian. The GFS is fairly similar to its 12Z run
from yesterday, depicting a weaker mid-level wave and weakening the
snow as it moves further east. Given the agreement of the NAM,
ECMWF, and Canadian, confidence is increasing in light snow moving
through the area Wednesday night through Thursday morning. Forecast
soundings show temperatures entirely below freezing. With cloud ice
present, precipitation type will be all snow. But forecast soundings
do show a substantial dry layer that will have to saturate before
snow begins. This will likely occur late Wednesday evening into the
overnight hours. Snow ratios also look slightly drier/higher than
normal given the cold air in place. Factoring that all in, looks
like snow amounts up to 2 inches will occur across the area, with
some locally higher amounts likely. The main area of uncertainty is
if and where any narrower band of snow may develop and the potential
for a narrow band of higher accumulations. Given decent
frontogenetic forcing, this looks like a real possibility. The NAM
depicts a progressive frontogenetic band, most notable at 700mb,
from southeast NE through northeast KS and through the forecast area
north of the Missouri River. The Canadian shows this band further
south and the ECMWF is just too coarse to depict that fine of a
feature. This possible mesoscale feature will be handled better
when the event gets into the time frame of higher resolution
models.