Sunday night and monday: next in the hit parade is a significant
snowstorm with the potential for accumulations of 6+ inches and
strong winds. As of now the models are suggesting the heaviest snow
falling along and north of I-80 but this will depend on the track of
the surface low and phasing. Temperatures will moderate with highs
in the teens north and 20s south.
Tuesday through wednesday: in the wake of this system (and the much
deeper snowpack that will be in place) this will set the stage for
brutally cold Arctic airmass to plunge southward into the Midwest.
If the European model (ecmwf) is correct this may be historic (record) cold as the
polar vortex drops into the Great Lakes region. 850 mb temperatures
drop to an incredible -34 to -36c down to northern IL!. the GFS is
not as brutal keeping the vortex up towards James Bay with 850 mb
temps only to -26c. Either way you look at it this will be extreme
cold with record temperatures possible. The grids indicate lows well
below zero early Thursday morning, as low as 20 below in our north.
However, this is heavily weighted on the GFS model, so if the European model (ecmwf)
is correct it will be much colder than currently forecast, possibly
to 30 below zero or colder ambient temperature!