Ideal conditions have set up for heavy bands of lake effect snow on southeast and eastern shores of the Great Lakes. Very chilly air moving over the relatively milder water picks up moisture and deposits it as snow on the landscape downwind.
In the olden days, forecsters would use cook book rules to try and determine the snowfall accumulation from lake effect snows. Often there will be a wide range of snowfall potential because a slight shift in winds will reroute the snowbands. Computer models have been tweaked to forecast lake effect snow.
It is not uncommon for some places to be observing sunshine and within miles other locations, close to the lake, have near zero visibility with heavy snow falling.