Personal opinion from someone who grew up in Michigan...  I would say the idea of snow riding really only works if the ground freezes.  Even if the air is cold enough to keep the snow from melting right away the trail surface is still staying wet/saturated.  If a few bikes go out and ride probly not a big deal and i doubt we have many chomping at the bit around here for that snow ride.  If we get a snowfall after a sustained cold spell could be a good setup for the snow ride though.