I've traveled in an extreme thundersnow storm once. Lightning at night in the middle of a heavy snowstorm, on a steep mountain pass in a RV.... It was a bit intense. This was in Arizona and it was in the Airstream class A we were driving for the American Cancer Society and Megan had to stand over me with her hair blower on full blast because the defrosting system in the RV could not keep up with the fast developing ice crystals on the windshield.
Mark