I'm with glc -- 40 can be a problem, too.
Early last February, a big snowstorm hit northern Arizona. We left Flagstaff heading south on I-17 the morning after that storm. We had to go VERY slowly for about the first 30 miles or so, until we finally drove out of the snow just south of Schnebly Hill Drive exit. Both I-17 and I-40 had been closed during the night for several hours.
Donna
