Thanks to a blizzard that dumped a ton of snow on the metro area and left roads slick with ice, not everyone who’d purchased a ticket for Ben Vereen’s Feb. 2 appearance at Newman Center for the Performing Arts showed up. But those who did were in for a treat. Vereen, who’d just been inducted into the Theatre Hall of Fame, stayed on stage for 2 1/2 hours. His performance was a preview of the autobiographical production “Tenacity,” which will open on Broadway in July. In addition to Vereen, the show also included numbers by the S.T.A.R.S. Trio and Colorado Ballet.