Visitor volume showed a small uptick in January, despite a calendar quirk that made for a tough comparison against 2011 totals, the Las Vegas Convention and Visitors Authority said. The LVCVA reported 3.15 million visitors to Southern Nevada in January, 0.9 percent ahead of 3.13 million in 2011. But 2011’s calendar had the benefit of five full weekend dates while January 2012 had only four Saturdays.