NASHVILLE, Tenn.—A winter storm blanketed parts of the South with snow, freezing rain and sleet Thursday, tying up roads in Tennessee and Kentucky as the system tracked a path through Appalachia toward the Mid-Atlantic and Northeast. Nashville saw 6.3 inches of snowfall on Thursday, shattering the city’s previous Jan. 6 record of 4 inches that had stood since 1977, the National Weather Service said. Freezing rain and sleet coated areas around the Tennessee-Alabama state border, said Scott Unger, a meteorologist for the service in Nashville. Authorities urged people to travel only when necessary, as Metro Nashville Police reported accidents and other driving woes that snarled and slowed several roads. Police in the city reported dozens of wrecks on the road by the early afternoon. A bevy of crashes and other issues bottlenecked drivers on multiple interstates in the region. Along the Kentucky border, authorities in Montgomery County, Tennessee, were dealing …