NASHVILLE, Tenn. (AP) -- Below-freezing temperatures and snowfall are causing travel problems in the eastern half of Tennessee, even on some major routes.

The Tennessee Department of Transportation cautions of snowy and icy patches on Interstate 75 in Campbell County. There are also slippery roads on the eastern edge of the Cumberland Plateau and east of Nashville in Middle Tennessee.

Treacherous back roads caused a number of schools to call of classes for Friday, including those in Nashville.

A winter weather advisory was posted by the National Weather Service for some plateau counties as well as an area from south of Knoxville, northward through the Tri-Cities.

Dawn temperatures included 24 degrees in Knoxville, 30 degrees in Chattanooga and 23 degrees in Bristol. It was 18 degrees in Nashville and 25 in Memphis.