COLUMBIA, S.C. (AP) -- Forecasters are warning of the potential for slick roads Friday because temperatures were expected to drop through the night in South Carolina's Upstate.

The cautions come after sleet and freezing rain fell across parts of the state Thursday, causing hundreds of wrecks -- but no reported fatalities -- in northern areas.

The National Weather Service issued a winter weather advisory until 9 a.m. Friday for the Anderson, Greenville, Spartanburg, Gaffney and Rock Hill areas.

A warmup is coming: Temperatures across the state are expected to get into the 50s Friday.

The weather service said rain and sleet created some slick spots in the Florence and Myrtle Beach areas. Schools in Anderson, Greenville, Oconee, Pickens and Spartanburg counties were either closed or on delayed starts Thursday.