RAPID CITY, SD (KELO) -- Snow has been piling up in the Black Hills during a weekend winter storm that's creating difficult driving conditions Sunday morning. The Pennington County Sheriff's Office posted a photo Saturday night showing what drivers were facing in the Rapid City area. Future SF population growth could be up, not out They reported Interstate 90 was extremely slick in spots with white-out conditions in some places. They're urging drivers to slow down and use caution on the roads. Some roads are closed in the Northern Black Hills.