A worker clears snow from the front of the Mercer County Courthouse this morning. The Ohio National Weather Service issued a heavy snow advisory for Mercer and Auglaize counties through 7 a.m. Wednesday, with a total of 8 to 12 inches predicted. Mercer County is under a Level One snow emergency (a warning about drifting snow and icy roads) as of late this morning. All residents are reminded to keep vehicles off the streets so plows can clear roadways.