Update: The current dense fog advisory for Central Pa. will be expiring at 11 a.m.

The advisory had been issued for Northern Clinton, Northern Centre, Southern Centre, Northern Lycoming, Southern Clinton and Southern Lycoming as well as Warren, McKean, Potter, Elk, Cameron, Clearfield, Tioga, Sullivan, Union, Snyder, Montour, Northumberland, Columbia, Dauphin, Schuylkill, Lebanon, York and Lancaster counties.

"Visibility will gradually improve through the afternoon. Expect lingering visibility reductions on ridgetops through Friday morning," states the National Weather Service.