EDMONTON -- Fog was so thick in some central Alberta communities Thursday morning it prompted Environment Canada to issue a special advisory Thursday morning.

Fog advisories were issued for Bonnyville, St. Paul, Lac La Biche, and Cold Lake region as well as Lloydminster, Wainwright, Vermillion and Provost.

"Travel is expected to be hazardous due to reduced visibility in some locations. If visibility is reduced while driving, slow down, watch for tail lights ahead and be prepared to stop," the advisory read.

Environment Canada said areas of dense fog would persist until late morning. 

The fog advisories were lifted as of 11 a.m.