Eleven flights had to be diverted from the Salt Lake City International Airport early Friday because of low visibility caused by fog, according to an airport spokeswoman.
All other early morning arrivals and departures at the airport were delayed because of the weather, according to Barbara Gann.
Gann added that the fog had cleared up by late morning and operations were back to normal.
The National Weather Service issued a hazardous weather outlook Friday that called for patchy, dense fog under the strong valley inversions through north west and central Utah.
Foggy conditions are expected to resume Friday night. The inversions are expected to remain through Tuesday of next week, but a Pacific storm system could bring some snow and "a brief period of improved air quality late next week," the outlook predicts.