Travelers beware. The dense fog that hampered highway travel early Thursday in Cache Valley and some other areas is starting to move south.

William J. Alder, meteorologist in charge of the Salt Lake office of the National Weather Service at the Salt Lake International Airport, said a patch or two of fog developed Thursday morning along the Jordan River in Salt Lake County.An inversion, a common trend during the winter in the Salt Lake Valley, is expected to create gunky conditions as the week progresses. "It will be upside down air, with warm (conditions) aloft and cold on the surface. It's a good time to go skiing. It'll be in the 40s during the next days at the resorts," Alder said.

Temperatures in the Salt Lake Valley will be in the mid-to-upper 30s and probably only in the upper 20s to near 30 in Cache Valley.

The Utah Highway Patrol reported visibility at less than one-fourth mile throughout Cache valley early Thursday.

The fog was expected to begin thinning by midday Thursday. However, poor driving conditions are expected to redevelop Thursday evening, the National Weather Service reported.

Motorists traveling in Cache Valley were advised to allow extra time because of poor driving conditions.