"We're ... bracing for a busy day. ... It has been hard for our crews to find a safe place to set up and begin working," Howell said.
The fire was 5 percent contained as of Wednesday night.
Nearing containment on Wednesday was the 1,592-acre Wildflower Fire in the Simpson Mountains of Tooele County.
Fire Information Officer Teresa Rigby said that fire, burning in sagebrush, pinyon and juniper, was 75 percent contained. Crews anticipated completing lines around the flames sometime on Thursday.
However, with temperatures still at or above 100 degrees in forecasts through the remainder of the week, continuing tinder-dry conditions and thunderstorms expected in some mountain locales, firefighters warily watched the horizons for fresh smoke.
The 5,200-acre Antelope Fire in Millard County's Cove Fort area and the 23-acre Flat Canyon Fire burning 8 miles north of Fayette in Sanpete County were fully contained Wednesday night.