Firefighters have the proverbial snowball's chance of keeping blazes to a minimum in Utah as revelers prepare for illegal fireworks displays and crews try to cope with a dismal fire situation.

Flames ravaged more of Utah, and luxury homes were threatened by grass fires Friday as the mercury topped 100 in Salt Lake City for the sixth time this summer."It's just that it's so hot and dry," said Pete Hansen, Interagency Fire Center manager. "There's no moisture left in anything. We just don't have a chance."

Homes along Salt Lake County's east foothills were threatened as an eight-acre fire swept through scrub oak and brush. (See story, page B1.)

Sandy's fire stations were emptied, and federal firefighters joined crews from Salt Lake City and County, West Jordan, Midvale and West Valley to converge on the 30th East and 90th South area.

Firefighters began the assault on a 1,600-acre fire that broke out just before noon Friday near Salina, Sevier County. "It's in some grass and some wind and it's going," BLM fire dispatcher Warren Sorenson said.

Crews controlled a stubborn 475-acre blaze that began on July 11 in steep and rugged terrain about five miles west of Mona, Juab County, Sorenson said.

"This dry condition - we had a storm go through with lightning, and fires are popping up everywhere," he said, as another crew was dispatched to a reported fire near Little Sahara Recreation Area in Juab County.

Open fires now are forbidden in the Wasatch-Cache Forest in Salt Lake, Davis, Weber and Box Elder counties, Hansen said.

Campers and hikers may only use fires in designated, approved areas, Hansen said. "That means you can't go backpacking and start a fire" in any area that is not OK'd for fires.

A 280-acre fire that consumed desert shrubs and brush about 45 miles northwest of Cedar City was controlled at 6 p.m. Friday, and crews were being sent home, BLM dispatcher Eulail Pickering said.

"And we're going to be back there tomorrow rebuilding some fence that burned," she said.

Nearly 100 firefighters from Utah and Arizona had battled the flames in the desolate region that threatened no structures. An investigator was at the scene to determine how the man-caused fire began.

"It sounds like we have a good case, and we do have a suspect," Pickering said.

A helicopter pilot working the fire spotted a smaller blaze about seven miles away that crews were attempting to extinguish, she said. "We are getting quite a bit of lightning, and we had quite a bit of wind, so we're keeping careful control of it."

Flames up to 75 feet high were jumping from timber set ablaze in eastern Idaho's Targhee National Forest. Spokesman Jay Benson said the 150-acre fire began about 2 p.m. Friday, adding, "I'm sure it's going to head into Yellowstone."

A 350-acre range fire was sweeping through rugged terrain about 24 miles southeast of Twin Falls. No containment time was set.