IDYLLWILD, CALIF. The threat of weekend thunderstorms could bring much-needed moisture to a huge wildfire in the Southern California mountains near Palm Springs.
Unfortunately it could also bring wind, lightning and other volatile conditions that could make a tough firefight even worse.
Combined with hot air on the ground, the unstable air could create a strong updraft that draws smoke high into the atmosphere, fire spokesman Capt. Mike Lindbery said.
If the smoke column rises too high, moisture at the top could freeze and the weight of the ice could cause the column to collapse, creating a powerful downdraft in all directions.
"We're very concerned because this is the condition in the past that has definitely caused big firestorms and the death of citizens and firefighters," Lindbery said.
The blaze in the San Jacinto Mountains had expanded to roughly 42 square miles and was 15 percent contained, U.S. Forest Service spokeswoman Kate Kramer said.
Susie Carlson of the San Bernardino National Forest told CBS News that more moisture would hopefully cool temperatures, "so it's not just a tinder box ready to go."
Thousands of people have been forced from their homes, as the town of Idyllwild is in serious danger from the flames.
Some communities on the eastern edge of the fire were reopened to residents, but about 5,600 homes remained under potential threat.
"When it first starts out, you don't think it will be that bad, and then all of a sudden the wind changes," resident B.J. Bricks told CBS News.
The fire was less than two miles from Idyllwild on its western flank. It was a similar distance from Palm Springs below on the desert floor, where an enormous plume of smoke could be seen, but the blaze was showing little threat of moving toward the much larger city.
Popular campgrounds, hiking trails and a 30-mile section of the Pacific Crest Trail, which runs from the Mexican border to Canada, remained closed.
Lt. Gov. Gavin Newsom, filling in for a vacationing Gov. Jerry Brown, declared a state of emergency for the area Friday night, freeing up more state funding and other resources to help with the protracted firefight that has already cost nearly $11 million.
Twenty-nine aircraft are currently battling the flames. For most of them, the historic Garner Ranch -- saved by fire crews in the early hours of the blaze -- is now the main helicopter staging area.
"We tell them if we are not here, open the gates and start spreading out," said Ted Johnson, a manager of the cattle ranch, "because they need a place to land that is private, and this is off the road far enough but close enough to their command center.
"Most of this area is pretty inaccessible to anything but aircraft," said Johnson, "so, yeah, they are basically what's saving a lot of the area and communities on this mountain from just being inundated completely."
The Garner family opened its land shortly after the fire started on Monday and -- like the flames -- the air traffic has only grown since then.
"It is beautiful, it's like it's choreographed, which it is," said Meg Garner. "They go in, they dip, they go up, they drop, they go around, they land, they refuel, they go, they dip ..."
Elsewhere, a wildfire broke out near the Grapevine section of Interstate 5, bringing an evacuation order for about two dozen homes and threatening the shutdown of the heavily-traveled stretch of highway north of Los Angeles.
Kern County Fire Department Engineer Anthony Romero says the fire started early Friday afternoon and by nightfall had burned 730 acres of brush, but some 400 firefighters had it 56 percent contained.
The California Highway Patrol says the fire may have been sparked by a roadside tractor-trailer.
In Wenatchee, Wash., a new wildfire on the north shore of Lake Wenatchee has destroyed four residences, likely vacation cabins.
RiverCom supervisor Jeremiah Johnson says no one was home in any of the structures that burned. He said the fire reported at about 6:30 p.m. Friday was 10 percent contained by 10 p.m. and had burned five or six acres. A helicopter was able to drop water on the flames.
The spokesman says the county sheriff's office declared a "get out now" evacuation notice in the area earlier in the evening but that advisory has been lowered.
In Oregon, officials say a wind-driven wildfire near the rural community of Williams has been 75 percent contained after racing across half a square mile and destroying one vacant home and several vehicles.
And in Nevada, firefighters reported major progress Friday in their battle against two lightning-caused wildfires in Elko County after one of them crept near a major natural gas pipeline.
The Wieland Fire near Tuscarora was 55 percent contained and the Cattle Guard Fire near Owyhee was 60 percent contained, U.S. Bureau of Land Management officials said.
In southern Nevada, the 19-day-old Carpenter 1 Fire on Mount Charleston, 25 miles northwest of Las Vegas, was 95 percent contained on Friday after blackening some 43.6 square miles.