HELENA, Mont. - Wildfires have burned together in southwestern Montana's Bitterroot Valley and along the Continental Divide, forming the nation's largest fire group, a federal official said Saturday.
And elsewhere in the West, potential evacuation plans were ready for two small towns threatened by a blaze in Washington.
The Bitterroot Valley fire and the Mussigbrod fires in the Big Hole River drainage covered an estimated 247,000 acres, said E. Lynn Burkett of the National Interagency Fire Center in Boise, Idaho.
''That is the biggest fire complex in the region. It's a lot, and with a fire of that size and magnitude it will take a significant fall weather event to stop it - like rain or snow,'' she said.
But instead of rain or snow, a ''red flag'' alert was posted Saturday, warning Montana and surrounding states of scattered dry thunderstorms - with lightning, gusty wind and low humidity - through the weekend as a cold front rolled through, she said.
Both the Bitterroot Valley and Mussigbrod fires were started by lightning on July 31. Since then,the Bitterroot fires had destroyed about 70 dwellings.
The Interagency Fire Center on Saturday reported 82 fires nationally on Saturday, most of them in the West. They had spread across 1.5 million acres and more than 13,000 firefighters were assigned to battle them.
Montana had 25 fires on nearly 660,000 acres,
Wind had already started gusting above 30 mph early Saturday in south-central Washington, as National Guardsmen joined firefighters trying to keep a 110,000-acre blaze away from two small towns.
At midday Saturday, a ridge stood between the Washington fire and Prosser, a town of about 5,000 people.
''We really don't want it to pop over that ridge top,'' said fire information officer Cynthia Reichelt.
An evacuation plan had been prepared for Prosser and nearby Mabton, which has about 1,700 people.
''We're prepared for that, but we haven't had to go there yet and hopefully we won't have to,'' Reichelt said.
Idaho had 26 major fires covering 700,000 acres, including the nation's biggest single fire, which had blackened 180,000 acres of the Salmon-Challis National Forest near the Montana state line.
Fire officials announced that more of the Salmon-Challis would be closed Monday, meaning about half of the 5-million-acre forest would be off limits to hunters, fishermen and campers.
One of the Montana fires was an 84,000-acre blaze near Townsend, between Helena and Bozeman, that over the past couple of weeks has shut down a major power line and separated ranchers from their cattle herds.
A deluge of 52,000 gallons of retardant nipped flare-ups of that fire on Friday, but information officer Dan Kincaid said the situation could become ''dicey'' if the wind hit 35 mph as predicted during the weekend.
The weather was going to make firefighting doubly difficult and ''all fire lines are bracing'' for the passing weather front, said Ed Bloedel, a Bitterroot National Forest official.
''We're not putting any crews in where those conditions may get them in trouble,'' he said.
On the Net:
Interagency Fire Center: http://www.nifc.gov