Clark Fire crews set burns to gain an edge on blaze.

Byline: Greg Bolt The Register-Guard

Firefighters continue to torch a safety zone around the Clark Fire in an effort to lasso the 2,500-acre blaze and keep it from jumping key ridge-lines in the face of threatening weather.

Crews were keeping a wary eye out for the possibility of evening thunderstorms Monday and today. They hope the burnouts along roads and fire lines on the north, east and west flanks will open enough of a gap between the flames and unburned forest to hold the fire even if stormy weather kicks up stronger winds.

The effort is seen as a key to getting the upper hand on what has been a stubborn and hard-to-fight blaze.

"It's a sensitive point of the fire," fire information officer Mary Lee Sayre said. "This needs to go well."

Hot, dry weather is expected again today along with the threat of thunderstorms, particularly higher in the Cascades. The National Weather Service issued a red flag warning Monday for possible dry lightning in the mountains and strong, erratic winds at lower elevations through this evening.

The warning cautioned that the combination of high temperatures, low humidity and very dry conditions will create a recipe for extreme fire behavior when mixed with the possibility of lightning and strong winds.

Crews and equipment from the Clark Fire will be responsible for the initial attack on any new fires that break out within a 140,000-acre area around them.

The fire continues to burn the hottest along its northeast boundary. Successful burnouts Sunday evening widened four miles of fire line in that area and crews moved down the eastern edge Monday.

If things go well, Sayre said incident managers could start talking about an estimate of containing the fire toward the end of the week. The burnouts could push the total acreage burned in the blaze to 3,000 to 4,000 acres, she said.

But the burnouts are necessary to provide firefighters with adequate safety zones should the flames make a run up steep canyons thick with trees and brush. Fire information officer Gregg Thayer said that could send embers over the ridge, where the fire could again blow out of control.

Once burnouts are completed along the fire line, helicopters will be called in to start additional burnouts deeper in the fire zone in areas that are inaccessible to ground crews.

"If we didn't burn it out, the fire would burn it out," Thayer said of the control effort. "We're meeting the fire on our terms instead of meeting it on the fire's terms."

The fire is burning in old growth and second growth trees and brush in rugged terrain in the Fall Creek drainage east of Lowell and is now 15 percent contained. About 1,100 people are assigned to the fire along with dozens of firetrucks and six helicopters.

Campgrounds and roads in the Fall Creek drainage remain closed with no estimate for reopening.

While the north end of the fire continues to burn, the south end is under control and is being mopped up, Sayre said. The area south of Forest Road 18 is down to a few hot spots, and firefighters are moving the mop-up operation to interior portions of the fire zone as it becomes safe to do so.

Willamette Valley residents continue to experience smoky conditions as a nighttime inversion layer traps smoke near the ground and funnels it downhill into the valley, only to be blown out again as afternoon winds develop and the inversion lifts.

Field burning was not allowed Monday due to winds that would have blown more smoke into populated areas.