Whether the latest rash of lightning strikes sweeping through the Cascade foothills and mountains in Lane County will cause significant wildfires won’t become clear for a number of days.

About a dozen small lightning fires have already been reported in the Middle Fork Ranger District of the Springfield-based Willamette National Forest.The National Weather Service predicts a chance of thunderstorms through the weekend and into early next week from the foothills to the Cascades and beyond.

It often takes four to six days after lightning strikes and small fires for it to become evident “which ones are real fires and which ones go out on their own,” said Willamette National Forest spokeswoman Jude McHugh.

Fire growth Friday was minimal, although a few new small fires were located, McHugh said. “Better mapping for the largest fires in Staley Creek indicates that approximately 70 acres are within the burn area, however not all of those acres have burned completely,” she said. So far, the agency is using local staff to scout out and fight the fires.

The spate of fires are all about 25 miles southeast of Oakridge, in an area of the boundary between the Willamette and Roseburg-based Umpqua national forests.

“They are entirely contained in the national forest system,” McHugh said. “There are no houses, no people, no private lands at risk.”

The fires are “in steep country, with old growth trees, a lot of cliffs,” she said.

Residents of Oakridge will see a fair number of helicopters in the air over the next several days, and depending on weather conditions and other factors, perhaps for a few weeks, McHugh said.

Further east, at Willamette Pass, the weather service forecasts a chance of thunderstorms every day from today through Monday afternoon.

One new fire apiece has also been reported in Willamette National Forest’s McKenzie River and Detriot ranger districts.

Forest Service District Ranger Darren Cross asked that visitors be extra careful with driving in the forest and with campfires. “We’ve got our hands full right now and the best way everyone can help is by taking it easy out there and being sure any fire you have is dead out,” he said.

A spokesperson for the Umpqua National Forest said Friday morning it has confirmed 11 fires on its terrain, totalling about two acres.

The agency has sent crews to fight the smoldering fires.

Meanwhile, in southern Oregon, the Oregon Gulch fire has burned buildings but there are no reports of injuries from a fire that was touched off by lightning along the Oregon-California border, a fire spokesman told the Associated Press. Some ranch families east of Ashland have been evacuated.

Air crews over the fire reported damage to multiple outbuildings such as barns, sheds and other uninhabited structures, the news service reported.

There was no estimate of how many people fled. “It’s not a whole lot of people because not a whole lot of people live out there,” said Brian Ballou of the Oregon Department of Forestry.

Gov. John Kitzhaber invoked the state’s Emergency Conflagration Act on Friday, requiring the state police and fire marshal to mobilize equipment, firefighters and other personnel from around the state.

The Oregon Gulch fire doubled from Thursday night to Friday, about 17 square miles, or a little more than 11,000 acres.

It erupted in the Cascade-Siskiyou National Monument on Thursday amid swirling winds and dry conditions.

Ballou said Friday that the wind died down a bit overnight, and firefighters made progress on containment lines.

— Business editor Ilene Aleshire contributed to this story.