Smoke from forest fires to the north rolled into the Rogue Valley, clotting the sky with a thick haze that likely won't lift until Sunday, National Weather Service meteorologists said.
Local fire crews got a handle on the remnants of Monday's big blazes that erupted on the outskirts of Medford and Ashland, although smoke occasionally may be seen drifting from these fires through the weekend, Oregon Department of Forestry District Forester Dan Thorpe said in a release announcing their containment Thursday at 6 p.m.
However, several large fires continue to burn in the Umpqua and Willamette national forests.
The Boze and Rainbow Creek fires in rugged terrain near Toketee in Douglas County had burned a combined 10,792 acres by Thursday, while farther north in Lane County, the Tumblebug complex had burned 9,228 acres. A lightning storm that hit Sept. 12 and 13 sparked those fires, and strong winds this week fanned them to rapid growth. Fire officials predicted they might not be contained until mid-October.
"They put up a lot of smoke," said Brett Lutz, a meteorologist at the National Weather Service's Medford office.
He noted that earlier this week the plume had shot into the upper levels of the atmosphere and been carried aloft all the way to Vancouver Island.
On Wednesday evening, however, the wind shifted, pushing the smoke south over the Cascades at Diamond Lake. It wafted into the Klamath Basin, then eventually slipped over the Siskiyous and into the southern part of Jackson County. As the temperatures rose Thursday, more smoke rolled in from the north over the Umpqua Divide, essentially bringing smoke from the same set of fires into the Rogue Valley from multiple directions, Lutz explained.
"Now we are really in the smoke," he said.
Lutz predicted that a slight shift in the winds expected overnight would limit the additional smoke coming in to the valley, but probably wouldn't clear much of it away. By this afternoon, northwest winds will return, delivering even more murky air. Winds out of the northwest will continue through Saturday.
While Lutz acknowledged it's difficult to predict how much smoke the fires will produce, then calculate which directions winds will push it and how long it will linger, the Oregon Department of Environmental Quality put out a warning Thursday afternoon that heavy smoke and haze were expected across Southern and Central Oregon.
"If you are bothered by smoke, stay inside," said DEQ air quality manager John Becker.
While air quality in Medford and Shady Cove hovered in the "moderate" range Thursday, it was listed as "unhealthy" at Crater Lake and in Klamath Falls.
Crater Lake National Park officials reported that visibility was poor in the park because of heavy smoke.
Becker speculated that much of the smoke was at higher altitudes, obscuring surrounding mountains with haze, but prevented by light breezes from settling to ground level where air-quality monitors and the breathing public are.
"Even moderate air quality is worse than what we're used to here," he said.
Lutz said that on Sunday west and southwest winds preceding a strong Pacific cold front should clear the Rogue Valley of smoke. However, the front will bring a dramatic change in the weather.
Although temperatures in Medford will remain in the 90s through the weekend, highs will drop to around 80 on Monday and 65 on Tuesday, Lutz said. Tuesday also will bring a chance of showers and even a possible dusting of snow at elevations above 6,000 feet, according to a special weather statement released Thursday on the approaching change in the weather.
Overnight lows on Tuesday will dip into the 20s east of the Cascades, but remain in the lower 40s on the west side of the mountains. High pressure will build again on Wednesday, warming things back up soon.
Reach reporter Anita Burke at 776-4485, or e-mail firstname.lastname@example.org.