Critical fire weather possible this week
A high pressure ridge over east Oregon and the Great Basin is expected to push dry, downslope winds out of the north and east over the Stanislaus National Forest in portions of Tuolumne and Calaveras counties beginning Monday night through Wednesday morning.
“The winds will be coming down the west slope Sierra,” Eric Kurth, a National Weather Service meteorologist in Sacramento, said Monday in a phone interview.
“It’s a dry wind, and it tends to get warmer and drier,” he said. “You’ve got the drying and you’ve got the wind, and the fuels. The things that can burn are very dry right now and we haven’t seen much rain for a while. It’s been warm. Now we’ve got downslope winds. So they’re combining to create that critical fire weather.”
A fire weather watch for the Stanislaus National Forest and portions of Tuolumne and Calaveras counties was in place for 11 p.m. Monday through 8 a.m. Wednesday. Just before noon Monday, Kurth said he and his colleagues were going to upgrade the fire weather watch to a red flag warning for heightened fire dangers, with the same timing.
Portions of Amador and Alpine counties were also included in the fire weather watch area before noon Monday.
Dry winds out of the north and east could be a particular concern in Tuolumne and Calaveras counties from 7,000-foot elevations down to 3,000-foot levels, which include communities along the developed Highway 108 and Highway 4 corridors.
“We have a high pressure ridge that builds over eastern Oregon and into the Great Basin and that high pressure wants to go to the low pressure areas to the west,” Kurth said. “Especially those canyons aligned northeast to southwest.”
Daytime highs in the Sonora area from Monday to Wednesday were expected to be in the 80s, with overnight lows in the 50s, with little moisture recovery overnight during the fire weather watch and red flag warning alerts through Wednesday morning.
Potentially stronger winds are possible again Wednesday night and into Friday morning, but that could be north of the Stanislaus National Forest, and there’s another chance for breezy winds and fire weather concerns in or near the Central Sierra on Sunday.