Thunderstorms threaten to worsen California fires including Caldor, or spark new ones
Critical fire weather conditions are expected Thursday evening and Friday due to a thunderstorm system set to pass through Northern California.
The National Weather Service has upgraded a fire weather watch to a red flag warning, in place 5 p.m. Thursday to 11 p.m. Friday for almost the entire northern half of the state and parts of the Central Valley.
Dry lightning refers to thunderstorms with minimal rainfall, which can present very high wildfire danger, especially given critically dry conditions during California’s current, severe drought.
“A combination of lightning, strong winds, low relative humidity, and warm temperatures can contribute to extreme fire behavior,” the weather service’s Thursday bulletin reads, in part.
The isolated thunderstorms could spark new wildfires or worsen existing blazes. The red flag warning covers zones where major wildfires are already burning, including the Dixie Fire and Caldor Fire.
“The highest chance of thunderstorms will be early (Friday) morning, as the cold front comes through” the Lake Tahoe Basin, said Zach Tolby, incident meteorologist on the Caldor Fire, in a video update posted Thursday by U.S. Forest Service officials. “We might see a little bit of rain with that, but in general, we’re expecting fairly dry conditions.”
Tolby said lightning strikes could not only threaten growth of the Caldor Fire, but could also pose a risk to fire personnel working on the incident. He said wind gusts could reach 60 mph along ridge lines and about 35 mph at lower elevations.
Before the thunderstorms, weather conditions had been mostly mild this week at the Caldor Fire, allowing for good containment progress.
Cal Fire and Forest Service officials reported the blaze, which has been burning in El Dorado County since Aug. 14, at 217,946 acres (341 square miles) with 53% containment.
Several evacuation orders have been lifted or reduced to warnings since last week, including for the city of South Lake Tahoe and much of the Pollock Pines area.
Other major fires still burning
The Dixie Fire, burning in parts of Butte, Plumas, Lassen and Tehama counties, was reported Thursday at 927,320 acres (1,449 square miles) with 59% containment.
Cal Fire in an incident report said “critical” weather warnings are in place on both the west zone and east zone of the Dixie Fire.
The Monument Fire burning in Trinity County has flared significantly this week, shooting past 200,000 acres Thursday.
The fire is 45% contained, but Shasta-Trinity National Forest officials wrote in a morning update that crews were battling “extreme fire behavior,” and the Trinity County Sheriff’s Office ordered new evacuations including parts of the town of Hayfork.
Red-flag conditions Thursday and Friday “have the potential to significantly increase fire growth around the perimeter of the Monument Fire,” Shasta-Trinity National Forest officials wrote Thursday morning.
“Residents in the vicinity of the fire area should be prepared to respond to changing conditions.”
This story was originally published September 9, 2021 at 2:16 PM with the headline "Thunderstorms threaten to worsen California fires including Caldor, or spark new ones."
