FIRE IN THE SKY
NWS: Fire generated its own thunderstorm amid ‘extreme’ conditions
PULGA >> Unusual weather conditions caused Northern California’s Dixie Fire to generate its own overhead thunderstorm Monday, with wild winds and “extreme, extreme” conditions accelerating its rate of spread, officials said.
The “pyro cumulonimbus” cloud system formed as the effects of a southwestern monsoonal surge reached the fire area in Butte County. Fast-rising hot air from the fire’s tallest columns combined with monsoonal moisture to create ripe conditions for stormy skies.
“It’s very crazy,” said Cory Mueller, a National Weather Service meteorologist with the Sacramento region. “You don’t want to see lightning strikes coming off of a fire — it’s obviously dangerous for anyone fighting the fire, but when you see it, it means you’re likely having very intense fire growth.”
The Dixie Fire broke out last week about 10 miles from the community of Paradise. It remained relatively stable
for several days — burning northeast and away from the footprint of the 2018 Camp Fire — before exploding over the weekend.
As of Tuesday morning, the blaze had grown to more than 60,000 acres, up from about 40,000 acres Monday night, and was about 15% contained. Two structures have been destroyed, with more than 800 more threatened.
Evacuation order and warning zones have been expanded to include Jonesville, Philbrook, High Lakes, Seneca, Bucks Lake, Snake Lake, Meadow Valley, Tollgate and the Highway 70 communities of Rock Creek, Storrie, Tobin, Belden and Twain. Highway 70 is closed between Jarbo Gap and Highway 89.
In a briefing, Cal Fire’s incident meteorologist Julia Ruthford said that the fire’s columns peaked at about 30,000 feet at the start of the week and climbed even higher Monday afternoon as the midlevel moisture gathered overhead.
“That led to some lightning out ahead of it and some really gusty, erratic winds due to that extreme, extreme conditions due to the thunderstorm,” Ruthford said. “Overall, we’ve been in an extremely critical fire weather pattern.”
It’s “fairly unusual” for fires to create their own weather, said NWS’ Mueller.
But Dixie isn’t the only blaze to do so this week: The massive 388,000-acre Bootleg Fire along the Oregon border also generated pyrocumulonimbus activity over the past few days, allowing for dramatic spread and high winds.
The unpredictable phenomenon arrived during a challenging wildfire season up and down the West Coast. In Plumas County, the Beckwourth Complex had burned about 105,00 acres as of Tuesday morning and was about 88% contained, according to the U.S. Forest Service. To the south, Alpine County’s Tamarack Fire had engulfed nearly 40,000 acres.
Through the end of the week, the chance of thunderstorms in Dixie’s path will lessen as the moisture sloughs off and conditions return to more typical summer patterns, with temperatures in the 70s and 80s and 10-20 mph winds, Mueller said.
Crews on Tuesday planned to protect against unpredictable growth in the Belden and Rich Bar areas and strengthen contingency lines from Chips Creek to High Lakes. But they also braced for a sudden drop in humidity that will mean trading one weather concern for another, Ruthford said.
“I wish I had better news on that front, but we’re looking at more dry, breezy weather coming up,” she said.