Wildfire creates own lightning as it more than doubles in size
A wildfire in Northern California more than doubled in size from Friday to Saturday, sending up a massive cloud of smoke and ash that combined with the dry heat generated its own lightning and created dangerous weather conditions for firefighters, authorities said.
The Sugar fire, which ignited July 2, had spread to 54,421 acres and was 8% contained as of Saturday morning. The fire, now the state’s largest of the season so far, was one of two sparked by lightning in the Plumas National Forest that have together been dubbed the Beckwourth Complex Fire. The other, the Dotta fire, started June 30 and was 670 acres and 80% contained by early Saturday.
Fueled by a midweek heat wave that exacerbated already hot, dry conditions, the Sugar fire made a huge run Friday, triggering new evacuations for portions of Plumas and Lassen counties, as well as part of Washoe County, Nevada. The Washoe County evacuations were lifted Saturday but residents were advised to stay vigilant. About 2,800 people remained under evacuation orders or warnings, officials said.
Firefighters were bracing for another day of extreme conditions amid even hotter temperatures.
“As long as it’s this hot and we have these low humidities, it’s kind of hard to tell when and where we’re going to catch this,” said Lisa Cox, information officer for the Beckwourth Complex fire.
Fire crews were seeing group torching and longrange spotting as flames tore through timber stands, she said.
“That increases the velocity of the spread of the fire because the fire’s actually moving amongst the treetops,” she said. “Basically, it just runs across the trees until it runs out of trees.”
Such intensity, combined with hot, dry, unstable conditions, can generate a thunderstorm cloud as the fire did Friday afternoon, when the incident meteorologist observed cloud-to-cloud lightning, Cox said.
So-called pyrocumulonimbus clouds can, in turn, make the fire spread even faster — in addition to lightning, they can create erratic, ember-spitting winds.
“Yesterday, our operations staff was reporting spotting about a mile ahead of the main head of the fire,” Cox said.
Pyrocumulonimbus clouds — as well as pyrocumulus clouds, which are similar but do not produce thunderstorms — tend to rise up in the afternoon when it is hottest and can pose an additional danger when they fall as things cool off.
The Thomas fire creates a huge pyrocumulus cloud in December 2017.