A surprising amount of dry lightning hits California, fueling fire risk | CAS in the Media

Lightning strikes are rare in Northern and Central California — so infrequent as to be overlooked by science.

But the subject has been of urgent interest since August 2020, when a massive complex of thunderstorms thrashed its way across the state, dropping not rain but thousands of bolts of “dry lightning”: cloud-to-ground strikes without accompanying rainfall exceeding one-tenth of an inch (2.5 millimeters). The effects were predictable, immediate and immense: wildfires, 650 in total, burning upward of 2 million acres.

The first in-depth look at the region’s dry lightning events was published this month, prompted by that historic event. For a sunbaked land now deep into a drought, the top-line findings are ominous: There may be more of these strikes than realized.

“Our team knew dry lightning happens in California during the summer,” said the paper’s author, Dmitri Kalashnikov of Washington State University at Vancouver. “But we didn’t know that it would be almost half (46 percent) of all lightning strikes in 34 years that were dry.”

Previous studies have shown that while Southern California sees more human-caused wildfires, lightning-caused fires are more prevalent in the northern section of the state, particularly over mountainous terrain.

There’s currently one active lightning-sparked wildfire in California: the Six Rivers Lightning Complex, about 30 miles east-northeast of Eureka. It had burned more than 27,000 acres as of Tuesday morning and is about 80 percent contained. It began the evening of Aug. 5, when thunderstorms touched off 11 blazes.

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