More lightning, less fire damage than 2020 storm
Moisture, raised humidity mitigated effects
A thunderstorm event last week with 67,000 lightning bolts captivated Californians, who anxiously tracked the monsoon and hoped it wouldn’t ignite any catastrophic fires.
Data from the National Lightning Detection Network shows the storm largely outdid the number of lightning strikes that touched down in August 2020 and devastated parts of Northern California.
Tuesday’s storm traveled from the Mexico border to the northern San Joaquin Valley and west to the Big Sur coast. It carried with it lightning that ignited the Thunder Fire — which has since burned more than 2,300 acres in Kern County — and dozens of other smaller fires throughout the state.
Still, California was spared from a repeat of August 2020.
Then, a monsoon event touched down — after days of exceptionally hot and dry conditions — and brought at least 15,000 lightning bolts with it. Historic blazes exploded across the state, including the SCU, LNU and CZU Lightning Complex fires, which in total burned at least 2 million acres in just three weeks.
Last week’s weather conditions could have coalesced to create far more destructive firestorms.
But that didn’t happen, in part because the storm delivered moisture and raised humidity levels, UCLA climate scientist Daniel Swain explained.
“The storms this time around brought more precipitation; not very much, but more than zero, and it turns out that’s very important in terms of fire impacts,” Swain said.
And though the event produced some dry lightning, it was mostly a wet storm, unlike the one in 2020.
“If you only have dry lightning and you have soil that is as dry as California is right now, it is more likely to spark a fire,” said Jose Martinez-Claros, a postdoctoral scholar at UC San Diego’s Scripps Institution of Oceanography. “The moisture is what explains it.”
While the state faces mounting impacts from a historic multi-year drought, and vegetation in some places has dried out to levels normally seen in mid-summer, it’s still relatively early in the fire season.
Fuels are dry enough to carry wildfire — as last week has shown — but Swain said in many parts of the state green plants are interspersed with dry, dead vegetation. Some plants and trees are still holding onto water, just coming off the cusp of transition from spring to summer. That mixture makes a difference, he said.
“We’ve gotten so used to everything turning out to be the worst case scenario when it comes to wildfire … but the reason for that is how insanely dry the vegetation has been in recent years,” Swain said. “We just happen to be in a brief period where it’s not too bad.”
Leading up to the 2020 CZU Complex fires, large swaths of Northern and Central California experienced days of record-breaking heat.
While just last week Northern California and the wider Bay Area saw temperatures that rose to the triple digits and toppled records, the recent heat wave still wasn’t as severe as what took place two years ago.
Thunderstorms are rare in California, particularly on the coast, said Swain, who added that even more unusual are storms that produce tens of thousands of strikes, like the event last week. The fact that this thunderstorm arrived in June, as opposed to August or autumn, was also fortunate. Peak fire season is yet to come.
“If there is a lightning event in July, August or September this year, that may well be a completely different story,” Swain said. “In this moment, I think we got kind of lucky.”