A collision of extreme weather events is bearing down on California as wildfires threaten communities, a record-setting heatwave is adding stress to the electrical grid, and moisture from a hurricane is expected to bring thunderstorms and flash floods.
Hurricane Kay, swirling off the coast of Mexico, is on its way north, bringing with it the chance of strong winds, severe rainstorms, and possibly dry lightning that could increase risks for new fire starts. It also could bring some welcome relief to the week of brutally hot weather.
“This is perhaps the singularly most unusual and extreme weather week in quite some time in California – and that is saying something,” wrote Daniel Swain, a climate scientist at the Institute of the Environment and Sustainability at the University of California, Los Angeles, in an analysis on Wednesday.
Although it remains uncertain how, exactly, Kay will develop, models show the storm will slow before hitting southern California, Swain said. “But it is quite possible that portions of southern California will see heavy rainfall and strong winds” he said, adding that even an indirect impact from Kay could result in tropical storm force gusts. Those winds increase the risk of new wildfire initiations, especially in San Diego county, he said.
The outer bands of the big storm could also bring heavy rain and possibly flash floods to parts of scorched southern California and south-western Arizona on Friday night and Saturday, the US National Hurricane Center warned. Farther north, where rain is less likely, the chance of dry lighting influenced by the hurricane is also causing concern.
Despite the initial impacts of Kay, forecasters warned that the heat was not yet done.
“The seemingly endless heatwave that has been plaguing California will finally be coming to an end across at least southern California, but not before two more very hot days and very warm nights,” the Los Angeles-area weather office wrote.
Operators of California’s power grid issued another alert, calling for residents to restrict their electricity use as demand, which can spike during a heatwave, strains the state’s energy resources.
Meanwhile, firefighters are struggling to gain control of wildfires that have forced extensive evacuations. These include the Mosquito and Fairview fires, which grew explosively in recent days, exhibiting dangerous behavior, producing erratic fire swirls, ominous smoke formations, and flames that surged hundreds of feet high.
The Fairview fire in southern California expanded in two directions, and covered more than 19,000 acres by Thursday , with just 5% containment. The blaze burning in Riverside county, which claimed the lives of two people and severely burned several others as they tried to flee, has chewed through parched vegetation and complex terrain, officials said. Seven structures have been confirmed destroyed but several communities remain under threat.
To the north, the Mosquito fire grew rapidly in the Sierra Nevada, forcing evacuations in Placer and El Dorado counties. The blaze exploded in size overnight, spreading across 6,807 acres by Thursday and was 0% contained. Several structures and at least 10 cars near the Gold Rush-era community of Michigan Bluff, about an hour north-west of Sacramento, have been destroyed. The Nevada Division of Environmental Protection warned the Reno area that air quality could be very unhealthy to hazardous due to smoke from the Mosquito fire.
The fire’s cause remained under investigation.
“As you’ve seen with the smoke column coming up, this fire continues to give us a hard time,” said Cal Fire division chief Mike Rufenacht in a video briefing.
Another dangerous blaze burned in stands of timber near the Big Bear Lake resort region in the San Bernardino Mountains east of Los Angeles. It was just 2% contained after scorching nearly 1,200 acres .
The rapid escalation in fire activity across the country prompted officials to bump the national preparedness level to 4 (on a scale of 1-5), as more resources were being requested and deployed to battle the blazes. Eight new large fires were reported on Wednesday alone, as 71 continue to burn across the west. The number signifies that more than half of the country’s resources for fighting fire are committed.
As fall sets in, the risk of fire conditions, especially in northern California and parts of the Pacific north-west, is expected to rise. Landscapes across the drought-stricken region are primed to burn after being baked for months in the summer heat, with little chance of an early rainy reprieve.
Fire is a natural part of the climate in the west and cycles of drought are normal. But the climate crisis has upped the stakes, and warming has set the stage for increasing intensity while also pushing higher threats deeper into shoulder seasons when they are more likely to align with other disasters. Compounding catastrophes that build on one another, testing capacity of response systems and straining resources, are on the rise.
“Additional fires are possible over the next few days as extremely hot conditions continue and anomalous patterns/isolated lightning strikes occur ahead of a tropical weather system,” Swain said, adding that the heatwave had served to squeeze even more moisture out of the bone-dry vegetation, “setting the stage for extreme burning conditions given favorable weather conditions” in several areas across the state even without the added influence from Kay. “A converging record-breaking heatwave and northward-moving hurricane make for an extremely challenging forecast.”