DISASTERSA Tropical Storm in California? Warmer Waters and El Niño Made It Possible.

By Naveena Sadasivam

Tropical Storm Hilary made landfall in Mexico and crossed into California last weekend, knocking out power and drenching wide swaths of southern California. Parts of the desert terrain in the region, which typically receives less than a quarter inch of rainfall a year, received between two and four inches of rain. According to the National Weather Service, downtown Los Angeles received 2.48 inches of rain on Sunday, breaking a single-day record from 1906 of 0.03 inches.  

The downpour felled trees, caused mudslides, and closed roads. East of Los Angeles, in San Bernardino, police ordered evacuations in several communities. More than 35,000 Californians are out of power as of Monday, and several school districts canceled classes to assess the damage of the storm. Major sporting events including a Major League Soccer match and several Major League Baseball games over the weekend were also rescheduled.

The storm made landfall as the rest of the country was grappling with other climate-fueled disasters. Devastating wildfires in Lahaina, a historic town in Maui, Hawai’i, killed more than 110 people and caused billions in damage. Across the country, dangerous heat conditions persisted, with the National Weather Service warning that a heat dome will “consume” the Plains and Mississippi Valley into the South this week. Two major fires burning in Spokane, Washington, have also torched a combined 20,000 acres, leading officials to order the evacuation of the nearby town of Medical Lake. On the East Coast, meteorologists are tracking two storms brewing in the Atlantic.

Hilary strengthened in a hurry last week. On Thursday, the National Weather Service reported that it was a Category 3 hurricane with wind speeds of 120 miles per hour, and by Friday, it had strengthened into a powerful Category 4 storm. The center warned that Hilary would bring “life-threatening and potentially catastrophic flooding” over the weekend. The forecasts triggered California’s first-ever tropical storm warning. But as the hurricane crossed cooler waters off the coast of southern California, it lost its strength and was downgraded to a tropical storm.

Still, Tropical Storm Hilary “really did produce all-time, record-breaking summer rainfall across most of the region,” said Daniel Swain, a climate scientist at the University of California, Los Angeles. “In terms of the incredible frenetic pace of global extremes we’re seeing this summer, that is only going to get worse as the climate continues to warm.”