A storm system moved into Southern California on Monday, bringing with it the chance of thunderstorms and flash floods across large swaths of the region.
In the Los Angeles area, the threat of monsoonal showers — including brief heavy downpours and gusty winds — will linger through the evening, the National Weather Service said. Residents can expect a very muggy day, with humidity levels hovering near 90%.
Lighter showers are also moving through Orange County.
Experts said a low-pressure system embedded inside the typical summer monsoon pattern was behind the spate of moisture.
“It is related to monsoon season, which runs July through September, but this is particularly strong,” said Matt Moreland, a meteorologist with the National Weather Service in San Diego. “Normally you don’t see the rain in the cities in the lower elevations in the summertime.”
Increasing monsoonal moisture will bring a chance of showers and slight chance of tstms to the area through Mon evening. Brief heavy downpours and gusty winds are possible. Make sure to leave extra time for your commute and if thunder roars, head indoors! #CAwx #SoCal #LArain pic.twitter.com/qVDkhCTYW4
— NWS Los Angeles (@NWSLosAngeles) July 25, 2021
In L.A. County, Mt. Baldy was already the “rainfall winner,” with 0.37 inches by 5 a.m., said David Sweet, a meteorologist with the National Weather Service in Oxnard.
Downtown L.A. received .09 inches — enough to make it the area’s third-wettest July on record, he added. The wettest July ever in the city was in 2015, when 0.38 inches of rain fell. The second wettest was in 1886, with 0.24 inches.
“This widespread rainfall event would be considered unusual,” Sweet said. “This is unusual.”
The rain is expected to diminish Monday evening, but a few lingering showers will be possible Tuesday over the Los Angeles and Ventura County mountains, as well as portions of the Antelope Valley, Santa Barbara and San Luis Obispo County.
“Any area that receives more than a quarter of an inch will receive maybe 12 to 24 hours of enhanced moisture before things dry out again,” Sweet said, noting that some hillside vegetation is so dormant that it won’t even receive the rainfall.
“Let me just say,” he said, “this will do almost nothing for the drought.”
Still, Southern Californians who awakened to wet grounds and gray skies rejoiced in the moisture.
“It’s not much but it’s soooo welcomed. We need every drop we can get out here,” one person said on Twitter.
“More rain please!” said another.