Slow-moving thunderstorms moved across Southern California mountain ranges Friday afternoon, triggering heavy downpours, flash flooding and hail.
Most of the rain fell in the San Gabriel and San Bernardino mountains and in the Antelope Valley, as well as in northern Ventura County, the National Weather Service’s Oxnard station said. Up to a half-inch of rain was possible.
By about 2:30 p.m., thunderstorms were developing along the 5 Freeway corridor near Pyramid Lake, in Castaic, the weather service said on Twitter.
A flash-flood warning was issued for northeastern Los Angeles County about 4:30 p.m., and it was set to continue through 7:15 p.m.
Areas that were expected to experience flooding included the eastern San Gabriels, the Powerhouse Fire burn area near Lake Hughes, Lancaster, Lake Los Angeles and Llano.
Emergency crews with the Los Angeles County Fire Department responded to a rollover crash just before 4 p.m. near Avenue K and 70th Street East in Lancaster.
An 18-year-old driver lost control of her vehicle on a slick road and flipped over.
She and her 14-year-old sister, who was also in the vehicle, were not seriously hurt.
Flooding was also reported along Highway 138 in eastern Palmdale as well as in Llano where a mudslide covered much of Largo Vista Road.
A flash-flood watch was in effect from 2 to 9 p.m. in mountain ranges in Los Angeles and Ventura counties, and in the Antelope Valley. The Santa Monica Mountains were not subject to the flash-flood watch.
The storms come during a week in which rainfall records were broken in multiple locations in Southern California, which was saw unseasonable precipitation due in part to Tropical Storm Blanca. Monday, on the other hand, saw record high temperatures in some areas of the region.
Friday’s storms were the result of a “relatively moist and unstable air mass” coming into the region, the weather service said.
The predicted slow speed of the storms was likely produce heavy rainfall in areas, sending torrents down steep terrain and potentially flooding roadways with swift-moving water, according to the weather service.
Scattered showers and thunderstorms were expected in the high desert and mountains of San Bernardino County, bringing the possibility of small hail, gusty winds and heavy rainfall.
A flood advisory was issued through 7:15 p.m. for San Bernardino County, with heavy rain expected near Phelan and Pinon Hills.