Update 3:29 p.m.: Thunderstorms, flood warnings hit mountainous areas in SoCal
Scattered thunderstorms unleashed fierce downpours and sporadic showers in areas around Southern California Thursday as the normally bone dry month of July comes to unusually humid end.
A surge of monsoon moisture and atmospheric instability set the stage for dramatic thunderheads that boiled up over rugged mountain ranges. Other areas of the county remained sunny with blue skies.
Flash-flood warnings were issued for northwestern Los Angeles County, northwestern Ventura County, north-central Santa Barbara County, and southern San Bernardino County, the National Weather Service said.
Doppler radar estimated as much as 2.5 inches of rain in parts of eastern Santa Barbara County and nearly 2 inches in northern Ventura County. Areas including Cuyama, western Lockwood Valley and Ventucopa were warned of possible flooding.
In the inland desert region east of Los Angeles, a flash-flood warning was issued as more than an inch of rain fell near Joshua Tree. Warned communities included Twentynine Palms and the nearby Marine Corps base, Yucca Valley and Landers.
Meteorologists warned drivers not to attempt to cross flooded roads.
Forecasters also said the possibility of thunderstorms could extend across the San Joaquin Valley and in the Sierra Nevada from about Yosemite southward.
Downpours also hit Wednesday in the high desert north and east of Los Angeles, sending flows of water across roads.
The weather service said a chance of storms would persist Friday and into the weekend but the atmosphere would begin drying out as the flow of air shifted from the southeast to a more southerly direction.
10:47 a.m. Flash flood watch continues across Southern California
A flash flood watch continued Thursday for the Antelope, Cuyama and San Gabriel valleys, according to the National Weather Service.
Showers and thunderstorms were expected in Los Angeles County early in the morning before moving up into Ventura and Santa Barbara counties.
The stormy weather could bring heavy rainfall, with rates of 1 to 2 inches per hour through the evening, the NWS said.
Flash flooding can lead to mud and debris flows, rockslides and blocked roads and can happen even in areas where there has been no rainfall. Particularly vulnerable are areas that have recently burned. The NWS noted the flash flood watch area includes the area burned by the Colby Fire in Glendora last year.
— KPCC staff