A cold, late-season storm moved into Southern California on Thursday, bringing thunderstorms, lightning, scattered showers and even hail to the drought-parched region.
Rain that began to fall midday Thursday was heavy at times, triggering flash flooding in Hollywood, West Hollywood and other areas. The storm was expected to taper off overnight.
In Northridge, firefighters rescued a young man from the Los Angeles River who was found clinging to a piece of concrete.
"Within a very short period of time, he was up in the waist-deep water and he's lucky he had something to grab onto -- because it only takes about 6 inches of moving water to knock you off your feet," said Battalion Chief Carlos Calvillo with the Los Angeles Fire Department.
The victim was transported to a hospital suffering from possible hypothermia.
The storm also brought snow to the local mountains and could threaten wildfire burn areas with mud and debris flows. Waterspouts were possible over the ocean.
Residents in the burn areas around the Colby, Springs and Powerhouse fires were advised to prepare for possible minor mudflows.
Snow levels were expected to fall to 5,000 to 6,000 feet, and forecasters warned of winter driving conditions on mountain roadways. KTLA's stationary camera at Snow Summit, one of the Big Bear resorts, showed snow was falling by early afternoon.
The Grapevine was not expected to see an accumulation on the roadway.
A cold-weather alert was issued by the Los Angeles County Department of Public Health for mountain areas, where wind chill temperatures could dip below 32 degrees.
A wind advisory was issued for the Antelope Valley through 10 p.m. Friday. Gusts could reach up to 55 mph in some areas, and blowing dust and sand could affect visibility.
A second wave of rain was expected to be heavier on Friday, according to the National Weather Service.
A flash-flood watch was set to be in effect beginning Friday morning for the Santa Ana Mountains and foothills, as well as ranges in Riverside and San Bernardino counties.