Showers and thunderstorms produced heavy rain and hail in the area north of Castaic from the Golden State (5) Freeway to Lancaster and points east.
About 2 1/2 inches of rain fell in the affected area, portions of which were covered with golf ball-sized hail.
Rainfall records for Oct. 15 were set in Palmdale (0.94 of an inch) and Sandberg (0.65 of an inch), breaking the previous records of 0.04 of an inch and 0.15 of an inch, both set in 1935, according to the National Weather Service.
A record was also set at Fox Field in Lancaster, where 0.65 of an inch fell, breaking the previous record of a trace amount set in 2005.
The National Weather Service had earlier issued flash-flood warnings and said downpours could cause slides and flows of mud and debris over slopes that wildfires have stripped of vegetation, including the Powerhouse and Warm fire burn areas.
Flooding was reported by the National Weather Service near San Francisquito Canyon and Elizabeth Lake roads and a funnel cloud was spotted near Lake Hughes.
Several homes were engulfed in mud in the Elizabeth Lake area and vehicles were trapped in mud flows on Elizabeth Lake Road in the Lake Hughes area.
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Aerial video showed a mobile home on its side, apparently swept off a road by a mud flow. Flood and mud also damaged homes in Palmdale.
Los Angeles County Fire Department rescue crews airlifted four people to safety after they became trapped in a vehicle, the department’s Humberto Agurcia said.
There were no immediate reports of injuries, but crews were continuing to survey the area on the ground and from the air in search of any other possible flooding victims.
The Golden State Freeway was blocked by rock and debris between Fort Tejon north of Gorman and Parker Road in the Castaic area and was expected to remain so until Friday evening, according to the California Highway Patrol. Dozens of vehicles were trapped on the northbound side of the freeway.
Northbound traffic was being directed off the freeway three miles north of Santa Clarita at Parker Road and southbound traffic at Grapevine Road, according to the CHP.
Dozens of vehicles were trapped on the northbound side of the freeway.
Patrick Chandler of Caltrans said Interstate 5 was choked by debris, mud and car-sized boulders and urged travelers to take a different route.
Finding alternatives was made difficult by flooding on other roads, however.
The CHP reported tonight that state Routes 14 and 58 were closed in the Mojave area in Kern County due to flooding, so southbound motorists were being advised to take state Routes 41 or 166 to southbound U.S. Highway 101 to eastbound state Route 126.
Northbound motorists were advised to exit the Golden State Freeway and take westbound state Route 126 to the 101 north.
A southerly air flow streamed into the area ahead of the storm system, bringing increased moisture and atmospheric instability, NWS forecasters said.
— Wire reports