The California Highway Patrol and Caltrans announced the shutdown about 9:44 a.m., adding that the northbound 5 was closed at Parker Road in Castaic and southbound lanes were closed at the base of the Grapevine.
Around 3:15 p.m., the Grapevine and northbound 5 in Castaic were reopened after plow vehicles cleared out the snow and ice.
***SIG ALERT*** I-5 IS CLOSED N/B AT PARKER RD AND S/B AT BASE OF THE GRAPEVINE FOR UNKNOWN DURATION. ALT RTE, SR-14 TO SR-58 OR SR-126 TO US-101. pic.twitter.com/cSLFpojaGa— CHP Newhall (@CHP_Newhall) December 6, 2018
Footage from AIR7 HD showed traffic backed up for miles as vehicles sat on the highway, getting covered in snow. Plows and other vehicles were on one side trying to clear the snow and ice off the roadway.
Stranded motorists said they were frustrated to be delayed before the Grapevine, but were grateful not to be in the slushy mess.
Meanwhile, a crash on the rain-slicked 5 prompted the shutdown of three northbound lanes near Hollywood Way in Sun Valley shortly before 10 a.m., according to Caltrans. The official cause of the crash was under investigation.
Earlier Thursday, a crash along the rain-slicked northbound 5 Freeway near Griffith Park caused a massive traffic backup.
The wreck occurred sometime before 6:30 a.m. near the Colorado Boulevard exit before the 134 Freeway interchange.
The incident initially prompted all northbound lanes to be shut down. Lanes were reopened, but gridlock conditions remained for miles.
The cause of the crash was not immediately available.