UPDATE (9:06 a.m.): Caltrans says due to a break in snow, the CHP is currently not pacing traffic on the Grapevine. All lanes are open and in "freeflow".
Weather has led the California Highway Patrol to pace traffic on the Grapevine on Thursday morning.
According to the CHP's traffic website, snow has led to round robins on Interstate 5.
The Los Angeles CHP is reporting "heavy snow" in the area of Highway 138 on the Grapevine.