With the Thanksgiving Holiday coming this week, Caltrans is giving an early heads up to drivers planning to use the I-5 over the Grapevine. 
The warning covers the area before and after the Templin Highway exit, where a mudslide and continuing repairs will have some lanes closed.  Here are the full details, according to Caltrans:

Castaic between the City Santa Clarita (Valencia) and the “Grapevine” — The California Department of Transportation (Caltrans) advises motorists traveling over the upcoming Thanksgiving holiday on the Golden State Freeway (I-5) north of Santa Clarita at Templin Highway near the “Grapevine” to please PLAN AHEAD and LEAVE EARLY to avoid expected holiday-related delays due to an ongoing lane closure on northbound I-5 at Templin Highway for mudslide and slope stabilization repairs.

Three northbound lanes and four southbound lanes remain open to motorists.

Alternate routes are recommended wherever possible. In Santa Clarita, The Old Road is a suggested alternate route during periods of congestion.

For road conditions in California (excluding unforeseen traffic incidents) please call the Caltrans Highway Information Number at 1-800-427-ROAD (7623). By speaking the number of the route desired — or using a touch-tone telephone and simply entering the highway/route number of interest, callers can get up-do-date road conditions on any highway in California. Motorists are also encouraged to tune into local radio stations for up to-the-minute freeway reports before starting out on trips.

Caltrans thanks the motoring public for their patience during these roadway repairs. For more information, please call the Caltrans Public Affairs office at (213) 897-3656 or 897-3630 from 8 a.m. to 5 p.m. Monday through Friday.

Caltrans reminds motorists to please drive with extra caution while traveling through freeway work zones. Please, SLOW FOR THE CONE ZONE.