It's snowing against in the Mt. Shasta area, and Caltrans reported R1-Modified chain controls on Interstate 5 north of Redding as of 2:30 p.m. on Monday.

As of approximately 2:30 p.m. on Monday, Jan. 25, all big rigs travelling north bound on Interstate 5 are being screened for chains 10 miles north of Redding at the Fawndale exit #689
Currently R1-Modified conditions are in effect at South Dunsmuir, according to a report from Caltrans.
R-1M means chains are required on single-axle drive vehicles with trailers.
For updated chain controls go to: caltrans2.info or www.dot.ca.gov/dist2/chainup/allcntys.htm