8:49 A.M. UPDATE: Crews have cleared northbound Interstate 5 at J street after a jackknifed big rig blocked two lanes Thursday.
Offiicials say traffic is still slow in the area.
Two of the lanes are blocked. Authorities are urging commuters to take alternative routes.
#TrafficAlert:snarled traffic downtown I-5 NB at "J" blocking lanes 2&3 due to jack knifed big rig. Take alternate route. No ETO .— Caltrans District 3 (@CaltransDist3) January 12, 2017
Meanwhile, in the mountains, there are chain controls in effect for both Interstate 80 and U.S. Highway 50.
In Western Nevada, officials are urging drivers to be cautious. Snowy conditions continue to make roadways slick and dangerous.