All roads leading to Idyllwild have closed as the "atmospheric river" storm enveloping Southern California continued to rage Thursday afternoon.

Highway 74 is closed from Willowbrook Road, east of Valle Vista, to Highway 371 at the southern border of the San Bernardino National Forest. Portions of Highway 243 were also closed, from Hurley Flats Road, north of Lake Fulmor, to Highway 10. Highway 243 connects Banning to Idyllwild and Highway 74 connects Hemet and Anza to Mountain Center, another San Jacinto Mountain town five miles south of Idyllwild.

Last summer's Cranston Fire damaged the San Bernardino National Forest surrounding Idyllwild and, due to increased potential for landslide in "burn scar" areas where trees and brush can no longer prevent tumbling mud, rocks and debris, Riverside County officials issued a voluntary evacuation order late Tuesday for areas affected by last summer's fires.

A lane on Highway 243 near Lake Fulmor collapsed due to a sinkhole opening, according to the California Highway Patrol. Sinkholes can open when water drainage patterns change or when new pressure -- including weight from rock or mudslides -- damages the earth above underground cavities.

Care and reception centers are open at Banning High School in Banning and Hamilton High School in Anza for residents evacuated or unable to return to their homes in Idyllwild.