The father of Charlotte Anna Molinari contacted police around 9 p.m. Saturday, Sgt. Lisa Banayat said. He said his daughter had left on her bike around 9:45 a.m. that day, possibly bound for Spring Lake.
Santa Rosa police are searching for the girl and have requested mutual aid from the Sonoma County Sheriff's Office helicopter and search-and-rescue teams, Banayat said.
There is some evidence Charlotte might be depressed, Banayat said. She normally attends Sonoma Academy but has not been seen by her fellow students, according to Banayat.
Charlotte is white, 5 feet 9 inches tall, weighs 150 pounds and has curly brown hair and brown eyes, police said.
She was wearing a dark blue knee-length coat and was carrying a green backpack. She was on a green mountain bike and had a laptop and ukulele with her, Banayat said.
Police are asking anyone with information about her to call Detective Jeneane Kucker at (707) 543-3595 or the dispatch center after hours at (707) 528-5222.