Yasmeen Kerflani was last seen yesterday afternoon in the Halton area.
She is 5ft3ins with brown/red shoulder length hair. She was last seen wearing a dark blue/black hood coat with black trousers and grey/brown ankle boots.
Police think she might have travelled to London.
Police and her family are concerned for her welfare.
Anyone who has seen Yasmeen or can help police with their appeal is asked to call police on 101.