Jordan Cooper was last seen nearly two weeks ago when she went to Bognor Regis with a family member, but was reported missing on Monday after she failed to return home on Sunday.
Jordan is described as white, 5ft tall and of slim build with straight brown shoulder-length hair. She usually dresses casually in jeans, leggings or jogging bottoms.
Missing persons co-ordinator Shannon Marchesani from Sussex Police said:
“We believe that she could still be with a family member and people known to her in either Bognor Regis, Newquay, Devon or on the Isle of Wight.
“Please can anyone with information about where she is to contact us as soon as possible.
“We are worried about Jordan because of her age and because this is out of character. She is also missing the start of the school year.”
Anyone with information about her whereabouts should email [email protected] or call 101 quoting Sussex Police serial 579 of 07/09.