Leah Swinfield was seen leaving her home shortly after 12.30am on Sunday 4 July and has not returned.
She has been missing for more than 24 hours and both her family and officers are concerned for her welfare.
Leah, who is 5ft 1ins tall, may have travelled to Leicester at some point. She is of a very slim build and has long, curly hair which is half ginger and half pink.
The clothing she may be currently wearing is unknown, but she generally wears leggings and a hoody.
Anyone who has seen Leah, or knows of her whereabouts, should contact police on 101, quoting incident 571 of 4 July.