Tia, 16, was last seen yesterday afternoon, and officers have been conducting extensive searches to find her.
We believe she is still in the Farnborough or West Drayton areas of London.
She is described as white, about 5ft 5ins tall, with auburn hair that is usually pulled back in a bun.
If you have seen Tia or have any information about her whereabouts, please call 101 and reference 44220289555.
