Aimee, 16, was last seen in the Redhill Avenue area in the early hours of Thursday, June 4, after leaving an address.
She was reported missing shortly afterwards.
The 16-year-old is described as being 5ft 8ins tall, of medium build, with long black hair tied in a ponytail and was last seen wearing a black jumper, black trousers, and grey trainers.
Read more: 15-year-old boy reported missing on Sunday still not found
Chief inspector Rachel Vallins of Dorset Police said: “We are concerned for Aimee’s welfare and are carrying out searches to locate her and make sure she is OK.
“I would urge anyone who has information regarding her whereabouts to please contact us immediately.
“I would also like to make a direct appeal to Aimee – if you see this, please make contact with us or your family and let us know where you are.
“We all just want to check that you are all right.”
Aimee is known to have links to Southampton and Portsmouth and is believed she may have travelled by train towards London.
Anyone with information is asked to contact Dorset Police quoting incident number 4:41.