Gardaí and her family are said to be seriously concerned for her welfare and say her disappearance is 'totally out of character'.
Sophie is described as 5 foot tall, weighing 7 and a half stone, with a slim build and dark hair.
When last seen, she was wearing a green jacket with a zip up the front, the jacket is a three quarter length, winter type jacket with a hood.
The teenager was last seen around 2.30am yesterday (Wednesday) morning leaving her home in Elm Park in Clonmel.
Gardaí in Clonmel are appealing to anyone who may have seen Sophie or knows where she is to contact them on 052-6177640 or the Garda Confidential Line on 1800 666 111.