Britany was last seen at around 9.30am on Sunday (5 December) in the Allerston area near Pickering.
And her black Kia Picanto car was found nearby.
Concerns for Britany’s safety were raised by her worried family at 4.30pm on Sunday.
Police searches, supported by mountain rescue team volunteers and a police helicopter, are ongoing in and around Dalby Forest.
Britany is described as white, with long straight blonde hair and a slim build.
Police believe she was wearing grey leggings, a white and black jumper, possibly a hi-viz riding top, and a pale pink body warmer with a hood.
If you recall seeing a woman matching Britany’s description please call North Yorkshire Police without delay on 101, select option 1, and speak to the Force Control Room.
Please dial 999 if you have an immediate sighting quoting reference number 12210255354.