Police say the woman was jogging northbound on Mt. Grey Road when she passed a man who was walking northbound at 6:35 a.m.
As she passed the man, authorities say he asked her a question. She responded and kept jogging.
According to police, the man then ran behind her and grabbed her with one arm while groping her inappropriately with the other.
Investigators said the victim heard a vehicle approaching and believes the subject also heard the vehicle, which gave her a chance to break away and run.
The woman driving the vehicle picked up the victim, while the man fled southbound on Mt. Grey Road.
The man is described as white, 17 to 21 years old, 5 feet 6 inches tall, with a thin to medium build. He has blonde crew-cut hair and blue eyes. He was wearing a white t-shirt, dark shorts and dirty grey skater type sneakers.
Detectives are asking anyone with information about this incident to call the Sixth Squad at 631-854-8652 or anonymously to Crime Stoppers at 1-800-220-TIPS. All calls will remain confidential.