Aaron Richard Brown III, 37, of Snohomish County was last seen at the Olympic Corrections Center's dining hall at around 4:35 p.m. Thursday, said Steve Gehrke of the state Department of Corrections.
Prison staff are investigating the circumstances of his escape.
Brown is described as a white male with hazel eyes, balding with blond hair, standing 5-feet-8-inches tall and weighing about 175 pounds with a medium build.
He was last seen wearing state-issued khaki pants and a red T-shirt. He has multiple scars and tattoos on his right upper arm and shoulder, his left shoulder, his back and his chest.
Brown had arrived at Olympic Corrections Center on Wednesday from the state prison in Shelton. He had been incarcerated at Shelton since June 27, when he began a 27-month sentence for drug possession.
A search was begun for Brown as corrections officers tried to determine how he escaped. The state Department of Corrections is the lead agency on the search, with assistance from Jefferson County Sheriff's Office, Washington State Patrol and the Hoh Tribal Police.
If anyone sees Brown or has any knowledge of his whereabouts, they are asked to immediately call 911. Although Brown's crime is not violent, he had previously served a prison sentence in 2010 for robbery, Gehrke said.
Olympic Corrections Center is located about 27 miles from Forks. It opened in 1968 and can house up to 381 prisoners.