Prosecutors say Andrew Patterson was firing at someone else across a street and hit Justin Ferrari as he drove through an intersection with his parents and two young children in the vehicle.
Ferrari had just picked up his parents from the airport and was leaving town for a Memorial Day weekend vacation.
Prosecutors say the standard sentencing range is roughly 15 to 23 years and they will recommend the judge give Patterson 19 1/4 years.
"The random, tragic and senseless death of Justin Ferrari was the result of this defendant's decision to use a gun to settle a petty dispute," King County Prosecutor Dan Satterberg said in a statement released to the media. "Every person in the neighborhood was a potential victim of his irrational and erratic use of deadly force."
Sentencing is scheduled for Aug. 23.