The trooper was not injured in the Friday morning incident.
"The trooper was actually standing outside his patrol car contacting the car he had stopped, and it was more of a sideswipe, not a rear-end (crash)," said Trooper Mark Francis.
On Monday night two patrol cars stopped on I-5 in Seattle were damaged in a rear-end collision caused by a suspected drunk driver.
Then on Wednesday night, a trooper was stopped along I-405 in Kirkland with a disabled car. When a car slowed down past the scene, that car was struck by a hit-and-run driver who didn't stop, forcing the first car into the trooper's vehicle, leaving the officer with minor injuries.
Trooper Francis tells KOMO News that all troopers have close calls.
"They train our troopers in the academy - always keep their head on a swivel, not to walk backwards, I mean just constantly check your traffic because you just never know when that time is when somebody's gonna drift off or get sucked in to your light," Francis said
In 2012, a total of 44 state patrol vehicles were hit by motorists, usually while the trooper was parked on the shoulder.