The collision occurred about 6 a.m. near milepost 98.
Washington State Patrol trooper Guy Gill said the woman’s car was stopped on southbound I-5 in the slow lane without lights on when the semi struck it. It’s unknown why her car was stopped on the highway but troopers found prescription drugs in her vehicle.
The semi driver was not injured. The woman was flown to Harborview Medical Center in Seattle.