The way you worded that makes it sound as though there was a massive overhanging cornice of snow in those years. In fact, there is snow every year, some more than others, and the rebuild of the westbound lanes of I-90 made avalanche control and routine road maintenance easier and safer.
Check this west summit webcam in the morning.
http://www.kirotv.com/s/weather/snoqualmie-pass-cam/
What I’m talking about was just one year in particular, where an abnormal build-up and one big storm resulted in an avalanche that took out several miles of the road and lots of cars with it.