Definitely not Mt. St. Helens. She's closer to Vancouver/PDX, not SEA. Winds at PDX are 120/12, which would push any ash from the volcano southeast.. Something else is going on up at SEA, as in the past 3 hours, they've only been in VMC once. otherwise, it's IFR in and out of that area.
Any other volcanoes up near there?
BL.