Mike, not sure what routing you are taking but from now through the weekend, the mountains are getting the June July ski season snow. I would not plan on going east on 90 out of Seattle. Maybe south to Portland and then up the Columbia River Gorge if you are heading east this far north. That might be the most direct way and that's the way I would probably go. May be better conditions going south first, as far as California, but they have tons of snow in Sierra's too.
Enjoy the warm if you find it.
Harvey
SleepyC :moon