We live near Olympia and had to go to a funeral in San Antonio in early Feb last year and we just took I90 to the Yakima turn off and then took I82 to Pendleton and caught I84. The snow was deep along side the road but they really keep the interstates as free of ice as they can for the truckers and we didn't even see any wet spots. Then if I were going to Phoenix I'd take 93 south. The secret is to just watch the weather and leave when you see a dry spot in the future. Stay at a hotel instead of in the RV when you get to Baker or La Grange so you can keep the rig winterized. Id probably stay in a hotel at Twin Falls or Ely also but both places have some nice RV parks so just make the decision when you get there. I suggest stopping as tired driving in winter just isn't smart. Happy travels.
