Actually the current warm (except at night) and clear period in the PNW has more to do with weather than climate. There's a large persistent ridge of high pressure off shore that's deflecting the moist ocean air around us. And seasonally the amount of snow has more to do with LaNina/Nino oscillations that with long term climate trends.
http://cliffmass.blogspot.com/2018/10/ridgezilla-returns.htmlWe just camped in Winthrop on the NE side of the Washington Cascades (about 2000 ft). While day temperatures were warm (60s?), early morning temps were freezing.
97 and 31 are on the dry side of the Cascades. Willamette Pass on 58 is just a bit higher than 97. The 7d forecast for Crescent on 97 is for highs around 70, and lows below freezing - and clear. Lakeview which bills itself as the highest town in Oregon is actually a bit warmer.
The longer term forecasts expect this ridge to weaken, and a regional return to wetter weather. But that will have more effect on Eugene than over the mountains.
Just keep an eye on the forecasts and Oregon Tripcheck for highway conditions. As long as they don't predict a major storm off the ocean I don't expect bad driving conditions. And if a store comes, it's as likely to produce snow on the I5 pass as on 97 and 395. I5 is lower, but closer to the ocean.
The other thing that could adversely affect driving in the interior is a mass of cold air from Canada, and I don't see that in the forecast.
