Roads all across the valley will be freezing up and turning icy tonight.  At 5pm Salem was at 35° with a rain/snow mix.  Besides the usual cooling we get at night, colder air is continuing to move in from the north.  

Hard to say when roads will ice up.  My best guess is roads should be fine/just wet until 9pm, but could be icy sooner, so drive carefully and pay attention before leaving.  This of course will affect the morning commute.