That air in the valley floor continues to cool due to radiational cooling, the air becomes so saturated, the humidity level reaches 100%, when fog forms. Radiation fog varies in depth from 3 feet ...

(KATU) — Patchy freezing fog and slick streets greeted Monday morning ... “This would be widespread this time around for the valley floor.” The National Weather Service in Portland says ...

High pressure will remain overhead through the weekend, keeping stable conditions, mostly clear skies and above average afternoon temperatures (upper 40s and 50 ...