In the north-western states (Washington, Oregon), the weather is cool and rainy along the west coast and along the west-facing slopes, in cities like Seattle, Portland, and Eugene. Average temperatures in winter
In order for disturbances to become winter storms there are three key factors: cold air (below-freezing temperatures facilitate the production of snow and ice); moisture (which forms clouds and precipitation); and lift (which raises the moist air to form clouds, precipitation, and fronts). ...