Washington State is divided naturally by two large land masses, the first are the Olympic Mountains which form the Olympic National Park and surrounding coastal areas of Salt Water on three sides, with the East side being a heavily populated area called the Puget Sound. This is where Bellingham, Seattle, Tacoma, Olympia and Lacey are located.
The second largest land mass is the extended mountain range of volcanoes running North to south from Canada to Oregon and parts of Northern California called the Cascade Range. These ares are crossable by passes, when the passes are open and not closed due to heavy snow or avalanche danger. The passes are 1. the North Cascades Pass, 2. Stevens Pass, 3. Snowqualmie Pass, 4. Chinook Pass, 5.White Pass. When these five passes are closed, the State is cut in half, with High desert and mountains to the east, and rainforest and deep a snows to divide the west.
The Eastern part of the state has basically several major areas, Spokane, the Tri-City Area of Pasco, Kinnewick and Richland and the Yakima and Wenatchee areas. The main highway routes are very good driving routes in excellent condition for the most part. To verify road conditions or pass conditions, get the following number for information: Contact the WSDOT website at - http://www.wsdot.wa.gov/traffic/passes/.