For Washington this means prevailing winds from the northwest bring relatively cool air and a predictably dry season.In the autumn and winter, a low-pressure cyclone system takes over in the north Pacific Ocean, with air spiraling inward in a counter-clockwise fashion.
It borders Idaho to the east, bounded mostly by the meridian running north from the confluence of the Snake River and Clearwater River (about 116°57' west), except for the southernmost section where the border follows the Snake River.
Oregon is to the south, with the Columbia River forming the western part and the 46th parallel forming the eastern part of the Oregon-Washington border. Its northern border lies mostly along the 49th parallel, and then via marine boundaries through the Strait of Georgia, Haro Strait and Strait of Juan de Fuca, with the Canadian province of British Columbia to the north.
Washington has over 1,000 dams, including the Grand Coulee Dam, built for a variety of purposes including irrigation, power, flood control, and water storage.
Washington was named after President George Washington by an act of the United States Congress during the creation of Washington Territory in 1853.
Major factors determining Washington's climate include the large semi-permanent high pressure and low pressure systems of the north Pacific Ocean, the continental air masses of North America, and the Olympic and Cascade mountains.
In the spring and summer, a high pressure anticyclone system dominates the north Pacific Ocean, causing air to spiral out in a clockwise fashion.This causes Washington's prevailing winds, the Chinooks, to come from the southwest, bringing relatively warm and moist air masses and a predictably wet season.The term "Pineapple Express" is used colloquially to describe the extreme form of the wet-season Chinook winds.It includes large areas of semiarid steppe and a few truly arid deserts lying in the rain shadow of the Cascades; the Hanford reservation receives an average annual precipitation of 6 to 7 inches (150 to 180 mm).Farther east, the climate becomes less arid, with annual rainfall increasing as one goes east to 21.2 inches (540 mm) in Pullman, near the Washington-Idaho border.Livestock and livestock products make important contributions to total farm revenue, and the commercial fishing of salmon, halibut, and bottomfish makes a significant contribution to the state's economy.