Floods, mudslides and avalanches in the Pacific Northwest kept thousands of people from their homes Thursday. The flooding, which is some of the worst on record in Washington state, was started by a combination of heavy rain of 6 inches or more and a warm spell in the 50s that rapidly melted the snow in the Cascade Mountains. Hundreds of truckers pulled their rigs off onto the shoulders of the road as the bad weather stopped nearly all freight in and around Seattle, costing the local economy millions of dollars a day. Nearly 40,000 people in western Washington were urged to evacuate their homes late Wednesday in low-lying areas from Bellingham near the Canadian border to the Kelso area near the Oregon line as rivers spilled over their banks and flooded neighborhoods.