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Extreme Weather of the Pacific Northwest Cliff Mass University of Washington

Experience the force of the Pacific Northwest's extreme weather, from the strongest non-tropical cyclones to record-breaking rainfall and snowfall. Discover the region's billion-dollar floods, greatest avalanche losses, and localized hurricane-force winds. Dive into the history of intense storms, avalanches, and windstorms that have shaped the Northwest's climate. Uncover the unique weather patterns and challenges faced in this region, including extreme precipitation differences and the impact of atmospheric rivers. Explore the most costly weather events and learn about the Northwest's resilience in the face of nature's fury.

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Extreme Weather of the Pacific Northwest Cliff Mass University of Washington

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  1. Extreme Weather of the Pacific Northwest Cliff Mass University of Washington

  2. The strongest non-tropical cyclones in the nation, with the wind speeds of some equivalent to category 1 or 2 hurricanes. • The greatest annual rainfall in the continental U.S. • World-record snowfalls in our mountains • Billion dollar floods • The greatest avalanche losses in the continental U.S. • Localized hurricane-force winds • and many more … The extreme side of Northwest weather

  3. The force of southerly storms was evident to every eye; large and extensive woods being laid flat by their power, the branches forming one long line to the North West, intermingled with the roots of innumerable trees, which have been torn from their beds and helped to mark the furious course of their tempests. John Meares, 1788, off of Cape Flattery of the Olympics Peninsula

  4. Extreme Northwest Precipitation

  5. Greatest Annual Precipitation in the Continental U.S.

  6. Largest Precipitation Differences Annual Precipitation

  7. SW Olympic Slopes-Hoh Rain Forest: 150-170 inches yr-1

  8. Sequim: Haven for Retirees 15 inches a year—similar to LA!

  9. The NW region has extreme differences in annual precipitation

  10. Why such extremely dry summers? Few thunderstorms Fewer thunderstorms!

  11. Greatest Annual Snowfall Totals in the World! The Mt. Baker Ski Area in northwestern Washington State reported 1,140 inches of snowfall for the 1998-99 snowfall season

  12. The most costly extreme weather of the Northwest: Flooding

  13. Most are associated with the “Pineapple Express” A relatively narrow current of warm, moist air from the subtropics…often starting near or just north of Hawaii. a.k.a. Atmospheric rivers

  14. A Devastating Pineapple Express: November 6-7, 2006 Dark Green: about 20 inches

  15. Mount Rainier National Park18 inches in 36 hr (Nov 8, 2006)

  16. Dec. 3, 200720 inches in two days over coastal terrain of SW Washington The results: massive landslides and river flooding

  17. Sometimes damaging NW rains are very localizedThunderstorms and narrow valleys Heppner, Oregon June 14, 1903

  18. Extreme Winds

  19. The region’s most extreme winds are associated with strong Pacific Cyclones Inauguration Day Storm January 29, 1993 1993 Inauguration Day Storm

  20. Trees—our force multiplier

  21. Much more damaging than wimpy tropical palms

  22. The Most Extreme Northwest Windstorm: The Columbus Day Windstorm of 12 October 1962

  23. Max Winds (mph) Columbus Day Storm 1962 Probably the most intense non-tropical cyclone to hit the continental U.S. in a century

  24. Columbus Day 1962: At Cape Blanco there were 150 mph with gusts to 179. Strongest winds on bluffs and windward slopes of coastal orography

  25. The Great Coastal Gale of December 3-4, 2007 A very unusual windstorm Hurricane-force winds sustained for nearly 24-h Flooding over the coastal mountains

  26. Near Route 26 in Oregon

  27. Extreme Local Winds

  28. February 13 1979: The Hood Canal Storm Winds over 110 mph destroyed the Hood Canal Bridge Cost to replace: over 100 million dollars

  29. The Hood Canal Storm

  30. February 13 1979: The Hood Canal Storm Intense pressure gradient led to strong winds

  31. Extreme Winds are Also Observed Downstream of Gaps Example: Fraser River Gap Winds

  32. Fraser River Gap Windstorms December 28, 1990

  33. Max Winds, 28 Dec. 1990 Fraser River NE Gap Flow Gusts above 90 mph December 28, 1990

  34. Enumclaw and nearby foothills locations can experience severe windstorms…while calm winds occur a dozen miles away Winds over 118 mph December 24, 1983

  35. December 24, 1983

  36. Why Enumclaw?

  37. Enumclaw Windstorm Pressure Pattern December 28, 1990 December 24, 1983

  38. Extreme Avalanches • The greatest loss of life from an avalanche occurred in Washington State • Wellington WA disaster, March 1, 1910 • 96 people killed in a train going across Stevens Pass • Heavy snow followed by heavy rain *

  39. Even today, avalanches are major problems in our region

  40. And didn’t even mention many other extreme weather effects of the region! • Extreme freezing rain in and downstream of the Columbia Gorge and eastern Washington • Massive wildfires in certain meteorological conditions • The greatest rain-caused slope failure in US history.

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