CW3E Event Summary: 16-18 November 2020

November 20, 2020

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Powerful storm and AR bring rain, snow, and wind to the Western U.S.

  • A landfalling AR associated with a surface cyclone over the Northeast Pacific Ocean impacted the Pacific Northwest and Northern California during 16–18 Nov
  • Coastal Oregon and Washington experienced AR 3/AR 4 conditions (based on the Ralph et al. 2019 AR Scale)
  • About 2–5 inches of precipitation fell over the Pacific Coast Ranges, Cascades, and Northern Sierra Nevada, with locally higher amounts in the Olympic Mountains and North Cascades
  • Snowfall accumulations exceeded 12 inches in portions of the Cascades, Sierra Nevada, and Rocky Mountains
  • Strong winds caused minor coastal flooding and scattered power outages in Washington and Oregon

Click images to see loops of GFS IVT/IWV analyses

Valid 0000 UTC 16 November – 1200 UTC 20 November 2020

Summary provided by C. Castellano, C. Hecht, B. Kawzenuk, N. Oakley, and F. M. Ralph; 20 November 2020