CW3E Event Summary: 11-17 December 2020

December 18, 2020

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Active Weather Pattern Brings Multiple Episodes of Rain and Snow to the Western U.S.

  • Several ARs associated with a series of cyclones over the Northeast Pacific Ocean have impacted the Western U.S. during the past 7 days
  • These storms produced at least 2–5 inches of total precipitation in the Sierra Nevada, Cascades, and Pacific Coast Ranges, and lighter amounts across the Intermountain West
  • An estimated 1–3 feet of snow fell in the higher terrain of the Sierra Nevada, Cascades, and northeastern Nevada
  • Total water-year-to-date precipitation remains well-below normal across much of California

Click images to see loops of GFS IVT/IWV analyses

Valid 0000 UTC 11 December – 0000 UTC 18 December 2020






Summary provided by C. Castellano, C. Hecht, J. Kalansky, B. Kawzenuk, and F. M. Ralph; 18 December 2020