CW3E Event Summary: 2-8 January 2022

January 10, 2022

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Long Duration Atmospheric River Brings Heavy Rain and Snow to the Pacific Northwest

  • An atmospheric river (AR) made landfall over Southern Oregon on 2 Jan 2022
  • Over the next few days, the AR stalled, strengthened, and tapped into tropical moisture
  • Two mesoscale frontal waves formed along the AR prolonging AR conditions over the region
  • Many areas along the Oregon and Washington coast experienced AR conditions for at least 48 consecutive hours, resulting in AR 3 and AR 4 conditions (based on the Ralph et al. 2019 AR Scale)
  • More than 10 inches of precipitation fell in portions northwestern Oregon, western Washington, and the Cascade Mountains
  • Several river gauges were near or above flood stage; a portion of Interstate 5 was closed due to flooding along the Chehalis River in Lewis County, WA
  • Multiple feet of snow fell across the Cascade Mountains where avalanches and debris forced several mountain passes to close until conditions improved







Summary provided by S. Roj, C. Castellano, J. Kalansky, F.M. Ralph; January 10, 2022

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