CW3E AR Update: 9 October 2020 Outlook

October 9, 2020

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Update on Atmospheric Rivers Forecast to Impact the Northwestern US

  • Multiple landfalling ARs are forecast to bring significant precipitation to the northwestern US during the next 7 days
  • Current forecasts suggest that AR 3/AR 4 conditions (based on the Ralph et al. 2019 AR Scale) are possible over coastal Oregon and Washington in association with the first and third ARs
  • Inland penetration of these ARs may also produce AR 2/AR 3 conditions over portions of interior Oregon and Washington
  • 7-day total precipitation is forecast to exceed 7 inches over the Olympic Mountains and North Cascades, with more than 3 inches of precipitation possible over the Northern Rockies

Click images to see loops of GFS IVT/IWV analyses and forecasts

Valid 1200 UTC 9 October – 1200 UTC 17 October 2020







Summary provided by C. Castellano, J. Kalansky, B. Kawzenuk, and F. M. Ralph; 9 October 2020

*Outlook products are considered experimental