CW3E AR Update: 10 November 2021 Outlook

November 10, 2021

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Multiple atmospheric rivers are forecast to bring moderate to strong AR conditions to the Pacific Northwest

  • The first AR is forecast to make landfall over coastal Washington tomorrow, bringing AR 4 conditions to much of the Coast
  • Current precipitation forecasts indicate that this first AR could bring more than 5 inches of precipitation to the Cascade, Olympic, and Coastal Mountains in Oregon and Washington
  • A second AR is forecast to make landfall over the Olympic Peninsula during the weekend
  • There is currently large model uncertainty pertaining to the timing, maximum intensity, and overall duration of the second AR, though several GEFS ensemble members are predicting AR 4 conditions for South-Coastal Washington
  • In total, the Coastal, Olympic, and Cascade Mts. could receive >7 inches of precipitation during the next 7-days

Click images to see loops of GFS IVT & IWV forecasts

Valid 1200 UTC 10 November – 1200 UTC 20 November 2021







Summary provided by C. Hecht, C. Castellano, Shawn Roj, J. Kalansky, B. Kawzenuk and F. M. Ralph; 10 November 2021

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