CW3E AR Update: 11 January 2021 Outlook

January 11, 2021

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Strong atmospheric river to impact the Pacific Northwest this week

  • A strong and zonally elongated atmospheric river (AR) is forecast to make landfall across Washington, Oregon, and Northern California today
  • AR 4 conditions (based on the Ralph et al. 2019 AR Scale) are possible over coastal Oregon and Washington
  • At least 3–7 inches of precipitation are expected in the Pacific Coast Ranges and Cascades
  • More than 2 feet of snow is forecast in the higher terrain of the Olympic Mountains and Washington Cascades
  • Intense precipitation falling in areas with saturated soils and existing burn scars from the 2020 wildfires may result in flooding and debris flows in western Washington and Oregon

Click images to see loops of GFS IVT & IWV forecasts

Valid 0600 UTC 11 January – 0600 UTC 15 January 2021









Summary provided by C. Castellano, C. Hecht, J. Kalansky, N. Oakley, and F. M. Ralph; 11 January 2021

*Outlook products are considered experimental