CW3E AR Update: 5 November 2021 Outlook

November 5, 2021

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Model Forecasts Show Potential for Another Strong AR in California Next Week

  • A weak atmospheric river (AR) made landfall along the US West Coast this morning and will continue to impact Northern California, Oregon, and Washington through tomorrow
  • A stronger AR is forecasted to make landfall across California next week, but there is considerable uncertainty in the timing, duration, and magnitude of AR conditions
  • The 00Z GEFS control run is forecasting an AR 3 near Point Reyes, CA, and AR 1/AR 2 conditions elsewhere along the coast in Central and Northern California
  • The 00Z ECMWF EPS control run is forecasting an AR 2 in the San Francisco Bay Area and AR 1 conditions elsewhere in Central and Northern California
  • The second AR is forecasted to bring 2–4 inches of precipitation to the higher terrain in Northern California
  • There is also potential for significant snowfall accumulations in the Cascades and Sierra Nevada

Click images to see loops of GFS IVT & IWV forecasts

Valid 1200 UTC 5 November – 1200 UTC 10 November 2021










Summary provided by C. Castellano, J. Kalansky, B. Kawzenuk, and F. M. Ralph; 5 November 2021

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