CW3E AR Update: 9 April Summary

April 9, 2019

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Summary of the atmospheric river that impacted Oregon and Northern California between 6 and 9 April 2019

• A strong and long duration AR made landfall over Oregon and Northern California during 6–9 April 2019
• Numerous locations across Northern California and Southern Oregon received >5 inches of precipitation over 72 hours with multiple gauges recording >10 inches
• The maximum three day total was 365 mm, or 14.58 inches. The max including a couple of days earlier reached over 17 inches.
• The AR resulted in AR Category 4 conditions over Southern Oregon, a lightly populated region
• Ten river gauges in OR and WA exceeded flood stage, and many others reached action level or bankfull.
• The landfall and limited southward propagation of the AR resulted in a large north-south gradient in precipitation accumulations between Del Norte and southern Humboldt Counties in Northern California

Images from CIMSS/Univ. of Wisconsin

Click IVT or IWV image to see loop of GFS Analysis Valid 0000 UTC 5 April – 0600 UTC 9 April 2019

Summary provided by C. Hecht, B. Kawzenuk, and F. M. Ralph; 4 PM PT 9 April 2019