CW3E AR Update: 17 November 2017 Outlook and Summary

November 17, 2017

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Strong AR recently made landfall over northern California

• The AR reached its strongest magnitude of ~750 kg m^-1 s^-1 at ~6 PM PST over northern California making this a strong AR
• IWV values within the AR ranged from 34–40 mm during the event
• A second AR is forecast to make landfall over the USWC between 19 and 21 November 2017
• The AR is currently over Southern California bringing precipitation to the Los Angeles area
• Another AR is forecast to impact the USWC in the next several days

Images from CIMSS/Univ. of Wisconsin

Click IVT or IWV image to see loop of GFS Analysis Valid 0000 UTC 15 November – 1200 UTC 17 November 2017

A potentially extreme AR is forecasted to make landfall over the U.S. West Coast next week

• The current AR impacting Southern California is forecast to end by later tonight
• Multiple systems are forecast to bring potentially strong to extreme and prolonged AR conditions to the USWC
• As much as 19 inches of precipitation could fall over the Olympic Mountains over the next week
• Multiple rivers in Washington are currently forecast to rise above flood stage

Click IVT or IWV image to see loop of 0-180 hour GFS forecast Valid 1200 UTC 17 November – 0000 UTC 25 November 2017

Summary provided by C. Hecht, B. Kawzenuk, J. Kalansky, and F.M. Ralph; 3 PM PT Friday 17 November 2017

*Outlook products are considered experimental