CW3E Event Summary: 9-13 March 2020

March 17, 2020

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Cutoff low and landfalling AR bring heavy rainfall to the southwestern U.S.

• A quasi-stationary cutoff low interacted with a region of tropical moisture over the Eastern Pacific Ocean, resulting in a long-duration atmospheric river (AR) over the Baja Peninsula
• Poleward moisture transport and strong synoptic-dynamic forcing for ascent produced multiple episodes of heavy rainfall across Southern California, Arizona, and southern Nevada
• Elevated sections of Southern California and central Arizona received 3–6 inches of total precipitation, with 1–3 inches at lower elevations

Click IVT or IWV image to see loop of GFS analyses Valid 0000 UTC 9 March – 0000 UTC 14 March 2020

Summary provided by C. Castellano and F. M. Ralph; 17 March 2020