2020 North American Monsoon Recap

October 22, 2020

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2020 North American Monsoon season characterized by extreme heat and lack of rainfall

  • The North American Monsoon (NAM) refers to a shift in the synoptic-scale wind pattern that transports low-to-midlevel moisture from the Eastern Pacific, Gulf of California, and Gulf of Mexico into the southwestern US during summer
  • The NAM is an important source of annual precipitation for parts of the southwestern US
  • Unlike the stronger Indian Monsoon, the NAM is characterized by episodic bursts of moisture transport and rainfall
  • Persistent circulation anomalies during July–September 2020 resulted in an abnormally inactive monsoon season
  • The Southwest climate region experienced its warmest and driest July–September period on record
  • Anomalously warm and dry summer weather further exacerbated existing drought conditions over the western US







Summary provided by C. Castellano, J. Cordeira, J. Kalansky, N. Oakley, and F. M. Ralph; 22 October 2020