Monsoon Summary

Monsoon storm activity slowed down a bit this past month as the heat dome of high pressure that has been scorching the Great Plains shifted back west towards Arizona and New Mexico. With high pressure nearly overhead, high temperatures soared to record and near-record temperatures across the Southwest in early August and limited the development of widespread thunderstorm activity.  

Areas receiving the most monsoon precipitation so far this season (June 15 to August 13) include higher elevation areas along the Mogollon Rim in Arizona, southeast Arizona, and the southern Rockies in western New Mexico (Figures 9a–c). Extreme southern Arizona in Santa Cruz County has received rainfall totals of more than 8 inches, which is close to 150 percent of average for this period.

Across southern Arizona, Nogales is the big winner, receiving almost 9 inches of monsoon rain so far this year, which is almost 2 inches above average. Totals in Tucson and Sierra Vista through August 17 are also above average. Tucson has received 4.64 inches–0.87 inches more than average—while Sierra Vista has received 6.04 inches, about 0.34 inches above average. Organ Pipe National Monument in far southwestern Arizona and Douglas in the far southeastern part of the state have fallen behind in 2012 monsoon precipitation totals. Douglas, in particular, has received only half of the 5 inches of rain that should have fallen so far this season. For more rainfall statistics in Arizona, visit: http://www.wrh.noaa.gov/twc/monsoon/rainfall.php.