Monsoon Summary

The first two months of the monsoon season have been underwhelming and spottier than normal in many parts of Arizona and New Mexico despite persistant high humidity. Although moisture has been present, a lack of strong winds aloft and atmospheric stability has prevented widespread and constant rains. As a result, rainfall between June 16 and August 14 in New Mexico and Arizona generally has been less than 3.5 inches, with precipitation deficits ranging from 1.5 to 4.5 inches in New Mexico (Figures 9a–b). Rainfall has measured less than 75 percent of average in most of New Mexico, with the driest conditions occurring in the southeast corner (Figure 9c). Only parts of southeast and southwest Arizona and the Four Corners region have experienced above-average rainfall. The drier-than-average conditions in New Mexico can be blamed in part on the position of the subtropical high, or the monsoon ridge, which has hovered too far to the east to deliver copious rains to most of the state. This extensive dome of high pressure has generally extended from the East Coast to eastern New Mexico, causing winds over New Mexico to waft generally from the east instead of the south. The drier-than-average conditions have not helped improve widespread and intense drought for most of the region. On August 16, 12 and 77 percent of Arizona and New Mexico, respectively, were pegged with extreme or exceptional drought. Two months earlier, at the onset of the monsoon season, those numbers were 18 and 68 percent.