Monsoon Summary

High water content was present in the atmosphere for most of the monsoon in Arizona, which has been the pattern in recent years. The dew point temperature, which is a measure of water in the atmosphere, was predominantly at levels that favored storms across Arizona this summer. As a result, most of the state experienced an active 2012 monsoon, particularly southern areas and the Mogollon Rim, which received above-average rain (Figure 8a). Rain in many parts of these regions measured between 6.5 and 8.5 inches between June 15 and September 12 (Figure 8b), with the greatest departures from average occurring in western Arizona (Figure 8c). In this region, several surges from the Gulf of California helped fuel intense storms. Yuma, for example, received 2.25 inches of rain—0.96 inches more than average. High moisture content and other favorable conditions led to rainfall that measured 6.02 and 3.00 inches at the Tucson and Phoenix airports, respectively, which is 0.37 and 0.29 inches above their historical average. While the position of the subtropical high pressure, which was centered predominantly over New Mexico, allowed moist air to waft into Arizona from the southeast, it also prevented incursions of damp air into New Mexico. There, the high pressure brought clear, cloudless skies for much of the monsoon, and nearly all of the state received below-average rainfall. Many parts of eastern New Mexico received less than 70 percent of their historical average. While the dry conditions did not expand drought conditions in New Mexico in the last three months, they also did not help improve conditions. Currently, nearly all of eastern New Mexico is experiencing severe and extreme drought.