Precipitation

Precipitation across most of Arizona and New Mexico during the 2012 water year was below average (Figures 2a–b). Precipitation deficits ranged from 0 to 8 inches in most regions of both states and up to 12 inches in a few locations in northern New Mexico. Deficits in Flagstaff were more than 6 inches (Table 1). There were a few exceptions in western Arizona. Above-average precipitation fell in central Mohave County, for example, bolstered by a few wet monsoon storms, and western Pima County also benefited from a few strong monsoon storms as well as a large winter storm. Departures from average precipitation can be misleading. Small departures may not seem significant, but in arid environments like the desert Southwest, a 2-inch rainfall deficit may equate to a 25- to 50-percent decrease in rainfall.

The La Niña event, which began in September 2011 and persisted through April 2012, helped push most storms north of Arizona and New Mexico. The winter was followed by an active monsoon that tended to favor the western half of Arizona, leaving eastern Arizona and most of New Mexico very dry. Southwestern Maricopa County and the Four Corners area have been the two driest locations in Arizona, as both winter and summer storm activity bypassed them. In New Mexico, precipitation in eastern regions has been less than 70 percent of average in the last 12 months. In the southwestern corner of the state, scant monsoon rainfall contributed to precipitation amounts of less than 50 percent of average. Overall, the below-average rain and snow in Arizona and New Mexico helped sustain drought conditions, which are both widespread and intense across the region. All of the Southwest is currently experiencing at least moderate drought, with severe and extreme conditions covering the areas that have experienced the driest conditions in the last year.
 

Click figures to enlarge.

Table 1. Water Year 20 precipitation values (in inches) for select cities.

City	WY 2012 Precip.	Average WY Precip.	2012 Departure from Avg.	2011 Departure from Avg.
Phoenix, AZ	5.38	8.03	-2.56	-3.56
Tucson, AZ	9.76	12.17	-2.41	-2.08
Douglas, AZ	9.17	13.76	-4.59	-6.64
Albquerque, NM	8.04	9.47	-1.43	-6.21
Winslow, AZ	6.95	8.03	-1.08	-1.99
Flagstaff, AZ	16.73	22.91	-6.18	-0.09
Yuma, AZ	3.92	3.05	+0.87	-1.38
El Paso, TX	6.81	9.43	-2.62	-4.80

 

Notes: