Precipitation

Precipitation since the water year began on October 1 generally has been between 50 and 70 percent of average in Arizona and southern and eastern counties of New Mexico (Figures 2a–b). Maricopa and Mohave counties and northern Apache County have been particularly dry, measuring less than 50 percent of average. Most of Southern California also has seen scant rain and snow. The cause of the dry weather in Arizona and California has been the position of the storm track. Generally, storms have either moved south into Mexico before wafting northeast through New Mexico, or they have tracked through Nevada and Utah before dropping down into New Mexico. Both of these trajectories have been a boon to northern and central New Mexico, however, as precipitation there has been between 100 and 300 percent of average.

 
In the past 30 days, only two winter storms passed through Arizona. The first dumped precipitation across the northern counties in Arizona and northwestern New Mexico, while the other wafted south into Mexico, dropping precipitation on the southeast corner of Arizona and the southwest corner of New Mexico. Most of the Southwest experienced precipitation totaling less than 75 percent of average, but several areas received well-above average rain and snow. The high variability in the past month—from 2 percent of average in many areas to more than 400 percent of average in others—is not unusual during La Niña winters. La Niña events tend to bring drier, more variable conditions, while El Niño events often more consistently deliver wet conditions.