Dry and warm conditions continue in the Southwest in the past 30 days. Temperatures in Arizona were between 2 and 6 degrees F above average, with the largest temperature anomalies occuring in the southwest region of the state (Figure 1). New Mexico had similarly warmer-than-average conditions in the past 30 days. Averaged over the January–February period, Arizona temperatures were the warmest on record, a period that spans 120 years, according to the National Climatic Data Center. While not record setting, New Mexico experienced its 13th warmest January–February on record. During these months, a persistent high-pressure system parked off the West Coast pushed the jet stream north of the Southwest, causing warm temperatures and stifling rain and snowfall. Precipitation averaged over January and February was the fourth driest and driest on record in Arizona and New Mexico, respectively. While the high-pressure system in the last month was not been as persistent as in previous months, only one storm wafted over the region, occuring around March 1, and precipitation was less than 50 percent of average across most of Arizona and New Mexico. Consequently, drought remains widespread and intense in both states. The lack of precipitation also increased the potential for large wildfire risk from April to July. Barring a few late winter storms, drought conditions are not expected to improve before the monsoon.
The warm and dry conditions in Arizona and New Mexico have resulted in low snowpacks across the region (Figure 2) and in expectations for low spring and summer streamflows. For example, forecasts for the Salt, Verde, and Gila rivers in Arizona call for streamflows to be around 24, 52, and 28 percent of the March–May average, respectively. Because the majority of winter precipitation falls before the end of March, these forecasts are relatively accurate. In New Mexico, the Rio Grande is also expected to have very low streamflow, which will further exacerbate water stress for urban, agriculture, and other uses. Currently, Elephant Butte Reservoir is only 15 percent full. While Arizona and New Mexico have been drier than average, the Colorado mountains have received above-average snow, and the Colorado River streamflow forecast calls for inflow into Lake Powell to be around 109 percent of average.
Forecasts for upcoming months call for high probabilities of above-average temperatures, an expectation based in part on warming trends in recent decades. There is also increasing evidence that an El Niño event will form in coming months if a large pool of warm water below the sea surface continues to migrate east. The next several months will be pivotal for an El Niño formation. If an El Niño materializes, it will be the first one since 2009 and it could alter monsoon and winter weather patterns in the Southwest.