The University of Arizona

Climate Snapshot | CLIMAS

 SW Climate Outlook

Climate Snapshot

Dry and warm conditions continued in the Southwest during the last 30 days, upholding a winter-long pattern. Rain or snow did not fall in southern Arizona and most of New Mexico, while the higher elevations of both states were able to squeeze out small amounts of precipitation. Across both states, precipitation deficits since January 1 are large, with most areas experiencing less than 50 percent of average precipitation (Figure 1). The infrequency of cold storms this winter caused snowpacks to be persistently low. While low snowpacks are common for this time of year, they are also below average. This is also the case in the San Juan Mountains of Colorado, which supports streamflows in New Mexico’s most important river, the Rio Grande. Snowpacks there measure only 72 percent of average and contribute to low streamflow projections. The best estimate for inflow into Elephant Butte Reservoir in southern New Mexico, for example, is only 32 percent of average. Snowpacks in Colorado, on the other hand, continue to be above average and best estimates for projected inflows into Lake Mead remain around 110 percent of average. 

Scant rain and warmer-than-average temperatures have caused drought conditions to persist in most of the Southwest in the last month. With the driest months in the Southwest—May and June—approaching, drought conditions will persist until the monsoon starts. The recent dry conditions, coupled with low snowpacks, likely will allow vegetation to dry out faster than normal in coming months, causing longer exposure to fire risk. This may lead to an earlier and longer fire season in most of the Southwest, according to the National Interagency Fire Center (NIFC). Fire risk is also boosted by the above-average 2013 monsoon, which facilitated vegetation growth. Taken together, the NIFC fire forecast calls for elevated chances for above-average significant fire potential, which refers to the likelihood that a wildland fire will require resources from outside the area in which the fire originated (Figure 2).

Significant Wildland Fire Potential - June & July

Looking beyond the fire season, there is increasing evidence that an El Niño event will materialize in the summer or early fall, and experts are leaning toward a moderate or more intense event. Probabilities for an El Niño by the fall exceed 60 percent (Figure 3). This event may also influence the monsoon, providing added moisture into which the monsoon taps, with six of the eight dynamical models calling for above-average precipitation in the May–July period. The monsoon, however, is difficult to forecast. For the winter, an El Niño would favor wetter conditions. 

Seasonal Probabilities for ENSO Phases