April 2012 Climate Summary
Drought: Moderate or more severe drought covers most of Arizona and New Mexico. Central and southern Arizona and eastern New Mexico are the only areas in the West classified with extreme or exceptional drought.
Temperature: Temperatures across most of the Southwest in the last 30 days were 2 to 6 degrees F warmer than average.
Precipitation: Precipitation in most of Arizona and southern and western New Mexico measured less than 50 percent of average in the last 30 days, continuing a dry stretch that began around January 1.
ENSO: The La Niña event is transiting to ENSO-neutral conditions; neutral conditions are expected to persist through the May–July. Signs of a developing El Niño are on the horizon.
Climate Forecasts: Forecasts call for above-average temperatures through the monsoon. Precipitation forecasts, however, are less definitive, as monsoon forecasts historically have been about as accurate as a coin flip.
The Bottom Line: Had it not been for the cavalcade of storms that drenched many parts of Arizona and New Mexico in December 2011, precipitation deficits would be much higher across the Southwest. Since January 1, rain and snow have measured less than 50 percent of average across the region, and it has been similarly dry in the Upper Colorado River and Rio Grande basins. In these regions, snowpacks are below average and most stations report that the water contained in snowpacks is less than 50 percent of average. The scant snow this winter is feeding low spring streamflow projections across the region. Inflow into Lake Powell, for example, is expected to be 3.5 million acre-feet less than average, or 44 percent of average. Relief from expanding and intensifying drought may not come until the monsoon begins this summer, but it is unclear when the monsoon will begin in earnest or how much rain it will deliver. Although monsoon forecasts are not definitive, there is higher confidence that temperatures will be above average in coming months, in part because summer months have become progressively warmer in recent decades.