Southwest Climate Outlook October 2012 Water Year in Review

Date issued

The 2012 Water Year in Review is a summary of the information presented in the Southwest Climate Outlook between October 1, 2011, and September 30, 2012. The water year is a standard period of measurement used in hydrology because the natural seasonal ground recharge and discharge cycles are more aligned with the October–September period than the calendar year due to precipitation and evaporation patterns. This review highlights precipitation, temperature, reservoir levels, drought, wildfire, and El Niño-Southern Oscillation (ENSO) conditions over this 12-month period.

Heat and drought defined the water year, smothering the Midwest, in particular, during the spring and early summer. Temperatures during the water year were among the top five warmest on record in 39 of the 48 contiguous states, ranking as the 19th and fifth warmest on record in Arizona and New Mexico, respectively, out of 117 years. These conditions conspired with scant precipitation to cause many of the nation’s fertile farmlands to wilt.

Warmer-than-average temperatures and below-average precipitation across nearly all of Arizona and New Mexico characterized the water year. Consequently, moderate or more severe drought covers almost the entire Southwest and drought conditions are now more widespread, though less intense, than they were at the beginning of the water year. The fact that drought has persisted in many parts of the Southwest during the last two years is not surprising given the occurrence of a La Niña event during back-to-back winters; La Niña conditions often deflect winter storms north of the Southwest. It was also a relatively dry winter in the headwaters of the Colorado River and Rio Grande in Colorado, where scant rain and snow contributed to storage declines in many reservoirs on these rivers. Dry conditions also set the stage for wildland fires in the Southwest. Although this water year’s fire season did not surpass the record number of acres burned last year, New Mexico’s largest wildland fire on record—the Whitewater-Baldy Complex fire—tore across 298,000 acres in the west-central part of the state in and around the Gila National Forest, nearly doubling the size of the state’s previously largest fire.

Published by the Climate Assessment for the Southwest (CLIMAS), with support from University of Arizona Cooperative Extension, the Arizona State Climate Office, and the New Mexico State Climate office.

Disclaimer. This packet contains official and non-official forecasts, as well as other information. While we make every effort to verify this information, please understand that we do not warrant the accuracy of any of these materials. The user assumes the entire risk related to the use of this data. CLIMAS, UA Cooperative Extension, and the State Climate Office at Arizona State University (ASU) disclaim any and all warranties, whether expressed or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will CLIMAS, UA Cooperative Extension, and the State Climate Office at ASU or The University of Arizona be liable to you or to any third party for any direct, indirect, incidental, consequential, special or exemplary damages or lost profit resulting from any use or misuse of this data.