Southwest Climate Outlook September 2014

Date issued

Precipitation: In the past 30 days, monsoon activity brought above-average precipitation to much of Arizona and New Mexico. But despite large-scale patterns of above-average overall precipitation, the coverage was not universal. Certain areas, such as the Four Corners region, continue to suffer from both short-term drought and accumulated water deficits (longer-term drought). Tropical storm systems complicated the precipitation picture, affecting the accumulated totals by producing record or near-record rainfall and causing widespread flooding.

Temperature: Monsoon storms continue to drive temperature variability on a day-to-day basis, but over the past 30 days, most of Arizona saw slightly below-average temperatures while New Mexico was closer to average temperatures.

Water Supply: In Arizona, total reservoir storage dropped by about 135,000 acre-feet (AF) in August, putting total reservoir capacity at 46 percent (compared to 48 percent last year). In New Mexico, the total reservoir capacity in August was 26 percent, compared to 16 percent last year. Lake Mead continues to receive attention as concerns over drought and water supply persist, and Lakes Mead and Powell are both running well below maximum capacity (39 and 51 percent, respectively). Despite substantial rainfall as part of monsoon and tropical systems, the spatial variability of these storms means they have done little to mitigate the effects of long-term drought on regional water supplies.

Drought: Above-average monsoon precipitation in conjunction with moisture from tropical storm events reduced the scale and extent of short-term drought conditions; long-term drought conditions persist throughout Arizona and New Mexico.

Monsoon: The monsoon has been strong in Arizona and New Mexico, with most of Arizona and much of New Mexico receiving above-average precipitation. Widespread areas received over 100 percent of average precipitation, with a large subset receiving 150-200 percent of average, and smaller areas have even seen 200-400 percent of average precipitation. The notable exceptions to this pattern are in the Four Corners region, northeastern New Mexico, and portions of Pinal and Pima counties in Arizona. A caveat applies to many of the higher measurements, given that in a number of cases, storms dropped an entire month’s or year’s worth of precipitation in a single storm event. Such occurrences drastically increase the overall totals for the year, but these intense storms do not provide the same kind of drought relief as steadier and more consistent precipitation, not to mention their destructive potential (see the SW climate podcast from Aug 2014 for details).

ENSO: El Niño remains in a holding pattern as ENSO-neutral conditions persist. The projections remain at a 65 to 70 percent probability for the development of an El Niño event, with most projections pointing towards a weak-to-moderate event if and when one develops. A strong event is widely thought to be off the table.

Precipitation & Temperature Forecasts: Longer-term forecasts point toward above-average precipitation for Arizona and New Mexico, especially if an El Niño event eventually develops. As we approach fall and winter, the prospect of an El Niño event, regardless of strength, suggests an increased probability of below-average temperatures for the Southwest.

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.