Southwest Climate Outlook May 2010

Date issued

May Climate Summary

Drought– Drought conditions have continued to improve across the Southwest this past month. Currently, most of southern Arizona and New Mexico are classified as drought-free. However, northeastern Arizona continues to experience moderate to severe drought conditions.
Temperature– The recent shift in the atmospheric circulation has brought cooler than average temperatures to the Southwest. Temperatures in most regions have been 0–4 degrees F below average.
Precipitation– The northward shift in storm tracks has left the Southwest drier than average during the past month. Rainfall in April and May in many parts of the region is, however, usually low.
ENSO– The El Niño event that began in October 2009 has transitioned into ENSO-neutral, which is expected to persist through the summer. However, there are signs that a La Niña event may develop towards the end of summer.
Climate Forecasts– Temperature outlooks show a 50 percent or greater chance that temperatures in the summer and early fall will be above average in most of Arizona and parts of western New Mexico. The precipitation outlooks for summer indicate equal chances of above-, near-, and below-average precipitation.
The Bottom Line– Copious winter precipitation in many parts of the Southwest improved drought conditions. Currently, only about three percent of Arizona is experiencing severe drought conditions or worse, down from 78 percent in mid-January. Only about 12 percent of New Mexico is currently abnormally dry, whereas in mid-January 70 percent of the state was abnormally dry or worse. Drought conditions, however, can rapidly develop if the monsoon season fizzles like it did last year. Early indication is that the monsoon rains will arrive on time or slightly later than usual, but there is no indication that rainfall will be above or below average. If a La Niña event develops in the second half of the summer, which some models suggest, the later half of the monsoon season could experience increased rain.

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.