Southwest Climate Outlook July 2010

Date issued

July Climate Summary

Drought– Drought conditions expanded in Arizona in the last month and remained steady in New Mexico. About 58 percent of Arizona is experiencing abnormally dry conditions or worse, up from about 36 percent one month ago; about 50 percent New Mexico is abnormally dry or worse.
Temperature– The absence of moisture and thunderstorms is causing extreme daytime temperatures across the Southwest.
Precipitation– Dry conditions continue as monsoon storms have been few and far between. Most of Arizona has received 25 percent of average precipitation; northwestern New Mexico has been the driest part of the state, while southern portions have experienced above-average rainfall.
ENSO– Atmospheric and oceanic conditions are set for the development of a La Niña event during the July–August period. Forecasts indicate an approximately 80 percent chance that La Niña conditions will occur for the July–September period and persist through the remainder of 2010.
Climate Forecasts– Forecasts call for the remainder of the monsoon season and early fall to be warmer and drier than average with below-average precipitation for August–October for most of Arizona and the western half of New Mexico.
The Bottom Line– It has been a dry and warm start to the monsoon season. Most of Arizona and western New Mexico have experienced less than 50 percent of average precipitation. As a result, drought conditions have cropped up in southeastern Arizona, which typically receives the brunt of monsoon moisture in the state. Looking ahead, NOAA–CPC has downgraded its outlook for the monsoon season precipitation from equal chances to below average. This doesn’t bode well for drought conditions, because the La Niña that likely will take shape in July or August also will likely decrease fall and winter precipitation. If the monsoon season fizzles like it did last year, the Southwest could experience rapidly expanding drought conditions.

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.

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