Southwest Climate Outlook September 2011

Date issued

September 2011 Climate Summary

Drought– Monsoon precipitation during the past 30 days provided some drought relief to parts of New Mexico and Arizona, but overall moderate drought or a more severe category persists across most of the region and even expanded and intensified across parts of Arizona.

Temperature–Record warmth, continues across the Southwest. Temperatures have been 2–4 degrees F above average throughout most of the region.

Precipitation– The monsoon ramped up in mid-September, delivering copious rain to many parts of the Southwest; the monsoon as a whole, however, has delivered below-average precipitation.

ENSO– La Niña is back and is expected to deliver below-average precipitation to much of Arizona and New Mexico through the upcoming fall and winter seasons.

Climate Forecasts–Seasonal climate outlooks call for above-average temperatures through the new year, while below-average rainfall is forecasted for this winter.

The Bottom Line–The monsoon is nearly over and extreme and exceptional drought conditions remain ensconced in the region, particularly in the southeastern corners of Arizona and New Mexico. Widespread and intense monsoon storms flared up for a week in mid-September, but the total amount of rainfall since June 15 has been slightly below average for most of the region. Scant rain in some parts of the Southwest in conjunction with region-wide, warmer-than-average temperatures caused drought to expand and intensify in Arizona. The Southwest likely will continue to experience drier-than-average conditions because a La Niña event officially has returned. There is uncertainty about how long and how strong this La Niña will be, but forecasts suggest at least a weak event will persist through the winter.

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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