Southwest Climate Outlook August 2010

Date issued

August Climate Summary

Drought– Monsoon precipitation helped improve short-term drought conditions across western New Mexico and southeastern Arizona. However, drought expanded across much of western Arizona, where monsoon precipitation has been below average.
Temperature– Cooler-than-average temperatures since the water year began on October 1 continue to prevail in spite of a warmer-than-average summer.
Precipitation– Monsoon storms finally delivered wet conditions to much of Arizona and northeastern New Mexico.
ENSO– The NOAA–Climate Prediction Center has issued a La Niña Advisory, which means that La Niña conditions are present across the equatorial Pacific Ocean and are expected to continue. Many forecast models project either persisting or strengthening La Niña conditions through the fall.
Climate Forecasts– Precipitation outlooks largely reflect the La Niña event currently underway and suggest that the Southwest has a higher probability of experiencing drier-than-average conditions for the remainder of the monsoon season and earlyfall. Temperature forecasts show high probabilities for above-average temperaturesin the next few months.
The Bottom Line– Monsoon rainfall finally picked up in the last 30 days and delivered copious rains to many parts of eastern Arizona and New Mexico, reducing drought conditions in both states. However, the La Niña event became official, and many forecast models predict it will continue through the winter. This will likely reduce winter rain and snow, as storm tracks from the Pacific Ocean will likely follow a more northerly route. While La Niña events often cause drier-than-average winter conditions in Arizona and New Mexico, the Rocky Mountains are not as strongly influenced. Since water levels in Lake Mead are the lowest they have been in 54 years—only 12 feet above the water elevation that triggers rationing—the Colorado River Basin needs a hefty snowpack to mollify water shortage fears.

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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