Forecasts and Outlooks > Archive
Southwest Climate Outlook - August 2003

Date issued: August 25, 2003

A. Summary

Hydrological drought continues to be a major concern for the Southwest. Most New Mexico river basins remain in emergency drought status, and reservoir storage in the Rio Grande and Pecos Basins is likely to decline by the end of summer. Groundwater levels in many parts of New Mexico continue to decline. Current storage has continued to decrease in most Arizona reservoirs.

Summer monsoon rainfall has displayed great geographic variation across the Southwest. Most of New Mexico has had a very dry summer, as has southeastern Arizona. Parts of western and north-central Arizona have received average to above-average precipitation this summer.

Fire danger is above average only across south-central and eastern New Mexico. Monsoon rains have eased fire danger over most of our region, but in some areas of New Mexico fuel moisture remains at historically dry levels.

New Mexico and Arizona continue to have exceedingly poor range and pasture conditions (relative to state averages) in the United States.

Seasonal temperature forecasts indicate increased probabilities of above-average temperatures across Arizona and most of New Mexico through the winter months. Seasonal precipitation forecasts indicate slightly decreased probabilities of below-average precipitation across Arizona and western New Mexico this fall.

Equatorial Pacific sea surface temperatures have increased slightly, but, overall, ENSO conditions are neutral, and are expected to remain neutral for the rest of 2003.

Bottom line: Hydrological drought will continue in the Southwest during the next several months, and New Mexico water supplies will continue to decline at least until the end of the summer.

The most likely scenario is that the remainder of our summer rainfall will be below average over most of the region, with some areas of above-average rainfall in parts of Arizona and in northeastern New Mexico. Summer rainfall tends to have minimal impact on reservoirs. Neutral equatorial Pacific Ocean temperatures are expected to persist beyond the summer. The autumn tropical storm season will be a wildcard.

The worst case scenario is that summer monsoon precipitation tapers off rapidly and autumn conditions are abnormally hot and dry across the region. The aforementioned scenario might result in renewed fire danger, high evaporation rates, and decreased reservoir and groundwater levels.

The best case scenario is that El Niño rebounds this fall and winter, providing increased chances of above-average precipitation. Sea-surface temperature trends are not yet clear enough, however, to assess the likelihood of this scenario.

B. Recent Conditions >