Southwest Climate Outlook December 2011

Date issued

December 2011 Climate Summary

Drought-Drought conditions in Arizona and New Mexico have improved slightly as a result of several early winter storms. Drought conditions remain widespread, however, due to significant precipitation deficits that have accumulated since the start of last winter.

Temperature-Temperatures have been colder than average in the last 30 days, but near average since the water year began on October 1.

Precipitation-Several winter storms tapped subtropical moisture and moved across Southern California and into Arizona and New Mexico in the past 30 days. As a result, many areas have received more than 150 percent of average rain and snow.

ENSO-Weak to moderate La Niña conditions persist in the tropical Pacific Ocean. Forecasts suggest the event will peak in January or February, with half of the models suggesting it will increase to moderate intensity.

Climate Forecasts-Seasonal precipitation outlooks call for drier-than-average conditions through April in New Mexico and Arizona, with southern regions drier than northern areas. Temperature outlooks call for increased odds of warmer-than-average conditions in New Mexico in the next three months.

The Bottom Line-A weak to moderate La Niña event remains entrenched in the tropical Pacific Ocean and continues to influence below-average precipitation outlooks for the winter. However, several wet and cold early winter storms moved through the region, dumping rain and snow in the Southwest that improved drought conditions in some areas. These storms tapped tropical moisture and chilly polar air, creating ripe conditions for snow to fall at mid-elevations. However, these storms missed the southeast corner of New Mexico, where precipitation in the last month has been below 75 percent of average. Exceptional and extreme drought continue to grip this region. The atmospheric circulation that ferried several early winter storms into the Southwest is somewhat abnormal for a La Niña, which often pushes storms north of the region this time of year. However, weak La Niña events tend to be wetter than moderate or strong events. 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.

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.