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Published September 20, 2011
Precipitation(data through 9/14/11)
Data Source(s): High Plains Regional Climate Center
Precipitation since the water year began on October 1 ranges from more than 130 percent of average in the northwest corner of Arizona to less than 25 percent of average in the southeastern corner of New Mexico (Figures 1a–b). Most of Arizona and northwestern New Mexico have received 25–90 percent of average precipitation. The southeastern half of New Mexico, however, has received less than 50 percent, with the driest conditions occurring in the southeastern corner. The dry conditions began in the winter during the moderate to strong La Niña event that helped push storms to the north. For most of the Southwest, monsoon precipitation has been below average. The exceptions have been in southeastern Arizona and the Four Corners region where rainfall since June 15 has been above average (see page 12).
In the past 30 days many regions in New Mexico and Arizona have received more than 130 percent of average precipitation, though large dry areas stretch across the Southwest (Figures 2c–d). The copious precipitation came during a wet week, when a low pressure system helped create favorable conditions for widespread and heavy monsoon precipitation. The recent rainfall in southeastern Arizona and southwestern New Mexico has brought some relief from exceptional short-term drought in both states. However, as has been the story in the last year, the southeastern third of New Mexico generally has been dry, receiving between 5 and 50 percent of average precipitation.Notes:
The water year begins on October 1 and ends on September 30 of the following year. As of October 1, 2010, we are in the 2011 water year. The water year is a more hydrologically sound measure of climate and hydrological activity than is the standard calendar year.
Average refers to the arithmetic mean of annual data from 1971–2000. Percent of average precipitation is calculated by taking the ratio of current to average precipitation and multiplying by 100.
The continuous color maps (Figures 2a, 2c) are derived by taking measurements at individual meteorological stations and mathematically interpolating (estimating) values between known data points. Interpolation procedures can cause aberrant values in data-sparse regions.
The dots in Figures 2b and 2d show data values for individual meteorological stations.
For these and other precipitation maps, visit:
For National Climatic Data Center monthly precipitation and drought reports for Arizona, New Mexico, and the Southwest region, visit :
Southwest Climate Outlook Staff
- Michael Crimmins, UA Extension Specialist
- Stephanie Doster, Institute of the Environment Editor
- Gregg Garfin, Founding Editor, Institute of the Environment
- Zack Guido, Managing Editor, CLIMAS Associate Staff Scientist
- Nancy J. Selover, Arizona State Climatologist
- Jessica Dollin, CLIMAS Publications Assistant
- Dave Dubois, New Mexico State Climatologist
Please direct your Southwest Climate Outlook comments and suggestions to Zack Guido.
The CLIMAS Web site 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.... Read full disclaimer