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Published April 25, 2012
Precipitation(data through 4/18/12)
Data Source(s): High Plains Regional Climate Center
Precipitation since the water year began on October 1 has been well below average across the Southwest for a third consecutive month. Since the end of December, winter storms that brought precipitation to the region have been few and far between; several events that ferried moisture slightly missed the Southwest, either passing to the north or to the south of the region. Since October 1, only the west-central counties of New Mexico have been wetter than average, with rain and snow measuring more than 200 percent of average in places; the wettest conditions have been in Cibola County (Figure 2a–b). Outside of this wet spot, most of New Mexico has received 50–90 percent of average precipitation. There have been only a few wetter-than-average conditions in Arizona. Several parts of the state have received less than 50 percent of average. The Upper Colorado River Basin, from which most of the streamflow in the Colorado River originates, also has experienced below-average rain and snow since October 1.
One storm, that began beginning on April 14, moved through the region and dropped significant rainfall on northwestern Arizona and west-central New Mexico, pushing totals for the last 30 days above average in parts of these regions (Figures 2c–d). The rest of Arizona and New Mexico, however, have received less than 75 percent of average precipitation, with many areas measuring less than 5 percent of average.Notes:
The water year begins on October 1 and ends on September 30 of the following year. As of October 1, 2011, we are in the 2012 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
- Dan Ferguson, CLIMAS Program Director
- Gregg Garfin, Founding Editor, Institute of the Environment
- Zack Guido, CLIMAS Associate Staff Scientist
- Gigi Owen, CLIMAS Assistant Staff Scientist
- Nancy J. Selover, Arizona State Climatologist
- Jessica Swetish, CLIMAS Publications Assistant
Please direct your Southwest Climate Outlook comments and suggestions to Zack Guido.
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