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Published September 23, 2010
U.S. Drought Monitor(data through 9/14/10)
Data Source(s): U.S. Department of Agriculture, National Drought Mitigation Center, National Oceanic and Atmospheric Administration
The extent of drought conditions across the western U.S. has not changed much in the past 30 days, according to the September 14 update of the U.S. Drought Monitor (Figure 3). Monsoon rains generally have been near average for the region, although there has been large spatial variability that has left some areas drier than others—a common occurrence during the monsoon. Northern and western Arizona are currently experiencing the brunt of the drought conditions in the region.
In other areas, dry conditions have plagued western Nevada and parts of northern California for most of the summer. Although these areas typically don’t experience much summer precipitation, less than 0.5 inches have fallen in many parts of this large region in the past 90 days. In the central Rockies, a dry spell has promoted the expansion of abnormally dry conditions over northern Colorado. Overall, approximately 27 percent of the West is classified with abnormally dry conditions or worse, just a 2 percent increase from one month ago.
The U.S. Drought Monitor is released weekly (every Thursday) and represents data collected through the previous Tuesday. The inset (lower left) shows the western United States from the previous month’s map.
The U.S. Drought Monitor maps are based on expert assessment of variables including (but not limited to) the Palmer Drought Severity Index, soil moisture, streamflow, precipitation, and measures of vegetation stress, as well as reports of drought impacts. It is a joint effort of several agencies; the author of this monitor is Matthew Rosencrans, NOAA/NWS/NCEP/CPC.
The best way to monitor drought trends is to pay a weekly visit to the U.S. Drought Monitor website:
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