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Published February 27, 2013
U.S. Drought Monitor(data through 2/19/13)
Data Source(s): U.S. Department of Agriculture, National Drought Mitigation Center, National Oceanic and Atmospheric Administration
Winter storms have consistently wafted through the Pacific Northwest and northern Rockies this winter, helping these regions remain drought-free. The rest of the West has not fared as well; short and long-term drought conditions exist in most regions (Figure 3). The distinction between short- and long-term drought depends on how sensitive an environment or sector is to change. For example, it takes many months of below-average precipitation to dwindle the water supply in a large reservoir, whereas much shorter dry periods can cause grasses to wilt.
During the past 30 days, the extent and intensity of drought has remained relatively constant. A wet winter storm in late January brought some short-term relief to parts of Arizona, helping improve drought conditions in the central part of the state, but that storm did little to help other areas in the Southwest. Drought conditions intensified across Colorado and New Mexico where the area covered by extreme and exceptional drought expanded. Abnormally dry conditions along the coast of northern California also recently materialized. Overall, moderate drought covers 64 percent of the western U.S., a slight improvement from 68 percent in mid-January. The level of exceptional drought in the West, however, increased from 2.2 percent in mid-January to 3.5 percent in mid-February.
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 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