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Published September 20, 2011
U.S. Drought Monitor(data through 9/13/11)
Data Source(s): Data Sources: U.S. Department of Agriculture, National Drought Mitigation Center, National Oceanic and Atmospheric Administration
Drought conditions in the U.S. remain largely confined to southern states and the Southwest (Figure 3). This national pattern reflects the dry conditions brought on by La Niña last winter.
In the last month, abnormally dry conditions expanded into southern Nevada and eastern Colorado due to a couple of hot and dry spells. Meanwhile, monsoon precipitation, albeit spotty, helped provide some short-term relief in parts of New Mexico and southern Colorado. The rest of the western U.S. remains drought-free, as it has since last January when record precipitation started to fall across areas from California to Montana. The NOAA-Climate Prediction Center has issued a La Niña Advisory, which means that La Niña conditions have developed and are expected to persist for the at least the next six months (see page 16).
NOAA will issue its official winter outlook in mid-October, but La Niña winters often mean drier-than-average conditions across the southern tier of the U.S. and wetter-than-normal conditions in the Pacific Northwest and Ohio Valley.
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 Mark Svoboda, Natoinal Drought Mitigatoin Center.
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
- 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.
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