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Published November 21, 2012
U.S. Drought Monitor(data through 11/13/12)
Data Source(s): U.S. Department of Agriculture, National Drought Mitigation Center, National Oceanic and Atmospheric Administration
A majority of the western U.S. continues to experience short- and long-term drought conditions, while the Pacific Northwest and parts of the northern Rockies remain free of drought (Figure 3). Short-term drought conditions usually refer to conditions that respond quickly to changes in drought, such as range conditions or forest moisture levels. Long-term drought usually reflects conditions with a longer response time, such as reservoir and groundwater storage. While above-average monsoon or winter precipitation will have marked improvements on short-term drought, long-term drought often needs successive seasons with average to above-average conditions.
In the past 30 days, several early winter storms took a northern track across the West, helping to keep drought conditions at bay in Washington, northern Oregon, and Idaho. These storms also helped improve short-term drought conditions that had developed over northern Montana over the past several months. Despite this, some level of drought covers more than 80 percent of the western U.S., with more than 40 percent classified as severeor more intense. These numbers are largely unchanged since last month, because most of the western U.S. has experienced below-average precipitation over the past 30 days.
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
- 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