Data Source(s): U.S. Department of Agriculture; National Drought Mitigation Center; National Oceanic and Atmospheric Administration
Drought across the West remained largely unchanged since mid-June. The most extreme conditions continue to be in New Mexico, where about 90 percent of the state is classified with extreme or exceptional drought (see New Mexico Drought Status).
In the last 30 days, a large ridge of high pressure dominated the weather pattern across the western U.S. While this helped deliver some monsoon moisture to Arizona and New Mexico, it left most other states dry. Areas where drought conditions worsened included parts of northern Nevada, southern Idaho, and Wyoming, where less than 50 percent of average precipitation fell in the last month. Overall, 85 percent of the western U.S. is experiencing at least moderate drought, with 59 percent categorized as severe or worse (Figure 3). One month ago, 51 percent of the West was classified with severe drought or worse. In coming months, the expectation is that drought will improve in the Southwest, but largely persist or intensify elsewhere in the West (see Seasonal Drought Outlook).
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.