Figure 3. U.S. Drought Monitor (released 10/15/09)
Sources: U.S. Department of Agriculture, National Drought Mitigation Center, National Oceanic and Atmospheric Administration

Moderate to severe drought conditions persisted again this month in many parts of the West, with severe drought expanding dramatically across Arizona due to impacts from an exceptionally dry summer monsoon season (Figure 3). The area of western states impacted by drought conditions has risen steadily over the past several months, from near 45 percent in mid-July to more than 58 percent in mid-October. Abnormally dry conditions or worse blanket Washington, Oregon, and California and include much of Nevada and all of Arizona. The interior West, including Utah, Wyoming, Idaho, Montana, and Colorado, is largely devoid of drought conditions, as above-average spring and summer precipitation helped keep short-term drought conditions at bay.

In drought-related news, a coastal storm that pummeled the San Francisco Bay area with more than 10 inches of rain in some places helped bring some drought relief to California but didn’t erase current drought conditions (San Francisco Chronicle, October 15). A California Department of Water Resources meteorologist said the recent storm did not do much for the state’s water supply, which currently stands at 72 percent of average capacity.

Notes: 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 the several agencies; the author of this monitor is Rich Tinker, CPC/NCEP/NWS/NOAA.

More Information:
For the most recent drought monitor, visit: http://www.drought.unl.edu/dm/monitor.html.