Data through September 17, 2013. Data Source: U.S. Drought Monitor
Several bouts of widespread monsoon activity associated with incursions of tropical moisture led to substantial improvements in short-term drought conditions in much of Arizona during the past 30 days. The U.S. Drought Monitor now classifies some parts of Arizona as drought free (Figures 4a–b). The largest improvements in northern and western parts of the state received most of the precipitation over the month, experienced. Many areas classified with either severe or extreme drought in mid-August have now improved to the moderate drought or abnormally dry categories. Overall, precipitation amounts were between 150 and 200 percent of average across these areas. However, the monsoon did not soak all of the state. Parts of central Arizona, including the Tucson metro area, fell behind in precipitation and have remained stuck at the severe drought level.
The Arizona section of the U.S. Drought Monitor is released weekly (every Thursday) and represents data collected through the previous Tuesday. The 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.