Each week the map’s author analyzes numerous types of information and products from all entities and levels of government dealing with drought and across multiple time scales. Most of this information falls into one of the following categories: precipitation, streamflow, reservoir levels, temperature and evaporative demand, soil moisture, vegetation health, drought impact reports captured from media outlets and submitted by private citizens, and expert local input from over 400 individuals. Authors now use several dozen indicators while creating the U.S. Drought Monitor. However, not all areas are represented equally by all sources of data.
Because the USDM depicts both short‐ & long‐term drought conditions, the authors must look at data for multiple time scales. The final map produced each week represents a convergence of evidence or a summary of the story being told by all of the pieces of data.