The National Drought Mitigation Center Drought Atlas project is intended to provide a wide range of decision makers with historical drought information and a web-based tool to visualize and assess their risk to drought. A station-based approach lets you find the station closest to your area of interest as well as a cluster of stations that statistically has shown similar precipitation attributes. The stations with the longest period of record, a minimum of 40 years, with the most complete record, were used to compute both the climatological and drought information to provide users with information from the best station data available, through 2017.
Why a drought atlas? With every drought, people ask, “How does this drought compare … ?”, and the comparisons are usually to the most recent drought, the drought of record for an area, or a historical drought such as the Dust Bowl that is remembered even beyond the area that it affected. Until now, the answers haven’t been readily available for individual stations, and more often than not have only been available for climate divisions. The NDMC Drought Risk Atlas will answer all of these questions and provide user-friendly access to the data.
The drought atlas project also recognizes that not every drought index is ideal for every location. By providing several different indices with multiple time steps, the Drought Risk Atlas gives users a vast menu of options to study and investigate drought for their region.
An original Drought Atlas was done in conjunction with the United States Army Corps of Engineers by Hoskings, Wallis and Guttman in the early 1990s. The original Drought Atlas consisted of those stations in the Historical Climate Network (HCN), numbering approximately 1,000. The period of record was limited, as many stations only had records from the 1940s to present, and these data points were put into their respective climate divisions. A monthly time step was used to calculate the Palmer Drought Severity Index (PDSI). The new Drought Risk Atlas brings precise climatological data down to spatial scales that will allow decision makers to make practical use of this tool.
For the new national Drought Risk Atlas, the idea was to expand the data both in the number of stations analyzed and the period of record to include the most complete long-term stations, some of which are not part of the HCN. Using a weekly time-step to calculate multiple drought indices at each station location, not on a climate division scale, allows for a more precise representation of drought histories. The Standardized Precipitation Index (SPI), Standardized Precipitation-Evapotranspiration Index (SPEI), Palmer Drought Severity Index (PDSI), Deciles, United States Drought Monitor and other climatological data are included in the new Drought Risk Atlas. Along with the climatological data, gridded maps created on a weekly time-step are available for the entire United States. The NDMC’s Drought Risk Atlas first went online in 2014, and was updated in 2019 to include data through 2017.
This work is funded under a grant from the Sectoral Applications Research Program (SARP) of the NOAA-Climate Program Office. Additional Funding was provided by the NIDIS Program Office and the USDA-Risk Management Service (RMA).
Drought Risk Atlas Partners
If you would like to use any of the data from the Drought Risk Atlas, please cite the following sources:
- The National Drought Mitigation Center for any of the information contained in the Drought Risk Atlas
- The serially complete dataset was compiled by the High Plains Regional Climate Center and the National Drought Mitigation Center
- The raw dataset was obtained from the Applied Climate Information System.