Enhancements made to the Drought Risk Atlas from the National Drought Mitigation Center

The National Drought Mitigation Center (NDMC) created the Drought Risk Atlas (DRA) in 2013 and made climate and drought histories available for 3,059 stations.  Stations included in this project were selected from the National Weather Service’s Cooperative Observer Program (COOP) network of stations through strict criteria: a period of record of at least forty years and no more than two consecutive months missing.  Recently, it became clear that stations that did not fit the initial criteria could also be of value, especially in the western United States and other areas with fewer stations.  All the stations in the COOP network were re-examined  again, this time with a plan to create a laxer set of guidelines for station selection. Ultimately, to be included in the DRA, stations were required to have: a period of record of at least forty years, data gaps of two consecutive years or less, and five gaps or less in the last forty years of its record.  In this search, 2,945 stations were evaluated, 223 were found to meet the original criteria (period of record of 40 plus years and no greater than two months missing), and 910 that met the new standards.  In total, 1,133 will be added to the NDMC’s Drought Risk Atlas where drought indices such as the Standardized Precipitation Index, the Standardized Precipitation Evapotranspiration Index, the Palmer Drought Severity Index, the self-calibrated Palmer Drought Severity Index, and deciles will be run and available to the public at http://droughtatlas.unl.edu/. With this data set there is a guaranteed long period of record with minimal gaps, which gives a stronger, more reliable climate signal and a better opportunity to see extremes. The update to the DRA is especially important to areas in the western United States where there were previously few stations included; by lowering the criteria for station acceptance, the proximity of stations to people will greatly improve increasing the utility of the DRA as a decision making tool.