Drought Termination and Amelioration
Changes will be made to this page in the months ahead to streamline and improve its functionality ().
NCEI's Drought Termination and Amelioration web page presents information useful for determining the reduction or ending of drought, based on the Palmer Drought Index model. The type of drought reduction is expressed as six variables: the amount of precipitation needed to end a drought, the percent of normal corresponding to this precipitation amount, and the historical probability of receiving this precipitation; and the amount of precipitation needed to ameliorate (reduce the intensity of) drought, the percent of normal corresponding to this precipitation amount, and the historical probability of receiving this precipitation. Each of these variables is computed for each of six durations, ranging from 1 month to 6 months, for the 344 climate divisions in the contiguous United States. The information is provided in graphical map form as well as an ASCII plain text file.
The following changes have been implemented: 1) in addition to an ASCII plain text file, the information is provided in xml, csv, and json formats; and 2) a toggle switch has been added that enables the user to compare the map of drought termination or amelioration statistics to be compared to a map showing the current PHDI drought status.
The following changes will soon be implemented: 1) six additional durations will be added, for a total of twelve durations (from 1 to 12 months); 2) the file record format of the txt, xml, csv, and json files will be changed to allow easier identification of the climate divisions and to accommodate the additional durations.
Additional changes planned for the future: 3) produce regional maps in addition to national maps; 4) do the analysis using gridded data in addition to climate division data.
Climatological Drought Reduction
To view maps of precipitation required to end or ameliorate drought across the Contiguous U.S., and the probability of receiving that precipitation, select from the options below and then click "Submit".
The end of a drought is defined by a PHDI value of -0.5.
Drought amelioration is achieved when a PHDI value of -2.0 is reached.