The Palmer Drought Index (PDI) and Palmer Hydrological Drought Index (PHDI) shown on this web page represent a way of estimating the monthly PDI and PHDI on an operational weekly basis. If the date of the maps is before the end of the month, then observed temperature and precipitation through the date of the map are combined with 1971-2000 normals of temperature and precipitation for the remainder of the month to create an estimate of the monthly temperature and precipitation values. These estimated monthly temperature and precipitation values are fed into the Palmer model to compute the monthly PDI and PHDI values for the date in question.
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Weekly Palmer Drought Indices
How to use this site:
- Use the drop-down options to select a “Year” “Month” and “Day”
- Select “Submit” and maps will update
- Download data, available in XML/CSV/JSON, by selecting the data format beneath the maps
- Select image to enlarge it
Documentation for Weekly Palmer Drought Indices:
- Heim, R.R., Jr., 2002: A review of Twentieth-Century drought indices used in the United States. Bull. Amer. Meteor. Soc., 83, 1149-1165.
- Heim, R.R., Jr., 2005: Computing the monthly Palmer Drought Index on a weekly basis: A case study comparing data estimation techniques. Geophys. Res. Lett., 32, No. 6, L06401, 18 March 2005.
- Palmer, W.C., 1965: Meteorological drought. Research Paper No. 45. U.S. Weather Bureau. [NOAA Library and Information Services Division, Washington, D.C. 20852]
Data Source: National Centers for Environmental Information
Data Type: Land-based Station
Period of Record: 12-Apr-2005 to Present
Data Format: csv images json xml