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U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Invasive Species Risk Assessment

Moisture Surplus and Deficit Maps

The Moisture Surplus and Deficit maps represent the departure from typical moisture conditions over a 1-, 3-, and 5-year time period (Koch 2011). PRISM climate grids (4km resolution) were used to calculate a moisture index value for each location across the contiguous U.S. (CONUS), with the final product resampled to 1km resolution. Moisture index values incorporate both precipitation and potential evapotranspiration, giving an accounting of a location's water balance. Typical (i.e., long-term) moisture conditions are represented by the 100 year average and standard deviation. Moisture conditions over a 1-, 3-, or 5-year window are compared to the corresponding 100 year conditions to classify an area as having moisture deficit, surplus, or near normal conditions during the time period of interest.

Moisture Surplus and Deficit Maps Downloads (Conterminous US)

One Year Average (1.6 MB PDF)

Three Year Average (1.8 MB PDF)

Five Year Average (2 MB PDF)