Wyoming Surface Water Supply Index (01 February 2022)
The Surface Water Supply Index (SWSI) is computed using only surface water supplies for the drainage. The computation includes reservoir storage, if applicable, plus the forecasted runoff. The index is purposely created to resemble the Palmer Drought Severity Index, with normal conditions centered near zero. Adequate and excessive supply has a positive number and deficit water supply have negative values. Soil moisture and forecast precipitation are not considered as such, but the forecasted runoff may consider these values. Note: Insufficient data exist to calculate SWSI values for the South Platte, Little Missouri, Niobrara and Great Divide Basins.
