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Keetch-Byram Drought Index Seasonal Initialization PDF

The Climate Prediction Center of the National Weather Service maintains estimates for a number of parameters associated with the Palmer Drought Index. These data can be used to determine a starting value for KBDI.

These data are available at:

We have developed an automated system to provide recommended KBDI initialization values for each of the four regions defined by the CPC.
Click the region below for the summary:

Central Climate Region

Eastern Climate Region

Western Climate Region

Southern Climate Region

KBDI starting values are assumed to be linearly related to percentage changes soil moisture expressed as a proportion of field capacity. The following equation is used to estimate KBDI:
KBDI = 8 * (100 - FC).

Click the CPC link above for a complete description of the climate divisions