North America Drought Analysis and Prediction Tools

The following sets of tools, developed in collaboration with the NOAA Earth System Research Laboratory (ESRL) and Climate Prediction Center (CPC), provide analyses of observed precipitation conditions over the United States and Mexico using the Standardized Precipitation Index (SPI) for various accumulation periods, and probabilistic forecasts of future SPI values based upon two forecast methodologies. The historical datasets used include the CPC's global Unified gridded precipitation dataset (monthly totals) and the National Climatic Data Center's (NCDC) U.S. Climate Divisions monthly precipitation dataset.

SPI Forecast Tools: SPI Multi-Model Ensemble Forecast Tool
U.S./Mexico SPI Multi-Model Ensemble Forecast Tool
	In this tool probabilistic forecasts of SPI in future months are based upon forecast precipitation from the IRI Multi-Model Ensemble where the hindcast correlation skill exceeds the correlation skill of the SPI Persistence method. For starting months, leads, and locations where the correlation skill is lower than that associated with the SPI Persistence method, the SPI Persistence forecast is used. The tool allows the user to display maps of the probability of SPI falling below a user-selected threshold or the forecast SPI in a future month for a user-selected marginal probability over the U.S. and Mexico.
U.S. Climate Divisions SPI Multi-Model Ensemble Forecast Tool
	In this tool probabilistic forecasts of SPI in future months are based upon forecast precipitation from the IRI Multi-Model Ensemble where the hindcast correlation skill exceeds the correlation skill of the SPI Persistence method. For starting months, leads, and locations where the correlation skill is lower than that associated with the SPI Persistence method, the SPI Persistence forecast is used. The tool allows the user to display maps of the probability of SPI falling below a user-selected threshold or the forecast SPI in a future month for a user-selected marginal probability for U.S. Climate Divisions

SPI Forecast Tools: SPI Persistence Forecast Tool
U.S./Mexico SPI Persistence Forecast Tool
	In this tool probabilistic forecasts of SPI in future months are based upon the correlation between SPI calculated for a future month (using recently-observed and historical observed mean precipitation) and the SPI calculated for the recently-observed months that overlap. The tool allows the user to display maps of the probability of SPI falling below a user-selected threshold or the forecast SPI in a future month for a user-selected marginal probability over the U.S. and Mexico.
U.S. Climate Divisions SPI Persistence Forecast Tool
	In this tool probabilistic forecasts of SPI in future months are based upon the correlation between SPI calculated for a future month (using recently-observed and historical observed mean precipitation) and the SPI calculated for the recently-observed months that overlap. The tool allows the user to display maps of the probability of SPI falling below a user-selected threshold or the forecast SPI in a future month for a user-selected marginal probability for U.S. Climate Divisions

Historical Analyses of SPI
U.S./Mexico SPI Analysis Tool
	This tool displays maps of historical SPI3, SPI6, SPI9, and SPI12 over the U.S. and Mexico and allows the user to point and click on a location to see historical time series of these indices.
U.S. Climate Divisions SPI Analysis Tool
	This tool displays maps of historical SPI3, SPI6, SPI9, and SPI12 U.S. Climate Divisions and allows the user to point and click on a location to see historical time series of these indices.

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