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The Standard Precipitation Index Explorer Tool is a helpful tool for understanding severity of drought. The Standardized Precipitation Index (SPI) is a widely used drought index that has several strenghts including the ability to calculate precipitation anomalies at different timescales and the ability to interpret SPI units (standard deviations) in probabilistic terms. This tool was created to explore SPI values at specific locations by using a gridded climate dataset (PRISM Climate) to estimate local precipitation time series. Data are accessed through the Applied Climate Information Web Service and analyzed and plotted using several R based packages. This version of the tool includes the calculation of the Standardized Precipitation-Evapotranspiration Index (SPEI). See a CCAST Case Study that used the SPI Explorer Tool here: https://arcg.is/1zaaz81 and webinar here: https://youtu.be/nIGerxDY4ms?t=974