The West Wide Drought Tracker: drought monitoring at fine spatial scales

Drought monitoring in the western United States (US) is particularly challenging due to complex terrain that creates sharp gradients in precipitation and atmospheric demand and corresponding fine-scale hydroclimatic variability. Coarse scale climate data and drought indices are valuable for large scale regional assessments, but often provide insufficient detail for local application of drought information and decision-making in the West. The current ongoing severe drought in California and increased water scarcity across much of the southwestern US over the past couple decades have prompted demand for accessible drought decision-making information at fine spatial scales. The West Wide Drought Tracker (WWDT) is a web application that responds to the needs of drought monitoring across the western US by providing a suite of current and historical monthly drought indices including the Palmer Drought Severity Index, Standardized Precipitation Index, and Standardized Precipitation Evapotranspiration Index at fine spatial scales (~4-km) across the contiguous US. A web-interface facilitates users to access a variety of maps and time-series for monitoring the multi-scalar nature of drought and to compare conditions to records dating back to 1895. The availability of drought monitoring products and functionality of the WWDT provide a valuable resource for decision-makers and researchers that incorporate drought impacts and risks.