Flash droughts early warning based on evaporative stress forecasts

Abstract

<p>Flash droughts are regional phenomena that can manifest in region areas with a rapid intensification, and that often last for short periods of time. Flash droughts have received considerable scientific attention in recent years. However, their prediction is still a challenge, largely due to their abrupt onset and often unknown regional drivers. Here, we establish a forecast system to predict flash droughts at a medium-range weather scale. The system uses forcing data from the Multi-Source Weather (MSWX), an operational, high-resolution (3‑hourly, 0.1°), bias-corrected meteorological product with global coverage from 1979 to several months into the future (Beck et al. 2021). MSWX data are used as input to the Global Land Evaporation Amsterdam Model (GLEAM), more specifically its recent hybrid version (Koppa et al., 2021). This allows us to compute forecasts of actual and potential evaporation;  the ratio of both (also know as 'evaporative stress') is used here as flash drought diagnostic. This forecast system is evaluated on its ability to predict flash droughts globally and 2, 4, 7 and 10 days advance. The new tool shows potential to improve our understanding of flash droughts, and it serves as an early prediction system to enable more efficient agricultural and water management.</p><p> </p><p>