Monday June 26, 2023
SF Gate —
Many people are familiar with flash floods – torrents that develop quickly after heavy rainfall. But there’s also such a thing as a flash drought, and these sudden, extreme dry spells are becoming a big concern for farmers and water utilities.
Flash droughts start and intensify quickly, over periods of weeks to months, compared to years or decades for conventional droughts. Still, they can cause substantial economic damage, since communities have less time to prepare for the impacts of a rapidly evolving drought. In 2017, a flash drought in Montana and the Dakotas damaged crops and grasses that served as forage for cattle, causing US$2.6 billion in agricultural losses.
Flash droughts also can increase wildfire risks, cause public water supply shortages and reduce stream flow, which harms fish and other aquatic life.
Less rain, warmer air
Flash droughts typically result from a combination of lower-then-normal precipitation and higher temperatures. Together, these factors reduce overall land surface moisture.