A flash drought is an extreme dry spell. Of late, it is becoming a big concern for farmers and water utilities in some countires, 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.
Flash droughts also can increase wildfire risks, cause public water supply shortages and reduce stream flow, which harms fish and other aquatic life.
What causes them?
Flash droughts typically result from a combination of lower-than-normal precipitation and higher temperatures. Together, these factors reduce overall land surface moisture. Reduced moisture at the surface increases surface air temperatures, drying out the soil. Even moist regions can have flash droughts. In 2017, a flash drought in Montana and the Dakotas damaged crops and grasses that served as forage for cattle, causing U.S. $2.6 billion in agricultural losses.
Difficult to predict
Predicting flash drought events that occur on monthly to weekly time scales is much harder with current data and tools, largely due to the chaotic nature of weather and limitations in weather models. That’s why weather forecasters don’t typically make projections beyond 10 days there is a lot of variation in what can happen over longer time spans. And climate patterns can shift from year to year, adding to the challenge.
Early warnings
New monitoring tools that measure evaporative demand can, however, provide early warnings for regions experiencing abnormal conditions. Information from these systems can give farmers and utilities sufficient lead time to adjust their operations and minimise their risks.
The U.S. story
Flash droughts started receiving more attention in the U.S. after notable events in 2012, 2016 and 2017 that reduced crop yields and increased wildfire risks. In 2012, areas in the Midwest fell into severe drought conditions in June and July, causing more than $30 billion in damages. New England, typically one of the wetter U.S. regions too experienced a flash drought in the summer of 2022.
Picture Credit : Google
