Furious Derecho flattens Iowa corn and soybeans with hurricane-force winds

Despite a dry July, many farmers in Iowa expected a good harvest in the fall. Instead, many saw their corn and soybean fields flattened by hurricane-force winds.

On August 10, 2020, an unusually strong and lasting line of thunderstorms – a derecho – hit large swathes of Iowa and the U.S. Midwest. More than a week after the storm, tens of thousands of Iowans were still without power and many farmers wondered if they could salvage crops and repair grain elevators before the upcoming harvest.

The Operational Land Imager (OLI) on Landsat 8 captured an image of storm-damaged fields around Marshalltown, Iowa, the day after the storm. For comparison, the second image shows the same area on July 10, 2020. Wind damaged crops appear in light green. Darker areas in the damaged swath can be broken trees or fields where crops have suffered less damage.

While large hail can quickly pull out stems and spray corn and soybean plants – leaving dark brown streaks across rural landscapes – much of the damage in August 2020 was caused by high winds that knocked over stalks already heavy with ripening corn husks, explained Christopher Schultz, a NASA Meteorologist at the Marshall Space Flight Center. However, the damage was not exclusively caused by the wind. In some areas, small plants hail and cut the leaves.

It is possible that some of the spilled plants still have roots intact and will continue to grow in the weeks to come; others could be used for silage or other purposes. But many experts predict serious losses and great challenges in harvesting and storing whatever is left. As damage estimates evolve, agricultural economists predict the storm likely caused nearly $ 4 billion in damage, which would make it one of NOAA’s costliest thunderstorms on weather and climate disaster tracking. of the last decade.

“This is by no means the first time the Midwest has seen severe thunderstorms damaging crops, but the vast extent of the damage here really stands out,” said Jordan Bell, another NASA Marshall researcher who has followed the ‘event. “We are talking about an order of magnitude larger damage band than other tornadoes or thunderstorms that we have seen in the past. It is an event that people will remember for a long time. A larger view of the damage caused by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor is available here.

Schultz and Bell are part of a NASA Applied Earth Science project that aims to develop climatologies of hailstorms in North America and around the world. Such data could help insurance companies and other stakeholders assess the risk of crop losses due to severe thunderstorms.

“We use a whole suite of sensors to detect storms and assess the damage they cause,” said Kristopher Bedka, project leader. “And we are doing it not only for this event, but also for catastrophic events all over the world so that we can learn to better quantify the damage in an automated way.”

Images from NASA’s Earth Observatory by Joshua Stevens, using Landsat data from the US Geological Survey.