The Top Ten Disasters of 2020 - #4 The August Derecho

derecho

Tidal Basin reviews the biggest disasters of the year

Tidal Basin has identified the Top Ten Disasters of 2020 based on significant events throughout the year that caused historical impacts including a major severe weather event in early August. A cluster of severe storms, called a Derecho, caused extensive damage in several Midwestern states including Iowa. Derechos are classified as a widespread wind event with have a continuous damage path of greater than 250 miles with a continuous area of winds of 58 mph, with some embedded stronger winds greater than 70 mph. The August Derecho created a 750-mile path of damage with peak winds over 100 mph, with some gusts as high as 140 mph in Central Iowa.

No. 4 — The August Derecho

The state of Iowa experiences a derecho about once every other year according to the National Weather Service’s Michael Fowle. “This will be one of those in the top 5 in the history of derechos in Iowa,” who is the Science and Operations Officer for the Des Moines office. “About 48 hours before the storm struck there was some indication of potential severe weather in the state. But the forecast models did not pick up on the extreme intensity of the system until the night before the storms developed,” said Fowle.

The derecho grew out of a complex of storms that moved rapidly across several states leaving behind catastrophic damage. The system produced a cluster of severe thunderstorms and isolated tornadoes that severely impacted central Iowa with wind gusts equivalent to a category 3 hurricane with winds peaking over 120 miles per hour (see diagram).

The impacts to Iowa were widespread and long lasting with power outages lasting over a week in some locations. The state received a Presidential Disaster Declaration the week following the storms for sixteen of the hardest hit counties. 

In August we spoke with Iowa’s Division Director of Homeland Security and Emergency Management, Joyce Flinn who said this disaster was one of the worst the state has experienced in many decades. “This is the most power outage we’ve had in a large part of the state that has gone on as long as it has - significant [agricultural] damage the likes that we’ve never seen before,” said Flinn. The damage to the state’s power grid system delayed restoration efforts for some of the hardest hit communities in the state. “Power poles were snapped and tangled. We had crews in from Canada and other states. At point we had over 1,700 crews working in the state to support the power restoration effort,” she said.  

In Episode 8 of our Disaster Recovery Roundtable Podcast series, Director Flinn recommended the emergency management community rethink how they exercise and prepare for mass power outage events. “We don’t place enough emphasis in our preparedness training in long term power outages.  We have typically looked at preparing for three days, and in this case, we needed 2 1/2 times that much preparation,” she said. She recommended updating outreach to the public to prepare for longer term power outages to ensure they have the resources needed for a major event like the recent derecho.

Overall, the August Derecho event impacted five midwestern states including Iowa, Illinois, Indiana, Wisconsin, and Michigan. The system produced 25 tornadoes, caused an estimated two million to lose power, and resulted in and estimated 7.5 billion dollars in damages, including three billion to Iowa’s corn and soybean crops.

Stay tuned for #3 on our list of the Top Ten Disasters of 2020.

To view what made our Top Ten list so far, click below: