![]() The warm front demarcating the northward push of the unstable air also focused the development of storms across the region. These convectively unstable conditions permeated across Iowa and were characterized by steep lapse rates in the mid-levels of the troposphere as sampled via weather balloon launches from Omaha, Nebraska, on the morning of August 10, and from Davenport, Iowa, at noon that day the atmospheric sounding retrieved from the Davenport balloon launch observed lapse rates of 8.5☌/km. The latter factor resulted from the conducive overlapping of moist air drawn northward across the Mississippi Valley and warm and dry air aloft originating from the Southwestern U.S., resulting in an elevated mixed layer that allowed instability to escalate. A combination of strong ambient winds and extreme convective instability facilitated the strength and unusual characteristics of the derecho. On average, the storm front traveled west-to-east at an average speed of 55 mph (88.5 km/h 24.6 m/s). Media outlets described the storm as an "inland hurricane". However, the August 2020 derecho was unusual for the longevity of the damaging winds it produced some areas were subjected to these winds for up to an hour compared to the 10–20 minutes of sustained damaging winds in a typical derecho, resulting in conditions similar to the passage of a hurricane's eyewall. As with derechos in general, the continuous downwelling of high winds associated with the nearby jet stream and the expansion of dense rain-cooled air in the storm's wake induced the destructive winds and the storm's motion. roughly once per decade, with similar derechos having occurred in 19. Weather radar imagery of the storm moving across the Midwestĭerechos of similar intensity to the August 2020 storm impact the Midwestern U.S. The derecho caused over $11 billion (2020 USD) in damages and spawned a years-long cleanup effort. Cedar Rapids, Iowa, was the most severely damaged, suffering a near-complete blackout that lasted for weeks in some areas, widespread and severe property damage, and an estimated loss of at least half of the city's tree canopy. Millions across the Midwest were affected by wide-scale utility disruptions, residential and commercial property damage, and severe damage to corn and soybean crops. The highest winds occurred in Iowa, measured at 126 mph (203 km/h 56.3 m/s) and highest estimated from post-event damage surveys at 140 mph (225 km/h 62.6 m/s). The greatest damage occurred in eastern Iowa, and northern Illinois, where multiple tornadoes touched down. ĭamage was moderate to severe across much of the affected area, as sustained wind speeds of 70 miles per hour (110 kilometers per hour 31 meters per second) were prevalent. Some areas reported torrential rain and large hail. It caused high winds and spawned an outbreak of weak tornadoes. The August 2020 Midwest derecho was a powerful derecho affecting the Midwestern United States on August 10–11, 2020, primarily eastern Nebraska, Iowa, Illinois, Wisconsin, and Indiana. 1 Most severe tornado damage see Enhanced Fujita scale
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