The recent series of severe convective storm systems that hit the southern and eastern United States from May 16-22 are expected to cause economic and insured losses amounting to billions of USD, according to Aon’s weekly catastrophe report.
Aon reported that on May 16-17, a derecho system formed over central Texas and moved eastward along the Gulf Coast towards central Florida. The National Weather Service (NWS) noted that winds reached 100 mph, accompanied by at least three EF1 tornadoes.
The derecho caused widespread damage, leaving over 1 million people without power at its peak. In Houston, strong winds and hail damaged many commercial and residential buildings, shattering approximately 2,500 skyscraper windows.
Aon noted that on May 19, severe thunderstorms hit Kansas, Oklahoma, and Missouri. In Kansas, a state of emergency was declared in several areas, with Harvey, Osage, and Newton counties being the hardest hit.
Further storms were recorded on May 20 between Michigan and Colorado, particularly affecting Yuma and Wray, which experienced extensive hail damage and flooding of homes, properties, and cars.
The following day, Iowa, Wisconsin, Illinois, Nebraska, and Missouri were impacted. Iowa, in particular, faced a violent EF4 tornado with winds estimated by the NWS at up to 185 mph (300 kph), devastating the city of Greenfield and destroying at least 100 buildings. Omaha, Nebraska also reported significant flooding damage.
The storm series concluded with a major tornado in Temple, Texas on May 22, which caused buildings to be lifted off their foundations and roofs to be torn off.
Aon stated that the damage was caused by a combination of strong winds, tornadoes, large hail, and heavy rain, with the derecho likely being the most costly single event.
The firm added, “As damage assessments and claim filing will continue, it is too early to provide a definitive estimate of eventual financial impacts. However, given the extent of damage and the exposure centres hit by the event, it is very likely that the event will result in losses in the billions of USD.”
