Mother Nature kicked of the 4th of July celebrations early this year, with an impressive light show over the Chicago skyline earlier this week in which lightning struck three buildings (the Willis,Trump, and Hancock Towers) simultaneously (see attached picture). This display resulted from a specific type of organized thunderstorms called a derecho, which was only part of a larger system of storms that impacted a large part of the Midwest. The most affected states that suffered damages from this system included Iowa, Illinois,Wisconsin, and Indiana.
Most of the damages resulted from weak (EF0 and EF1)tornadoes and other wind gusts that exceeded 60mph leading to many downed trees and power lines. In Chicago, thousands were left without power and hundreds of flights were canceled from nearby airports. In Wisconsin, minor damage was reported with the exception of a camper-trailer that was thrown approximately100 yards by a tornado. Thankfully,there were relatively few injuries reported throughout the Midwest from the storm with the exception of Indiana where there were sadly two fatalities reported when some downed trees landed on houses.
Fortunately, this event spared many of the larger cities in the Midwest, including Chicago, from major damages. However, this event should be considered as a reminder that large metropolitan areas are at risk from these potentially devastating storms. In this case, the strongest part of the derecho happened to miss the Chicago area this time,sparing the city from greater damage. Furthermore, the tornadoes produced by this system were relatively weak rating as EF0s or EF1s on the Enhanced Fujita scale. It is not uncommon for severe storms in the Midwest to result in much stronger EF3, EF4, and EF5 tornadoes, which could lead to devastating damage, even in large cities like Chicago.
Swiss Re has an extensive expertise regarding the understanding of severe convective storms and the risks they pose to regions like the Midwest, Deep South, and Great Plains in the US. The complexity of these systems presents a number of challenges when it comes to modeling the risks associated with them. Therefore, in a recent publication, we use a simple and logic-based methodology to demonstrate the types of potential losses we might see if an EF5 tornado were to go through the heart of a major metropolitan area. The loss potential from such a scenario would be tremendous with possible losses reaching tens of billions of dollars. It is therefore imperative that we always keep vigilant in preparing for such a worst case scenario.
Category: Climate/natural disasters: Disaster risk, Floods/storms
Location: Chicago, IL, United States