Draft:July 2024 Midwest derecho

A widespread derecho impacted the Midwestern United States, mostly the states of Iowa, Illinois, and Indiana, between July 15–16, 2024. Extreme atmospheric instability fueled the development of a powerful bowing mesoscale convective system that caused widespread wind gusts upwards of 75 mph, especially across Illinois, as well as multiple tornadoes that affected the cities of Des Moines and Davenport, Iowa, as well as the Chicago metropolitan area. One fatality has been confirmed from Indiana, with tornadoes killing another in New York.

Meteorological synopsis
The Storm Prediction Center outlined a moderate risk convective outlook at 20z, as extreme atmospheric instability and favorable vertical wind shear was predicted to be favorable to the formation of a bowing mesoscale convective system. Initial estimates stated that widespread wind gusts up to 60-75 mph would be likely, as well as occasional gusts up to 85 mph.

Concerns over the predictability of the incoming system prompted a rare 19z sounding from National Weather Service Quad Cities, Iowa/Illinois, near Davenport, Iowa. The returning sounding indicated extreme atmospheric instability values over 6500 J/kg, as well as a favorable vertical shear profile, indicating atmospheric favorability for a strong quasi-linear convective system, potentially with embedded tornadoes.

Derecho
The derecho left 350,000 customers without power from Iowa to Michigan. Wind gusts reached 105 mph in Camp Grove, Illinois. At Chicago O'Hare International Airport, gusts reached 75 mph. The derecho also closed portions of Interstate 55 in Illinois. In Indiana, a woman was killed by a tree falling onto their house in Cedar Lake, with gusts up to 71 mph in Athens. Further east, 102,000 customers lost power in the Northeastern United States.