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On This Day in 2006: St. Louis Derecho
July 18, 2021 at 02:17 PM EDT
By WeatherBug's Intern Meteorologist, Christopher Smith
July marks the peak of summer and the prime time of a type of severe weather called a derecho. On this day 15 years ago, a derecho tore through a large metropolitan area in the Mid-Mississippi Valley, impacting millions.
A derecho is formally defined as a complex of storms that delivers severe wind gusts of at least 58 mph, perhaps reaching up to 75 mph, and ripping a path of more than 250 miles. The set-up for the 2006 derecho across the Middle Mississippi Valley featured a very hot, humid air mass. High temperatures on July 19, 2006, reached 100 degrees in St. Louis and when factoring in the humidity, the heat index peaked at 110 degrees.
The origin of the derecho was in northern Illinois when a series of storms formed during the afternoon. As the storms tapped into the sultry airmass, they gained strength and produced widespread damaging wind gusts. In addition, two tornadoes were also reported as the storms swept southwest through Illinois into Missouri.
Wind gusts from 70 to 90 mph ravaged western Illinois and eastern Missouri, including the St. Louis metro. A whopping 500,000 customers were left without power and no air conditioning amid a grueling heat wave.
Unfortunately, the weather wasn’t pleasant in the days following for those in St. Louis. Temperatures the following day once again reached the upper 90s, making the clean-up harsh. Another round of severe weather also struck on July 21, 2006, once again knocking out power to more than 500,000 customers and causing widespread damage.
Source: weather.gov
A derecho is formally defined as a complex of storms that delivers severe wind gusts of at least 58 mph, perhaps reaching up to 75 mph, and ripping a path of more than 250 miles. The set-up for the 2006 derecho across the Middle Mississippi Valley featured a very hot, humid air mass. High temperatures on July 19, 2006, reached 100 degrees in St. Louis and when factoring in the humidity, the heat index peaked at 110 degrees.
The origin of the derecho was in northern Illinois when a series of storms formed during the afternoon. As the storms tapped into the sultry airmass, they gained strength and produced widespread damaging wind gusts. In addition, two tornadoes were also reported as the storms swept southwest through Illinois into Missouri.
Wind gusts from 70 to 90 mph ravaged western Illinois and eastern Missouri, including the St. Louis metro. A whopping 500,000 customers were left without power and no air conditioning amid a grueling heat wave.
Unfortunately, the weather wasn’t pleasant in the days following for those in St. Louis. Temperatures the following day once again reached the upper 90s, making the clean-up harsh. Another round of severe weather also struck on July 21, 2006, once again knocking out power to more than 500,000 customers and causing widespread damage.
Source: weather.gov