Mid-Mississippi Valley Flood Event Blasts Through The Record Books | WeatherBug
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Mid-Mississippi Valley Flood Event Blasts Through The Record Books

August 1, 2022
By WeatherBug Sr. Meteorologist, Chad Merrill
Summertime thunderstorms are notorious for producing very heavy rain in a short time that can trigger flash flooding. One Midwest city found this out while sleeping overnight and the result was a catastrophic and historical event that left many under water.

One of the main culprits for flash flooding in the summer are stationary fronts. These fronts move slowly, if at all, and often produce multiple rounds of showers and thunderstorms that repeatedly move over the same location. 

Late on July 25, 2022, a stationary front across southern Missouri tapped into a moist air mass over the Gulf of Mexico and produced repeated thunderstorms for more than six hours along the Interstates 64 and 70 corridors in Missouri and Illinois. Radar and observer reports confirm 11 inches fell in eight hours from Hawk Point, Mo., to St. Peters, Mo. 

St. Louis-Lambert International Airport shattered two records with this event. A total of 9.04 inches fell in a 24-hour period from July 25-26, besting the previous 24-hour rainfall record of 7.02 inches on August 19-20, 1915 from the remnant moisture associated with the Galveston 1915 hurricane. Of that 9.04 inches, 8.64 inches fell on July 26, establishing the new daily precipitation record for that day. To put the historical significance of this rainfall in perspective, 7.68 inches accumulated in six hours. Rainfall extremes like this only have a less than 1 in 1,000 chance of occurring in a given year! 

Unfortunately, the flash flooding claimed two lives, one in St. Louis where a man drowned in his car near Skinker Boulevard and another in Hazelwood, Mo., where a man drowned while attempting to flee his flooded truck. 

Southern Missouri has been a hot spot for flood fatalities in the last 20 years. Data from the National Oceanic and Atmospheric Administration indicates 24 flood deaths have occurred in the area around St. Louis into adjacent western Illinois from 2010 to 2021. The zone from the southern Plains to the Tennessee Valley, including St. Louis, has seen more flood-related deaths than any other part of the Central U.S. Besides tropical moisture, stationary fronts such as the one that blasted St. Louis with record rainfall on July 26, 2022, are the culprits for many flash flood events. 

The late-July event pushed St. Louis to its second wettest July on record with 12.22 inches. Not far behind was July 1948 when 12.69 inches accumulated in the rain gauge. The record wet July came on the heels of the eleventh driest June on record with only 1.79 inches. Historically, St. Louis sees 4.49 inches of rain in summer’s first month.

August will likely yield below-average rainfall in the Mid-Mississippi Valley. St. Louis averages 3.38 inches of rain for summer’s final month. 

The flooding events that unfolded in the St. Louis area at the end of July serve as a friendly reminder to “Turn Around, Don’t Drown,” when approaching a flooded roadway. Water is usually deeper than what it appears. Download WeatherBug on your mobile phone to keep ahead of the latest severe weather warnings and forecasts for your area. 
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Story Image: Flooding is seen at Forest Park DeBaliviere MetroLink station in St. Louis during the late July 2022 historical rainfall event. (Courtesy of the National Weather Service in St. Louis)