Some areas on the northwest side of St. Louis received more than 10 inches of rain in six hours overnight – an event with a 0.1% chance to occur in a given year. The heaviest rain had moved northeast by 8 a.m., but downpours continued to affect the city.
Rescuers were responding to numerous reports from drivers whose cars had been submerged in flooding. On a block in the western part of town, the St. Louis Fire Department said it used an inflatable boat to save six people and six dogs trapped in about 18 homes amid severe flooding. Fifteen people chose to shelter in place.
No injuries from the flooding had been reported by 10 a.m. local time, said Ann Vastmans, spokeswoman for the St. Louis County Office of Emergency Management.
Videos shared on social media showed many roads completely inaccessible. Part of a major highway, Interstate 70, was closed due to flooding, the Missouri Department of Transportation said.
St. Louis County emergency officials urged residents not to travel and said they had set up shelter for the displaced. The central part of the county was the hardest hit by the downpour, they said.
“Use extreme caution,” St. Louis firefighter Garon Patrick Mosby said in a video shared on Twitter. “We are overrun here.”
Extreme precipitation events have increased significantly over the past century and are linked to warming due to human-induced climate change. The most severe events of this type have increased by 42% in the Midwest between 1901 and 2016, with further increases expected as the climate continues to warm, according to the U.S. government’s National Climate Assessment.
Rain in St. Louis began late Monday as thunderstorms formed along a line from west to east, repeatedly passing over the city like train cars on one track until Tuesday morning. The National Weather Service warned of ‘life-threatening flash flooding’ just after 2 a.m. and later declared a flash flood emergency, its most severe flood alert. By then, 3 to 6 inches of rain had fallen and high water was “threatening homes” while vehicles were submerged in high water, according to the weather service.
“THIS IS A PARTICULARLY DANGEROUS SITUATION,” he warned. “LOOK FOR HIGHER GROUND NOW!”
Saint-Louis received the equivalent of two months of rain in six hours. A stream in St. Peters, Mo., just northwest of St. Louis, rose 21.5 feet in seven hours to a record-breaking crest in the middle of the stream.
The thunderstorms formed along the northern edge of a widespread heat dome over the south-central states, responsible in recent days for record high temperatures in parts of Texas, Oklahoma and Arkansas. St. Louis was located in the turbulent transition zone between this oppressive heat and the cooler weather entering the Upper Midwest from Canada.
On Tuesday, the Weather Service said the area from eastern Missouri to central West Virginia was at high risk of excessive rainfall, with the greatest risk coming from the St. Louis area of southern Illinois. and southwestern Indiana. This risk should travel to the area from southeast Missouri to West Virginia on Wednesday and Thursday.