CHESTERFIELD, Mo. — Severe storms kept St. Louis area residents up late Monday night as torrential rain, hail and wind caused issues across the region.
Potential tornado damage was reported in both St. Louis and St. Francois counties, and National Weather Service teams are surveying the area to confirm whether a tornado did actually form.
NWS confirmed with 5 On Your Side Tuesday morning that preliminary investigations found a tornado touched down in the heart of Chesterfield. The survey team estimated that the tornado's gusts were between 65 and 85 mph, was on the ground for 2 miles and had a max width of 332 yards.
Below is a screenshot of the tornado's path:
Tornado investigations near the area of Bonne Terre, Missouri, and Chester, Illinois, are ongoing.
How do meteorologists figure out whether a tornado happened or not? Radars and electronics can only tell NWS meteorologists so much. To figure out whether a tornado happened, the service has to head out into the field. Just over 24 hours after the storms, the agency sent out multiple survey teams to assess damage and figure out whether a legitimate tornado touchdown occurred.
"The pattern of damage determines if it was a tornado. NOT how much damage was caused," NWS said on its website. "We conduct surveys to find out exactly what happened. This helps us to improve our warnings for the future. This is also important for historical reference."
Tornado damage can often be confused with damage from a microburst, so meteorologists look at the type of damage, rather than how much damage occurred.
Damage from a tornado often looks chaotic and leaves large trees uprooted and often crossing each other on the ground, the service said. Smaller snapped branches or trees aren't usually helpful, since those don't convey the true severity of winds.
For example, NWS originally said in a tweet on March 14 that a tornado was confirmed near Maeystown, Illinois. However, around half a dozen surveyors went to the area the next day and couldn't find any damage indicating a tornado was in the area.
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