ST CHARLES, Mo. — Residents across the St. Louis region had a quick scare late Monday night after tornado warnings were issued in St. Charles and Lincoln counties.
National Weather Service survey crews deployed the next morning to assess the damage caused by the storm system that drenched the region. The survey crews traveled to areas where damage was reported to confirm whether suspected tornadoes touched down.
Where did a tornado touch down in the St. Louis region?
The NWS confirmed one tornado touchdown in the St. Louis region from the storms.
The tornado touched down in northwestern St. Charles County just after 9:30 p.m. with a max wind speed of 75 mph. The tornado was on the ground for over 6 miles, damaging several trees, a pole barn, and a nearby residence before it crossed Highway 61 into Warren County and dissipated.
Editor's note: "St. Louis region," as used in this article, refers to the St. Louis County Warning Area (CWA), the region that the National Weather Service's St. Louis office covers, rather than the "St. Louis metro area." Tornadoes rarely touch down in what is considered the St. Louis metro area. For example, of the 1212 confirmed tornadoes in the St. Louis region from 1805 to 2023, only 54 have touched down in St. Louis County.
How do meteorologists confirm tornado touchdowns?
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. Less than 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," the 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 This is also important for historical reference."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, the NWS originally said in a tweet on March 14 that a tornado was confirmed near Maeystown, Illinois. However, about half a dozen surveyors went to the area the next day and couldn't find any damage indicating a tornado was in the area.
