Why No Tornado Warning Before Tuesday's Twister in the South Suburbs?

The National Weather Service’s Chicago office is getting some grief on Facebook for not issuing a Tornado Warning prior to Tuesday afternoon’s severe storm in the south suburbs, which was classified on Wednesday as an EF-0 tornado.

The twister touched down in Summit and tore a path of about four-tenths of a mile just west of Harlem Avenue at 1:08 p.m. The tornado marked a path close to Argo High School. Rooftops, trees and cars were damaged.

“Looks like it dropped directly in front of our H.S.! Thank goodness it wasn’t dismissal time or a larger tornado. No warning sirens here either,” said one Facebook commenter.

“I saw decent rotation there on RadarScope and couldn’t figure out why no warning was issued. No reason why it shouldn’t have been,” said another.

» RELATED: A Tornado Hit the South Suburbs Tuesday. Really!

Why didn’t the NWS issue a Tornado Watch or Warning? The agency explained on its Facebook page Wednesday.

“Even if a tornado warning would have been possible ahead of time, it may have been a disservice for a weak and short-lived event like this, needlessly sending tens of thousands of people to their basements and triggering emergency response plans at hospitals, schools, and businesses for something that affected a very tiny area and was over by the time most people would have received the message. If we do this too often, people may fail to heed NWS warnings when a truly life-threatening situation develops. NWS tornado warnings in advance of large, long-lived, strong tornadoes have saved countless lives over the past 50+ years. For weak, short-lived tornadoes, it can be extremely difficult to issue warnings far enough in advance to prompt a correct response before the event is over. Yesterday’s tornado was never visible on our NWS Doppler radar (forming and dissipating between scans), and was apparent on the O’Hare FAA Doppler radar for 2-3 minutes at most. Fortunately, we were well aware that conditions yesterday were not conducive for significant tornadoes, but had mentioned in our discussions and outlooks that brief and weak tornadoes were possible.”

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