Success & Failures with Tornado Warnings

Nearly three out of four tornado warnings issued by the federal agency today are false alarms, according to internal grading data provided by the agency, a measure that has seen virtually no improvement over the past 20 years. It's a confounding and complicated issue for the agency, which admits that crying wolf 75 percent of the time is by no means an acceptable standard. But it also knows that hesitancy in a potentially life-threatening situation could prove even more costly.

The National Weather Service concedes that the complexity of tornado forecasting makes it hard to find a clear solution.

“I think it points to the fact that we still have a long way to go,” said Greg Carbin, a warning coordination meteorologist at the agency's Storm Prediction Center in Norman, Oklahoma. “You don't want to miss the bad events. Even in the event where we're wrong several times, you would rather have a warning out there and have it miss than have an event and not have one out there.”

This has been the case for decades. Forecast verification data from the weather service over the past two decades shows that for all the advances technology has provided to forecasting, the agency has made only a relatively small dent in how often it's wrong when issuing a tornado warning (from 80 percent in 1989 to 72 percent in 2014).

Carbin said a new challenge for NWS is how to handle the massive quantities of data being produced by rapidly advancing technology when staffing levels are either stagnant or dropping .

Still, technology has led to significant improvements in accurately predicting tornadoes when they do touch down, just not in avoiding false alarms. According to the grading data, the likelihood that a tornado will be spotted by forecasters and accompanied by a warning has improved from just 30 percent in the 1980s to about 70 percent in the last decade. Similarly, the amount of lead time given to the public has grown from just three to four minutes in the '80s to generally 10 to 15 minutes over the past 10 years, providing crucial time for people to reach safety in a situation where seconds can count.

There's also hope that the implementation of dual-polarization radar — which analyzes atmospheric objects on both horizontal and vertical planes — will help the weather service shake the stagnant false-alarm record loose, but its impacts remain to be seen. The new technology was installed at all 160 weather service offices in 2013, but has yet to bear significant results.

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