Spring is often a time of confused weather: warm one day, chilly the next. This kind of unsettled weather can sometimes develop into strong storms, like thunderstorms or tornadoes. Although tornadoes are not as common in the Chippewa Valley as they are in other parts of the Midwest, they do occasionally develop in the area.

Meteorologists use Doppler radar to decide when conditions are right for a tornado to occur. They use that information to alert the public. Using tools and information to guess about what might happen is called making an inference. When meteorologists have inferred that conditions are right for a tornado to develop, they announce a tornado watch.

However useful guesses are, they’re still only guesses. To add to the radar data meteorologists gather about the storms, the National Weather Service also trains and relies on people called storm spotters. Storm spotters are different from storm chasers. Chasers go to areas where a tornado is likely to occur in order to get videos or photos of the storm, either to sell to the news to just for fun because they think extreme weather is interesting.

Storm spotters are volunteers who have been trained by the National Weather Service to watch what the weather does on the ground and report back to meteorologists. This is called “ground truthing,” and it is based on direct observation that confirms inferences and weather predictions. During a tornado watch, storm spotters may look for a funnel cloud or a tornado touch the ground, which would turn the tornado watch into a tornado warning.

Thanks to the advance warning we get from inference based on data and ground truthing, people know when to head inside and stay safe during a storm.