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Changes are in store for National Weather Service severe weather threat levels

If you pay attention to weather forecasts, you might notice a few new terms making their way into storm predictions. The National Weather Service’s Storm Prediction Center is adding two new categories to its list of threat levels.
by Silas Allen Modified: August 13, 2014 at 2:00 pm •  Published: August 12, 2014

For example, a 2 percent chance of a tornado might not sound threatening to most people, he said, but any chance greater than 0 percent could be a cause for concern. Categorical threat levels like “marginal risk” and “slight risk” can be more helpful for people who are trying to plan for severe weather.

But those categorical threat levels are imperfect and can lead to confusion, as well, Carbin said. The “slight risk” category was meant to explain that a chance for severe weather existed, but the storm was too scattershot or isolated to predict with much certainty which towns or neighborhoods would be affected, he said. So a thunderstorm or tornado would occasionally take residents by surprise on “slight risk” days.

“The word ‘slight’ doesn’t convey the right message when it comes to severe weather,” he said. “What we want to do is better define that ‘slight’ in terms of risk.”