Assessing Severe Weather Risks
“Slight” and “marginal” risk of severe weather used on your weather maps. What’s the difference?
Carol Hausmann Tinley Park
The Storm Prediction Center in Norman, Oklahoma issues several daily severe weather outlooks assessing the severe weather risk, not only for the current day, but for up to eight days in advance. The risk is evaluated on a graduated scale from no risk at all to a high risk that a severe weather event will occur within 25 miles of a location. The definitions- General thunderstorms- no severe, Marginal- isolated, Slight-scattered- Enhanced-numerous- Moderate- widespread and High- widespread and particularly intense. All thunderstorm categories imply an inherent risk of lightning and flooding rains, and case-specific forecasts are made for high wind speed, hail size and tornado intensity for severe thunderstorms.