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High Risk: What Does That Mean?

March 26, 2021
By WeatherBug Meteorologist, Andrew Rosenthal
The government's Storm Prediction Center has issued a High Risk of severe thunderstorms. What does this mean?

The Storm Prediction Center uses a five-point scale of thunderstorm potential, ranging from Slight to High Risk, with High Risk being the top of the scale. This means that there is a likely chance for extremely dangerous thunderstorms to develop.

"High Risk" forecasts are quite rare, issued on average only once or twice a year. Typically, High Risk areas are issued when a particularly strong and widespread severe storm or tornado outbreaks are expected. These correspond to areas that strong tornadoes are likely to develop.

Threats to areas in a High Risk typically include:
  • The likelihood of tornadoes, often strong and/or long-lasting
  • Frequent lightning
  • Damaging winds, often in excess of 80 mph, and lasting hours at a time such as in a derecho
  • Likelihood of structural damage from storms
  • Large hail in excess of 2 inches
When a High Risk area is issued, it should be taken very seriously. Its presence means that government forecasters are very confident that widespread storms will develop, and that these storms are capable of causing significant damage or even causing fatalities.

High Risk areas have been issued prior to many recent infamous tornado outbreaks, with areas such as Joplin, Mo., and Tuscaloosa, Ala., under High Risks in 2011.

For anyone in a High Risk area, it would be wise to keep an eye on the sky during any activities, and be prepared to take shelter at a moment's notice. Make sure that you download the WeatherBug app on your smart phone before you head out on any outdoor activities.

 Image: Storm Prediction Center map the afternoon of April 2, 2017 for the Lower Mississippi Valley. High Risk for eastern Texas and Louisiana. (NOAA)