The NOAA’s Storm Prediction Center issues daily severe thunderstorm forecasts, categorizing threat levels from “marginal risk” to “high risk.” These forecasts cover the next eight days and indicate areas at risk of severe weather events within 25 miles. Factors considered include satellite and radar imagery, weather model output, pattern recognition, and forecaster expertise. Collaboration among forecasters ensures comprehensive outlooks. Severe weather entails wind gusts over 58 mph, wind damage, hail over one inch, or tornadoes. Excessive rainfall and flooding risks are not included in these forecasts. Lightning and flooding can be as deadly as tornadoes. The outlook scale ranges from “Marginal Risk” with isolated severe storms to “Enhanced Risk” with numerous severe thunderstorms likely. The “Moderate Risk” category indicates widespread severe thunderstorms, including tornadoes, large hail, and damaging winds.
High Risk – Category 5
This level of risk is uncommon and is typically only used when supercells are capable of producing strong tornadoes or when long-lived squall lines are expected to bring widespread damaging winds. These high-risk alerts are issued only a few times a year.
During a high-risk event, widespread severe thunderstorms are anticipated. A severe weather outbreak is expected, with the potential for multiple tornadoes and/or a destructive long-lived derecho. Significant damage is anticipated. Tornadoes that do form in the area are expected to be strong (EF2+) or violent (EF4+) and/or long-tracked.
The Storm Prediction Center (SPC) designates a high risk when there is a high level of confidence in the widespread occurrence of severe weather, including instances of extreme severity. While not every location within a high-risk area will necessarily experience severe weather, communities in these areas typically have a 30% or higher chance of encountering severe storms.
It is the primary mission of The Weather Company to provide timely reporting on severe weather events, environmental issues, and the significance of science in our daily lives. Please note that the views expressed in this article may not necessarily reflect the stance of our parent company, IBM.
