New Hazardous Weather Warning System Proves its Mettle During March 2025 Tornado Outbreaks

From March 13 to March 16, 2025, a historic and deadly tornado outbreak swept across the central United States, unleashing severe weather from the Gulf Coast to central Illinois. The storm system produced more than 115 confirmed tornadoes, and resulted in $6.25 billion in damage and 23 fatalities, making it one of the largest on record for the month of March.

In Missouri, the Saint Louis National Weather Service (NWS) forecast office found itself at the heart of the storm. Over four days, forecasters issued 20 tornado warnings and 30 severe storm warnings in eastern Missouri and southwestern Illinois, making it one of the most active outbreaks on record for the St. Louis area. Two tornadoes were rated EF-3, with peak wind speeds in excess of 150 mph. Only one injury and no fatalities were reported in the St. Louis forecast area.

By any measure this was a challenging system to forecast, but issuing life-saving warnings during this extended period of severe weather was made faster and easier by a new tool called Hazard Services Convective, developed by NOAA’s Global Systems Laboratory (GSL) in Boulder, Colorado.

“Using Hazard Services is more intuitive, which allows my forecasters to issue warnings more rapidly, as well as giving them the ability to monitor and create multiple warnings simultaneously,” said Ben Herzog, the NWS Science and Operations Officer in the St. Louis forecast office.

Hazard Services Convective is one member of a suite of Hazard Services applications that began rolling into NWS operations in 2019. The suite consists of applications for several different weather and water hazards. The “Convective” application addresses the hazards associated with thunderstorms, such as hail, tornadoes, and wind. The term “convective” refers to the vertical transport of heat and moisture in the atmosphere, especially by updrafts and downdrafts in an unstable atmosphere.