The Tornado Condition Index (TorCon) is a scale developed by meteorologist Dr. Greg Forbes for The Weather Channel to communicate the risk of tornado activity. The index provides a simplified threat assessment on a scale from 1 to 10. A rating of 9 signifies an extremely high and rare threat level, indicating conditions are highly favorable for significant tornado development within a specific region. This elevated risk demands immediate public awareness and preparation.
Defining the TorCon Scale
The TorCon system is a proprietary forecasting model, not an official index used by the National Weather Service (NWS) or NOAA. It provides the public with a straightforward metric for tornado risk. The index ranges from 1 to 10, with each number corresponding to a 10% chance of a tornado forming within a 50-mile radius of any given point in the forecast area.
Lower numbers, such as 1 or 2, represent a minimal probability of tornadic activity. A reading of 5 indicates a 50% chance of a tornado. The TorCon system uses atmospheric ingredients like wind shear, instability, and lift to determine the score, reserving higher numbers for days when these factors align perfectly for rotating thunderstorms.
Significance of a Level 9 Rating
A TorCon 9 rating translates to an approximately 90% probability of a tornado developing within 50 miles of any location in the designated area. This high likelihood signifies that the atmospheric environment is exceptionally conducive to severe tornadic storms. The rating suggests a strong potential for numerous, long-track tornadoes capable of producing extensive damage.
A Level 9 often aligns with the threat level that prompts the Storm Prediction Center (SPC) to issue a Particularly Dangerous Situation (PDS) Tornado Watch. This rare alert conveys a life-threatening threat with an increased risk of multiple strong tornadoes (EF2 or higher). Forecasters anticipate the possibility of violent tornadoes, such as EF4 or EF5, which cause catastrophic damage and are responsible for the majority of fatalities. Level 10 is reserved for historic, near-certain, catastrophic outbreaks.
Immediate Safety Measures
When a TorCon 9 is issued, take immediate steps to ensure safety before any warning sirens sound. Identify the safest place in your home, typically a basement or a storm cellar. If an underground shelter is not available, the lowest floor’s most interior room, like a closet or bathroom away from windows, is the next best option.
You need multiple ways to receive time-sensitive weather alerts. A NOAA weather radio is recommended as it operates independently of cell service or power grids. Cover your head and neck with your arms or use a helmet, and shield yourself with a mattress or heavy blanket to protect against flying debris, the leading cause of injury in a tornado.