What is the difference between a tornado watch and a warning?

This distinction can genuinely save your life, and people mix it up constantly. A tornado watch means conditions are favorable for tornadoes to develop in your area, the atmospheric ingredients are coming together, so you should stay alert, keep an eye on the weather, and be ready to act. A watch typically covers a large area for several hours. A tornado warning is far more urgent: it means a tornado has actually been spotted or is showing up on weather radar in your immediate area, so you should take shelter immediately, there is an active, imminent threat right now. A warning covers a smaller area for a shorter time, because it means the danger is real and close.

A memory trick that sticks: think of making chili. A watch is when you have gathered the ingredients on the counter, the conditions are right to cook, but nothing is on the stove yet, so you watch and stay ready. A warning is when the pot is boiling over, it is actually happening, so you act now. The same watch-versus-warning logic applies to severe thunderstorms, flash floods, and other hazards: watch means be prepared, warning means take action. When a tornado warning is issued for your location, the correct response is to get to the safest place available immediately, an interior room on the lowest floor, away from windows, a basement or storm shelter if you have one, and cover your head, rather than going outside to look for the tornado, which people dangerously tend to do. So the clean version: watch means be ready (conditions are right), warning means take cover (it is here or imminent), and knowing the difference means knowing whether to stay alert or to move now.