Tornadoes are extremely violent local storms that form when a whirling vortex of air develops inside of a severe thunderstorm and lowers to the ground. You'll recognize a tornado by its distinctive funnel cloud shape.
Tornadoes can appear any time of year, but are most common during the spring and summer months.
The best evidence of a tornado is often the devastation and destruction on the ground. The wicked winds of strong tornadoes will destroy anything in their path. The resulting destruction is the storm's signature.