A tornado warning is issued when:

• a tornado is reported on the ground,
• a funnel cloud is reported in the sky,
• a waterspout is headed toward landfall, or
• a thunderstorm with strong rotation is indicated by doppler radar.

A tornado warning means there is immediate danger for the warned area -- if not from the relatively narrow tornado itself, from the severe thunderstorm producing (or likely to produce) it. Everyone in the path of such a storm is advised to take cover immediately, as it is likely a life-threatening situation.

In the United States, the National Weather Service issues warnings for tornados and severe thunderstorms on a per-county basis.

A warning must not be confused with a tornado watch.

External links

• NWS - Tornado Warning Guideance: Spring 2002 (72kb PDF)