While there is no single agreed upon definition, generally more than six tornadoes in a day in the same region is considered a tornado outbreak. A series of continuous or near continuous tornado outbreaks is a tornado outbreak sequence.

The biggest tornado outbreak on record — with 148 tornadoes, most significantly including six F5 and 24 F4 tornadoes — occurred on April 3-April 4, 1974 across the United States and Canada. It is dubbed the Super Outbreak.

See also

• List of tornadoes and tornado outbreaks

References

• Edwards, Roger, Richard L. Thompson, Casey Crosbie, John A. Hart, and Charles A. Doswell III (2004). "Proposals for modernizing definitions of tornado and severe thunderstorm outbreaks". 22nd Conference on Severe Local Storms, American Meteorological Society.
• Forbes, Gregory S. (2006). "Meteorological aspects of high-impact tornado outbreaks". Symposium on the Challenges of Severe Convective Storms, American Meteorological Society.
• Galway, Joseph G. (1977). "Some Climatological Aspects of Tornado Outbreaks". Monthly Weather Review, 105 (4).
• Grazulis, Thomas P. (1993). Significant Tornadoes 1680-1991, A Chronology and Analysis of Events. The Tornado Project of Environmental Films. ISBN 1879362031
• Schneider, Russell, Harold E. Brooks, and Joseph T. Schaefer (2004). "Tornado Outbreak Day Sequences: historic events and climatology (1875-2003)". 22nd Conference on Severe Local Storms, American Meteorological Society.
• Schneider, Russell, Joseph T. Schaefer, and Harod E. Brooks (2004). "Tornado Outbreak Days: an updated and expanded climatology (1875-2003)". 22nd Conference on Severe Local Storms, American Meteorological Society.
• Thompson, Richard L. and M.D. Vescio (1998). "The Destruction Potential Index – a method for comparing tornado days". 19th Conference on Severe Local Storms, American Meteorological Society.
• Verbout, Stephanie M., Harold E. Brooks, Lance M. Leslie, David M. Schultz (2006). "Evolution of the U.S. Tornado Database: 1954-2003". Weather and Forecasting, 21 (1).

Tornado