Tornado
A tornado is a rotating column of air extending from the base of a cumuliform cloud and often visible as a condensation funnel in contact with the ground, and/or attendant circulating dust or debris cloud at the ground (WMO, 2017).
Primary reference(s)
WMO, 2017. International Cloud Atlas: Tornado. World Meteorological Organization (WMO). Accessed 25 November 2019.
Annotations
Additional scientific description
A large tornado in which the condensation funnel is at least as wide horizontally at the ground as it is in height from the ground to the cloud base may be referred to as a wedge tornado. During the dissipation stage of a tornado, the condensation funnel will shrink and narrow in width, becoming rope-like (a rope funnel), and may also become contorted. Some tornadoes may contain secondary vortices within the main circulation (suction vortices or subvortices) (WMO, 2017a).
Metrics and numeric limits
Tornadoes can be classified into the following distinct formation groups (WMO, 2017b): Type I (in association with supercells; WMO, no date), Type II (in association with quasi-linear convective systems), and Type III (localised convective and shear vortices - these comprise landspouts, waterspouts, and cold-air funnels).
Definitions for the Type III tornadoes are as follows (WMO, 2017b):
- Landspout: A tornado that does not arise from organised storm-scale rotation and is therefore not associated with a wall cloud (murus) or a mesocyclone.
- Waterspout: A tornado occurring over water. It is normally a relatively small, weak rotating column of air over open water below a Cumulonimbus or Cumulus congestus cloud.
- Cold-air funnel: A funnel cloud or (rarely) a small, relatively weak tornado that can develop from a small shower or thunderstorm when the air aloft is unusually cold.
The strength of a tornado is commonly estimated based on the extent and type of damage it causes. Various scales have been developed worldwide to classify tornado intensity, reflecting regional differences in damage patterns and assessment practices. The Enhanced Fujita (EF) Scale, introduced by the Storm Prediction Center (SPC) (2017a, n.d.), is the most widely used and has been adapted for use in countries such as Australia, South Africa, Canada, and Japan. In Europe, meteorological services typically employ the International Fujita (IF) Scale, as outlined by the European Severe Storms Laboratory (ESSL) in August 2023.
Key relevant UN convention / multilateral treaty
Sendai Framework for Disaster Risk Reduction 2015-2030.
Drivers
No information Available
Impacts
Impacts of tornadoes: Tornadoes have significant effects on human activities and communities, with the extent of tornado damage as a key component to the rating and wind speed estimations of tornado events (NOAA, 2024).
Impacts on Human Lives and Communities: Tornadoes pose severe risks to human life and safety due to their intense winds. Fatalities and injuries result from flying debris, structural collapses, and vehicles being overturned. According to the National Oceanic and Atmospheric Administration (NOAA), tornadoes caused an average of 71 fatalities annually in the United States (U.S.) between 1993 and 2022. Spring 2011 marked one of the deadliest tornado seasons recorded in the U.S., with over 580 people killed from April to June 2011, with the high death toll partly attributed to the rapid speed of the tornadoes that struck heavily populated areas with inadequate storm shelters (NOAA, 2024).
Damage to Infrastructure and economy: The economic costs of tornadoes are immense, with damages worth millions, and in some cases billions, per event. Tornadoes can cause significant damage to critical infrastructure, and can destroy homes, businesses, schools, and hospitals, creating significant challenges for rebuilding and recovery. For example, the EF-5 tornado that struck Joplin, Missouri, in 2011, caused losses of almost $3 billion, making it one of the costliest tornadoes in U.S. history (NIST, 2011). The 2011 Joplin tornado “damaged 553 business structures and nearly 7,500 residential structures; over 3,000 of those residences were heavily damaged or completely destroyed” (NIST, 2011).
Multi-hazard context
The figure below summarises common interactions between tornadoes and other hazards. This information should be used with caution and not be solely relied upon in Disaster Risk Management, particularly as some interactions may not have been included. Note that hazardous events occurring together or locally in space or time may not necessarily cause, amplify, or be otherwise related to each other. Specific examples of multi-hazard context can be found in the ‘Hazard drivers’ and ‘Impacts’ sections above.
Multi-hazard diagram
Risk Management
Since the advent of Doppler Radar, lead times for tornado warnings have increased from when a tornado first touches the ground to upwards of 14 to 20 minutes or more beforehand (WMO, 2017b; National Geographic, 2019).
Monitoring
The section above and the table below offer an overview of monitoring tornadoes. This information can be used for forecasting within a national early warning system (EWS). Since EWS capacities and processes differ across countries, the most current and specific information regarding EWS should be obtained from the appropriate national or regional agency/authority responsible for disaster management.
| Which institution(s) produce(s) Disaster Risk Data/Information? |
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| How is the Hazard Observed/Monitored/Forecast? | Tornadoes are monitored using Doppler radar, satellites, and ground-based weather stations to track storm rotation, wind speeds, and atmospheric pressure changes. Meteorologists analyse temperature differences, wind shear, and thunderstorm activity to predict tornado formation. Advanced computer models simulate storm behaviour, helping forecasters issue early warnings. These warnings assist emergency responders, communities, and infrastructure managers in preparing for potential destruction from high winds and flying debris. |
References
European Severe Storms Laboratory (ESSL), 2023. The International Fujita (IF) Scale for Tornado and Wind Damage Assessments. 1 August. Accessed 16 May 2025.
National Geographic, 2019. What we know – and what we don’t – about the science of tornadoes. Accessed 16 May 2025.
National Institute of Standards and Technology (NIST), 2011. Joplin Missouri Tornado 2011. Accessed 16 May 2025.
National Oceanic and Atmospheric Administration (NOAA), 2024. Tornadoes. U.S. Department of Commerce. Accessed 16 May 2025.
Storm Prediction Center (SPC), 2017a. The Enhanced Fujita Scale (EF Scale). Accessed 16 May 2025.
World Meteorological Organization (WMO), no date. Glossary: Supercell. World Meteorological Organization (WMO). Accessed 16 May 2025.
World Meteorological Organization (WMO), 2017a. International Cloud Atlas Manual on the Observation of Clouds and Other Meteors. WMO-No. 407. World Meteorological Organization (WMO). Accessed 16 May 2025.
World Meteorological Organization (WMO), 2017b. Guidelines for Nowcasting Techniques. WMO-No. 1198. World Meteorological Organization (WMO). Accessed 16 May 2025.