NSSL Research: Tornadoes

Much about tornadoes remains a mystery. They are rare, unpredictable and deadly. The U.S. has more tornadoes than anywhere else in the world. NSSL's tornado research targets ways to improve tornado forecasts and warnings to help save lives.

Tornado Research Areas


NSSL participated in the Verification of the Origins of Rotation in Tornadoes EXperiment 2009-2010 (VORTEX2), the largest tornado research project in history to explore how, when and why tornadoes form. The National Oceanic and Atmospheric Administration (NOAA) and National Science Foundation (NSF) supported more than 100 scientists, students and staff from around the world to collect weather measurements around and under thunderstorms that could produce tornadoes. We continue to study the vast amounts of data to learn what specific ingredients thunderstorms need to form a tornado, what causes it to die, and why some rotating thunderstorms produce tornadoes and others do not.

Tornado Dynamics

NSSL researchers have created a computer model that simulates a tornado-producing thunderstorm in 3-D. We use this model to study what changes in the environment cause a thunderstorm to produce a tornado, and how the tornado and storm behaves as it encounters different weather conditions.

Most tornadoes come from rotating thunderstorms, called supercells. However, a nearly 20% of all tornadoes are associated with lines of strong thunderstorms called “quasi-linear convective systems” (QLCS). QLCS tornadoes frequently occur during the late night and early morning hours when the public is less aware of severe weather hazards. We are looking for ways to detect non-supercell tornadoes more effectively.

Tornado Detection

The national network of weather radars now use dual-polarization technology, and NSSL continues to be a leader and major contributor to its ongoing scientific and engineering development. NSSL researchers discovered dual-polarization radars can detect debris from a tornado, helping forecasters pinpoint its location even at night or if it is wrapped in rain.

NSSL has a research phased array radar that can scan the entire sky for severe weather in less than a minute, five times faster than current weather radars. This phased array radar has been used to capture developing tornadoes both in QLCS's and supercells. Researchers are hoping to collect more high-resolution data on these storms to look for clues on radar that a tornado is forming. Phased array radar has strong potential to aid the NWS in the forecast and warning decision process by providing new radar data more quickly.

Tornado Warning Decision Support

NSSL continues to work on an automated multi-radar, multi-sensor (MRMS) system that quickly integrates data streams from multiple radars, surface and upper air observations, lightning detection systems, and satellite and forecast models. The MRMS system was developed to produce severe weather and precipitation products for improved decision-making capability within NOAA.

NSSL's On-Demand web-based tool that helps confirm when and where tornadoes may have occurred by mapping circulations detected by radar on Google Earth satellite images. NWS forecasters can quickly review warnings and check their accuracy with this system. Emergency responders and damage surveyors have also used On-Demand to produce high-resolution street maps of affected areas, so they can more effectively begin rescue and recovery efforts and damage assessments.

NSSL and the NOAA National Weather Service collaborate to streamline moving research into practical operations. NSSL has developed severe weather warning applications and decision support systems that will make the forecasters job easier. The result will be improved NWS warning services for the public, increased detection accuracy, and longer lead times.

Tornado Forecasting

NSSL's Warn-on-Forecast project aims to create highly detailed computer weather forecast models that predict what the atmosphere will look like in the future. These models are unique because they will use the latest weather observations and radar scans to continuously re-compute forecasts. We want these forecasts to accurately predict when and where tornadoes will occur in the next hour so forecasters can issue warnings based on that forecast and give people more time to find shelter.

Tornado Preparedness

We are very involved in shaping a “Weather Ready Nation” to improve the public's preparedness for extreme weather. We are looking at ways to improve the forecast and warning system, communicate threats to the public, increase community resilience, and identify gaps in our current understanding of planning, coordination and decision-making in a community.

Tornado Climatology

Tornadoes can happen at any time of day at any time of the year. An NSSL scientist developed the Severe Thunderstorm Climatology to estimate the likelihood of severe weather events such as tornadoes on a given day in the U.S.

Past Tornado Research

May 24, 1973—Tornado Vortex Signature identified

An NSSL team intercepts a storm being scanned by the NSSL Doppler radar. The team documents the entire life cycle of a tornado on film. Researchers are able to compare the film images with Doppler radar data and discover a pattern that meant the tornado was forming before it appeared on film. They name this pattern the Tornado Vortex Signature (TVS). This important discovery eventually caused NOAA to begin a nationwide deployment of a national network of Doppler radars.

1975—Tornado Intercept Project

NSSL's legacy in organized field experiments begins with the Tornado Intercept Project in 1975 led by NSSL's Bob Davies-Jones. NSSL's Don Burgess provided storm intercept crews with live radar information via radio – and the term “nowcaster” was born.

1976—Joint Doppler Operational Project

NSSL conducts the Joint Doppler Operational Project (JDOP) in 1976 to prove Doppler radar could improve the nation's ability to warn for severe thunderstorms and tornadoes. This led to the decision in 1979 by the National Weather Service (NWS), U.S. Air Force's Air Weather Service, and Federal Aviation Administration (FAA) to include Doppler capability in their future operational radars.

1981–1984—Totable Tornado Observatory

NSSL attempts to deploy TOTO, the TOtable Tornado Observatory in the path of an oncoming tornado from 1981-1984. They are unsuccessful.

1995—The First VORTEX Project

The Verification of the Origins of Rotation in Tornadoes EXperiment (VORTEX) was a two-year project designed to answer a number of ongoing questions about the causes of tornado formation. A new mobile Doppler radar was used and provided revolutionary data on several tornadic storms. You can read more about the history of the VORTEX projects at NSSL and see an interactive, multimedia timeline on the VORTEX @ NSSL page.


NSSL and OU conduct VORTEX-99, a small follow-on project to the original VORTEX. VORTEX-99 is operating when an F5 tornado tore through parts of south Oklahoma City on May 3, 1999. During the deadly outbreak, NWS forecasters rely on NSSL's Warning Decision Support System (WDSS) to make timely and accurate tornado warnings.