The National Weather Service communicates tornado risks on a three-tier system

Explore tips from the American Red Cross on preparing for a tornado

If you live in a region prone to tornadoes, have a plan to retreat to a safe room built to withstand strong winds, such as an underground shelter or a windowless room at the lowest level of a study building, in case of a tornado warning. Having a stay-at-home kit with non-perishable food and water, medications, batteries and chargers, and a battery-powered radio is also essential.

Most tornadoes occur during the afternoon and evening hours

While there is no official national tornado season as with Atlantic hurricanes, many tornadoes form in the presence of thunderstorms, which are fueled by solar heating and the energy released by the condensation of water vapor. The airflow instabilities created from this energy build throughout the day until the sun sets.

Fast-changing conditions during their formation make tornado forecasting difficult

The final steps of tornadogenesis—the process of forming a tornado—depend on near-surface details, such as local geography, which are difficult for radar to observe and affect how funnel clouds make contact with the ground. Inconsistencies in storm behavior have limited the amount of advance warning people receive before tornadoes touch down.

In a tornado outbreak, a single severe weather system can spawn multiple twisters

By maintaining the ingredients for tornadoes—differences in wind speed and direction across altitudes, moisture, and rising air—for long periods of time as it moves across a region, a severe thunderstorm can continuously produce tornadoes by lifting multiple columns of horizontally rotating air.

Within an 18-hour period in 1974, 13 states were hit by 148 tornadoes

From April 3-4, a tornado outbreak killed over 300 people and caused $600M in damage ($3.8B in 2024 dollars). The event revealed deficiencies in various technologies, including crude radar imaging and slow typewriter-based communication systems, which quickly bottlenecked and became outdated as tornado watches became tornado warnings.

Tornadoes produce inaudible signals to humans hours before forming

Researchers at the National Oceanic and Atmospheric Administration have found that tornado-producing storms generate specific sounds below the range of human hearing, much like the infrasonic signals produced by earthquakes and avalanches. Although difficult to distinguish from wind noise, scientists hope to build systems that use these signals to improve tornado forecasting.

Unlike hurricanes, tornadoes are not ranked based on measured wind speed

Technological limitations prevent direct measurements of wind speeds where tornadoes make contact with the ground. Instead, the Enhanced Fujita scale assigns a rating with a range of speeds based on how much damage a tornado caused to various types of structures. These types are more extensive than the original Fujita scale.

Tornado chasers include scientists conducting field projects

Research teams use drones, mobile weather stations, and radar systems to capture real-time meteorological data, better understand conditions that favor tornado formation, and improve forecasting models. As of 2022, model limitations result in roughly 70% of tornado warnings being false alarms.

Tornado myths include suggestions to hide beneath a bridge or to open windows

Winds can accelerate due to a tunneling effect as they pass under a structure, making seeking shelter from a tornado in a mobile home or recreational vehicle highly discouraged. Significant tornado damage results from debris being picked up and hurled by strong winds, making it unsafe to be near windows that may shatter.

Tornadoes, or twisters, have been seen on every continent but Antarctica

Because tornadoes require rising warm air to form, some meteorologists have suggested that urban environments—locations where human landscape modification has introduced materials that trap thermal energy—can enhance the conditions needed for tornado formation. Tornadoes have been reported to cause ear "popping" due to drastic changes in air pressure.

Various types of tornadoes are distinguished by their shape, size, and location

Waterspouts form over water as long, thin columns of mist and air, while elephant trunks are tornadoes that elongate vertically as they become tilted during their formation, resembling the mammal's appendage. Wedge tornadoes are among the most powerful, often spanning a mile or more in width.

Tsunamis can last for days as their successive waves hit a coastal area, with early warning systems indicating the likelihood of a tsunami's arrival on a scale from watch to advisory to warning.

Watch the birth of a tornado in real time

While driving through suburban Oklahoma in May 2013, National Geographic explorer and storm researcher Tim Samaras witnessed the formation of a tornado from a thunderstorm and captured footage of the descending funnel cloud before it touched down.

Tornado formation relies on wind shear to create a tube of rotating air

Once a horizontal vortex is created by air circulating between winds of different directions and speeds, an updraft, such as those seen in powerful thunderstorms, tilts the vortex vertically. The updraft then strengthens the vortex, which becomes a tornado upon touching the ground.

Though less common, tornadoes can form without the presence of thunderstorms

Supercell tornadoes involve rising warm air—updrafts—from the strongest type of thunderstorm—supercells—to help turn horizontally rotating tunnels of air into vertical columns. In non-supercell tornadoes, which are generally weaker as a result of forming within less energetic systems, vertical rotation is present from the start near ground level.

Stretching from Texas to the Dakotas, Tornado Alley is a US tornado hotspot

The region experiences atmospheric instability and extensive wind shear due to the convergence of warm, moist air from the Gulf with cooler, drier air from the Rockies. However, some recent data suggests tornadoes are more frequent and more powerful in the Dixie Valley, which includes much of the lower Mississippi Valley.

The way hurricanes are categorized may mislead the public to their dangers

The Saffir-Simpson scale categorizes hurricanes based on wind speed, but tropical cyclones' main dangers are storm surges and heavy rainfall. To better communicate risks to the public, a new system that incorporates hurricane size, water content, and other complexities should be developed.

The ingredients that make up severe weather

A seven-minute video illustrating how a storm is made. These factors—moisture, instability, lift, and shear—are explained through a series of data sets and creative, descriptive diagrams.

Visualizing the year in US tornadoes, 2024

Between January and November 2024, over 1,700 tornadoes were documented to have touched down in the US, a relatively high number (and similar to the numbers in 2004, 2008, and 2011). This map shows their location across the country to help capture the number.

Hurricanes are classified according to their maximum sustained wind speed

The Saffir-Simpson Hurricane Wind Scale is a rating system that organizes hurricanes into one of five categories. Categories three and higher are classified as major hurricanes, but all categories can produce deadly storm surges and rain-induced floods.

Tornadoes can cause significant air pollution and diminish air quality

Asbestos, a hazardous material that can cause lung cancer, is commonly found in buildings constructed before 1980. Tornadoes that damage such buildings can release asbestos into the air, along with other toxic pollutants and dust as materials are lifted. Individuals, particularly those with asthma or other chronic lung diseases, are encouraged to wear masks after a tornado.

Learn all about different types of extreme weather

Find out in more detail about different types of extreme weather, from flooding to thunderstorms, from tropical cyclones to sandstorms, and more (w/ helpful videos).

The first known instance of a fire tornado occurred in 2003

During pyro-tornadogenesis, many processes that create thunderstorms from wildfires, such as rising hot air and steam from evaporated water in forests, fuel the formation of a fire tornado. The increasing rates of wildfires due to climate change are expected to make this phenomenon and other extreme weather more common.

The risk of tornadoes and storm surges is greatest on the 'dirty side' of a hurricane

Winds in the right-front quadrant of the storm are amplified by the hurricane's motion and its rotation, which both move air in the same direction. Upon making landfall, these winds pull water from the Gulf and Atlantic onto land, creating storm surges. Tornadoes can also be generated from large differences in wind speed and direction at various heights.

Tropical cyclones consist of three main parts: the eye, the eyewall, and rainbands

The eye is a calm, clear central area surrounded by an eyewall of intense thunderstorms. Rainbands are spiral bands of clouds and thunderstorms extending from the eyewall.

In Doppler radar imaging, a 'hook echo' helps identify a tornado-producing thunderstorm

Typically found in the right-rear part of a storm relative to its motion, the "hook" is the hallmark of a mesocyclone—a large, rotating updraft of air—within supercells, the most powerful thunderstorms. While tornadoes are known to develop within mesocyclones, they can also be detected by storm spotters trained to recognize tornado conditions in their communities.

Explore the effects of tornadoes of different scales

In this simulation, users can adjust the tornado's diameter and rotation speed to see its impact as it passes through a series of trees and a one-story home.

Scientists use ground-based radar data to detect turbulence within clouds

NCAR developed the NEXRAD Turbulence Detection Algorithm and the Graphical Turbulence Guidance system to provide forecasts up to 18 hours ahead using ground-based Doppler radar data. Software systems also utilize an automated observation and reporting package—the EDR system—found on Delta, United, and Southwest Airlines aircraft.

Track active wildfires, floods, and other natural disasters across the US in real time with this interactive map.

View the ten deadliest tornadoes in US history.

Rather than predicting them in advance, earthquake early warning systems detect tremors moments after they begin and send notifications that reach users before the seismic activity does.

Pilots are familiar with multiple types of turbulence, each with varying severity

Each type is defined based on what disrupts airflow in the atmosphere, including thunderstorms, mountains, and wakes produced by aircraft that previously took off. Pilots classify turbulence as light, moderate, severe, or extreme based on how it affects aircraft movement.

A list of common questions and answers about hurricanes from NOAA

This FAQ answers many questions hurricane researchers at NOAA have received, sorted by category. The answers provide insights into hurricane classification and naming, forecasting their movement and growth, and tips for preparing ahead of landfall.

A teenager survived being flung a world-record 1,307 feet by a tornado

On March 12, 2006, 19-year-old Matt Suter was lifted into a tornado while inside a mobile home in Fordland, Missouri. Despite traveling 1,307 feet, his only significant injury was a head wound caused by being hit by a lamp prior to being transported.

What does the hurricane forecast cone really tell us?

Ever feel like hurricane forecasts change a lot? Hurricane forecast tracks might not mean what you think they do. Concentric circles are actually used to help form the forecast. Chief Meteorologist Bobby Deskins explains how you should really be reading these cones.

Explore an interactive global weather map, with overlays depicting real-time data on temperature, precipitation, wind, humidity, and pressure, which enable the tracking and monitoring of extreme weather events.

Every tropical storm is named from one of six predetermined lists maintained by the World Meteorological Organization.

How do hurricanes form?

Tropical cyclones, also called hurricanes and typhoons, cause catastrophic damage when they strike land. This four-minute video explores the life cycle of cyclones—how atmospheric conditions, ocean temperatures, and the Earth's rotation combine to create them, and how they are driven by winds and eventually weaken after moving over land.

Bomb cyclones can produce heavy rain, blizzard conditions, and intense winds

Known as "bombogenesis" in meteorology, these systems get their colloquial name from their rapid intensification over a 24-hour period—a phenomenon seen in some tropical cyclones. They occur most commonly along the coasts of the Northeast and Northwest US when there is a severe temperature difference between colliding air masses.

Rather than being triggered by a massive displacement of water from a geological event, meteotsunamis are caused by rapid changes in air pressure from fast-moving weather systems.

Rapid intensification is the increase in a hurricane's sustained wind speed by at least 35 miles per hour within 24 hours, which can strengthen it by up to two categories.

Why do flash floods occur?

Flash flooding can be more dangerous than traditional floods, occurring within the span of hours and exhibiting rapid currents. Here's how atmospheric conditions and geography combine to make some locations ripe for the disaster.

Tropical cyclone formation require warm water and limited vertical wind shear

Ocean temperatures above 27 degrees Celsius fuel rising, moist air, which releases energy through heat as water vapor condenses into clouds. Significant changes in wind speed with height can spread out these upflows, preventing the eventual formation of a central column known as the eye.

Storm surges, not winds, are the leading cause of hurricane-related fatalities

A storm surge is an abnormal rise in water levels generated by a storm that exceeds predicted tides. It is particularly dangerous in coastal regions, where it can generate extreme flooding well before the hurricane makes landfall.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

Nor'easters can produce thundersnow—lightning in blizzard conditions

Although thunderstorms typically require warm air to rise in updrafts and collide with heavier soft hail, which creates charge separation and eventual electrical discharge, these cyclones can replicate these conditions by churning the atmosphere through strong winds. Rarely, especially warm lakes can similarly help generate thunderstorms during the winter.

What's the difference between weather and climate?

A five-minute TedEd video exploring the differences between weather and climate – what they are, how we predict them, and what those predictions can tell us.

In the US, flash floods—rapid floods that occur within six hours of rain—kill more people than tornadoes, hurricanes, and lightning.

The cone of uncertainty predicts where a hurricane's center can potentially travel

A common misconception is that regions beyond the cone are safe, but the spread does not depict the full reach of a cyclone's wind, rain, or storm surges. The cone is not built from real-time storm data but is an average forecast error from the past five years.

In the 1940s, pilots flew into thunderstorms to learn about their formation and properties as part of the Thunderstorm Project, the first multiagency meteorological study mandated and funded by Congress.