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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

All hurricanes have a central eye, where no extreme weather occurs, surrounded by intense winds and thunderstorms.

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.

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.

Due to a local microclimate, a thunderstorm nicknamed Hector the Convector appears almost every day from September to March at around 3 pm off the northern coast of Australia.

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.

Atmospheric processes amplify the strength of storms by coalescing clouds

Research has shown that turbulent mixing of air at the edges of clouds and other small-scale thermal activity beneath them help clouds group together, intensifying short bursts of rainfall, especially in tropical regions. Simulations reveal this produces more powerful storms than predicted by older models, though they may occur less frequently.

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

During a tornado watch, atmospheric conditions favor the development of a tornado, and residents in an area should be prepared to seek refuge. A tornado warning is issued if a tornado has been detected, while a tornado emergency indicates a violent tornado has touched down in the area, with severe threats to human life and property expected.

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.

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.

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.

Watch how scientists learn about hurricanes by flying into them

A specialized fleet of Air Force planes is built to fly into hurricanes and gather critical data from inside the storm. Beyond radar and microwave sensors, the planes are equipped with dropsondes—small instruments dropped into storms to measure pressure, temperature, and wind.

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.

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.

Hurricanes spin due to differences in air and ground speed as they move across Earth

The movement of an object across latitudes causes it to take a curved trajectory because its speed no longer matches that of the ground beneath it. This phenomenon, called the Coriolis effect, explains why hurricanes spin counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.

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.

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 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.

Hurricanes can grow by replacing their eyewall

A second outer eyewall can form around the primary eyewall surrounding a hurricane's eye. During an eyewall replacement cycle, the outer wall can weaken, collapse, and replace the inner wall, temporarily weakening the storm before it strengthens and grows.

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.

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.

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.

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.

Hurricanes, which rely on air consistently spinning in the same direction, cannot cross the equator because air curves in opposite directions north and south of it.

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.

Some earthquakes can produce smaller tremors called boomerang earthquakes, which travel in the opposite direction and ripple back to the original earthquake's source.

Horsehead-shaped features seen on the sun and the clouds of Earth and Jupiter are examples of Kelvin-Helmholtz instabilities, where a faster-moving fluid rolls atop a slower-moving fluid.

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.

A sound's pitch will seem to change if the listener or the source moves toward or away from the other because motion changes the time it takes each successive sound wave to reach the listener.

Thunder occurs when fast-flowing electricity heats and pressurizes air, causing it to expand and produce a shockwave at each point along the bolt at multiple frequencies.

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.

Lightning storms are more common in coastal and tropical regions

Water-abundant areas that receive increased solar radiation, such as those near the equator, experience increased rates of evaporation, which produce tall clouds as moisture rises, cools, and condenses. Mountain ranges can also steer air to higher altitudes, creating collisions between atmospheric particles that generate charge imbalances—the precursors to lightning.

Watch a simulated flight through Jupiter's Great Red Spot

Since its discovery over 350 years ago, the anticyclonic storm—with a high-pressure center and flows opposite to the low-pressure system underneath it—has fascinated astronomers due to its size, which is larger than Earth's, and its prominent features, including winds that surpass 250 miles per hour.

Tropical cyclones are called hurricanes, typhoons, and cyclones around the world

Tropical cyclones are named differently based on their region of origin due to historical traditions and cultural importance. These storms are called hurricanes in the Atlantic and northeast Pacific oceans, cyclones in the southwest Pacific and Indian oceans, and typhoons in the northwest Pacific Ocean.

Check out hurricane history where you live

The NOAA's historical hurricane tracker lets you explore over 150 years of data to see where hurricanes traveled and made landfall. The tool lets you search by location, name, or year; create maps and tables; and read NOAA storm reports.

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.

The Great Red Spot, Jupiter's largest storm, has existed for nearly 200 years

Despite decreasing in size, the anticyclone remains larger than Earth, rotating with winds up to 933 km/h. Its longevity may be because it is trapped between two opposite-flowing jet streams, which act like two conveyor belts.

Dust from the Sahel and Saharan regions makes northwest Africa a hurricane nursery

NASA’s Convective Processes Experiment—Cabo Verde studied the early stages of hurricane formation, identifying how dust interacts with clouds over the ocean to produce the rainy disturbances that become tropical cyclones.

How jet streams, which reside in the troposphere, shape and confine pockets of atmospheric air

These fast-flowing ribbons of air are hundreds of kilometers wide and typically travel from west to east due to Earth's rotation, with the polar front and subtropical jets serving as major drivers of global circulation. Warmer air near the equator pushes the polar front jets toward the poles, which can buckle and deform them as they contain frigid polar vortex systems.

Track lightning strikes around the world

The Blitzortung platform triangulates the positions of this phenomenon from stations that detect atmospheric interference in low-frequency signals that are characteristic of lightning strikes. A network of nearly 2,000 stations transmits the required data to a central server, where its software performs these calculations and generates the subsequent visualization.