Supercell
A supercell is a thunderstorm with a deep, persistently rotating updraft called a mesocyclone. Supercells are the most dangerous type of thunderstorm: they produce nearly all significant tornadoes in the United States and most hail larger than golf balls, along with damaging winds and flash flooding.
Why It Matters
An ordinary thunderstorm has one updraft and one downdraft and a short life. A supercell is a single cell that can persist for many hours, with updrafts that can exceed 100 mph and outflow winds just as strong.
Supercells form when the wind changes direction and speed with height, for example southerly winds at the surface and westerly winds at about 15,000 feet. That wind shear is what sets the updraft rotating.
The Three Types of Supercell
| Type | Precipitation | What to expect |
|---|---|---|
| Classic | Heavy precipitation falls next to the updraft | Large hail is likely, and strong, long-lived tornadoes are possible. Most supercells are this type. |
| Low precipitation (LP) | Sparse, often transparent | Large hail that is hard to see, and no hook echo on radar. |
| High precipitation (HP) | Nearly surrounds the updraft | Tornadoes may be wrapped in rain, with extremely heavy rain and flash flooding likely. |
Frequently Asked Questions
Do all supercells produce tornadoes?
No. Supercells produce the most destructive and deadly tornadoes, but many supercells never produce one. A supercell without a tornado can still bring large hail, damaging winds, and flash flooding.
How is a supercell different from an ordinary thunderstorm?
Rotation and lifespan. An ordinary single-cell storm has one updraft and one downdraft and dies out quickly. A supercell has a rotating updraft, called a mesocyclone, and can last for many hours while producing large hail, damaging winds, and tornadoes.
What does a supercell look like on radar?
A classic supercell often shows a hook echo, a hook-shaped extension on the storm's right rear side where precipitation wraps around the mesocyclone. Velocity data shows the rotation itself. Low precipitation supercells may show no hook at all.
Related Terms
Mesocyclone
A rotating vortex of air within a supercell thunderstorm, typically 2-6 miles in diameter. Mesocyclones are detected by Doppler radar and indicate the potential for tornado development.
Tornado
A tornado is a violently rotating column of air in contact with the ground, extending from a thunderstorm. Tornadoes are rated from EF0 to EF5 on the Enhanced Fujita scale by the damage they cause. Most last less than 10 minutes, but the strongest can stay on the ground for more than an hour.
Hook Echo
A distinctive hook-shaped radar signature on the right rear of a supercell thunderstorm, indicating rotation and high tornado probability. Hook echoes form as precipitation wraps around the mesocyclone.
Wall Cloud
An isolated lowering of a rain-free cloud base, typically found on the south or southwest side of a supercell. Wall clouds often rotate and may produce a funnel cloud or tornado. They usually precede tornado formation by 10-20 minutes.
Wind Shear
A change in wind speed or direction over a short distance, either horizontally or vertically. Strong wind shear is essential for supercell and tornado development but is also a significant hazard to aircraft during takeoff and landing.
Hail
Balls or irregular lumps of ice produced in severe thunderstorms. Hailstones form when updrafts carry raindrops into extremely cold areas of the atmosphere where they freeze. Repeated cycles through the updraft can create hailstones larger than softballs.
CAPE
CAPE (Convective Available Potential Energy) is the amount of energy a rising parcel of air can draw from the atmosphere, measured in joules per kilogram (J/kg). The higher the CAPE, the faster a storm's updraft can rise, and the stronger thunderstorms can become once something sets them off.
Supercell: Guides and Explainers
These explainers connect this definition to real-world forecasting and decision-making.
Weather Education
How Tornadoes Form: Types, EF Scale, and Safety
Learn how tornadoes form from supercell thunderstorms, the Enhanced Fujita scale, types of tornadoes, and critical safety steps to protect yourself.
Weather Education
Moisture, Instability, Lift, and Wind Shear: The 4 Storm Ingredients
Learn the four thunderstorm ingredients meteorologists look for: moisture, instability, lift, and wind shear, plus how they combine to create severe storms.
Guides
SPC Outlooks Explained: Marginal, Slight, Enhanced, Moderate, High Risk
Learn how to read Storm Prediction Center outlooks, what SPC risk levels mean, and how tornado, hail, wind, moisture, instability, lift, and shear shape severe weather forecasts.
Helpful Tools and Hubs
Use these pages to apply the concept, compare conditions, or follow related weather workflows.
Seasonal Hub
Tornado Season Guide
Peak tornado timing by region, safety planning, and how warnings work.
Feature
Severe Weather
Follow outlooks, watches, warnings, and storm signals in one severe-weather workflow.
Seasonal Hub
Severe Weather Season Guide
A seasonal hub for tornadoes, hail, damaging winds, and storm-prep reading.
Guide
What Causes Thunder and Lightning?
How lightning forms through charge separation, what causes thunder, and how to stay safe.
Sources
Explore Other Terms
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Thundersnow
A rare phenomenon where thunder and lightning occur during a snowstorm. Thundersnow typically happens in intense winter storms and is often associated with heavy snowfall rates of 2-4 inches per hour.
Wet-Bulb Temperature
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Watch vs. Warning
A watch means the risk of hazardous weather has risen but its timing, location, or occurrence is still uncertain: be prepared. A warning means hazardous weather is occurring, imminent, or likely and threatens life or property: take action now. An advisory covers events that are occurring or likely but less serious than a warning.
IFR
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