NEXRAD
Next-Generation Radar, a network of 159 high-resolution Doppler weather radars operated by the National Weather Service. NEXRAD detects precipitation, wind patterns, and severe weather signatures up to 250 miles from each station.
More Radar & Observation Terms
MRMS
Multi-Radar Multi-Sensor, an advanced system that combines data from multiple radars, satellites, and surface observations to create a seamless, high-resolution national weather picture updated every 2 minutes.
Reflectivity
A measure of how much radar energy is reflected back by precipitation, measured in dBZ (decibels of Z). Higher values indicate heavier precipitation or larger particles. Values above 50 dBZ typically indicate heavy rain or hail.
Velocity
Doppler radar measurement of how fast precipitation is moving toward or away from the radar. Velocity data reveals wind patterns, rotation in thunderstorms, and potential tornado signatures that reflectivity alone cannot show.
Echo Tops
The maximum height at which radar detects precipitation in a storm, indicating storm intensity and updraft strength. Higher echo tops generally correlate with stronger storms. Tops exceeding 40,000 feet suggest severe weather potential.
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.
Bow Echo
A bow or crescent-shaped radar signature indicating strong straight-line winds. Bow echoes form when the center of a squall line accelerates ahead of its ends, often producing damaging winds exceeding 75 mph.
Debris Ball
A radar signature showing a concentrated area of debris lofted by a tornado. Debris balls appear as a circular area of high reflectivity collocated with rotation and confirm a tornado is on the ground causing damage.
Explore Other Terms
Tornado
A violently rotating column of air extending from a thunderstorm to the ground. Tornadoes can produce winds exceeding 300 mph and cause catastrophic damage along their path. They are rated on the Enhanced Fujita (EF) scale from EF0 to EF5.
Supercell
A severe thunderstorm characterized by a deep, persistently rotating updraft called a mesocyclone. Supercells are the most dangerous type of thunderstorm and can produce tornadoes, large hail, damaging winds, and flash flooding.
Freezing Rain
Rain that falls as liquid but freezes on contact with surfaces at or below 32°F (0°C), creating a coating of ice called glaze. Freezing rain is extremely dangerous as it can make roads impassable and cause widespread power outages from ice-coated power lines.
Sleet
Frozen raindrops that bounce when hitting the ground. Sleet forms when snowflakes partially melt falling through a warm layer, then refreeze in a cold layer near the surface. Unlike freezing rain, sleet is frozen before it hits the ground.
Barometric Pressure
The weight of the atmosphere pressing down on a given point, measured in inches of mercury (inHg) or millibars (mb). Rising pressure typically indicates improving weather, while falling pressure suggests approaching storms or precipitation.
Dew Point
The temperature at which air becomes saturated and water vapor begins to condense into liquid. A higher dew point indicates more moisture in the air. Dew points above 65°F feel humid, while above 70°F is considered oppressive.
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Learn NEXRAD in Context
These explainers and product surfaces 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
What Is a Derecho? The Inland Hurricane Explained
Learn what a derecho is, how it differs from tornadoes and hurricanes, why these long-lived windstorms are so destructive, and how to stay safe when one approaches.
Weather Education
Radar Beam Height Explained: Why Distance From Radar Matters
Learn how radar beam height affects weather detection. Understand why storms far from radar may appear weaker and how Earth's curvature impacts precipitation detection.
Helpful Tools and Hubs
Use these pages to apply the concept, compare conditions, or follow related weather workflows.
Guide
How to Read Weather Radar
Learn the basics of radar interpretation so you can tell where storms are headed and how intense they may become.
Feature
Professional Radar
Explore high-resolution radar, premium lightning, and satellite layers built for serious weather tracking.
Guide
Radar Beam Height Explained
Learn why radar can miss low-level rain, snow, and storm details depending on distance from the radar site.
Use Case
WeatherAI for Storm Chasers
See how WeatherAI supports active storm tracking with radar, severe weather context, and storm-focused workflows.
See NEXRAD in Action
WeatherAI brings weather concepts to life with professional radar, real-time alerts, and AI-powered forecasts that explain what the weather means for you.