NEXRAD stands for Next Generation Weather Radar — the U.S. national network of 160 WSR-88D Doppler weather radars operated by the National Weather Service, the Department of Defense, and the FAA across the United States, Caribbean, and select overseas military bases. Every NEXRAD site uses the same WSR-88D hardware (Weather Surveillance Radar — 1988 — Doppler).

What is NEXRAD radar used for?

NEXRAD detects precipitation intensity (reflectivity), motion (Doppler velocity), and — since the 2013 dual-polarization upgrade — distinguishes rain from hail from tornado debris. It is the primary data source for severe-weather warnings, flash-flood guidance, winter-storm forecasting, and aviation routing. Every U.S. weather app, broadcast TV station, and emergency manager consumes NEXRAD data.

How many NEXRAD radars are there?

160 operational WSR-88D sites: 122 operated by the NWS, 12 by the FAA at high-traffic airports, and 26 by the DoD on military bases (including a few overseas sites in Korea, Japan, Guam, Hawaii, Puerto Rico, and elsewhere). The network gives near-complete coverage of the lower 48 states above 10,000 feet, with known gaps below 6,000 feet in the Intermountain West, the northern Plains, and parts of the Gulf Coast.

What is the difference between NEXRAD Level 2 and Level 3 data?

Level 2 is the raw radar product — reflectivity, velocity, and spectrum width at every elevation angle and every pulse, ~5 GB per site per day. Level 3 is the pre-processed products derived from Level 2 — base reflectivity at each tilt, the composite, storm-relative velocity, hydrometeor classification, vertically-integrated liquid, and so on. Most consumer apps use Level 3; serious chasers and spotters use Level 2 for the highest resolution and access to the full velocity field.

What does dual-polarization mean for NEXRAD?

Dual-polarization (rolled out 2010-2013) means each radar transmits both horizontally and vertically polarized pulses, allowing the radar to distinguish particle shape and orientation. The headline benefit is the Tornado Debris Signature — a specific low-correlation-coefficient hole inside a velocity couplet confirms a tornado is actively lofting debris. Dual-pol also distinguishes rain from hail from snow and from biological scatterers (birds, bats, insects).

What are NEXRAD's limitations?

Two physical limitations matter most. First, beam height grows with range — at 100 miles, the lowest tilt is already ~7,000 feet above ground, so the radar misses low-level snow, light rain, and low-topped supercells. Second, beam resolution drops with range — at 200 miles each pixel covers several square miles. There is also a "cone of silence" near each radar (within ~5 miles) where the radar cannot see at low altitudes because of the minimum scan angle.

Yes. NEXRAD data is public domain. NOAA distributes Level 2 in real time through the AWS NEXRAD on Cloud / Big Data Project (free egress from S3). Level 3 products are available from NWS gateways. Consumer apps like RadarScope add a service-layer fee for the convenience of fast access, dual-pol decoding, and a polished interface — but the underlying data is yours for the asking.

When was NEXRAD built?

Deployment began in 1988 and reached operational status across the network by 1997, replacing the WSR-57 and WSR-74 analog radars. The dual-polarization upgrade rolled out 2010-2013. The Service Life Extension Program (SLEP) keeps the WSR-88D hardware operational through approximately 2040; NOAA is currently funding research into a phased-array replacement that could scan 5-10× faster, targeted for the 2040s.

What is the difference between NEXRAD and a composite radar?

A NEXRAD radar is a single WSR-88D site producing data from one location. A composite radar (what most consumer apps show) is a national mosaic that combines all 160 NEXRAD sites into one picture by taking the highest reflectivity at each pixel. The composite is great for situational awareness but loses access to velocity, dual-pol products, and per-site scan timing. For active spotting, use a single-site Level 2 viewer rather than the composite.

What is NEXRAD? — How the U.S. Doppler Weather Radar Network Works

What is NEXRAD? — How the U.S. Doppler Weather Radar Network WorksNEXRAD (Next Generation Weather Radar) is the network of 160 WSR-88D Doppler radars operated by the NWS, FAA, and DoD across the U.S. How each site scans, what reflectivity and velocity products mean, dual-polarization, Level 2 vs Level 3 data, and the network's coverage gaps.NEXRAD stands for Next Generation Weather Radar — the U.S. national network of 160 Doppler weather radars operated by the National Weather Service, the Department of Defense, and the FAA. Every NEXRAD site is a WSR-88D (Weather Surveillance Radar — 1988 — Doppler), the specific hardware model that makes up the network.NEXRAD is the primary data source behind every severe-weather warning, every TV-station radar display, and every consumer weather app in the United States.How a WSR-88D worksEach radar rotates a parabolic antenna 360° at multiple elevation angles ("scan strategy"), emitting 10 cm S-band radio pulses and listening for the reflected energy from precipitation. The time delay gives range; the Doppler shift gives radial wind velocity (motion toward or away from the radar); the returned power gives reflectivity (precipitation intensity). A full volume scan completes every 4–10 minutes depending on weather mode — faster in severe weather.Key products

Reflectivity: How much energy bounced back. Color-coded on every radar display — green for light rain through red and magenta for hail.

Velocity: How fast precipitation is moving toward or away from the radar (Doppler shift). The single most important product for spotting rotation and gust fronts.

Dual-polarization: 2013 upgrade. Each radar now transmits both horizontal and vertical pulses, letting the radar distinguish particle shape and orientation.

Tornado Debris Signature (TDS): A specific dual-pol signature (low correlation coefficient inside a velocity couplet) that indicates a tornado is actively lofting debris. Real-time confirmation of tornado damage.

Coverage and limitationsThe 160 sites give near-complete coverage of the lower 48 states above 10,000 feet, with significant gaps below 6,000 feet in the Intermountain West, the northern Plains, and the Gulf Coast.

Beam height vs. range: The radar beam curves upward with Earth's curvature. At 100 miles range, the lowest beam is already ~7,000 feet above ground — too high to see surface-level precipitation, snow accumulation, or low-topped supercells. The "cone of silence" right above each radar (closer than ~5 miles) also has poor low-altitude coverage.

Resolution drops with distance: The beam spreads as it travels. At 200 miles, each pixel covers a few square miles of atmosphere — fine for "there's a storm somewhere out there", useless for spotting a tornado debris ball.

These limitations are why spotters cross-reference multiple radars when they can, and why the closest single-site radar is almost always better than the national mosaic for active severe weather.NEXRAD vs. composite radarA composite radar (what BloomWX and most consumer apps show) is a national mosaic that combines all 160 NEXRAD sites into one picture, taking the highest reflectivity at each pixel. Good for situational awareness; weak for severe-weather analysis because you lose access to velocity products, dual-pol signatures, and per-site scan timing.For active spotting work, use a single-site Level 2 viewer like RadarScope — it surfaces the raw WSR-88D products instead of a precipitation-only mosaic. See How to Read NEXRAD Radar for the colors, polygons, and storm-report pins on the BloomWX composite.Data products and accessNEXRAD data is public domain. NOAA distributes it in two formats:

Level 2: Raw radar data — reflectivity, velocity, spectrum width at every elevation, every pulse. ~5 GB/site/day. Streamed from NOAA Big Data Project (AWS S3) for free.

Level 3: Pre-processed products derived from Level 2 — base reflectivity at each tilt, composite, storm-relative velocity, hydrometeor classification. Smaller, easier to render.

Most weather apps consume Level 3. RadarScope and serious chasers decode Level 2 directly for the latest scan and full velocity access.HistoryNEXRAD deployment began in 1988 and reached operational status across the network by 1997, replacing the WSR-57 and WSR-74 analog radars that preceded it. The dual-polarization upgrade rolled out 2010–2013, adding the ability to distinguish rain from hail from tornado debris. The Service Life Extension Program (SLEP) is currently keeping the WSR-88D hardware operational through approximately 2040; NOAA is funding research into a phased-array replacement that could scan 5–10× faster and is targeted for the 2040s.NEXRAD is one of the highest-value public datasets the U.S. government produces. Every weather app, every TV station, every storm chaser, every emergency manager — all running off the same 160 radars.

Frequently asked questions

What is NEXRAD?: NEXRAD stands for Next Generation Weather Radar — the U.S. national network of 160 WSR-88D Doppler weather radars operated by the National Weather Service, the Department of Defense, and the FAA across the United States, Caribbean, and select overseas military bases. Every NEXRAD site uses the same WSR-88D hardware (Weather Surveillance Radar — 1988 — Doppler).
What is NEXRAD radar used for?: NEXRAD detects precipitation intensity (reflectivity), motion (Doppler velocity), and — since the 2013 dual-polarization upgrade — distinguishes rain from hail from tornado debris. It is the primary data source for severe-weather warnings, flash-flood guidance, winter-storm forecasting, and aviation routing. Every U.S. weather app, broadcast TV station, and emergency manager consumes NEXRAD data.
How many NEXRAD radars are there?: 160 operational WSR-88D sites: 122 operated by the NWS, 12 by the FAA at high-traffic airports, and 26 by the DoD on military bases (including a few overseas sites in Korea, Japan, Guam, Hawaii, Puerto Rico, and elsewhere). The network gives near-complete coverage of the lower 48 states above 10,000 feet, with known gaps below 6,000 feet in the Intermountain West, the northern Plains, and parts of the Gulf Coast.
What is the difference between NEXRAD Level 2 and Level 3 data?: Level 2 is the raw radar product — reflectivity, velocity, and spectrum width at every elevation angle and every pulse, ~5 GB per site per day. Level 3 is the pre-processed products derived from Level 2 — base reflectivity at each tilt, the composite, storm-relative velocity, hydrometeor classification, vertically-integrated liquid, and so on. Most consumer apps use Level 3; serious chasers and spotters use Level 2 for the highest resolution and access to the full velocity field.
What does dual-polarization mean for NEXRAD?: Dual-polarization (rolled out 2010-2013) means each radar transmits both horizontally and vertically polarized pulses, allowing the radar to distinguish particle shape and orientation. The headline benefit is the Tornado Debris Signature — a specific low-correlation-coefficient hole inside a velocity couplet confirms a tornado is actively lofting debris. Dual-pol also distinguishes rain from hail from snow and from biological scatterers (birds, bats, insects).
What are NEXRAD's limitations?: Two physical limitations matter most. First, beam height grows with range — at 100 miles, the lowest tilt is already ~7,000 feet above ground, so the radar misses low-level snow, light rain, and low-topped supercells. Second, beam resolution drops with range — at 200 miles each pixel covers several square miles. There is also a "cone of silence" near each radar (within ~5 miles) where the radar cannot see at low altitudes because of the minimum scan angle.
Is NEXRAD data free?: Yes. NEXRAD data is public domain. NOAA distributes Level 2 in real time through the AWS NEXRAD on Cloud / Big Data Project (free egress from S3). Level 3 products are available from NWS gateways. Consumer apps like RadarScope add a service-layer fee for the convenience of fast access, dual-pol decoding, and a polished interface — but the underlying data is yours for the asking.
When was NEXRAD built?: Deployment began in 1988 and reached operational status across the network by 1997, replacing the WSR-57 and WSR-74 analog radars. The dual-polarization upgrade rolled out 2010-2013. The Service Life Extension Program (SLEP) keeps the WSR-88D hardware operational through approximately 2040; NOAA is currently funding research into a phased-array replacement that could scan 5-10× faster, targeted for the 2040s.
What is the difference between NEXRAD and a composite radar?: A NEXRAD radar is a single WSR-88D site producing data from one location. A composite radar (what most consumer apps show) is a national mosaic that combines all 160 NEXRAD sites into one picture by taking the highest reflectivity at each pixel. The composite is great for situational awareness but loses access to velocity, dual-pol products, and per-site scan timing. For active spotting, use a single-site Level 2 viewer rather than the composite.

Part of the BloomWX learn library — beginner-friendly explainers covering every surface of the BloomWX weather dashboard. Open BloomWX to see live data for any U.S. county.