What is radar reflectivity (dBZ)?

Decibels of Z (dBZ) measures the radar energy reflected back by precipitation particles. Values from 5-20 dBZ indicate light mist or snow, 30-40 dBZ indicates moderate rain, 50-60 dBZ indicates heavy torrential downpours, and values above 60-65 dBZ frequently indicate severe hail.

How does Doppler Radial Velocity work?

Doppler velocity detects the frequency shift of reflected microwave pulses to determine whether raindrops and air masses are moving toward the radar antenna (negative/inbound, depicted in green/blue) or away from the radar antenna (positive/outbound, depicted in red/orange). A tight red-green adjacent couplet often signifies rotation or a tornado vortex signature (TVS).

How is rainfall rate calculated from dBZ?

Rainfall rate is calculated using the empirical Marshall-Palmer Z-R relationship: Z = 200 × R^1.6 (where Z is reflectivity factor in mm^6/m^3 and R is rainfall rate in mm/hr). In dBZ, Z = 10^(dBZ / 10).

Can this radar tool run offline?

Yes. The entire radar rendering engine, mathematical wave propagation models, Doppler velocity solvers, and animation loop state machines execute 100% client-side inside your browser canvas with zero external server dependencies.

What is radar reflectivity (dBZ)?

Decibels of Z (dBZ) measures the radar energy reflected back by precipitation particles. Values from 5-20 dBZ indicate light mist or snow, 30-40 dBZ indicates moderate rain, 50-60 dBZ indicates heavy torrential downpours, and values above 60-65 dBZ frequently indicate severe hail.

How does Doppler Radial Velocity work?

Doppler velocity detects the frequency shift of reflected microwave pulses to determine whether raindrops and air masses are moving toward the radar antenna (negative/inbound, depicted in green/blue) or away from the radar antenna (positive/outbound, depicted in red/orange). A tight red-green adjacent couplet often signifies rotation or a tornado vortex signature (TVS).

How is rainfall rate calculated from dBZ?

Rainfall rate is calculated using the empirical Marshall-Palmer Z-R relationship: Z = 200 × R^1.6 (where Z is reflectivity factor in mm^6/m^3 and R is rainfall rate in mm/hr). In dBZ, Z = 10^(dBZ / 10).

Can this radar tool run offline?

Yes. The entire radar rendering engine, mathematical wave propagation models, Doppler velocity solvers, and animation loop state machines execute 100% client-side inside your browser canvas with zero external server dependencies.

Live Weather Radar & Doppler Reflectivity

Free client-side weather radar viewer and Doppler simulator. Analyse composite reflectivity dBZ, radial velocity couplets, echo tops, and rainfall rates.

Storm Scenario Presets:

BASE REFLECTIVITY (dBZ) RANGE: 125 NM 14:50 UTC (SCAN +0m)

Reflectivity Intensity (dBZ) Light • Moderate • Heavy • Extreme Hail

5 15 25 35 45 55 65 75+

-45m -30m -15m NOW

Speed:

🔍 Radar Product

Composite Reflectivity (dBZ) Precipitation intensity & storm cores Doppler Radial Velocity Inbound vs outbound wind vectors Echo Tops (kft AGL) Cloud vertical development & anvil height Precipitation Rate (in/hr) Instantaneous surface accumulation

⚙ Radar Overlays

Range Rings (25, 50, 75, 100, 125 NM) Geographic City Markers & Airports County Boundaries & High Altitude Grid Compass Azimuth Degree Scale Radar Beam Interpolation (Smooth)

🖇 Storm Cell Inspector

Click anywhere on the radar scope to probe atmospheric parameters at that coordinates.

Target Coordinates: Click scope to inspect

Reflectivity (dBZ): --

Estimated Rain Rate: --

Radial Wind Velocity: --

Echo Top Altitude: --

Severe Weather Threat: --

How Weather Radar Works

Weather surveillance radars (such as the National Weather Service's WSR-88D NEXRAD network) transmit concentrated directional pulses of electromagnetic microwave radiation in the S-band (2.7 to 3.0 GHz) or C-band (5.6 GHz). As these radio waves encounter airborne precipitation particles (water droplets, ice crystals, graupel, and hail), a minute fraction of the energy scatters back toward the parabolic antenna.

By measuring the precise elapsed transit time (yielding distance), antenna azimuth angle (yielding compass bearing), and returned power intensity, the radar processor reconstructs a high-resolution 3D volumetric map of the storm atmosphere.

Understanding Doppler Radial Velocity & Rotation

While standard reflectivity reveals where raindrops exist, Doppler Radial Velocity measures how rapidly those hydrometeors are traveling toward or away from the radar radar dish:

Green / Blue (Inbound): Air mass moving inward toward the radar antenna.
Red / Orange (Outbound): Air mass moving outward away from the radar antenna.
Velocity Couplets: When a tight bright green pocket directly abuts a bright red pocket, powerful cyclonic rotation is occurring within the mesocyclone. This velocity signature is the primary indicator used by meteorologists to issue Tornado Warnings before a funnel touches down.

Marshall-Palmer Z-R Rainfall Relationship

To convert measured decibels of reflectivity into surface rainfall accumulation rates in inches per hour, radar systems apply empirical Z-R power-law formulations. The foundational equation is the Marshall-Palmer formula:

Z = 200 × R^1.6

Where Z is the radar reflectivity factor (mm⁶/m³) related to dBZ by dBZ = 10 × log₁₀(Z), and R is instantaneous rainfall rate in mm/hour.

Frequently Asked Questions

What is the "Cone of Silence"?: Ground radar antennas have a maximum physical elevation tilt (typically around 19.5 to 20 degrees). The inverted conical volume of sky directly above the radar site cannot be scanned by the beam, creating an unmonitored zone known as the cone of silence.
Why do severe storms show purple or white colors on radar?: Precipitation reflectivity above 60 to 65 dBZ exceeds the physical maximum reflection possible from liquid water droplets alone (droplets break apart if too large). Reflectivity values in the 65-75+ dBZ range indicate large, dense hail stones that act like retro-reflecting mirrors.
What is the difference between Base Reflectivity and Composite Reflectivity?: Base Reflectivity displays returned echoes from only a single elevation angle scan (typically the lowest 0.5° tilt). Composite Reflectivity takes the highest recorded reflectivity value across all scanned tilt elevations for each column, displaying the maximum intensity of the storm regardless of altitude.

About this tool

How to use it

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Why it matters

Modern Doppler weather radar is crucial for identifying severe thunderstorms, tornado vortex signatures (velocity couplets), flash flooding rain rates, and hail cores. This client-side radar viewer provides an instant educational and analysis workbench that demonstrates radar physics, Marshall-Palmer Z-R rainfall equations, and beam propagation without heavyweight video ads, telemetry trackers, or external network dependencies.

When to use it

Use this simulator and viewer when studying meteorology, practicing radar interpretation for FAA flight exams, analyzing storm morphology (hook echoes, bow echoes, outflow boundaries), or testing storm-tracking logic in browser applications.