NEXRAD, or next-generation weather radar, is one of the most recent technological breakthroughs for weather forecasting. NEXRAD relies on the Doppler Effect to calculate the position and the velocity of precipitation. The spherical NEXRAD radar tower emits radar waves 360° around and calculates the frequency shift of the reflected radar waves off rain, sleet, and snow. The NEXRAD computers then translate the information and represent the possible weather problems on a color-coded map for analysis. The maps are readily available in real time over the Web.

The goal and main function of NEXRAD precision radar is to save American money and lives by predicting threatening weather problems and warning the public before tragedy strikes. Meteorologists estimate that this new tool for weather forecasting has saved millions of dollars and many lives through its early warning systems. One of the most impressive advancements has been in pinpointing tornadoes and hurricanes more accurately than what was possible before NEXRAD.

Each NEXRAD station scans a radius of 125 miles with excellent accuracy, and less accurately up to 200 miles. A new system, developed since 1994, is Terminal Doppler Weather Radar, or TDWR. This system, installed at 45 airports, uses radar waves with 5-centimeter wavelength rather than the 10 centimeters (3.9 inches) used in standard weather radar. As a result it can resolve objects with twice as much detail, permitting it to detect wind shear and microbursts. Its range, however, is half that of NEXRAD and it can’t see through heavy rain. Radar images are available to the public at www.radar.weather.gov.