Radar Sounders
NEXRAD (Next Generation Radar) is the next generation of weather radar technology that is operational at 158 sites throughout the United States and at selected overseas locations. Meteorologists can now warn the public to take shelter with more notice than any previous radar. The maximum range of the NEXRAD radar is 250 nautical miles. The NEXRAD network provides significant improvements in severe weather and flash flood warnings, air traffic safety, flow control for air traffic, resource protection at military bases, and management of water, agriculture, forest, and snow removal. The NEXRAD is capable of operating in three different modes, Precipitation mode, Clean air Mode, and Severe weather mode. The radar is placed in precipitation mode when a significant amount of precipitation is detected. It completes nine full scans at different elevation angles between 0.5 and 19.5 degrees and is updated every six minutes. The NEXRAD offers much more resolution in precip levels. Old radars only had six precip levels, the NEXRAD has fifteen levels, which enables it to give more accurate descriptions on the intensity of precipitation. When the NEXRAD is placed in clean air mode the radar becomes more sensitive and is updated every ten minutes after completing five full scans at different elevation angles between 0.5 and 4.5 degrees. It is useful to measure those winds in "clear air" from very weak returns on dust, insect, smoke, etc. It is also capable of depicting snow very well, a feature that old radars had trouble with. The Severe weather mode is activated when a severe weather pattern is detected. The radar then completes fourteen scans between 0.5 and 19.5 degrees in five minutes. The NEXRAD calculates both the speed and direction of motion of severe storms. By providing information on wind patterns within developing storms, the NEXRAD identifies conditions leading to tornadoes and can subsequently give accurate data on the direction and speed of formed tornadoes. Additional information available at "http://www.roc.noaa.gov/" [Summary provided by NOAA Radar Operations Center]
NEXRAD