What Does The Purple Color (“RF”) Indicate?
Radial Wind Velocity data may be missing in places on any given display if there are no scatterers in the atmosphere to return the radar’s signal from which the velocity data is derived. There needs to be either precipitation, cloud cover, smoke, sea spray or some particle in the atmosphere large enough to reflect the radar’s signal back to the radar in order to get wind speed data. This is why when precipitation is scattered across an area, velocity data will only appear in the areas where the precipitation is located and will be missing in other areas. For this reason, it is very useful to compare what is seen on a given Wind Velocity display with what is seen on the Base Reflectivity display of the same tilt angle. RF, the purple color in the key, stands for Range Folding or bad data. In these areas, the radar detected something but was unable to detect the true wind speed or was unable to determine the proper location of the wind speed that was detected. Rather than display misinfo
