How to Read Reflectivity Maps

The National Weather Service, private weather services and television news stations use Doppler radar to detect storm locations and intensity. Doppler radar measures wind speed and direction, as well as precipitation accumulation. The radar generates separate images for precipitation and wind. The color image showing precipitation is called a reflectivity map. A base reflectivity map shows where precipitation hits the ground, while a composite reflectivity maps shows precipitation at the four different tilts of the radar or from the atmosphere to the ground. The various intensities show as different colors. Meteorologists then overlay the radar image with a local or state map.

Instructions

• 1

  Find your location on the reflectivity map. The major cities and towns are normally marked, as are the county and state borders.

• 2

  Determine the color of precipitation at or near your location. There is no standard color set used by all weather sources. It depends on the mapmaker and the range of differences between precipitation amounts.

• 3

  Reference the map key to find the level of precipitation associated with the color at your location. The map key is normally on the right side or bottom of the map.