

Doppler radars that get out of calibration.However, a worse case is when subrefraction is occurring and the beam is overshooting the most intense regions of storms (indicating weaker storms than what are actually occurring). When ducting occurs, the radar beam is refracted into the ground (indicating stronger storms than what are actually occurring). Atmospheric conditions such a ducting."Dry hail" is a very poor reflector of energy and can lead to an underestimate of a storm's intensity. Hail that is totally frozen (without a thin layer of water in the surface).Severe weather may be occurring with values less (or greater) than 60 to 65 dBZ due to. However, a value of 60 to 65 dBZ does not mean that severe weather is occurring at that location. The values of 60 to 65 dBZ is about the level where 1" (2.5 cm) diameter hail can occur. Value of 20 dBZ is typically the point at which light rain begins. As dBZ values increase so does the intensity of the rainfall. The color scale is located at the lower right of each image. The colors represent the strength of returned energy to the radar expressed in values of decibels (dBZ).

The radar is located in the center of the image. This image (right) (above) is a sample base reflectivity image from the Doppler radar in Frederick, OK. A Base Reflectivity image indicating precipitation.
