How is the reflectivity gradient important to severe weather?
The reflectivity gradient is defined as how much the value of radar reflectivity changes over distance. If the reflectivity changes significantly over a small distance then that would be a strong reflectivity gradient. If the reflectivity changes only slightly over a significant distance then that would be a weak reflectivity gradient. Determining what is a strong gradient, weak gradient or a gradient that is in-between takes practice. With a few examples we will show how each look on radar. First we will look at a commonly used scale for reflectivity values. The scale is shown below: The green colors represent light reflectivity (light rain aloft), the yellow colors are more of a moderate reflectivity (moderate rain aloft) and the red colors represent heavy reflectivity (heavy rain and possible hail aloft). An example of a strong reflectivity gradient is a red color next to no reflectivity while an example of weak reflectivity would be a gradual transition from green to yellow colors.
