WRAL WeatherCenter Blog

Was looking at the radar and see some black places and now some white areas near New Bern. What do the blacks & whites signify?

Posted April 27, 2008

MIKE MOSS SAYS:        Edwin,    I'm assuming you mean the colors displayed on the radar that tend to run from light blue to green to yeallow, red, purple and so on as reflectivities increase. In this case, you saw some colors at the core of precipitation echoes that went beyond those levels to black or white. This simply indicates higher reflectivities (a measure of the amount of radar energy being returned to the radar by scattereing from the precipitation particles in the system being swept by the beam) than in surrounding areas. This can indicate very high rainfall rates due to a combination of especially large raindrops and/or a very large number of drops, or in many cases it may represent a hail shaft, because moderate to large-size hailstones are very reflective of radar energy, especially if they are coated with liquid water. Seeing the purple, black and white coded reflectivity areas at relatively low altitudes is often a good indicator that hail is reaching the ground beneath that storm. If not, then some very heavy rainfall is occuring.


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