Colors on the weather radar?

Question

I know a bad thunderstorm is coming when the red color starts popping up on my weather radar. There are purple and white colors above it on the scale however. I've never actually seen these colors manifest within storms on the radar. Would these colors indicate some freakishly high cloud tops? What type of evil weather should I expect if I ever see these funky upper-end colors?

Answer 1

Purple and White "usually" indicate a base reflectivity of dense and highly elevated moisture content in the atmosphere. This means that yes, there is heavy rain falling if it's relatively warm at the surface. If it's say, around 32 degrees at the surface, there's heavy snow falling, probably a white-out or a blizzard. This is also a good indication that if it's warm at the surface, there is large hail falling as well.

Answer 2

Those purple and white colors are one of two things.

1) You could have seen the scales for snow and ice. Some radars display those too.

2) You viewed a radar that displays a wider range of rainfall intensities. Purples and whites would generally refer to something tropical in origin, such as a tropical storm or hurricane.

Doppler radars base intensity values off of reflectivity. If there are more raindrops, then there is more reflectivity of radar waves, and therefore is a sign of greater intensity rainfall. That would signify a more intense thunderstorm.