Radar vs. Precipitation graph

Hi all.

Sorry if this is a simple question or is answered in the FAQ. I didn’t see anything when I checked.

Does anyone know why the composite radar will show rain on the map while the precipitation graph remains bare? I know composite is at 1km and 4km with HRR and NAM data, but I should expect either HRR or NAM to show precipitation on the graph right? I checked with 1km and 4km maps and both are showing rain, but neither HRR or NAM graphs show any.



@Matt Hello and Welcome to the Forum and Thank You for Using Flowx. could be a glitch try closing app then reopen if no change try cleaning app cache also can try a refresh or forced refresh also it could be not a lot of rain is expected try adding precipitation to the area where the clock is to see if it shows a measurement


Hi @Matt and welcome to the forum!

It could be a glitch as @BrianLY-38 said.

Another possible explanation is that “radar” is (measured or predicted) levels of reflection, i.e. measurements of amounts of particles up in the atmosphere, where as “precipitation” per definition is the amount that actually hits the ground.

I’m not sure if this is the case in your example, but it is sometimes possible that a radar will give a signal from reflecting on droplets of water that is falling from a cloud high up enough, in combination with temperature, updrafts, humidity and so on, that the drops will have evaporated completely before they ever reach the ground, and hence no actual precipitation.

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The graph shows precipitation data, not the radar data. This is just the way the graph is configured.

So the question is really “Why is precipitation and radar so different?” I don’t really know much about radar except it just measure reflectivity. It has different units. There was a good post on the forum about the difference between 1km radar, 4km radar and composite radar. This post might answer your questions.

Another possibility is that the precipitation has a higher minimum cut-off compared to radar.


Probably this one:

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I think it was this one. I don’t know how to quote another post properly. Feel free to report this @Ohan, and I’ll delete this post.