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dreamlander

Different radars show different results

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Hi, I know next to nothing about weather, but I am trying to learn.

I downloaded Pylk3 on my phone based on a bunch of recommendations. I have done enough reading to understand reflectivity and velocity, and how to read them.

I am really having trouble understanding the radar from location to location. Sorry I might not be using correct terms here, but try to follow. If I am viewing the radar from one city it shows no precipitation. Then I switch to another city that is 100 mi away from the first location, and it show a big stretch of precipitation in an area that is also covered by for first city's radar. What the heck is going on here? I live close to the same distance from both cities. Yet one radar show precip overhead and the other doesn't. Help me understand please.

Also if you could point me to any good radar learning reading or videos for a beginner I would appreciate it. My main interest is following and predicting storms.

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It sounds like, since you point out that you are roughly equidistant between the two radars, that you know that radars will scan different parts of the atmosphere depending on how far away they are. If not, here's a link that provides some insight: http://forecast.weather.gov/jetstream/doppler/baserefl.htm

One thing I can think of is, maybe the two radars were using different scan modes at the time (known as Volume Coverage Patterns, or VCPs). You can see the different types here: http://www.srh.noaa.gov/jetstream/doppler/vcp_max.html

My guess is that the radar showing the precip was on clear air mode, which is more sensitive to lower reflectivities and thus would show more on the radar. The other radar was probably running on precipitation mode.

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I did not know that. I just assumed distance was a variable. Thanks for the article link.

So when I look at a national radar such as one from Accuweather, what am I looking at? Is it a combination of a bunch of radars? So when using Pykl3 should I switch around to the 3 radars in ND to guess what is happening?

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Any map that displays multiple radar sites at the same time almost always has it as a "composite" radar. Basically, whatever reflectivities from the various radars gets plotted on the map, though there are algorithms that will smooth and filter out the different radar signatures to make it one smooth image. These composite images are things you want to avoid when looking at light precipitation, as it can often appear overdone. It is always better to use a single radar site that is closest to you (unless it's broken or obstructed).

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