WeatherWeather Blogs


Radar cone of silence

Learning about radar data
Posted at 3:26 PM, Apr 27, 2020
and last updated 2020-04-27 16:26:51-04

One of the biggest weather tools we all use is radar. We’ve all got weather apps on our phones we check when we’re keeping an eye on a storm moving in or a band of snow headed our way. As useful and important as radar is, it also has some limitations. One such limitation is called the cone of silence.

The basic way to explain what radar does is the radar beam shoots out from the radar and when the beam “hits” something like a raindrop or hail stone, the beam bounces back to the radar. This gives us an idea of how far away the rain/storm is and how big the raindrops or hail stones are.

The dish inside the radome makes full circle rotations and also changes the vertical height of the beam ranging between 0 degrees (think straight out) and 19.5 degrees (think slightly tilted upwards), but it cannot “see” what is directly above itself. This lack of data is called the cone of silence. So, despite how it sounds, the “cone of silence” doesn’t refer to an area of space where you can’t hear anything, it's where you can't "see" anything!

Take a look at an example from the NWS Omaha radar in Valley from the storm that produced all of the pea size hail in parts of west and southwest Omaha on April 25th!

In the first image, at 4:45 pm, you can start to see the storm approaching the radar from the west to east. You can see the higher reflectivity values on the west side of the radar, and then the data disappears.

In the second image, at 4:49 pm, you can easily see the southern edge of the cone of silence as the storm continues to move over the radar.

In the last image, at 4:54 pm, the storm continues to move over the radar site and then you see the eastern edge of the cone of silence as the storm moves southeast.

We’ve got a few rain chances coming up, so if you’ve never looked for the cone of silence before, now you can and will know what you’re seeing!