What Are Those Lines On The Radar?

The Weather Authority
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You may notice on hot, summer days, strange looking lines on the radar, even though there isn’t any rain.

Convective rolls as seen by radar

These are called convective rolls, and they happen when hot air tries to rise, but something is preventing that air from continuing to rise and it sinks back down to the surface. Today, high pressure across the Tennessee Valley is keeping air from rising to the point that we could create showers and storms.  Occasionally, a brief shower has popped up along one of these rolls today, but it didn’t last. These rolls don’t always happen on quiet days though. These can sometimes be seen on severe weather days before the cap breaks and storms start to fire. Essentially, those lines on radar just show that air in the atmosphere is trying to move up, but something is preventing it from rising so far up that it could develop into showers and storms.

Convective rolls are areas where shallow up and down movement is occurring

Where the air is rising up in a convective roll, clouds often form, and small insects can be caught in the rising air. That’s probably what the radar is seeing. On the side of the convective roll where the air is sinking, the skies would be cloud free.

Diagram of convective rolls in the atmosphere.

While rain chances remain slim this week, we will see some cooler air move in. We’ve got the details on how cool things get over on the forecast discussion. 


Meteorologist Alex Puckett

Facebook: www.facebook.com/meteorologistalexpuckett

Twitter: twitter.com/puckettwx

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