This is on the WDSU weather radar now. Check out the space between Alexandria, LA and Jackson, MS. There's something showing up as a line on the radar.
https://www.wdsu.com/weather/radar
I've never seen anything like it. I watch radar during weather events, but I'm no meteorologist.
The radar is based in New Orleans to the south, so it seems odd it would be a radar artifact. I'm gonna watch it just to see what happens.
This is WDSU weather radar in New Orleans. That's roughly 100 miles or so south of the "line".