Strange weather question

A few weeks ago, driving back toward Dallas from San Antonio I think I
may have seen something very strange... possibly.

I'm not completely sure.
Nut it did seem like it...

It was a bizarre weather day.
Snow on the blooming blue bonnets the day before.

Somewhere just north of Waco I hit a huge storm cell.
Visibility down to about 100 yards in heavy rain.
Traffic was light (gee?) and down to 25 mph or so for a while.

Out of the corner of my eye I saw something that looked like a black
stripe - going UP!

My first thought was "twister!", but it wasn't.

When I glance that way, it happened again.

It looked sorta like the after image of a lighting bolt - but no bright
flash of light.

And it went from the ground up.

The same way a lightning strike looks like it comes from the sky
down...

I've seen film of the blue and red jets that sometimes spurt out of the
tops of clouds when lightning is around.

But I've never heard of this phenomenon before!

Darkening????

Anybody have a clue???

Richard