I had ridden my bike out to one of my usual turnaround points out around Benbrook lake at the top of a hill. The sky was perfectly clear except for one cloud off in the distance. Then it started lighting. But the sky by me was still clear. I had brought my DSLR and a flimsy, but portable tripod. Out of about 150 shots, this one was the best of the bunch, though it still wasn't up to being challenge material, or I would have used it in the freestudy that month.
Downtown Fort Worth can be seen in the lower left corner.
I thought the storm was over the mid cities area about 25 miles away. I found out later that it was actually over the city of McKinney, which is a good 50 or 60 miles away on the far northeast side of the Dallas-Fort Worth metroplex. Someone else posted a photo on Facebook that looked like this storm was over downtown Dallas, but was still a fair amount away from there.
I read your description of shooting this. Sometimes it's just a fortunate thing to have your camera with you, even when you don't anticipate seeing anything to shoot.
Nice storm shot.