Chasing a storm that wouldn't stay still

I'm in my truck on a gravel road, and the supercell ahead keeps shifting shape—every time I get close, it folds into something else, like it's playing hide-and-seek with me. The sky is that bruised purple you only see before a wedge, but there's no wind, just this heavy stillness that makes the hair on my arms stand up. I wake up before I can decide whether to turn left or right, and I'm still half-convinced I could have caught it if I'd just pushed harder.