I saw that once in my back yard while living in the Texas Panhandle. I decided to burn my grass that spring rather than thatch it. What I didn't think about was how dry it was, and when I set the grass on fire, it burned so fast and hot, it created a small vortex about 6 feet tall. Scared the hell out of me and the water hose was turned on and the idea extinguished. I was afraid it would take off thru the neighborhood, even though I had a 6 foot cedar fence surrounding the yard. LOL!