My dad always called it Desert Classic. He was really freaking good at it but it didn't really get popular until after he died.

It's focused mainly around the thumb and index finger, where you try to strum down with the index finger, only adding in additional fingers fluidly on the downstroke to add dynamics, then grabbing back up with a brush-like stroke back toward your thumb as if there was an invisible guitar pick you were trying to grab. More advanced styles of this include more of the palm slapping against the strings as well as the body of the guitar. One of my favorite players who has taken this style to the next level by adding alot of fret hand tapping is Andy McKee. It's different than this now because of how he as well as few other have evolved it, but if you search him on YouTube you will see alot of lesson style videos in the side bar to get you started. I'm sure there are better ways to find some tutorial videos but I'm not sure of anyone who plays this style in a more traditional way.