NotOfficially

So I came across this case right next to Whiterun. The grass itself is vanilla. This is a clean installation, and the only thing that affects weather is NAT 2.0, paired with Rudy's ENB and Particle Patch. Admittedly, it's been years since I last played the game, and I only re-installed SE three days ago, at which point I started modding and testing, and have no recollection of whether vanilla grass behaves this way under strong wind. Can someone confirm whether this is vanilla behavior?