I think this photo has had the color adjusted, but the cloud formations absolutely happened. I know because I was watching from my office on the 32nd floor of the second tall building from the right edge. It didn't look quite this green from my vantage point but it was seriously dark. I was in a meeting when the sirens went off, followed by the severe weather app on my phone. (Weather Alert USA, $3.99 from the App Store and totally worth it)
Shortly after that our COO stuck his head in the conference room and said "everyone to the stairwell!" The next hour and a half or so was spent milling around in the interior hallway, elevator lobby and stairwell with my phone watching the radar map and listening to National Weather Service radio before finally walking down 31 floors. Shortly after that it all passed and the sun came out. Totally strange.