Swaying in the Wind

I'm currently in my office on the 25th floor of the U.T. Austin Tower and a thunderstorm is blowing through Austin. According to NOAA the wind is 25-35 MPH, gusting to 50 MPH. The building has begun to oscillate very slowly. Pictures hanging on my wall are moving back and forth, a christmas ornament hanging above my desk is moving in small circles, and the panes of glass in the window appear to be flexing in and out. I've been in the Tower for years, but have never felt it move until now. Wild.