The timewave screenshots come from this website. You can read more details about what they are and how they're calculated over there.
http://www.fractal-timewave.com/index.php
tl;dr: Drops = Happenings.
Since I started following the calculator regularly last year, it correctly predicted the dates of Charlottesville and Las Vegas. There was also a drop on 10/28 (day of the first Q comment). Also, take a look at the September 2001 graph sometime if you want to see a crazy timewave chart.