May 28, 2015 storm clouds building up (30x time lapse)

What was nice and warm weather earlier this day turned into near-severe weather (severe in some parts) with heavy rain. One indication of this is rapidly rising cloud tops that build up in height quickly. This is caused from strong updrafts, typically associated with big storms. At 30x time, it's very easy to see the clouds building up, and very rapidly. It was even noticeable in real time if you watched carefully enough.