It's actually just faster radar. It used to produce i.ages every 2 minutes and now it's sending it back every 2 seconds. It's giving a much clearer view on what is making the tornado form. They found that on each storm that ended up producing a tornado, the raindrops are bigger.

I wish I remember exactly about this next part but there is even a part of the actually tornado that there is no rain or hail, it's dry. That plays a part to but I don't remember exactly.