I just returned from the Severe Local Storms conference in Savannah, Georgia, put on by the American Meteorological Society. Lots of neat stuff there--derechos and bow echos, new radar and satellite techniques for exploring storms, advances in forecasting and model development--but I'm mainly there for the tornado research.
So, a few neat non-technical things that may be of interest:
1. The intensity and size of the mesocyclone (mid-level circulation that causes the familiar "hook echo" and results in a tornado warning being called on a storm) seems to have no statistical link whatsoever to whether or not a tornado will form, nor its size and strength. Nor is there any statistically demonstrable link between the size and intensity of the tornado itself. Nor is it true that the weaker the tornado, the more likely it is to happen--there seems to be a roughly Gaussian distribution of tornado intensities, centered on about the EF2. Nor is there much evidence that the tornado either starts from the ground and develops upward, nor does it start from the cloud base and descend downward. Basically the lowest kilometer of rotating air (from the mesocyclone) suddenly all at once contracts into a tight tornado vortex. At least, that's the way it looks now.
2. For awhile, we've been able to divide the tornado into a few different regions. There's the core, usually visible as a condensation funnel. There's the corner, where the core hits the ground. And there's the inflow, which is the area near the ground where the air flows directly into the tornado, with not much rotation. One thing that is becoming evident, as we are able to get measurements from close to the tornado, is that this inflow region is very shallow. Possibly under a few meters. Also, there's some neat work on simulating corner flow going on--that's another mystery. There's no way for us to see it with a radar--we're going to have to get a direct hit with the TIV or the StickNet or something.
I could go on and on, but I think that'll do for now. Next summer there's a huge field project that will allow us to collect all kinds of great data (weather permitting).