Sunday, February 28, 2010

supercells

I have been thinking about severe weather for my work. I have always been curious about supercells because the characteristics I have observed have been so varied. Everything from the cloud structure and radar appearance to the location of tornado (or tornado's).

What I find even more interesting is that they tend to evolve rapidly. They evolve because of a changing environment (vertical wind shear, CAPE, moisture and moisture depth). But there are also those weird days, where in a similar environment, they develop differently. In a few cases I would surmise this has occurred because some boundary has been influencing the storms.

But a paper I read hinted that there are two types of these supercells distinguished by front vs rear precipitation relative to the updraft. There are some solid objections to this line inquiry based on the known and documented differences between so-called classic supercells and Low precipitation supercell tornado threats. However, a taxonomy is only useful if the storms have a certain structure and that structure leads to some predictable behavior.

While a taxonomy appears to be worthwhile to describe these varied characteristics, what are we really trying to achieve with it?
1. Operational radar recognition of the supercell and tornado threat.
2. A conceptual model of these storm types, including their life cycle evolution.
3. Explain why some supercells produce tornado's and why some do not; why some produce many and others produce 1; why some have a predictable location of tornado occurrence and others have multiple.
4. Address: Why do tornadic supercells differ so little from non-tornadic supercells?



These challenging questions are why, once again, the VORTEX2 field project will be operating in the Great Plains this year. Hopefully a new round of data collection will offer some insights into these fascinating and destructive storms.