Thursday, November 11, 2010

Chasing mythology - 1

A persistent myth associated with storm chasing is that by getting measuring systems into tornadoes, this provides data for research that ultimately will lead to saving lives. I see this myth repeated enough in media interviews to become something of a mantra for everyone out there chasing tornadoes, both privately and for actual scientific programs like VORTEX-2. It usually is coupled with the notion that such research will increase tornado warning lead times, and the result will be lives spared.

Putting scientific instruments into tornadoes involves considerable risk - we see this on the TV soap opera "Storm Chasers" on a routine basis. It's not inconceivable that chasers could be seriously injured or killed in such attempts. In fact, the more risks taken, the more likely such casualties become. But what's the potential benefit of learning more about what goes on inside tornadoes? I think obtaining such measurements is an important way to learn more about tornado dynamics. But - I have no reason to believe that an increased knowledge of tornado dynamics will have any impact whatsoever on the issue of providing improved tornado warnings!

As I've written elsewhere, tornado warnings for the types of tornadoes most likely to cause casualties are already pretty good, for the most part. Most tornado fatalities occur in association with tornadoes for which the warnings were out well in advance, rather than with those tornadoes occurring with little or no warning. Casualties from tornadoes for which no warning was given are not unheard of, unfortunately, but only comprise a relatively small minority of tornado casualties. The tornadoes most likely to cause casualties are violent, long-track tornadoes that only occur rarely without being anticipated well in advance!

Moreover, having a lot of knowledge of tornado dynamics does nothing obvious that will improve our ability to anticipate which storms will go on to produce tornadoes. It seems evident to me that studying the effect (the tornado) is not likely to provide much help without knowing a lot more about the cause (the storm that produces the tornado). The single biggest issue confronting those responsible for issuing warnings (i.e., National Weather Service forecasters) is how to recognize in advance:

(1) which storms will go on to become tornadic,
(2) when such storms will begin to produce tornadoes, and
(3) when such storms will stop producing tornadoes,

with high confidence (and accuracy). As of this moment, our attempts to do so in the real world are not always very accurate - we issue far too many false alarms because we generally prefer to warn for a storm that doesn't produce a tornado, rather than to miss putting out a warning for a storm that does become tornadic. No one ever is killed by a non-event.

This uncertainty is not about the tornadoes themselves (and their inner workings) but is all about the storms from which tornadoes are produced. If someone wants to improve tornado warnings, we need to learn precisely why most severe storms don't produce tornadoes, and how to recognize that with some reasonable degree of confidence. It's at least as difficult not to issue a tornado warning (when none is needed), as it is to issue that warning (when it's appropriate to do so).

When people justify the risks they are taking in order to obtain data inside tornadoes, it's basically not true that such research will lead to saving lives in the future. There may be perfectly valid reasons to learn about tornado dynamics, but saving lives simply isn't among them.