Sometimes you don’t notice something until it is pointed out to you, then you see it everywhere. That was the case for me when the near-ubiquity of clear slots near tornadoes was pointed out a few years ago. Suddenly, I began to (legitimately) see them everywhere. The feature was there, just completely overlooked. I expect a similar effect after learning about reflectivity tags at the Central Indiana Severe Weather Symposium in March.
Reflectivity tags are hardly new. The concept appears to have been introduced in a 2006 paper by Llyle Barker. The basic idea is that a small blob of reflectivity overtaking an area of rotation is often an indicator of tornado formation or intensification. Ed Shimon’s presentation at the Symposium pointed out how the Washington, IL tornado of November 17 grew from a small tornado into a neighborhood-leveling monster when the reflectivity tag passed.
There’s a danger in over-relying on the new shiny you’ve just picked up of course. The vast majority of storms still don’t produce tornadoes. I suspect that the majority of storms that feature reflectivity tags also don’t produce tornadoes. The presence of a fast-moving tag shouldn’t mean immediate panic. At the same time, it’s another piece of information to consider when watching storms.