Using Doppler radar vortex detection algorithms to develop synthetic tornado climatologies

Tornado verification can be problematic in certain locations, such as those with low population density, in mountainous and forested regions, and where storm verication is not as actively pursued (such as in Europe and other foreign countries). We attempt to answer the question of whether radar-observed storm-scale vortex signatures (e.g., mesocyclones and TVSs) can be used as a proxy to synthetize tornado climatologies where verification is problematic.

Starting with a database of "well-verified" tornado events (43 cases with about 207 tornado reports), and the associated output from both mesocyclone and TVS detection algorithms, we determined the likelihood that particular detections are tornadic based on a variety of detection attributes (such as rotational velocity, depth, etc.). We then apply the posterior probabilities of the well-verified dataset to a test data set that is assumed to be poorly-verified (the poorly-verified data set is actually a three-year nearly-conclusive set of all the storm-scale vortex detections collected from the Pittsburgh radar during 1996-1998 - see related paper by Mitchell and Elmore). The resulting synthetic climatological values for number of tornadoes are quite similar to the actual number of reported tornadoes within the domain of the radar for the poorly-verified data set.

These results offer some optimism that radar data could be used to determine synthetic climatologies of tornadoes wherever radar data are collected. This method, coupled with other methods to synthsize tornado climatologies, might lead to the a better understanding of the distributions of tornadoes worldwide.