Assessing the impact of proximity sounding criteria on the climatological significant tornado environment

Proximity sounding studies typically seek to optimize several tradeoffs that involve somewhat arbitrary definitions of how to define a “proximity sounding”. More restrictive proximity criteria, which presumably produce results that are more characteristic of the near-storm environment, typically result in smaller sample sizes that can reduce the statistical significance of the results. Conversely, the use of broad proximity criteria will typically increase the sample size and the apparent robustness of the statistical analysis, but the sounding data may not necessarily be representative of near-storm environments, given the presence of mesoscale variability in the atmosphere. Previous investigations have used a wide range of spatial and temporal proximity criteria to analyze severe storm environments. However, the sensitivity of storm environment climatologies to proximity definition has not yet been rigorously examined.

In this study, a very large set (~ 4000) of proximity soundings associated with significant tornado, hail and wind reports is used to generate distributions of several parameters typically used to characterize severe weather environments. Statistical tests are used to assess the sensitivity of the parameter distributions to the proximity criteria. Implications of the results for proximity sounding methodologies are discussed. Finally, an appropriate set of proximity criteria is used to compare storm environments in different geographical regions and for different significant severe weather types.