Four hundred and sixty-eight 0000 UTC proximity soundings were examined in an attempt to find parameters that may discriminate between significant tornadic and significant non-tornadic environments. Significant severe weather is defined as a storm having an F2 or greater tornado, 2.00” hail or greater, and/or 65 knot wind speeds or greater. The data set was constructed between the dates of September of 1993 through December of 1996. In this study, proximity is defined as a significant severe weather event that occurred within 100 nm of a United States rawinsonde site between 2100 UTC and 0300 UTC (six hour time period centered on 0000 UTC launch).

It was shown that low-level shear and mean layer lifted condensation level heights were the best discriminators in identifying significant tornadic environments versus significant non-tornadic environments.