A baseline climatology of several parameters commonly used to forecast deep moist, convection was developed using an extensive sample of upper air observations. Previous climatologies often contain a limited number of cases or do not include null cases, which limit their forecast utility. Three years of evening (0000 UTC) rawinsonde data, approximately 60,000 soundings, from the lower 48 United States were evaluated. Cloud-to-ground lightning data and severe weather reports from Storm Data were used to categorize soundings as representative of conditions for no thunder, general thunder, severe, significant hail/wind, or significant tornado.

Among the detailed calculations were comparisons between both convective available potential energy (CAPE) and lifted condensation level (LCL) using a most unstable versus a mean layer 100 mb parcel. Lapse rates for several different layers were inspected to determine the utility of using static stability versus CAPE to forecast storm severity. Lastly, low level shear was studied in an attempt to distinguish between severe and significant tornado episodes.

One of the major findings is a very significant difference between 0-1 km above ground level (AGL) magnitude of vertical wind shear for significant tornado episodes versus the other four categories. Significant differences are also noted between (LCL)/mean layer LCL (MLLCL) heights AGL for significant tornado events and the other convective categories. Using a combination of 0-1 km AGL shear and MLLCL heights AGL shows enhanced skill in objective tornado detection.