Application of a Convective Plume Model to Prediction of Thunderstorms

The numerically calculated height of a steady-state model of a convective plume, which relies on the entire sounding of temperature and humidity above the assumed cloud base, is considered to be a measure of the thermodynamic predisposition of the atmosphere to convective overturning. The plume height is evaluated as a predictor of summer thunderstorms at Tampa, Fla., and is found to contain more forecast skill than a combination of two simpler and more familiar predictors, the Showalter Index and the precipitable water depth. In absolute terms, however, the skill is modest. Skill is somewhat improved when a simple measure of the zonal geostrophic flow over the Florida penninsula is considered as a predictor together with the height of the model plume, but it is suggested that a major portion of skill, not yet within reach, resides in prediction of the mesoscale systems in wwhich convection is organized.