Abstract
A simple analytical expression is developed to relate the energy required to initiate moist convection to boundary-layer properties. This expression and exploratory regression are applied to data from the National Hail Research Experiment to discriminate between environments leading to cumulus congestus and well-developed hail-producing thunderstorms in northeast Colorado.
In this semiarid region, the parcel stability below the lifted condensation level is greater in environments leading to hail-producing thunderstorms compared to environments producing only cumulus congestus, as has been found in previous studies. As a result, boundary-layer properties have a multiplicity of contrasting influences on the severity of moist convection. For example, convection severity in this region generally increases with increasing low-level moisture. However, for a fixed mixed-layer depth and temperature, convection severity increases with decreasing low-level moisture because such a decrease increases the parcel stability below the condensation level.
