Precipitation Efficiency of Warm-Season Midwestern Mesoscale Convective Systems

Abstract

The precipitation efficiencies for mesoscale convective systems (MCS) over the central United States are calculated. During July–September 2000 and June–September 2001, 24 MCS for which sufficient data were available occurred over or near Missouri. Precipitable water fields from the hourly Rapid Update Cycle (RUC) and radar-derived precipitation grids are used to calculate the precipitation efficiency. Geostationary Operational Environmental Satellite soundings and RUC winds are used to assess the pre-MCS environment. Statistical analysis reveals that precipitation efficiency has a relatively strong positive correlation with the relative humidity in the layer between the surface and the lifting condensation level; significant negative correlations are found between the precipitation efficiency and both the convective inhibition and the environmental wind shear. The latter, inverse relationship between shear and precipitation efficiency supports the findings of previous investigators.