In this paper we explore the possibility of establishing predictive relationships between statistical characteristics of rainfall at the mesoscale (approximately 102 to 104 km2) and representative meteorological parameters of the storm environment. To increase the usefulness of these relationships and, in particular, to explore their use in subgrid-scale rainfall parameterization, special attention is given to statistical characteristics of rainfall that are scale invariant, i.e., are constant at least within a significant range of scales. The main contributions of this paper are the following: (1) we establish the presence of statistical (simple) scaling in “standardized rainfall fluctuations” (derived from rainfall intensities via an orthogonal wavelet transform and normalization by local means) and (2) we establish empirical connections between statistical and physical storm characteristics by quantifying relations between the scaling parameters and kinematic and thermodynamic indices of the prestorm environment. The data used for this analysis are rainfall events and corresponding soundings observed during the PRE-STORM experiment (May and June 1985) over Oklahoma and Kansas. The developed relationships are applicable to midlatitude mesoscale convective systems, which are the major rainfall producers over most of the Global Energy and Water Cycle Experiment (GEWEX) Continental International Project (GCIP) region, and are envisioned to play a key role in disaggregating rainfall (predicted by mesoscale numerical models) to subgrid scales for runoff prediction and other hydrologic applications.