Does rain fall preferentially over wet or dry soils?

Abstract:

The impact of soil moisture on precipitation, particularly at sub-daily time scales, is not well understood. We use in situ soil moisture observations and satellite-based precipitation estimates to examine if afternoon convective precipitation falls preferentially over wet or dry soils in Oklahoma. Convective precipitation events during the warm season (May – September) in Oklahoma from 2003 and 2012 are categorized by how favorable atmospheric conditions are for convection, as well as the presence or absence of the Great Plains low-level jet. Our results show convective precipitation falls preferentially over wet soils when the Great Plains low-level jet is absent. In contrast, convective precipitation falls preferentially over dry soils when the low level jet is present. The results suggest that rain falls preferentially over over wetter and drier than normal soils, depending on the overall synoptic and dynamic conditions.