Initiation Mechanisms of Nocturnal Convection without Nearby Surface Boundaries

Nocturnal convection is common over the central and southern Great Plains during the warm season. Much of this has been attributed to eastward propagating systems, but there are systems that initiate at night over the Plains. Three location-based CI modes were identified in a 20-year climatology of nocturnal CI and one mode stood out from the rest: events that initiate without a nearby surface boundary. Forecasters have recognized these events and have associated them with the nocturnal low-level jet, but there are few studies of these events in the literature. This study utilizes information obtained in the 20-year climatology, investigates observational data via case studies, and utilizes WRF simulations to identify mechanisms that may contribute to the initiate of systems without a nearby surface boundary. Three cases, each likely having a different initiation mechanism, will be shown. Preliminary analysis indicates that features such as mid-tropospheric warm advection, a mid- tropospheric moisture maximum (from earlier convection upstream), and the evolution of the nocturnal low-level jet may contribute to nocturnal CI.