The Rapid Refresh (RAP) model output and PECAN observations were used to examine the atmospheric conditions and evolution of the LLJ in the PECAN domain leading to this event. The RAP model was selected because it provided a clear signal of CI occurrence in eastern Kansas (the RAP actually over-predicted the spatial extent of the convection, but was correct in the longitudinal placement of much of the CI). An investigation of RAP forecast fields thus provided a convenient starting point for studying what appear to be subtle processes involved in the event. The RAP forecast indicated that slight isentropic lift and differential moisture advection caused by a veering with height LLJ destabilized the CI region. In addition, the convergence on the eastern flank of the LLJ increased as the LLJ veered with time which aided in initiating the convection.
The Weather Research and Forecasting (WRF) model was also run for this CI case. It provided better spatial and temporal resolution of the LLJ and CI than the RAP. Back trajectories were computed to determine how air parcels were lifted across the LLJ axis. In addition, due to the over-amplified CI forecast by the RAP, a boundary layer scheme sensitivity study was conducted to identify which scheme produced the most accurate LLJ and CI for this night