It is hypothesized that the Great Lakes may have a direct influence on the intensity of Mesoscale Convective Systems (MCSs) that cross over them. The principal goal of this investigation is to resolve the impact of the Lakes on convection, primarily MCSs capable of producing derechos. Thirty such MCS events were identified during the period of 1995-2001. Then, radar, satellite, and surface data are examined to yield insights into environmental conditions affecting the evolution of the MCS as it passes over the Great Lake.

Initial analysis suggests that the depth of the planetary boundary layer over the Lakes is an important factor in sustaining versus dissipating MCSs. Some events appear to cross very cold water relatively unscathed and it appears as though they may become decoupled from the boundary layer thereby ingesting warm, unstable elevated air. Therefore, lake surface temperatures (LSTs) obtained from surface data (including buoy and lighthouse observations) may indeed be highly correlated to the intensity of each event. In addition, near shore environmental conditions prior to the onset of convection will be analyzed to determine whether or not changes occur in the region during the event. Structural changes of the system that may occur are detected by utilizing satellite and WSR-88D composite reflectivity imagery. This analysis provides clues to how the MCS is enhancing and being altered by the surrounding Great Lake environment. Upon determining the effects of the local environment on structure and propagation of the MCS events, conceptual models may be developed in order to illustrate commonalities within the environments and lake surface characteristics.