The Influence of Multiple Lake Interactions upon Lake-Effect Storms

Abstract

Mesoscale disturbances in close proximity to one another typically undergo process interactions, which ultimately may result in the formation of a disturbance on the scale of the combined mesoscale disturbances. Embedded within this combined disturbance, some semblance of the incipient individual mesoscale disturbances may be preserved, especially in instances when the individual forcing mechanisms are fixed in space, as in the case of the Great Lakes. Studies have shown that during prolonged cold air outbreaks, collective lake disturbances can originate from the organization of individual lake-scale disturbances. These collective lake disturbances may, through scale interactions, alter the behavior of the contributing individual lake-scale disturbances and the embedded lake-effect storms. Factor separation decomposition of the Great Lakes system indicates that various interactions among lake-scale processes contribute to the overall development of the regional-scale disturbance, which can modulate embedded lake-effect snowbands. Contributions from these interactions tend to offset the individual lake contributions, especially during the development of the collective lake disturbance, but vary spatially and temporally. As the regional-scale disturbance matures, lake?lake interactions then accentuate the individual lake contributions. Specifically, the modulation of lake-effect snowbands was translational, intensional, and in some instances morphological in nature. Near Lake Michigan, processes attributed to Lake Superior (upstream lake) were direct and synergistic (indirect) resulting in a time delay of maximum snowfall intensity, while processes attributed to the downstream lakes were primarily synergistic resulting in an overall decrease in snowfall intensity. Furthermore, as the collective lake disturbance matured, Lake Superior?induced processes contributed to a significant morphological change in the Lake Michigan lake-effect snowbands.