Lake-effect snowstorms generally form in convective boundary layers as cold air flows over relatively warm lakes in fall and winter. This study provides detailed numerical simulations of the spatial evolution of the boundary layer structure and mesoscale convective patterns across Lake Michigan for an intense lake-effect event observed during Lake-Induced Convection Experiment (Lake-ICE) on 13 January 1998.

This study involves simulations, starting from Eta Forecast model analyses and nested down to a 0.5 km horizontal grid, to resolve the random cellular convective structure. Comparisons of 3 and 2-dimensional depictions of model output with both visual and ELDORA Doppler radar fields will be presented. Analyses of the growth rate of the simulated boundary layer will be compared with those obtained from project aircraft and rawinsondes. Flux estimates, based on both model surface energy balance calculations and by bulk methods from the model and observations, will be discussed. Sensitivity tests are used to examine the effects of cloud –radiation interactions and latent heating in the clouds on the convective boundary layer. Observed decreases in aspect ratio of convection within the developing convective boundary layer across Lake Michigan are examined via simulation.. Differences in convective structure from cellular in northern regions to boundary layer rolls in southern regions will be considered. Issues and implications for model initialization will also be presented.