Numerical Simulation and Radar Analysis of a Lake-Effect Snow Event: What Goes on in Yonder Clouds?

Mesoscale numerical models have long been employed to simulate lake-effect snowstorms, with increasingly realistic model-produced features as grid resolution and parameterization schemes have improved. While numerous sensitivity tests have been reported in the literature, relatively little attention has been given to the effect of microphysical details within observed and simulated lake-effect snow bands. Here, we explore the likely presence of liquid water within early season lake-effect clouds, and whether the simulation results are sensitive to the distribution of cloud properties included in the microphysics parameterization.

Examination of an early season event in northwest Indiana on 18 November 2008 showed antecedent wind-parallel snow bands in southwest Michigan, which quickly transitioned into a dominant mid-lake snow band. The dual-polarization Valparaiso University radar data clearly captures the mid-lake band, with attendant heavy snowfall. A comparison of radar and model output microphysical characteristics is conducted. It is expected that simulated vertical profiles and cloud-level characteristics over the lake support the presence of cloud liquid water, as well as ice structures and snow. Additionally, the results are expected to not be highly sensitive to the cloud microphysics option, so long as the scheme includes cold cloud processes.