Lower Michigan MCS Climatology: Trends, Pattern Types, and Marine Layer Impacts

One of the most significant summer forecast challenges for forecasters whose area of concern is downwind of a large lake (e.g., Lake Michigan) is the impact, if any, that the marine layer will have on existing convection as it crosses the body of water. The primary aim of this research is to investigate the influence of the Great Lakes (Lake Michigan in particular) on the intensity and evolution of Mesoscale Convective Systems (MCSs). Since a major MCS activity corridor lies over the Great Lakes region, it is important to understand the impact of the marine layer on MCS intensity.

The period of study runs from 1995 to 2001 and includes thirty-six MCS events which produced at least 5 severe weather reports prior to crossing Lake Michigan. A climatology encompassing the intensity trend of the MCSs, time of day, time of year, and configuration (i.e., serial versus progressive) of the MCSs as they crossed Lake Michigan will be presented. Composites of surface and upper air pattern types associated with MCS occurrence across the central Great Lakes, observed and proximity sounding analysis information and the impact of the marine layer on existing convection will also be discussed.