Examining the land-lake-atmosphere interactions of the May 5, 2003 severe weather event over southwest Michigan

In this study, the land-lake-atmosphere interaction of the Great Lakes region in the United States is examined from a case study in early May 2003. During this event, a line of cumulus clouds formed several kilometers inland from Lake Michigan over southwest Michigan. These clouds eventually evolved into a line of severe thunderstorms that propagated to the east, resulting in the formation of a tornado over southeast Michigan. This type of convective initiation has been observed by forecasters in the area, and can be a high impact event in terms of public safety and water budget in the region. The rainfall from these events does leave a rain shadow parallel to the shore tens of kilometers inland. Depending on where this rainfall initiates, it can have impacts on the agricultural industry near the Lake Michigan shore.

The thermodynamic and dynamic structure leading to the convective initiation of this system is explored through a series of 400m horizontal resolution Weather Research and Forecasting Model (WRF) simulations with 101 vertical levels. Lake surface temperatures are altered in subsequent simulations to test the sensitivity of this type of storm initiation to lake surface properties and the depth of the stable boundary layer over the water, as well as to simulate future climate scenarios. Understanding this fine-scale feature is important for evaluating future climate simulations over the Great Lakes region. Existing climate models may not accurately represent this land-lake-atmosphere interaction over the region due to lower horizontal resolution, which could lead to discrepancies in distribution and intensity of rainfall.