The American Meteorological Society Glossary of Meteorology defines the mesoscale as, “pertaining to atmospheric phenomena having horizontal scales ranging from a few to several hundred kilometers.” That characterizes features with sizes ranging from downtown Milwaukee to the entire state of Wisconsin! On the mesoscale, atmospheric forces associated with pressure variations, curved air flow, and the Earth’s rotation, are all important to varying degrees.

Some of the highest-impact weather phenomena, including thunderstorms, squall lines, tropical storms and hurricanes, intense snow bands, and even the placement of the rain-snow transition line, are mesoscale features. So too are more benign features such as the lake breeze that cools near-lakeshore areas in spring and summer. For many in the field, experiences with a mesoscale feature at a young age spurred a lifelong interest in meteorology.

Recent advances in our abilities to observe and use high-resolution numerical models to simulate the atmosphere have driven significant advances in our understanding of high-impact weather features, although much remains yet to be discovered. Independent of their impacts, the short space and time scales over which mesoscale features are found makes these features and their impacts particularly challenging to forecast more than a few hours ahead of time – at best!

Led by Profs. Clark Evans and Paul Roebber, faculty and students at UWM are at the forefront of the high-impact weather research and operations communities. Some of our recent research has quantified limits on thunderstorm formation and mesoscale convective system predictability, developed methods to predict mesoscale convective system track shifts, and determined what causes a mesoscale convective system’s rear-inflow jet to descend to the surface. Please contact us if you’d like to learn more!