Great Lakes PBLs: Mixing it up in Lake-effect Snowstorms and Lake Breezes
The planetary boundary layer (PBL) links the earth’s surface to the overlying atmosphere by vertically transporting heat, momentum, and other constituents. In the Great Lakes region, each water and land body alters the air passing over it, resulting in a highly complex PBL - a mixture of multiple shifting mesoscale air masses.
During the Thanksgiving 2024 weekend, such PBL processes generated an impactful severe lake-effect storm, blanketing parts of Ohio, Pennsylvania and New York with up to six feet of snow. Such storms can produce some of the most extreme winter weather conditions experienced in the eastern United States. This presentation will outline what has been learned about lake-effect systems over the last few decades and highlight two particularly difficult processes to observe in the Great Lakes region: entrainment of ambient air into lake-effect systems, especially in the presence of surprisingly common elevated mixed layers, and processes over intervening land areas determining the degree to which lake-effect snowstorms over one lake impact such storms over downwind lakes.
Finally, the presentation will introduce a recent study of warm season PBL processes in the Great Lakes area. Examples of Doppler lidar, tower, radiosonde, and other observations taken during the MITTEN-CI field project will illustrate some initial findings on lake breezes and how lake-cooled air changes as it flows inland over the warm surface.