Tighten your Snow Belt – New Efforts to Understand Lake-effect Storms in the Eastern Great Lakes

The Great Lakes directly impact weather and climate conditions over more than 1.0 million km2 in northern and central US and southern Ontario, Canada. Perhaps the greatest impacts are during the cool season, when the relatively-warm Great Lakes can generate storms with extreme snowfall rates (sometimes greater than 10 cm hr-1), strong winds, low visibilities, and cold temperatures. Lake-effect storms represent the results of development of surface-based convective boundary layers over each of the lakes and interactions between them. Many of the larger field efforts in recent decades focused on lake-effect snow storms over single lakes, such as those driven by the Great Salt Lake or Lake Michigan. However, interacting lake-induced convective boundary layers from multiple lakes, such as those occurring in northern regions of Canada or the eastern Great Lakes, offer particular challenges for forecasters and opportunities for improving scientific understanding.

This presentation will provide a boundary layer perspective on the improvement in understanding of lake-effect snow storms, and how lake-induced convective boundary layers in the eastern Great Lakes are likely to be more complicated than those to the west. It is hypothesized that upwind lakes can influence lake-effect storm evolution through both direct thermodynamic processes (e.g., “residual” layers of near-neutral stability, Mesoscale circulation patterns from upwind lakes) and indirect processes (e.g., seeding of lake-effect clouds by snow from higher-level cloud decks, etc.). Emphasis will be placed on the recently-completed 2013-2014 Ontario Winter Lake-effect Systems (OWLeS) field project, carried out in the vicinity of Lake Ontario and regions east of Lake Erie. The field phase of the OWLeS project was accomplished through the collaborative efforts of about 109 students and scientists from 16 universities, scientific organizations and NOAA National Weather Service Offices. OWLeS was primarily supported by the Mesoscale Dynamic Meteorology program of the National Science Foundation.