Convective systems generated over the Great Lakes during the cool season can produce copious amounts of snow, sometimes measured in meters, and flood-producing rains. Impacts from such events on the 35 million people living near the Great Lakes can be quite large and both negative (e.g., transportation problems, injuries) and positive (e.g., winter recreation, snowplowing and repair businesses). This presentation will consider what is known about the climatic variability of lake-effect convective precipitation on both an interannual and multi-decadal time frame. Evidence for an overall increasing trend in lake-effect snowfall during the 20th century will be discussed along with conflicting predictions of whether this trend will continue or reverse in coming decades.
Impacts on local communities may be most notable in shorter-term, interannual variations in lake-effect snowfall. It would be anticipated that variations in the types of lake-effect mesoscale snowbands that dominate over the winter season can give rise to anomalous snowfall distributions. This presentation will summarize findings from our research on the various types of convective precipitation bands that form over the lakes in the cool season, particularly the less-well-understood multiple-lake bands. We will consider how mesoscale lake-effect circulations influence seasonal snowfall.