Although not known for widespread severe weather, the Great Lakes are known for convection in the form of lake-effect snowstorms and lake breeze initiated thunderstorms. Cloud-to-ground flash density graphics created using National Lightning Detection Network (NLDN) data from 1989-2005 offer a glimpse into the lightning climatology of the lower Great Lakes. These flash density graphics may be useful in forecasting the location of lake breeze convective initiation and lightning in lake-effect snow.

For the full year, the maximum flash density is located over western Pennsylvania, and Ohio. A general decrease in flash density is observed from south to north. Minima are observed in the Finger Lakes region, central Pennsylvania, over Lake Ontario, and in extreme northern New York. The winter (December, January, and February) climatology shows higher flash density in southwest to northeast bands along the north and east shores of Lake Ontario during the nighttime hours (00-12Z). Similar banding is seen near the east shores of Lake Huron and the Georgian Bay. The origin of these bands is believed to be lightning in lake-effect snowstorms, but will be investigated in depth in future research. The south shores of Lakes Erie and Ontario show higher flash density during the spring (MAM) and summer (JJA) months in what is likely the lake breeze convergence zone. There is an impressive enhancement in flash density along the south and east shores of Lake Ontario in the fall (SON), which is believed to be from lightning in early lake-effect storms. These storms tend to be high in graupel content.

Future work includes a more thorough investigation of lightning in lake-effect snowstorms. An attempt will be made to filter out lightning data from non-lake-effect events so that we can create flash density graphics only including lake-effect generated lightning. This will give us insight to areas more prone to this phenomenon.