Lake Ontario Lake-Effect Shoreline Bands: An Investigation of the Huron-to-Ontario Connection

Visible GOES satellite imagery was used to identify lake-effect events in the Great Lakes region during a 17-winter time period (1997/1998 through 2013/2014). This information provides an unmatched understanding of the frequency and variations of lake-effect events within the Great Lakes region and also provides insight into multi-lake lake-effect events, previously termed lake-to-lake events. The influence that upwind Great Lakes have on the development or intensification of lake-effect events over a downwind Great Lake is not well understood and remains a difficult operational forecasting issue. Using the winters of 2004/2005 through 2013/2014, two groups of events were identified when a lake-effect shoreline band existed over Lake Ontario. The first group included nearly 30 events with lake-to-lake bands extending from Lake Huron to Lake Ontario and a second group contained about 200 events with a shoreline band over Lake Ontario and no visible lake-to-lake band present. Northwesterly flow over three distinct areas of Lake Huron was found for the lake-to-lake group using backward air parcel trajectories from the HYSPLIT model and a much larger variation in flow directions, dominated by westerly flow over Lake Erie and south of Lake Huron was found for the non-lake-to-lake group. North American Regional Reanalysis (NARR) composite map analyses showed two distinctive patterns in sea-level pressure, 850mb temperatures and winds, and low-level specific humidity for the lake-to-lake and non-lake-to-lake groups. More comprehensive findings from the Great Lake lake-effect climatology, HYSPLIT trajectory analyses, and NARR analyses will be presented.