A Climatology of the Interaction between Short-Wave Troughs and Shore-Parallel Lake-Effect Snowstorms off of Lake Ontario

Lake-effect snowstorms can produce prolific snowfall amounts near the shores of Lake Ontario while presenting a severe hazard to public safety. Shore-parallel lake-effect snow bands are 20–50 kilometers wide and can extend inland for over 200 kilometers. While lake-effect snow is primarily a lower tropospheric event, middle and upper tropospheric features can have an impact on the evolution of lake-effect snow. In order to understand the influence of the upper troposphere on lake-effect snow, an eight-year (2007–2015) climatology of the interactions between 500-hPa short-wave troughs and Lake Ontario shore-parallel lake-effect snowstorms was developed. A short-wave trough database and single site radar data were used to analyze the change in band orientation, latitude, intensity, and inland extent before and after short-wave trough passage.

This presentation will focus on 32 Lake Ontario shore-parallel bands that existed before, during, and after the passage of a short-wave trough. As a short-wave axis approaches a preexisting snow band, there is a tendency for clockwise band rotation, a southward drift, intensification, and an increase in inland extent. After the short-wave trough axis passes the lake-effect band, there is less consistency in how the band character changes. These results indicated that 500-hPa short-wave troughs have a more predictable impact on lake-effect snow as they approach the storm than after they depart the Lake Ontario region. While changes to lake-effect snow bands may sometimes be subtle with the passage of a short-wave trough, they are still notable given that only minor changes to lake-effect snow bands can cause substantial forecast errors for these high-impact storms.