The Frequency and Intensity of Great Lake Cyclones

Abstract

Cyclones are an important feature of the Great Lakes region that can have important impacts on shipping, lake temperature profiles, ice cover, and shoreline property damages. The objective of this research is to analyze the frequency and intensity of cyclones that traversed the Great Lakes region, the changes of these characteristics since 1900, the interrelationship of cyclone frequency and intensity, and their relationships to circulation patterns and regional temperature and precipitation. Significant increases in the number of strong (≤992 mb) cyclones over the twentieth century were found for the annual, cold season, November, and December time periods. In contrast, the frequency of all cyclones in the annual and warm season time series and the central pressure of all cyclones in the annual, cold, and warm season time series displayed significant decreases from 1900 to 1939. Relationships between cyclone frequency and intensity and between cyclone and anticyclone frequency and intensity suggest that there is a partial compensation within the region. As the number of cyclones increases, their intensity decreases. As the number of cyclones increases, so does the number of anticyclones. And, finally, as the cyclones become stronger, so do the anticyclones. Comparisons with the Pacific?North American teleconnection index indicate that lower (higher) cyclone frequency is associated with more zonal (meridional) flow. Comparisons of cyclone characteristics with temperature and precipitation in the Great Lakes region shows that cyclone frequency is inversely related to temperature and directly related to precipitation in most month and season categories. In contrast, the relationships between cyclone intensity and climate variables are inconsistent.