The 1997 ENSO event and implication for North American Laurentian Great Lakes winter severity and ice cover

Mild winters and below‐average annual maximum ice cover for the Laurentian Great Lakes occur during strong warm ENSO events. During the six strongest warm ENSO events since 1950 a Great Lakes winter severity temperature index and simulated annual maximum ice cover averaged 1.2°C above and 15% below a 1950–1994 average, respectively. The observed differences between the average of the strong ENSO event years and the base period average are statistically significant.