Hurricane Sandy is a tropical weather system. Why does it bring snowfall to Canada?

Before Sandy arrived, there was a high-voltage system hovering in northern North America for a long time. The easterly airflow prevails in the south of this system. The airflow passes through the Great Lakes and the North Atlantic, and is supplemented by warmer and wetter water vapor, which is easy to form rain and snow. Sandy's arrival catalyzes the rain and snow weather, because Sandy is a low-pressure system, and the easterly airflow prevails in the north of the system, which brings the continuous water vapor from the Atlantic Ocean to the south of the high-pressure system and intensifies the movement of warm and humid airflow, thus bringing heavy rain and snow weather to eastern Canada and the northeastern United States.