Which phenomenon results typically in heavy snowfall and blizzards?

The phenomenon that typically results in heavy snowfall and blizzards is associated with Nor'easters. These are powerful storm systems that form along the East Coast of the United States, typically during the winter months. They are characterized by strong winds and intense moisture coming from the Atlantic Ocean, which can lead to significant snowfall, especially when conditions are right, such as cold air being in place.

Nor'easters often bring heavy snow and can generate blizzard conditions, which are defined by sustained winds of 35 mph or more combined with visibility reduced to a quarter mile or less due to falling or blowing snow. Because of the specific geographic and meteorological conditions that favor heavy winter storms in this region, Nor'easters are particularly well-known for producing such extreme weather events.

In contrast, hurricanes focus more on intense wind and rain during warmer months; monsoons are seasonal rain patterns associated with the Indian subcontinent and other areas, while El Niño is a climate pattern that can influence weather patterns globally but does not directly cause heavy snowfall and blizzards on its own. Thus, Nor'easters stand out as the clear source of heavy snow and blizzard conditions, which underscores the correctness of this choice.