As the North Atlantic Oscillation (NAO) changes, it affects the trade winds, which blow from the east across the tropical Atlantic. When the NAO is high, the trade winds are stronger than normal, which in turn strengthens the Atlantic Meridional Overturning Circulation (AMOC). But at the same time, the westerly winds over New England are also stronger than usual. Together with unusually high air pressure on the northeast coast, this lowers the average sea level. It's wind and pressure that are driving both phenomena.