Why does the barometer rise instead of fall during a northeaster off the Atlantic coast?
The famous and usually nasty “nor’easter” blows from the northeast, against the prevailing southwesterly flow of the Gulf Stream as it flows up the East Coast. A low-pressure area offshore creates strong winds that rotate counterclockwise around the low (sometimes referred to as “left around a low”), accounting for wind direction and intensity. It may appear that the pressure rises, but remember that all air pressure readings are relative to other air pressures. As the center of the low-pressure area, the area of the lowest pressure, passes and moves away, the pressure “rises,” but it is still a low-pressure area relative to other air masses.