The North Atlantic Oscillation (NAO) is a climatic phenomenon in the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level between the Icelandic low and the Azores high. Through east-west oscillation motions of the Icelandic low and the Azores high, it controls the strength and direction of westerly winds and storm tracks across the North Atlantic. It is part of the Arctic oscillation, and varies over time with no particular periodicity.

It is one of the most important manifestations of climate fluctuations in the North Atlantic and surrounding humid climates (Wikipedia)

 

Until now, it is not clear which are the mechanisms driving NAO !

Subpolar gyre is the engine of the heat transport across the North Atlantic Ocean. The warm water current branching of the North Atlantic Drift Current in combination with the Arctic overflow create Labrador Sea current, which is the essential component of the Subpolar gyre's circulation.

 

North Atlantic Precursor is the critical factor controlling strength of the Subpolar gyre (Vukcevic).

North Atlantic Precursor has all attributes of  the mechanisms driving NAO !

Since there is about 9 year delay between the NAP and the NAO data time lines, it should be possible to ascertain the approximate NAO direction few years in advance. If correct, then indication is that the North Atlantic Oscillation would go further into the negative territory  during next few years.