Historical observations show that the Atlantic Ocean undergoes long-term shifts in ocean surface temperatures, a phenomenon known as the Atlantic Multidecadal Oscillation (AMO). In 1995, a shift from the cool to the warm phase occurred, and for more than a decade Atlantic Ocean surface temperatures remained above average. However, since the second half of 2008 a remarkable shift has taken place as the Atlantic Ocean has abruptly cooled.

A cooler Atlantic may impact the upcoming hurricane season, as cooler ocean temperatures inhibit storm development. In 2005, when the AMO was near its peak warming, the most active Atlantic hurricane season on record occurred with 27 named storms. Between 2005 and 2009, there have been significant changes in Atlantic Sea Surface Temperature (SST) anomalies.

Atlantic sea surface temperature anomalies 2005 2009
© StormX

The Atlantic Multidecadal Oscillation Index has been developed by scientists to track surface temperature changes in the Atlantic. This index is correlated with tropical storm frequency; high index values indicate a warmer ocean and more tropical storms, and low index values indicate a cooler ocean and less tropical storm activity. In February 2009, the index reached a value of -0.11, the lowest observation since November 1996. If the Atlantic Ocean remains cooler than average throughout the summer of 2009, it will likely decrease activity during the upcoming Atlantic hurricane season. The Storm Exchange science team will continue monitoring the AMO and its potential impacts as the hurricane season approaches.
Atlantic MDO
© StormX