‘The active hurricane era that brought us Katrina and Sandy may be over’ – ‘2015 season running at just 50% of normal’
'There’s evidence to suggest that the painfully memorable, two-decade era that brought some of the most intense hurricanes on record — and some the most active hurricane seasons — is coming to a close...Over the past two years we’ve seen incredibly low hurricane activity, and the 2015 season is running at just 50 percent of normal to-date.'
During this positive phase, when ocean temperatures are warm and ripe in the tropical Atlantic, pressure and wind patterns are also altered in such a way that favor Atlantic hurricane formation and intensification. This pattern was also seen in earlier historical hurricane periods, and is likely driven by fluctuations in the Atlantic’s warm water conveyor belt, the thermohaline circulation, which is driven by the ocean temperature and its salinity.
But in 2013, this pattern changed considerably, with colder than average water emerging in the northern and tropical Atlantic, while warm water developed off of the East Coast. This shift leads us to ask if the AMO is driving active and inactive hurricane regimes, and if so, does this mean we have indeed entered an inactive period.