There is a small influence
on hurricane formation but there is no evidence that the NAO has long multi-decadal cycles (separate from a small forced response from the oceans or potentially from stratospheric processes)-- it is best characterised by slightly red noise.
And because it tends to ride dry desert air (duh), it can put a damper
on hurricane formation.
Hurricanes are likely to become fewer in number, but fiercer in nature according to two recent studies assessing the impact of climate change
on hurricane formation.
SST is not the only influence
on hurricane formation.
A confluence of factors, including abundant sinking air and dry air, and possibly dust flowing out of North Africa's Sahara desert, kept a lid
on hurricane formation in 2013, according to many cyclone experts.
Those patterns «have a very, very different impact on the tropical climate and, most important,
on hurricane formation,» he says.
Not exact matches
Such polygonal
formations have been observed in the center of major
hurricanes on Earth, says Barbosa Aguiar, though they quickly dissipate.
El Niño is a key factor in making
hurricane seasonal forecasts because the changes in atmospheric patterns over the tropical Pacific that it ushers in have a domino effect
on patterns over the Atlantic, tending to suppress
hurricane formation.
That doesn't mean more
hurricanes everywhere, though: While El Niño tends to boost activity in the Pacific Ocean, it clamps down
on storm
formation in the tropical Atlantic.
In a TV program
on climate change, Jeff Donnelly, a geologist using seabed layers to track past
hurricanes, takes the actor Ian Somerhalder into the «Bue Hole»
formation in the Bahamas.
Possibly, this forming El Nino also had an impact
on formation of tropical storm systems in the Western Atlantic this past
hurricane season.
It is my understanding that the
formation of
hurricanes is largely dependent
on the presence of a baseline minimum (absolute) temperature.
The perceptible (and perhaps measurable) impact of global warming
on hurricanes in today's climate is arguably a pittance (or noise) compared to the reorganization and modulation of
hurricane formation locations and preferred tracks / intensification corridors dominated by ENSO (and other natural climate factors).