How warm seas powered two major hurricanes

Extraordinary things have been happening in the Atlantic. It’s rare enough to have one major hurricane this late in the year, but to have two of them appear in October is unprecedented in 165 years of weather observations.

Hurricanes Matthew and Nicole were extremely powerful storms. Matthew was the more intense, with winds reaching 160mph and far more devastating as it tore a path through the Caribbean and along the US south-east coast. No wonder that little attention was paid to Nicole until it exploded into a ferocious storm, winds reaching 130mph before it struck Bermuda.

Hurricanes tend to grow weaker as the hurricane season tails off – and the season ends on 30 November – so how did two massive storms seem to come out of the blue? One big factor was unusually warm seas.

Matthew turned from a fairly weak tropical storm to a Category 5 hurricane in just 36 hours as it passed over Caribbean waters at near-record breaking high temperatures, some 2C warmer than normal for October. Similarly, Nicole passed over exceptionally warm seas, even though it tracked much further north in the Atlantic.

Hurricanes have to to feed off warm seas for their huge energy needs, but a slow-moving hurricane passing over warm surface waters can sometimes kill itself off by churning up cold water from deep below in the sea.

Matthew and Nicole were both slow-moving, but they survived because the seas were also unusually warm well below the surface. Whether or not a warmer climate is to blame, it fits a pattern of more intense hurricanes since the 1980s.

Read more https://www.theguardian.com/news/2016/oct/17/warm-seas-powered-two-major-hurricanes-matthew-nicole-weatherwatch

Courtesy of Guardian News & Media Ltd