Hurricane Michelle, it seems, has made her exit, and will now dissipate quietly into semi-oblivion, being remembered only in Cuba and the record-books. She was preceded to this fate earlier this year by Allison, Barry, Chantal, Dean, Erin, Felix, Gabrielle, Humberto, Iris, Jerry, Karen and Lorenzo. Noel, as I write, is hovering in the wings, ready to fret and strut his hour upon the stage, and we would expect him to be followed by Olga, Pablo and possibly Rebekah. It may happen, should the season be particularly prolific, that Sebastien, Tanya, Van and Wendy will put in a brief appearance before the curtain finally descends.
Michelle at its peak became for a time a hurricane of category 4 on the Saffir-Simpson scale of hurricane intensity. This scale, which categorises storms in terms of "stages" that run from one to five, indicates the potential of a hurricane to cause damage to life and property. It was devised in the early 1970s by Herbert Saffir, a consulting engineer who specialised in wind damage to buildings, and Robert Simpson, a former director of the US National Hurricane Center in Miami. Any individual hurricane may pass through one, several or all of the stages on the scale.
A hurricane at stage 1 on the Saffir-Simpson scale is comparatively harmless. It may lop a branch or two from trees and bring down some power-lines, but its winds are no stronger than 90 mph. By stage 2 it will have winds of more than 100 mph, and a few trees begin to fall. At stage 3 the damage becomes relatively widespread, and affects buildings and other structures, while stage 4 brings winds to 150 mph, with extreme damage and the doors and windows of buildings in the storm's path being almost totally destroyed. Stage 5 is catastrophic: buildings in its vicinity are devastated, winds exceed 160 or 170 mph, and on coasts storm surges approaching 20ft can be expected.
Hurricane Andrew, which hit southern Florida in 1992, and Hugo, which struck the south-eastern United States in 1989, were both category 4, and therefore, despite the record damage they occasioned, comparable in their destructive power to Hurricane Michelle. Hurricane Mitch, on the other hand, which caused mudslides, flooding and many thousands deaths in Central America in 1998, and which at its peak produced sustained surface winds estimated to have been in excess of 180 mph, was a storm at the top of the Saffir-Simpson scale, a full category 5 hurricane.