The 2011 Atlantic Hurricane Season

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  • Hurricane Irene on the 26th August 2011, as it approaches North Carolina. Source: NASA.

    Flood damage caused by Hurricane Irene along Cape Hatteras, North Carolina. Source: NASA.

    Sediment flux into New York harbour produced by flood waters from Hurricane Irene. Source: NASA.

    Hurricane Katia photographed 320 miles south-west of Bermuda on the 7th September 2011. Source: NASA.

  • The 2011 Atlantic Hurricane Season
    17.12.2011 14:54

     

    The 30th of November officially marked the end of the 2011 Atlantic hurricane season. The season was rather active, with 19 tropical storms in total. Of these 19 names storms, 7 became hurricanes, with 3 reaching major hurricane strength (i.e. sustained winds greater than 110mph). The 2011 season was the third most active in terms of named storms, with the same number as last year; and the same number as both 1995 and 1887. There were 8 more named storms than 1944-2010 average, but as many of the tropical storms failed to make hurricane strength, there was only one more hurricane in the North Atlantic this year than usual.

    Weather organisations around the world release forecasts in the spring and early summer for the number of tropical storms and hurricanes for the coming season. Predictions ranged from 13-17 named storms and between 7-9 hurricanes, with around 3-4 major hurricanes. Therefore it can be seen that, although the forecasts underestimated the number of named storms this year, the forecasts for the North Atlantic did a reasonable job at predicting the number and severity of hurricanes.

    Probably the most notable hurricane of the season was Hurricane Irene. Hurricane Irene was the ninth named storm of the season, and was both the first hurricane and first major hurricane of 2011. It formed on the 21st August to the east of the Lesser Antilles. It then rapidly strengthened to hurricane strength as it made landfall in Puerto Rico, causing flooding and the death of at least one person. The storm then continued to strengthen to category 3 status with one minute sustained winds of 120mph as it tracked north through the Turks and Caicos Islands and the Bahamas. The storm then tracked along the Eastern Seaboard of the United States, making initial landfall in North Carolina. It then tracked back over open water, and weakened to tropical storm strength as it made landfall at Coney Island in New York. Significant flooding then occurred as the storm tracked in land across upstate New York and Vermont. In total 55 deaths were attributed to the storm, with 47 of these in the United States. Overall losses caused by the storm in the United States alone were estimated to be $10 billion. This was the deadliest hurricane season in the USA since the record-breaking year of 2005, and only the second deadliest in the last 20 years, with 63 deaths in total.

    Two ex-hurricanes also tracked across the Atlantic to impact the weather across the British Isles. Both Hurricane Katia and Hurricane Ophelia transitioned into intense extra-tropical cyclones, bringing strong winds and heavy rain at the start of autumn.

    By: Chris Burton