September record month for Atlantic tropical cyclones
Written by staff reporter
The US National Hurricane Center reported that September 2017 was the most active month ever recorded for tropical cyclones in the Atlantic Ocean when measuring the combined strength and duration of storms in the basin.
Hurricane Irma crossed through the northern Caribbean as a Category 5 hurricane, before making landfall in the United States to become the first Category 4 landfall in Florida since 2004’s Hurricane Charley. At least 124 people were killed or missing and hundreds more were injured, following periods of exceptionally gusty winds, high surf, storm surge, torrential rains and inland flooding. Major damage was noted in the United States, Cuba, Barbuda, the Virgin Islands, and the northern Leeward Islands.
Hurricane Maria became the second landfalling Category 5 hurricane in a matter of weeks, when it struck Dominica and grazed St. Croix. The storm later crossed Puerto Rico as a high-end Category 4 – the strongest storm to hit the island since 1932 – resulting in catastrophic damage and impacts. Additional damage was noted in the Dominican Republic and Haiti. At least 78 people were confirmed dead and many others were considered missing.
According to Aon Benfield, with assessments still ongoing for both Irma and Maria, it remains too early to provide a specific economic or insured loss estimate for each event – especially given the prolonged business interruption impact. The overall financial toll of each storm is expected to reach well into the tens of billions of dollars. In each instance, public and private insurers faced payouts considerably exceeding US$10bn.
Elsewhere during the month, Mexico was impacted by Tropical Storm Lidia, which killed 20 people when it tracked along Mexico’s Baja Peninsula, and three powerful earthquakes.
The temblors included the strongest earthquake of 2017: a magnitude-8.1 event that struck offshore the state of Chiapas, followed by a magnitude-6.2 aftershock, which together killed at least 103 people. A magnitude-7.1 earthquake then struck central Mexico, killing at least 367 people and injuring thousands more.
Total combined economic damage was expected to reach into the billions of dollars.
Steve Bowen, Impact Forecasting director and meteorologist, said: “The month of September was exceptionally busy and marked by the most active month on record in the Atlantic Ocean for hurricanes based on combined strength and longevity. The most prolific damage resulted from Hurricane Irma’s impact across the United States and the Caribbean, and Hurricane Maria’s track through the Caribbean. These events were poised to cause a heavy financial burden for federal governments and the insurance industry. Additionally, two major earthquakes and a powerful aftershock in Mexico led to catastrophic damage. When combining event impacts from July and August, the third quarter of 2017 is expected to tally as one of the costliest quarters ever registered for natural disasters.”