Super cyclonic storm (IMD scale) | |
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Category 5 (Saffir–Simpson scale) | |
Visible satellite image from 06:23 UTC on April 29, 1991. The cyclone was a Category 4 cyclone, and was rapidly intensifying, when this image was taken.
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Formed | April 24, 1991 |
Dissipated | April 30, 1991 |
Highest winds |
3-minute sustained: 240 km/h (150 mph) 1-minute sustained: 260 km/h (160 mph) |
Lowest pressure | 918 hPa (mbar); 27.11 inHg |
Fatalities | 138,866 total |
Damage | $1.7 billion (1991 USD) |
Areas affected | Bangladesh |
Part of the 1991 North Indian Ocean cyclone season |
The 1991 Bangladesh cyclone (IMD designation:BOB 01, JTWC designation:02B) was among the deadliest tropical cyclones on record. On the night of 29 April 1991 a powerful tropical cyclone struck the Chittagong district of southeastern Bangladesh with winds of around 250 km/h (155 mph). The storm forced a 6-metre (20 ft) storm surge inland over a wide area, killing at least 138,000 people and leaving as many as 10 million homeless.
During April 22, 1991, an area of westerly winds and persistent cloudiness within the equatorial regions of the North Indian Ocean spawned a large tropical disturbance over the Bay of Bengal. The system was subsequently declared a depression by the India Meteorological Department (IMD) early on April 24, as the cloud mass associated with the system encompassed most of the Bay.
The tropical storm continued slowly northwestward, slowly strengthening to a cyclone-strength storm on the 27th. The cyclone moved between a high pressure system to its northwest and east, and as mid-level westerlies met up with the storm, the cyclone moved northeastward. The westerlies enhanced upper level outflow, and in combination with warm water temperatures the cyclone steadily strengthened to a major hurricane on the 28th.
On the 28th and 29th, as the system increased its speed to the north-northeast, the cyclone rapidly intensified to 1-minute sustained winds of 160 mph (260 km/h), the equivalent to a Category 5 hurricane. Late on the 29th, Cyclone 02B made landfall a short distance south of Chittagong as a slightly weaker 155 mph (250 km/h) Category 4 cyclone. The storm rapidly weakened over land, and dissipated on the 30th over southeast Asia.
At least 138,000 people were killed by the storm, with around 25,000 dead in Chittagong, 40,000 dead in Banshkali and 8,000 dead in Kutubdia . Most deaths were from drowning, with the highest mortality among children and the elderly. Although cyclone shelters had been built after the 1970 Bhola cyclone, many had just a few hours of warning and did not know where to go for shelter. Others who knew about the storm refused to evacuate because they did not believe the storm would be as bad as forecast. Even so, it is estimated over 2 million people did evacuate from the most dangerous areas, possibly mitigating the disaster substantially.