| Daulatpur–Saturia tornado | |
| Formed: | 12:30 UTC on 26 April 1989 |
| Fujita-Scale: | F3+ |
| Winds: | 338to |
| Season: | tornado outbreaks of 1989 |
The Daulatpur–Saturia tornado occurred in Manikganj District, Bangladesh on 26 April 1989. There is great uncertainty about the death toll, but official estimates from the World Meteorological Organization indicate that it was devastating and that it killed approximately 1,300 people, which would make it the deadliest tornado in history.[1] [2] In 2022, this tornado's status as the deadliest tornado in history was challenged, claiming it did not kill more than 922 people. The tornado affected the cities of Daulatpur and Saturia the most, moving east through Daulatpur and eventually northeast into Saturia.[1] Previously, the area that the tornado hit had been in a state of drought for six months.[1]
The Ganges Basin, comprising the entirety of Bangladesh, is frequented by severe weather.[3] Storms that are capable of producing tornadoes in this region are most common during the pre- and post-monsoon months.[4] An average of six tornadoes occur annually in Bangladesh, with peak activity in April.[5] The pre-monsoon months (March to May) display the most favorable conditions for severe weather. During this time, convective available potential energy—an indicator of atmospheric instability whereby higher values denote a greater likelihood of thunderstorms—and wind shear are conducive to the development of rotating thunderstorms.[6] Instability is greatest over West Bengal, India, and adjacent areas of Bangladesh. Storms frequently develop in this region and travel southeast across the country. These storms are locally referred to as norwesters or Kalbaishakhi.[7]
On 25 April 1989, a area of low pressure propagated over Bihar and West Bengal, India, with a trough extending east across Bangladesh and into Manipur, India. The system remained largely stationary throughout the day through 26 April. On that day, another low approached from Madhya Pradesh, and in conjunction with a ridge over China, the pressure gradient became tighter across Bangladesh. Warm, moist air flowed northeast from the Bay of Bengal while cool, dry air flowed south from the Himalayas. In the upper-levels of the atmosphere above the low, strong westerly winds from the jet stream created ample wind shear, a key factor in the development of supercell thunderstorms capable of producing tornadoes. The jet stream became particularly intense on 26 April, with a sounding from Dhaka observing 240round=5NaNround=5 winds at a height of 10.6km (06.6miles). An established dry line over western Bangladesh served as a focal point for thunderstorm development. By 12:00 UTC, all the aforementioned factors served to produce severe thunderstorms across the country.
Around 12:30 UTC, a tornado touched down near Daulatpur in the Manikganj District and traveled east, soon striking Saturia. It caused tremendous damage across a 150km2 area covering three upazilas, with Saturia being hardest-hit.[8] Its path was about 80km (50miles) long.[9] A World Meteorological Organization news letter noted the tornado as F3 on the Fujita Scale. However, the stated wind estimate of 338to would rank it as an F4.[10] [11]
According to the World Meteorological Organization in 2017, the tornado killed roughly 1,300 people and injured 12,000. In 2022, this death toll was challenged in a paper authored by Dr. Fahim Sufi with the Australian Government, Dr. Edris Alam with the University of Chittagong, and Dr. Musleh Alsulami with the Umm al-Qura University, where it was stated the deadliest tornado in Bangladesh history was the 14 April 1969 Dhaka, Bangladesh tornado, which killed 922 people.[12] This new publication stills keeps a Bangladesh tornado as the deadliest in history, just not this specific tornado.[12] Damage was extensive, as countless trees were uprooted and every home within a six square kilometer area of the tornado's path was completely destroyed.[1] An article in the Bangladesh Observer stated, "The devastation was so complete, that barring some skeletons of trees, there were no signs of standing infrastructures".[1] Approximately 80,000 people were left homeless. A second tornado struck the Narsingdi District, killing 5 people and injuring 500 others.