cyclone

1. 1991 Bangladesh cyclone
Super Cyclonic Storm BOB 01
Super cyclonic storm (IMD)
Category 5 tropical cyclone (SSHS)
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.
Formed April 24, 1991
Dissipated April 30, 1991
3-minute sustained:
Highest 240 km/h (150 mph)
winds 1-minute sustained:
260 km/h (160 mph)
Lowest pressure 918 mbar (hPa; 27.11 inHg)
Fatalities 138,866 total
Damage $1.7 billion (1991 USD)
Areas
Bangladesh
affected
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.

2. [edit] Meteorological history
Storm path
An area of persistent cloudiness, in part due to the monsoon trough, developed into a tropical
depression on April 22 in the Bay of Bengal. The wind speed and overall size increased, with the
depression becoming Tropical Storm 02B on the 24th. The enormous wind field at the time
encompassed nearly the entire 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 a 160 mph Cyclone, 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 Category 4 Cyclone. The storm rapidly weakened over land, and dissipated on the 30th
over southeast Asia.
[edit] Impact
[edit] Fatalities
Flooding around a river in Bangladesh
At least 138,000 people were killed by the storm,[1] with the majority of deaths in the Chittagong
area. 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.
[edit] Property damage
A damaged village in Bangladesh, surrounded by flooded fields, three weeks after the storm had
struck

3. The storm caused an estimated $1.5 billion (1991 US dollars) in damage. The high velocity wind
and the storm surge devastated the coastline. Although a concrete levee was in place near the
mouth of the Karnaphuli River in Patenga, it was washed away by the storm surge. The cyclone
uprooted a 100-ton crane from the Port of Chittagong, and smashed it on the Karnaphuli River
Bridge, effectively breaking it into two partitions. A large number of boats and smaller ships ran
aground. Bangladesh Navy and Bangladesh Air Force, both of which had bases in Chittagong,
were also heavily hit. The Isha Khan Naval Base at Patenga was flooded, with heavy damages to
the ships. Most of the fighter planes belonging to the air force were damaged. Approximately
1 million homes were destroyed, leaving about 10 million people (a substantial portion of
Bangladesh's population) homeless.
[edit] Environmental impact
The storm surge subsequently caused the embankment, as well as whole villages, to be swept
away. For an additional three to four weeks after the storm had dissipated, mass land erosion
resulted in more and more farmers losing their land, and therefore, the number of unemployed
rose.[2]
[edit] International response
Bangladeshis unloading international aid from a US helicopter
The United States amphibious task-force, consisting of 15 ships and 2,500 men, returning to the
US after the Gulf War was diverted to the Bay of Bengal. This was part of Operation Sea Angel,
one of the largest military disaster relief efforts ever carried out, with the United Kingdom,
China, India, Pakistan and Japan also participating.[1]
Operation Sea Angel began on May 10, 1991 when President Bush directed the US military to
provide humanitarian assistance. A Contingency Joint Task Force under the command of
Lieutenant General Henry C. Stackpole, consisting of over 7,000 US soldiers, was subsequently
sent to Bangladesh to provide food, water, and medical care to nearly two million people. The
efforts of U.S. troops, which included 3,000 tons of supplies, are credited with having saved as
many as 200,000 lives.[3]