A cloudburst is an extreme amount of precipitation in a short period of time, sometimes accompanied by hail and thunder, that is capable of creating flood conditions. A cloudburst can suddenly dump large amounts of water e.g. 25 mm of precipitation corresponds to 25000 metric tons/km2 (1 inch corresponds to 72,300 short tons over one square mile). However, cloudbursts are infrequent as they occur only via orographic lift or occasionally when a warm air parcel mixes with cooler air, resulting in sudden condensation. At times, a large amount of runoff from higher elevations is mistakenly conflated with a cloudburst. The term "cloudburst" arose from the notion that clouds were akin to water balloons and could burst, resulting in rapid precipitation. Though this idea has since been disproven, the term remains in use.
Rainfall rate equal to or greater than 100 mm (3.97 inches) per hour is a cloudburst. However, different definitions are used, e.g. the Swedish weather service SMHI defines the corresponding Swedish term "skyfall" as 1 mm/min for short bursts and 50 mm/h for longer rainfalls. The associated convective cloud can extend up to a height of 15 km above the ground.
During a cloudburst, more than 20 mm of rain may fall in a few minutes. The results of cloudbursts can be disastrous. Cloudbursts are also responsible for flash flood creation.
Rapid precipitation from cumulonimbus clouds is possible due to the Langmuir precipitation process precipitation process in which large droplets can grow rapidly by coagulating with smaller droplets which fall down slowly. It is not essential that cloudbursts occur only when a cloud clashes with a solid body like a mountain. They can also occur when hot water vapor mingles into the cold resulting in sudden condensation.
In the Indian subcontinent, a cloudburst usually occurs when a monsoon cloud drifts northwards, from the Bay of Bengal or Arabian Sea across the plains, then onto the Himalaya and bursts, bringing rainfall as high as 75 millimeters per hour.
In September, 2004 341 millimetres (13.4 in) mm of rain was recorded in Dhaka in 24 hours.
On June 11, 2007 425 millimetres (16.7 in) mm of rain fell in 24 hours in Chittagong.
On July 29, 2009 a record breaking 333 millimetres (13.1 in) of rain was recorded in Dhaka, in 24 hours, previously 326 millimetres (12.8 in) of rain was recorded on July 13, 1956.
On September 28, 1908 – A cloudburst resulted in a flood where the Musi River swelled up to 3.4 meters. About 15,000 people were killed and around 80,000 houses were destroyed along the banks of the river.
In July 1970, a cloudburst in the upper catchment area led to a 15-metre rise in the Alaknanda River in Uttarakhand. The entire river basin, from Hanumanchatti near the pilgrimage town of Badrinath to Haridwar was affected. An entire village was swept away.
On August 15, 1997, 1,500 people were killed when a cloudburst occurred and trail of death was all that was left behind in Chirgaon in Shimla district, Himachal Pradesh.
On August 17, 1998, a massive landslide following heavy rain and a cloudburst at Malpa village killed 250 people, including 60 Kailash Mansarovar pilgrims in Kali valley of the Pithoragarh district, Uttarakhand. Among the dead was Odissi dancer Protima Bedi.
On July 16, 2003, about 40 people were killed in flash floods caused by a cloudburst at Shilagarh in Gursa area of Kullu district, Himachal Pradesh.
On July 6, 2004, at least 17 people were killed and 28 injured when three vehicles were swept into the Alaknanda River by heavy landslides triggered by a cloudburst that left nearly 5,000 pilgrims stranded near Badrinath shrine area in Chamoli district, Uttarakhand.
On 26 July 2005, a cloudburst caused approximately 950 millimetres (37 in) of rainfall in Mumbai. over a span of eight to ten hours; the deluge completely paralysed India's largest city and financial centre, leaving over 1,000 dead. Half of the flooding was caused due to the blockage sewers in many parts of Mumbai.
On August 14, 2007, 52 people were confirmed dead when a severe cloudburst occurred in Bhavi village in Ganvi, Himachal Pradesh.
On August 7, 2009, 38 people were killed in a landslide resulting from a cloudburst in Nachni area near Munsiyari in Pithoragarh district of Uttarakhand.
On August 6, 2010, in Leh, a series of cloudbursts left over 1,000 people dead (updated number) and over 400 injured in the frontier Leh town of Ladakh region in Jammu and Kashmir.
On September 15, 2010, a cloudburst in Almora in Uttarakhand submerged two villages, one of them being Balta, in which save for a few people, the entire village drowned. Almora was declared as a town suffering from the brunt of cloudburst by the Uttarakhand authorities.
On September 29, 2010, a cloudburst in NDA (National Defence Academy), Khadakwasla, Pune, in Maharashtra left many injured and hundreds of vehicles and buildings damaged due to the consequent flash flood.
Again on October 4, 2010, a cloudburst in Pashan, Pune, in Maharashtra left 4 dead, many injured and hundreds of vehicles and buildings damaged; the record books registered the highest rainfall in intensity and quantity in Pune city, then about 118 years old (record of 149.1 mm in 24 hours)of October 24, 1892. In the history of IT hub Pune,for the first time this flash flood forced locals to remain in their vehicles, offices and what ever available shelter in the accompanying traffic jam.
On October 4, 2010, a cloudburst in Pashan, Pune may have been the world's first predicted cloudburst. Since 2:30 pm weather scientist Kirankumar Johare in the city frantically sent out SMSs to the higher authorities warning of an impending cloudburst over the Pashan area. Even after taking the necessary precautions, 4 people died including one young scientist.
On June 9, 2011, near Jammu, a cloudburst left four people dead and over several injured in Doda-Batote highway, 135 km from Jammu. Two restaurants and many shops were washed away
On 20 July 2011, a cloudburst in upper Manali, 18 km from Manali town in Himachal Pradesh state left 2 dead and 22 missing.
On September 15, 2011, a cloudburst was reported in the Palam area of the National Capital Territory of Delhi. The Indira Gandhi International Airport's Terminal-3 was flooded with water at the arrival due to the immense downpour. Even though no lives were lost in the rain that lasted an hour, it was enough to enter the record books as the highest rainfall in the city since 1959.
On September 14, 2012, there was a cloudburst in Ukhimath in the Rudraprayag district, Uttarakhand killing 39 people.
On June 15, 2013, a cloudburst was reported in Kedarnath and Rambara region of Rudraprayag district, Uttarakhand. Over 1,000 killed to date, it is feared that the death toll may rise to 5,000. Debris is still being cleared and thousands as still are still missing as of June 30, 2013. It left approximately 84,000 people stranded for several days. The Indian Army and its Northern Command launched one of the largest and most extensive human rescue missions in its history. Spread over 40,000 square kilometres, 45 helicopters were deployed to rescue the stranded. According to a news report this incident was falsely linked with cloud burst, rather it was caused due to disturbance in the two glaciers near Kedarnath.
On July 30, 2014, a landslide occurred in the small Indian village of Malin, located in Ambegaon taluka in Pune district of India. The landslide, which hit the village early in the morning while its residents were asleep,killed at least 20 people.In addition to those dead, over 160 people were believed to have been buried in the landslide in 44 separate houses,[4] though more recent estimates place the figure at about seventy
On July 31, 2014, a cloudburst was reported in Tehri Garhwal district of Uttarakhand. At least 4 people were reported dead. Search and rescue operations are underway.
On September 6, 2014 there was a cloudburst in Kashmir valley killing more than 200 people. Center for Science and Environment (CSE) mentioned heavy and unchecked development aggravated the development in the region. Over 1,84,000 people were rescued after heavy rains have large part of the State submerged.
On May 8, 2016 Continuous rainfall occurred in Tharali and Karnaprayag in Chamoli district, Uttarakhand resulting in damage, but no casualties.
On July 1, 1977, the city of Karachi was flooded when 207 millimetres (8.1 in) of rain was recorded in 24 hours.
On July 23, 2001 620 millimetres (24 in) of rainfall was recorded in 10 hours in Islamabad. It was the heaviest rainfall in 24 hours in Islamabad and at any locality in Pakistan during the past 100 years.
On July 23, 2001 335 millimetres (13.2 in) of rainfall was recorded in 10 hours in Rawalpindi.
On July 18, 2009, 245 millimetres (9.6 in) of rainfall occurred in just 4 hours in Karachi, which caused massive flooding in the metropolis city.
On July 29, 2010 a record breaking 280 millimetres (11 in) of rain was recorded in Risalpur in 24 hours.
On July 29, 2010 a record breaking 274 millimetres (10.8 in) of rain was recorded in Peshawar in 24 hours.
On August 9, 2011 176 millimetres (6.9 in) of rainfall was recorded in 3 hours in Islamabad flooded main streets.
On August 10, 2011 a record breaking 291 millimetres (11.5 in) of rainfall was recorded in 24 hours in Mithi, Sindh Pakistan.
On August 11, 2011 a record breaking 350 millimetres (14 in) of rainfall was recorded in 24 hours in Tando Ghulam Ali, Sindh Pakistan.
On September 7, 2011 a record breaking 312 millimetres (12.3 in) of rainfall was recorded in 24 hours in Diplo, Sindh Pakistan.
On September 9, 2012 Jacobabad received the heaviest rainfall in the last 100 years, and recorded 380 millimetres (15 in) in 24 hours, as a result over 150 houses collapsed.
