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Historic rainfall floods southeast India

More rain fell in 24 hours – in the city of Chennai, India – on December 1-2, 2015, than since 1901.

December 1 -2, 2015. Image credit: Joshua Stevens/NASA Earth Observatory

Satellite-based estimates of rainfall over southeastern India on December 1–2, accumulating in 30–minute intervals. The brightest shades on the maps represent rainfall totals approaching 400 millimeters (16 inches) during the 48-hour period. Image credit: Joshua Stevens/NASA Earth Observatory

India’s southeastern state of Tamil has seen a month of the heaviest rains in over a century, beginning November 12, 2015. In the massive flooding that has ensued, at least 250 people have died, several hundred have been critically injured, and thousands have been displaced. On December 1–2, 2015, the state capital city of Chennai received more rainfall in 24 hours than it had seen on any day since 1901.

In Chennai, which has a population of about 4.5 million people, the flooding has closed factories, turned of power, shut down the airpott and forced thousands of people out of their homes, reports the Huffington Post. In some parts of the state, people have been forced to walk through neck-deep water.

An Indian labourer pushes his cycle trishaw through floodwaters in Chennai on December 1, 2015, during a downpour of heavy rain in the southern Indian city.  Heavy rains pounded several parts of the southern Indian state of Tamil Nadu and inundating most areas of Chennai, severely disrupting flights, train and bus services and forcing the postponment of half-yearly school exams.   AFP PHOTO/STR / AFP / STRDEL        (Photo credit should read STRDEL/AFP/Getty Images)

An Indian laborer pushes his cycle trishaw through floodwaters in Chennai on December 1, 2015, during a downpour of heavy rain in the southern Indian city. Heavy rains pounded several parts of the southern Indian state of Tamil Nadu and inundating most areas of Chennai, severely disrupting flights, train and bus services and forcing the postponement of half-yearly school exams. Image credit: STRDEL/AFP/Getty Images

According to a NASA report, meteorologists attribute the rains to a super-charged northeast monsoon. In the winter, prevailing winds blow from northeast to southwest across the country, which tends to have a drying effect in most places, particularly inland. But those northeasterly winds also blow over the warm waters of the Bay of Bengal, where they evaporate a great deal of moisture from the sea and dump it over southern and eastern India. Coastal eastern India receives 50 to 60 percent of its yearly rainfall during this winter monsoon.

In 2015, this pattern was amplified by record-warm seas and by the long-distance effects of El Niño, says NASA. The city of Chennai recorded 1218.6 millimeters (47.98 inches) of rain in November 2015, according to Weather Underground blogger Bob Henson. India’s meteorological department noted that rainfall was 50 to 90 percent above normal in the eastern states. Then 345 millimeters (13.58 inches) more fell on Chennai in the December 1–2 storm, which was fueled by a low-pressure system offshore.

Indian rescue workers on a boat move people to safety amidst water-logged houses in a flooded suburb of Chennai on November 17, 2015.   India has deployed the army and air force to rescue flood-hit residents in the southern state of Tamil Nadu, where at least 71 people have died in around a week of torrential rains.  AFP PHOTO        (Photo credit should read STR/AFP/Getty Images)

Indian rescue workers on a boat move people to safety amidst water-logged houses in a flooded suburb of Chennai on November 17, 2015. India has deployed the army and air force to rescue flood-hit residents in the southern state of Tamil Nadu, where at least 71 people have died in around a week of torrential rains. Image credit: STR/AFP/Getty Images

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Bottom line: India’s southeastern state of Tamil has seen a month of the heaviest rains in over a century, beginning November 12, 2015. In the massive flooding that has ensued, at least 250 people have died, several hundred have been critically injured, and thousands have been displaced. On December 1–2, 2015, the state capital city of Chennai received more rainfall in 24 hours than it had seen on any day since 1901.

Read more from NASA’s Earth Observatory

Eleanor Imster

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