Northeast monsoon dumps 57% excess rainfall in Tamil Nadu in 2021

2021 was a “good year” for Tamil Nadu, especially Chennai and its neighbouring districts, in terms of rainfall with the North-east Monsoon (NEM), the state’s lifeline, alone registering 57 per cent excess rains between October 1 and December 30.

Chennai received rains through the year, barring March, with November and December turning to be “most bountiful.” However, the sudden rains, which were heavy to extremely heavy on a few days including on December 30, plunged the city into chaos a couple of times during which faultlines in the rain infrastructure were exposed.

Data released by the Indian Meteorological Department (IMD) said Tamil Nadu received 701.88 mm of rainfall during the NEM season (October-December) against the normal rainfall of 447.1 mm.

Also read: Heavy rains force closure of government offices, educational institutes in Chennai, adjoining districts

“This is 59 per cent higher than the normal rainfall received during the NEM. Villupuram tops the list with 119 per cent excess rainfall during the season. As a whole, instead of 45 cm of rainfall, the state received 71 cm of rainfall,” the IMD said.

As far as Chennai is concerned, 2021 ended as the sixth-best year in terms of NEM rainfall with the city receiving 148.5 cm as against the normal amount of 80 cm. Weather blogger Pradeep John said with 210.8 cm rainfall, 2005 stands at the top for a 200 year period, 2015 (166.4 cm), 1888 (159.8 cm), 1946 (158.2 cm), and 1997 (157.1 cm), and 2021 (148.5 cm).

The bountiful rains have brought cheer to the people of Tamil Nadu as the majority of reservoirs have almost their full capacities. In Chennai, all the five reservoirs that supply drinking water to the city are full in a clear indication that there will be no water crisis during the Summer of 2022.

Also read: Sudden heavy rains drench Chennai; claim 3 lives

Not just the last three months of the year, 2021 has been a bountiful rain year for Chennai with rains lashing the city every month, barring March, sparing a water crisis this time around. The city achieved the monthly average for November during the North-east Monsoon (NEM) in the first eight days of the month. While the average rainfall for November is 37.4 cm, the rainfall received from November 1 to 8 is 41.5 cm, data available with the IMD said.

K Srikanth, a weather blogger, told DH the pattern of the monsoon itself is changing as the number of rainy days could be lesser but the spells will be heavier.

On the extreme rainfall on December 30, Srikanth said the sudden change in direction of winds at 5.5 km ASL off the coast of Chennai enhanced the lower level of moisture brought in from the Bay.

“We have seen in the past interplay between lower-level Easterly winds & upper-level Westerly winds provide for Mid-Level Shear that enhances thunderstorms. Yesterday was possibly another instance of such interactions providing conducive conditions,” Srikanth said.

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