Climate Change

Northeast Monsoon gets good start due to low pressure system in Arabian Sea

The system has brought heavy rainfall to Kerala and north Karnataka, with more rain predicted

By Akshit Sangomla
Published: Monday 21 October 2019
A satellite image of Peninsular India showing the Northeast Monsoon. Photo: Hrishi Jawahar @jhrishi2/Twitter

The North East Monsoon (NEM) season which began alongside the end of the South West Monsoon season’s hasty withdrawal on October 16, 2019, has got off to a good start, courtesy a low-pressure system in the Arabian Sea. 

The low-pressure system in the Arabian Sea will intensify into a depression in the next two days and move towards the Indian Subcontinent before taking a turn towards the coast of Oman.

Last year, the NEM had a weak beginning and had stalled in the middle, with 26 Indian states and union territories receiving no rainfall between November 22 and 28, 2018, and ended with a country- wide deficit of 44 per cent.

Usually responsible for 48 per cent of the annual rainfall in Tamil Nadu and Puducherry, NEM also brings significant amount of rainfall to coastal Andhra Pradesh, Rayalaseema, Kerala, southern Karnataka and moderate rain to the rest of the southern peninsula.

The low-pressure system has brought extremely heavy rain to Kerala since October 20. It has also caught the India Meteorological Department (IMD) by surprise.

IMD issued its Red Alert (‘Take action’) forecast for extremely heavy rainfall only after rains had already drenched many of the districts. On the afternoon of October 20, IMD had issued an Orange Alert (‘Be prepared’) for the seven districts of Thiruvananthapuram, Alappuzha, Kottayam, Ernakulam, Idukki, Palakkad and Malappuram.

Only after 24 hours, IMD changed its alert to red for six of the districts — Thiruvananthapuram, Alappuzha, Kottayam, Ernakulam, Idukki and Palakkad. While the orange alert of Malappuram was not changed, Thrissur was put on red alert.

Thrissur district, which is home to more than 30 lakh people, had received a Green Alert (‘No warning’) on the previous day. Hence, no preparations would have been made by the authorities.

In the 24 hours from 8:30 am on October 20 to 8:30 am on October 21, Alappuzha received 173.4 millimetres (mm) of rainfall while Ernakulam received 160.4 mm rainfall. The ongoing by-poll elections in Ernakulam have been disrupted by the inundation caused by the rain.

IMD has also issued a red alert for extremely heavy rainfall on October 22 for five districts. While the red alert for Thiruvananthapuram has been brought down to Yellow (‘Be updated’), for Alappuzha and Kottayam, the alert has been changed to orange. Malappuram’s orange alert has been upgraded to red for October 22.

IMD has predicted heavy rainfall in other regions of the southern peninsula as well. Heavy rains in north Karnataka have already led to floods in the region which has not fully recovered from the floods in August in which 80 people had died.

On October 20 the districts of Dharwad and Haveri received 1,363 and 1,290 per cent more rainfall than normal respectively.

Another low-pressure area that will form in the Bay of Bengal on October 23, will bring heavy rainfall to Tamil Nadu, Puducherry and Andhra Pradesh in the next few days.

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