The Hindu Business Line
Monsoon will withdraw in third week of October, says expert from Germany
A string of low-pressure areas, with at least one going on to become a depression, will send the monsoon to a rare peak in the last week of this month, that is co-terminus with the end of the season as well.
The first of these ‘lows’ may spring up ‘any time’ over the West-Central Bay of Bengal and adjoining Coastal Andhra Pradesh, India Met Department (IMD) said on Wednesday afternoon.
String of ‘low’s
The second ‘low’ is forecast to materialise over the East-Central and adjoining North-East Arabian Sea, North Konkan, and South Gujarat by Friday, and it could go on to become a monsoon depression.
The Climate Prediction Centre of the US National Service predicts that the entire Gujarat, Saurashtra and Kutch regions slipping under heavy rainfall over the next few days, even as the depression heads out for Oman. A third ‘low’ is forecast to develop over the East-Central Bay by September 24 (next Tuesday) bringing heavy rain to East-Central India, the East Coast and adjoining South Peninsula, the IMD said.
In fact, its wind profile projections suggested that the first ‘low’ brewing over the Bay would guide itself across Peninsular India and enter the Arabian Sea to set up the depression.
But the system developing later in the Bay would be an ‘in situ’ product, though monsoon easterlies from the NorthWest Pacific/South China Sea are seen lending it incremental support.
This ‘low’ would force some delayed, but welcome, rains into the variously parched areas of Bengal, Jharkhand and Bihar, according to available forecasts.
Strong monsoon signs
Other signs of a strong monsoon include an East-to-West trough running from Saurashtra to the East-Central Bay of Bengal across the northern parts of Peninsular India. Additionally, an East-to-West shear zone of monsoon turbulence runs across the South Peninsula (Interior Karnataka and Andhra Pradesh) where the ‘low’s or depression flourish.
Combined with the prospect of the incoming ‘low’ from the Bay getting incorporated into this ecosystem, the shear zone is likely to persist during the next two to three days, and boost the rainfall for as long.
An IMD update said that widespread rainfall with isolated heavy to very heavy and extremely heavy falls were recorded over Andhra Pradesh and Telangana on Tuesday.
Going forward, it has forecast fairly widespread to widespread rainfall with isolated heavy to very heavy falls over Coastal Andhra Pradesh, Telangana and Rayalaseema until Thursday.
A similar forecast is valid for Konkan, Goa, Madhya Maharashtra and Vidarbha mainly between Wednesday and Friday with extremely heavy falls being forecast over the Ghat areas.
Affected areas in this manner will include Madhya Maharashtra on Thursday, and North Konkan on both Thursday and Friday, an IMD warning issued on Wednesday said. The southwest monsoon is likely to withdraw from the central parts of India between October 14 and 24, extending the four-month rainy season further, a senior scientist at a renowned climate research institute in Germany has said.
Elena Surovyatkina, a physicist working on weather modelling at the Potsdam Institute for Climate Impact Research (PIK) in Germany, said the withdrawal of monsoon this year is expected to be in the third week of October.
Extended monsoon days
The season got extended because of very high temperatures on the periphery of monsoon in Pakistan and Afghanistan, said Surovyatkina, who was here this week to participate in a workshop on East Africa Peru India Climate Capacities (EPICC) that PIK organised together with the The Energy and Resources Institute and other institutions.
Even though the monsoon normally begins to withdraw from North-Western parts of the country from September 1, it has not happened so far.
Her team, she said, has been reliably forecasting the monsoon withdrawal from India since 2016. “This time we have forecast it around 70 days in advance,” Surovyatkina, who leads a group on Indian monsoon forecasting at EPICC, told BusinessLine.
She claimed that the PIK forecast was the only longterm forecast available for withdrawal of monsoon in India. “The monsoon withdrawal date is of crucial importance for a billion people in India. In a warming world, severe storms and floods during monsoon retreat are becoming more frequent. Such a long-term forecast could help the government to do strategic planning, consolidate resources, and strengthen capacity to respond effectively to disasters,” she said.
This year, she said, heavy monsoon rains have triggered flooding in central and northern parts of India, Pakistan, Bangladesh and Nepal, leaving numerous casualties, tens of thousands displaced and millions affected. National Disaster Response Forces are working round-the-clock, conducting rescue operations, helping children and carrying the elderly out of flooded houses, the scientist said.
The summer monsoon rainfall is the most important source of water in India. About 80 per cent of the river flow occurs during the four to five months of the summer monsoon season. India collects and stores rainwater in dams in monsoon seasons to sustain themselves in the dry season. In particular, hydroelectric power plants are driven by water collected during the monsoons.
“This is why at the end of monsoon season the main goal is to save as much water as possible. The release of dam water during that period is sharply criticised, because it’s a waste of the most valuable resource. However, when dams are full and heavy rains come, it can trigger dams spilling and floods with catastrophic consequences,” Surovyatkina said.