If a cyclone is moving away from the mainland, it drives the moisture away. But if it is progressing towards the coast, it could enhance the monsoon
The monsoon arrived in Kerala on June 8, 2023. It was eight days later than expected. Cyclone Biporjoy, which developed over the Arabian Sea on June 7, has influenced the progress.
This is because westerly winds, which pull the monsoon towards the Indian mainland, are weak now. All the moisture is rotating around the cyclone, according to Mahesh Palawat, vice president of Meteorology & Climate Change at Skymet Weather Services Pvt Ltd.
Rainfall will be weak over peninsular India and several parts of the country as a result of this.
When the onset of cyclones and monsoons coincides, they impact each other. “A cyclone cannot form if we have a strong monsoon,” according to Roxy Mathew Koll, a climate scientist at the Indian Institute of Tropical Meteorology (IITM).
If the southwest monsoon current is strong, winds blow in two directions — southwest in lower levels and northeast in upper levels of the atmosphere. This prevents the cyclone from rising vertically, hindering its formation.
This time the monsoon is weak, allowing the cyclone to develop vertically as it can pass through the winds and move upwards. While the reason for the weak monsoon could be the El Nino, it cannot be cited as the deciding factor.
El Nino is the warm phase of a recurring climate pattern across the tropical Pacific. Indian Ocean warming due to climate change could also be playing a role.
As for the cyclone, if it is moving away from the mainland, it drives the moisture away. But if it is progressing towards the coast, it could enhance the monsoon.
The progression of the monsoon this year could be weak till the cyclone fades away. This is because it is driving the monsoon winds towards Pakistan. It could get stronger thereafter.
For instance, Cyclone Nisarga helped the progression of the monsoon since it moved towards the subcontinent along with the monsoon. However, not all experts coincide with this view.
Akshay Deoras, a Research Scientist at the National Centre for Atmospheric Science and the Department of Meteorology, University of Reading disagrees, since the IMD has predicted that the monsoon will advance towards Karnataka, Tamil Nadu and the Northeast in the next couple of days.
The La Nina persisted for three years before ending in 2023. There is a 60 per cent chance for an El Nino during May-July 2023, according to the World Meteorological Organization.
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