Monsoon revival sees rise in extreme rainfall events

Konkan coast has seen 29% more rain than normal while central and northeast India have seen a deficit

Rainfall amid the monsoon’s revival since the second week of July has seen significant variation across the country.

Several parts of the western Konkan coast and the southern peninsula were seeing instances of extreme rainfall. According to the India Meteorological Department data on the regional distribution, the ‘South Peninsula’ has seen 29% more rain than normal for the period from June1-July 23.

For the same duration, northwest and central India have seen a 10% and 2% deficit respectively and the northeast India a 14% deficit, though this region has a higher base rainfall than other regions.

Mahabaleshwar in western Maharashtra reported over 60cm of rainfall in the last 24 hours (Thursday morning to Friday morning) which “exceeded its all-time record” according to the IMD. From Friday morning to 5.30 p.m., it recorded 18 cm.

On Friday, the agency said the torrential rains over the Konkan coast was likely to continue for the rest of the week due to the position of the monsoon trough.

“Fairly widespread to widespread rainfall with isolated heavy to very heavy falls very likely to continue over west coast during next 2-3 days with reduction thereafter. Isolated extremely heavy falls also very likely over Konkan and Goa and adjoining Ghat areas of Madhya Maharashtra during July 23-24, with a reduction thereafter and over coastal and south interior Karnataka,” said a Friday evening update from the agency.

According to the IMD’s district rainfall data for Maharashtra, except for five districts, all the other 31 got “large excess rains”.

July and August are the most important monsoon months contributing over two-third of the seasonal rainfall and central India as well as the south Peninsula are expected to see most of the rainfall during this interim. However, climate scientists have warned that monsoon patterns, overall have been changing.

The frequency and strength of cyclones over the Arabian Sea has increased in the last two decades. There is a 52% increase in the frequency of cyclones over Arabian Sea from 2001-2019 and 8% decrease over Bay of Bengal compared to 1982-2002, when historically most cyclones have been in Bay of Bengal, according to a study published this month in Climate Dynamics. Even the duration of these cyclones has increased by 80%. More cyclones were bringing in more moisture from the Arabian Sea and contributing to extreme rainfall events.

Roxy Koll, climate scientist at the Indian Institute of Tropical Meteorology in Pune and among the authors of that study tweeted that it was important to monitor and better forecast these events. “The ongoing monsoon floods across India is unprecedented, but not unexpected. We already see a threshold rise in widespread extreme rains that cause floods across India,” he said.

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