Monsoon revival in Maharashtra: What has caused heavy rains and how long will they continue for?

What has led to the revival of showers?

Meteorologists have linked the upcoming spell of showers to weather systems, specifically upper air cyclonic circulation and troughs. According to the weather bureau, there is currently an upper air cyclonic circulation system over the central Bay of Bengal, off the north coast of Andhra Pradesh. Another upper air cyclonic system that was over Marathwada is now positioned over south central Maharashtra.

Meanwhile, monsoon troughs have also developed above these systems. For perspective, the monsoon trough is an elongated low-pressure area which extends from the heat low over Pakistan to the Bay of Bengal. It is a semi-permanent feature of monsoon circulation, and its southward movement results in heavy downpours. Meanwhile, a cyclonic circulation is an atmospheric wind flow in the upper levels associated with any low-pressure system.

For Mumbai, systems such as troughs and low-pressure systems are crucial in ushering in heavy showers during the monsoon period.

For how long will heavy rain continue in the region?

According to the weather bureau, rainfall activity across Maharashtra is expected to persist until at least June 18. Meanwhile, the Konkan region will experience heavy to very heavy rainfall until at least June 16 (Monday).

Ratnagiri and Raigad districts are expected to experience heavy rainfall until Thursday, prompting an orange alert. According to the IMD forecast, Mumbai is expected to experience heavy rainfall until Tuesday morning. After that, no alerts will be issued, as only moderate rainfall is anticipated.

Independent weather forecasters like Athreya Shetty predict another wet spell next weekend.

“Presently, the cyclonic circulation is over north Ratnagiri and has embedded into a sheer zone, which is an area where opposing winds interact with the westerly winds above the sheer zone and easterly winds below it. The heavy showers across Maharashtra are a result of this system. The system’s effect is expected to intensify in Mumbai until Monday. After this, the rains will subside. But there will be another surge in showers by next week,” said Shetty.

How much rain does Mumbai experience in June?

This year, Mumbai experienced its earliest monsoon onset in 75 years on May 26, while the city typically sees the arrival of the southwest monsoon around June 11. Generally, Mumbai receives approximately 537 mm of rain in June.

In total, the city records about 2,319 mm of rainfall over the four monsoon months, from June to September, with July being the wettest month. This year, the city received over 500 mm of rain in May, which is more than 3,000 per cent above the normal levels.