MAKING WAVES: A girl on her way to school is delighted at the water her car wheels are ploughing through on Friday morning. Picture by Amit Datta

Several spells of rain lashed Calcutta and its adjoining areas on Friday. The Met office predicted more showers in the next 24 hours.

“The monsoon over Gangetic Bengal is active and we expect rain at many places in Calcutta and the rest of south Bengal on Saturday. There is also a possibility of heavy rain at one or two places in south Bengal,” said G.C. Basu, the director at Regional Meteorological Centre, Alipore.

Two low-pressure, or monsoon, troughs over the state have been sucking in moisture from the Bay of Bengal.

One trough extends from Bihar to the east-central Bay of Bengal, across Jharkhand, Gangetic Bengal, Bangladesh and north Bay of Bengal. The other runs from Uttar Pradesh to sub-Himalayan West Bengal, across Bihar and Assam.

Met officials explained that the trough over Gangetic Bengal has moved eastward, causing the wet spells on Friday. “It is showing signs of moving away from Calcutta. The weather in the city may improve slightly on Saturday,” an official said.

The north Bengal districts, too, have been receiving heavy rain for the past three days because of the other trough. “There will be rain or thundershower in north Bengal, with a few spells of heavy rain in isolated places,” the official added.

Experts in the Met office pointed to another factor that has strengthened the monsoon troughs.

“Earlier this week, a low-pressure had formed over the Bay and passed across Gangetic Bengal to Jharkhand and Uttar Pradesh. The system had left a lot of moisture in the Bengal sky, strengthening the monsoon activity,” an official explained.