A depression brewing over the Bay promises to reduce Calcutta’s record-breaking hot spell with light rain and clouding during the weekend.
Until then, brace for a sultry Thursday and Friday.
Satellite images and meteorological coordinates showed the depression at a location 600km south of Calcutta on Wednesday morning. It has a northerly trajectory but weather experts said the system would change path midcourse and steer away from Calcutta. Landfall and downpour is expected in Myanmar and parts of Bangladesh.
The city will get a bit of cloud cover and light rain during the weekend from the wind escaping the main mass of the depression.
“The depression is currently in east-central Bay of Bengal and travelling north. It is expected to grow stronger and become a deep depression by Thursday. It will adopt a north-northeastern trajectory over the next 24 hours and move away from the city,” said Devendra Pradhan, deputy director general of meteorology at the India Meteorological Department in Calcutta.
Clouds on the “spiral bands” or the outer rings of the system would possibly bring rain in Calcutta, he added.
Coastal Bengal could get moderate to heavy rain because of its proximity to the depression’s eye.
Experts said they have predicted the depression’s course change after calculating various parameters such as wind speed and direction.
Calcutta has not received a drop of rain since three days of shower from May 3 to 5 after a rainless April. Inland rain-bearers like Nor’westers have deceived the city this summer.
Wisps of cloud appeared over Calcutta on Wednesday and the maximum temperature came down overnight by 1.5 degrees Celsius to reach 40 degrees, though the depression was far away.
The Celsius was still five notches above normal as the nagging heatwave entered its 10th day. The minimum relative humidity that measures the sweat factor remained comparatively low on Wednesday at 34 per cent.
“Moisture incursion on the back of the depression would raise the humidity level on Thursday. The discomfort level would rise from Wednesday’s 64 per cent, which was 10 notches above the comfort zone,” an expert said.
Clouding will bring down the temperature on Friday but the weather is expected to remain sultry.
“The maximum temperature will touch 39 to 40 degrees Celsius on Thursday but it may fall thereafter as the depression moves closer to land,” said Ganesh Kumar Das, meteorologist at IMD, Calcutta.