The western districts have stolen Calcutta’s thunder this year, reversing a monsoon trend and leaving the city with a rain deficit that will be hard to make up with another month almost gone.
Burdwan, Bankura and Purulia have apparently benefited from a change in the pattern of monsoon wind systems, receiving more rain than they do in a normal year.
“Usually, the eastern parts of south Bengal like Calcutta, the two Parganas, Nadia and Murshidabad get more rain than the western districts of Burdwan, Bankura and Purulia. The situation has reversed this year with wind systems playing truant as far as the city is concerned,” said Gokul Chandra Debnath, director of the Regional Meteorological Centre in Alipore.
The city’s rain deficiency was 38.5 per cent in June and 38.2 per cent in July. August has been the worst so far with the shortfall touching 46 per cent, raising the overall monsoon deficit to 39 per cent.
In contrast, the western parts of south Bengal, closer to Odisha, are on the comeback trail after being heavily rain deficient till mid-July (see chart).
Burdwan, which has received the most rainfall among the western districts, has erased its deficit and currently stands at plus-15 per cent. Purulia, which had a 20 per cent deficit until a couple of weeks ago, has since risen to minus-1 per cent.
In the city, the skies have been overcast for long periods, albeit with little rain. The downpour last Thursday evening was like a popcorn break between two halves of a frustratingly long and boring movie.
“I don’t remember a long, heavy spell of rain this entire season. We have had to remain content with dark skies. Sometimes, the rain comes with a bang and goes before you can shut the window. What kind of weather is this?” said Garia homemaker Ranita Mitra.
In June, the highest rainfall in 24 hours was 34mm in the wake of the arrival of monsoon, which hit town 10 days behind schedule.
July saw a maximum of 26.2mm of rain in a day, while the highest in August so far has been 37.6mm.
Weather scientist Debnath blamed fewer low-pressure formations over the Bangladesh coast for the rain shortage.
“Being closer to the Bay of Bengal, there is more moisture accumulation over Calcutta and the other eastern districts than the western parts. One of the main reasons for such moisture incursion is the formation of low-pressure areas on the Bangladesh coast. This year, there were few of them. The ones that formed were too weak or moved west,” he said.
That is why more heavy, rain-bearing clouds have been forming over places like Burdwan, which are closer to the Odisha border. Calcutta has had to be content with smart showers.
Rainfall activity has subsided in the northern districts too after a surplus at the start of the season. But Darjeeling and Jalpaiguri are likely to receive heavy rainfall in the next 48 hours.
For Calcutta, the weather gods seem to have ordered a status quo.
Satellite pictures show no favourable wind systems that can bring rain to the city “at least in the next three days”, a weather scientist said.