After a brief lull, south Bengal is likely to see another wet spell this week, though the rain is not expected to be heavy. Calcutta is likely to receive more than one spell of showers between now and Friday, a Met official said.
The city has already surpassed its quota of rain days this monsoon (days when some precipitation is recorded at Alipore). September began on a rainy note, but the past couple of days have largely been dry. On Tuesday, the city was cloudy for most of the day. “The pent-up heat is likely to team up with the moisture and cause some rain between Wednesday and Friday,” said the official.
A Met office bulletin issued on Tuesday listed four weather systems currently at play (over land and sea):
- The monsoon trough at mean sea level now passes through Pakistan, Jodhpur (Rajasthan), Barabanki (Uttar Pradesh), Chhapra (Bihar), Purulia, Digha, and then eastwards to the northeast Bay of Bengal.
- An upper-air cyclonic circulation lies over south Odisha and north coastal Andhra Pradesh.
- Another upper-air cyclonic circulation is present over east Bihar and the surrounding region, at around 3.1km above mean sea level.
- A trough in the westerlies lies at 1.5km above mean sea level, extending from Bihar to Bengal.
“Under the presence of the above meteorological conditions and strong moisture incursion, widespread light to moderate rainfall with isolated heavy to very heavy rainfall activity is very likely over... north Bengal,” the bulletin said.
The official said that while the monsoon trough does pass through south Bengal, it is not very strong. “The trough from Bihar to Bengal is the main catalyst that will inject a lot of moisture into the atmosphere. But most of it will go to north Bengal. The circulation will affect Odisha and Andhra.”
As a result, north Bengal’s Darjeeling, Kalimpong, Cooch Behar, North Dinajpur, Alipurduar, and Jalpaiguri are expected to receive heavy to very heavy rainfall. The wet spell is likely to continue till at least September 15.
In south Bengal, the rain is expected to be lighter, accompanied by streaks of lightning and mild gusts of wind.