Brace for heavy rain: IMD issues red alert, waterlogging warnings for South Bengal

This weather system developed at 5.30 am on Wednesday under the influence of an upper-air cyclonic circulation over the northwest Bay of Bengal and its adjoining areas. The IMD has forecast heavy to very heavy rainfall of about 7-20 cm, with isolated extremely heavy rainfall of more than 20 cm, over parts of South Bengal on Thursday.

South 24 Parganas and East Midnapore face the most severe threat, with a red alert for heavy to very heavy rainfall and isolated extremely heavy rainfall. On Thursday, the extreme rainfall risk moves westwards, with red alerts issued for parts of West Midnapore and Bankura. Several other districts remain under orange and yellow warnings during the period.

Kolkata to be cloudy

Kolkata, meanwhile, is likely to be under generally cloudy conditions with a few episodes of light to moderate rain or thundershowers and one or two intense spells over the next 24 hours. The maximum and minimum temperatures are expected to be around 32 and 27 degrees Celsius, respectively.

The city had recorded only 0.1 mm of rainfall in the last 24 hours till 6.30 am on Wednesday, while rainfall since 8.30 am on August 11 also stood at 0.1 mm. As per the midday update, rainfall recorded since 8:30 am on Wednesday was only a trace. The maximum temperature recorded was 32.6 and the minimum 27.9 degrees Celsius, while relative humidity touched 96 per cent during the day.

However, the weather system was already causing thunderstorms and intense rainfall across several parts of the state. A series of nowcast warnings issued by the Regional Meteorological Centre through Wednesday flagged thunderstorms, lightning, rain and gusty winds (~30-40 kmph) across districts including South 24 Parganas, East and West Midnapore, Howrah, Hooghly, Bankura, Purulia, Cooch Behar and Alipurduar.

Some of the alerts were updated to orange as rainfall intensified. An afternoon orange alert covered parts of Howrah, Hooghly, East Midnapore and West Midnapore, forecasting intense rain accompanied by gusty winds of about 30-40 kmph and the possibility of temporary waterlogging in low-lying areas. Orange alerts were also issued for parts of Bankura-Purulia and Cooch Behar-Alipurduar during the day.

The IMD has warned of waterlogging and temporary inundation in low-lying areas, damage to standing crops and horticulture, and possible damage to kutcha roads and vulnerable structures. Lightning strikes are also likely during thunderstorms.

North Bengal to see lighter rains

The warning pattern in North Bengal is discernibly less severe but more prolonged. Darjeeling and Kalimpong are expected to remain under yellow warnings through the week, while Jalpaiguri and Alipurduar face an orange alert on Friday for heavy to very heavy rainfall of about 7-20 cm at one or two places. Cooch Behar is also expected to remain under yellow warnings, with heavy rainfall risk persisting later in the forecast period.

North Dinajpur, South Dinajpur and Malda, meanwhile, are expected to see warnings ease after the initial part of the week. The broader forecast nevertheless remains wet, with light to moderate rain or thundershowers likely at many places during the first part of the forecast period and becoming more widespread later.

The current weather formation has also prompted a marine warning. Squally weather with winds of around 40-50 kmph gusting up to 60 kmph is expected along and off the West Bengal, Bangladesh and Odisha coasts and the North Bay of Bengal on Wednesday, increasing to about 50-60 kmph with gusts up to 70 kmph on Thursday. Fishermen have been advised against venturing into the sea from August 12 to 15. The IMD has also issued a swell surge alert, with waves of around 1.2-1.4 metres lasting for a period of 15-21 seconds expected through Thursday evening.

The IMD has advised people to remain in safe places during thunderstorms and avoid open fields, isolated trees, water bodies, electric poles and vulnerable structures.

Arghya Chakravorty is an intern with The Indian Express.