75pc of rainfall recorded in just 11 Days

The amount of rainfall recorded in the first 11 days of July has already reached 75 per cent of the month's average rainfall.

Meteorologists say the unusually heavy rain has been caused by a combination of factors, including a low-pressure system, an active monsoon, unusual wind patterns, and the counteracting effects of El Niño.

The Bangladesh Meteorological Department (BMD) has forecast heavy to very heavy rainfall in different parts of the country again on Monday.

Continuous rainfall has already triggered flooding in several areas. The Flood Forecasting and Warning Centre has warned that flood situations may develop in at least 10 districts on Monday and Tuesday.

Rain has been falling across various parts of the country for more than a week. Heavy rainfall was recorded in many areas, including the capital, on Sunday.

According to the latest data, the highest rainfall in the country over the past 24 hours—from 6:00 pm Saturday to 6:00 pm Sunday—was recorded in Dhaka, where 175 millimetres of rain fell. It was the highest 24-hour rainfall recorded in the capital so far this month.

Bangladesh received at least 30 per cent less rainfall than normal in June. However, the BMD's long-range forecast issued at the beginning of July had predicted normal rainfall for the month.

July is typically the wettest month of the year in Bangladesh, with an average rainfall of 523 millimetres. This is considered the month's normal rainfall level.

A low-pressure system formed over the Bay of Bengal at the beginning of July, triggering widespread rainfall. The rain that began on 5 July had a particularly strong impact on various parts of the Chattogram Division.

Speaking to Prothom Alo on Sunday, meteorologist Md Hafizur Rahman said that continuous rainfall has persisted for more than a week. He noted that 75 per cent of July's average rainfall had already been recorded within the first 11 days of the month.

Meteorologists say that, in addition to the low-pressure system, the unusually active monsoon has been another major reason for the heavy rainfall. This year's monsoon arrived at least seven days later than usual. Although rainfall was below normal in June, the monsoon became highly active at the beginning of July, leading to the recent downpours.

Meteorologist Md Bazlur Rashid identified two additional factors behind the prolonged rainfall.

According to him, one reason is the unusual movement of the low-pressure system over the Bay of Bengal. Normally, such systems move through the southwestern regions of Khulna and Barishal before crossing the central Dhaka Division. This time, however, the moisture-laden air mass shifted toward the southeastern region, particularly the Chattogram Division, resulting in heavier rainfall there.

Earlier this year, the World Meteorological Organization (WMO) warned that the summer could be exceptionally hot due to the influence of El Niño. El Niño is a climate pattern associated with warming in the Pacific Ocean and often leads to higher global temperatures.

Much of Europe has experienced temperatures significantly above normal this year, and similar conditions have been observed in parts of North America.

Bazlur Rashid explained that El Niño can also produce an opposite effect: intense rainfall over short periods. While such rainfall may temporarily reduce heat, it often contributes to higher temperatures over the longer term. He said the current spell of heavy rain could be viewed as one of El Niño's counteracting effects.

At around 12:00 pm on Sunday, the Bangladesh Meteorological Department issued a warning of heavy to very heavy rainfall in six divisions over the following 24 hours. These divisions are Rangpur, Rajshahi, Mymensingh, Dhaka, Chattogram and Sylhet.

Meteorologist AKM Nazmul Haque told Prothom Alo that relatively heavy rainfall is likely in several districts of northern and northeastern Bangladesh on Monday. These include districts in the Rajshahi, Rangpur, Lalmonirhat, Mymensingh and Sylhet regions.

Rain is also expected in the capital, Dhaka. According to the meteorologist, the rainfall trend may begin to weaken from Tuesday.