Monsoon rainfall below usual, likely to surge in late July

From 21 July, heavy rainfall is likely in Sylhet, Cox’s Bazar, Chattogram, and Mymensingh divisions, BMD says

In the ongoing monsoon, the country has received less rainfall than usual so far. However, heavy rainfall is likely in many parts of the country in the last 10 days of July, according to Bangladesh Meteorological Department (BMD).

As of the first 13 days of July, the average rainfall was 133 mm, which is 39% less than usual, according to BMD data. The normal rainfall in the country for July is 523 millimetres (mm).

Weather experts said this year, the country has broken all previous records for heatwaves and may also exceed rainfall records.

They said due to climate change and the impact of monsoon winds, many areas in the country witnessed less rainfall than normal despite it being the rainy season. However, some areas have already recorded more than double the usual rainfall.

In June, Sylhet recorded more than 2000mm of rainfall, nearly two and a half times the normal amount of 818mm. In July, the normal rainfall in Sylhet is 819mm. However, within just 13 days of July, the district witnessed 614 mm of rainfall.

A K M Nazmul Haque, meteorologist at BMD, told The Business Standard that rainfall in the first 10 days of July was normal in most areas except for 2-3 regions. But, after 20 July, rainfall is likely to increase nationwide and higher-than-normal levels are likely in the last 10 days.

The meteorologist also said due to climate change, the trend of rainfall has changed somewhat in the country, leading to more intense downpours over short periods.

Light rainfall will continue in Khulna, Rajshahi, and Dhaka until 20 July. From 21 July, heavy rainfall is expected in Sylhet, Cox’s Bazar, Chattogram, and Mymensingh divisions, he added.

According to rainfall data from BMD and Flood Forecasting and Warning Centre (FFWC), in Dhaka, the normal rainfall is 373mm in July, but 285mm have already been recorded in the last 13 days.

On Sunday, the highest rainfall in the country was recorded in Tentulia at 86mm, while Dhaka recorded 5mm of rainfall.

In 13 days of July, rainfall records show 880mm in Teknaf, 898mm in Cox’s Bazar, and 1235mm in Sunamganj. In contrast, the normal rainfall for these areas in July is 1030, 925, and 1403mm respectively.

According to the flood warning centre, water levels at 13 stations are above the danger level, with the Dudhkumar River rising by 7cm.

Sarder Udoy Raihan, executive engineer at FFWC, said the Brahmaputra, Jamuna, Dudhkumar, Atrai, Surma, Kushiyara, and Someswari Rivers are above danger levels. The Brahmaputra-Jamuna Rivers are currently falling, the trend may continue for the next 72 hours. Flood conditions in the northeastern low-lying areas may improve in the next 48 hours.

The BMD’s bulletin forecasted moderately heavy falls at places over the Rangpur, Mymensingh, Chattogram, and Sylhet divisions.