Nor'wester count in April dips to 43-year low. What's the reason?

Usually, the Bengali month of Baisakh and the nor’wester, which is locally familiar as Kalbaisakhi, go hand in hand. 

The Bengali month started in the middle of April, the ongoing month of the Gregorian calendar, and half of its days have already passed. But only a single nor’wester has taken place so far across the country. 

Meteorologists, who generally describe the nor’wester as thunderstorm, said Bangladesh usually witnesses the highest number of thunderstorms in May, followed by June, September, and April, respectively. 

But the situation is quite different this April. Even, the geographical location of this season’s lone nor’wester is quite unusual as per records as it occurred in the southern part of the country. 

The scenario was obtained analysing the thunderstorm data preserved by the meteorological department. Meteorologists and climate experts have described the current weather pattern as abnormal. 

Thunderstorms occur in the country during the March-September period. Regarding the storms, Samarendra Karmakar, former director of the meteorological department, said all nor’westers are thunderstorms, but it is not vice versa. 

The meteorologist explained that storms that take place from March to May are actually regarded as nor’wester. As the wind flows from the west and causes storms and rain during the period, these storms are called nor’wester. 

The month of April usually remains very hot. The environment turns cool to some extent following thunderstorms and returns to the previous level afterwards. Thus, thunderstorms ensure a balance in the weather. 

But the current scenario is in stark contrast as the ongoing month experienced the longest heat wave in the history of 76 years. The ongoing spell of heat wave began on 1 April and continues till date. 

Umar Faruk, a meteorologist at the met office, carried out an analysis on the weather data since 1948. He told Prothom Alo that there was no instance of such a long heat wave in the previous 76 years.   

Another meteorologist, Abul Kalam Mallik, is doing research on weather and climate. Citing data from 1981 to April this year, he showed that there were 43 thunderstorms in total in April throughout the last 43 years. Of them, the year of 1997 witnessed the highest 14 thunderstorms in April, followed by nine in 2022, eight in 2021, seven in 2023, four in 1999 and 2009 each, and one in ongoing 2024. 

Meteorologists have attributed the decline in thunderstorms to the prevailing heatwave, exacerbated by global warming. 

Professor AKM Saiful Islam, director of the Institute of Water and Flood Management at BUET, underscored the impact of rising global temperatures on weather patterns. 

He pointed out that the global temperature has increased by 1.3 degrees Celsius, and it rose to a 122-year high in India this month. The current of this region has a relation with that of the bordering Indian states, including West Bengal, Bihar and Odisha. 

The current of this region has a relation with that of the bordering Indian states, including West Bengal, Bihar and Odisha. During this season, the water vapor coming from the sea of the bordering states creates thunderclouds. 

But the scenario is quite different this year as the Indian regions have been experiencing severe heat, which hindered the formation of thunderclouds, he said, adding it eventually led to less storms throughout the region.