Thunderstorm tropical storms with thunder and lightning accompanied by heavy rain or hail. In hot, humid days warm wet air moves up into the sky and cools rapidly and produces dark thunderclouds. These storm clouds are usually 5 km wide and 8 km high. Usually an individual thunderstorm is just one "cell" in a group of storms which may be 30 km wide, lasting for more than five hours. A single cell storm can also become a super storm covering an area of 50 km. This produces large hailstones, strong winds, thunder and lightning.

In Bangladesh in early summer during March/April and late monsoon in October/November, this type of thunderstorm occurs in the evening with great intensity. This is popularly known as "Kal Baishaki" in the early summer and "Ashshiner Jhor" during late monsoon. [Naznin Afrose Huq]