Patterns of Daily Rainfall in Bangladesh During the Summer Monsoon Season: Case Studies at Three Stations

Abstract

Results of the statistical analyses of daily rainfall at 19 weather stations in Bangladesh, for the months of May through October, for the 35-yr. period 1964-1998 are presented in this paper. Emphasis has been given to the patterns of daily rainfall during the wettest and driest summer monsoon seasons at three stations. The summer monsoon in Bangladesh prevails from early June to mid-October, with an average duration of 110 days in the west to 134 days in the southeast, and an average number of rain days of 60 days in the west to 100 days in the northeast and southeast. Average summer monsoon rainfall ranges from 1200 mm in the west to 3000 mm in the northeast and southeast. During the wettest monsoon season at three stations the periods of consecutive rain days range from 8-10 days in the west to 30-40 days in the northeast. During the driest monsoon season at these stations the periods of consecutive rain days vary from 3-6 days in the west to 20-30 days in the northeast. Frequency of consecutive rain days of various durations at these stations in the 35-yr. period shows that episodes with duration of 1-3 days are most common. However, episodes of much longer consecutive rain days also occur, ranging from 10-19 days in the west to 18-35 days in the southeast, and 20-44 days in the northeast.