Role of low level wind to the heavy rainfall on the east coast of the Bay of Bengal during low pressure system

Low pressure system (LPS), is a common heavy rainfall bearing phenomenon during the monsoon season (Jun-Sep) in the Indian sub-continent. In recent years, along with flood, this very heavy rainfall often causes landslides in the hilly regions of Bangladesh, which is now an emerging concern of Bangladesh disaster’s management authority. Landslide incidence happened on 28th July of 2021 at Chattogram Hill Tracts region after consecutive days of very heavy rainfall. Rainfall peak is observed before the day of the LPS. Hence, the aim of the present study was to reveal the atmospheric conditions which results in very heavy rainfall before the day of LPS genesis. In this study, WRF model of version 4.3.1 is used to simulate the atmospheric condition responsible for very heavy rainfall before the day of LPS. The present study found that the WRF model is good enough to simulate the LPS in advance for the Bay of Bengal region. On the day before LPS, moisture-laden strong low-level westerly dynamically facilitate the updraft by hitting the north-south elongated coastal mountains of Chattogram. The strong updraft supplied the abundant moisture to the mid-level of the atmosphere resulted in very heavy rainfall over Chattogram. The findings of this study will improve the understanding on the rainfall forecasting due to LPS over Bangladesh. Moreover, the vertical extension of the LPS was found higher than the usual which would be a matter of interest for the global scientific community to work on the impact of climate change on the characteristic features of the LPS.