Forecasting human heat stress: Insights from observations and WRF simulations during Bangladesh heatwaves

This study investigates the heatwave conditions in Bangladesh through the lens of thermal stress, and aims to facilitate the forecasting of thermal stress at lead times of 5–9 days using the weather prediction model, WRF. Here, the thermal stress is determined using the widely known bioclimatic index, PET (Physiologically Equivalent Temperature), and is calculated via the RayMan model. The first phase of the study involves a comprehensive analysis of observed thermal discomfort during seven major heatwave events, using data from eight divisional meteorological stations across the country. The findings reveal alarming levels of thermal strain nationwide. In the second phase, the WRF model has been used to simulate those heatwave events at 1-day lead time (D1), and its performance has been tested in predicting heat stress. The comparison of the model simulated values with the observed counterparts illustrated promising results in the employment of WRF model in predicting heat stress, particularly for the month of April. Finally, the same model configuration is used to forecast a heatwave event in April 2021 at extended lead times (D5-D9). Results indicate that the WRF model maintains commendable accuracy in simulating thermal stress even at longer forecast period.