On the Predictability of the Physical and Dynamical Characteristics of the Troposphere Associated with Early Nor’westers using WRF Model

Abstract

Attempts are made to simulate the physical and dynamical characteristics of the troposphere associated with a Nor’westers (thunderstorms and hail) occurred at different places on 24 February 2016 in Bangladesh. The WRF model has simulated low pressure over West Bengal and western part of Bangladesh and the low is found to intensify during the formation and occurrence of the nor’wester. Mean sea level pressure is found to decrease by 2.27 hPa from about 0600 UTC to 0900 UTC UTC at Satkhira on 24 February 2016. Low-level circulation and strong south-southwesterly flow of winds have been simulated well by the model. The model has simulated maximum reflectivity of clouds with 50 dBZ and ice water mixing ratio is found to range between 25 and 190 mg/kg and these are simulated by WRF model with sufficient lead time of about 24 hours. Significantly ice water mixing ratio of 110-170 mg kg-1 over a greater depth from 700 hPa to 150 hPa has been responsible for enormous hails and ice pellets over Dhaka.