Tropical cyclone (TC), one of the most devastating and deadly weather phenomena,is a result of organized intense convective activities over warm tropical oceans. In the recent years, mesoscale models are extensively used for simulation of genesis, intensification and movement of tropical cyclones. During 09-16 November, 2007, a severe cyclonic storm named, Sidr was active in the Bay of Bengal part of the Indian Ocean. At 16 UTC on 15 November 2007, the system crossed Bangladesh coast near at long. 89.8 °E. In the present study, two state-of-the-art mesoscale models, MM5 and WRF, have been used to simulate the structure and track of TC Sidr. Horizontal resolution of 90 km and 30 km respectively for mother and nested domain were used in both the models. Various meteorological fields' viz. central pressure, winds, vorticity, temperature anomaly etc. obtained from the simulations are verified against those observed to test their performance. The simulated tracks are also compared with those obtained from JTWC. The results indicate that MM5 model has better forecast skill in terms of intensity prediction but WRF model has better forecast skill in terms of track prediction of the cyclonic storm.

In this paper, an attempt has been made to study the physical and dynamical characteristics of three thunderstorms that occurred on 06 May 2017 over Mymensingh, Chuadanga, and Sylhet in Bangladesh by the WRF-ARW model of 5 and 10 km horizontal resolutions, and to find out the impacts of horizontal grid resolution for simulating thunderstorm events. The model was run for 48 h using global Final Analysis (FNL) data. Various meteorological parameters such as Mean Sea Level Pressure (MSLP), wind pattern at several pressure levels, relative humidity, and radar reflectivity along with the atmospheric instability index are analyzed and compared with the observed data of Bangladesh Meteorological Department (BMD). The model has captured the low pressure area, the conjugation of easterly and westerly wind, the presence of strong convection, high magnitude of vertical wind shear, marked dry-line, updraft, and downdraft reasonably well for the finest grid resolution. But the convective available potential energy (CAPE) value is found almost similar near the places of occurrence for both resolutions. The model performance is found precisely well for the finest than that of coarse horizontal grid resolution. Dhaka Univ. J. Sci. 69(1): 43-51, 2021 (January)

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An attempt has been made to assess the capability of the Weather Research and Forecasting (WRF) model in simulating the track and landfall characteristics of Tropical Cyclone (TC) Fani (25th April – 05th May 2019) over the Bay of Bengal (BoB). WRF model has conducted on a single domain of 10 km horizontal resolution using Global Data Assimilation System (GDAS) data (0.250×0.250). The model predicted outcomes show auspicious agreement with the observed datasets of the Bangladesh Meteorological Department (BMD) and India Meteorological Department (IMD). It is found that the diminished lead time of the model run plays a crucial role in delivering good consistency with the minimum forecast uncertainty. A strong correlation between the track and intensity forecast deviations has also been determined. According to the results, the model simulation which captures the minimum deviation in the intensity forecast also ensures better track prediction of the system. The feasibility of the track and landfall forecast by the model even up to 27 hr advance is reasonably well. Finally, it can be decided that the model is capable to predict the cyclonic storm Fani precisely and it can be chosen confidently for future events over the BoB. Dhaka Univ. J. Sci. 69(2): 101-108, 2021 (July)

Tropical Cyclone (TC) is the most devastating atmospheric incidents which occur frequently in pre-monsoon and the post-monsoon season in Bangladesh. The Bay of Bengal (BoB) is one of the most vulnerable places of TC induced storm surge. The triangular shape of BoB plays an important role to drive the sea water towards the coast and amplify the surges. In this study, minimum central pressure, maximum wind speed and track of TC Roanu are predicted by the WRF model. At the same time, prediction of cyclone induced storm surge for TC Roanu is done by using MRI storm surge model which is conducted by JMA. The input files for this parametric model is provided by using simulated data of WRF model and observed data of IMD. The results are compared with available recorded data of surge height for this cyclone. The differences in simulated output for two different input files are also studied. The maximum surge height from the MRI model is found 3 m using WRF simulated data and for IMD estimated data the maximum surge height is found 2.5 m. The simulated surge heights are found in decent contract with the available reported data of the storm surges.