Influence of Dry-line on the Formation of Severe Local Convective Storms of Bangladesh: A Case Study

Abstract

This study analyzes the atmospheric instability and trigger mechanisms of a Severe Local Convective Storm (SLCS) initiation over Bangladesh and adjoining Indian Territory of 4 April 2011. Two types of data, JRA-25 1.125 degree resolution reanalysis data and Global Spectral Model (GSM) 20 km resolution analyses data, both by Japan Meteorological Agency (JMA), have been used and comparisons between two products are illustrated for this case. JRA-25 reanalysis data analyses specific humidity gradient greater than 3 g/kg over 100 km, whereas the GSM data analyses specific humidity gradient greater than 10 g/kg over 100 km since sharper gradient of specific humidity is resolved in this analysis. GSM data significantly identify dry-line and can calculate instability precisely which suggests that the dry-line influences the initiation of convection in this case.