Lightning activity and Convective Available Potential Energy during different phases of Indian summer monsoon season over central region of India

Present work addressed the variability of lightning flash count and persistence of Convective Available Potential energy (CAPE) during onset-withdrawal and active-break phases of Indian southwest monsoon (ISM) over central India region for the period 2014–2019. We have observed that higher lightning activity is during the prior to onset phase (June) period as well withdrawal phase (September–October) of Indian southwest monsoon season. During the break phase (mid-monsoon months, July and August), the monsoon trough shifts northwards; as a result, lightning activity does not cease totally and some lightning activity is still observed over study region. It is noticed that position of monsoon trough play an important role in the lightning activity and CAPE. The analysis clearly suggests high CAPE is a necessary condition for formation of thunderstorms during ISM period (June to September). From the station based CAPE data, it is seen that lightning activity is higher at a station Nagpur (close to the monsoon trough region) compared to a station Hyderabad (far away from monsoon trough). Further, the monsoon trough region remains conditionally unstable which generates lightning producing storms over the study region during monsoon season. Observations suggest that when monsoon trough is strong, entrainment of cold and dry air in the lower level from north of monsoon trough interact with warm and moist air from south of monsoon trough and can make the atmosphere conditionally unstable that helps in formation of thunderstorms over the study region during ISM.