The city was lashed by another intense storm late Saturday night, the fourth such event to batter the Capital this month. While thunderstorms aren’t out of the ordinary during the pre-monsoon period, however, this year’s May has turned out to be the wettest on record—a result of an unusual confluence of weather systems and ample moisture. A waterlogged road in southwest Delhi. (Vipin Kumar/HT Photo) “This time, easterly and southeasterly moisture-laden winds from the Bay of Bengal and southwesterlies from the Arabian Sea converged in the lower troposphere over northwest India,” an IMD scientist said, stating this was aided and intensified by three prevailing weather systems. “Their interaction with mid-level dry northerlies and northwesterlies typically triggers intense thunderstorm activity. These processes were further enhanced due to a series of weather systems present over the region.” The systems in play included a western disturbance, which extended as an upper air cyclonic circulation over north Punjab and adjoining Jammu and Kashmir, with a trough aloft in the mid and upper troposphere. Additionally, upper air cyclonic circulations were …