An anticyclone over central Bay of Bengal and humid winds from the southwest direction are feeding moisture to this system. Increased moisture and cyclonic circulation will further lead to the build-up of thunderclouds in the region.
Due to this system, fairly widespread rain/thundershowers are expected over entire Northeast India including West Bengal and Sikkim. Severe thunder activities in West Bengal and Sikkim will possibly be accompanied by squally winds of 70 – 90 kmph. When the system moves away, the intensity of rain will gradually decrease.
During the pre-monsoon period, severe thunderstorm activities are common in East India, particularly Odisha, West Bengal and parts of Jharkhand including the Chotanagpur region. In the month of April and May, Northeast India is the highest contributor of rainfall amounts.
Image Credit (dandc.eu)