IMD tweeted: "Deep depression has intensified into a cyclonic storm -- NIVAR over south-west Bay of Bengal (Cyclone alert for Tamil Nadu and Puducherry coasts - Yellow Message)."
The sudden change in weather is attributed to a deep depression over the south west Bay of Bengal, which has moved west-northwestwards and intensified into the cyclonic storm ‘Nivar’.
World Meteorological Department (WMO) has entrusted India with the responsibility of the Regional Centre of South Asia Flash Flood Guidance System for coordination, development and its implementation
The IMD has achieved significant improvement in track, landfall, intensity and adverse weather including heavy rainfall, strong wind and storm surge forecast.