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Heavy rains lashed Chennai and its surrounding areas due to Ditwah which is now a deep depression. The former IMD Director-General said that the cyclonic storm revealed a forecasting gap for coastline areas.
Ditwah, which is set to weaken into a depression, has been challenging as it was constantly transforming. On Dec 1 at noon, Chennai's met department issued an orange alert and quickly upgraded the alert to red only four hours later. Fluctuating wind shear, false convection build-ups and interaction with Sri Lanka landmass initially weakened Ditwah. But, surprisingly for many experts, it rebuilt its cloud mass due to warm ocean pockets off the Chennai coast.
The system has exposed the limitations of weather prediction in the Bay of Bengal, said meteorologists. While currently IMD runs weather models twice a day, that needs to change. 'What we need is a high-resolution rapid refresh,' said the former IMD chief. This mechanism helps capture what is going on throughout the day, the director-general added.