Eye on sky for rain and fare deal - Drizzle looms, not downpour

Rith Basu, TT,  5 October : The path of a cyclonic circulation currently positioned near the Myanmar and Bangladesh coastline will determine whether it will pour during Durga Puja or spare Calcutta the torment. Light to moderate rain is on the radar for the festive period starting Friday, although there is little chance of a washout unless the cyclonic circulation over the Bay of Bengal drastically changes course, meteorologists said.

Metro tracks the possible trajectories of the weather system that has added a dimension of uncertainty to the festive build-up.

Likely scenario

Light rain between Sashthi and Ashtami, moderate thereafter.

Trajectory: The cyclonic circulation has started to slowly move southwest and is tipped to continue in the same direction. It will reach the Odisha coast on Friday and stay put for two days before progressing towards the Odisha-Bengal coast. But there won't be heavy rain because of this, the weather office said.

Explanation: "Software projections and manual analysis both suggest an initial southwest movement of the cyclonic circulation, followed by a slight northwest movement. Light rain is expected between Sashthi and Ashtami and moderate rain thereafter when the system comes closer to the city," said G.K. Das, director of the India Meteorological Department (IMD), Calcutta.

Best-case scenario

Light rain at the most throughout Puja.

Trajectory: The cyclonic circulation continues to move southwest, reaches the Odisha coastline and stays there.

Explanation: Clouding will be sparse and rainfall light if the force with which the cyclonic circulation draws moisture-laden winds from the Bay to land lessens. "When a season is in transition, movement of weather systems can change with alterations in temperature, pressure and other such parameters. The second most likely outcome is the weather system staying on the Odisha coast till Dashami," said a weather scientist.

Worst-case scenario

Heavy rain during Puja.

Trajectory: The circulation moves west and positions itself over Calcutta.

Explanation: In the unlikely event of this happening, all the moisture drawn by the system will accumulate over the city and its surroundings. The outcome? Thick cloud formations and incessant, uniform rainfall.

"The presence of a monsoon trough might have made the difference in real terms, but the monsoon has already receded from western India and winds have started blowing from the west. This means the system won't be able to travel directly west," IMD director Das said.