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‘Red Alert’? The Winds and the Sea Tell a Different Story…


“Pooja told me yesterday that the weathermen had issued a Red Alert for Chennai predicting heavy rains for today (November 17),” said Palayam. “How can I agree? The water and winds tell a different story.”

Yesterday, a kachan kodai wind was blowing steadily from the southwest and the shore current thendi (from the south). Thendi currents are an oddity during the northeast monsoon, Palayam said. Only vanni currents should flow from the north.

This morning when Palayam and I went to the estuary, we noticed that the winds had shifted towards the north, but the current, though weakened, remained thendi. The skies were clear with no hint of fog. The sea had had a makeover. It was calm with gentle swells. There was no evidence of the angry, frothing rollers of churned up slush, sewage sludge and plastic that was assailing the beach last week.  The stormy low-pressure of the week of November 7 brought heavy rains to the city. It lasted as long as the deadly kun vadai winds blew from the northwest, and ended only after the calming thennal  began gusting from the south.

Explaining his skepticism of the ‘red alert’ for today, Palayam said to me this morning: “I have told you earlier that as long as the shore current is thendi, it will break the rain clouds and kill the prospects of heavy rain along the coast. The fact that the wind has swung to the north, and the current has weakened suggests that some weather is building up. But when the current is still flowing from the south, how can I as a fisherman endorse the weather man’s Red Alert? This current is shifting. That is clear.” He throws a heavy piece of wood into the water. It moves very weakly, doubtfully to the north. “See! Thendi summa irukku. The thendi current is weak.”

By 1:30 pm, less than 10 hours after our conversation, clouds gathered overhead and darkened the sky. As I finished lunch, there was a short downpour that lasted less than 10 minutes, and then a steady patter of rain, like the wet nonsense rain that England gets – enough to wet the pitch and spoil the game of cricket but not heavy enough to call off the match. Palayam does not consider this downpour to be reportable as rain, leave alone heavy rains. He has told me that before. But still, I was curious to know if he had a revised forecast.

When I called him at 1:45 pm, he had already returned from a visit to the beach, the second today, to study the conditions. “karsala mariduchu anna (The shore current has shifted, brother),” he said. The weak thendi of this morning had been replaced by a steady vanni aided by a nedun vadai breeze that was gusting from the north.

With the return of the vanni, the northeast monsoon season’s normalcy had been restored. Now, one necessary but insufficient condition for a storm was in place. “Until the wind swings to kun vadai (from northwest), we are unlikely to see heavy rains. Remember that kun vadai is the visha kaathu (deadly breeze)! With it will come rains and storms,” Palayam explained over phone.

“I know they are saying heavy rains for today. But for that to happen, the wind will have to shift from the north to north-northwest. Vadai nal-la kaathu kun vadaiya ora kaatha irukkum pothu thaan karaikku puyal varum. (During the northeast monsoon, the coast will witness storms only when there is a wicked breeze from the northwest.) That looks set to happen. At this rate, though, that may not happen till late tonight or even later. Perhaps, tomorrow we may wake up to some real rough weather. But today…?”

The post ‘Red Alert’? The Winds and the Sea Tell a Different Story… appeared first on The Wire Science.

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