Residents were in for a pleasant surprise on Sunday night as the city received light showers, just as weather bloggers had predicted.

Several areas on Chennai’s outskirts including Avadi, Poonamallee, Kelambakkam, Tambaram, Sholinganallur and Chemparambakkam, received showers, due to what the meteorological department called the ‘distance effect’.

The rains started by 12.30 a.m. and went on till 6 a.m. Residents said that many key roads were inundated.

“Though the cyclone was 1,200 km southeast of Chennai on Sunday, the city received rains. Areas closer to the cyclonic system such as Tanjore however, received no rains due to this effect. On Monday evening, the cyclone was much closer – 600 km east of Chennai, but though it was cloudy, it didn’t rain,” said Y. E. A. Raj, deputy director of meteorology, Regional Meteorological Centre.

According to met department data, though the city received just 4 mm of rain, it helped bring down the temperature.

“There was a lot of wind and we were expecting more rain. But the temperature dipped and this was a relief,” said Kumar, a resident of Perambur.

The minimum temperature on Monday was 25 degree Celsius and the maximum touched 36 degree Celsius, significantly lower than temperatures recorded over the past week.

“When there is a thunderstorm, a lot of cold air is pushed down, bringing down mercury levels rapidly,” Mr. Raj explained.

The met department apart, a group of bloggers has been keenly following Mahasen’s progress.

There have been at least 700 posts every day on, a site where amateur meteorologists discuss weather phenomena, tracking the cyclonic system’s movement. The bloggers had earlier predicted the formation of the cyclone and had also said it could cross the coast north off Andhra Pradesh and move near Bangladesh.

R. Pradeep John, a blogger explained that they use models from several countries to make predictions about the weather.

“Until Sunday, the US Navy model said the system would move north near Andhra Pradesh. However, on Monday all the models including the Canadian model, UK Met Office, Global Forecasting System and European model have predicted the cyclone’s landfall near Bangladesh. Each model considers 16-18 parameters including wind velocity, surface pressure and precipitation levels to predict the path of a system,” he added.

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