IMD forecasts marginal increase in rains over TN from Friday

A fresh low-pressure area likely to form around Monday which raises hopes of reduction in rain deficit in the city

The State’s seasonal rainfall has dipped to 3% below average on Wednesday following prolonged dry weather over most parts of the State for many days now. However, the Regional Meteorological Centre (RMC), Chennai, has forecast a marginal increase in rains particularly in coastal areas from Friday.

A fresh low-pressure area that is likely to form over the south Andaman sea on Monday may revive vigorous monsoon activity over Tamil Nadu. According to a bulletin, light to moderate rains may relatively cover more coastal areas on Friday and Saturday than interior parts. Southern parts of the State may experience scattered rainfall on Sunday.

A cyclonic circulation, which is likely to emerge over south Andaman sea around Sunday and trigger a low-pressure area, has raised hopes of vigorous monsoon revival over the State. S. Balachandran, Additional Director General of Meteorology, Chennai said the system is still in its nascent stage and there may be changes in its track and intensity. The RMC is monitoring the system for its impact.

Mr. Balachandran said this monsoon, the State experienced a lesser number of weather systems and that are of low intensity. The depression that developed recently failed to give enough rain. The Madden-Julian Oscillation, an oceanic-atmospheric phenomenon influencing weather activities, was not favourable so far this monsoon.

During November alone, 11 districts fell short of their average monthly rain quota by a minimum of 26%. Ariyalur and Chennai districts have a rain deficit of 52% and 44% respectively. While 17 districts and Puducherry have managed to get normal rains this month, some districts have received surplus rains, with Kallakurichi recording an excess rainfall by 56%.

This time, there were spatial variations in rainfall even among neighbouring districts. For instance, Chengalpattu has recorded rainfall, which was surplus by 47% in November, whereas Chennai and Kancheepuram ended with rain deficit, he said.

The State’s seasonal rainfall has dropped from excess to below average till Wednesday. It has received an overall rainfall of 34.3 cm against its normal of 35.2 cm since October 1. However, a negative deviation till 19% is considered normal rainfall by the Meteorological department.