It's only a week into January. But Chennai has already recorded the decade’s highest rainfall for the month. Many other weather stations across the State too received a heavy downpour on Wednesday night.
With the Northeast monsoon activity intensifying over the State, the Meteorological Department has forecast widespread rainfall to continue in most parts till January 13. On Friday, one or two places in 14 districts, including Coimbatore, Tiruvarur and Madurai, may receive heavy rain. The intensity is likely to go up to very high rainfall in some places on January 10.
During the past 24 hours ending 8.30 a.m. on Thursday, Me.Mathur in Cuddalore district and Natham in Dindigul district recorded the day’s highest rainfall of 21cm each. Several other places too recorded heavy to very heavy rain.
Officials of the Meteorological Department said a cyclonic circulation over south Tamil Nadu coast and neighbourhood also influenced the rain spell. However, easterly waves were the major reason behind the incessant downpour. Many districts had already accumulated massive amounts of rainfall within the first seven days of the month.
The rainfall surplus in percentage runs into thousands in many districts. For instance, Chengalpattu district has recorded 16cm, which is 3,684% more than the monthly average of 4.2 mm for January.
The weather station in Nungambakkam has already recorded 16.1cm of rain against its monthly average of nearly 3cm. Similarly, Meenambakkam has registered nearly 23cm of rain so far this month. This is the decade’s highest rainfall during January in the city. Last year, Chennai recorded 7cm of rainfall in January, officials noted.
La Nina effect
S.Balachandran, Deputy Director General of Meteorology, Chennai, said the moisture-laden easterly winds convergence over land largely led to such heavy rainfall. “We have had instances in the past when the NE monsoon had extended till January 18. But what made this January wet spell special is the intensity of rainfall and more coverage,” he said.
La Nina conditions, a global weather phenomenon that refers to cooler sea surface temperatures over Pacific Ocean, had its effects over the NE monsoon spillover to January in the region. It had a tendency to prolong the monsoon after the official end of the season in December. “Weather models are now indicating that the rainspell may extend till the third week of January. However, its intensity may vary,” he said.
The Meteorological Department forecasts moderate rainfall to occur in some areas of Chennai till Saturday and the maximum temperature will be around 29 degree Celsius.