In January, Chennai and other delta regions of Tamil Nadu witnessed heavy rains, which usually end in December, due to the delayed onset of North-East monsoon.
Just ten days have passed since Chennai residents experienced rainy days and chilly weather, inspiring many to dig into a plate of “molaga bajji” to enjoy the day. While the rains were moderate and enjoyable in the city, many parts of the delta districts of the state, on the other hand, experienced surplus rains and had to face difficulties. Farmers were impacted because crops on several acres of their land were damaged as the rains, which usually end in December in the state, continued till January 2021.
However, as the state is returning back to normalcy, there is speculation that Tamil Nadu will continue to receive heavy rains in February as well. Weather blogger Pradeep John said, “We will experience abnormal rains in February. After historic January rainfall in Tamil Nadu, we are heading towards a historic February rainfall.”
“Coming to February, we can’t expect 100 mm in Tamil Nadu but for sure, there is going to abnormal rains this February. The last time, February got massive rains was in the year 2002. Delta got massive rains and floods in February 2002. While Cuddalore got massive rains in February 2000 (sic),” he said, on his social media page.
His post immediately led to a discussion among users whether the state, which has already experienced surplus rainfall, will experience “abnormal rainfall.” However, other weather bloggers, as well as the Regional Meteorological Department in Chennai, have a different prediction.
Independent weather blogger K Srikanth, who handles the social media handle called ‘Chennai Rains,’ said that while chances of heavy rainfall are not very likely, Tamil Nadu may see scattered rainfall.
“We will only be having easterlies (winds blowing towards east) during this period and they cannot independently cause rains. There are only small windows for collision with westerly (winds blowing from west). So, a few models are estimating heavy rains in February as well. However, I don’t think there will be heavy rains and we may just have light showers,” he said.
Srikanth also said that the rains till January 15 cannot be called as “unseasonal” rains since the onset of monsoon was delayed. Srikanth said, “We cannot say that the rains till January 15 are unseasonal. There are chances for rains till Pongal. The North-East monsoon picked up only by November 15 so the withdrawal of the monsoon was also late.”
North-East Monsoon and the La Nina effect
While weather bloggers predict mild to moderate rainfall, the officials of Regional Meteorological Centre in Chennai have predicted dry weather in the state.
Puviarasan, the Director of Area Cyclone Warning Centre in Chennai said that the reason for the rains in January was due to the extension of North-East monsoon and hence, a mostly dry weather condition will prevail in the state during the coming months.
“Tamil Nadu received excess rainfall this year due to the extension of the North-East monsoon and La Nina effect. As a result of the heavy rains, several crops that were ready for harvest were submerged,” he said.
The La Nina effect is a weather pattern that arises due to the variations in the ocean temperature every few years at the equatorial band of Pacific Ocean. The La Nina effect causes strong winds that take warm water from the ocean near South America to Indonesia through the Pacific Ocean. Since the warm water travels over a quarter of the world, it creates a significant effect on the weather pattern across the globe.
Even in the past, La Nina has brought surplus rainfall to the state, Puviarasan said. During December, the La Nina effect was at a peak, bringing rains to the state. However, now the wind pattern has changed reducing the La Nina effect. “After some time, La Nina will become neutral and we cannot predict if La Nina effect will bring the same amount of rains next time,” he said.
The state even received surplus rains as a result of the La Nina effect, he added. Chennai received surplus rainfall by 839% and Coimbatore received surplus rain by 1163%. While Chennai expected a normal rainfall of 20.7 mm in January, the city received 194.4 mm of rainfall. The least district to record a surplus rainfall was Tiruvannamalai. While the district expected 11.1 mm of rainfall, Tiruvannamalai received 52.7 mm rainfall.
Puviarasan said, “The South Asian Forum predicted a rain deficit to the state but the reality was different. We were getting deficit rain in October but the monsoon picked up in November. Following this, the La Nina effect started bringing high-intensity surplus rainfall in the state.”
In 2020, the Cyclone Burevi and Cyclone Nivar had also brought high-intensity rains to the state. Hence, the high-intensity rainfall in the state can become a trend, the weather bloggers have said. Srikanth said, “The high-intensity rains like the ones brought by Cyclone Burevi will continue and become a trend in the coming days. As per my prediction, the warmer ocean creates more moisture resulting in high-intensity rains. So the reason for such instances can be the warmer ocean.”
Source: The News Minute