Chennai: Ever wondered about the science behind the formation of storms? Last year, storms resulted in devastating rains but this year there are no rains due to the absence of tropical rain wave and southward migration of Monsoon trough (rain belt). If the situation persists, the state would face a season of mediocre agricultural produce and a huge water crisis next year.
Predictions on rainfall activity in the state have turned futile almost this entire northeast monsoon season. With experts in atmospheric science predicting a suppressing rainfall for the southern region this year, going by arterial global models, Tamil Nadu residents are staring at an alarming situation.
Attributing the low rainfall activity to the absence of Madden – Julian oscillation (MJO) wave formation, Weather Blogger, Bhaskaran Shivaraman explains, “The wave has a ripple effect on rains in Tamil Nadu. Absence of the wave is delaying the formation of storms.”
T. Gokul, an atmospheric science student and a weather forecaster said, “It is an eastward moving tropical rain wave that has two regions: Enhanced (rainfall favourable area) and suppressed (non favourable area). The wave helps in formation of low-pressure areas that bring rains. Unfortunately, in Indian region, MJO wave is in suppressed phase.”
But, however, the activity is just gaining amplitude and is setting up favorable conditions for rainfall in the Indian Ocean. Also, negative Indian Ocean Dipole (IOD) conditions resulted in relatively weak easterlies.
Another supporting factor - trough or a rain belt general term - has also advanced this year, unlike in the usual North East Monsoon scenario. It moves southward with the season advancing from October – December. Even though it is still November, the belt has already moved south.
“The current location of the trough is in the lower latitude (which is generally observed in December), resembling a winter pattern in the state. It is now at North Equatorial Indian Ocean near South of Sri Lanka,” said Gokul.
Amid all the science, people of Tamil Nadu are looking forward to November 27, as another storm formation is expected then. Will this forecast at least prove true, people are wondering.
