Tamil Nadu is a rain shadow area as less rain is observed in the region during the Southwest Monsoon season. However, it was one of the very few pockets that observed a surplus of 4% in June, while the entire country was experiencing scanty or deficit rain.
Being in the rain shadow area, even a minor fluctuation in rainfall amounts either pushes up the deficit figure or pulls it down. This can easily be understood from the fact that June was surplus, while July was deficit by 25%.
As of date (from 1st June) the deficit now stands at 2% and the total amount of rainfall that the region has observed during the period is 137.9 mm against the average of 141 mm.
During the active Monsoon phase, rainfall in the region is not adequate as the Western Ghats block the flow of Monsoon air, giving all the rain to Kerala. On the contrary, we see enhanced rainfall activity along coastal Tamil Nadu during the weak Monsoon phase. This is because of the westerly winds getting weak and giving rise to sea breeze along the coast during afternoon and evening hours.
Also, during the weak and break Monsoon conditions, Monsoon systems have a tendency to appear in the lower latitudes in the Bay of Bengal off Tamil Nadu and Andhra Pradesh coast.
The weather in Chennai is also governed by these factors. The city has been observing rain almost every day in August, except on the 5th and the 8th. Till the 13th of August the city has experienced 97 mm of rain against the monthly average of 140 mm. And conditions are looking conducive for some good rain in a week or so.
The highest amount of rain received in the month of August in last ten years in Chennai is 368.9 mm, recorded in 2011. The lowest has been 47.1 mm, observed in 2004.
Picture courtesy: livechennai.com
