The month of October is the second rainiest month for Chennai. November being the rainiest with an average of 373.6mm is closely trailed by October with a monthly normal of 300mm rainfall. Rains have remained mild in the first week of October, but are likely to pick up in intensity and spread during this week. The transition period from the withdrawal of the Southwest Monsoon and the arrival of the Northeast Monsoon becomes quite conducive for, off and on, a fiery burst of showers over the city and suburbs.
Meteorological conditions are taking shape for increasing the rainfall activity during this week. There is a cyclonic circulation marked over the Southwest Bay of Bengal, off Sri Lanka and South Tamil Nadu coast. There is another system on the other side of the Arabian Sea, around the Lakshadweep region. These two features are joined by an east-west trough, passing through Tamil Nadu and Kerala. There is the likelihood of the Bay weather system augmenting the other one during the next 3-4 days.
The rains are likely to increase along the Tamil Nadu coast during this week. While Chennai and its suburbs may find light to moderate showers till mid-week, the southern parts are likely to get heavy rains in some pockets. After the augmentation of the weather system in the Arabian Sea, a strong stream of southerly winds will sweep across the entire coastline and interiors, as well, of Tamil Nadu. This will be the time for accentuation of weather activity all along the coast in general and Chennai, in particular. The scale and strength of rains will pick up between the 12th and 14th October. The first spell of typical post-monsoon heavy rains for Chennai is quite likely during this period. As the model reliability gets lowered after the lead time of 4-5 days, this forecast will need an update, sometime around mid-week.
Image Courtesy: The Indian Express