An intense rain period begins for Tamil Nadu as October gets into its second week. Dharmapuri and Coimbatore have recorded 70 mm and 17.6 mm of rainfall, respectively on October 06. While Madurai observed 13 mm and Vellore 4 mm of rainfall on October 07. According to Skymet Meteorology Division in India, the state will continue to witness the rain for the next 24 hours.
The present rain spell is the precursor to the Northeast Monsoon, particularly in the interior parts of the state that receives moderate to good showers during this period. Most of the rain is observed during the afternoon or early evening hours.
Soon after the end of Southwest Monsoon in the country, the Northeast Monsoon officially commences with the beginning of October, but we are yet to see its arrival this season.
Unlike the Southwest Monsoon, this monsoon does not have any specific date. Usually the monsoon arrives during the first fortnight of October but it is the first widespread rainfall that marks its commencement.
This monsoon is of great significance for Tamil Nadu as the state is considered to be a rain shadow area, due to which the normal rainfall is not very high during the Southwest Monsoon. The season that stretches from October to December is considered to be the rainy season for the state, as it receives its maximum annual rainfall during this time.
Rain pattern during the Northeast Monsoon
The rainfall will increase incredibly both in terms of frequency and intensity across the region, with its peak period in November. As per the Skymet Meteorology Division in India, the state will see longer rain spells that will last for three to four days at a stretch during the season. However, there will be dry spells or light rains in between.
The coastal districts of the state receive 60% of its annual rainfall, while interior parts observe 40% to 50%. Coastal cities like Chennai and Nagapattinam witness 850 mm and 950 mm of rainfall, respectively, during the season with over 400 mm of rainfall observed in November itself.
Meanwhile in interior districts, Madurai records 350 mm of rainfall in the season, with 160 mm of rainfall in October. Similarly, Trichy receives 380 mm of rainfall and its rainiest month November observes 150 mm of rain.
Cyclonic storms originating in Bay of Bengal also affects the rain pattern in Tamil Nadu. The cyclonic storms in October will not bring much rain in the state as they tend to make landfall in coastal Odisha and West Bengal.
In November, these storms head towards the coastal areas of Andhra Pradesh, which will bring some rain over parts of Tamil Nadu. However, the cyclonic storms in December mostly head for Tamil Nadu coast, which then give good showers over coastal as well as interior regions of the state.
