During this northeast monsoon season, in all the 19 districts including Chennai, Kanchipuram, Thiruvallur, among others, excessive rain showers is recorded unlike previous years.
The northeast monsoon for this year began on 28th of October. Tamil Nadu and Pondicherry received historic high levels of rainfall. Particularly, Neyveli of Cuddalore district has received 480mm rainfall. Kanchipuram stands next with 340mm rainfall. In Tamil Nadu and Pondicherry, in the past eight years (2004 to 2011), there have been normal or below normal levels of rainfall. In the past two years, there was lesser rain showers than normal levels. During 2012 and 2013, there was 16 percent and 33 percent lesser rainfall.
Generally, when there is high temperature in south pacific regions, the northeast monsoon is likely to be lesser than usual levels. This is referred to as Elnilo.
Meteorological officials say we have possibilities of receiving higher rainfall when there is low depression zone. Such a similar situation has occurred during the present year as well. During 2005, there was abnormally high levels of rain showers by 79 percent. The primary reason for surge in rainfall was low depression in the Bay of Bengal.
Reason for Excessive Rainfall
Many cyclones had formed in Bay of Bengal in 2013. These however did not approach Tamil Nadu. Hence, the state received 33 percent lesser showers in the year.
Ever since the onset of northeast monsoon this year, there have been several low pressure on the Bay of Bengal. This has given rise to increased rainfall across the state. Until 25th of November, excessive rainfall was recorded in 19 districts including Chennai, Kanchipuram, Thiruvallur, Cuddalore and Dharmapuri. In the remaining 13 districts, normal levels of rainfall was received.
Precise reports on the districts that received abnormally high levels of rainfall will be known only after the monsoon season ends.
Rainfall Records in these 19 districts is as follows
- Chennai - 1,140.4
- Cuddalore - 787.2
- Dharmapuri -399.5
- Erode - 331.1
- Kanchipuram - 626.8
- Krishnagiri - 418.3
- Nagai - 847.5
- Nilgiris - 464.7
- Perambalur - 409.5
- Pudhukottai - 394.4
- Selam – 416.1
- Thirunelveli – 715.6
- Thiruvallur – 1058.8
- Thiruvannamalai – 439.7
- Thiruvarur – 566.2
- Tuticorin – 464.5
- Vellore – 650.1
- Vilupuram – 569.8
Normal rainfall
In the 13 districts including Ariyalur, Coimbatore, Dhindugal, Karur, Madurai, Namakkal, Ramanathapuram, Sivagangai, Thanjavur, Theni, Tirupur, Trichy, and Virudhunagar, there was normal levels of rain.
In Pondichery, there was excessive rainfall. So far, 822.3mm rainfall recorded here. In Karaikkal, there was normal level of rain showers, said sources from the meteorological sources.