The Northeast Monsoon covers five subdivisions of Peninsular India- Coastal Andhra Pradesh, Rayalaseema, South Interior Karnataka, Kerala and Tamil Nadu. Out of all these, Tamil Nadu is the main beneficiary during the Monsoon season that receives less rains during Southwest Monsoon because it lies in rain shadow area. According to facts, 35% of annual rainfall is during Southwest Monsoon and over 50% of rains is covered in a span of just three months during Northeast Monsoon.
As per experts, Northeast Monsoon has a large variability for all divisions. It is rarely evenly distributed among these five divisions. If we look back at the data of five years, then 2014 has been the only year when all the divisions received rainfall in negative. This variation in distribution of rains is in terms of both, space and time.
The example of large variability is that in 2015, Tamil Nadu was rain surplus by 52% and was rain deficit by 62% in the year of 2016.
| YEAR | TAMIL NADU | COASTAL ANDHRA PRADESH | RAYALASEEMA | SOUTH INTERIOR KARNATAKA | KERALA |
| 2017 | -10 | -48 | +19 | -5 | -8 |
| 2016 | -62 | -67 | -66 | -70 | -62 |
| 2015 | +52 | -15 | +78 | +17 | +27 |
| 2014 | -2 | -30 | -37 | -8 | +4 |
| 2013 | -33 | +39 | -25 | -37 | -10 |
| 2012 | -16 | +33 | -2 | -23 | -35 |
| 2011 | +22 | -45 | -18 | -1 | -7 |
The forecast for this season is that state of Tamil Nadu is supposed to receive normal rainfall which should be between 89%-111%. As per projections, it will be on the positive side of the average rainfall.
However, in this season, Northeast Monsoon did not make a promising start. The start has been a delayed and subdued one. We are already half way through the season, still the figures are not encouraging. As per the records, Tamil Nadu has been rain deficit by 19% as of now. It's a make and break situation for this particular pocket. The highest deficiency as of now has been recorded in both the subdivisions of Andhra Pradesh. Coastal Andhra Pradesh is rain deficit by 73% and Rayalaseema by 66%.
However, in coming 3 days, we expect wet spells over Tamil Nadu region commencing from November 19 up till November 22. Tamil Nadu will be the main beneficiary during this wet spell, both in terms of spread and intensity. Whereas, capital city Chennai is far far below the normal and is currently deficit by 60%. This tells that active spells in large number is needed over the city.
Image Credit: Skymet
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