Agro Climate Research Centre, Tamil Nadu Agricultural University, Coimbatore based on the Southern Oscillation Index of summer season and Sea Surface Temperature values of east Pacific Ocean using Australian Rainman International V.4.3.software has come out with rain forecast for South West Monsoon for Tamil Nadu
Tamilnaud being a rain shadow region gets 32% of rain from the South West Monsoon (SWM). Famers of Dharmapuri, Krishnagiri, Salem, Nilgris Kanyakumari districts and western parts of Vellore and Tirunelveli are most benefitted from this seasonal rainfall.
The historical rainfall data collected from Tamil Nadu Agricultural University Stations were used to represent the basis for district rainfall data set. In the absence of data from research station in a particular district, data from Rainman software were used alternatively. Rainfall expected during Southwest monsoon season, 2017 with 60 per cent probability is given below.
Sixty five per cent of the geographical area of the State will be receiving the normal rainfall during this South West Monsoon season 2017.
Normal Rainfall is expected in Salem, Namakkal, Dharmapuri, Krishnagiri and The Nilgiris districts and also for Chennai, Coimbatore, Cuddalore, Dindigul, Dindigul, Erode, Kancheepuram, Kanyakumari, Madurai, Perambalur,
Pudukottai, Sivagangai, Theni, Tiruvallur, Tiruvannamalai, Villupurum and Vellore districts normal rainfall is expected.
There will be only deficit rainfall in Nagapattinam, Ramanathapuram, Tirunelveli, Tutucorin, Tiruppur, Karur, Virudhunagar, Trichy, Thanjavur, Ariyalur and Tiruvarur districts.
For the Normal rainfall forecast districts, existing agro technologies along with weather based agro advisories and normal cropping pattern may be followed.
For the Deficit rainfall forecast districts, with the available irrigation facilities, short duration less water intensive crops may be raised. This forecast can be used for making strategic agricultural farm decisions.
Southwest monsoon forecast for Tamil Nadu-2017 (District Wise):
S. No | Districts | Long Period Average Rainfall (mm) | Expected RF (mm) | Per cent Deviation | Category |
1 | The Nilgiris | 759.9 | 776 | 2 | Normal |
2 | Kanyakumari | 477.4 | 514 | 7 | Normal |
3 | Vellore | 466.1 | 470 | 1 | Normal |
4 | Chennai | 439.1 | 394 | -11 | Normal |
5 | Kancheepuram | 490.8 | 443 | -11 | Normal |
6 | Salem | 440.6 | 377 | -17 | Normal |
7 | Tiruvallur | 451.6 | 406 | -11 | Normal |
8 | Tiruvannamalai | 468.1 | 412 | -14 | Normal |
9 | Krishnagiri | 399 | 370 | -8 | Normal |
10 | Dharmapuri | 393.4 | 353 | -11 | Normal |
11 | Pudukottai | 350.6 | 325 | -8 | Normal |
12 | Cuddalore | 383.1 | 357 | -7 | Normal |
13 | Ariyalur | 392 | 310 | -26 | Deficit |
14 | Villupurum | 408.3 | 359 | -14 | Normal |
15 | Namakkal | 339.3 | 299 | -13 | Normal |
16 | Perambalur | 290.7 | 271 | -7 | Normal |
17 | Sivagangai | 301 | 325 | 7 | Normal |
18 | Trichy | 293.9 | 235 | -25 | Deficit |
19 | Maduari | 335.9 | 291 | -15 | Normal |
20 | Thanjavur | 318.4 | 252 | -26 | Deficit |
21 | Dindugal | 295.4 | 262 | -13 | Normal |
22 | Nagapattinam | 286.1 | 230 | -24 | Deficit |
23 | Thiruvarur | 296.4 | 248 | -20 | Deficit |
24 | Virudhunagar | 196.8 | 149 | -32 | Deficit |
25 | Erode | 229.8 | 202 | -14 | Normal |
26 | Karur | 213.6 | 162 | -32 | Deficit |