With several parts of Tamil Nadu experiencing rainfall in the last few days, the stage is set for the onset of the northeast monsoon.
All features of the current spell of rain match with those of the northeast monsoon, says S.B. Thampi, Deputy Director General of Meteorology.
Going by the Meteorological Department’s bulletin issued at 8.30 a.m. Friday, conditions are becoming favourable for the commencement of the monsoon in 48 hours.
In all probability, it may set in in two days before the normal date (October 20, 2014).
24-year data
A perusal of the onset of monsoon since 1990 reveals that the onset occurred in the second half of October (16-31) on 18 occasions and in November two times (1992 and 2000). In the remaining four years (1996, 1997, 2005 and 2008), it arrived in the first half of October. In 12 years, the State experienced a normal rainfall, while it received excess in eight years.
The deficit rainfall was registered in four years, including in 2013. “This time, we are expecting a normal rainfall or slightly above normal,” adds Mr. Thampi. On an average, the State receives 44 cm during the season (October-December). If the deviation is in the range of plus or minus 19 per cent, it is called normal.
The northeast monsoon is critical to the State as it accounts for 48 per cent of the annual rainfall of 92 cm. It has acquired added importance this year as the storage in the Mettur dam is just 50 thousand million cubic feet (tmc ft).
A normal northeast monsoon is expected to result in the realisation of 60 tmc ft to 80 tmc ft through run-off for the Cauvery delta. If this happens, the samba crop can be raised comfortably, says a government official.
