Early indications look good for this year’s monsoon. A week before the India Meteorological Department makes its prediction for the 2013 season, a private weather analytics firm has forecast normal rains in the country, which it said is expected to be 103% of the season’s average of 89cm.
Private forecaster Skymet said central India is likely to have the least fluctuation from normal through the June-September season, which should bring relief to the parched regions of Maharashtra. The predictions have an error margin of 4%, which is low given the tricky nature of monsoon forecasts.
Among the few international seasonal climate agencies that have predicted the Indian monsoon this year, at least two say is would be normal. These include the highly regarded European ECMWF and the South Korean APCC.
Skymet CEO Jatin Singh said the firm’s analysis, based on data from the US weather agency NCEP, suggests a timely start to the monsoon this year and robust rains in June and July, which should be good for kharif sowing. The rain prediction for both months is 105% of the long period average.
"Our calculations suggest there may be a slight dip in precipitation in August which can be attributed to an evolving negative Indian Ocean dipole (IOD)," Jatin Singh, CEO, Skymet.
IOD is the name given to difference in temperatures between east and west Indian Ocean, which in recent years has been shown to affect the southwest monsoon.
In terms of probabilities, Skymet gave a 44% chance of a normal monsoon (96% to 104% of average) this year and as much chance of rains being above normal (including a 15% probability of excess rains, that is, above 110%). It said the probability of rains being below 96% of the average was 12%. The rain forecast for August is 97% of average and in September 103%.
One of the main factors in favour of normal monsoons this year is the neutral state of the El Nino Southern Oscillation, which is the temperature difference between the two ends of south Pacific Ocean. A positive oscillation (known as El Nino) dampens Indian monsoon while a negative one reinforces rains.
"Only five times in the past has a neutral ENSO coincided with a drought in India. The last time that happened was in 1979. So, there is a reasonable chance that India might have a near-normal monsoon this year," Singh said.
India received just 92% rains last monsoon, which was a particularly bad year for forecasters. Skymet, which has been in the weather business for 10 years, said its beginning-of-the-season prediction last year was of 95% rains.