Even as the India Meteorological Department announced the arrival of the monsoon over Delhi last Saturday, and warned the country to brace itself for heavy rains for most of the week ahead, weather agencies caution that rainfall this June — less than what is usual—.has no bearing on the overall performance of the monsoon.
Last year, the searing, record-setting El Nino evaporated monsoon rains and yet June posted a 16% surplus over what it historically receives during the month. What is more, the monsoon last year — inspite of setting in over Kerala a few days late—moved so rapidly that it had covered the country by June 29.
In 2014, June rains were 54% less than the historical average of 18 cm and overall monsoon rains between June and September were 12% less than the average, giving India it’s second of three droughts in 5 years.
For Jatin Singh, CEO of Skymet, a private weather forecasting agency, the stellar monsoon last June influenced his agency to incorrectly forecast a “normal” monsoon inspite of an intransigent El Nino, defined as an anomalous heating of the Pacific Ocean that dries the monsoon 6 in 10 times.
“If you go back, the rainfall deficit was only 5% till August and then it collapsed. June and September are extremely variable months,” he said.
A forecaster, who didn’t want to be identified, said that there were years in the past when the IMD would calculate October rains as “monsoon” to make up for a weak June.
This year, inspite of monsoon rains during June short by 11% of what is usual, meteorologists are far more optimistic because the threat of an El Nino has receded. “At least for the next fortnight, I don’t see anything anomalous that will impede the monsoon,” said Mr. Singh. This is seconded by D.S. Pai, Chief Forecaster, IMD but who also cautions that forecasts could change within a fortnight.
“There is good progress. However, the intra-seasonal variability especially during June and July is exactly what makes each monsoon unique,” he said.
There was no statistical relationship between the performance of June rainfall and overall monsoon rains and that was a key reason why the IMD never issued a rain outlook for June.
“In 2010, June was severely deficit but we updated our forecast to 102% or above normal and we were proved right. There are always larger climate factors that begin to influence monsoon in July and August,” he added. A good monsoon necessarily meant continuous showers over Central India and so far that’s been the biggest laggard.
In fact, regions here such as Eastern Madhya Pradesh, Jharkhand were short on rain partly because rain bearing systems in China (that also brought rains to Uttarakhand) were preventing the monsoon clouds from firming over the region. That and the lack of rains over north Gujarat so far has meant that weather forecasters are still cagey about what the monsoon can throw up.
And then there are the breaks. While July and August are the most bountiful months of the monsoon season, it’s also the time the monsoon takes a hiatus — called a ‘break’ in the parlance — that can last for as much as a week.
Breaks are impossible to forecast and those that last for over 10 days can be the death knell for the monsoon especially because they interfere with sowing. For now, these aren’t on the IMD’s radar.
“In June, we’d said monsoon rains in July would be 107% of LPA (the 50-year average) and we’re not changing that,” said B.P. Yadav, spokesperson, IMD, “we’re going to have widespread heavy rains for the next week at least.”
Region wise, the season rainfall is likely to be 108% of its average over North-West India, 113% of LPA over Central India, 113% of LPA over South Peninsula and 94% of LPA over North-East India all with a model error of 8 %, the India Meteorological Department had said in its updated forecast in June.
