Chances of the ocean warming phenomenon getting stronger are 30 per cent, suggests forecasting company
There is a 40 per cent chance that rainfall in 2014 would be less than average and a 25 per cent chance that there would be a drought, says a forecast released by private weather forecasting company Skymet. The agency has also predicted that there is no chance of excess rainfall this year.
India will receive 94 per cent of normal rains and all four months of the rainy season (June to September) will individually also receive less rain.
The “little child” at work again
The agency has blamed the El-Nino effect or the warm ocean water temperatures that develop every three to five years off the Pacific Coast in South America for the deficit in rainfall. "Among all the parameters, El-Nino has maximum correlation with rainfall in India. We use data made available by various international agencies to foresee pattern of rainfall in a year. But El-Nino is an important part of our method," said D R Sikka, former director, Indian Institute of Tropical Meteorology, Pune, who is with Skymet now.
According to the predictions made for the June-September rainy season, June and September will receive 90 per cent of the long period average rainfall, which is considered normal, July will get 94 per cent of the normal and August will get 98 per cent of it. In terms of geographical risk, Skymet suggests that northwest and west-central India will receive least rains. These regions include Rajasthan, Gujarat, Punjab, Haryana, Madhya Pradesh, Chhattisgarh, Vidarbha, Goa, parts of Karnataka and the new state of Telangana. Peninsular India will be at less risk in the rainy season.
‘Foreshadow, not a forecast’
Experts at Skymet prefer to call this foreshadow, rather than forecast. "There is an amount of certainty attached with forecast. But foreshadow is more uncertain. At this juncture, the actual amount of rainfall that India will receive is very uncertain to predict," said Jatin Singh, CEO, Skymet. Sikka said it is difficult to predict whether El-Nino will amplify or decrease the rainfall and that for this reason the level of uncertainty is high. The chances of El-Nino getting stronger are 30 per cent, according to the data.
The data shows that monsoon may halt, or move slower than normal, twice in the month of June. "This means there can be heavy showers at some places, but monsoon can slow down in covering the entire country," added Sikka.
|'Ten of 13 drought years in India since 1951 were in the years of El Nino'
When IMD already exists and gives monsoon predictions, what extra does your company bring to the domain of weather forecasting in India?
There is more information than ever before which can be easily accessed. More than 15 models across the world are analysing data constantly. If there can be more than one interpretation of the existing data, it should be made available to the public.
How is your interpretation different from IMD's?
IMD has its own advanced computer and they do their modelling. They take data from other models too. Theoretically, we give a lot of weightage to El Nino effect. We do not have our own computer, but we get data from many sources globally. We try to build consensus of models across the world. We analyse it all in the backdrop of El-nino.
Why do you give so much weightage to El Nino effect?
In 1980, scientist D R Sikka of Indian Institute of Tropical Meteorology, Pune, wrote an article about the relationship between rains in India and El Nino. That got me interested in the phenomenon. Ten out of 13 drought years of India since 1951 have been in the years of El Nino. Which means 74 per cent of the drought years had El Nino. For the years of below normal rainfall, the correlation is above 90 per cent. No other single parameter has such high correlation with monsoons in the country.
How accurate have your forecasts been in the past? Why do you prefer 'foreshadow' over forecast?
In 2012, our foreshadow was 94 per cent rains and the actual rainfall was 93 per cent of the long period average (LPA). In 2013, we suggested 103 per cent, while actual rains were 106 per cent of the LPA.
We call our predictions foreshadow because these are very uncertain. This data is to give an estimate of what might happen, so that actions can be taken beforehand in case there is high possibility of some disaster. The term forecast has some amount of certainty, while term prediction is absolutely certain.
What are the challenges in weather forecasting?
We have a good understanding at the national level and we have been giving forecasts close to actual rainfall. But we have to become strong at regional level forecasts and geographical distribution of rains. We are struggling in states like Tamil Nadu, Rajasthan and Uttarakhand. We understand Maharashtra, Karnataka and Andhra Pradesh very well.
Report: Monsoon 2013
Feature: Uncertainty quantification and reliability analysis of CMIP5 projections for the Indian summer monsoon
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