‘No science to predict isolated extreme rain’

Secretary, Ministry of Earth Sciences, Dr M Ravichandran on Monday said that the science to forecast such isolated heavy rain events “does not exist at the moment”. The IMD has maintained that the weather event at Amarnath was not a cloudburst but “localised extreme rainfall”.

“Just as there is no science to predict earthquake, there is none for isolated extremely heavy rainfall. We need to understand the process of such weather events,’’ said Dr Ravichandran, adding that no country has the science to make such a forecast.

The Secretary said the ministry is currently experimenting with drones, using them as Automatic Weather Stations (AWS) for gathering more information. The AWS drones will measure temperature, humidity and winds in an area up to 2km to make an accurate forecast.

Dr Ravichandran also said that definitions for the category of rainfall currently being used by the IMD also need to be redefined. “The ranges are shifting now. There is a definition for extremely heavy rainfall (above 204mm) but the figures have started exceeding that…so, we need to redefine,’’ he said.

The Secretary further said that even as the IMD’s forecast up to 5 daysis “very good’’, it fails in Delhi-NCR. “There is a reason for poor forecasts when it comes to Delhi. The NCR falls in the convergence zone of two weather regimes – the easterlies and low pressure areas. We predict rain by cloud cover. Though Delhi has been receiving cloud cover, this has not been converting into precipitation. We still cannot predict raindrop distribution, which varies from place to place and often depends on the terrain. For instance, similar conditions that Delhi is experiencing right now in a hilly region would have definitely brought rain,’’ he said.