IMD’s weather forecast has become more accurate with time, know which things still need upgrading

New Delhi: Till a few years ago, the forecasting of the Meteorological Department was limited. Perhaps mainly to predicting rainfall during monsoon or giving maximum and minimum temperatures in four metros. Although the department was also doing many other valuable works, they did not seem to be very relevant to the general public. Its situation has changed dramatically in the last decade. Now the general public is also taking updates of the weather every moment, their interest in reading and watching weather news and its forecasts has increased. Now the Meteorological Department (IMD) is providing information every day not only about rain but all types of weather events. Not only this, the accuracy of the Meteorological Department has also increased with time. Due to increased accuracy in weather forecasting, people’s trust has increased significantly. Its demand has increased in view of the increasing cases of extreme weather events due to climate change and sometimes these turning into disasters. To meet this increasing need, the government is planning to upgrade the existing capabilities of IMD on a large scale.

Continuous improvement
Upgrading of weather forecasting infrastructure, technology and skills is a continuous process. A major impetus came in 2012 in the form of the Monsoon Mission, aimed at improving long-term monsoon forecasting, crucial to the government’s economic planning. Subsequently, several other initiatives were launched to improve the observation network, install high-performance computing systems, deploy sophisticated equipment such as Doppler radars and develop better computer simulation models. As a result, the IMD now has a much improved monitoring and observation network, much more data and increased computing power. This has enabled the IMD to provide much better weather forecasts and more people-centric information such as real-time forecasts and heatwave warnings.

What is the capacity of the Meteorological Department?
A major change in public perception about weather forecasting has come with IMD’s success in forecasting cyclones. Timely and accurate forecasting of cyclones, starting with Phailin in October 2013, led to the establishment of a reliable response and relocation mechanism, which resulted in little or no loss of human life, previously in the hundreds. The success of the cyclone early warning system has given IMD a lot of credibility. Its long-range monsoon forecasts have also been correct almost every time in the last decade. However, accurately forecasting hyper-local events like a short spell of heavy rain in a particular part of a city remains a challenge, and so is predicting extreme events that are on the rise due to climate change.

An uncertain science
Over the past decade, as IMD has enhanced its forecasting skills and capabilities, climate change has made weather patterns more erratic. In general, forecasting weather in the tropics is more challenging than in regions away from the equator, as weather events have greater variability. Also, large systems such as monsoons or cyclones that spread over large geographical areas are relatively easier to predict. A widespread heatwave is easier to predict than a local cloud-rainfall event. Similarly, regular cyclical events are relatively easier to predict than sudden, unpredictable events. There are inherent uncertainties in the science of weather forecasting. The more precise the forecast in terms of the spatial spread of the event, the greater the uncertainty. Also, the earlier the forecast is made, the less accurate it is likely to be.

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For the same reason, while forecasts for the four-month monsoon season across the country have been generally accurate over the past decade, regional and monthly predictions have been much less accurate. As another example, the IMD has a 97-99 percent chance of detecting a heat wave at least 24 hours in advance; for a heavy rainfall event the probability is less than 80 percent. Extreme weather events are even more difficult to forecast. Events that might happen only once in 50 or 100 years cannot be easily captured by models. Such events are now occurring with alarming regularity, often triggering disasters such as the deadly landslides in Kerala last month.

Accuracy required
IMD currently has the capability to forecast weather events in a 12 km x 12 km area. This grid is larger than most Indian cities – meaning that the probability of rainfall in a city can be predicted, but not exactly where in the city it will rain.

IMD is trying out experimental forecasts for 3 km x 3 km grids, but the ultimate aim is to achieve hyper-local forecasts for 1 km x 1 km areas. Such forecasts can be extremely helpful, not only for people to plan their activities but also in creating early warning systems for disasters. Previous upgrades in IMD were mainly focused on infrastructure enhancement. Some infrastructure upgrades are still required. For example, in setting up marine observation systems and high resolution earth observation satellites. Also, the eastern and northeastern regions of the country do not have optimal coverage of Doppler radars, but the major breakthrough is needed in developing India-specific weather models that are able to understand and simulate Indian conditions more accurately.

With increasing uncertainty in weather systems due to climate change, the global models currently in use have their limitations. Developing such optimized models is one of the main objectives of the planned upgrade, which will require intensive research and development and regional assessments of climate change.