Why Did it Not Rain Even After IMD's Red Alert Warning in Mumbai?

The Indian Meteorological Department (IMD) issued a red alert for Mumbai but the weather department then scaled it down the alert to ‘yellow’, predicting light to moderate showers for July 26. But thus far, the city has had little to no rainfall. The IMD's alert was issued one day after heavy rains caused Mumbai and Pune to come to a complete stop.

It has been said that the weather service failed to provide accurate forecasts throughout the monsoon. Forecasts for Delhi and the National Capital Region (NCR) have also been predicted inaccurately.

To forecast weather, the IMD uses computer models and data from satellites. The INSAT satellites collect information on cloud motion, cloud top temperature, and water vapour concentration that helps with weather estimation, including rainfall, and cyclone tracking. In addition to satellites, the IMD gathers data on atmospheric temperature, wind speed, pressure, humidity, and sea surface temperatures using weather balloons, human and automatic weather stations, airplanes, ships, and ocean buoys.

India’s tropical climate makes it a challenge to predict the weather more accurately than in countries like the United States and the United Kingdom. IMD’s RK Jenamani told, "India is in a tropical zone. It is surrounded by sea and oceans and the weather is quite warm, humidity increases with high temperatures. There are several papers, tropical weather is less predictable than middle altitudes like Europe, and the US. The weather patterns in India, Bangladesh, and Pakistan are less predictable.” 

According to M Rajeevan, former secretary of the ministry of earth sciences, the IMD’s model to predict weather has improved and is at par with technology used in the US, UK and Japan. But he also admitted the weather agency sometimes makes mistakes in interpreting data and satellite images. “IMD has access to all the state-of-the-art models along with its own models. The resolution of IMD’s models has also significantly improved over the last few years… An accurate weather forecast depends on two aspects — the model and the interpretation of forecasters… models are just tools and if we are unable to look at multiple satellite images, radars and pick up hints from the models, we will still be missing the mark with forecasts. That is what seems to be happening.”