Monsoon forecasting by IMD
Also called: Long range forecast · Topic: Climate of India and the Monsoon · NCERT: Class 11, Ch 4 "Climate"
Meaning
The India Meteorological Department (IMD), founded in 1875, predicts how much rain the monsoon will bring. It gives a long-range forecast in mid-April and an update at the end of May. Forecasts are stated as a percentage of the Long Period Average (LPA, about 87 cm). NCERT mentions a 16-indicator model, but it was used only from 1988 to 2002 and is now outdated. Since 2021 the IMD has used a Multi-Model Ensemble. This combines several dynamical models (computer models of the ocean and the air) to make one forecast. Farmers, governments and markets plan sowing, water use and food stocks on the basis of these forecasts.
Example
For 2024 the season ended at 108% of LPA, which falls in the "above normal" class (105-110%). End-of-season figures like this are checked against the April and May forecasts.
Don't confuse with
- National Monsoon Mission: the research programme (MoES, 2012, led by IITM Pune) that built the coupled models. The IMD is the agency that issues the forecasts.
Related concepts
- Monsoon and the Indian economy
- Monsoon failure
- National Monsoon Mission
- Long Period Average of monsoon rainfall
- IMD monsoon rainfall categories