Title : High-resolution global forecast models at IITM forecasting extreme weather during the indian summer monsoon 2025
Abstract:
The Bharat Forecast System (BharatFS), developed at the Indian Institute of Tropical Meteorology (IITM), Pune, represents a major advancement in global Numerical Weather Prediction (NWP). The system is built on the Triangular Cubic Octahedral (TCo) grid formulation and operates at an effective horizontal resolution of ~6.5 km, making India the first country to operationally implement a global forecast model at kilometre-scale resolution. BharatFS was initially tested in 2022 and subsequently integrated into an extended experimental framework. Its forecast skill was evaluated comprehensively for three consecutive Southwest Monsoon seasons (JJAS 2022–2024), with particular emphasis on monsoon intraseasonal variability, synoptic-scale disturbances, and extreme precipitation events.
The evaluation demonstrates that BharatFS exhibits improved representation of monsoon dynamics, including the genesis, intensification, and propagation characteristics of monsoon lows, depressions, and associated cyclonic disturbances. The model’s ability to reproduce mesoscale convective organization and extreme rainfall intensity distributions shows a clear advancement over existing operational systems. Skill metrics based on rainfall verification, track and intensity errors, and probability-based extreme event detection indicate consistent performance improvements across the three-year period.
Following successful benchmarking, BharatFS was transferred to the India Meteorological Department (IMD) and has been running operationally for real-time forecasting since June 2025. Its seamless global, convection-permitting configuration provides enhanced predictive capability across spatial and temporal scales, supporting improved early warning of high-impact weather. The operationalization of BharatFS marks a significant step toward next-generation global modelling for the Indian monsoon system and contributes to global efforts to advance kilometre-scale Earth system prediction.
