The Ministry of Earth Sciences provided a parliamentary response detailing the performance of India Meteorological Department's flood forecasting and early warning system in Northeast India, specifically addressing the heavy rainfall event from July 18-20, 2026. IMD issued advance district-level rainfall forecasts and color-coded impact-based warnings for all Upper Assam districts including Jorhat, Golaghat, Sivasagar, and Charaideo with a 7-day lead time, accurately capturing the heavy to very heavy rainfall events.
The meteorological conditions driving the high rainfall event included a mean sea level monsoon trough extending toward Northeast Bay of Bengal on July 17, 2026, accompanied by a low-pressure area over Gangetic West Bengal and adjoining regions, plus an upper air cyclonic circulation over Northeast Assam extending up to 1.5 km above mean sea level. Between July 18-20, this circulation shifted toward Central Assam and adjoining Nagaland between 1.5 km and 3.1 km above mean sea level, supported by another upper air cyclonic circulation over North Jharkhand and adjoining Bihar with an atmospheric trough extending across Gangetic West Bengal and Bangladesh to Tripura.
IMD regularly assesses forecasting performance across four Assam sub-regions with specific metrics. In West Assam, Percentage of Correct forecasts ranges from 72.14% on Day 1 to 80.94% on Day 5, with Probability of Detection at 0.6345 (Day 1) decreasing to 0.1209 (Day 5), False Alarm Ratio from 0.738 to 0.9613, and Critical Success Index between 0.1936 and 0.0264. South Assam shows Percentage of Correct forecasts between 60.48% (Day 1) and 84.68% (Day 5), Probability of Detection from 0.525 to 0.0425, False Alarm Ratio 0.855 to 0.75, and Critical Success Index 0.12 to 0.0425.
Central Assam demonstrates Percentage of Correct forecasts improving from 66.36% (Day 1) to 80.18% (Day 5), Probability of Detection starting at 0.6929 and declining to 0.0757, False Alarm Ratio between 0.8114 and 0.8883, and Critical Success Index ranging 0.1671 to 0.0429. Northeast Assam shows strong performance with Probability of Detection at 0.7229 (Day 1) and 0.1857 (Day 5), False Alarm Ratio between 0.3913 and 0.5538, Critical Success Index from 0.4275 to 0.19, and Percentage of Correct forecasts stable at 58.47% (Day 1) and 51.61% (Day 5).
IMD's seasonal forecasting incorporates large-scale climate drivers including El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) using dynamical coupled climate models and statistical techniques assessing sea surface temperatures, atmospheric circulation, and other climate indicators. While El Niño typically associates with below-normal monsoon rainfall in most of India, Northeast India receives normal to above-normal rainfall during some El Niño years due to complex factors including Bay of Bengal moisture transport, monsoon circulation, and orographic effects. Current moderate El Niño conditions and neutral IOD status have been incorporated into seasonal rainfall outlooks.
Flood risk assessment combines seasonal climate outlooks with operational weather forecasts, with IMD's rainfall forecasts serving as meteorological inputs for Central Water Commission's flood forecasting operations that integrate hydrological observations, river gauge data, and hydrological models. To enhance forecasting capabilities, IMD has operationalized the high-resolution New Bharat Forecasting System (BharatFS) at 6 km resolution for block and panchayat levels, supported by enhanced computing power of 'Arunika' and 'Arka' systems. The Multi-Hazard Early Warning-Decision Support System (MHEW-DSS) under Mission Mausam enables real-time monitoring and forecasting, while the observational network in Northeast India is being upgraded with state-of-the-art systems.