- Why in news
- On 13 August 2026, the Minister of State for Earth Sciences told Rajya Sabha that IMD's Multi-Model Ensemble system has cut the average error of its monsoon forecasts from 7.8% of the LPA (2016–20) to 2.2% (2021–25, second stage).
- What it is
- The Long Range Forecast is IMD's seasonal outlook for the Southwest Monsoon rainfall over India, issued as a percentage of the Long Period Average (LPA). The Multi-Model Ensemble combines output from several coupled dynamical climate models, so that the errors of any one model matter less. IMD uses it with the Monsoon Mission Coupled Forecasting System (MMCFS).
- First-stage error
- The first-stage forecast of 2021–2025 had an average absolute error of 3.1% of LPA.
- Two-stage strategy
- The first-stage forecast comes in April and the updated second stage in May. Monthly forecasts follow for June to September, plus a late-July update for August–September.
- Spring Predictability Barrier
- The SPB is a known challenge in seasonal prediction, especially for how ENSO evolves, and ENSO strongly influences the Indian summer monsoon.
- Climate drivers
- The MME improves the representation of ENSO and the Indian Ocean Dipole in forecasts.
- Nodal body
- IMD functions under the Ministry of Earth Sciences.
Don’t confuse with First-stage vs second-stage forecast: The first stage is issued in April and the updated second stage in May. The second-stage error was lower (2.2% against 3.1%).
Don’t confuse with ENSO vs IOD: ENSO is the Pacific Ocean warming/cooling cycle. IOD is the sea-surface temperature difference across the western and eastern Indian Ocean. Both affect the monsoon.
Science and technology: 57 Prelims questions since 2013; most test the concept behind the news, not the news itself. In Mains, 12 news-triggered questions.
Why it matters
- More accurate seasonal forecasts help farmers, water managers and policymakers plan for sowing, reservoirs and food prices.
Problems
- The Spring Predictability Barrier limits skill in forecasting ENSO before the monsoon.
- Seasonal totals can hide local and extreme rainfall variation, especially in hilly and coastal regions.
Way forward
- Keep upgrading models, computing power and observation networks under Mission Mausam.
- Pair seasonal outlooks with impact-based forecasts and multi-hazard early warnings.
Put in your answer
Mission Mausam: The government is building capacity under Mission Mausam through modernised observation systems and advanced Earth system modelling.
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UPSC’s own questions that come close to this issue, from our Prelims and Mains banks.
No practice question for this one; the card may still help an answer. Why: Forecast error fell from 7.8% to 2.2% of LPA; useful background on ENSO and IOD, but not a likely question.
Worth revising until Prelims 2028: most news questions come within two years of the event.