Season’s end

Why in the News

The India Meteorological Department (IMD) forecast a “below normal” monsoon, but the season ended “deficient” at 87% of normal, the outcome its own models had pointed to. Large regional misses and State drought declarations now question whether the IMD is too conservative in warning of shortfalls.

How does the IMD forecast the monsoon, and what did it predict?

1. What a seasonal forecast is: Two IMD forecasts, in April and May, estimate the season’s rain as a share of the Long Period Average (LPA), the long term mean used as “normal”. It is like a weather report for four months.
2. Forecast categories: “Below normal” means 90% to 95% of average rain. Anything lower is “deficient”.
3. El Niño: In an El Niño year the Central Equatorial Pacific warms, which suppresses monsoon rain. Global models agreed that one of the strongest El Niño events was coming.
4. A cautious call: The IMD’s models pointed to “deficient” rain, yet it chose to forecast “below normal”.
5. The takeaway: By picking the milder category, the IMD gave less warning of a shortfall its own science saw coming.

How far did the season miss the forecast?

1. National total: The monsoon ended at 759 mm against a normal of 869 mm.
2. Technical victory: IMD forecasts allow an error window of 4% to 5%. The final figure sits inside it, so the IMD can claim only a technical success.
3. June shortfall: June got 65% of its normal rain against a forecast of 92%.
4. Northeast: The northeast, expected to be “normal”, had its driest season since 1901, falling 26% short.
5. South and the rest: The south peninsula ran 23% short. Central and north west India finished close to predictions, helped by ocean conditions.

Why are regional forecasts getting harder?

1. Climate change: Warming makes rain patterns less regular and harder to forecast.
2. Western disturbances: These extra-tropical rain bearing systems, which reach India from the west, are bringing more rain in the monsoon months, helping the north west.
3. Southern volatility: Southern India is more vulnerable to El Niño triggered volatility in rainfall.
4. Kharif sowing: Sowing of kharif (monsoon season) crops trailed last year’s by 16% in early July. By early September the gap had narrowed to under 2%.

Why does a cautious forecast matter for drought response?

1. Karnataka: The State has declared drought in over 100 taluks.
2. Maharashtra: The State has declared drought in 265 of 358 taluks.
3. National threshold: The national deficit of about 12% is below the Centre’s 20% threshold for “agricultural drought”, so the national figure masks local distress.
4. Dry months ahead: The IMD expects El Niño to bring below normal rain from October to December, threatening soil moisture and reservoir recharge.
5. Crop signals: The Cabinet raised the support price, the price the government guarantees farmers, by ₹25 a quintal for wheat and ₹413 for mustard. The larger mustard rise nudges crop diversification.

Challenges

1. Coarse resolution: National forecasts hide district level extremes that drive crop planning.
2. Institutional caution: A forecaster judged on staying within its band may prefer the milder call.
3. Shifting drivers: Pacific warming and extra-tropical systems interact differently each year, weakening models built on past patterns.
4. Threshold mismatch: A single national drought test can miss distress concentrated in a few States.

Way Forward

1. Sub-regional systems: The IMD should improve its sub-regional forecast systems and issue unwelcome forecasts plainly.
2. Show the models: The IMD should publish what its models project alongside its official category.
3. Regional probabilities: Forecasts should state the probability of deficient rain for each region.
4. Early contingency plans: States should use district forecasts to trigger alternative crop plans.

Conclusion

This monsoon showed that a forecast can be accurate for the country and still fail the regions that most needed a warning. The test now is whether the IMD’s outlook for the coming months warns districts early enough to act.

Key numbers

1. July rain: About 1 percentage point above the “below 94%” forecast.
2. August rain: 84% of the LPA, in line with the “below 94%” forecast.
3. September rain: 92.4%, a little above the forecast of “below 91%”.

Back2Basics: Types of drought

1. Meteorological drought: A significant rainfall deficiency over a period, usually 25% or more below normal. Eg. Marathwada (2015).
2. Agricultural drought: Too little soil moisture for crops, cutting yields. Eg. Bundelkhand (2016).
3. Hydrological drought: Falling river flows, reservoir storage and groundwater after prolonged rain deficits. Eg. Cauvery basin (2016).
4. Socioeconomic drought: Water scarcity that disrupts livelihoods and food security. Eg. Vidarbha (2012 to 2013).

Matching Previous Year Question

“[2017] With reference to ‘Indian Ocean Dipole (IOD)’ sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct? 1. IOD phenomenon is characterized by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean. 2. An IOD phenomenon can influence an El Nino’s impact on the monsoon. Select the correct answer using the code given below: (a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2 Answer: B”