IMD Forecasts Below Normal Monsoon Rainfall in India

Introduction to the Weather Forecast

NEW DELHI: The India Meteorological Department (IMD) has issued a concerning forecast regarding the upcoming southwest (summer) monsoon season, indicating that rainfall is expected to be ‘below normal’. This prediction raises alarms for India’s agricultural sector and the rural economy, particularly due to the growing risk of El Niño conditions, which have historically been associated with reduced rainfall in the Indian subcontinent.

Seasonal Rainfall Predictions

According to IMD chief, Mrutyunjay Mohapatra, "Quantitatively, the seasonal rainfall over the country as a whole is likely to be 92% of the Long Period Average (LPA) with a model error of +/- 5%." The LPA for seasonal rainfall, based on data from 1971 to 2020, is approximately 87 cm; thus, rainfall between 90-95% of the LPA is categorized as ‘below normal.’

High Probability of Deficient Rainfall

The IMD’s forecast indicates a 31% chance of ‘below normal’ rainfall, alongside a 35% likelihood of deficient rainfall (below 90% of the LPA). This clearly points to a heightened risk of experiencing less-than-normal rainfall across the country.

Core Monsoon Zone Affected

While a more detailed spatial distribution forecast will be available in the last week of May, an initial probability forecast reveals that the ‘monsoon core zone’—comprising much of central and western India, heavily reliant on monsoon rains for agricultural activities—will likely experience below-normal rainfall.

Implications for Agriculture and Water Supply

This predicted rainfall deficit threatens various sectors:

• Irrigation: Insufficient rain will adversely impact irrigation systems in arid and semi-arid regions.
• Drinking Water: Reduced rainfall raises concerns about drinking water availability.
• Reservoir Capacity: Impacts on reservoir levels may compromise hydro-power generation, particularly amid soaring input costs for diesel and fertilizers exacerbated by ongoing conflicts in West Asia.

Less rain impacts not only the acreage of kharif crops (summer-sown) but also rabi crops (winter-sown), leading to diminished soil moisture and lower irrigation water availability. These challenges could hinder overall food grain production, jeopardizing food security despite previous efforts to make the agricultural sector more resilient to droughts.

The Role of El Niño and Indian Ocean Dipole (IOD)

The developing El Niño conditions—characterized by warmer ocean surface temperatures in the central and eastern tropical Pacific—suggest a high likelihood of depressed rainfall during the latter half of the monsoon season (August-September). However, positive IOD conditions, which generally lead to increased rainfall, could potentially mitigate some effects of El Niño. Mohapatra stated, "We expect that this will counter the impact of El Niño during the second half of the monsoon season."

Current Climate Conditions

Currently, neutral IOD conditions prevail in the Indian Ocean. However, climate models indicate a possibility of positive IOD development towards the end of the southwest monsoon season. Additionally, the IMD noted that snow cover extent over the Northern Hemisphere during the past three months (January to March) was slightly below normal, as this too influences monsoon patterns.

Conclusion

As we approach the monsoon season, the IMD’s predictions highlight the considerable challenges facing India’s agricultural landscape. Stakeholders must remain vigilant and prepare to adapt to these potential hurdles in rainfall and water availability to ensure food security and economic stability in rural regions.