The convergence of La Nina and the Indian Ocean Dipole (IOD) during the monsoon season could potentially lead to increased rainfall across various parts of the country, affecting everything from crop yields to flood risks, according to experts.

La Nina, characterized by cooler-than-average sea surface temperatures in the Central and Eastern Pacific Ocean, and the IOD, a fluctuation of sea-surface temperatures in the Indian Ocean, are both known for their far-reaching impacts on global weather patterns. Yet, the convergence of these two phenomena during India’s critical Monsoon season presents a meteorological rarity, setting the stage for a potentially transformative weather event.

The experts said that the weather models suggest a positive IOD phase over the Equatorial Indian Ocean coinciding with the formation of La Nina in the Pacific. This synchronicity amplifies the influence of both phenomena on India’s Monsoon dynamics, hinting at increased precipitation levels and altered rainfall distribution patterns.

Of particular interest to meteorologists and climate scientists is the potential reconfiguration of the Monsoon convergence zone and associated rainfall patterns under the influence of La Nina and the IOD. Observations indicate a shift in the core Monsoon convergence area towards the westerly, with implications for rainfall distribution across India’s coastal and interior regions.

The simultaneous existence of these events, against the backdrop of the monsoon, indicates that these factors might augment peak monsoon conditions typically experienced from July to September.

 During this period, monsoon lows, or depressions, are expected to follow an extended and steady trajectory towards West-Northwestern India and the North Arabian Sea. This suggests an increase in rainfall in these areas, chiefly caused by monsoon lows during the height of the monsoon season.

 Observations of unfolding La Nina conditions and the IOD phenomenon point towards a shift in the core monsoon convergence area towards the westerly. This triggers a reaction from the Arabian Sea near the Indian coastline, inciting large-scale upward motion which supports the prevailing monsoon system, promoting increased rainfall throughout the season.

The rare co-occurrence of the IOD and La Nina phenomena, set against the monsoon framework, provides meteorologists and climate scientists with a unique opportunity to deepen their understanding of weather patterns.