Driest August Since 1901: India Faces Historic Rainfall Deficit Amid Unusual Weather Patterns

Driest August Since 1901: India Faces Historic Rainfall Deficit Amid Unusual Weather Patterns

In the past months, even though many parts of the country have experienced above-average rainfall, senior meteorologists have indicated that this year’s August could potentially be one of the driest Augusts in India’s history, a phenomenon not witnessed since 1901. Experts attribute this trend to the intensified conditions of La Niña.

Furthermore, meteorological predictions suggest that this year’s monsoon could be the driest since 2015, with a recorded rainfall deficit of 13%. An official from the India Meteorological Department (IMD) mentioned that the country has witnessed a 32% deficit in rainfall until now for the month of August. Adding to this, forecasts anticipate reduced rainfall in a significant portion of the country over the next three days. Considering these factors, August 2023 could mark the driest August since 1901, with just three days left in the month.

Typically, August sees around 254.9 mm of rainfall, constituting approximately 30% of the monsoon season’s precipitation. IMD data reveals that August has witnessed rainfall deficits of 25% in 2005, 24.6% in 1965, 24.4% in 1920, 24.1% in 2009, and 24% in 1913.

Explaining the reasons behind the below-average rainfall, IMD Director-General Mrityunjay Mahapatra pointed to the influence of La Niña and the counteractive phase of the Madden-Julian Oscillation (MJO). The MJO is a marine-atmospheric phenomenon affecting weather patterns globally. Mahapatra noted that even without the conducive phase of the MJO, the presence of La Niña has led to diminished pressure systems, contributing to reduced rainfall. It’s noteworthy that India experienced above-normal rainfall in July due to the favorable phase of the MJO.

Additionally, he stated that another factor causing reduced rainfall is the scarcity of low-pressure systems in the South China Sea. These systems, which typically form above the South China Sea and progress towards the Bay of Bengal after crossing countries like Vietnam and Thailand, influence the western movement of the monsoon’s moisture-laden winds. This year, fewer such systems have developed over the South China Sea, leading to less moisture availability for the Indian subcontinent.

La Nina’s Effect and Its Impact on Climate

Under normal circumstances, when trade winds blow over the equatorial Pacific Ocean, warm water from the Pacific’s central region is carried towards Asia, replacing warm surface waters with cooler waters from deeper ocean layers. This process is known as upwelling. La Niña disrupts this process, causing the warm surface waters to pool over the western Pacific, eventually leading to the eastward shift of warm waters. This shift intensifies the Pacific jet stream, leading to increased rainfall over the western United States and heavy rainfall events in the Arabian Sea region.

In summary, the unusual weather patterns this year, driven by factors like La Nina and the MJO, have caused reduced monsoon activity and could make August 2023 one of the driest Augusts in India’s recorded history.

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