Despite an unexpected bout of heavy showers which threw a wet blanket over the Onam festivities in Kerala, August will be marked as the driest-ever month in the recorded history of the State since 1901. As of August 29, Kerala received 46.2 mm of rainfall in the month, a shortfall of close to 90%.
The previous lowest in the 120-year recorded history of the southwest monsoon was 178.6 mm of rainfall registered in 1911. Further, this is the first time in the history of monsoon that August rainfall, which accounts for around 21% of the total annual southwest monsoon rainfall in Kerala, falls below the 100-mm mark. Though there is a day more left in the month, it is highly unlikely to bring a change in the August scenario, according to weathermen. The month will also be ‘the driest’ at the national level, with a rainfall deficit of over 32%.
Similarly, the lowest-ever southwest monsoon season rainfall was recorded in 1918 at a cumulative 1,104.3 mm against the typical seasonal average of 2,018 mm. It remains to be seen whether the State will be on track to record the driest-ever season.
However, amidst the disheartening trends, there are some positive meteorological indicators. First, the monsoon trough, which is still running close to the foothills of the Himalayas, is expected to shift to the south of its normal position in the first week of September.
The trough shifting southward from its normal position will enhance rain activity in Central India along with the Southern peninsula. Further, a trough, which now extends from south interior Karnataka to the Comorin area, in tandem with a cyclonic circulation over South Karnataka is expected to trigger isolated rain in Kerala for the next few days, according to India Meteorological Department (IMD) sources.
In addition, the Bureau of Meteorology, Australia, has confirmed that the latest weekly Indian Ocean Dipole (IOD) index was +1.05 °Celsius as of August 29. This is the second week it has been above the positive IOD threshold of +0.40 °C. A positive IOD is likely to enhance rainfall activity in the Indian continent, especially along the west coast, offsetting the negative impact of El Niño in the Pacific region. However, to declare the IOD event, several more weeks of the IOD index above the positive IOD threshold are required.
