Subdued monsoon leaves climate agencies re-evaluating forecasts

While IMD predicted above-normal rain for July, global agencies tempered their forecasts
A major factor influencing the monsoon season is the positive position of the Indian Ocean Dipole (IOD).
A major factor influencing the monsoon season is the positive position of the Indian Ocean Dipole (IOD). Photo | Express

THIRUVANANTHAPURAM: The subdued onset of the southwest monsoon has led several climate agencies to revise their rainfall expectations for Kerala in July. While the India Meteorological Department (IMD) initially predicted above-normal rainfall for the month, other global weather agencies, including United States Climate Prediction Center (CPC) and Europe’s ECMWF, have tempered their forecasts. Skymet Weather, a private agency, concurred, indicating a lack of triggers to intensify monsoon rains in early July.

Weather experts attribute these adjustments to the lingering influence of El Niño, which typically suppresses the monsoon, and the delayed onset of La Niña, which typically enhances it. “Previously, most models suggested a potential for La Niña conditions, raising expectations for above-normal June rainfall. However, the slow start has prompted agencies to reassess,” noted Rajeevan Erikkulam, a meteorologist with the Kerala State Disaster Management Authority (KSDMA). He added that while there’s consensus on above-normal July rainfall, the excess levels remain uncertain.

Despite El Niño-Southern Oscillation (ENSO) conditions stabilising to neutral, there’s uncertainty among models about future La Niña development. The IMD’s latest Monsoon Mission Climate Forecasting System (MMCFS) model indicates that La Niña conditions are likely to develop during the second half of the monsoon season.

Along with La Niña, another major factor influencing the monsoon season is the positive position of the Indian Ocean Dipole (IOD).

The latest climate model forecasts indicate that neutral IOD conditions are likely to continue during the monsoon season.

According to Rajeev, strength of the monsoon would be influenced by regional factors as well. “The presence of favourable systems such as low pressure and monsoon depression and offshore turf could influence the monsoon. The absence of favourable low pressure was a major reason for weak monsoon in June,” he said.

July holds particular significance for Kerala’s southwest monsoon, historically delivering the most rainfall (653 mm). Although June saw the state receive 489 mm, the highest since 2020, it was 25% short of the historical average. In contrast, Tamil Nadu, typically less favoured during the southwest monsoon, received 46% above-average rainfall.

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