Rains may delay date with Kerala

The Indian Meteorological Department (IMD) on Wednesday said that the onset of monsoon over Kerala may be delayed by a week — from June...

The Indian Meteorological Department (IMD) on Wednesday said that the onset of monsoon over Kerala may be delayed by a week — from June 1 to around June 7. Based on a new statistical model developed with six predictors, the forecast has an error margin of plus or minus three days.

The six predictors are NW India’s minimum temperature, pre-monsoon rainfall peak over south peninsula, outgoing long wave radiation anomaly over the Indo-China region, south Indian Ocean sea surface temperature, south Indian Ocean lower tropospheric wind and outgoing long wave radiation anomaly over the south-west Pacific region.

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The IMD, however, maintained that the southwest monsoon seasonal rainfall is expected to be near normal. It said there is no correspondence between the monsoon date in Kerala and the subsequent performance of southwest monsoon from June to September in the country as a whole.

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On the El Nino phenomenon, the IMD said a majority of forecasts indicate that ENSO-neutral (weak warm event) conditions will prevail during the northern summer (June-August). In the second half of 2004, weak El Nino conditions prevailed over the equatorial Pacific Ocean, which started in the first week of July 2004.

From early December 2004, a cooling trend was seen in this region, which suggested a transition to neutral conditions. The IMD said that during April 2005, surface temperatures increased again in the eastern equatorial Pacific, associated with the arrival of an oceanic wave. But the effects of this present warming along the west coast of South America are expected to be brief, the IMD said.

Usually, the monsoon arrives by June 1 over south Kerala. By June 15, the monsoons — moving northwards along the western coast and northwestwards across central India — cover the whole of India.

In 1960, the monsoon arrived in Kerala on May 14. That’s considered to be the earliest arrival in the last 50 years. As for a long wait, that happened in 1972 — the arrival date was June 18.