‘El Nino in final phase, monsoon-friendly La Nina likely to set in by September’

The monster 2015-16 El Nino may be entering its last stages, and its alter ego La Nina may begin to establish by September, according to the Australian Bureau of Meteorology.

The agency sees a 50 per cent chance of La Nina emerging in the East Equatorial Pacific, prompting it to go into ‘La Nina watch’ mode.

Six of eight international climate models suggest that the tropical Pacific Ocean will return to ‘neutral’ levels during May. Of them, seven indicate that La Nina thresholds may emerge by September. This is despite individual model outlooks showing a large spread between neutral and La Nina scenarios, the Australian agency said. The emerging snippets of information with regard to changing dynamics in the Equatorial Pacific are good news for the Indian monsoon.

La Nina has been associated with a successful Indian monsoon though with exceptions; they do not strictly have a direct cause-effect relationship.

Overall build-up in India towards May/June as evidenced in the sustained heating of the land also suggests that the ground is being prepared for a good monsoon this year.

Because, despite all its devastating impact on lives and livelihoods, the searing heat and the heat waves during April, May and June play a big role in the guaranteed performance of the monsoon.

The extent to which the plains heat up determines how far the atmospheric pressure can climb down over North India, setting up an ideal gradient from the South-West (around Kerala). The moisture-laden monsoon winds ride this pressure gradient to blow in with full force into the land and drain down its moisture in the form of heavy rain.

An outlook by India Met Department on Tuesday suggested that the ‘top heat’ driven by heat waves to severe heat waves may begin to shift to North-West India from this weekend itself. This does not mean any respite for East India, which may witness mercury peaking to new highs in the days to come.

During the 24 hours ending on Tuesday morning, Titlagarh in Odisha, the hottest place for days together, saw the maximum temperature climb down to 46 deg Celsius from 48.5 deg Celsius the previous day.

The India Met forecast said that dust storms may continue to hold down mercury over Punjab, Haryana, Chandigarh, Delhi, Uttar Pradesh and Rajasthan on Tuesday.

But heat wave conditions are forecast to develop from Wednesday over Haryana, Chandigarh, Delhi and Uttar Pradesh along with Bihar, Jharkhand, Gangetic West Bengal, Odisha, Telangana and Rayalaseema.

According to the US National Centre for Environmental Prediction, heating may extend to Rajasthan during the week ending May 4 with the extreme developing to the North-West of the State.

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