Date:06/05/2006 URL: http://www.thehindubusinessline.com/2006/05/06/stories/2006050602531900.htm

Back Pre-monsoon heating on in western parts

Vinson Kurian

Thiruvananthapuram , May 5

Moderate heat wave conditions are seen building in parts of west India (Rajasthan and Gujarat) and northwest and central India over the next four days in what is a known pattern in the run-up to monsoon.

An update from the National Centre for Medium Range Weather Forecasting (NCMRWF) on Friday said day temperatures hovered above 42 deg C over Rajasthan and between 40 deg C and 42 deg over Punjab, Haryana, Uttar Pradesh, Madhya Pradesh, Interior Maharashtra and the northern parts of Andhra Pradesh.

Heat wave

Predictions indicate further rise in day temperatures in some of these areas during the next three-four days. They could cross the 45 deg C-mark in extreme west Rajasthan. The rest of Rajasthan, parts of West Madhya Pradesh and South Uttar Pradesh may also see mercury touching 44 deg C during this period.

The prevailing weather could be a prelude to the establishment of the `heat low' over Rajasthan, said Dr Akhilesh Gupta of the NCMRWF. With a large footprint extending from as west as Africa, the heat low over Rajasthan plays a major role in driving the monsoon current into the mainland.

The heating must now propagate gradually to east India, which is currently experiencing some convective wet weather. "The rains here must decrease as we go forward for the heating to extend to the east, starting with a clearly featured, second heat low over Madhya Pradesh," Dr Gupta said.

This second heat low helps establish the far more important, east-to-west seasonal trough extending from central India to the east. Expected to form by late May/early June, this seasonal trough has a significant role drawing in the moisture-laden easterlies from the Bay of Bengal to bring seasonal rains to the core monsoon area of the mainland.

The seasonal trough should therefore be able to take precedence and to predominate over the North-South heat trough set up by the Rajasthan heat low, failing which the dry upper-level winds emanating from the latter could set off an intense heat wave, the like of which was witnessed during the last year.

This had caused extensive damage to life and property in East India, apart from delaying the onset of monsoon in the strategic growing areas in Central India.