Wednesday, February 24, 2010

Weather in north-west undergoes tricky transition

Weather over north-west India, strategically crucial from the viewpoint of the health of the standing rabi crop and its prospects, is undergoing a critical transition from winter (spring) to summer.


This is the one of the most testing times to read weather and the need for accurate forecasts, especially with regard to fluctuations in temperature, cannot be gainsaid, says Dr Akhilesh Gupta, leading operational forecaster and Adviser to the Department of Science and Technology.

The 2009-10 winter has been one of the best with adequate rainfall and low temperatures which have stood the rabi wheat crop in great stead, Dr Gupta told Business Line.

Given this context, it is not outlandish to expect a bumper crop this year, but with a caveat. And this has reference to only the uptrend in temperature during the most vulnerable period, as emerges now, when the crop is reaching maturity.

The situation is made trickier by the fact that the harvest festival of ‘Holi' falls on March 1 this year, much earlier than usual. Normally, ‘Holi' falls in late March to coincide with the time around which harvesting operations begin.

But this time round, farmers would need to wait almost a month post-Holi for harvesting to begin. By then, the temperature regime would have made a decisive turn to inch up marking the turn from spring to summer, Dr Gupta said.

The maximum temperature is expected to start looking up as early as from this Friday February 26. A rise in maximum temperature is often mistaken to mean the advent of summer.


The transition to summer is complete only when the minimum temperatures too starts rising, which would be around March 1 this season, the day of Holi, Dr Gupta said. This would leave the crop to the mercy of the elements for at least a month.

The maximum temperature level over the plains of northwest India is currently in the range of 27-28 deg Celsius. The upper threshold limit is 30-35 deg Celsius beyond which the mercury would have a debilitating impact on the crop.

Only western disturbances, one of which is currently holding sway, can help moderate the climes in the north and northwest. But forecasts indicate no big system arriving into the northwest until March 1 to bring along cloudiness and rains. Some weak systems are expected to check in during this phase but their influence would be limited to within the hilly regions of the northwest – that is western Himalayas.


While a western disturbance is currently in the final stages of its activity over the western Himalayas, a fresh one is approaching and will start impacting the region from Wednesday, India Meteorological Department (IMD) said.


Minimum temperatures are above normal by 2-5 deg Celsius over parts of Madhya Pradesh, Rajasthan, Gujarat, Haryana, Punjab, north Karnataka and Andhra Pradesh.

Maximum temperatures too are above normal over south Maharashtra, Andhra Pradesh, Orissa, Madhya Pradesh, Chhattisgarh, Gujarat, Rajasthan, Haryana, Himachal Pradesh, Jammu and Kashmir and the north eastern States.

Isolated rain or snow has been forecast over Jammu and Kashmir during next two days and may increase thereafter. Isolated to scattered rain or snow is also likely over Himachal Pradesh from Thursday and over Uttarakhand from Friday.

Isolated light rain or thundershowers is likely over Haryana and west Uttar Pradesh during the next 24 hours. Isolated to scattered rain or thundershowers would occur over the north eastern States also.
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