The Hindu Business Line : Rain surplus depletes to 26%

Rainfall surplus for the country as a whole has depleted to 26 per cent as on Wednesday from a 19-day-high of 45 per cent a week ago, as the monsoon withered along the west coast during the intervening period.

Lack of a trigger mechanism in the form of a `low' in the nearby seas, the incoherent phase of a monsoon-boosting Madden-Julian Oscillation (MJO) wave, and an ill-timed western Pacific typhoon are thought to have conspired to take the wind out of the monsoon's sails.

But a fresh spurt of rains forecast to unravel from Saturday is expected to make a material difference to the prevailing situation. Also being closely monitored is the dynamics of the upper air cyclonic circulation loitering in the coastal areas of Orissa and West Bengal. Its failure to intensify during the stay over seawaters has come as a damper to forecasters.

MONSOON TROUGH

On Friday, the axis of the monsoon trough passed through Ferozepur, Delhi, Mainpuri, Varanasi, Hazaribagh, Contai and southeastward to east-central Bay of Bengal. The trough will have to move to its normal position to the south for rainfall to significantly scale up in the peninsula. But this can happen only when a `low' forms in the Bay to hold the eastern end of the trough.

To the west, there are indications that a helpful circulation would pop up over the northeast Arabian Sea, which can help drive rain into the deficient Gujarat region. The European Centre for Medium-Range Weather Forecasts (ECMWF) still bets on such an outcome.

Of the 36 Met subdivisions, 27 still had excess or normal rain as on Wednesday (against 31 of the previous week). Marathawada returned the worst figures of -61 per cent (`scanty') while eight others (four in the previous week) posted up to -39 per cent in recorded rainfall (`deficient').

Of the eight `deficient' subdivisions, four were located along the west coast, two in peninsular interior and the rest in the northeast. Telengana (-15 per cent) and coastal Andhra Pradesh (-16 per cent) fell within `normal' (-19 per cent or less) but could fall to the wrong side thereof unless top-up rains fall in the region.

SURPLUS IN NORTH

In contrast, the north and northwest presented a totally different picture with almost all subdivisions building up big surpluses. Punjab (+446 per cent); West Uttar Pradesh (+326 per cent); Haryana (+322 per cent); East Rajasthan (+127 per cent); East Madhya Pradesh (+181 per cent); West Rajasthan (+102 per cent); Himachal Pradesh (+113 per cent); and West Madhya Pradesh (+87 per cent) were some among them. Most of these had ended up in the red during the last monsoon.

Meanwhile, India Meteorological Department (IMD) said in its Friday's bulletin that the cyclonic circulation coastal Orissa and West Bengal would bring fairly widespread rainfall activity with isolated heavy falls over Orissa and Chhattisgarh during the next two days.

A warning valid for the period said that isolated heavy rainfall is likely over the Northeastern States, Orissa, Chhattisgarh, north Andhra Pradesh, Uttar Pradesh, Haryana and Uttarakhand. Three days from Monday will see fairly widespread rainfall over Indo-Gangetic plains and adjoining central India.

ENHANCED RAIN

The enhanced rainfall in the plains will be spearheaded by a cyclonic circulation lying over Haryana and adjoining West Uttar Pradesh. Fairly widespread to widespread rainfall activity is likely over Punjab, Delhi and Uttarakhand also.

Rainfall activity along the west coast will scale up further. Thundershowers have been forecast at many places over Konkan and Goa. A few places in central Maharashtra and Marathawada too will receive rain during this period.

The Regional Met Centre, Chennai, said that rain or thundershowers are likely to occur at most places over coastal Karnataka, at many places over Kerala, south Interior Karnataka and north coastal Andhra Pradesh and at a few places over south coastal Andhra Pradesh, Telangana, north interior Karnataka and Lakshadweep. Isolated rain or thundershowers are likely to occur over Tamil Nadu, Puducherry and Rayalaseema.

Current meteorological analysis and Numerical Weather Prediction models suggest fairly widespread rainfall activity with isolated heavy falls is likely over west coast, Indo-Gangetic plains and adjoining central India during next four days.

More Stories on : Climate & Weather | Climate & Weather | Performance

Article E-Mail :: Comment :: Syndication :: Printer Friendly Page