The Hindu Business Line : Weekend rains to help lift ‘break’ phase

Thiruvananthapuram, June 24 The European Centre for Medium-Range Weather Forecasts (ECMWF) has stuck to its outlook on the monsoon coming back to life helped on by the twin ‘props’ emerging from the peninsular seas.

Two cyclonic circulations with prospects for intensification are seen springing up one after the other over northwest Bay of Bengal and north Arabian Sea. They would act as the fulcrum around which the rains would flourish over the weekend and into the next.

Most of the rains would fall in peninsular India that has seen hardly any significant rain after the initial burst .The heavy rain had shifted later to the east and northeast giving way to break monsoon-like conditions.

BREAK MONSOON

‘Break monsoon’ is the term used to describe the phase obtaining after an active wet spell runs through the course. The rain-driving monsoon trough shifts to the foothills of the Himalayas, confining rains to that belt and leaving the Indo-Gangetic plains more or less dry.

The plains may have dried up but the trough had not shifted entirely to the foothills on Tuesday and passed through Anupgarh, Bhiwani, Aligarh, Kanpur, Allahabad, Dhanbad and Contai and southeastward into east-central Bay of Bengal. .

Another classical break monsoon feature missing is the extension of monsoon westerlies in the lower troposphere right up to the rim of the Tibetan plateau. This too is known to happen with the shift of the monsoon trough to the foothills.

Dr Swadhin Behera, Sub-Leader of the Climate Variations Research Programme at the Tokyo-based Frontier Research Centre for Global Climate (FRCGC), opined that the current conditions could be equated to ‘break monsoon’ but would not last long. FRCGC is part of the Japan Agency for Marine-Earth Science and Technology (Jamstec).

WATCH MAINTAINED

On Tuesday, India Meteorological Department (IMD) maintained a watch for a burst of rainfall along the west coast over the next few days. But it seems to have withdrawn its outlook for a mid-tropospheric cyclone (MTC) over south Gujarat.

A survey of outgoing long-wave radiation (OLR) put out by various models also seemed to rule out formation of an MTC, which represents hyperactive monsoon conditions. A monsoon `low’ or depression looks a more likely possibility.

The ECMWF sees it moving east-northeast to the Konkan-Mumbai coast and setting up an interaction with an incoming ‘low’ (depression) from the northwest Bay of Bengal.

“We have not done any study to link a positive Indian Ocean Dipole (IOD) event with an MTC, or for that matter, monsoon depressions or ‘low’s. What we know is that the active spells of monsoon last longer during IOD years with less number of in-between breaks,” Dr Behera explained.

IOD represents the seesawing of sea-surface temperatures between the western Indian Ocean and equatorial East Indian Ocean. A positive IOD event drives up a concurrent Indian monsoon rainfall. The FRCGC is credited with the discovery of the IOD.

Meanwhile on Tuesday, an upper air cyclonic circulation hung over west Uttar Pradesh and adjoining northwest Madhya Pradesh. Another circulation was parked over Gangetic West Bengal and adjoining Jharkhand and Orissa. Under the influence of these systems, scattered to fairly widespread rainfall activity is likely over east and central India during the next two days.

More Stories on : Climate & Weather | Climate & Weather

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