Many parts of North-West India will continue to witness varyingly heavy to very rainfall for the next three to five days as the land-based monsoon trough, the spine of the monsoon, remains active over the region.

An intensified (well-marked) low-pressure area embedded into the trough makes the latter more potent, capable of generating above-normal rainfall along the area under its footprint.

While the trough itself provides for convergence of monsoon winds, the presence of an intensified 'low' within makes it a potent combination for driving up rainfall many times over.

Widespread rain

Given this, India Met Department (IMD) has forecast widespread rainfall with isolated heavy to very heavy and extremely heavy falls are very likely over Rajasthan during the next two days.

Added to this is the other major meteorological event in which the intensified 'low' sets up interaction with an incoming western disturbance, currently in the process of crossing the border from Pakistan.

Interaction between a western disturbance and the monsoon system is considered a blessing when the monsoon is not as benevolent - but it currently threatens to flood some of the affected areas.

The IMD sees fairly widespread to widespread rainfall with isolated heavy to very heavy falls over the hills of North-West, Punjab, Haryana, Chandigarh, Delhi and West Uttar Pradesh mainly on Saturday and Sunday.

This (Friday) morning, the well-marked 'low' was located over North-East Rajasthan and adjoining areas of North-West Madhya Pradesh and South-West Uttar Pradesh.

The larger monsoon trough passes through Jaisalmer, the centre of the 'low,' Shivpuri, Satna, Daltonganj, Bankura and thence into the South-West as it dips into the North-West Bay.

Secondary trough

A secondary trough, signalling the strength of the monsoon system as a whole, runs down from the 'low' to North Gujarat, extending rain bands to that region as well.

According to the IMD, the well-marked 'low' may move gradually West-North-West along the main monsoon trough and weaken by Sunday, promising widespread heavy rain for Rajasthan as mentioned earlier.

Enhanced rainfall activity with isolated heavy to very heavy rainfall is also being forecast for the hills of Bengal, Sikkim, Assam and Meghalaya as the western disturbance tracks to the East.

Meanwhile, the offshore trough, the receptacle into which the South-Westerly winds fan moisture from the Arabian Sea, however, lies truncated from Karnataka coast to Kerala coast.

But the fact that the eastern end of the trough over Central India dips into the Bay raises the possibility of a fresh cyclonic circulation developing in the area, hinted as such by an extended outlook by the IMD.

It might develop over West-Central and adjoining North-West Bay in a couple of days and move West-North-West and enhance rainfall over East and Central India during the week August 23 to 29.

So the rains might last virtually into the end of the month (August, normally the second rainiest) for East and Central India, also bringing along with the prospects for flooding/landslides.

comment COMMENT NOW