Monsoon withdrawal yet to start; rains lash parts of South

The new front opened by the monsoon over the South Peninsula continues to see action with the India Meteorological Department (IMD) forecasting heavy to very heavy rainfall over South Interior Karnataka, Tamil Nadu, Puducherry and Kerala and heavy rain over Rayalaseema, Konkan, Goa, Lakshadweep and Coastal and North Interior Karnataka today (Thursday).

A western disturbance and a remnant monsoon circulation would combine to trigger heavy rain over Jammu & Kashmir, Ladakh, Himachal Pradesh, Uttarakhand, Punjab, Haryana, Chandigarh, Delhi, West Uttar Pradesh, Rajasthan, and Madhya Pradesh. So monsoon withdrawal from West Rajasthan may take more time to start.

Monsoon trough alignment

The weaker overall monsoon over North-West and Central India is indicated best by the alignment of the parent trough whose western end lies near the normal position and the eastern end to north of its normal position. When these ends lie south of their normal positions, it provides for active monsoon conditions as were manifest through the last week.

The monsoon trough passes through Ganganagar, Hissar, Gwalior, Satna, Ranchi, Bankura and eastwards to Manipur across Bangladesh and South Assam. While not dipping into the Bay waters, the eastern end of the trough will generate easterly-to-south-easterly winds thanks to its very construction and alignment, causing rain, thundershowers and lightning across the region.

Main weather systems

A cyclonic circulation over the plains of West Bengal and adjoining Jharkhand and another cyclonic circulation over West-Central Bay of Bengal and adjoining South-West Bay of Bengal off South Coastal Andhra Pradesh-North Tamil Nadu are now the principal weather makers currently over land. It is the latter that has piloted the active monsoon front over the South Peninsula.

The former is expected to cause fairly widespread rainfall, with heavy falls, thunderstorms and lightning over East and Central India until tomorrow (Friday). Fairly widespread rainfall with isolated heavy falls, thunderstorms and lightning are also forecast for North-West India and adjoining hills today, as the western disturbance runs into monsoon easterlies.

Heavy rain forecast for South

Fairly widespread to widespread rainfall with isolated heavy falls, thunderstorms and lightning have been forecast for Peninsular India during the next three-four days as the circulation in the Bay crosses over into the Arabian Sea. Isolated heavy to very heavy falls are likely over South Interior Karnataka, Kerala and Tamil Nadu for the rest of today (Thursday).

An extended outlook from September 8-10 said that fairly widespread rainfall with isolated heavy falls may lash East, North-East, and South Peninsular India. Isolated to scattered rainfall is forecast over parts of North-West and adjoining Central India while dry weather may likely descend over Gujarat state and West Rajasthan, which witnessed flooding rain last week.