Monsoon withdrawal gathers speed over North-West

The South-West monsoon has withdrawn from more parts of North-West India on Thursday even as a regime of isolated to scattered to scattered rainfall entrenches over the South Peninsula from October 15 to 17. 

East and North-East India would also slip under similar weather during these three days while isolated heavy falls are indicated over Kerala and Coastal Karnataka, India Met Department (IMD) has said. 

Thundershower regime 

This is part of the transition from South-West to North-East monsoon and is slated to continue with varying amounts of thundershowers mainly over the larger Peninsular India. 

Scattered to fairly widespread rainfall with isolated heavy falls is forecast over Assam, Meghalaya, and the North-Eastern States until Friday and the South Peninsula during the next two to three days. 

Thunderstorms accompanied with lightning is also likely over East, North-East and Peninsular India during the next two days as causative circulations and troughs continue to evolve. 

The 24 hours ending on Thursday morning saw varying amounts of rain being reported (in cm) from Digha-10; Kolkata (Alipur) and Lengpui-6 each; Jorhat- 5; Dibrugarh, Kolkata (Dum Dum) and Haldia-4 each; Passighat, Itanagar, Golaghat, Kailashahar, Alibag, Sholapur, Belagavi and Alapuzha-3 each.

Chaotic monsoon transitional weather emerged as thunderstorms broke out Madhya Maharashtra, Telangana, North Interior Karnataka, Kerala, Coastal Andhra Pradesh, Odisha, plains of Bengal, Assam and Meghalaya. 

Cyclonic whirls 

On Thursday, the IMD attributed the violent weather to cyclonic circulations over Haryana, North Bay of Bengal and adjoining Bengal and Odisha coasts, and over Coastal Andhra Pradesh. 

To the West, a prevailing circulation over East-Central Arabian Sea off the Karnataka coast has shifted to the North to lie over the East-Central Arabian Sea off the South Maharashtra-Karnataka coasts. 

To the South, a circulation lies over the Comorin, which has thrown out a trough across Tamil Nadu and Rayalaseema to in turn link with the circulation over Coastal Andhra Pradesh. 

These circulations mop up moisture from the nearby seas and feed into the trough. Warm, rising air and lower pressure around these systems cause the moisture to cool in the higher levels of the atmosphere. 

This action of warm air rising accompanied by the sinking motion of cold air (convection) plays a key role in the formation of thunderstorms that breed around the circulations and along the lines of trough. 

Withdrawal prospects 

Meanwhile, a western disturbance, a river of lower pressure streaming in the higher levels, has been located to some distance away from the Indo-Pakistan border as it makes its way in to influence local weather.

The IMD said that the monsoon has withdrawn from most parts of Punjab, entire Haryana including Chandigarh and Delhi, some parts of Uttarakhand, Uttar Pradesh, West Madhya Pradesh, East Rajasthan and most parts of West Rajasthan. 

The withdrawal line passed through Gurdaspur, Chandigarh, Haridwar, Bahraich, Sultanpur, Orai, Sawai Madhopur, and Jalore on Thursday. 

Conditions are becoming favourable for further withdrawal from remaining parts of North-West India, some parts of East India and some more parts of Central India during next two days. 

Along with the withdrawal, maximum (day) temperatures are expected to climb down by 2 to 3 deg Celsius over North-West and Central India as the autumnal weather settles down over the region. 

Source; BL