On September 30, the monsoon session will come to an end but with the development of a fresh low-pressure area over the north-east Bay of Bengal, there are no signs yet of the initiation of its withdrawal from north-west India, India Meteorological Department (IMD) said on Sunday.

K Sathi Devi, head of National Weather Forecasting Centre (NWFC) said that the low-pressure area will become more marked in the next 24 hours. The system is likely to move west-northwest wards leading to easterly winds at lower levels, which is likely to bring in a lot of moisture even to the north-western region. She further added that NWFC is not seeing any parameters of monsoon withdrawal being met in the next two days. Rainfall should stop completely but it rained in western Rajasthan on Saturday and there is water vapour in the region. It was also found that the anti-cyclonic wind pattern is not established yet. K Sathi Devi also stated that NWFC needs to monitor if conditions are becoming favourable for withdrawal after the low-pressure area weakens. But the observations by NWFC points out that monsoon season will end on September 30^th. There are no drastic changes to the season as such.

As per the new-onset and withdrawal dates of the season issued by IMD in April, September 17^th has been decided as the normal date for commencement of monsoon withdrawal from north-west India and October 15^th for complete withdrawal from the country. Until last year the normal date for commencement of withdrawal was September 1^st and the process was completed by October 15^th.

IMD, based on an analysis of monsoon data from 1961 to 2019, issued the new-onset date and the withdrawal dates issued by them are based on data from 1971 to 2019.

Last year, monsoon, against the normal date of September 1^st, started withdrawing from October 9^th and extended rains led to deluge in parts of Maharashtra, Kerala and Bihar in August. Monsoon withdrew completely in eight days by October 17^th.

There is an increase in rains across peninsular India because of the development of the low-pressure. According to the Sunday bulletin of IMD, Brahmavar in Karnataka recorded 39 centimetres (cm) of rainfall. Other areas covered in the observation were Vadakara (21 cm); Karkala (28 cm), Mulki (27 cm), Agumbe in Mangalore (22 cm), and Valprai (12 cm) in Tamil Nadu. The rainfall in these places was in extremely heavy to very heavy rain categories.

During the next two-three days, the low-pressure area over the north-east Bay of Bengal is very likely to move west-northwest wards and also have become more marked over northwest Bay of Bengal and neighbourhood during the next 24 hours.

On Monday, under the influence of this low-pressure area widespread and extremely heavy rain is very likely over Odisha, and on Monday and Tuesday, over Gangetic West Bengal, Jharkhand, Bihar. Very heavy rain is likely predicted over coastal Andhra Pradesh (AP), Yanam in Puducherry, Rayalaseema and Telangana on Monday.

Across peninsular India, an east-west shear zone is running in the middle and upper troposphere. According to the IMD bulletin, strengthening of lower-level winds and the convergence along the west coast is very likely during the next three days.

From the Bay of Bengal, due to convergence of strong moist winds, widespread rainfall in the range from heavy to very heavy is also likely over sub-Himalayan West Bengal and north-eastern states from Monday to Wednesday.

In September, all over the country, there has been a 12.5% deficiency in rainfall. It has been a 53.9% deficient over northwest India, a 32.4% in central India, and a 4.4% in east and northeast India. The peninsular India has reported 28.4% of excess rainfall till now.