Delayed Monsoon Withdrawal, Low Pressure, Reversed Winds: What’s Behind the Wettest October in Decades?


Delhi has had its wettest October since 1960. Kerala is facing a flood-like situation. Himachal Pradesh and Uttarakhand have witnessed several deaths due to landslides caused by incessant rains. Heavy rain has battered West Bengal and parts of North-East as well — all of this in a month not generally known for a continuous downpour.

Experts opine a combination of factors such as delayed monsoon, development of low-pressure areas at multiple places and reversal of wind-direction have resulted in these rainfall events at several places.

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– Last week, two low-pressure systems were active simultaneously, one each over the Arabian Sea and the Bay of Bengal regions. Collectively, these triggered severe weather events over Kerala, Tamil Nadu, Andhra Pradesh, Telangana, Delhi, Madhya Pradesh, Uttarakhand, Odisha and West Bengal. For most days last week, at least two low-pressure systems remained active along the east and west coasts and over central India, bringing rains over large parts of the country.

– The southwest monsoon season normally withdraws completely by early October. During the withdrawal phase, it causes thunderstorms and localised heavy rainfall.

According to a report by The Indian Express, this year, the withdrawal began only on October 6 against a normal of September 17. So far, the monsoon has withdrawn completely from the Western, Northern, Central and Eastern India regions. But it remains active over the southern peninsula. Thus, Kerala, Tamil Nadu, Telangana, Karnataka and Andhra Pradesh have had significant rainfall during the last 10 days.

Until Monday, the monsoon had not withdrawn from Manipur, Mizoram, Tripura, parts of West Bengal and Odisha and entire southern peninsular India.

– Normally, by mid-October, the monsoon winds reverse their direction of flow from the southwest to the northeast. This year, due to the delay, there was heavy interaction of the western disturbances with the easterlies.

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