Climate Change

Monsoon 2023: Skewed rainfall distribution drowning north, northwestern India while peninsular south remains dry

Deficit rainfall in 15 subdivisions in the eastern and southern peninsula as of July 10

By Pulaha Roy
Published: Tuesday 11 July 2023
Delhi received excess rainfall on July 8 and 9, 2023. Photo: @AtishiAAP / Twitter

Despite torrential downpours in northern and northwestern India on July 8-9, 2023, large parts of the country are still facing a rainfall deficit. The deluge over the weekend only added more rainfall to the existing monsoon distribution, as southeastern and southern India still remains dry. 

The India Meteorological Department categorised monsoon rainfall in the country as ‘normal’ as of July 10, 2023. However, 15 subdivisions in the eastern and southern peninsula have deficit rainfall. 

Map: Pulaha Roy

The map above highlights the skewed and largely anomalous distribution of the rainfall this year. Through June 2023, the monsoon in India was -10 per cent deficient or in the ‘normal’ range, according to the IMD. As per IMD’s categorisation, -19 per cent to 19 per cent in excess is considered ‘normal’ rainfall. 

Western, northwestern and northern India received excess rainfall through June 30, 2023 while southern and eastern India faced a deficit, as seen in the map. 

Read more: Kharif crops take a severe hit by intense and unprecedented rainfall across India

The July downpour that hit the northern regions of the country on July 8 and 9 highlighted the large to large excess anomalous distribution of monsoon 2023 reported till now. A combination of factors have led to this anomaly. 

In June 2023, Cyclone Biparjoy led to the western and northwestern regions of the country experiencing excess to large excess rainfall while eastern and southern India remained dry due weak monsoonal rain. 

By July, a marine heatwave brewing in Bay of Bengal pumped enough moisture to the monsoon depression or low pressure area, which moved toward the northwestern regions of the country instead of going in the north-central direction. 

In a rare occurrence, this low pressure system interacted with a western disturbance to produce extreme rainfall that the northern states witnessed on July 8 and 9, 2023.

A western disturbance is an extratropical storm originating in the Mediterranean region and which normally brings sudden rainfall in the northwestern parts of the subcontinent, usually during the winters.

Taking stock of all the meteorological and climatic events, 2023 has been reporting a lot of aberrations, starting with the drier western regions of the country — Gujarat and Rajasthan — having reported excess rain in June.  

Read more: North India Deluge 2023: Yamuna crosses warning mark in Delhi amid heavy rain in upper catchment

This was followed by the marine heatwave in the Bay of Bengal. While the heatwaves are not an aberration in the region, usually, it also means a drier central region and more rainfall in the southern peninsula.

While the central regions have mostly reported normal rainfall in 2023, the peninsular south has remained dry.

The last anomaly in a chain of meteorological events in 2023 would be the interaction between the northwest-bound low pressure system and the existing western disturbance as such an interaction is rare during a monsoonal season, Down To Earth reported earlier.

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