Understanding the Monsoon 'Break'
The current slowdown is what meteorologists call a 'break' phase in the monsoon. This is a normal, recurring feature of the four-month season. During a break, the monsoon trough—an elongated low-pressure area that is the lifeline of the rains—shifts northwards
towards the foothills of the Himalayas. This causes heavy rainfall in the northeastern states and the Himalayan foothills, but leads to a significant reduction in rainfall over the plains and peninsular India. As of early September, large parts of North, Northwest, and Peninsular India are experiencing dry weather and clearer skies as a result of this shift.
The Primary Driver of Revival: The Bay of Bengal
The single most important factor for reviving a stalled monsoon is the formation of a low-pressure system in the Bay of Bengal. These systems act like powerful engines, drawing in moisture-laden winds from the sea and pulling the monsoon trough southwards, back to its normal position over the heart of the country. Forecasters are closely watching for signs of such systems developing, as they are crucial for restarting widespread rainfall across eastern, central, and northern India. The first half of September is considered critical, and the development of these systems will largely determine the monsoon's performance in its final month.
The Global Player: Madden-Julian Oscillation (MJO)
Another key player is the Madden-Julian Oscillation (MJO), a large, eastward-moving pulse of clouds, wind, and rain that circles the equator every 30 to 60 days. When the MJO is in its 'active' phase over the Indian Ocean, it enhances convection and can trigger more rainfall during the monsoon. Conversely, when its active phase moves over the Pacific, it can lead to a suppressed or 'break' phase over India. Meteorologists monitor the MJO's position and strength to predict intra-seasonal variations. A favourable MJO phase moving into the Indian Ocean can provide the large-scale atmospheric support needed for a monsoon revival.
What the Forecast Says
The India Meteorological Department (IMD) has noted that while overall rainfall in September might be below normal for the country, some parts are still expected to see rain. As of September 8, rain has eased over peninsular India, but active systems are bringing heavy showers to eastern and central parts of the country, like Uttar Pradesh and Bihar. While dry northwesterly winds are bringing a temporary pause to rains in areas like Delhi-NCR and Rajasthan, a revival of rainfall activity is being forecast for around September 12 in some regions. Heavy rainfall is also predicted to continue in states like Madhya Pradesh and Uttarakhand through the second week of September.
The Influence of El Niño
Overlaying these shorter-term factors is the influence of the ongoing strong El Niño in the Pacific Ocean. El Niño, which is the unusual warming of the Pacific, generally has a suppressive effect on the Indian monsoon, often leading to drier conditions and higher temperatures. The IMD has noted that these conditions are expected to strengthen in the coming months. This larger climatic pattern makes the formation of rain-bearing systems in the Bay of Bengal even more critical to counteract the drying effect of El Niño and ensure a healthy conclusion to the monsoon season.
