The Monsoon's Puzzling Pause
As India moves into the final weeks of the monsoon season, many have experienced a significant reduction in rainfall. This 'break' period has been particularly noticeable over peninsular and southern India. The India Meteorological Department (IMD) confirmed
that rainfall activity was subdued over this region for about a week. However, this quiet spell does not mean the monsoon season is over. A lull in rainfall is a common feature of the monsoon cycle and is different from a formal withdrawal, which requires specific meteorological conditions to be met over several days.
Why Do Monsoon Breaks Happen?
These quiet spells, known as 'monsoon breaks', are a natural part of the season's rhythm. The primary cause is the movement of the monsoon trough, an elongated low-pressure zone that typically runs parallel to the Himalayas. When this trough shifts northwards towards the Himalayan foothills, rainfall abruptly decreases over the northern plains and much of the peninsula. During this phase, rain is concentrated in the Himalayan foothills and parts of northeast and southeast India. Other factors, such as the absence of strong, rain-bearing low-pressure systems and even powerful typhoons in the Pacific Ocean that can divert moisture, can also contribute to these dry periods.
A New System Brews in the Bay
The dry spell is set to be interrupted by new developments. According to the IMD, a fresh cyclonic circulation is expected to form over the central and adjoining northwest Bay of Bengal. This system is likely to develop into a low-pressure area over the same region around September 11. The formation of low-pressure systems in the Bay of Bengal is crucial for driving rainfall across the Indian mainland. When the monsoon trough's axis dips south into the Bay, it creates favourable conditions for these systems, which then move westwards, bringing widespread rain.
Which Regions Will See Rain Again?
The revival of the monsoon will not be uniform across the country. The new system is expected to primarily increase rainfall over eastern and adjoining parts of central and peninsular India. The IMD has forecast fairly widespread rain for several states. Odisha and Chhattisgarh are expected to see increased rainfall from September 10-12, with Vidarbha also getting more rain during that period. Parts of West Bengal are also expected to receive heavy rain due to the active monsoon trough and the developing low-pressure system. Meanwhile, other regions like peninsular India might remain relatively dry for a little longer, though a revival is possible after September 12.
What This Means for the Rest of the Season
This revival is critical as the four-month monsoon season enters its final phase. As of early September, the country as a whole faced a rainfall deficit. This erratic performance, with long dry spells and intense downpours, has become more common in recent years. While the new system will bring much-needed rain to some agricultural belts, the overall forecast for September was for below-normal rainfall for the country. The performance of these final few weather systems is vital for soil moisture levels ahead of the winter crop season and for replenishing water reservoirs. The monsoon's retreat is a gradual process that begins in the northwest and can take over a month to complete, meaning more rain is still possible for many.
