New Delhi: The southwest monsoon in India is currently at a crucial juncture. Meteorologists predict that the monsoon will remain active in many parts of the country for approximately two weeks. Short-term rain systems are becoming active in northern and eastern India, while a larger tropical pattern is entering a positive phase in the southern Bay of Bengal. Together, these are creating conditions for rainfall.
What about the Indian Ocean Dipole?
The Indian Ocean Dipole (IOD) at the moment is neutral. That is, the sea surface temperature pattern in the Indian Ocean, which may either reinforce or reduce the monsoon, has not formed yet. In general, the positive IOD leads to cool water in the eastern Indian Ocean and warm water in the western one and thus to rains in India.
At the moment, the eastern tropical Indian Ocean experiences tropical westerlies, typhoons in the western Pacific, and increasing El Niño influence. Southeasterly trade winds, typical for the positive IOD, have not established yet, but thunderstorm activity persists in the eastern Indian Ocean. Thus, the atmosphere stays active enough.
What did the experts say?
The scientists noted that because of the relatively small area of the Indian Ocean, the situation here changes rather quickly. So, in case the strengthening of El Niño occurs in the coming weeks, it can lead to the formation of positive IOD. Positive IOD is usually able to neutralise some of the negative influences of El Niño.
Sea surface temperatures around Indonesia and the island of Java are gradually cooling. This cooling is linked to seasonal upwelling. Upwelling is a natural process in which cold water rises from the deep ocean. Changes in rainfall patterns in Indonesia are linked to this cooling. This can affect the weather across the broader Indo-Pacific region. These ocean changes also influence atmospheric conditions, shaping the systems associated with India’s monsoon.
What about India’s weather?
Atmospheric conditions over India are becoming favourable for rainfall. Weather experts report that short-duration rain systems are becoming more active over northern and eastern India. Furthermore, the Madden-Julian Oscillation (MJO) is entering a phase that favours cloud formation over the southern Bay of Bengal.
The MJO is a large-scale tropical weather pattern that moves areas of cloud and precipitation around the globe. When it is in its positive phase, the likelihood of moisture and rainfall increases over the Indian region.
The high-frequency mode is becoming active over North and East India, while the low-frequency BSISO or MJO is entering a positive phase over the southern Bay of Bengal. The combination of these two is creating conditions for an active monsoon phase for the next two weeks. This could lead to widespread rainfall in many parts of the country.
What about the impact of El Niño?
The state of El Niño is also important. Currently, the influence of El Niño is shaping the winds over the eastern Indian Ocean. If El Niño strengthens further, it could promote a positive IOD.
A positive IOD is generally considered beneficial for the Indian monsoon because it can offset the drying effects of El Niño. Scientists are closely monitoring these oceanic and atmospheric changes as they could play a key role in determining the rest of the monsoon season through 2026. Rainfall activity is expected to increase over North India, East India, and the Bay of Bengal over the next two weeks.
