The Climate Prediction Centre of the US National Weather Service has recently released information regarding unusual weather conditions in the Arabian Sea and how they have impacted monsoon onset over the Kerala coast in India. The Center points to several key factors causing these conditions and predicts a prolonged dry spell across India throughout June.
Madden-Julian Oscillation’s Influence
One significant factor is the Madden-Julian Oscillation (MJO), an oceanic-atmospheric phenomenon having significant influence on global weather activities. Notably, it can cause major weather fluctuations in tropical regions on weekly to monthly timescales. Understood as an eastward moving ‘pulse’ of clouds, rainfall, winds, and pressure near the equator, MJO typically recurs between every 30 to 60 days. This traversing phenomenon is most prominent over the Indian and Pacific Oceans.
In the case of India’s impending monsoon, the MJO’s location and strength may play a crucial role in the development of monsoon over the next few weeks.
Role of Cyclone ‘Vayu’
Further complexity is added due to the occurrence of Cyclone ‘Vayu’. This cyclone has leveraged an MJO wave as it travelled across the West Indian Ocean and adjoining South Arabian Sea. The presence of ‘Vayu’ contributes to meteorological changes that can potentially delay or alter the predicted monsoon pattern over India.
Storm Initiation and Oceanic Circulation
Another factor at play is storm initiation, particularly over the East Indian Ocean and adjoining Bay of Bengal. These storms have led to enhanced oceanic circulation over North-East and adjoining East-Central Bay regions.
| Oceanic-Atmospheric Phenomena | Description |
|---|---|
| Madden-Julian Oscillation (MJO) | An eastward moving ‘pulse’ of clouds, rainfall, winds, and pressure near the equator, recurring every 30 to 60 days. |
| Cyclone ‘Vayu’ | A cyclone leveraging an MJO wave across the West Indian Ocean and adjoining South Arabian Sea. |
| Storm Initiation | Formation of storms over the East Indian Ocean and adjoining Bay of Bengal leading to enhanced oceanic circulation over North-East and East-Central Bay regions. |
Influence on India’s Monsoon Pattern
The aforementioned factors—Madden-Julian Oscillation, Cyclone ‘Vayu’, and storm initiation—are all playing a role in compounding the dry spell being experienced in India. As these dynamic forces interact, they significantly affect the regular Indian monsoon patterns, resulting in delayed monsoon onset, particularly over the Kerala coast. Moreover, the warm waters of the Arabian Sea exacerbate these meteorological phenomena, establishing a rare band of easterly winds over the Indian Ocean and creating conditions for the dry spell to continue throughout June.
