West Coast Gets Warmer Than East Coast: Signals Early Pre-Monsoon Over South India
Key Takeaways:
- West Coast temperatures are rising sharply into the high 30s, unlike the milder East Coast.
- Anticyclonic circulation is sustaining moist northeasterly winds and limiting eastern heating.
- Early thermal contrast signals the approaching pre-monsoon phase over South India.
- Heat low formation and wind discontinuity may trigger early pre-monsoon thunderstorms.
The West Coast is heating up faster than normal, with temperatures rising to the mid and high 30s. On the East Coast, the mercury continues to remain subdued and confined to around 30°C. A large differential is building between the two sides of Peninsular India, giving a significant lead toward the upcoming pre-monsoon season.
Day temperatures have frequently breached the 36°C mark along the West Coast, from Cochin to Ratnagiri. In between, the Coastal Karnataka region has shot up to the high 30s. Karwar and Honavar have touched 38°C and 37°C, respectively. Last week, Mumbai registered a hat trick of 35°C, quite early in the season. On the East Coast, the mercury continues to hover around 30–31°C, from Tuticorin and Puducherry to Chennai and Visakhapatnam. The main reason for this dissimilarity is the presence of an anticyclone over parts of Madhya Pradesh, North Maharashtra, and adjoining regions. This feature continues to fan northeasterly winds along the East Coast from the Bay of Bengal. This wind stream is warm, moist, and sultry in nature but restricts the abrupt rise in temperatures.
The West Coast gets swept by land winds—an extension of the northeasterlies of the East Coast—traversing across the interiors of Peninsular India until afternoon hours. Temperatures are shooting up to 38°C, and a further rise is likely. The interiors of South India are not as hot as the coastline along the Western Ghats. These are early indications of the upcoming pre-monsoon season for the southern parts of the country.
The differential between the East and West Coasts typically shrinks once the pre-monsoon season sets in over these parts. At present, there is no north–south Peninsular India trough, a trademark of the classic pre-monsoon phase. There is no offshore trough either, and the small-scale vortices along the Western Ghats are also missing. In the coming days, a heat low is likely to develop over the central parts and interiors of the peninsula. Following this, a seasonal north–south trough over deeper regions will generate the typical wind discontinuity. The margin of differential heating along the respective coastlines will reduce and likely balance out on most occasions. These features are the trademarks of the pre-monsoon season over South India. Pre-monsoon thunderstorm activity over the southern parts may commence earlier than normal this season.
