Chennai Deluge

Subject – Geography

Context – Chennai deluge likely handiwork of winter weather system over North India

Concept –

Chennai deluge is because of the resetting of the seasonal anticyclone over Rajasthan and its neighbourhood bringing its southern flanks to bear on the South Peninsula.
The anticyclone with its clockwise movement of air establishes over North India to preside over the winter.
The clockwise motion forces the air to sink to the ground level, and along with it, the chill that north-westerly winds from across the international border with Pakistan fetch.
The recent spurt in western disturbance activity had forced this anticyclone to move south of its normal position – down to the latitude of Maharashtra, Telangana and North Karnataka.
Its eastern flanks bore down heavy on the Bay of Bengal, suddenly altering the wind flows therein.
The clockwise winds of the anticyclone worked up on the easterly to north-easterly flows of the North-East monsoon across the Bay.
Late December also represents the fag-end of the North-East monsoon, but the overwhelming influence of the anticyclone on easterlies suddenly added a sting in its tail.