Cyclones form in
certain favourable atmospheric and Oceanic conditions. There are marked
seasonal variations in their places of origin, tracks and attainment of
intensities. These behaviours help in predicting their movements.
Cyclones affect both
the Bay of Bengal and the Arabian Sea. They are rare in Bay of Bengal
from January to March. Isolated ones forming in the South Bay of Bengal
move west north westwards and hit Tamil Nadu and Sri Lanka coasts. In
April and May, these form in the South and adjoining Central Bay and
move initially northwest, north and then recurve to the northeast
striking the Arakan coasts in April and Andhra-Orissa-West Bengal-Bangla
Desh coasts in May. Most of the monsoon (June - September) storms
develop in the central and in the North Bay and move
west-north-westwards affecting Andhra-Orissa-West Bengal coasts. Post
monsoon (October-December) storms form mostly in the south and the
central Bay, recurve between 150 and 18O N
affecting Tamil Nadu-Andhra Orissa-West Bengal-Bangla Desh coasts.
Cyclones do not form in
Arabian sea during the months of January, February and March and are
rare in April, July, August and September. They generally form in
southeast Arabian Sea and adjoining central Arabian Sea in the months of
May, October, November and December and in east central Arabian Sea in
the month of June. Some of the cyclones that originate in the Bay of
Bengal travel across the peninsula, weaken and emerge into Arabian Sea
as low pressure areas. These may again intensify into cyclonic storms.
Most of the storms in Arabian Sea move in west-north-westerly direction
towards Arabian Coast in the month of May and in a northerly direction
towards Gujarat Coast in the month of June. In other months, they
generally move northwest north and then recurve northeast affecting
Gujarat-Maharashtra coasts; a few, however, also move west north
westwards towards Arabian coast.
Pre and Post-monsoon
storms are more violent than the storms of the monsoon season. Life span
of a severe cyclonic storm in the Indian seas averages about 4 days from
the time it forms until the time it enters the land.