After wallowing for five days since onset in south Andaman Sea, the South-West monsoon has been able to break new ground in the Bay of Bengal, expanding to more areas on Thursday.
An India Met Department update said that the monsoon has covered the entire Andaman Sea, more parts of southeast Bay of Bengal and some part of south-west and east-central Bay of Bengal.
This would sustain monsoon conditions just south to the southern tip, which is its next port of call.
Some of these may touch off activity off the Kerala coast, with the local Met office predicting winds would once again turn monsoon-friendly westerly until Friday up till when forecasts were valid.
Its outlook said that strong westerly winds with speeds reaching 55 km/hr may blow along and off the Kerala coast and over Lakshadweep until Friday afternoon.
Delayed process To the east, monsoon winds continued to be strong over large parts of the Bay of Bengal but formation of a low-pressure area – which could escalate the onset process – are being discounted.
This is mainly being attributed to the delay in formation of the counterpart ‘heat low’ over west Rajasthan, which is generated after intense heating of the land there.
There is currently a widespread heat wave over an arc of region extending from north-west India into central India and adjoining north peninsular India, but not to the desired level.
Delay in heating of the land (up to even 50 deg Celsius at times) is thought to be the fallout of the unseasonal showery weather over practically the entire country during the spring-summer.
A proper ‘heat low’ represents lowering of pressure by degrees from south-west India to the lowest in the North. This alone can set up the required gradient for the monsoon winds to blow in.
Heat wave This is so because winds blow from a high-pressure area (seas around the peninsula) to that with a lower pressure (land heating up to cause air to expand lift) during the monsoon.
India Met said that the main weather features over land for the next four days would be heat wave to severe heat wave conditions over north-west, central parts and adjoining peninsula.