The Met department that had said monsoon will hit the Kerala coast on June 1,with a possible deviation of plus or minus four days,has expressed doubts on the onset date because of a low-pressure area over the Arabian Sea that is likely to intensify hampering its progress.
On Friday,the South-West Monsoon progressed over the southern part of Arabian Sea,Maldives and Comorin and the met department was hopeful of further movement. It,however, is not progressing to the mainland.
There is no clear-cut signal whether the low pressure area over the Arabian Sea is likely to intensify. If it does,it will suck up moisture and delay movement which means onset date over Kerala will be delayed,said Sunita Devi,director weather central,IMD,Pune.
The met department said they are yet to assess the intensity of the low-pressure area as models are giving divergent outputs. There is a need to check the sea surface temperature and wind direction,said a met official.
The lull in advancement has been observed for quite a few days and the onset date of June 1 would not be achieved. The South-West Monsoon advanced over Andamans by May 23,which usually sets the onset date over Kerala.
However,with conditions in the Arabian Sea not conducive,the monsoon current did not reach the mainland. Last year,the monsoon advanced over the Andamans on May 29 and it simultaneously advanced to Kerala the same day.
Normally,June 1 is the date of onset over Kerala,which is the entry point for monsoon into the Indian mainland. Historical data shows monsoon keeps its date with a standard deviation of just a week. There have,however,been instances when the onset has occurred around the middle of May or got postponed to mid-June. According to IMD statistics,the earliest recorded onset was in 1918,when it set in on May 11,and the most delayed onset was in 1972,when South West Monsoon arrived on June 19.
The IMD had issued forecast of a normal monsoon this year in April,with a rainfall of 99 per cent of the long period average with a plus or minus 5 per cent.