Sources in the meteorological office said the Andaman Sea, south of Kerala coast, is likely to receive rainfall in the third week of May, which is earlier than the normal schedule. Although that would not result in an advance of monsoon northwards as well, they said.
The Met department said in a statement that the southwest monsoon normally advances over the Andaman Sea around May 20 with a standard deviation of a week. However, this year owing to the influence of tropical cyclone 'Mahasen', currently located over the central Bay of Bengal, a low-level cross-equatorial monsoon flow appeared over the south Andaman Sea and the adjoining Bay of Bengal.
It said the further deepening of cross-equatorial flow over the next few days could result in increased rainfall over the area, causing an advancement of monsoon over the Andaman Sea slightly before the normal date.
The onset of monsoon over the Kerala coast was predicted on June 1 last year but it was delayed.