After a long pause, conditions have now become favourable for the advancement of southwest monsoon over the North Andaman Sea and the entire chain of the Bay of Bengal (BoB) Islands. Moist southwesterly winds, cloud cover and rainfall parameters are conducive for covering the region with a monsoon stream. After advancing over the Andaman Sea, it is likely to travel to some more parts of BoB within 72hours.
Earlier, southwest monsoon had made on time start over the extreme South Andaman Sea and the Southernmost Island of the chain, Nancowry on 19th May 2023. Very unusual for a monsoon to get stuck for more than 10 days over that part of the ocean. The complete chain of islands was rain starved so far during the rainiest month of pre monsoon. Andaman & Nicobar Islands have registered a large deficit of 67% rainfall and recorded only 138.3mm against the normal of 424.2mm, between 01st Mar and 29th May 2023. The month of May remained the poorest of the season and logged a shortfall of nearly 75% rainfall over the major islands.
Cross equatorial flow has picked up over Southeast BoB and the winds have become stronger. Cloud cluster is also seen along the coast of Thailand and Myanmar and extends to the Andaman Sea. The entire stretch of islands has received decent moderate showers in the past 24hr, after witnessing a dry spell for over one week. Long Island (56mm), Port Blair (12mm), Car Nicobar (29mm) and Maya Bandar (5mm) were the rainfall amounts during the past 24hr.
The monsoon progress is a bit slow. The normal date of arrival for this region is the 22nd of May. Last year, it was before time by a good margin. Going by the normal, the southwest monsoon reaches Sri Lanka and deep into Myanmar on the 26th of May. Monsoon March is likely to be slow and may still take more than one week to reach mainland Kerala.
