India Meteorological Department (IMD) expects the South-West monsoon to advance into the South Andaman Sea, some parts of South-East Bay of Bengal and the Nicobar Islands by the weekend (May 18/19 or Saturday/Sunday) around the normal date. 

Upstream Maldives and Sri Lanka are already experiencing scattered to heavy showers and thunderstorms, the respective Met agencies said. The monsoon normally enters Maldives around mid-May and Sri Lanka five-six days thereafter. It may break over Lanka slightly earlier than normal by May 21. That should make the way clear for subsequent onset over Kerala too around the normal time. 

Late over Myanmar

On Monday, cyclonic circulations hovered over the Comorin region to Sri Lanka’s West and over South Interior Karnataka to its North. Thunderstorms and showers will give way to steady South-Westerly flows along Sri Lanka by the weekend around the same time as the monsoon breaks over the South Andamans. But Myanmar will have to wait longer for the first rains to arrive. 

Normally, the monsoon arrives first over Myanmar in the second week of May, followed by the Andaman & Nicobar Islands, Sri Lanka and Kerala over a fortnight. On Monday, the Myanmar national forecaster did not give any indication of the timing of the onset. But it expects a helpful low-pressure area to form over South-East Bay and adjoining South Andaman Sea next week. 

Pre-monsoon showers

Pre-monsoon thundershowers continue to last over many parts of the Peninsular India and adjoining East-Central India. Heavy to very heavy rainfall was reported from isolated places in Tamil Nadu and Telangana until Monday morning while it was heavy over Odisha, Karnataka, Rayalaseema and Kerala. This has put a lid on an oppressive heating trend at many places in these regions. 

A short-to-medium term outlook valid for three days from May 20 (early next week) said isolated to scattered light to moderate rainfall is likely over the Lakshadweep and Andaman & Nicobar Islands, the Western Himalayas, Northeast and South Peninsular India. Rainfall intensity may increase over Andaman & Nicobar Islands from Saturday (May 18) likely signalling the monsoon.