The Climate Prediction Center of the US National Weather Service has signalled elevated chances for storm development over both the Bay of Bengal and the Arabian Sea, in line with the climatological pattern of May when the northern Indian Ocean traditionally turns more active ahead of the onset of south-west monsoon.
MJO to likely set it up
Fuelling the outlook is an advancing phase of the Madden–Julian Oscillation (MJO) now traversing the western Indian Ocean and the Arabian Sea. The MJO, a vast pulse of winds, pressure, cloudiness and rainfall that circles the tropics from west to east every 30 to 60 days, often acts as a trigger for low-pressure areas, depressions, cyclones and even the onset of the monsoon itself.
Unusual westerly winds
The CPC has also pointed to an unusually strong burst of lower-level westerlies along the Equator, a development considered favourable for storm formation on both sides of the equatorial belt. The agency has identified the period between May 13 and 19, and the opening days of the following week, as a potentially conducive window for storms to organise over the Bay and the Arabian Sea.
ITCZ lies in wait
Attention will now turn to whether these evolving systems can pull the Intertropical Convergence Zone (ITCZ) into position and help trigger the monsoon’s first advance over the Andaman and Nicobar Islands, customary gateway for the monsoon into the Indian region. The ITCZ, a near-continuous belt of low pressure girdling the globe, migrates seasonally with the Sun and governs the rhythm of monsoon circulations across the tropics.
Intense heating
At the same time, the CPC has warned of an increased likelihood of above-normal pre-monsoon temperatures and episodes of extreme heat across parts of contiguous north-west India and adjoining Pakistan, with daytime temperatures likely to exceed 43°C in isolated pockets. Such intense land heating is a crucial precursor for the monsoon, sharpening the pressure and temperature contrast between the subcontinent and the surrounding seas, thereby helping draw the moisture-laden monsoon currents inland.
Isolated heavy rain
As if on cue, the India Meteorological Department (IMD) has forecast isolated heavy rainfall over the meteorological subdivisions of Tamil Nadu, Puducherry and Karaikal as well as Kerala and Mahe during the next seven days, with South Interior Karnataka likely to receive intense spells today (Friday).
Thunderstorms, lightning
The IMD has also warned that isolated to scattered thunderstorms accompanied by lightning and gusty winds reaching 30-50 km/hr could intensify across Tamil Nadu, Puducherry and Karaikal; Kerala and Mahe; Lakshadweep; and Interior Karnataka over the next five days. Similar activity is expected over Coastal Andhra Pradesh and Yanam, Rayalaseema and Telangana during the next four days, while Coastal Karnataka may remain under the influence of unsettled weather through Friday and Saturday.
Pre-monsoon dynamics
The expanding convective activity across the South Peninsula comes amid growing indications of strengthening pre-monsoon dynamics over the adjoining seas, with atmospheric conditions increasingly turning favourable for organised rain-bearing systems ahead of the seasonal monsoon advance.
Published on May 8, 2026