Heavy to very heavy rainfall has been reported at isolated places over Tamil Nadu and Rayalaseema on Sunday while it was heavy at isolated places over Kerala and coastal Andhra Pradesh as cyclone ‘Michaung’ over the South-West Bay of Bengal steamed in at a location 230 km to the east-south-east of Chennai and 250 km straight to the east of Puducherry in the afternoon.

Viewed from the Andhra Pradesh coast, the cyclone lurked at a distance of 350 km south-east of Nellore; 460 km south-south-east of Bapatla; and 480 km south-south-east of Machilipatnam. It is expected to move to the West-Central Bay by forenoon of Monday and intensify further into a severe cyclone, India Meteorological Department (IMD) said. Earlier, the IMD had upgraded the outlook for ‘Michaung’ to that of a severe cyclone with maximum sustained wind speeds of 90-100 kmph gusting to 110 kmph as it barrels over the south coastal Andhra Pradesh coast between Nellore and Machilipatnam on Tuesday morning.

Crucial MJO wave 

The intensification of the cyclone as it approaches the coast is thanks to the presence of a helpful Madden-Julian Oscillation (MJO) wave. The US Joint Typhoon Warning Centre is of the view the system would not have intensified beyond a depression without the handy support from the MJO wave. It periodically traverses upper levels of the atmosphere and sets up lower pressure, ascending motion of air and moisture build at the ground level. The wave has been associated with formation of low-pressure areas/cyclones and even monsoon onsets under its footprint. 

Rain for TN, Puducherry

Presence of the MJO wave aside, the cyclone is seen as getting buoyed by fortuitous strong easterly bursts generated by a ridge (high-pressure area with clockwise motion of air) that sits over North-East Bay of Bengal. IMD rainfall predictions indicate light to moderate rainfall at most places over north coastal Tamil Nadu and Puducherry with heavy to very heavy rainfall at a few places on Sunday. It would be isolated heavy to very heavy rainfall on Monday before reducing in intensity. 

Andhra Pradesh, Odisha

Over South Coastal Andhra Pradesh, it would be light to moderate at most places with heavy to very heavy rain at a few places on Monday. On Tuesday, it would turn heavy to very heavy rainfall with extremely heavy falls at isolated over Coastal Andhra Pradesh and Yanam on Monday and Tuesday. Isolated heavy rain is likely over North coastal Andhra Pradesh on Wednesday. As for Rayalaseema, it would be light to moderate at most places with isolated heavy to very heavy rain on both Sunday and Monday. 

High winds warned of

The fiercest winds from the cyclone would prevail over the West-Central Bay as squally with speeds reaching 55-65 km/hr gusting to 75 km/hr on Sunday before ramping up gradually to gale wind speeds reaching 70-80 km/hr gusting to 90 km/hr by the evening. Wind speeds are expected to escalate to 80-90 km/hr gusting to 100 km/hr from Monday morning and to 90-100 km/hr gusting to 110 km/hr from the evening to Tuesday noon as the projected severe cyclone makes landfall.

Regeneration prospects

A remnant of the cyclone is seen as heading East-North-East along the coast and bring light to moderate rainfall at most places over Odisha with isolated heavy rain over south coastal and adjoining south interior Odisha from Monday to Wednesday with isolated very heavy rain over the same region on Tuesday. Some models are seeking to put a watch on the remnant for any signs of regeneration. But others are of the view it may not evolve to any appreciable strength since the waters are cooler over the North Bay along with the high wind shear (change in wind direction and strength with height), which can kill a developing storm.