The story thus far: On December 5, Cyclone Michaung (pronounced mig-jaum) made landfall over Nellore in Andhra Pradesh as a super-cyclonic storm. A day earlier, the climate system had produced 150-200 mm of rain in north Tamil Nadu.
How did the cyclonic storm take form?
On November 29, the India Meteorological Department (IMD) recognized a well-marked low strain space within the southwest Bay of Bengal. It was anticipated to grow to be a despair by November 30, a deep despair on December 2, and ultimately a cyclonic storm by December 3. Thereafter, the IMD forecast that the system would transfer north in the direction of coastal Andhra Pradesh, bringing rain and sturdy winds to areas in north Tamil Nadu on December 3 and 4, whereas travelling parallel to the latter’s coast. It was lastly anticipated to cross over land between Nellore and Machilipatnam as a cyclonic storm, with 80-90 km/hr winds gusting to 100 km/hr.
High tides at Marina seaside on December 1, 2023, earlier than the storm was anticipated to hit the Chennai coast.
| Photo Credit:
Ragu R./The Hindu
On December 1, the Joint Typhoon Warning Centre (JTWC), a joint U.S. Air Force and Navy command, upgraded the chance of cyclone formation to ‘high’. By December 2, the despair had intensified right into a deep despair, as anticipated, whereas it was round 500 km southeast of Chennai and transferring at round 17 km/hr. It was anticipated to strategy Chennai inside two days despite the fact that, quickly after, the system additionally appeared to gradual its northward progress. By the top of the day, it had come to inside 400 km of Chennai, nonetheless as a deep despair, and induced rain over the town’s south.
At this time, the JTWC knowledge indicated that the ocean floor temperature was round 28 levels C. More than 27 levels C is beneficial for cyclogenesis, the method by which cyclones are created and intensify.
By the morning of December 3, the system had grow to be cyclonic.
Why was Michaung named so?
In 2000, a panel of the World Meteorological Organisation along with members of the United Nations Economic and Social Commission ready the record of names of tropical cyclones within the Bay of Bengal and the Arabian Sea, to be given from the September 2004 season. The title of every cyclone is picked from this record and cycles by every nation’s suggestion.
For instance, after Michaung (by Myanmar), the following 5 cyclones will probably be known as ‘Remal’ (Oman), ‘Asna’ (Pakistan), ‘Dana’ (Qatar), ‘Fengal’ (Saudi Arabia), and ‘Shakhti’ (Sri Lanka).
How did Cyclone Michaung proceed?
As Cyclone Michaung approached north Tamil Nadu, Chennai and the encompassing districts of Kancheepuram, Thiruvallur, and Chengalpattu started to obtain rain. The State authorities declared a public vacation in these areas on December 4, later prolonged to December 5, after the IMD forecast heavy showers.
By the night of December 3, Cyclone Michaung was 200 km from the town, roughly east, and had slowed to round 8 km/hr. By December 4 morning, and opposite to expectations, it had moved extra westward than northward, bringing it inside 150 km of the town, dumping a big amount of water as rain along with sturdy winds gusting as much as 80 km/hr.
Railway tracks at Egmore Railway Station have been submerged after the arrival of Cyclone Michaung close to Chennai, December 4, 2023.
| Photo Credit:
Ragu R./The Hindu
Cyclone Michaung continued to stay near Chennai on December 4 night, with many areas within the metropolis reporting receiving greater than 120 mm of rain within the earlier 24 hours, and some greater than 250 mm. There have been a number of experiences of localised flooding and individuals stranded in locations the place the water refused to empty, along with a city-wide energy minimize.
Nonetheless, Chennai managed to fare higher than it did after the 2015 rains due to managed launch of water from the Chembarambakkam reservoir. Eight years in the past, an uncontrolled launch of a giant quantity had flooded the town.
Rains in Chennai lastly ceased within the wee hours of December 5 as Cyclone Michaung resumed its northward journey.
Why did Cyclone Michaung intensify?
On December 4, the cyclonic storm intensified right into a super-cyclonic storm. Such intensification occasions are a supply of uncertainty in cyclone fashions as a result of they alter the storm’s future course.
Tropical cyclones are ‘engines’ that use a heat sea floor as ‘fuel’. This is why they kind near the equator (however seldom on the equator itself as a result of the spinning power, known as the Coriolis power, is lowest there).
As air strikes over such a heat sea, it additionally turns into hotter and laden with moisture, and begins to ascend. In the method, it turns into cooler, which condenses the vapour and types clouds. Condensation releases warmth, which makes the air lighter and causes it to ascend additional. As it does, the encompassing air strikes in beneath, creating the floor winds related to cyclones.
This (simplified) course of is the rationale local weather change – and the ensuing sea-surface warming, since these giant water our bodies take in the overwhelming majority of the warmth of world warming – has been conducive to cyclone intensification.
Vehicles struggling to cross the submerged Poonamallee High Road after heavy rains in Chennai, December 4, 2023.
| Photo Credit:
Ragu R./The Hindu
The intensification can also be larger if the cyclone spends extra time over the water earlier than landfall, as Cyclone Michaung did off the coast of north Tamil Nadu.
Why does intensification matter?
Cyclones draw warmth from the ocean and transfer it to the higher environment, the place winds carry it to the earth’s poles and heat them. An intensifying cyclone will do that extra powerfully.
A examine revealed in May 2020 discovered that tropical cyclones with wind speeds upwards of 185 km/hr had grow to be 15% extra possible since 1979.
In 2021, Cyclone Yaas took benefit of an Arabian Sea floor temperature of 32 levels C for a number of days earlier than slamming into Gujarat as a particularly extreme cyclonic storm. Roxy Mathew Koll, scientist on the Indian Institute of Tropical Meteorology, Pune, had mentioned on the time that “rising ocean temperatures in both [the Arabian Sea and the Bay of Bengal] are assisting … cyclones in their ‘rapid intensification’ process. Otherwise, we don’t see a significant increase in the number of cyclones over the Bay of Bengal as we see in the Arabian Sea.”
Cyclone Michaung’s personal intensification was additionally assisted by the Madden-Julian oscillation (MJO), amongst different components, in response to a December 3 advisory from the Regional Specialised Meteorological Centre – Tropical Cyclones, New Delhi.
The MJO consists of a ‘pair’ of climate anomalies that transfer eastward around the globe as soon as each one to 2 months. The main aspect imposes dry climate whereas the trailing aspect imposes moist (wet) climate. The advisory mentioned that on December 3, the MJO was in part 4, close to Cyclone Michaung, indicating beneficial situations for rain formation.
A person runs to security as high-speed winds as a result of Cyclone Michaung lashed the Suryalanka seaside in Bapatla district, December 5, 2023.
| Photo Credit:
Okay.V.S. Giri/The Hindu
Aside from complicating forecast fashions, cyclone intensification permits these storms to make landfall with extra power, transfer additional inland, survive longer, and prolong their on-ground devastation to beforehand ‘inaccessible’ areas.
What was Cyclone Michaung’s destiny?
According to native experiences, Cyclone Michaung crossed over land simply south of Bapatla district in Andhra Pradesh from 12.30 pm on December 5 as a super-cyclonic storm. It introduced heavy rain and winds with a sustained velocity of 90-100 km/hr because it crossed over over a interval of three or so hours, within the course of uprooting timber and electrical poles.
As of 9 am on December 6, its results on the bottom — typically as a results of poor infrastructure — had led to the deaths of 12 individuals.
Based on radar knowledge as much as 3.30 pm on December 5, the IMD reported that the storm had accomplished landfall and “lay centred … over south coastal Andhra Pradesh, about 20 km west-southwest of Bapatla and 45 km north-northeast of Ongole”.
An hour later, an IMD bulletin mentioned the storm system was transferring northward at 11 km/hr whereas weakening right into a cyclonic storm over the following couple hours. This is a direct results of the cyclonic ‘engine’ dropping its supply of ‘fuel’ — a heat water-body beneath. The State’s north coast was forecast to expertise rain with winds of 50-60 km/hr on this time.
By 6 pm on December 6, the IMD had anticipated the storm to devolve right into a well-marked low strain space.
