Why cyclone Michaung headed to Andhra coast

Subject : Geography

Section: Physical geography

Context: Cyclone Michaung, headed to the Andhra coast

More about the news

Tropical Cyclone Michaung is anticipated to make landfall on the Andhra Pradesh coast in Bapatla district, between Nellore and Machilipatnam, on Tuesday morning (December 5), as confirmed by the India Meteorological Department .
The storm, located approximately 80 km southeast of Nellore and 120 km north-northeast of Chennai as of 5:30 pm on Monday, is moving northward along the Andhra Pradesh coast.
Michaung has already brought heavy rainfall to various regions in Tamil Nadu, parts of Andhra Pradesh, and southern Odisha.
The occurrence of such a high-intensity cyclone in December is unusual, as storms in the North Indian Ocean during this period typically don’t reach such destructive intensities.
Initially classified as a ‘tropical cyclone,’ Michaung was upgraded to the status of a ‘severe’ storm on Sunday, featuring wind speeds ranging from 88 kph to 166 kph—an uncommon intensification for December cyclones, attributed to above-normal heat index values off the southern Andhra Pradesh coast.

Some facts about Indian tropical storms:

Climatologically, the North Indian Ocean basin, encompassing the Bay of Bengal and the Arabian Sea, experiences the development of approximately five cyclones each year. Of these, an average of four cyclones develop over the Bay of Bengal, while one typically forms over the Arabian Sea.
Cyclones occurring in the Arabian Sea often achieve higher intensities, posing an increased risk of causing widespread damage.
The North Indian Ocean basin is most susceptible to cyclone development during the pre-monsoon months (April-June) and post-monsoon months (October-December).
Cyclones formed in May and November tend to reach higher intensities compared to storms originating at other times due to favorable ocean conditions.

How are Cyclones Classified

How Storm intensification happen:

Tropical cyclones are fueled by ocean heat in addition to other factors.
Ocean temperatures of 26 degrees Celsius or more, prevailing at depths between 50 metres and 100 metres, are conducive for cyclogenesis, which refers to the processes that lead to the development and strengthening of a cyclone.
Warm oceans contribute to a cyclone’s rapid intensification while at sea.
An oceanographic parameter called the Tropical Cyclone Heat Potential (TCHP) is considered an important factor in cyclone genesis, intensification, and propagation.
The intensification process of tropical cyclones is a complex phenomenon influenced by various favorable atmospheric conditions.
These include boundary layers (the fluid layer adjacent to a bounding surface), wind shear (changes in wind direction and/or speed over a vertical or horizontal distance), convection (the transfer of heat within a fluid), Rossby waves (which occur in rotating fluids), upper ocean circulation, and air-sea interaction.
The interaction of these factors contributes to the development and strengthening of tropical cyclones.

What is landfall of a cyclone:

Landfall occurs when a tropical cyclone moves from a position over water to coming onto land.
According to the IMD , a tropical cyclone is considered to have made landfall when its center, or eye, crosses the coast.
The “eye” of a cyclone is a zone of relatively calm weather situated at the center of the storm, characterized by light winds, clear or partly cloudy skies, and reduced precipitation.
Within the eye, winds are gentle and variable, often accompanied by clear or partially cloudy skies.
The size of the eye can vary widely, ranging from a few kilometers to over 50 kilometers in diameter in larger cyclones.
During landfall, the outer bands of the storm may have already reached the coast, bringing strong winds, heavy rain, and storm surge.
Landfall signifies the official moment when the cyclone reaches the land.
It’s important to note that landfall is distinct from a ‘direct hit,’ which occurs when the core of high winds (or eyewall) comes onshore while the center of the storm may remain offshore.
Cyclones lose their intensity once they move over land because of sharp reduction of moisture supply and increase in surface friction.