A possible cyclone could be brewing in the Bay of Bengal

But the intensity and track of the system remain uncertain as weather models differ in their forecasts
A possible cyclone could be brewing in the Bay of Bengal
A screengrab of Windy.com on October 17, showing the formation of a cyclone on October 20 in the Bay of Bengal
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The eastern coast of India may be impacted by a cyclonic storm in the next week. But the intensity and track of the system remains uncertain at this point as various weather models differ in their forecast of these parameters. 

The third low pressure system of the post monsoon cyclone season for the North Indian Ocean comes days after the second depression crossed the south Andhra Pradesh and north Tamil Nadu coasts on October 17, bringing heavy rainfall for the regions.

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A possible cyclone could be brewing in the Bay of Bengal

This shows that the sea surface temperatures and other environment conditions such as vertical wind shear in the region may be conducive for the genesis of cyclonic storms. The period from October-December is generally considered to be cyclone season for the North Indian Ocean region.

In its tropical weather outlook on October 17, the India Meteorological Department (IMD) said that “a fresh upper air cyclonic circulation is very likely to form over North Andaman Sea around 20th October. Under its influence, a low-pressure area is likely to form over central Bay of Bengal around 22nd October. Thereafter, it is likely to move northwestwards and intensify further.”

The IMD also gives a low probability of ‘cyclogenesis’ (formation of depression) around 6-7 days from October 17. These probabilities may change as the formation of the storm system comes closer.

While the earlier two systems did not intensify into a cyclone, the third system might. The Windy weather analysis and visualisation platform on October 17 showed the formation of a low-pressure area in the North Andaman Sea on October 20, with data from the Global Forecasting System (GFS) of the United States.

The GFS further shows the intensification of the low-pressure area into a depression on October 21 and strengthening into a cyclone by October 22.

On the other hand, when Windy uses data from the European Centre for Medium Range Weather Forecasts (ECMWF), it shows the formation of a weak depression on October 22. This difference between different forecasting systems shows that the intensity and track of the cyclonic storm still remain uncertain.

IMD indicated cloud top temperatures (CTTs) of -70°C to -80°C in the South Bay of Bengal and Andaman Sea in its tropical weather outlook.

CTT indicates the temperature of the top of the cloud measured using infrared bands from weather satellites and informs about the possibility of formation of clouds and rain.

A CTT of -70°C to -80°C is generally considered conducive for the formation of strong convection that can regenerate storms and rainfall.

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