Climate Change

Mocha: Cyclone intensification may not be very high since it will be formed in heart of the Bay, say experts

Experts are treading cautiously about path Mocha will take; it depends on storm’s recurve, they say  

By Jayanta Basu
Published: Friday 05 May 2023
The likely places where Mocha could make landfall. Source: Tropical Weather Outlook report, IMD on May 5, 2023
The likely places where Mocha could make landfall. Source: Tropical Weather Outlook report, IMD on May 5, 2023 The likely places where Mocha could make landfall. Source: Tropical Weather Outlook report, IMD on May 5, 2023

Weather experts have stated that the intensification of Cyclone Mocha will likely not be very high as it will form in the central Bay of Bengal and will have less distance to traverse for a possible landfall compared to cyclones forming on the high seas.

This, even as the latest communication of India Meteorological Department (IMD), issued on the afternoon of May 5, 2023, has indicated that Mocha, to be generated on May 6, may turn into a ‘severe’ to ‘very severe cyclonic storm’ that will make landfall between May 12 and 13.

“As the cyclonic storm will be generated in central Bay of Bengal, the distance it gets to travel is not much compared to a cyclone generated in say, the Gulf of Thailand. Hence, not much intensification is expected,” K J Ramesh, former IMD director told this reporter.

Sunanda Bandopadhyay, a professor from Calcutta University who works on cyclones in the region, also expects the intensification will not be very high and will follow the pattern shown by earlier May cyclones in the area.

Path of the storm

Ramesh, Bandopadhyay and other senior experts are treading cautiously on the official prediction, with many pointing out that it is difficult to predict the likely path and landfall point till the low-pressure area gets fixed.

“Once the low-pressure area gets fixed, the likely path and other details can be predicted based on simulation with most models agreeing on the track,” Ramesh said.

GK Das, head of the weather division in IMD, Kolkata, reminded that during May, cyclones generally affect the coast stretching from Odisha to Myanmar; and pointed out that West Bengal is at risk too.

“The point of recurve is very important; the earlier it recurves, the more the probability of landfall in Myanmar; the later it recurves, Bangladesh and the adjoining Indian coasts will be more affected,” Pulak Roy Choudhury, a retired IMD official and cyclone expert, said.

“Even if the cyclone hits Bangladesh, it is expected that the coastal area of West Bengal in the southern part of the state will be affected with high winds and rainfall,” said another expert, pointing out that the projected Bangladesh landfall location is around 250 km away from the West Bengal border.

IMD GFS model indicates “nearly northeastwards movement towards Bangladesh coast and crossing over Bangladesh coast near 91.5 E (around the Chattogram area) around 13/000 UTC (May 13, 5.30 am Indian time)” and also indicates the possibility of “intensification up to very severe cyclonic storm (VSCS) category”.

Model NCEP GFS indicates “SCS (severe cyclonic storm) around May 10th over Andaman Islands, (will move) nearly northwards movement and crossing over Myanmar near 20.7N/92.4E (Sittwe, Myanmar) around 13/0900 UTC (May 13, 2.30 pm Indian time).

Another model ECMWF is indicating “intensification into cyclonic storm around 11th and north-northeastwards movement … crossing over Myanmar coast near 16.5N/96.5E (near Kala-ywa, Myanmar) around 12/1200 UTC (May 12, 5:30 am Indian time).

However, another model NCUM is indicating “west-northwestwards movement towards Tamil Nadu coast and emergence into southeast east central Arabian sea as a VSCS (very severe cyclonic storm) on 13th May”.

IMD points out that though “there is large divergence among various models wrt track … overall ECMWF & GFS group of models are indicating nearly northwards/north-northeastwards movement and crossing over southeast Bangladesh-South Myanmar coasts”.

“Nothing can be categorically said about the path till the low pressure is formed. But most models indicate Bangladesh and Myanmar as the possible landfall points,” Mrutyunjay Mohapatra, director-general of IMD, told this reporter.

The West Bengal government has already started preparations with the state chief secretary calling emergency meetings on Mocha.

“Though we do not how much impact West Bengal will have to bear, we are getting ready. We are preparing cyclone shelters and are also releasing about Rs 50 crore to the irrigation department for urgent work in vulnerable areas,” said a senior West Bengal government official on May 5.

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