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Cyclone: Cyclonic storm Ditwah did not hit the Indian coast, which was expected. However, this storm killed more than 300 people in Sri Lanka. But IMD has given the real reason for it not hitting the Indian coast.
Sri Lanka and its northern part Jaffna is located immediately below India i.e. in the southern part. Cyclone Ditwah was wreaking havoc here for the last three days. Due to which more than 300 people died. However, after Sri Lanka, it was the turn of the southern states of India. The weather department also had a catastrophic forecast. It was expected to hit the coast of Tamil Nadu first, then Tamil Nadu-Puducherry. But instead of touching the Indian coast, this storm weakened while passing parallel to it. According to IMD, the center of the storm was at least 25-80 km away from the Tamil Nadu-Puducherry coast. It became weak in the northern direction only in the Bay of Bengal. A major disaster was averted due to the absence of landfall on the Indian coast. But it is important to know why the storm did not hit? Let us know the scientific reason.
IMD Director General M Mohapatra said that the storm crossed Sri Lanka on 29 November. After this, India gradually started moving in the northern direction. However, in just 24 hours it intensified again in the Bay of Bengal, but then its speed decreased and it started moving in the north-northwest direction at a speed of 5 kilometers per hour. This cyclonic storm did not hit the coast and its center remained 80 km away from the northern coast of Tamil Nadu (150 km south-east of Chennai). Main reasons-
- Increasing Wind Shear: Due to the difference in the direction and speed of the upper winds, the upper part of the storm (cloud system) got separated from the lower part. Due to this, the structure of the storm started disintegrating and the strength decreased. IMD said that wind shear reached above 20 knots, which was a major reason for the weakening of the storm. Actually, the main function of wind shear is to weaken the cyclonic storm. This separates the upper part of the storm from the lower part.
- Cooler Sea Surface Temperatures: Sea temperatures in the south-west part of the Bay of Bengal dropped to 28-29°C, while the storm needs temperatures above 30°C to remain strong. The cold water weakened the storm by not giving it energy.
- Track and direction of the storm: The nature of the storm was towards the north, which remained parallel to the coast. According to IMD forecast, it passed 50 km away from Chennai and became a weak depression 25 km away from Puducherry. This resulted in heavy rainfall (100-150 mm at some places) in Tamil Nadu, but due to no landfall, the loss of life and property was less. Due to this, three people died in rain-related accidents.
Many storms had changed paths before
Like previous cyclones (such as Ogni of 2006 or Depression of 1993), the track of ‘Ditvaha’ also ran parallel to the Tamil Nadu coast. IMD issued forecast that the probability of landfall is low. Therefore, red alert was issued in the coastal districts. India helped Sri Lanka, but due to its preparations, it allowed the storm to pass without much damage.
