Explained: Why cyclones hit the east coast in October, and how they are predicted

Conditions in the Bay of Bengal explain why Titli struck in same month as Phailin and Hudhud, but scientists face hurdles in accurate prediction.

Written by Sampad Patnaik | Bhubaneswar | Updated: October 15, 2018 9:16:10 am
Why cyclones hit the east coast in October, and how they are predicted Boats being moved to a safer place after Titli struck Ganjam. (Photo: Reuters)

Last week, Cyclone Titli became the third major cyclone to hit the Odisha-Andhra coastal zone in the last five years, all in October. What explains the similar timing, and how effective are the mechanisms for prediction and disaster mitigation?

Season & frequency

Cyclones have always been frequent in the region. What has risen is is the “frequency of intense cyclones in the area”, say scientists with IIT-Bhubaneswar’s School of Earth, Ocean and Climate Science, citing their observations on the Bay of Bengal. Adjacent to the northwest Pacific, which is one of the world’s most active basins for typhoons, the Bay of Bengal receives the remnants of major landfalls in the Philippines, China and South Asia. From these places come low-pressure systems that develop into a monsoon depression or a cyclone. The reason that cyclones such as Titli, Phailin (2013) and Hudhud (2014) typically strike in October is that wind shear — the difference within wind speeds and direction at two different levels — is low during this time; low wind shear, when combined with surface sea temperatures greater than 26°C, raises the likelihood of cyclones. In monsoon season, cyclones are rare because of high wind shear.

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A group of people relocate to safer places as Cyclone Titli hits Barua village, in Srikakulam. (PTI Photo/File)

Hard to predict

The Odisha government has come under criticism for not being able to accurately anticipate the landfall of Cyclone Titli or the very heavy rainfall that brought large areas under water. Scientists say prediction is difficult because of budgetary and meteorological factors. In the Atlantic basin, the US has dedicated aircraft that fly directly into the clouds to study moisture levels and gather various data on cyclone profile. For Indian cyclones developing over the ocean, scientists say they have to largely rely on satellite images (a top view) that reveals little data on moisture content and intensity. Indian scientists get a more detailed picture only when a cyclone is 300-400 km from the coast, which reduces preparation time; Cyclone Titli was additionally hard to read because it turned into a recurving cyclone (it changed direction). India acquires storm prediction models from the US and Europe but lacks the resources to upgrade the models regularly, IIT-Bhubaneswar scientists say.

Read | Women rush to name newborns after cyclone ‘Titli’ in Odisha

Cyclone Titli weakens, heavy rain and flood batters Odisha Flooding was reported in many parts of Ganjam, Gajapati and Rayagada district. (PTI photo/File)

How evacuation is done

Researchers classify evacuation exercises as preventive, vertical, and shelter-in-place. In preventive (or horizontal) evacuation, the impact area is meant to be completely evacuated, but this is a measure rarely taken in India because of poor roads and inadequate public transportation. Also, poor people rarely have the resources to find alternative accommodation. Shelter-in-place evacuation involves fortification of existing houses and community buildings, which again required financial resources. In vertical evacuation, people are directed to specially designed buildings within the impact area. This strategy was largely followed during Cyclone Titli.

Researchers classify evacuation exercises as preventive, vertical, and shelter-in-place. (PTI photo/File)

Special Relief Commissioner Bishnupada Sethi, Odisha’s senior-most disaster management official, said over a thousand multipurpose cyclone shelters were readied. Activists on the ground, on the other hand, told The Indian Express that the government does not have adequate multipurpose cyclone shelters. “Many villages in Ganjam and Gajapati were evacuated into school and college buildings, which were then designated storm shelters,” said activist Rabindra Patra.

An estimated number of 60 lakh people have been reported to be affected by the calamity in Odisha. (PTI Photo/File)

Evacuation efficacy

The government claimed around 3 lakh people were successfully evacuated during Cyclone Titli. However, widely held parameters of success in disaster management, such as number of evacuees, are “misleading”, say researchers such as Biswanath Dash of BITS Pilani. He said talk of the number of evacuees masks actual vulnerable populations and whether the government was able to identify and safeguard them. “During Titli, Hudhud or Phahilin, lives were saved because, unlike the 1999 Supercyclone, there was no storm surge,” said Dash. A storm surge is an abnormal rise of water generated by a storm. According to Dash, “fewer casualties during Phailin and Hudhud were because of the limited severity of these cyclones than effective disaster planning”.

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