A history of Arabian Sea cyclones

Published November 2, 2014
NASA satellite photo shows Tropical Cyclone Nilofar in the Arabian Sea.
NASA satellite photo shows Tropical Cyclone Nilofar in the Arabian Sea.

Scientists say that due to its small size, strong cyclones in the Arabian Sea are generally more rare than in other basins. On average one to two tropical cyclones form over the Arabian Sea each year and few of these storms are intense enough to be classified as very severe or super cyclonic storms. However, the UN’s Intergovernmental Panel on Climate Change now reckons that in an increasingly warmer world, the frequency of cyclones will stay the same or decrease while their average intensity goes up. Their latest scientific report (Assessment Report 5 which was released earlier this year) states: “Tropical cyclone numbers are unlikely to increase, but cyclone maximum intensity is likely to increase in the global average, meaning increased maximum precipitation and winds”.

As Cyclone Nilofar (named by the Pakistan government) heads towards the Western Indian and Southern Pakistani coastlines, it is developing into a “very severe cyclonic storm”. “Nilofar” in Persian means a lotus or water lily; certainly an innocuous name for what is looking to be a very destructive storm.

According to Dr Qamar-uz-Zaman Chaudhry, one of Pakistan’s top climate change experts and former Director General of Pakistan’s Meteorology Department (PMD), “While one cannot say that a particular cyclone is the result of climate change, general data now indicates that the overall intensity of cyclones is increasing because of climate change.” When it comes to the Arabian Sea, “the facts remain that each year before the onset of the monsoon (15 April to 15 July) and also after its withdrawal (15th September to 15th December), there is always a distinct possibility of a cyclone storm to develop in the north Arabian Sea”. He further explains that “tropical cyclones are classified according to the maximum winds which accompany them as indicated by the following: depression — winds up to 33 knots, cyclonic storm — winds from 34 to 47 knots, severe cyclonic storm — winds from 48 to 63 knots, very severe cyclonic storm — winds of 64 knots or more”.


Experts warn that climate change is increasing the intensity of cyclones


He points out that the distinguishing property of the cyclonic storm is the onslaught of tidal waves that often accompany the storms along with strong sustained winds and torrential rain. “These giants kill in three ways — by coursing heavy to very heavy continuous downpour leading to floods, strong to very strong sustained winds and tidal waves”.

Accurately forecasting the passage of the cyclonic storm into coastal areas is extremely important to save lives. For that, the PMD has set up an extensive Marine Meteorology and Tropical Cyclone Warning Centre (TCWC) in Karachi to issue warnings to fishing boats, commercial ships and Pakistan Navy vessels in the Arabian Sea, Gulf of Oman and Persian Gulf. With Cyclone Nilofar heading to make landfall, fishermen have been advised not to venture into the open sea and those already at sea have been told to come back to shore. Weather officials in Pakistan are hopeful that the cyclone will weaken before it hits the coast, although it could still bring strong gusty winds and rains.

In recent years, most cyclones developing in the Arabian Sea have headed towards Oman or the Indian state of Gujarat, mostly bypassing Karachi which is good news for the mega city as it a densely populated urban centre of around 20 million people and a direct hit by a cyclone would be catastrophic.

According to meteorological data about cyclonic storms in the north Arabian Sea dating back to the last 100 years, a number of cyclonic storms have struck Pakistan’s coastal areas, some wreaking considerable devastation. The more recent ones have been Cyclone Yemyin (2007), which made its landfall along the Makran coast near Ormara and Pasni in Balochistan Province and Cyclone Phet (2010), which made its landfall along the Sindh coast (between Karachi and Keti Bunder). Cyclone Phet killed around 15 people, while Cyclone Yemyin killed 730 people and affected the lives of two million people in Pakistan, making it the third deadliest cyclone in the history of the country.

In June 2007, Cyclone Gonu was the most intense Arabian Sea storm on record, making landfall in Oman, then in southern Iran. Cyclone Gonu, which was the first Category 5 equivalent storm, claimed 100 lives in Oman, Iran and the United Arab Emirates and was responsible for $4 billion in damage. Category 5 is the most destructive storm with maximum wind speeds of over 137 knots in the hurricane classification system used mostly for tropical cyclones in the Atlantic Ocean and in the Pacific Ocean; the North Indian Ocean uses the tropical cyclone intensity scale explained earlier.

The most destructive cyclone in recent years to hit Pakistan has been Cyclone 2A, which slammed into Pakistan near Karachi in May 1999 as a strong Category 3 equivalent storm, killing 6200 people in the country. At the time, no attempts had been made to evacuate residents before the cyclone made landfall.

Published in Dawn, Sunday Magazine, November 2nd, 2014

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