A dust storm is a type of a windstorm that sweeps cloud of dust across an extensive area. Some meteorologists tend to differentiate between a dust storm and sandstorm. They argue that a dust storm consists of strong winds and pollutants blowing over an arid or drought-hit area. Whereas, a sandstorm mainly occurs in a desert composed of sand particles (WeatherNation, 2016). It is worth-mentioning that both of these storms are a category of windstorms and can be a result of a jet stream or thunderstorm. Since, the composition of sand and dust particles is distinct hence it needs to be analyzed to determine whether the winds blowing are a dust storm or sandstorm.
Karachi’s dust storm is a result of westerlies and easterlies
Given that Karachi is surrounded by arid areas in Balochistan in the west while Thar desert in the north east, it is difficult to determine whether these winds are dust storms or sand storms or even a combination of both. For convenience of our readers, we will call such winds ‘dust storms’ until a reliable research is published.
Dust storms, locally called Andhi which is a Urdu and Hindi word for dust-raising winds, are common in Karachi. The city experiences such winds two times in a year, one in the summer and one in the winter.
Westerly Dust Storm
- It originates from Balochistan and can influence the weather pattern of the city in any month but mostly in spring, summer and post-monsoon season.
- The one that hits the city in winter (or early spring) is on a much larger scale as it grips various countries though with less intensity winds, it mainly emerges from Iran or the Middle East and can go as far as India.
- Both of these winds are a part of western disturbance.
- It originates from the Thar desert in Pakistan and India, it usually affects the city when a monsoon depression from Gujarat or Rajasthan moves in a SSW direction towards Karachi in the month of May and June.
- It is a part of the monsoon season.
Westerly-Easterly Dust storm
- There have been documented cases where we have observed a blend of both dust storms.
- Usually, when a cyclone is making a landfall in the Indian state of Gujarat or Maharashtra in the pre or post monsoon season and if a western disturbance is present over Balochistan, a thunderstorm forms over eastern Balochistan that brings a strong dust storm to the city as it moves towards the cyclone.
List of dust storms in Karachi
Following is a list of some dust storms that occurred in the city;
- On September 1, 1926, A windstorm hit Karachi but not much is known about this storm.
- On May 31, 1986, A blinding dust storm hit the city, it had winds upto 67 mph (108 km/h) while visibility reduced to near zero.
- On July 4, 1994, a windstorm generated by monsoon low pressure system killed 26 people in the city.
- In August 1995, dust storm due to a monsoon low occurred in the city that reduced the visibility to almost zero.
- On June 23, 2007, a massive dust storm with winds upto 69 mph (111 km/h) hit the city followed by a heavy downpour. A total of 200 people lost their lives on that day. The dust storm was due to a monsoon depression from central India that intensified into Cyclone ‘Yemyin’ in subsequent weeks.
- On February 22, 2008, a winter dust storm struck the city which reduced the visibility to merely 500 metres, the dust storm was due to the westerly winds that were coming from the desert regions of Balochistan.
- In Novemeber, 2010, a combination of westerly wind and remnants of Cyclone ‘Jal’ brought dusty winds in the city.
- In March, 2012, a weak westerly wave brought a mild dust storm of 65 km/h to the city.
- On April 15, 2019, a dust storm due to a western disturbance brought gale-force winds of 85 km/h to 90 km/h.
- In May 2020, an intense dust storm gripped the city at night followed by light drizzle due to a western thunderstorm and nearby Cyclone ‘Nisarga’.
- In May 2021, due to a western thunderstorm and nearby Cyclone ‘Tauktae’ brought severe dust storm to the city.