Haboob: Dust Outflow on August 24
The dust event experienced in Doha in the late afternoon of August 24th, 2016
This is a type of dust storm, called Haboob, caused by strong winds flowing downward (downdraft) and outward (outflow) from within a thunderstorm that develops over dry terrain with loose topsoil. In Qatar, the strongest Haboobs form with the first rain of the season as the soil is dry and hasn’t been compacted by previous rain. This type of Haboob tends to be on the order of 50-150 kilometers in diameter, and associated with a single large dying thunderstorm cloud. The dust making up the Haboob is typically from within the area and can be lifted as high up as 1,500 - 2,500 meters. The average Haboob tends to be short-lived, on the order of a few hours, and the dust settles quickly after the passage of the gust front (area of strongest wind speeds.)
In the early afternoon hours of 24 August a strong Cumulonimbus cloud and associated thunderstorm formed over Al Guwayriyah and Al Shahaniyah. Rain was detected by Qatar Meteorology Department (QMD) radar around 2 p.m. local time. The continued updraft of hot air into the storm resulted in the evaporation of rain within the cloud, quickly cooling the air within its core. The cold air sank and a strong downdraft developed pushing outward from the southern base of the cloud, picking up particulates and forming a semi-circular “wall of dust” moving outward from the area under the cloud. This Haboob front passed over the northern parts of Doha around 3 p.m.
Haboobs are very difficult to forecast and meteorologists rely on a now-casting approach to disseminate information to the public. QMD provided a general forecast of thunderstorms and downdrafts in the morning of the 24th and followed-up with live tweets as the thunderstorm developed and the impaired visibility impacted Doha and the surrounding areas. The dust in these storms can contain inhalable particulates, biological pathogens and heavy metals, depending on the storm’s origin. These negatively impact air quality and as such people should seek shelter indoors until such an event passes.
Fun Fact: Haboob is derived from the Arabic word (هَبوب - habūb) which means strong blowing wind and dust. The term has been used by meteorologists for decades to differentiate between these events and synoptically driven dust storms. Haboob is a type of dust storm, but not all dust storms are Haboobs!