Image: De Krans Wines (Stormchasing SA)
It is very difficult to tell from the images alone whether this was indeed a tornado. What is certain that it is a very nice specimen of a funnel cloud. In meteorological circles there is a difference of opinion as to whether a funnel cloud must touch the ground before it is classified a a tornado. Others are of the opinion that it does not have to touch the ground. Be as it may credit must go to all those who captured images of this event. Great observation and a good example of weather awareness.
We cannot ignore the fact that tornadoes do occur more regular in South Africa then some would think. We must however distinguish between severe storms associated with extensive wind damage and the occurrence of a tornado.
South African tornadoes typically arise with very hot air masses and severe thunderstorms. The number of tornadoes in South Africa may be well under reported. One such incident is an F3 tornado event on 21 October 1999, 50km south of Johannesburg. Investigators noted: "It is alarming that an event of such magnitude would have gone unnoticed or ignored, especially in view of its closeness to South Africa's largest metropolitan area."
According to the South African Weather Service, most tornadoes have been observed in the Gauteng, the Free State, KwaZulu-Natal (along a line from Pietermaritzburg to Ladysmith) and the northern region of the former Transkei. The majority of events occur in mid-summer, from November to March; however, tornadoes have also occurred in spring and early summer (September and October) and in the late summer and autumn (February to May). Most tornado events occur in the late afternoon and early evening between 16h00 and 19h00 local time.
Tornadoes normally spawn from severe thunderstorms. Goliger et al. (1997) list the meteorological features necessary for tornado formation as, firstly, a deep layer of mid-atmospheric dry air above a moist surface; secondly, steep moisture and temperature gradients; thirdly, high surface temperature; fourthly, low-level convergence and upper-air divergence; fifthly, vertical wind shear; and lastly, atmospheric instability. Once you have the above conditions tornadoes can occur.
The classification and confirmation of tornadoes still remains a challenge.
Government and the SA Weather Service needs to make the necessary resources available to study all tornadic events in South Africa. Currently it seems that tornadic events are classified as low priority in South Africa and that the general public and the press are the resources who classify and confirm a tornadic event. The public and media can play an important roll to provide information, photos, videos and eyewitness descriptions of a tornadic event. The Damage surveys should be undertaken within 12 hours after the event and before clearing of the rubble. Aerial surveys by official investigators of the effected areas are rarely done. An aerial survey is one of the methods used to assess the damage and impact on human lives. However very costly it is one of the best methods used to survey the path and damage of a tornado.
The prediction, detection and monitoring of tornadoes are one of the most important services of any organization that provides meteorological information. By assisting each other with information, data and media we can make a difference in the timely issue of warnings for severe weather. Nevertheless timely warnings remain very difficult. Severe weather events can only be accurately predicted in situations where a severe storm already exists. We need more real time Weather Observers/Watchers to assist the relevant organizations/services to improve timeous warnings of tornadoes in South Africa.
Citizens in South Africa should become more weather wise. Your preparedness and combined timely severe weather observations, could save lives.
- MSBWX
