A new Weather Surveillance Radar system developed in 1988. A strong downdraft, initiated by a thunderstorm, that includes an outburst of damaging winds on or near the ground. Downbursts may last for anywhere from a few minutes in small scale microbursts on up to 20 minutes in lager , longer lived microbursts. One example of a downburst, called straight-line winds, can reach speeds of 176km to 240km, or squarely in the range of a strong tornado. Dryline A narrow zone of extremely sharp moisture gradients.
Thundershowers usually develop just to the east of the dryline in South Africa.
Nino Significant warming of the waters in the eastern Pacific Ocean, usually off the coast of South America, which results in shifts of world-wide weather patterns. Can cause prolonged periods of drought or floods. In South Africa, El Nino is associated with prolonged droughts. An area from which waves are generated by a wind that is nearly constant in direction and speed. Flash Flood A flood that rises and falls quite rapidly with little or no advance warning, usually as the result of intense rainfall over a relative small area.