The latest satellite imagery from Sat24.com shows moisture already developing
On 22 November 2007 I was situated in Pretoria, Gauteng for a few days. I started the day by heading to Fourways, Johannesburg at around 9am, though my initial reasoning for visiting Fourways was not storm chasing related I was well aware that the South African Weather Service had issued a 60% probability of thunderstorms and that conditions were looking good for development with temperatures forecast to be in the upper 20s to low 30s.
While heading through to Johannesburg in the morning the skies were clear with only 1 or 2 small cumulus clouds in the distance. At around 3pm the first towering cumulus began as instability increased in the atmosphere, by 4pm there were numerous cumulonimbous clouds with a distinct strong thunderstorm forming directly to my north west with some clear inflow as evident in the pictures below.
I, unfortunately had no radar available to me while I was situated in Fourways so I was caught by surprise when the intensity of the storm picked up rapidly. The storm then became severe with some extremely strong winds along with very heavy rainfall rates. It was quite an experience as I was stuck in an area of open park with no transport. By the time the storm had passed I ended up completely soaked and a little in shock of what had just happened. I came there expecting nothing and left having witnessed a huge storm which was later reviewed by the SAWS and it was stated that the storm had caused two deaths.