The front

[Jim_From_Zim]

Nav, you're waaaaaayy off. Yours is more like a reverse storm front on the highveld

Basically, a cold front is a low pressure system turning clockwise. We all know that air moves from a high pressure to a low pressure right? So as the front turns past cape town, it leaves a void behind it that needs to be replaced. So the warmer air is 'sort of' being sucked in behind it which comes from the high pressure that gets fed warmer air from the ITCZ (inter tropical convergence zone) and mid atlantic. This high pressure sits to the W of the country and feeds the back side of the low pressures that swing past the cape. Hence the rain comes when there is a NW wind. Warm moist air over a cold surface = rain.

Make sense?