The potential for rain remains good over the western part of the southern African sub-continent. The weather pattern has been sharpened by an anticyclonic cell lying above the central sub-continent, i.e. northern Botswana, western Zimbabwe and southern Zambia. Last week, this pattern brought clearer weather to our skies but a layer of moisture in the alto levels remained as the cloud patterns revealed on a daily basis. When this anticyclonic core drifted somewhat eastward, the inflow of Congo air returned comprehensively.

Last Friday saw, for the Windhoek area, at least, some powerful storms build.
True tropical air storms will provide considerable amounts of rain and, as the storm breaks, the duration of such a torrential downpour can be measured in mere minutes. A brief burst provides some tens of millimetres within just about as many minutes. A more prolonged duration, even a mere 30 minutes, can provide local chaos. Figures of 90 to 100mm in such a time can wash any amount of surface: earth, gravel to even medium-sized stones anywhere were the flood takes them.
Such deluges on a widespread basis will create a water build up that results in flooding of lower lying areas across a considerable area. The northern region bears unforgettable testimony to this. Last Friday gave Windhoek a brief glimpse of such downpours. Reports of 100mm and 90mm (in a mere half-hour) from Windhoek West and Eros suburb illustrate the extent of the deluge.
On a much broader scale, that these deluge events have occurred during this La Nina season can provide interesting leads when consideration is given both to future prospects and to past records. During a La Nina event the synoptic weather patterns provide more rain-prone situations rather than last year when, even after the ENSO collapsed, the overall patterns remained indecisive.
After the first heavy downpours, the return of Congo air from surface to heights well into the alto levels  gave the incentive for thundery development across a very broad area.
With the circulation round this anticyclonic centre, lying above Botswana for the last few days, drawing southward Congo air, the prospect of this air being advected even further south, into and across our south, became real.