Very little or no rain again occurred over parts of the Kalahari, south western parts of the Northern Cape and northern western and south western parts of the Western Cape as well as parts of Namibia.
The level of most storage dams in the Summer Rainfall Area improved due to the rain in April. The rainfall since January 2019 but especially in April 2019 was for the first time since about 2012 sufficient to replenish subsurface and deeper water levels in many areas.
Conditions in the Winter Rainfall Area are better compared to last year the same time, especially over the Southern Cape areas. Rain is now needed to plant the winter crop before the end of May. Storage dam levels are still low but with the rainy season about to start it will hopefully improve dam levels.
2. El Nino and Indian Ocean
Sea surface temperatures remain at weak El Nino levels. Although it is too early to have certainty about the status of surface temperatures in the Nino areas in the next months, are there some indications of a weakening of El Nino conditions. The main reason is the cooling of sub surface water temperatures in the Nino areas that is now rapidly taking place. More certainty will only be obtained from about July with regards to the prospects for the next summer season.
Warming of the Indian Ocean over a large area to the east, northeast and south of Madagascar took place since the second part of February and the average surface temperatures were about 2 to 3˚C warmer than normal in April 2019(https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf). This was responsible for the development of tropical cyclones that occurred over Mozambique, Tanzania and around Madagascar this late in the season.
3. Expected rainfall and temperature conditions
3.1 Summer Rainfall Areas
3.1.1. Rainfall
Very little further rainfall is forecasted for the Summer Rainfall Area for the winter and spring. With the possible weakening of El Nino into neutral conditions for months to come is the probability for rain in spring also low over most of the Summer Rainfall Area.
If El Nino-conditions weakens in the next months is it very possible that it may indicate the start of a wetter rainfall cycle for most of the Summer Rainfall Area from mid to late summer. Improved rainfall outlooks together with very good subsoil water conditions can result in favourable production conditions for the 2019/20 season.
The current wet conditions and expected rainfall in the summer of 2019/20 can increase the risk for animal and plant diseases and pests.
3.1.2 Frost and low growth temperatures
The risk for frost damage more or less expired towards the end of April 2019 due to most crops reaching maturity except for very late planted sunflower. Very little frost damage is reported to summer crops but crop damage due to a lack of heat units and the presence of temperatures below 10˚C is possible. A high cloud load also occurred in April, reducing the radiation levels of the sun.
Indications are that the coldest part of winter will be again in July and August with mild to warm temperatures before that.
3.2 Winter Rainfall Areas
Although some rain occurred over parts of the Western Cape, especially the Southern and Eastern Cape, originated it more from summer rainfall systems than from the contribution of cold fronts. The prospects for rain are not very favourable for most of the month of May but can improve towards the last week of May and first part of June
3.3 Namibia
It is likely that very little rain will occur for the next months and with a possible late start of the summer rainfall season of 2019/20.
4. Summary and conclusions
Better than expected rainfall conditions occurred in the last part of April over large parts of South Africa but drought conditions still prevails over the western and south western parts.
Very little or no rain is expected for most of the country until at least the last week of May when some rain is possible, especially over the southern and eastern coastal areas. The lack of rain may hamper the planting of winter crops in the Winter Rainfall Area, especially the Swartland.
El Nino is still present but there are now for the first time indications that it will most probably weakens during winter to become at least neutral for the summer of 2019/20.
