by Johan van den Berg – firstname.lastname@example.org
Absa bank het al die afgelope 100 jaar in landbou belê en sien uit na die volgende 100 jaar saam met ons boere. Bekende name in die landboubedryf gaan verskillende vooruitsigte soos die ekonomie, die weer, gewasse, groente, vee ens vir 2017 bespreek. Hou ons webblad dop om almal te lees.
El Niño or La Niña?
The El Niño phenomenon had already dissipated by the middle of June 2016. This made way for neutral to poor La Niña conditions. Most predictions indicate that sea surface temperatures at the La Niña side will remain neutral for the rest of the season up to at least autumn 2017. At that point in the season rapid changes, such as the redevelopment of El Niño conditions, are very unlikely.
In July 2016 the Indian Ocean Dipole (IOD) index showed the strongest negative trend over the past 50 years. At the time of publication it was still strongly negative and ought to remain negative for the following couple of months. If the IOD is negative, it is a sign that there is cooler surface water in the western Indian Ocean (on the African side of the Indian Ocean) and warmer water more to the Australian side of the ocean. Cyclonic and low-pressure activities will therefore occur further to the east in the Indian Ocean, which will have very little negative effect on rainfall conditions over Southern Africa.
Expected implications on rainfall
The effect of neutral to poor La Niña conditions associated with the strong signal from the Indian Ocean is bound to be positive for rainfall. Although poorly developed, La Niña features will probably remain and even the neutral sea surface temperatures could at least result in normal rainfall. The expectation in the summer rainfall area is still that the chances for rain in spring and early summer remain below average, but that average and even above-average rainfall could occur in the middle to late summer. The conditions for rainfall in the eastern parts of the country improved in the last part of September and the beginning of October. However, somewhat drier conditions can occur over the eastern parts around February. For the more central parts conditions will probably be better from the middle part of October and conditions could also improve in the following months. The second part of the summer also seems to be favourable for rainfall. The western parts of the country could also begin to show increased chances of rain as from November.
When considering South Africa’s annual total rainfall since 1959/60, it is obvious that the rainfall which occurred in the past two years (2014/15 and 2015/16, 1 July to 30 June) was fairly far below average. However, this picture looks quite different if one looks at North West, for example, where four of the last five years got rainfall which was fairly far below normal. What made the 2015/16 season so extremely dry, was the cumulative effect of the drought that has been going on for a number of years already.
In view of the present forecast of a weak La Niña phenomenon and favourable Indian Ocean conditions, chances are good that the turning point of the poor rainfall years has now been reached and that rainfall in the next season should be much better. However, the effects of the drought over the past number of years will not disappear with one good rain shower; follow-up rain, good management and time will be required, particularly for the veld to recover. On the other hand there are strong indications that drier conditions could prevail over the winter rainfall areas during the next seasons. There have already been signs of drier conditions building up over the past two winter seasons.
Although the La Niña phenomenon developing at present is not very strong and tends to be between neutral and La Niña, there is a strong positive rainfall signal from the Indian Ocean. In general a normal to above-normal quantity of rain is expected over the summer rainfall area. The season will probably begin a bit later than normal but quite a bit of rain is expected in midsummer.
Dam levels ought to respond positively in November, but more probably only in December. The cumulative effect of the drought of the past number of years will, however, still have a negative effect on the new season, even if good rains fall.
Source: ABSA agricultural outlook 2017