A strong cold front can cause very cold conditions and snow in some places across the southeastern parts of the country from Saturday.
By Alani Janeke, senior journalist at African Farming and Landbou.com
Reasonably good rainfall occurred over parts of KwaZulu-Natal over the past weekend, with up to 81mm measured at Charters Creek, while 50mm was recorded at Richards Bay. At Port Edward, some 33mm fell, and 25 and 21mm fell at Newcastle and Mooi River, respectively. Precipitation also occurred over parts of the Eastern Cape, although this was less than expected. Rain also occurred over the winter rainfall area on Thursday and Friday, although the precipitation was lighter than before.
“It is very informative that the rainfall pattern is now starting to shift away from the winter rainfall area to the coastal areas and adjacent interior of the summer rainfall area, especially KwaZulu-Natal. Especially after precipitation occurred in April and May over the western parts of the country and Namibia. This type of pattern, where the precipitation moves from west to east, is the first sign of a normal winter rainfall pattern,” explains Johan van den Berg, independent agricultural meteorologist.
Further cold and snow
Historically, heavy snowfalls have been recorded in August, and short-term forecasts indicate that snowfall is possible over the Drakensberg Mountains and adjacent highlands until at least the first week of August. “Heavier snowfalls may occur in August, because air moisture then increases while the air is still cold, which can lead to snow formation.”
Van den Berg says a fairly strong frontal system will move across the country from the south from 26 July, causing very cold conditions over the Eastern Cape in particular until 28 July. “It seems that this frontal system will largely miss the Western Cape, and that it will move into the eastern parts of the country. Snow can also occur as far north as Newcastle, and may even occur up to Eswatini on 28 July.”
Sharp drops in temperature are predicted between 27 and 29 July. Even a warmer area like Pongola can record minimum temperatures as low as 3°C. Minimum temperatures below freezing are expected for Newcastle and Volksrus, among others. The mercury can dip even further over the interior of KwaZulu-Natal. Between 27 and 29 July, minimum temperatures of around -6°C and -5°C are predicted at Mooi River and Kokstad, respectively, with snow also possible at Kokstad. During this period, maximum temperatures are expected to drop below 15°C in some areas.
Very low temperatures can also occur over parts of Mpumalanga, with minimum temperatures of -1°C predicted at Barberton and Wit River. At the same time, even Mbombela, with its more tropical climate, can experience minimum temperatures just above freezing. “Cold air can also cause lower temperatures over Limpopo, with temperatures reaching near freezing point in places like Groblersdal, Thabazimbi, Vaalwater and Modimole. If these predictions are correct, it could cause frost damage to crops in the warmer parts of Limpopo, KwaZulu-Natal and Mpumalanga,” Van den Berg warns.
Sharp drops in temperature are also expected across the Eastern Cape between 25 and 28 July. Minimum temperatures can drop to -7°C at Barkly East, -6°C at Aliwal North, -4°C at Middelburg and -1°C at Graaff-Reinet.
Rain over winter rainfall area
Van den Berg says that while cold fronts will continue to occur regularly in the coming weeks, they are weak systems that will rather move in over the southern and southeastern parts of the country.
Frontal systems are predicted for, among other things, 31 July and the first few days of August. However, current forecasts indicate that the precipitation from these systems on the west coast and across the southwestern parts of the Western Cape will be fairly light. “Heavy rain is also not expected over these areas for the rest of August. There is still much uncertainty about the so-called ‘make-or-break month for winter grain production’ or September. Chances are, though, that less rain will occur.”
Temperatures typically rise in September and October, which increases the water demand of the grains that then grow rapidly. This can put pressure on the water supply in fields until harvest time arrives.
Rain over the summer rainfall area
Light precipitation of less than 10mm is possible over parts of the Free State, Eastern Cape and KwaZulu-Natal from 23 to 25 July. “Further light precipitation can occur again across the central to eastern as well as the southeastern parts of the country in the first week of August,” says Van den Berg.
“Although rains are starting to fall in places, it is not yet indicative of generally good summer rains. Long-term forecasts are fairly negative for spring and early summer rainfall, but rain patterns for rainfall in September and October over the eastern parts of the country are more favourable than last season.”
